Skip to main content

Full text of "[Bulletins on forest pathology : from Bulletin U.S.D.A., Washington, D.C., 1913-1925]"

See other formats 


ill 


— 


\ 

Eee 
oT 
sd 
a 
(acannon 
sel 


aa 
0 
rm 
ca 
m 


i mer 

ii iy ; 1 i 
: Ly Oseriemstine ; trefit 
4. 


on 
FOREST PaTHoLocy | 


( from ‘, 


BULLETIN U.S.D.A+ ij ek 
WASHINGTON D.C. ) , 


(Complete Set) y 


m6, 44,89, 116,169,212, 
BEE) 360, oe tol 
37, E90) pF 
722,799, 

24, S87 loZt; 195%, 
stg MA, 4/40, 165, 


* 


fe” 


Boyce, J.-S.e: A Study of Decay in Douglas Fir in 
the Pacific Northweat. Bul.U.S.D.A. 1163: 
1-19. 1923. 


wnna-------; The Deterioration of Felled Western 
Yellow Pine on Insect-Control Projects. 
Bul eUeSeDeAc 1140: 1-7. 1923. 


emananem----; Decays and Discolorations in Air- 
plane Woods. Bul.U.S.D.A. 1128: 1-51. 1923. 


wowen-------; The Dry-rot of Incense Cedar. Bul. 
U.SDeA. 871: 1-58. 1920. 


Hartley, Carl: Damping-off in Forest Nurseries. 
BuleUeS-DeAe 934: 1-99. 1921. 


amen eee eam : The Control of Damping-off of 
Coniferous Seedlingse Bul-eU.S.DeAe 453: 
1-32. 1917 @ 


wee ener nna ne : Injury by Disinfectants to Seeds 
and Roots in Sandy Soils. Bul.UeSeDeA. 
169: 1-35. 1915. 


aoeeeenew-e-=; The Blights of Coniferous Nursery 
Stocke BuleUeSeDeA 44; 1-21. 1913. 


Hedgecock, George Ge, & Long, William He: A Dis- 
ease of Pines caused by Cronartium Pyriforme. 
BuleUeSeDeAe 247: 1-20. 1915. 


Howard, Nathaniel 0.: The Control of Sap-stain, 
Mold, and Incipient Decay in Green Wood with 
Special Reference to Vehicle Stock. Bul. 
U-SeDeAe 1037: 1-55. 1922. 


Hubert, Ernest E.: Effect of Kiln Drying, Steaming, 
and Air Seasoning on Certain Fungi in Wood. 
BuleUeSeDeAe 1262: 1-20. 1924. 


Humphrey, C.J.: Timber Storage Conditions in the 
Eastern and Southern States, with Reference 
to Decay Problems. Bul.U.S.DeA. 510: 1-42. 
1917. 


‘al 
Aw 


“ 
J 
olan he 


; 


. 5 
a - . ‘, ae vl are aie 


| a 
+h ‘ 
A 
* 
™ ‘ A \ | es 
i 
I 
7 . . . i 4 
\ 
i 
' 
! if -—- 
ig ’ . } 
. Ps 
: 
y - i 
ae 
: ? \ 
_ ‘ 
, 
y eel | 
4 4 ‘ at 
iM / : ed - ale 
a " oe ‘ 
i ; 
: \ - ™ - } 
y . 
Fe * 
a) | 
'] 
el 
i : 
ik 
. 4 + ‘ , r 
i te 
* ee 
7 ( 
- * 4 = , os, de et 
i 
; « 
‘ 
‘ \ . ‘i 
‘ 
‘ 
‘ d _ ; 
. one i, 
® ’ 
pa 
ie 
i 
. e -_ 
: 
gi 
i 
' 
\ 
* 
% . ~ 2 
* 
\ 
i bo 
rd 
i * r 
ts : 
‘| ‘ ,' Me 
) { { 
he * 
hy 
4 4 “TF ¥ 
s _ a et 
Me eae Thea 
, 
\ r 
) if 
;o7 
‘ i Mr 
() ; 
i . 4 " i , ro 
i / 
‘Tae 
Lay 
i 


Humphrey, CeJe, & Fleming, Ruth M.: The Toxicity 
| to Fungi of Various Oils and Salts, partic- 
ularly those used in Wood Preservation. 
Bul eUeSeDeAe 227: 1-38. 1915. 


Korstian, Clarence F., & Long, WeHe-: The Western 
Yellow Pine Mistletoe. BuleUeS.DeA- 1112: 
1-35. 1922. 


Kress, Otto, Humphrey, C.J., Richards, OCA, 

Bray, MeWe, & Staidl, J.-A: Control of Decay in 
Pulp and Pulp Woode Bul oUeSeDeAe 1298: 1-80. 
1925. trae 


Long, WeHe: The Death of Chestnuts and Oaks due to 
Armillaria Mellea. Bul.U.S.D.A..89: 1-9. 
1914. 


sonnn-----: A preliminary Report on the Occur- 
rence of Western Red-rot in Pinus ponderosa. 
Bul eUeSeDeAe 490: 1-8. 1917. 


ee denteceteeteeteren : Investigations of the rotting of 
Slash in Arkansas. Bul.U.S.DeA. 496: 1-14. 


1917. 


Meinecke, E.Pe: Forest Pathology in Forest 
Regulation. BuleUeSeDeAe 275: 1-62. 1916. 


Moir, WeStuart: White-pine Blister Rust in 
Western Europee Bul.U.S.D.A. 1186: 1-32. 
1924. 


Rhoads, Arthur S.: The Formation and Pathological 
Anatomy of Frost Rings in Conifers injured 
by Late Frostse BuleUeSeDeAe 1131: 1-15. 
1923. 


Shear, Cole, Stevens, NeEe, & Tiller, R.J.: 
Endothia parasitica and related Species. 
BuleUeSeDeAe 3803 1-82. 1917. 


Snell, Walter H.: Studies of certain Fungi of 
Economic importance in the Decay of 
Building Timberse Bul.U.S»DeA. 1053: 1-47. 
1922. 


} i soem ROE . 
RE hile Be jin 
. J Ws rie a 


Vee meer oem 
i 


Spaulding, Perley: New Facts concerning the 
White-pine Blister Rust. Bul.U.S.D.A. 116: 
1-8. 1914. 


 eelaalensientanieeten eatenteteeteeentenar : Investigations of the White- 
pine Blister Rust. Bul.U.SeDeA « 957: 
1-100. 1922. 


Weir, James Re: Larch Mistletoe: Some Economic 
Considerations of its Injurious Effects. 
Bul.UeSeDeAe 317: 1-25. 1916. 


sean lentertenientantenteatentee’ : Mistletoe Injury to Conifers in 
the Northwest. BuleUeSeDeAe 360: 1-39. 1916. 


---~~~~~-----~: Forest Disease Surveys. Bul. 
UeSeDoAe 658: 1-235. 1918. 


annn=-~-------; Observations on the Pathology of 
the Jack Pinee Bul.UeSeDeAe 212: 1-10. 1915. 


wownewenwennn-~, & Hubert, Ernest E.: <A Study of 
Heart-rot in Western Hemlock. Bul.U.S.DeA. 
722: 1-39. 1918. 


tea teaaaeateeeneereetes ween nw en nn ew ewe nn----; A Study of 
The Rots of Western White Pine. Bul.U.S.D.A. 
7993 1-24. 1919. 


ahaa b 
Pir ebe ih 

wed yt 
Lethe 

‘ 

e i 
" 
4 


Bs Pala tp sorueeura. ‘bho 


‘ i ¥ a ae 
bby Aka om o! BREG ovipudy 
) et PEF 
, t 
4 
 . + ‘ ; he ? : 
f # : n} % ty Ag ih ae ye i, Y 
Bhi J St se |< 3 ont a, SETS s, } ' 
hn ¢7' v * » “ - 
a" - i ‘ es * aye 
nh a b mi @ + PAR ta, wom Sas Lae sa be 
ore en ‘ si 4 
(sx sat f 
© yey 
PAL ey . - ar 
on Pipe r / } : 
‘ } 0 any A y a | 4 s 
- oY i e 2 
; to ae ig mh & F 
a * .. the © Lem 
chs en et 
+ ..| * Ue By 
, seeped 
q ik ¥ 
be A 
; " R e.. 4 
’ / ; d bs Sr 3 Ts 
f ‘ : i att 
* bas * 7 * » «. « 
b ee f 
e one » A 
' ai é *Xein 
. v t 
A > 
— ‘ 7 #3) & *W¢ ny, 
4 r 
* 4 ¢ P 
s 
- - * wie C24, €3 
*. Y ahs 
t « E 
ee ee ee ee Hh ne 
oy a 
. + ; ‘ ae rs 
AL ah 
vt Le 
1) on 
d bah 
L. 
. 
i 
Ay 
ea < 
i ti %) 
i: : Ay 


* 


BULLE FIN’ ‘OF “TAE 


NMC 


No. 44. 


; Etieibaien from the Bureau of Plant Industry, Wm. A. Taylor, Chief. 
December 12, 1913. 


‘THE BLIGHTS OF CONIFEROUS NURSERY STOCK. 


bis By CARL HARTLEY, 
Assistant Pathologist, Office of Investigations in Forest Pathology. 


INTRODUCTION. 


There has been a good deal of complaint from forest and orna- 
_ mental nurseries in various parts of the country of injury to conifers 
by blight. All cases in which trees in the nursery turn brown and 
die, in whole or in part, without any very definite symptom to indi- 
 eate what caused death are classed as blight. 
The damping-off diseases and those caused by the rust fungi, de- 
_ tailed descriptions of which may be found in a bulletin by Spaulding, 
‘ee are not included under the name “ blight.” Damping-off attacks only 
very young seedlings, doing most of its damage during the first three 
_ weeks after germination. It is caused by several parasitic fungi 
_ which attack the soft tissues of the tender seedlings and rot them, 
_ often entirely destroying great numbers of plants in a few days. 
Unfortunately one of these fungi sometimes continues to kill seed- 
gs for a time after they have become older and tougher, so that 
ey look more as if they had been killed by a bEeek than by 
ene ot : 
Bend Because of the difficulty in finding a “natural livadene: line be- 
tween the damping-off diseases and the blights, it has become neces- 
ry to draw an arbitrary line between them. All parasitic death of 
edlings less than 2 months old will be classed as damping-off. The 
eason for this classification will be presented under the heading 
i ‘Root- rots.” The present paper will consider as blights only diseases 
of stock more than 2 months old. Since the rust fungi are not com- 
“mon in our nurseries and make their presence known before the 
death of the plant by swellings of the stems and by the breaking out 
A of orange- colored spore pustules, there should be no difficulty in dis- 


ie 
; 
‘ 4 


- 3 Spaulding, Perley. The blister rust of white pine. U.S. ie patenent of Agriculture,, 
Bureau of Plant Industry, Bulletin 206, 88 p., 2 pl., 5 fig., 1911. 


13745°—Bull. 44—1383——1 


2 BULLETIN 44, U. S. DEPARTMENT OF AGRICULTURE. 


tinguishing between blights on the one hand and damping-off and 
rusts on the other. 

Losses caused by blight are very considerable, nurseries not infre- 
quently losing practically their entire stock of one or more species of 
conifers by blight attacks. In many of these cases both the cause of 
the attack and methods of preventing or stopping it have been en- 
tirely unknown. No systematic investigation of these blight attacks 
had been undertaken in this country. In studying the problem the 
writer since 1909 has visited 31 nurseries which raise conifers and 
has corresponded with many others. Many different types of blight 
have been found to exist. By his own observation and experimental 
work and by bringing together the information obtained from prac- 
tical nurserymen and from the European literature on nursery dis- 
eases, the writer has succeeded in distinguishing quite clearly be- 
tween the most important types of bight and drawing conclusions as 
to the best preventive measures. In the following pages the causes, 
distinguishing characters, and preventive measures for all of the 
types of blight met with are given as fully as the present condition 
of our knowledge will permit. 


PHYSIOLOGICAL TROUBLES. 
SUN SCORCH. 


Sun scorch is the commonest and most serious trouble in most of 
the nurseries. By sun scorch is meant the death of entire seedlings 
or transplants or parts of them, due to lack of balance between the 
water absorption by the roots and water loss from the needles during 
the growing season. Stated in a somewhat simpler way, sun scorch 
is drought injury which occurs in the growing season. The term 
“ sun scorch ” has been used by Stone? and others for a similar trouble 
of conifers in New England forests. Its work in second-year seed 
beds on sandy soil has been described by Hartig.? It will be con- 
sidered in ‘detail, because in many cases it resembles other diseases so 
closely as to go unrecognized. For example, sun scorch for several 
years caused heavy losses in both seedlings and transplants at the 
Forest Service nursery at Halsey, Nebr., where most of the writer’s 
work on this disease has been done. In a single case the records indi- 
cated a loss of 70 per cent of all the 2-year-old seedlings of jack 
pine (Pinus divaricata ( Ait.) Gordon) and Scotch pine (P. sylwes- 
tris L.). The damage looked so little like drought that for some 
time it was supposed to be due to parasitic fungi, and Bordeaux 
mixture was employed to control it. Losses from this disease have 

1 Stone, G. E. Sun scorch of the pine. Massachusetts Agricultural Experiment Sta- 


tion, 22d Annual Report, pt. 2 [1909], p. 65-69, 1910. 
2 Hartig, Robert. Lehrbuch der Baumkrankheiten. Aufl. 2, Berlin, 1889, p. 104. 


BLIGHTS OF CONIFEROUS NURSERY STOCK. 3 


. 
occurred at nurseries in Colorado, Minnesota, Pennsylvania, and 
New York without being recognized by the nurserymen. 


HOW SUN SCORCH WORKS. 


In serious cases of sun scorch, seedlings of all ages are killed out- 
right. In less serious cases part of the plant is killed. Either the tips 
or the lower needles may be first affected. If the tips are injured, 
stem and bud may be killed as well as the needles, so that growth 
can be resumed only by lateral buds below the point of injury. In 
slight attacks only the needles, and often only the tips of the needles, 
are killed. When the lower needles are the only ones attacked, 
despite the fact that they are well protected from sun and wind in 
dense stands, it must be assumed that the younger needles at the 
tips, subjected to much more light and wind, have survived at the 
expense of the lower ones by taking more than their share of the 
available water. Affected needles first turn slightly yellowish, lose 
their green until they have become a pale straw color, and then grad- 
ually turn deeper brown until they become nearly red. In summer 
most dead needles fall within a month. 

In crowded seed beds, especially on very sandy soil, attacks may 
take place very suddenly in hot, dry weather, and patches of seed- 
lings up to a foot in diameter may be entirely killed. It is these 
definite, clean-killed patches which have most often caused the disease 
to be called parasitic. Such even death can be explained on a drought 
basis only by assuming that in such cases the root systems of all the 
seedlings involved have been equally extended in normal competition 
for water, just as the tops often grow to an exactly even height in 
competition for hght, so that all the seedlings in the patch are on 
terms of equality when the competition becomes critical. When part 
of the seedlings in a crowded bed are badly suppressed the smaller 
seedlings are in some cases, when transpiration is rapid, even less 
subject to sun scorch than the larger. Since the suppressed seedlings 
presumably have less extensive root systems, their endurance in such 
cases must be explained by the fact that they are also less subject to 

water loss because of the protection afforded by the tops of the larger 
plants around them. When the beds are not crowded and the 
weather does not favor extremely rapid water loss, death does not 
occur so suddenly or in such definite patches. 

In the cases of transplants a certain number die soon after they are 
set out and before root growth starts. This has been called “ trans- 
planting loss” and is not included under the term “sun scorch.” 
“Sun scorch ” is used in transplants for death due to excessive: water 
loss after the plants have become partly established and commenced 
growth. The work of sun scorch in transplant beds at Halsey differs 
from that in seed beds in that the trouble in the transplants does not 


4 BULLETIN 44, U. S. DEPARTMENT OF AGRICULTURE. 


occur in such distinct patches; and if any part of a transplant is 
affected; either an entire branch or the entire plant dies at once. 

A feature of sun scorch in nurseries, as well as in the older trees 
described by Stone,! is that the absorbing portions of roots die at the 
same time as the tops or even before. This indicates that the leaf 
and stem tissues can stand water loss better than the vegetative 
tissues of the roots. Especially in the case of transplants the cam- 
bium of the entire root system, or at least of the outlying portions . 
of it, has been found to be dead and brown. By the time the needles 
show the first signs of yellowing, a large part of the root cambium is 
already gone. This especially early death of a large proportion of 
the root systems of the scorched transplants is probably due to the 
fact that a tree in the transplant bed has a smaller root system im 
proportion to its transpiring surface than a second-year seedling 
would have. When only a part of the needles on a plant are killed 
it appears that the damage to the root is more extensive than to the 
tops. This is indicated by the fact that a plant which has lost part 
of its needles in an attack of this disease is more likely to succumb 
to later attacks of the same nature. Evidently the reduction in 
transpiring surface caused by the first attack is more than counter- 
balanced by the reduction in absorbing surface. 

During several sun-scorch attacks at Halsey, and at two or three 
other times when the weather was hot and dry but no actual sun 
scorch had occurred, a peculiar type of injury appeared on young, 
growing shoots of second-year pine seedlings. White, shrunken, 
watery-looking patches appeared on the green stems rather suddenly, 
followed by the death of the plant beyond the point attacked. A 
very similar “ white-spot” injury, occurring near the bases of the 
stems of seedlings less than a month old at the Halsey nursery, and 
which has often been confused with damping-off, can be controlled 
by shading and watering. While a parasite may be in some way 
concerned in causing the trouble in both ages of stock, there is little 
doubt that drought and possibly also excessive light or heat working 
independently are mainly responsible. This white-spot injury to 
second-year seedlings is included under sun scorch because it often 
occurs simultaneously and can be prevented by the measures which 
prevent scorch. It is not important. 


EVIDENCE AS TO CAUSE OF SUN SCORCH. 


The conclusion that the disease is due to disproportionate water 
loss is based on the following facts: 
(1) Spraying with fungicides has failed to control the trouble. 
While spraying experiments have not been exhaustive, Bordeaux 


1Stone, G. E. Sun scorch of the pine. Massachusetts Agricultural Experiment Sta- 
tion, 22d Annual Report, pt. 2 [1909], p. 65-69, 1910. 


BLIGHTS OF CONIFEROUS NURSERY STOCK. 5 


mixture, ammoniacal copper carbonate, and copper acetate were 
tested repeatedly during several seasons. Unfortunately for the 
experiments, little trouble with the disease occurred at the times 
when the fungicides were used. In four cases, however, the disease 
attacked parts of the nursery containing experimental plats which 
had been more or less recently sprayed with copper mixtures con- 
taining soap. In these cases there was no evidence that the fungi- 
cides afforded any protection. This lessens the likelihood that needle 
parasites are concerned in causing the disease. 

(2) On sandy soil the attacks which most closely imitate parasitic 
injury by killing definite patches occur suddenly and often simul- 
taneously in many parts of the nursery. Serious damage may appear 
through thousands of square feet of seed beds inside of 48 hours 
from the tine the first evidence occurs. This renders it unlikely 
that root parasites play any important part in causing the disease. 

(3) The most typical attacks of the disease observed at Halsey 
occurred on days when wind and temperature were high and humidity 
low and following nights which had been unusually warm and with- 
out dew—conditions which favor excessive transpiration. This em- 
phasizes the relation of transpiration to the disease. 

(4) In general, the most trouble occurs during dry seasons. The 

larger commercial nurseries in Minnesota and Iowa report that the 
most serious trouble they have had was during the very unusually 
dry summer of 1910. 
(5) Partial shade greatly decreases loss and entirely prevents 
trouble except in very severe attacks or during persistent drought. 
Shade was tested in five different attacks at Halsey in 1908, 1909, and 
- 1910, and in all cases controlled or greatly lessened the losses, as 
indicated by the results in adjacent shaded and unshaded plats. 

(6) Crowding strongly predisposes to the trouble. In the beds at 
Halsey the seedlings at the margins which have sent their roots out 
into the unoccupied paths are practically never attacked, though in 
some cases the entire interiors of beds have been killed. This im- 
munity of the edges of the beds is more marked on sandy soils than 
on heavier ones. . 

(7) Attacks of the disease regularly occur when the soil is very 
dry. Very sandy soils, which are more quickly reduced to a low 
water content, are the commonest locations for the disease. In two 
different attacks at Halsey direct comparisons were made of soil 
moisture in diseased and relatively healthy areas, taking samples 
between the depths of 7 and 11 inches, where the greatest mass of 
absorbing roots lay. In one case the samples from the four points 
tested in the healthy area showed an average water content 32 per 
cent higher than that of the two points taken in the blighted stand 
adjacent. At the time of the other attack four samples were taken 


6 BULLETIN 44, U. S. DEPARTMENT OF AGRICULTURE. 


from the blighted area and two from the healthy, and determination 
showed 30 per cent more water in the samples from the healthy area. 
Altogether, samples taken at 10 different points in diseased stands 
during three different attacks gave an average moisture content of 3.4 
per cent for the soil from 2 to 11 inches in depth. The average wilting 
coefficient of the soil at this nursery, determined from samples taken 
from the same depths at nine different points located in the same 
parts of the nursery as the moisture determinations above referred 
to, was 3.6 per cent, as determined by the indirect method of Briggs 
and Shantz from moisture-equivalent determinations made by the 
Laboratory of Biophysical Investigations. While the soil-moisture 
determinations made were too few to establish the relation of dry 
soil to the disease, they are to be viewed as contributory evidence. 

(8) High points in beds and the centers of arched beds from which 
the water runs off or which are missed in flood irrigation are espe- 
cially liable to damage from the disease. 

(9) Species which normally inhabit moist soil suffer most. Nor- 
way spruce (Picea excelsa Link) and Douglas fir (Pseudotsuga taai- 
folia (Poir.) Britt.) seem to suffer oftener than the pines. Western 
yellow pine (Pinus ponderosa Lawson) grown from Rocky Mountain 
seed is more resistant at Halsey than other pines. 

(10) Sufficiently frequent and heavy watering will entirely pre- 
vent the disease. In three different attacks at Halsey evidence of 
the preventive effect of watering was obtained. The main practical 
fact is that for two seasons the nurserymen at Halsey and at Monu- 
ment, Colo., have practically controlled the disease by increasing the 
frequency of watering. At these nurseries during the three preced- 
ing seasons the disease had caused considerable loss. At both these 
nurseries the disease had been considered parasitic. 

It is not thought that death is usually due to the entire lack of 
available soil moisture. It is rather probable that it usually occurs 
when there is still a certain amount of available water left in some 
part of the soil reached by the root system, but so small in quantity 
that it can not be taken up by the roots fast enough to supply the 
demands of the rapid transpiration loss from the needles. This does 
not necessarily mean slowness of imbibition; it may simply mean ~ 
that the capillary water movement from outlying soil particles to the 
particles adjoining the root surface is too slow when the soil is nearly 
dry. That this is the case is indicated by the fact that after an at- 
tack of sun scorch has started as the result of one or two days of 
rapid transpiration, when the soil is quite dry, the disease may stop 
spreading on the advent of cooler weather without the addition of . 
any water to the soil from above. 

Some interesting occurrences at Halsey in connection with this 
trouble. which at first appeared to contradict the relation of the dis- 


BLIGHTS OF CONIFEROUS NURSERY STOCK. 7 


ease to water loss, may be mentioned. Losses have frequently been 
more serious in the nursery transplant beds than in the trees planted 
out in the sand hills, where there is ttle humus and no wind pro- 
tection and where no artificial watering is done. This was advanced 
as an argument against drought as a cause of the trouble. The fal- 
lacies in this argument are that the trees used in the hills had been 
_ previously once transplanted, so that they were stronger and better 
rooted stock, and that in the hill plantations there was not so much 
competition as in the transplant beds, where the close stands of trees 
exhaust soil moisture very rapidly. 

Another argument against drought as a cause of the disease was the 
fact that in certain cases the blight appeared at Halsey when the soil 
2 or 3 inches down seemed quite moist. However, further examina- 
tion and quantitative determinations of moisiure content showed that 
at such times the soil around the mass of absorbing roots is drier 
than the soil near the surface. The dense stands of seedlings appar- 
ently exhaust the soil moisture at the lower levels more rapidly than 
evaporation takes the water nearer the surface. 

A further argument advanced against the drought theory is the 
fact that at Halsey trouble often occurs within a very few days after 
fairly heavy rains. This happens, however, only in very drying 
weather and in beds where the stand is dense. Under such conditions 
the moisture is drawn from the sandy soil very rapidly, so that in all 
such cases the soil around the roots is found to be very dry despite 
relatively recent rains. 

One case of sun scorch occurred at Halsey in 1910 which was quite 
difficult to explain, although the evidence presented by adjacent plats, 
some of which had been shaded and some especially watered, left 
little doubt as to its relation to drought. On July 25 and 26 a period 
of hot weather culminated in temperatures of 100° and 96° F., respec. 
tively. At about 7 a. m. July 27, 0.28 inch of rain fell. The sky 
cleared immediately after, the temperature rose to 102°, and the air 
became dry. July 28 was cool and cloudy. On that morning a large 
number of the smallest grade of 2-year-old jack-pine transplants had 
begun to turn yellow, and in 24 hours about one-third of all the 
stock of this class showed injury. Trees continued to turn yellow 
and die in decreasing numbers during three or four days of cool, 
partly cloudy weather following till the loss reached fully 50 per 
cent. The 0.28 inch rain of the 27th appeared to penetrate to the 
roots through the rather coarse soil. The best explanation seems to 
be that the roots were injured by the excessive demand on them dur- 
ing July 25 and 26, before the rain fell, or on July 27, before the rain 
had time to get down to the root level. The failure of the tops to 
show injury till some time after the roots are hurt is always more 
marked in transplants than in seedlings. There seems to be no rea- 


8 BULLETIN 44, U. S. DEPARTMENT OF AGRICULTURE. 


son to think that the high temperature of July 27 injured the trees 
directly. Whiue 102° F. is unusually high, the temperature has gone 
to 107° at this nursery without injury to the pines. 

The death of the roots, especially characteristic of sun scorch in 
transplants, has led to the belief in some quarters that root parasites 
were the immediate cause of the disease. The evidence obtained con- 
tradicts this view. The most that can be said is that in many places 
some of the common soil fungi may act as facultative parasites, kill- 
ing weakened portions of root systems and so making the plants some- 
what less able to withstand drought injury. Even this has not been 
demonstrated, and from the nature of the case it is practically im- 
possible to demonstrate it. An attempt was made to secure evidence 
on this point by carefully washing the roots of healthy 1-year-old 
jack-pine seedlings and planting part in autoclaved soil and part in 
untreated soil. All the soil used came from part of a bed at the 
Halsey nursery which had been affected with sun scorch. After the 
plants had had a few weeks to become established all the pots were 
allowed to dry out. Death occurred in a manner fairly character- 
istic of sun scorch, coming at practically the same time in both steri- 
lized and unsterilized pots. Microscopic examination indicated about 
the same fungi in the dead roots in both sterilized and unsterilized 
soil. The results were entirely negative. Because of the impossi- 
bility of securing a growth of stock large enough to exhibit typical 
blight symptoms and of keeping any of it free enough from common 
soil organisms to use as controls for inoculation tests, there is little 
chance of learning anything definite as to what part fungi may play 
in causing sun scorch. 

Taken as a whole, the evidence is believed sufficient to establish a 
jack of balance between water absorption and water loss as the chief, 
if not the only, cause of the disease. While there have at times been 
occurrences rather difficult to explain, 13 different attacks of the 
disease have been seen at Halsey, and in all of them evidence has 
been obtained of the relation of the trouble to drying weather, shade, 
crowding, or soil moisture, and in most cases to two or more of these 
factors. The Halsey nursery has been under fairly continuous ob- 
servation by the writer during the summers of 1909, 1910, 1911, and 
1912, and it can be said quite positively that all the serious losses 
which occurred in established stock over 1 year old during the 
growing seasons in this period could have been averted by maintain- 
ing sufficient soil moisture and mostly averted by shading. While 
the conditions are in many ways different from those at other nurser- 
ies, the evidence here obtained has been checked up by observations 
made at many other nurseries from the Rocky Mountains to the 
Atlantic coast. While some of the other diseases listed in this paper 
undoubtedly are concerned in the spring and summer losses at many 


BLIGHTS OF CONIFEROUS NURSERY STOCK. 9 


of the nurseries, the writer is confident that the largest proportion of 
the damage to pine, spruce, and fir nursery stock during the growing 
season can be classed as sun scorch. _ 


HOW TO RECOGNIZE SUN SCORCH. 


The best way to tell whether or not an attack of blight is due to 
sun scorch is to note the relation between the occurrence of the dis- 
ease and crowding, shading, drying weather, sandiness of soil, lack of 
soil moisture, and drought resistance of different species, as described 
in the foregoing paragraphs. The only characteristic of value shown 
by individual diseased plants is the simultaneous death of needles and 
root tissue. When the character of the trouble is still in doubt, final 
determination must rest with the nurseryman. The best method of 
doing this is to lay out small plats in the beds at different points in 
the nursery, giving some of them special shade and others regular, 
heavy watering. If at the next attack of blight these treated plats 
come out much better than the other beds near them, he can know 
that the trouble is sun scorch and treat it accordingly. 


PREVENTIVE MEASURES. 


The best and only absolutely certain way to prevent sun scorch is 
to water the nursery beds. When stock over two months old is 
watered it should be watered heavily. The great trouble with arti- 
ficial watering is that it is usually not done thoroughly. Most of 
the water appled in sprinkling with the hose, as it is often done, 
evaporates from the surface without reaching the roots at all, so that 
even frequent sprinkling is of little value. At Halsey very crowded 
beds must be heavily watered oftener than once a week in the most 
drying weather to prevent all injury from sun scorch. With one ex- 
ception there is no other nursery known to the writer where so much 
watering is necessary. The density of the stand and the character 
of the soil and climate must determine the amount of watering needed 
to prevent trouble. In some nurseries on rather heavy soil no pre- 
ventive is necessary except in most exceptional drought vears. 

Objection has been made to much watering, on the ground that 
it can be expected to make stock less hardy and less able to sur- 
vive transplanting. Observation of the work of the disease has sug- 
gested that the other extreme may also decrease hardiness. If the 
trees are allowed to become too dry, many which are not killed en- 
- tirely and which may show little or no damage above ground appear 
to have enough of their root systems killed to decrease their chance 
for survival. 

At the nursery at Halsey, Nebr., the beds are flooded with water 
obtained by a lift of a few feet from a river. At Monument, Colo., 


13745°— Bull. 44—13——2 


10 BULLETIN 44, U. S. DEPARTMENT OF AGRICULTURE. 


the beds are watered by large portable sprinklers fed from a moun- 
tain reservoir. Kven with such excellent equipment much watering 
is expensive. Most of. the commercial nurseries have very crude 
watering facilities and many of them none at all. At many nurseries 
putting in a watering system simply to prevent sun scorch would not 
pay. Indirect methods of controlling the disease are therefore of 
interest. : 
Shade frames of 2-inch slats, half an inch thick and spaced 2 inches 
apart, have proved a cheap and quite effective method of controlling 
the trouble at Halsey, though they do not prevent all loss. This slat 
shade was tested on July 26, 1910, at noon and at 4.20 p. m., with a 
photometer using “printing-out ” paper. An average of eight deter- 
minations indicated that the shaded beds received 42 per cent of the 
amount of light received by unshaded beds at the same times of day. 
While this proportion must vary with the angle of the sun’s rays, the 
average figure obtained is considered fairly representative for the 
period of most rapid transpiration. Therefore, the term “ half shade,” 
regularly used for this type of shade, while the best available, is not 
entirely accurate. When frames are only a foot above the ground, the 
slats should be placed north and south in order that all parts of the 
bed may get a reasonably uniform amount of shade. Shade put on 
after the attack has gone far enough to become noticeable can not pre- 
vent all injury, but may decrease it. In the cases of the successful use 
of shade seen by the writer the shades had been put on several weeks 
before the attack took place. Brush supported by rough frames 6 
feet high is much used over all ages of seedlings by western commer- 
cial nurserymen and probably explains much of their relative free- 
dom from sun scorch. Shade presumably keeps the beds from get- 
ting as dry as they otherwise would and at the same time enables the 
plants to live in drier soil than they otherwise could, by reducing the 
rate of transpiration loss from the needles. In growing stock for 
western forest planting, where it is difficult to secure survival, there 
appears the theoretical objection that shade in the nursery beds will 
make the stock more tender and harder to transplant successfully. 
Bates and Pierce?’ state that the half shade used at Halsey when kept 
over second-year seed beds has resulted in greater loss in the trans- 
plant beds the following year. They suggest gradually reducing the 
amount of shade on second-year seed beds. In the case of transplant — 
beds it may be best to use the method tested in 1910 by Mr. C. R. 
Bechtle, formerly of the Forest Service. He erected rough temporary 
shade frames over the beds immediately after transplanting and 
removed them some weeks later when the’ trees had become partly 


1 Bates, C. G., and Pierce, R. G. Forestation of the sand hills of Nebraska and Kansas. 
U. 8. Department of Agriculture, Forest Service, Bulletin 121, p. 32, 1913. 


BLIGHTS OF CONIFEROUS NURSERY STOCK. 1d. 


established. This method tends to protect the transplants during the 
period when they have the least absorbing root surface and exposes 
them to the sun during the larger part of the growing period, so 
that by the end of the season the trees should be thoroughly hard- 
ened and ready to stand field planting. Shade will always be a 
useful adjunct in preventing sun scorch, though the extent to which 
it should be used will vary greatly with different nurseries. 

Crowding should be avoided in order to avoid sun scorch. What 
constitutes crowding varies greatly at different nurseries and with 
different species. At Halsey a second-year seed bed containing 75 
Scotch pine per square foot is crowded. At Monument 150 Douglas 
fir per square foot do not crowd each other seriously at the same age. 
Transplants should be given much more room than seedlings. The 
older commercial nurseries often practice thinning in their older seed 
beds and generally give their transplants a great deal of space. Be- 
cause of the extra cost of weeding and cultivating large areas and the 
limited space at some nurseries, it is sometimes probably cheaper to 
crowd stock in a small space and prevent scorch by increased shade 
or watering. 

Extremely sandy soils should be avoided, and any deficiency in 
humus should be counteracted by manure and soiling crops, so as to 
increase the water-holding power of the soil. Nurseries on very sandy 
soils in the Northeastern States appear to have more trouble from 
sun scorch than western nurseries, which have drier climate but 
somewhat heavier soil. Windbreaks and surface cultivation are also 
undoubtedly helpful in preventing sun scorch. 


WINTERKILLING. 


Winterkilling is generally understood to mean death as a result 
of drying when the soil and roots are so frozen that the amount of 
water given off from the leaves can not be replaced to a sufficient ex- 
tent by absorption from the soil. In this way its cause is funda- 
mentally the same as that of sun scorch, the difference being that it 
occurs while the soil is frozen. Alternate freezing and thawing is 
considered important in bringing about damage. This may be due 
simply to the increased loss of water from the needles during warm 
periods which do not last long enough to thaw out the soil materially. 
In the West, the warm winds known as “ chinooks” produce such 
sudden very warm periods in the midst of the coldest weather that 
not only small plants but even the largest forest trees are sometimes 
killed.* | 

+ Hedgcock, G. G. Notes on some diseases of trees in our national forests. III. Phy- 
topathology, v. 3, No. 2, p. 112-113, 1913. 


Hartley, Carl. Notes on winterkilling of forest trees. Forest Club Annual [Uni- 
versity of Nebraska], v. 4, p. 41-46, 1912. 


12 BULLETIN 44, U. S. DEPARTMENT OF AGRICULTURE. 


The formation of ice crystals in the younger tissues at the close 
of the thaws may also be concerned in causing injury. Trees affected 
by winterkilling in the nursery look much like trees affected with sun 
scorch. Winterkilling can be distinguished from other types of 
blight by paying attention to attendant circumstances. The most 
damage may be looked for during the hardest winters or winters with 
little snow. It is likely to be worst where the beds are least pro- 
tected by windbreaks or a mulch and in the least resistant species. 

Winterkilling and sun scorch work differently in that winterkilling 
is worst in open stands, while with sun scorch the case is reversed. 
This may be explained not only on the ground that the closely sown 
trees protect each other from drying winds, but also, as pointed out 
by Forest Supervisor Elers Koch, act as a mulch, protecting the soil 
from deep freezing. 

The ordinary measures for preventing winterkilling are to pro- 
tect the nursery beds as thoroughly as possible by windbreaks and 
to mulch the beds with straw. Mulching must be done cautiously. 
It is likely, especially if heavy or close, to result in mulch injury and — 
do more harm than good. Mulch injury is entirely different from 
winterkilling and will be considered later in this paper. fit 

Heaving is also distinct from ordinary winterkilling. The roots 
of nursery stock in heavy soil are sometimes lifted partly or entirely 
out of the ground by the action of alternate freezing and thawing. 
Both plants and surface soil are raised by the expansion of the soil 
in freezing. In thawing, the soil settles back gradually around the 
roots, which are left higher than they were previously. The process 
is entirely mechanical. Like winterkilling, heaving can be prevented 
by mulch. 


FROST INJURY. 


Frost injury differs from winterkilling in that it is due to the 
formation of ice crystals in unripened tissue, while winterkilling is 
probably due mainly to drying out, as above described. In addition 
to injury to unripened tissue above ground by early frosts, it is 
possible that early freezing of the soil injures by killing roots which 
have not yet stopped growth. According to Hartig,* trees with in- 
jured roots are likely to start growth the following spring before 
showing any effects and then turn brown rather suddenly. Very late 
spring seed sowing and encouraging the growth of stock toward 
the end of the season should be avoided, in order to get the tissues 
properly ripened up and able to endure freezing. Covering beds with 
a mulch -before the first heavy freeze should prevent injury, though 
very early mulching must be avoided. 


1 Hartig, Robert. Text-book of the Diseases of Trees. Translated by William Somer- 
ville, revised and edited by H. M. Ward. London, 1894, p. 289. 


BLIGHTS OF CONIFEROUS NURSERY STOCK. 13 


Death from late frosts in the spring is rather frequent. Jack pine, 
because of its tendency to start growth very early in the spring, fre- 
quently loses its terminal buds and young shoots as the result of 
severe frosts after growth has begun, although these young, tender 
shoots are capable of standing a temperature considerably below 
freezing without injury. Douglas fir nursery stock in the West also 
seems to be quite susceptible to such injury. The use of some form 
of shade to delay very early growth, placing beds of susceptible 
species on high ground, and possibly the use of smudges, heaters, or 
- a temporary straw or burlap mulch on nights when frost is feared, 
are methods which might be suggested for preventing spring frost 
injury.: 

 EBERMAYER’S BLIGHT. 

In Germany, Ebermayer' states that death in pine nurseries re- 
sults from sudden warm weather in early spring when the soil is so 
cold that the roots are unable to absorb water normally and make 
good the transpiration loss. The process which he described differs 
from sun scorch in that it occurs oftenest on heavy soil and when the 
soil contains excessive moisture. It differs from winterkilling in that 
it occurs after the soil thaws. He states that the best method of pre- 
vention is to decrease the transpiration loss by means of shade in the 
early spring. This blight does not occur commonly in the United 
States. 

DISEASES DUE TO PARASITIC FUNGI. 


NEEDLE-CAST. 


Lophodermium pinastri (Schrad.) Chev. causes the shedding or 
“cast” of pine needles in German nurseries and plantations. The 
disease is not known to occur in American nurseries, whatever may 
be the-case as to the presence of a fungus, but it 1s nearly certain to 
make trouble in the future in moist localities. A brief account of 
the disease, compiled from various statements of the great number 
of European writers on the subject, will therefore be given. 

The disease has been known in Germany for more than a century 
under the name of “ schiitte.” The causal relation of the parasite 
was first reported in 1852,? but was not established till some years 
later. When the parasitism of the fungus was established some 
writers apparently accepted it as the only cause of blight, while 
others, notably Ebermayer, who regarded physical factors as the com- 


1Hbermayer, Ernst. Die Physikalischen Einwirkungen des Waldes auf Luft und 
Boden. Bd. 1, Berlin, 1873, p. 251-261. ; 

Zur Schittekrankheit der Kiefer. Allgemeine Forst- und Jagd-Zeitung, Jahrg. 77, p. 
309-314, 1901. s 

2G6ppert, H. R. [Hysterium pinastri als Ursache der Schiitte.] Verhandlungen, 
Schlesischer Forst-Verein, 1852, p. 67. 


14 BULLETIN 44, U. S. DEPARTMENT OF AGRICULTURE. 


monest or only cause of blight, criticised the parasitic theory of the 
disease. The fungus now seems to be generally accepted as. the 
commonest cause of the bight of pines in German nurseries,' though 


it is recognized that other factors may also cause blight. Because — 


of the confusion arising from the controversy mentioned, the term 
“ schiitte ” has often been made to cover indiscriminately all forms of 
blight. It seems to the writer that the best policy will be to restrict 
the English equivalent term, ‘“ needle-cast,” to the damage done by 
Lophodermium pinastri. 

In Germany infection is said to take place between the end of July 
and the middle of September. The first reddening of isolated needles 
occurs in late September. In a very late fall the needles may turn 
brown and mature Lophodermium fruits appear before winter. Or- 
dinarily the disease works very slowly during the fall and winter 
and rapidly in March and April. By May, in severe attacks, 
scarcely a green needle remains. Even with practically all the 
needles killed, the weakened plants are frequently able to resume 
growth at the terminal bud, though diseased trees are less able to sur- 
vive transplanting than those not attacked. In some cases the para- 
site in the infected needles is said to enter the stem and kill it also. 

The juvenile needles formed during the first year persist for a long 
time after death, while needles of the mature sheathed form are shed 
soon after death as a result of the formation of a cork separation 
layer. It is this early shedding of diseased needles which gives rise 
to the name of the disease. Spermatia are first formed on the fallen 
needles. By the end of July mature ascospores appear, capable of 
infecting healthy needles and thus completing the life cycle of the 
parasite. It is not certain that in this country the life history of the 
fungus would be the same as has been described for Germany. Some 
of the confusion concerning etiology that has increased the difficulty 
of separating needle-cast from other troubles can be traced to the fact 
that Ebermayer’s blight, as well as death of roots from early fall 
freezing, may presumably cause the rapid death of the plants in early 
spring. 

In needle-cast and related needle diseases the following characters 
may be expected: 

(1) The first indication of disease in the needles will be the ap- 
pearance of light brownish green spots. These will not be as likely 
as most of the physiological diseases to attack the tips of the needles 
first. 

(2) Ordinarily the needles on any one part of the plant will not all 
die at the same time. 


1 Haack. Der Schiittepilz der Kiefer. Zeitschrift fiir Forst- und Jagdwesen, Jahrg. 43, 
Heft 4, p. 329-357, pl. 4; Heft 5, p. 402-423; Heft 6, p. 481-505, 1 fig., 1911. 


BLIGHTS OF CONIFEROUS NURSERY STOCK. 15 


(3) Even when all of the needles die at nearly the same time, there 
will not be the simultaneous death of the roots which occurs in sun 
scorch. 

(4) There will not be the same relation of the disease to dry 
weather and dry sandy soil as in sun scorch. 

(5) Beds which have been protected by fungicidal sprays will not 
be so likely to be attacked as others. 

In Germany needle-cast is said by Stumpft? and others to be con- 
trolled by spraying with Bordeaux mixture in July and August. 
- There is no guaranty that the same measures will be effective in this 
country. If the disease makes serious trouble in any American nur- 
series, spraying at different times of the year should be tested, using 
the 44-50 or 64-50 Bordeaux mixture containing 2 or 3 pounds of 
soap per barrel. 

Ebermayer has attacked the evidence supporting the parasitic 
origin of needle-cast, saying, among other things, that Bordeaux 
mixture may protect not by preventing the entrance of fungi so much 
as by decreasing transpiration. The writer’s experience with the 
44-50 soap-Bordeaux mixture may be of interest in this connection. | 
A heavy application a short time before the occurrence of an attack 
of sun scorch in seed beds of Pinus divaricata at the Halsey nur- 
sery had not the slightest effect in decreasing the loss from sun 
scorch, as shown by a comparison of parallel sprayed and unsprayed 
beds. The shade afforded by a “ half-shade” slat frame in one of 
these beds at this time gave absolute protection against the disease. 
This indicates that the effect of Bordeaux mixture in reducing trans- 
piration at critical times is negligible. 


PESTALOZZIA NEEDLE BLIGHT. 


Pestalozzia funerea Desm. is very common in dead coniferous nee- 
dles in the United States. Tubeuf? considers it the probable cause 
of a twig-blight of cypress trees. In the United States, Spaulding? 
induced needle disease on seedlings of Pinus ponderosa one month 
old by spraying with spores from a pure culture of this fungus. <A 
test by the writer on 1-year-old white pine (Pinus strobus L.) under 
moist-chamber conditions, using cultures from jack and Rocky Moun- 
tain yellow pines, was without result. A further test on 1-year-old 
stock by Dr. Spaulding also gave negative results. Attempts were 
made by the writer to infect green shoots on old trees of arbor vite 
(Thuja occidentalis L.), some of which had been injured by punc- 


1Stumpff. Die Schtitte und ihre Bekiimpfung. Zeitschrift fiir Forst- und Jagdwesen, 
Jahrg. 32, Heft 11, p. 675-687, 1900. 

*Tubeuf, Karl von.. Diseases of Plants Induced by Cryptogamic Parasites. English 
edition by W. G. Smith. London, New York, and Bombay, 1897, p. 493-499. 

* Spaulding, Perley. A blight disease of young conifers. Science, n. s., v. 26, No. 659, 
p. 220-221, 1907. 


16 BULLETIN 44, U. S. DEPARTMENT OF AGRICULTURE. - 


turing, or heating, or both. Viable spores from pure cultures re- 
cently isolated from arbor vite were used. No results were ob- 
tained. While the fungus is presumably parasitic in nurseries under 
some conditions, the amount of damage it has caused is unknown. 
Spraying with fungicides before infection takes place should pre- 
vent damage by it. 

OTHER NEEDLE DISEASES. 


Various fungi which have been very little studied in this country 
cause needle diseases in American forests. Though none have yet 
been reported as causing disease in our nurseries, there can be little 
doubt that some of them have made, or at least will soon make, trouble 
in nurseries in this country. Much of the comparative freedom from 
needle diseases of American nurseries, even those in the more moist 
regions, has probably been due to the fact that most of our nurseries 
are not in forests. So. far as needle diseases are concerned, it will be 
best to avoid forests of the same species as will be grown in the 
nursery in choosing sites for new nurseries. Of the fungi mentioned 
- in the literature on needle diseases, which is mainly European, the 
following species will especially bear watching: Lophodermium 
macrosporum R. Hrtg. on spruces, Lophodermium nervisequium 
D. C. on firs, Lophodermium laricinum Duby on larches, and Lopho- 
dermium brachysporum Rostr. on white pine. Lophodermium 
brachysporum has been reported by Spaulding’ as parasitic on 
needles of young white pines in Maine. Other species of this genus 
and species of Hypoderma and Sphaerella are also likely to prove 
more or less parasitic. It is probable that there are parasitic strains 
of needle fungi in foreign countries which if brought into this coun- 
try will damage our nursery stock more than any of the fungi we 
now have. No practicable quarantine or inspection system will be 
able to keep out these diseases entirely. Nurserymen should avoid 
bringing in foreign pests by using home-grown stock as far as pos- 
sible. So far as is now known seed may safely be imported, but 
bringing in growing stock should be discouraged. 

The Atlantic seaboard and portions of the extreme western and 
northwestern sections of the country, where the climate is especially 
moist during parts of the year, are the most likely to suffer from 
needle diseases. In the Middle West, where atmospheric conditions 
are relatively dry, past experience indicates little trouble with needle 
parasites in unmulched beds. It is presumable that other needle para- 
sites, like the one causing needle-cast, will be found to be aber = 
by spraying before infection takes Place: 


1 Spaulding, Perley. The present status of the white-pine blights. U. S. Department 
of Agriculture, Bureau of Plant Industry, Circular 35, p. 10, 1909. 


BLIGHTS OF CONIFEROUS NURSERY STOCK. 17 
ROOT-ROTS. 


Many soil-inhabiting fungi grow on dead roots of both seedlings 
and transplants. There undoubtedly are soil fungi which can kill 
living roots when conditions are favorable. A species of Fusarium * 
is said to have caused loss by killing pine roots in a Vermont nursery. 
Mycelial growth on roots, such as is there described, has been fre- 
quently observed by the writer, though in only part of the cases was 
it associated with any apparent injury to the plants. 

Rhizoctonia sp. (probably Corticitum vagum B. and C.), which 
causes damping-off of very young seedlings, sometimes continues to 
work in patches till the seedlings are 2 months old or even more. 
On sandy soil, when seedlings from 5 to 9 weeks old are killed, the 
youngest and deepest parts of the roots are usually first attacked. 
At Halsey roots of Rocky Mountain yellow-pine seedlings about 7 
weeks old have been attacked at points as much as 11 inches below 
the ground surface. In many seedlings as old as this the older parts 
of the roots resist the entrance of the fungus which has rotted the 
younger parts and throw out new root branches, so that recovery 
takes place without any evidence of the damage being shown by the 
plant above ground. While we ordinarily consider damping-off as 
the death of very young, succulent seedlings, the killing of seedlings 
from 5 weeks to 2 months old by Rhizoctonia is merely a continuation 
of the earlier and more typical damping-off and to a certain extent 1s | 
influenced by the treatments which control the early damping-off. 
For practical purposes, therefore, only the relatively small number 
of cases of root-rot which occur after the plants are 2 months old 
are considered as blight; root-rot of stock less than 2 months old is 
classed as damping-off. 

Root-rot of stock more than 2 months old does not appear to have 
become a serious source of loss in this country. Until more is 
learned concerning it nothing of value can be said as to characteristic 
symptoms or control measures. 


UNCLASSIFIED DISEASES. 
STEM GIRDLE. 


In Wisconsin, Oregon, Colorado, and New Mexico the stems of 2 
and 3 year old conifers in nurseries have been found constricted or 
girdled in a peculiar manner just above the ground line, and some- 
times abnormally large just above the point of girdling. The bark 
at the point of constriction is dead and often loose. The trees may 
continue in apparently good health for some time after the girdling, 


Gifford, C. M. The damping off of coniferous seedlings. Wermont Agricultural Ex- 
periment Station, Bulletin 157, p. 149-151, 1911. 


18 BULLETIN 44, U. S. DEPARTMENT OF AGRICULTURE. 


but at length gradually become yellow and die. Scotch pine, Rocky 
Mountain yellow pine, white fir (Abzes concolor (Gord.) Parry), 
Douglas fir, and Norway spruce have been found affected, the latter 
most seriously. A very similar trouble is known in Germany under 
the name “ Einschniirungskrankheit.” It is figured by Tubeuf.* 
Various coniferous and broad-leaved species are affected, beech, fir, 
and spruce being most prominently mentioned. In Germany Pesta- 
lozzia hartigii Tub. is found on the constrictions and is considered to 
be the cause of the disease. The causal relation has not been proved 
by inoculation, despite extensive experiments by Fischer.? Of the 
few cases of disease observed by the writer the fungus has been found 
fruiting on the lesions in a single case on Rocky Mountain yellow 
pine from New Mexico. In this case the bark had been dead so long 
that it had become loose. While the stem girdle in this country may 
be due to Pestalozzia hartigit, proof is lacking. 

The important practical facts are that the disease does not often 
do serious damage, and that the only method of combating it which 
can be suggested is to destroy all diseased material. All girdled 
trees with bark killed entirely around the stem are certain to die 
and should be pulled out and burned at once without waiting for 


them to turn yellow. 
MULCH INJURY. 


In nurseries where beds are covered with a mulch during the winter 
to prevent heaving or winterkilling, heavy losses sometimes occur 
while the mulch is on the beds or just after it is taken off. While 
mulch injury usually occurs during the winter it is an entirely differ- 
ent thing from the winterkilling in unmulched beds. The general 
experience of nurserymen has been that the disease was worst where 
the mulch was heaviest, or where it was composed of fine material 
which packed down into a close covering. While the injury is the 
result of the use of mulch, the immediate cause of death is unknown. 
While physical factors may be entirely responsible, it is quite likely — 
that death is due to some needle parasite whose work is favored by the 
conditions which prevail in mulched beds. What is very likely the 
same trouble occurs occasionally under a light mulch, or even under 
no mulch at all, when there is heavy or very late snow. 

In two cases the writer has had opportunity to examine injured 
white-pine and Douglas-fir seedlings shortly after the mulch was re- 
moved. In both bases the roots were still healthy despite the death 
of the needles and in many plants of the upper parts of the stems. 


1Tubeuf, Karl von. Diseases of Plants Induced- by Cryptogamic Parasites. English 
edition by W. G. Smith. London, New York, and Bombay, 1897, p. 492. 

* Fischer, C. E. C. Note on the biology of Pestalozzia hartigii, Tubeuf. Journal of 
Economic Biology, v. 4, No. 3, p. 72-77, pl. 7, 1909. r 


BLIGHTS OF CONIFEROUS NURSERY STOCK. 19 


This survival of the root after the death of the top distinctly sep- 
arates this trouble from those of the root-rot and sun-scorch types. 
The experience of a number of nurserymen shows that the disease 
can nearly always be prevented by using only loose, light material 
to mulch with and mulching no more than is absolutely necessary. 
Spraying with Bordeaux mixture just before the mulch is put on is 
worth a test at any nursery where mulch injury is frequent. 


RED-CEDAR BLIGHT. 


- In western nurseries where red cedars (Juniperus virginiana L. 
and J. scopulorum Sarg.) are grown for ornamental planting there 
is a great deal of trouble with a blight of unknown origin. A num- 
ber of nurseries have nearly or entirely stopped trying to grow cedar 
on this account. The disease is described as sometimes working sud- 
denly over a considerable area of seedlings and transplants. Since 
attacks are said to occur when adjacent pines are perfectly healthy 
it is not likely that sun scorch is responsible. In large transplants 
all the needles on specific twigs and branches die at once, indicating 
a parasitic twig blight. In the cases observed by the writer there was 
no evidence of any constriction of the twigs such as Tubeuf? has 
figured for Pestalozzia funerea twig-blight on Chamaecyparis men- 
Zlesit. 

So little is known concerning the trouble that no recommendations 
for its control can be made. It is suggested that the nurserymen who 
have the most trouble with the disease conduct experiments separately 
with watering, moderately heavy shading, and frequent spraying 
with soap-Bordeaux mixture on numerous small-scale experimental 
plats scattered through their beds. One of these methods should 
prevent or partly prevent the disease. A comparison of attacks on 
treated and untreated plats should give information both as to the 
nature of the disease and the best control method. 


MECHANICAL ROOT INJURY. 


It often happens that trees which die in the nursery can be pulled 
up very easily. Examination shows that the root has been either 
broken or eaten off 1 to 3 inches below the surface of the soil. This 
presumably is done by grubs. This type of loss is mentioned merely 
to keep it from being confused with any of the types of blight 
described in this paper. 

CONCLUSION. 


A number of different blights concerning which little has been 
known do considerable damage to conifers in nurseries in the United 
States. The increasing amount of forest planting and the danger 


1Tubeuf, Karl von. Loc. cit. 


20 BULLETIN 44, U. S. DEPARTMENT OF AGRICULTURE. 


that imported stock will bring in serious tree diseases make it espe- 
cially important that methods of controlling these blights be found, 
in order to encourage the growing of planting stock in this country. 
The writer has not only experimentally determined the cause and 
distinguishing features, but also the control methods for sun scorch, 
the most serious of these blights, and by following his recommenda- 
tions the disease has been controlled in nurseries where it had 
before done serious damage. Distinguishing characters and _pre- 
ventive measures for the two other commonest blight types, winter- 
killing and mulch injury, have also been determined. An account 
of what the writer has been able to learn from his own work and the 
experience of others with the other types of blight is also given. 
Distinguishing characters and control methods have not been found 
for all of the types. 

It is seldom that a case of nursery blight can be diagnosed merely 
by examining a few specimens of diseased trees. It is hoped to carry 
this investigation so far that each nurseryman will be able to identify 
for himself, by general observations, all of the types of blight which 
attack his nursery beds and to take the necessary steps for preventing 
further losses. 

The writer wishes to acknowledge his indebtedness to Mr. W. H. 
Mast and Mr. R. G. Pierce for their cooperation in the work at the 
Halsey nursery, to Dr. H. L. Shantz for helpful advice, and to Dr. 
Perley Spaulding, under whose general direction the work was con- 
ducted, for advice and the use of his specimens and unpublished 
data. 

SUMMARY. 


The following are the types of blight most likely to cause losses 
of coniferous nursery stock in the United States: 

(1) Sun scorch.—This is the commonest summer trouble. The 
roots die before or at the same time as the tops. Death is caused 
by excessive water loss. It usually occurs when the air is hot and 
dry and the soil around the roots is dry. The disease is worst on 
sandy soils, in crowded beds, and on raised parts of beds. On 
sandy soils it may kill suddenly and in definite patches. Successful 
preventive measures tested by the writer are watering, shading, and 
avoidance of crowding. In nurseries located on mineral soils the 
humus content should be increased. . 

(2) Wenterkilling.—The tops of the plants dry out when the soil 
is frozen so that the plants can not take up water. The preventive 
measures most used consist of a light straw mulch. on the beds and 
windbreaks. 3 

(3) Mulch injury.—The tops die in winter as a result of being 
mulched. This happens while the mulch is still on, or occasionally 


BLIGHTS OF CONIFEROUS NURSERY STOCK. 21 


just after it is removed. The roots do not die till some time after 
the tops. The immediate cause of death is unknown. The disease 
may be prevented by avoiding heavy, close mulches. Spraying with 
soap-Bordeaux mixture just before the beds are mulched in the fall 
may also be of value. | 

(4) Needle diseases—There are a number of needle-destroying 
fungi, some of which are certain sooner or later to cause damage in 
the nurseries in the more moist parts of the United States. They 
have so far done little damage in our nurseries and have been little 
studied. Spraying with Bordeaux mixture at the proper time will 
presumably prevent damage from any of them. The proper times for 
spraying are not yet known. The importation of European stock 
should be discouraged, in order to avoid bringing in parasites which 
have not yet reached this country. 

(5) Red-cedar blight—A great deal of blight occurs in red-cedar 
seedlings and transplants. The cause and methods of prevention 
are unknown. Shading, watering, and frequent spraying should be 
tested. 


2) 


WASHINGTON : GOVERNMENT PRINTING OFFICE : 1918 


| 
rae 


* 


Th ah 


4 ; 
x > 
= 
. 
Pac 
——— 
f r 
Bs | 
’ 
’ i 
> en ee 
7 
f ~ 
nf # 
y, 
/ 
t +5 
r 
em 
‘a ! fe 
5) Te, 5 : 
| 
a if 
4 we 
¥ a 
oT ase 
i ’ “= re 
P ov) } J 
yt! (4 wits 
as die Ca 
He 


Med 


BULLETIN OF THE 


0S.) USDEEIMENT OF AGRE 


No. 89 


Contribution from the Bureau of Plant Industry, Wm. A. Taylor, Chief. 
May 22, 1914. 


(PROFESSIONAL PAPER.) 


THE DEATH OF CHESTNUTS AND OAKS DUE TO 
ARMILLARIA MELLEA. 


By W. H. Lone, 
Forest Pathologist, Office of Investigations in Forest Pathology. 


INTRODUCTION. 


_ Some time ago complaint was made to the Office of Investigations 
in Forest Pathology that the chestnut trees on certain areas near New 
Berlin, in Chenango County, N. Y., were rapidly deteriorating; that 
some were dead, others dying, and the remainder in poor health. Since 
this region is not in the known range of the chestnut bark disease 
(Endothia parasitica), the dying of the chestnut could not be attrib- 
uted to this fungus, and the writer was therefore detailed to make an 
investigation of the trouble. 


CHARACTER OF THE TIMBER EXAMINED. 


Two areas of woodland of about 20 acres each were examined. 
The timber consisted of a mixed stand of chestnut, oak, and white 
pine, with a sprinkling of poplar, maple, and hemlock. All of the 
timber above a diameter of 6 inches, or even less, was being cut. 
Much of it had only recently been felled, while some was still uncut. 
The oak and chestnut were being made into railroad ties and the pine 
into lumber. Both tracts of timber were located on the level tops 
and slopes of rather rough ridges. The average age of the chestnut 
and oak was from 60 to 100 years. One of the areas had been partially 
logged over 20 years ago; the other had never been logged. There 
have been no forest fires in either tract,so far as known. As the 
two areas were close to each other and similarly located, they will 
be treated as a whole in this discussion. 


CHARACTER OF DATA OBTAINED. 


In addition to the felled trees of chestnut and oak, dead, dying, 
and badly diseased standing trees were studied. No attempt was 
made, on account of limited time, to examine the roots of any number 


Notr.—A record of the results of field investigations of the condition of chestnut and oak in Chenango 
County, N. Y. 


34907°—14——_1 


2 BULLETIN 89, U. S. DEPARTMENT OF AGRICULTURE. 


of living trees. A record was kept of each felled and each dead tree. 
The data taken included the diameter of stump, the average height of 
stump (which was usually about 1 foot), the diameter of the rot in the 
stump, the height to which the rot ascended in the butt of each tree, 
the cause of each kind of rot found, the root-rots present, the number 
of dead trees, the cause of death, the number of dead trees blown 
down, and any other facts bearing on the health of the trees. Data 
on 902 felled trees were obtained. Of this number, 477 were white 
oaks, 302 chestnuts, 61 red oaks, 45 poplars, and the remainder 
maples, service berries, and pines. 


GENERAL CONDITION OF THE CHESTNUT. 


HEALTH OF THE TREES. 


All of the chestnut trees over 18 inches in diameter were found to 
have diseased tops; that is, some were “‘stag headed,”’ while all had 
one or more large dead branches on them. Many of the larger 
chestnut trees, especially those somewhat isolated on the edges of 
the ridges, had been struck by lightning. These trees were not 
killed outright, but in many cases tops, branches, and strips of bark 
of varying sizes had been killed. In a few instances the bark had 
been partially stripped from the tree, but usually the lightning left 
little or no external evidence of immediate injury. A careful exam- 
ination, however, showed that wide strips of bark had been killed, 
especially near the bases of the trees, and that little or no callus had 
formed around the wounds. In the majority of cases the wounds — 
had not healed, but were gradually increasing in size. This increase 
was always greater at the base of the tree and could usually be traced 
directly to the parasitic action of the fungus Armillaria mellea. The 
typical rhizomorphs, or “‘shoe strings,” of this fungus were present 
at the bases of the trees and extended 5 to 20 feet upward beneath the 
bark. 

Of the tops, 75 per cent were infected by a pocketed or piped rot 
(Pl. I, fig. 1) caused by the fungus Polyporus pilotae, which had 
apparently entered through the old dead branches so common on - 
the upper parts of chestnut trees in this region. In addition to this 
top-rot, 46 per cent of the felled trees were infected with butt-rot, 
the bulk of which was also caused by Polyporus pilotae. 


RATE OF GROWTH. 


The chestnut bark disease was not found in the region examined, 
but the chestnut trees, and also the oaks and poplars, were undoubt- 
edly dying here and there from other causes. The annual rings 
in the chestnuts show that these trees had made a fairly rapid and 
vigorous growth during the first 20 or 30 years; then came a period 
~ of much slower growth, culminating in a period in which the annual 


Bul, 89, U. S. Dept. of Agriculture. PLATE I. 


Fic. 1.—HEART-ROT IN CHESTNUT CAUSED BY POLYPORUS PILOTAE. 


The fungus entered at the dead branch and has moved downward into the heartwood of the 
tree proper. 


Fic. 2.—“SHOE STRINGS” OF ARMILLARIA MELLEA BENEATH THE BARK OF A FELLED 
CHESTNUT WHICH HAD BEEN KILLED BY THIS FUNGUS. 


Bul. 89, U. S. Dept. of Agriculture. PLATE II. 


Fic. 1.—‘SHOE STRINGS” OF ARMILLARIA MELLEA ON THE. DEAD 
ROOTS OF A WIND-THROWN WHITE OAK. 


Fia. 2.—ARMILLARIA MELLEA UNDER THE BARK OF TWO CHESTNUT 
TREES WHICH ARE JOINED AT THE GROUND. 
The fungus has killed the tree in the foreground and has passed over to 


the other tree, where it has killed the bark for a distance of 8 feet up- 
ward and about one-third of the distance around the base of the tree. 


4 DEATH OF CHESTNUTS AND OAKS. 3 


increment was less than 1 millimeter in radius. In those trees 
which had been killed the annual increment in radius for the last 
6 to 10 years of their life was only one-third to one-fourth of a milli- 
meter. The average rate of increment was found to be 25 milli- 
- meters in diameter for 74 years of growth. This small increment 
indicates that the chestnut in this region is growing under very 
unfavorable conditions. 

A clearer idea of how slowly these chestnuts have grown can be 
obtained by comparing the diameters of a few of these trees with 
those of chestnuts grown under more favorable conditions in other 
localities. For this purpose data are used which were published in 
1905 by the Bureau of Forestry in Bulletin 53, entitled ‘The 
Chestnut in Southern Maryland,” by Raphael Zon. The Forest 
Service has permitted the writer to use some unpublished data con- 
sisting of growth-diameter measurements made in West Virginia and 
Tennessee by Walter Mulford in 1905-6 and in Hyde Park, Dutchess 
County, N. Y., by J. G. Peters in 1905. The data from Hyde Park, 
where the growth conditions for chestnuts were favorable, are espe- 
cially valuable for comparing with the growth data of chestnuts in 
_ New Berlin, as the two localities are in the same State. The growth 
- data of chestnuts grown in Connecticut, included in Table I, were 
_ obtained by compiling the figures contained in Bulletin 154 of the 
Connecticut Agricultural Experiment Station, entitled “Chestnut 
in Connecticut and the Improvement of the Woodlot,” by Austin F. 
- Hawes. 


Taste Y.—Diameter measurements and average ages of chestnut trees. 


DIAMETER, BREAST HIGH (INCHES). 


ay 
New York. 
; Connecti-| Mary- | Tennes- West 
Age and diameter. New. Hyde cut. land. see. Virginia. 
Berlin. Park. 
Age (years): 
eer eo A EE er ea 1.6 SS ok bet St otto 0.7 0.5 
eer? or 82 le Soc et cae eveee- 3.7 4.9 3.4 6. 67 3.1 2.4 
NR ee Oo oie a bn don t's oe 5.7 1.2 6.4 9.25 5.6 4.3 
2 Ue See ee eee 7.6 9.4 9.5 11.5 8.2 6.4 
Cn a UR reed 8.3 11.4 12.6 13.4 11.2 8.4 
Meee ees oe FE ble See 9.5 12.9 15.6 15.2 13.7 10. 4 
EEE de ee Sn wale Dob ae Se 10.7 14.0 18.7 17.3 16.0 15 
oo dae SS ES Se ee oe AU eee eee 21.7 18.1 18. 4 14. 4 
nbd bE SE ee eee Oe NCS ee ee 24.8 19.1 20. 3 16.3 
AMEE OL Joes ease bolls BLS aps 2 Fee oe 27.8 20. 0 21,7 18.2 
TO a LE ee AS a ee eae CU) fh (pages ak al 22.7 19.9 
AGE (YEARS). 
_ Diameter, breast high (inches): 
PMN Seo 5 ce piste ncdinceuesscas2ec 32 25 29 17 32 38 
Stok LA ae SaaS er ee ee 46 31 35 25 39 48 
EEE te ee aucieioiss obec. -cecescc'e = 56 38 39 29 44 53 
eG es a See ee oe 65 43 42 33 46 59 
gh 2 SE eee ere 80 47 45 38 49 63 
ES Se ES aS Se a 90 54 48 43 53 67 


4 BULLETIN 89, U. S. DEPARTMENT OF AGRICULTURE, 


From Table I it is readily seen that the chestnut at New Berlin, 
N. Y., has made a much slower growth than the trees from any bd 
the other localities listed. 


GENERAL CONDITION OF THE WHITE OAK. 


Of the oaks in this region, the white oak (Quercus alba) predomi- 
nates, but is intermixed with the red oak (Q. rubra). The tops of all 
the oaks appeared healthy, no “‘stag heads” or large dead branches 
being present. There was very little butt-rot of any kind in the boles. 
This was especially true of the area that had never been logged. In 
this area there occurred only 5 per cent of butt-rot and no top-rot of 
any kind. On the area which had been partially logged once there 
was a greater percentage of butt-rot due to injury to the standing 
timber from bruises on the roots and butts of the trees exposed to 
injury in logging. On this area the oak had 21 per cent of butt-rot, 
as against 5 per cent on the unlogged tract. Of this butt-rot, 87 per 
cent was caused by Hydnum ervnaceus, which by decay makes hollows 
and is capable of entering through slight bruises on the trees, as well 
as through fire scars and other deep wounds. 


ARMILLARIA MELLEA ON CHESTNUTS, OAKS, AND POPLARS. 


The ‘‘shoe strings’’ of Armillaria mellea were found very abundantly 
on the roots and under the bark of the butts of chestnuts, oaks, and 
poplars. They were also occasionally found on maples and on service 
berries (Amelanchier sp.), but none were found on the white pine. 
These ‘‘shoe strings”’ were also common in the soil around the bases of 
the diseased and dead trees. On some of the dead chestnut trees 
these ‘‘shoe strings’? had grown upward under the bark for 15 or 20 
feet. In many instances they had made a perfect network of strings 
over the sapwood (Pl. I, fig. 2). There could be no reasonable doubt 
that this fungus was killing the chestnut and oak, since trees were 
found in all stages of decline when it was present. Wherever a 
dead piece of bark on the base of a tree was removed, the brown or 
black rhizomorphs of this parasite were found beneath it. In such 
cases a watery zone of dying bark of a dark-brown color marked the 
boundary line between sound and diseased tissue. Sometimes only a 
very small area of the bark was affected, although the roots on this 
side of the tree were already dead and the outer layers of the sap- 
wood were more or less decayed. The rotten sapwood is watery, 
white in color, soft, and easily broken. On a chestnut tree 18 inches 
in diameter this fungus had killed an area 14 inches wide at the 
ground and extending 15 feet upward, while the “shoe strings” had 
grown up under the bark a distance of 8 feet. The top of this tree 
was dead. In three instances where chestnut trees had been struck 


~ ee oe 
vr ’ 


OLE ae ee Eee eae es ee ee eee ee ea ON 
: ; ‘ . 


“] 
Wy 
i 
= 
¢ 
hi 


DEATH OF CHESTNUTS AND OAKS. 5 


by lightning this disease was found following up and enlarging the 
wounds. Many of the white oaks killed by this fungus had been 
blown down. In every case the upturned roots were covered with a 
network of the black rhizomorphs (PI. II, fig. 1). Several groups of 
two to four chestnut trees which had originated from sprouts around 
a common stump were found killed by this root-rot. Plate II, figure 
2, shows two trees from a common base, one being already dead 
and the other badly diseased. In the latter the bark and roots on 
the side adjacent to the dead tree were killed for about one-third of 
the distance around the base, and the rot had extended up the tree 


‘8 feet under the bark. 


PERCENTAGE AND SIZE OF CHESTNUTS KILLED BY ARMILLARIA MELLEA. 


Of the 302 felled chestnut trees examined, 64, or 21 per cent, had 
been killed by the Armillaria root-rot. The average diameter of these 
killed trees was 12 inches; the largest chestnut killed was 26 inches 
and the smallest 3 inches in diameter. Trees of all diameters be- 
tween these limits were found diseased and killed. Of these trees, 
10 had a diameter of 3 to 5 inches, 13 of 6 to 10 inches, 22 of 11 to 
15 inches, and 19 of 16 to 26 inches. From this it follows that a 
greater percentage of the large chestnut trees was killed by this root- 
rot than of the smaller and younger trees. Of the 64 chestnut trees 
killed, 41, or 64 per cent, were over 10 inches in diameter. The 
average diameter of these 41 trees was 16 inches. In the white oak, 
just the reverse occurred; a greater. percentage of the smaller and 
younger trees was killed than of the larger and older ones. 


PERCENTAGE AND SIZE OF OAKS KILLED BY ARMILLARIA MELLEA. 


Of the 477 oaks checked, 130, or 27 per cent, had been killed by 


the Armillaria root-rot. The average diameter of these killed trees 


was 7 inches, as compared with 12 inches in the chestnut. The 


largest oak killed was 18 inches and the smallest 2 inches in diameter. 
_ Trees of all sizes between these two extremes were affected. Of 


these white oaks, 39 ranged in diameter from 2 to 5inches, 70 from 6 to 
10 inches, and 20 from 11 to 15 inches, with only 1 over 15 inches. 
Of these 130 white oaks which had been killed, 84 per cent were less 
than 11 inches in diameter and only 16 per cent were over 10 inches 
in diameter, as compared with 64 per cent in the case of the dead 
chestnut trees in the same locality. | 
Of the white oaks killed by this root-rot, 46 had been overthrown 
by the wind, while only 2 of the dead chestnuts had been blown 
down. Of the wind-thrown oaks, 26 were from 6 to 8 inches in 
diameter, showing that the smaller as well as the larger sizes of white 
oaks were not as easily uprooted as those of medium diameter. 
34907°—14——_2 


6 BULLETIN 89, U. S. DEPARTMENT OF AGRICULTURE. 
NUMBER AND SIZE OF POPLAR TREES KILLED BY ARMILLARIA MELLEA. 


In addition to the dead chestnuts and oaks, the writer counted 29 
poplar trees which had been killed by this root-rot out of a total 
of 45 examined. Many of these were small and much suppressed, 
although there were 12 that ranged from 6 to 9 inches in diameter. 
These larger poplars were not suppressed and under normal condi- 
tions ought not to have died. 


GENERAL DISCUSSION OF THE DISEASED CHESTNUTS AND OAKS. 


Why a larger percentage of small white oaks should be killed than 
of small chestnut trees is difficult to explain from the ‘data at hand. 
However, it seems to be evident, judging from the location of the 
smaller white oaks which were killed, that the majority of the trees 
under 11 inches in diameter were much suppressed and for this reason 
would perhaps succumb more quickly to disease than trees growing 
under more favorable conditions. Nothing was found to indicate that 
the larger white oaks which had been killed were in poor health 
before they were attacked by this disease. It would seem that the 
disease, having gained a foothold in the soil, simply spread to the 
large white oaks and finally killed them. As far as could be deter- 
mined, the fungus Armillaria mellea was the primary cause of their 
death. No white oaks in this region were seen which had been 
struck by lightning; this was in marked contrast to the number of 
chestnut trees in the same territory which had been struck. 

The only explanation which can be offered for the small percentage 
ef young chestnut trees which had been killed by the root-rot is that 
the present stand of chestnuts originated mainly from sprouts, and 
the young trees therefore had the large root system of the parent 
stump from which to draw nourishment. As a result, their growth 
would be very vigorous during the first 10 or 15 years of life. Under 
such conditions one would not expect a hemiparasite like Armillaria 
mellea to attack them as readily as it did the suppressed young oaks. — 
This, however, does not explain why the disease has killed so many — 
of the older and larger chestnut trees, unless the old stumps acted — 
as a breeding ground for the mycelium until it obtained a foothold 
in the living trees. The chestnuts undoubtedly were growing under 
unfavorable conditions, a fact proved by the very small annual inere- 
ment. This would make them more subject to diseases of this type. 
The weather conditions in the past may have been such as to weaken 
the trees and thus make them more susceptible to this rot. For 
instance, in the year 1913 the chestnut trees had lost two sets of leaves 
from late frosts, and at the time this investigation was made (June 
19, 1913) the third set of leaves was not fully developed, and many 
of the trees were so badly injured that they apparently were not 
going to leaf out at all. 


DEATH OF CHESTNUTS AND OAKS. t 


AREAS INFECTED BY ARMILLARIA MELLEA,. 


Ten distinct badly diseased areas of varying sizes were found in 
which the Armillaria root-rot had killed many trees. On one area 
40 yards in diameter, both chestnuts and oaks of large size had been 
killed, including 6 chestnuts with diameters of 8, 8, 10, 12, 14, and 
16 inches, and 4 oaks with diameters of 8, 13, 14, and 14 inches, re- 
spectively. Another rather large area had 34 dead trees scattered over 
it; of these there were 25 white oaks, 6 chestnuts, and 3 poplars. 
_ These trees ranged from 3 inches to 26 inches in diameter. On none 
of these diseased areas were all of the trees killed; some were alive 
and apparently in good health. This root-rot is aire was much 
“worse where the soil. was very damp, or even wet, during certain 
_ portions of the year. 

' Mr. H. M. Sears, of the Forest Service, in a report entitled “ Deteri- 
oration of Blight-Killed Chestnut in Nace New Jersey,” mentions 
_ the presence ‘of the rhizomorphs of Armillaria mellea beneath the 
_ bark of some of the dead chestnut trees. No evidence was advanced, 
= however, to show that this fungus had attacked the chestnut trees 
| before they died. 


ARMILLARIA MELLEA ON CHESTNUTS IN NORTH CAROLINA. 


3 
AREA EXAMINED 
~ On a recent trip through North Carolina, the writer found a rhizo- 
C3 morphic root-rot prevalent on the chestnut near Mount Airy, N. C., 
_ which is apparently the same as that found in New York. As the 
investigations in North*Carolina were devoted primarily to the heart- 
rots of trees, very little time was given to this root-rot problem. 
_ However, some data on the character and extent of the disease were 
taken. ‘The area studied was located about 6 miles east of Mount 
” Airy, near Brim, N. C. 


CHARACTER AND GENERAL CONDITION OF THE TIMBER. 


_ The timber was located on the ridges and slopes and consisted of 
a mixed stand of chestnut and oak growing in a rather thin, more or 
- less rocky soil with a red-clay subsoil. Chestnut oak (Quercus prinus) 
was the principal species of oak, but white oak (Q. alba), black oak 
r (Q. velutina), and red oak (Q. rubra) were also present. All of the 
_ chestnut over,the area examined was deteriorating, 90 per cent was 
_ stag headed and much was actually dying, while from 20 to 30 per 
a ‘cent was already dead. There was little or no sprout reproduction 
i _ from the bases of the affected trees. Because of the rotted condition 
of the roots, the dead and dying trees in this region are easily blown | 
down. According to resident millmen, this dying of the chestnut has 
_ become very pronounced during the last fifteen to twenty years. 


8 BULLETIN 89, U. S. DEPARTMENT OF AGRICULTURE. 


The chestnut over this area originated mainly from sonata and, 7 
judging from the large annual increment, it made a healthy and | 
vigorous growth aia: this trouble at a 


NUMBER AND CONDITION OF THE INDIVIDUAL TREES EXAMINED. 


The roots of 71 dead or badly diseased trees were examined. Of © 
this number, 64 were chestnuts, 5 black oaks, 1 a chestnut oak, and 1 | 
a sassafras. Of the chestnuts, 55 were already dead and 23 of them — 
had been blown down when the studies were made. This afforded | 
an. opportunity to examine the condition of the roots. Nine of the | 
living chestnuts studied were either dying or badly stag headed. | 
Chestnut trees of all sizes were found dead or dying. Of the 64 | 
chestnuts studied, 7 ranged in diameter from 4 to 10 inches, 23 from 
11 to 20 inches, 29 from 21 to 30 inches, and 5 had diameters greater © 
than 30 inches. An occasional black oak was found dead or badly © 
stag headed, especially when adjacent to the worst affected chestnuts. — 
The chestnut oaks, however, seemed to be vigorous and in the best — 
of health. Especially valuable data were obtained from a wind- 
thrown chestnut 38 inches in diameter, which had been living but 
was badly stag headed when blown down. ‘This tree was blown down — 
only 11 days before the data were taken. The condition of its roots © 
and stool was, therefore, exactly the same as when alive. When this | 
tree was overthrown, several of the most superficial roots were still 
alive, but all of the deeper roots were dead. The sapwood of the © 
dead roots was white rotted and covered with a network of black ~ 
rhizomorphic strands. This rot was gradually encroaching on the ~ 
living roots and killing them. The tree stood on the top of a rocky © 
red-clay ridge, with the bulk of its roots within 2 feet of the surface — 
of the soil. . 

All of the 71 trees examined had the ‘‘shoe strings”’ of Armillaria © 
mellea on their roots. They were also found in a few instances ex- 
tending from 3 to 8 feet upward beneath the bark on both living and ~ 
dead trees. As a rule, however, the rhizomorphs were inconspicuous 
and were confined mainly to the roots and stools of the affected trees. 
The area studied was very limited, and no attempt was made to 
examine the roots of a large number of living trees. The data given 
here are therefore too meager to justify any positive opinion as to the 
amount of damage done by this root-rot in North Carolina. How- 
ever, the prevalence and apparent destructiveness of this fungus over 
the area examined seem to point to it as very probably an important — 
factor in the gradual recession of the chestnut in that State. If such 
an organism is at work, it would in a large measure explain the 
hitherto unexplained phenomena associated with this recession, — 
such as the lack of reproduction from sprouts and the failure of the 
chestnut to reoccupy its former territory. A more extended investi- 


DEATH OF CHESTNUTS AND OAKS. 9 


gation covering the entire range of this recession may or may not 


show the presence of this root-rot as abundantly over the other 


regions involved as it is at Brim. The identification of this root- 
rotting organism as it occurred both in New York and in North 
Carolina was made from the rhizomorphic strands present on the 


affected trees. No sporophores were found, as the time of the year 


_ during which the diseased trees were examined was not the proper 


season for their appearance. 
CONCLUSIONS. 
(1) The chestnut near New Berlin, N. Y., and at Brim, N. C., is 


_ deteriorating. This is clearly shown by the small annual increment 
_ during recent years, by the thin sapwood, by the large percentage of 


| 


diseased and stag-headed tops, and by the number of dead and dying 


trees. This decline is probably due to several factors, one of which 
is the root-rotting fungus Armillaria mellea, but it should be noted 
that in spite of these facts the chestnut bark disease (Endothia para- 
sitica) is not present in these localities. 

(2) Armillaria mellea can become an active parasite under favor- 
able conditions, especially in chestnuts and oaks, killing not only 
suppressed trees in the forest, but also those that are growing under 


more favorable environments. 


(3) The prevalence and apparent destructiveness of this fungus 
over the area examined in North Carolina seem to point to it as very 


_ probably an important factor in the gradual recession of the chestnut 
in that State. 


» 


O 


a vs i ; y “A ; ah yh 


Ce RES a ats roi bert ‘eit hy Pe i 3 @: SHR 
f vie id yb as “Et ae ha ass OSA Sth im 
ane Cart a eA Ora Ne Pres os bes ‘Stee pert ae bas 
Bee, eh Poti Mok geek rd font, Pig CHAE aR st bp 
EE 83 FRSA. FARE GS ay erta te bene Ay ibys ‘vas 
ot eae sretht. kd ea fy ain Fane pe reate aE Hy) ne y 
raengen ey ots Reh Leaner "OO Se 241038 eee vad 

est Pints ated faite 


F Cayce 
" : e ‘ , v 


Fete sas ee ot Bis xe y 4 Bios 


mee sh Dea, FP eee 
*! CED cS Nae sae est ait oan 
AGE Sis PARE CV eae et ae ee ae 


PP Ey rt ee oth Pertig= ceataj2 hatiae 
et { ad ater ? Ba gS Nid ay et § + AD 


~ 
~” 

» 

w* 
4 

e 
ght 
quan 
ee 
: S34 
rT 
s 


bah " ee ae 


PT IOR os 18 3 a fers 
q 4 5 an - 
ont 2. a Siiessin » MG piphy bon 
M nc is Bipeetr tivigeh 3 Fea ite 
- {a is : 
{i ¥ t, Cone e 
il . ays heh - 

‘ je 
wi “ Ke os: 
stares ah? 

~ : pes. 
—_ 27] + Agee y 
By i “4 r A 
ae i I : 
) 
, 7 - +* 
~ : rahi er = 
‘ ¥ + Bhs ‘ye 
a tii +) bs é 
“f 


te 


fay at 


hes nae ¥ 


hy 


~ 


BULLETIN -OF THE 


€ 5) sven MRE & J 


No. 116 


Contribution from the Bureau of Plant Industry, Wm. A. Taylor, Chief. 
June 24, 1914. 


(PROFESSIONAL PAPER.) 
NEW FACTS CONCERNING THE WHITE-PINE BLISTER RUST.* 


By PerRtEy SPAULDING, 


Pathological Inspector, Federal Horticultural Board (formerly Pathologist, Office of 
Investigations in Forest Pathology). 


INTRODUCTION. 


In a, recent publication? the writer gave the latest information 
regarding the white-pine blister rust up to the spring of 1913. The 
past season has brought forth several additional developments, 
which are of great importance. 


THE SITUATION AT GENEVA. 


Since 1906, when Stewart first discovered the presence of Cronar- 
tium ribicola upon Ribes at Geneva, N. Y., the disease has been 
_ found there in several different years.2 This occurred in spite of the 
total destruction of the Ribes found affected in 1906 and the apparent 
absence of the ecial stage of the fungus on the neighboring white 
pines.» In the spring of 1913 the New York State department of 
agriculture took up the matter, and a special effort was made to 
locate and examine every white-pine tree within the diseased area, 
with the result that two trees about 15 years old were found by 
Inspector Maney bearing the fruiting bodies of the fungus. They 
' were promptly destroyed. These evidently had been diseased for 
_ along time, probably since they were 3 or 4 years old. No definite 


_1This paper is intended to supplement the previous publication, Bureau of Plant Industry Bulletin 
206, entitled ‘‘The Blister Rust of White Pine.” It is, therefore, as brief as possible, and care has been 


taken not to duplicate statements made in that publication. These two bulletins are necessary in order 


to secure complete information regarding this disease. 

2Spaulding, Perley. The present status of the white-pine blister rust. In U.S. Dept. Agr., Bur. Plant 
Indus. Cire. 129, p. 9-20, 6 fig. 1913. 

3 Stewart, F.C. Pine blister rust and currant felt rust. In West. N. Y. Hort. Soc. Proc. 58th Ann, 
Meeting, p. 122-124. 1912. 

Stewart, F.C., and Rankin, W. H. Can Cronartium ribicola overwinter on the currant? Jn Phyto- 
pathology, v.4,no.1,p.43. 1914. 

Jordan, W. H. Director’s report for 1906. N. Y. State Agr. Exp. Sta. Bul. 284, p. 341-342. 1906. 
Director’s report for 1912. N. Y. State Agr. Exp. Sta. Bul. 356, p. 559. 1912. 

NotEe.—This paper contains additional information concerning the white-pine blister rust that was 
collected during the season of 1913. It is ot interest to foresters, tree experts, nurserymen, and owners of 
ornamental and forest plantations of 5-leaved pines. 


45612°—Bull. 116—14 


2 BULLETIN 116, U. S. DEPARTMENT OF AGRICULTURE, 


information concerning their origm could be obtained, but it is 
believed that they were imported when 3 or 4 years old, that the 
disease came with them, and that they have been serving ever since 
as a center of infection each season for the Ribes in that vicinity. 
During the season of 1913 the disease appeared on but few Ribes 
bushes near the two trees above mentioned. The pines of the vicinity 
are to be held in quarantine and inspected each spring. Inspite of the 
recent pessimistic opinion of those most directly concerned in the mat- 
ter, there is every reason, to believe that the disease will soon be eradi- 
cated at this point, now that the center of infection is finally located. 
The conclusion that “complete eradication of the disease is no longer 
possible” is apparently meant to apply to the entire country and is 
based on the fact that blister rust was established at Geneva and the 
supposition that it was established in other places in New York, Mas- 
sachusetts, and Connecticut. Now that the disease is well in hand in 
the Geneva area (the most dangerous one known at that time in the 
entire country’), there seems to be no sufficient reason for giving up the 
fight against as dangerous a disease as this promises to become if 
unchecked. This is especially true in view of earlier statements as 
to the seriousness of this disease.’ 


NEW OUTBREAKS. 


Early in July the writer received specimens of white pine affected 
with blister rust from a point in northern Vermont which had not 
been previously known as harboring the disease. Inquiry showed 
that it was present upon. native trees in that vicinity, this being the 
first known instance in this country. A visit was immediately made 
to determine the facts in the case, and the disease was found in the 
ornamental plantings of a large private estate. The original source 
of infection is unknown. It is quite possible that a few imported 
white-pine trees were obtained years ago, although it is definitely 
known that most of the trees in the vicinity are native and grew in 
the near-by woods. At any rate, the disease has been in some of the 
trees about 10 years, judging from the location of the cankers and 
their general appearance. Of the total number of white-pine trees 
m that vicinity, about 150 in all, more than 50 were found to be 
visibly affected by the diseaSe. How many may later develop blister 
rust is, of course, unknown, but probably 5 or 10 per cent will do so. 
Already about 334 per cent have it, which should be sufficient to con- 
vince the occasional skeptic that this will be a serious disease * if 
allowed to run its course in this country. 
stract.) In Phytopathology, v.3, 0.1, p.73. 1913. 

2 Stewart, F. C., loc. cit. 
2 Stewart, F. C.,.loc. cit.; Jordan, W. H., loc. cit., 1912. 


4 Clinton, G. P.. Notes on plant diseases of Connecticut. In Conn. Agr. Exp. Sta. Rpt., 1909-10, p. 733. 
q9i1. 


WHITE-PINE BLISTER RUST. 3 


The disease had evidently reached a stage at this place where its 
future spread would be much more rapid than it has been in the past. 
About 100feetfrom the apparent original center of infection was a single 
black-currant bush (Ribes nigrum),! some 50 to 75 red-currant bushes 
(Ribes vulgare), and about 30 gooseberry bushes (fibes grossularia). 
The leaves of the black currant were covered with telia and uredinia 
of Cronartium ribicola, but only a very few sori were found on the 
red currants and none on the gooseberry leaves. Evidently the 
conditions have been extremely favorable for the propagation and 
spread of the fungus ever since the Ribes were set in that locality. 
All of the Ribes have been removed and destroyed, and the diseased 
trees and parts of trees are being cut out and destroyed. 

Late in the fall of 1912 the writer received a specimen of blister 
rust on leaves of Ribes from Ipswich, Mass. In the spring of 1913 
two small white pines which bore fruiting bodies of the fungus were 
found by the State nursery inspector near the diseased Ribes bushes. 
These were destroyed, and it was believed that the disease had been 
eradicated. It appeared later, however, about half a mile away, on 
leaves of Ribes nugrum and of Ribes vulgare of the variety Red Cross. 
The abundance of the fungus led the writer to suspect the center of 
infection to benear by. An examination promptly revealed evidences 
of the disease on neighboring white pines of about 10 and 18 years of 
age. Steps are being taken to remove the diseased trees and branches 
and also the black currants. 

In 1913 Clinton ? reported an owtbreak of this fungus on the leaves 
of black currants near Meriden, Conn., late in 1912. He examined 
the vicinity, but could find no infected white pines in that locality. 
The origin of this outbreak is still unknown, and for this reason the 
situation 1s perhaps more dangerous than that in any other locality 
where the disease is now known to occur. 


SERIOUSNESS OF THE DISEASE. 


In the Vermont locality mentioned one large white pine about 2 
feet in diameter and quite mature from the lumberman’s standpoint 
was found to have the disease scattered throughout the top. 
Branches of all sizes up to 4 inches in diameter were thus affected. 
From the condition of this tree it was very easy to understand how a 
large tree may be killed by very severe attacks of this fungus, since 
it is a mere matter of time before an attacked branch or tree trunk is 
killed above the point of infection. One tree about 20 years of age, 
which had been infected in the trunk about 10 feet from the ground, 


1 The three Ribes mentioned are cultivated species which have been introduced into this country from 
Europe. The last (Rives grossularia) is usually placed in a different subgenus than are the two first; by 
some authors it is placed in a separate genus. 

2Clinton,G.P. Notes on plant diseases of Connecticut. In tM Agr. Exp. Sta. Rpt., 1912, p. 347-348, 
1913. 


4 BULLETIN 116, U. S. DEPARTMENT OF AGRICULTURE. 


had its top entirely dead above that point. Numerous small branches 
were found on other trees in a similar condition. A number of other 
trees of the same age apparently have been killed in a similar way, 
as they have been dying for years and have had to be removed, one or 
two at a time. While it takes a long time for the destructiveness of 
this disease to reach its climax in any given locality, there can be no 
doubt that if it finally becomes established and generally distributed 
in our forests it will be the worst enemy the white pine has here, as is 
stated to be the case in certain European countries.:' It has become 
so thoroughly established in Europe that there is no hope of eradi- 
cating it there, but there is yet time to suppress it here if the danger is 
once generally realized. Even with conditions as they are in Europe, 
one of the most prominent plant pathologists of Germany recom- 
mends the energetic fighting of this disease. If such action is 
advisable in Europe, even more drastic action is certainly proper in 
this country. 


CAN THIS DISEASE WINTER OVER ON RIBES? 


Late in 1912 F. C. Stewart asked the writer to take part in a 
cooperative experiment to try to determine whether this disease can 
winter over on dormant Ribes stock and thus be carried from one 
place to another in stock which has previously been diseased. ‘Two 


hundred 2-year-cld Ribes nigrum plants which had been heavily — 


rusted by Cronartium ribicola in the late summer and early fall of 1912 
were sent to the writer at Washington, D. C., about December 1. 
They were promptly heeled in out of doors until February 1, when, 
according to agreement, they were potted and brought into the 
greenhouse. They started quickly and made a very vigorous growth. 
They were examined several times for the presence of Cronartium 
ribicola, but none was found. The experiment was concluded about 
May 20 because of the writer’s absence after that date. Parallel 
tests were made at Geneva and Ithaca, N. Y., Lafayette, Ind., 
Amherst, Mass., and New Haven, Conn., 300 plants being used.? 
The results were entirely negative. The evidence furnished by the 

1 Bos, J. Ritzema. Phytopathologisch laboratorium Willie Commelin Scholten. Verslag over de inlich- 
tingen gegeven in 1900. Jn Landbouwk. Tijdschr., jaar9,p.77. 1901. 

Fisher, W.R. Experimental plantations at Coopers Hill. Jn Quart. Jour. Forest., v. 3, no. 3, p. 229. 
1909. 

Fron, Georges. Nouvelles observations sur quelques maladies des jeunes plants de Coniféres. Jn Bul. 
Soc. Mycol. France, t. 27, no. 4, p. 476-481. 1911. 

Lind, Jens. Danish fungi as represented in the herbarium of E. Rostrup, p. 281-283. Copenhagen, 1913 

Neger, F. W. Die Nadelholzer ... p. 110-111. Leipzig, 1907. 

Somerville, W. Peridermium strobi, the blister of Weymouth pine. Jn Quart. Jour. Forest., v. 3, no. 3, 


p. 232-236. 1909. 
Watson,J.G. The Woburn forests. Jn Gard. Chron.,s. 3, v. 52,p.422. 1912. 


4Tubeuf,Carlvon. Uber die Verbreitung yon Baumkrankheiten beim Pflanzenhandel. Jn Mitt. Deut. - 


Dendrol. Gesell., p. 156-163, 1904. 
8 Stewart, F. C.,and Rankin, W. H. Can Cronartium ribicola overwinter on the currant? In Phyto- 
pathology, v. 4, no. 1, p. 43. 1914. 


WHITE-PINE BLISTER RUST. 5 


natural occurrence of the disease shows that dormant Ribes stock 
_ does not harbor the fungus. But all the evidence is negative (except 
that mentioned earlier by the writer)+ and is subject to certain 
_ limitations, as is all negative evidence, when general conclusions are 
drawn from it. That is, it does not effectually dispose of possible 
' rare exceptions, which may occur only once in thousands of cases. 
_ The practical conclusion is that Ribes plants do not carry the fungus 
- over winter and that an outbreak of this disease on Ribes is to be 
attributed to the presence of neighboring white pines which have 
_ the blister rust. Hence, when the disease is found on Ribes leaves a 
_ special effort should be made to locate and destroy infected trees.’ 
_ Ewert * has recently published a paper showing that thorough spray- 
ing with Bordeaux mixture, with special care to’ cover the lower 
_ surface of the leaves, will almost completely control this fungus upon 
 Ribes nigrum. lt is suggested that in the future when diseased pine 
trees are found early in the summer, any Ribes in the vicinity be 
_ promptly sprayed on both sides of the leaves, in order to reduce the 
_ resulting infections and the outbreak of the uredo stage. Spraying 
_ should not be resorted to except as a temporary expedient, as just 
indicated. 

_ About May 15, 1913, several plants of Ribes nigrum were isolated 
and an attempt was made to inoculate them with telial material 
furnished by Stewart which had been kept out of doors all winter. 
_ This attempt was unsuccessful, as was also a similar one made by 
the writer in 1912 with fresh teliospores. 


CULTIVATED VERSUS WILD RIBES. 


A statement has been made implying that the cultivated species 
of Ribes are not dangerous factors in connection with this disease.‘ 
All of our experience in this country shows that the contrary is true. 
In no known case has the disease been discovered on native wild 
_ species of Ribes, while it has been found in a number of cases on the 
- cultivated species of Ribes nigrum and Ribes vulgare. The evidence 


_ shows that our native wild Ribes cynosbati and Ribes prostratum are 


resistant to the fungus, while Ribes nigrum is exceedingly susceptible, 
and some varieties of Ribes vulgare are quite susceptible. The variety 
_ Red Cross has been found in one instance to be seriously diseased. 
 Ribes grossularia has been immune. The cultivated Ribes are much 


1 Spaulding, Perley. Notes upon Cronartium ribicola. Jn Science, n.s., v.35, no. 891, p. 146-147. 1912. 
The present status of the white-pine blister rust. Jn U.S. Dept. Agr., Bur. Plant Indus. Cire. 
129, p. 17. 1913. 

_  2S$paulding, Perley. Notes on the white-pine blister rust. (Abstract.) Jn Phytopathology, v. 4, no. 1, 
 -—p. 41-42. 1914. 

% 3Ewert,R. Erfolgreiche Bek’mpfung des Cronartium-Rostes auf der schwarzen Johannisbeere. In, 
__ -Ztschr. Pflanzenkrank., Bd. 23, Heft 8, p. 463-476, 2 fig. 1913. 

$ Clinton, G. P. Notes on plant diseases of Connecticut. In Conn. Agr. Exp. Sta. Rpt., 1909-10, p. 732 
1911. 


6 BULLETIN 116, U. S. DEPARTMENT OF AGRICULTURE. 


more dangerous than are the native wild plants, because many white- 
pine plantations are made on deserted farms. In such places the | 


former garden currants persist for years, and the inspector often 
finds them in the midst of a plantation of imported pines. Moreover, 
nurserymen often keep stocks of white pines and Ribes in proximity 
to each other, which is dangerous if either has the disease. These 
facts do not mean that wild species of Ribes can be disregarded, but 
that both wild and cultivated species must be considered when con- 
trol measures are undertaken. 


PINUS EXCELSA A HOST. 


In a recent publication Lind’ mentions the Himalayan pine (Pinus 
excelsa) as a known host of the white-pine blister rust in Denmark. 
The writer is informed that the disease was found in 1913 upon 


young trees of Pinus excelsa in Massachusetts. Unfortunately, no 


specimens of it were saved, but there seems to be no doubt that 
Pinus excelsa is a host of this fungus and is liable to be affected by it 
in this country. This is the first time that the white-pine blister 
rust has been found here on any other species of pine than Pinus 
strobus. 

AGE OF DISEASED WHITE-PINE TREES. 


White-pine trees from 3 to about 75 years old having the blister 
rust have been seen. From 3 to 15 years the series was almost unin- 
terrupted; then the ages were approximately 18, 20, 25, and 75 


years.. The trees of 25 and 75 years were diseased on the branches — 


and not on the main stem, but below 25 nearly all have been affected 
on the main stem. The evidence seems to show that this disease 
has been present on small numbers of imported pine trees in this 
country since 1888, and perhaps longer.? 


DISTRIBUTION OF SPORES OF CRONARTIUM RIBICOLA. 


In 1912 the writer made some observations on the distribution of 
the spores of Cronartuum comptonae from Pinus rigida to Comptoma 
asplenfolia The eciospores are so similar in size and shape to those 
of the blister rust on white pine that it seems probable that one would 
be distributed as far as the other under the same conditions. It was 
found that the esciospores of Cronartvuum comptoniae were blown 
about 30 feet from their point of origin. This led the writer to sus- 
pect that the eciospores of the white-pine blister rust would also be 
blown relatively short distances. Such has been the case in all those 


1Lind, Jens. Danish fungi as represented in the herbarium of E. Rostrup, p. 281-283. Copenhagen, — 


1913. 

2Spaulding, Perley. The blister rust of white pine. U.S. Dept. Agr., Bur. Plant Indus. Bul. 206, 
p. 36. 1911. 

3 Spaulding, Perley. Notes on Cronartium comptoniae. Jn Phytopathology, v. 3, no. 1, p. 62. 1913. 


WHITE-PINE BLISTER RUST. ay 


not so much in the total number of diseased trees present as it does 
- instances that the writer has had an opportunity to investigate per- 
sonally and where the origin of the spores has been determined. Two 
instances, on the other hand, where no diseased pies were found, 
seem to indicate that the sciospores were blown long distances, 
- though this is by no means a certainty. In the three instances exam- 
ined by the writer in 1913, the Ribes were about 100 feet from the 
diseased pines. There is every reason to believe that the uredo- 
spores of the white-pine blister rust may be blown half a mile or 
- more. 
GENERAL RESULTS OF INSPECTIONS. 

Some of the general results of the annual mspections made for the 
_ white-pine blister rust, beginning in 1909 and continued to the pres- 
ent time, are of interest. In the States north and east of Washington, 
2D. C., about 4,000,000 white pines are known to have been imported 
since 1900. Probably 500,000 more have been privately imported, 
- about which nothing is known, making a total of about 4,500,000 
trees imported into these States. Of this number 1,725,000 are 
known to have been destroyed before they reached the hands of pri- 
- yate individuals, leaving 2,775,000 which have been set out in lots 
- ranging from 500 to several hundred thousand trees. The number 
of such known lots is approximately 200. The inspection of these 
_ trees has varied much, some having been inspected once, some care- 
fully inspected for the first time in 1913, and still others carefully 
- inspected each year since the discovery of the disease on pines 
- in this country in 1909. The figures given in Table I cover only 
_ those plantations that have been continuously under inspection from 
_ the beginning. 


TaBLeE I.—Resulis of the continuous inspection of infected lots of white-pine trees. 


No. Item. Number. 


ODS ace Fat ta eee.) MR oi fates Leela Salona hide cidawokeme gar 910, 000 


1 

ES TCI DE ee ge deca Sed ee ee ee 8,177 
3 | Total trees found with fruiting bodies of the fungus (data available for but 560,000 trees). 938 
4 | Lots of trees inspected.-.-............ Ee ay x. ope eee ot ene Ae edlem aot la teeters 150 
neo Ol trees whereidisease was f0UNd .. 2.6 ia eck ewe ie bene ewe wn cece bccuecaces 88 
6 | Lots of trees where fruiting bodies of the fungus were found....................---------- 45 


In Table I, item 6 includes none of the lots counted in item 5, and 
_ the same is true of items 2 and 38. The same is also true of similar 
items in Table II. 

In considering these results it must be remembered that a single 
_ tree with fruiting bodies of the fungus and in proximity to a currant 
bush may start an epidemic of the disease which may continue for 
_ years and may spread over an area of several square miles. In fact, 
this is practically what happened at Geneva, N. Y. The danger lies 


a 1 Stewart, F. C., and Rankin, W.H. Cronartium ribicola and the proscription of Ribes nigrum. 
_ {Abstract.) In Phytopathology, v. 3,no.1, p. 73. 1913. 
: J 


A 


8 BULLETIN 116, U. S. DEPARTMENT OF AGRICULTURE. 


in their wideness of distribution. The fact that 938 trees bearing 
fruiting bodies of the fungus were found within a certain area is of 
no special significance unless we note that they were found in about 
thirty different localities which are scattered well over that entire 
area of thousands of square miles. Then we perceive that it is 
inevitable that the disease will become established in one or more of 
those localities unless efficient control measures are taken and faith- 
fully continued until the disease is eradicated. As already indicated, 
this is not being done everywhere. 


TaBLE II.—Resulis of inspections of 80 lots of infected white-pine trees. 


No. Ttem. Lots. 


1 | Trees found bearing fruiting bodies in 1910 and not afterwards.................--------------- 15 
2 | Trees found bearing fruiting bodies in 1911 and not in 1910 or 1912........................-.-- 3 
3 | Trees found bearing fruiting bodies one year and also each year afterwards.................-. 3 
4 | Trees bearing fruiting bodies not found at first, but which were discovered later.............. 5 
5 | Diseased trees found at first, but not in‘later years: :...5.-... 22-2. 2. s2e ee eee oe 21 
gf Diseased trees found continuously... ....5. - dee. 00+ emje de 6 <inc)3 - seo oe = eee 12 


Items 1 and 2 show that in one-fifth of the lots the inspector appar- 
ently removed all the trees bearing fruiting bodies of the fungus in a 
single year, but in every such case trees were found thereafter which 
were diseased, but did not bear the spores of the fungus. In asingle 
instance only, all of the diseased trees were apparently removed by the 
first inspection. Our experience to date decidedly discourages the 
idea that a single inspection is efficient in eradicating this disease. 
Item 5 apparently contradicts this statement, but these lots may 
easily have been cases where the inspector took everything showing 
any abnormality and reported it as suspicious, when the disease was 
really absent. 

In a previous paper! the writer mentioned the apparent effect of 
cool weather in regulating the formation of telia of Cronartiwm ribicola 
in the greenhouse at Washington. This experience has been repeated 
the present season. Apparently, farther north, where the nights are 
relatively cool, this inhibition does not occur, as telia were found in 
northern Vermont on July 23. 

In a recent publication,? which received limited distribution, the 
writer showed the inefficiency of inspection, except as a temporary 
expedient, in trying to eradicate this disease. The total destruction 
gf infected lots of white pines was urged as being the only safe course. 
This means a considerable present loss, which, however, will be very 
slight when compared with the loss that will result if the blister rust 
is allowed to become established and to spread. 


1Spaulding, Perley. Notes upon Cronartium ribicola. Jn Science, n.s., Vv. 35, no. 891,p. 146-147. 1912. 
2 Spaulding, Perley. The present status of the white-pine blisterrust. In U.S. Dept. Agr., Bur. Plant 
Indus. Cire 129, p. 9-20, 6 fig. 1913. 


WASHINGTON : GOVERNMENT PRINTING OFFICH: 1914 


BULLETIN OF THE 


€B) USDEPARNENT OFAC 


No. 169 


ia A 
Ve: 
ha 7 


OZ 


Contribution from the Bureau of Plant Industry, Wm. A. Taylor, Chief. 
February 20, 1915. 


PROFESSIONAL PAPER. 


INJURY BY DISINFECTANTS TO SEEDS AND ROOTS IN SANDY 
SOILS. 


By Cart Hartizy, Pathologist, Investigations in Forest Pathology. 
INTRODUCTION. 


For several seasons the writer has conducted experiments in the 
application of disinfectants to pine seed beds for the purpose of con- 
trolling damping-off. Formaldehyde and various imorganic acids 
and salts have been tested. The work conducted at two of the 
nurseries with seed beds sown in the spring and summer has now 
been completed. The practical results of the disease-control work 
have already been briefly summarized.’ Because of the interest of 
soil investigators as well as plant pathologists in the behavior of dis- 
infecting agents in the soil, the data on injury to pine and weed 
seedlings by disinfectants are here published separately. Data on 
the effects of the disinfectants on the growth rate of pine seedlings 
are still being gathered from three nurseries, and it is hoped to pub- 
lish these later. 
_ Acknowledgments are due Dr. F. K. Cameron and others, of the 
Bureau of Soils, and Drs. Rodney H. True and F. D. Heald, of the 
Bureau of Plant Industry, for helpful suggestions. 


SOIL CHARACTERS. 


The nursery where most of the work was done is at Halsey, Nebr., 
in a valley among sand hills. The soil throughout the nursery area 
‘is quite uniform, both soil and subsoil being classed as fine sand. 
There is a fair amount of humus in the upper 10 to 12 inches, in some 
places extending to nearly 20 inches below the surface. Below 12 
inches there is no humus in most of the nursery. The soil at the 
other nursery, that of the Pennsylvania Railroad, near Morrisville, 
Pa., is.a light-gray sandy loam, with a fine, reddish, sandy subsoil 
which is rather nearer the surface than the subsoil at Halsey. Exami- 


1 Hartley, Carl, and Merrill, T.C. Preliminary tests of disinfectants in controlling damping-off in vari- 
_ ous nursery soils. In Phytopathology, v. 4, no. 2, p. 89-92, 1914. 


: 71222°—Bull. 169—15——1 


2 BULLETIN 169, U. S. DEPARTMENT OF AGRICULTURE. 


nation by the Bureau of Soils of the United States Department of — 


Agriculture shows the presence of the usual soil-forming minerals. 
The chemical and mechanical analyses are given in Table I. 2 


TaBLE I.—Chemical and mechanical analyses of the nursery soils at Halsey, Nebr., and . 
Morrisville, Pa. 


[The soil samples were taken from the upper 6 inches; subsoil from depths of 15 inches at Halsey and 12 
inches at Morrisville.) “ 


. Percentage of soil. i of sub- - 
Analyses. 
Morris- Morris- 
Halsey ilie: Halsey. ville. 
Chemical constituents: 

NO’ 6s S20 et A eV) ee 0. 24 0. 21 0.1 0.19 | 
P6gO 8 iece so. ebb da bcc ce, Lb aeeeoue les aa eee 3.08 1.60 2. 85 1.30 
AMjOg. Sats. sees SeL. eS Seek oye eee eee 14. 93 8.72 14.95 6.20 

gO Soe ees eit bs Sousd Coes Aletta en ERE 4. 48 1.68 . 80 1.88 _ 
POs. vce sks. - 0 chicas os Sede e sees eee eae eee Trace. Trace. 48 mS 

BO Hes isco. oak Scere ae cake | Seba eee ae eens . 86 2. 23 3.79 1.35 
Total salta by bridgect £.5- -§ UA OEE a ree ea. SERRE ee 21 39 09 - 08 

oS ape RP = eid eee eg Se Cte 6 See I tale 07 03 09 -05 
GOs, (from carbonates) !~ 0. 22). As. Ses a ee None. None. None. None. 
Ignition loss (two determinations averaged) .-....-----.---.. 2.41 2.93 55 1.96 
Lime requirements (CaO) per acre...........-..-- pounds. . 2, 450 1, 750 2,450 1,750 

Mechanical constituents (size of particles): 
Fine pravely2 tel wmimice ft i232 2s See SE eek 0 1.0 0 0.5 
Coarse sand, 1to OS: mm Sc. 29-2 oo. etree Seer seicee ee 3.0 10.9 3.5 8.6 
Medium sand)/055 100/25 mm... 3220s. 2ibs. Be eet 9.5 16.1 15.4 13.4 
Hine sand, 0.25 tot mn. eee ee So. oe Seek ecb aees 58.1 28.9 61.3 30.5 
Very fine'sand, 0:1:to0.0b'mim -.... 2228 - 2 ae ira ee 21.0 19.2 17.5 23.5 
Silt, 0.05:to 0.005 MBL. 22st -2 S- Se peea bes Ce eee eee ee 6.5 18.5 1.5 18.1 
Clay; 00054anmjand fimers= 525. S20 2. - 52/5 eee teeter ee 2.1 5.5 .8 - 6.2 


The wilting coefficient, determined by the indirect method of Briggs 
and Shantz,! was 3.42 per cent for the surface soil and 1.5 per cent 
for the subsoil at Halsey, and 4.92 per cent for the surface soil and 


4.73 per cent for the subsoil at Morrisville. The samples examined ~ 


from Halsey were taken from 10 different points in the nursery, 
while the samples from Morrisville represent three different points. 


EXPERIMENTS AT HALSEY, NEBR. 


Experiments at the nursery at Halsey have been carried on in 
cooperation with the United States Forest Service during the past 
five years. Mr. Robert D. Rands assisted the writer during the year 
in which most of the data were secured, and Messrs. R. G. Pierce and. 
Fred R. Johnson, of the Forest Service, rendered material assistance 


in the work. 
DISINFECTANTS USED. 


mtn 


i 


“p< te 


Minos, ag ST ett ee cs Ue. 


Pt dt 


Part of the sulphuric acid used in the following experiments was — 


C. P. (chemically pure), but most of it was a clear commercial grade, 
the acid used in most of the work here reported having a specific 


gravity of 1.84 and that used for the latest work a specific gravity of — 


1 Briggs, L. J., and Shantz, H. L. The wilting coefficient for different plants and its indirect determi- 
nation, U.S, Department of Agriculture, Bureau of Plant Industry Bulletin 230, 1912. 


—— 


INJURY BY DISINFECTANTS TO SEEDS AND ROOTS. 3 


1.83. Repeated parallel tests of C. P. and commercial sulphuric acid 
failed to develop any difference in their effect on the seed beds. A 
part of the hydrochloric and nitric acids used was C. P. and part com- 
mercial. The ammonia used was the strongest commercial ammonia 
water obtainable from local druggists (ordinarily 26° Beaumé). The 
formaldehyde used was the so-called 40 per cent commercial solution. 
_ Because of the need of distinguishing between pure formaldehyde and 
this commercial solution the latter will be referred to as formalin. 
The general use of the term ‘‘formalin”’ for the commercial solution 
_ appears to have become approved by custom,’ despite the fact that 
_ this term formerly applied only to the product of an English firm. 
The lime-sulphur used was a commercial solution with a specific 
gravity of 1.31. The mercuric chlorid used was C. P. and the cupric 
sulphate was the fully hydrated crystalline form. The copper acetate 
‘was neutral, containing a single molecule of crystallization water. 
_ The zine chlorid was a technical grade, granular, guaranteed from 95 
to 98 per cent pure. All lime used was air-slaked. 
The unit of measure used throughout is the fluid ounce (29.574 c. ¢.) 
+ for the acids, formalin, ammonia, and lime-sulphur solution, and the 
_ ayoirdupois ounce (28.35 grams) for the other substances. Except 
_ where otherwise stated, all of the disinfectants were applied in aqueous 
solution. When lime was used the powder was spread dry on the 
_ surface of the bed and was worked into the upper 2 or 3 inches with 
- arake. ‘Two or three pints of water per square foot of seed bed was 
_ found a convenient vehicle for applying the disinfectants. Because 
_ of the variable moisture content of the soil the degree of dilution of 
the solution before application is not of the greatest significance. 
_ The amount of the disinfectant used per square foot of soil surface 
is given in all cases as the measure of the strength of the treatment. 


PLANTS UPON WHICH OBSERVATIONS WERE MADE. 


The seed beds on which disinfectants were used were sown with 
different species of pine. Jack pine (Pinus divaricata) was the species 
used in most of the work, while western yellow pine (P. ponderosa), 
_ Norway pine (P. reswnosa), and Corsican pine (P. laricio) were also 
_ used, the relative frequency being in the order named. 

Weeds of various types appeared in the seed beds in addition to 
_ the pines, and data as to their tolerance of disinfectants were also 
obtained. Cryptogams were represented by a large-stalked species of 
_ Equisetum, the alge conspicuous in many nurseries being present to 
but a slight extent. Monocotyledons were represented by various 
grasses, Hragrostis cilianensis ? being much the most common, while 
_ Echinochloa crus-galli, Panicum barbipulvinatum,? and Chaetochloa 
1Perkin, W. H., and Kipping, F. 8. Organic chemistry, new ed., p. 124. London, 1911. See also 


_ Webster’s New International Dictionary, 1913. 
2 Determinations made by Mr. P. L. Ricker. 


4 - BULLETIN 169, U. S. DEPARTMENT OF AGRICULTURE. 


viridis 1 were also more or less common. The nurserymen pulled up 
most of the weeds before flowering, so that it was not possible to 
determine positively the relative frequency of the different grass 
species for each plat. The commonest dicotyledons were Mollugo 
verticillata,'! Portulaca oleracea, Amaranthus retroflecus,! A. hybridus,! 
A. graecizans,! A. blitoides,' and Euphorbia glyptosperma. 


INJURY TO PINES BY SULPHURIC ACID APPLIED AT OR AFTER GERMINATION. 


In the following cases sulphuric acid was applied to the beds after 
some pine seedlings had come up. Because of the great irregularity 
of germination in many beds the time of germination can be given 
only approximately. It represents as far as possible the date by 
which enough seedlings had appeared to constitute a fair stand. 
Most of the experimental plats were sown with jack pine. The 
results with this species appear in Table IT. 


TaBLE II.—Effect of sulphuric acid on seedlings of jack pine, at Halsey, Nebr. 


Fluid 
oe of , ounce of | volumes 
Time of treatment. acid per Result. 
plats siiaes of water. 
treated. Bot. 
On date of germination..........02....¢....- 0.172 : 
4 116 days after germination... - <-<tine <em> otek . 086 \ 128 | All killed. 
On yiagete eS ee ho Aes cape 2 - 086 
6 days after germination..................... . 043 : 
2 l)s days after germination..................... . 043 | 256 | Nearly all killed. 
13 days after germination................... . 043 
4/1 ap after germination: ...25.2.2....205..i0. - 086 128 | Many killed. 
SP ee See ee 2 ae ee 22 - 043 ; 
3 Paved after germination: . . ./252..-.\./-0. ose. . 043 ; A 
6 days after germination.................--.- . 086 256 pes art tbe in preceding 
8 days after germination....................- - 043 re g 
i eeye ates gen ieyon ns gible ce n> dine oun . 043 
n date of germination..........-..-.-...-.- . 021 hal pane 
2 2 days after germination Fg ae 021 512 Germination, 11.8 per cent. 
n date of germination.) 3.2% - 2. St. ee -O11 oes 
ses days after germination...................-- . O11 1,024 Cone: 13.8 per cent. 
BUNGEE S. Diss CL Pee oe eee eRe Noneti|:. o/c Germination, 14.7 per cent 


Half of the plats in Table II which were given the stronger solu- 
tions were sprinkled lightly with water immediately after each treat- 
ment. This watering had no evident effect in the plats treated with 
the 128-volume solution, but in four plats which received the 256- 
volume solution, followed by sprinkling, the stand of seedlings was 
more than twice as great as on four ad) acent plats which were given 
the acid treatment only. 

The results in the plats treated tity. the 512-volume solution 
indicate that a total of 0.043 ounce of acid per square foot applied 
before germination was complete was sufficient to prevent the appear- 
ance of some of the latest germinating seedlings, while 0.021 ounce 
in two applications had little or no effect. Further tests would be 
necessary to prove that injury can be caused by these very weak 
treatments. 


1 Determinations made by Mr. P. L. Ricker. 


Pn a —T nine 
PE AR AS im be ERTS 


.. Tabet. Gris eee, a 


INJURY BY DISINFECTANTS TO SEEDS AND ROOTS. 5 


Acid was also used after germination on seed beds of western 
yellow pine. In the first test the percentage of the seedlings which 
died during the first 33 days after germination was determined for 
four plats, as follows: 

Plat VIII-A.—On the twelfth day after germination, 0.086 ounce of acid in 128 
volumes of water; repeated on the fourteenth and nineteenth days. Loss, 72 per cent. 

Plat VIII.—Same acid treatment as VIII-A, but sprinkled lightly with water after 
each application. Loss, 33 per cent. 

Plat 27.—On the sixth and sixteenth days after germination, 0.086 ounces of acid; 
12, 14, and 19 days after germination, 0.043 ounce of acid; solution in 256 volumes of 
water. Loss, 21 per cent. ; 

Plat 28.—No treatment. Loss, 23 per cent. 


While the loss in plat 27 was slightly less than that in the untreated 
plat there is clear evidence that the acid killed the seedlings, as the 
parasitic loss in this plat was very much less than in the untreated 
plat. 3 : 
The treatments on Plats VIII and VILI-A were practically dupli- 
cated on a seed bed 13 days younger, with the result that the losses 
for the first 20 days were 45 and 47 per cent, respectively, as com- 
pared with 16 per cent in the nearest check. 

Further tests of sulphuric acid on germinating yellow pine were 
made during the two following seasons. In the first case, acid in 
256 volumes of water was tested on beds which had received 0.188 
ounce of formalin per square foot 40 days before sowing, a treat- 
ment which in itself had no appreciable influence. The results were 
as follows: 

Plat 402-S.—Seven and again twenty-five days after germination, 0.125 ounce of 

acid. Germination, 64 per cent; loss after germination, 44 per cent. 

Plat 402-N.—Seven days after germination, 0.125 ounce of acid. Germination, 51 


per cent; loss, 30 per cent. 
Check plat.—No acid. Germination, 68 per cent; loss, 62 per cent. 


In this series, the effect of the acid was clearly to prevent the 
_ appearance of the latest germinating seedlings and to kill the young- 
est seedlings which had already broken through the soil. The heavier 
loss in the untreated plats is due to heavy parasitism, which the 
acid treatment almost entirely prevented. 

_ The following season, using a solution of one part in 256 volumes 
_ of water, the following amounts of acid were applied to yellow-pine 
_ plats: 0.047 ounce per square foot on two plats three days after ger- 
mination; the same amount on two other plats six days after germi- 
- nation; and 0.063 ounce on three plats seven days after germination, 
_ No noticeable injury occurred, though counts of the seedlings indicate 
_ that a few were probably killed by the acid. 

Most or all of the injury caused by applications after the begin- 
_ ning of germination was due to injury to the roots. The light sprin- 
_ kling with water just after acid applications, which in a number of 


6 BULLETIN 169, U. S. DEPARTMENT OF AGRICULTURE. 


cases resulted in lessening injury, presumably exerted its effect 
through an immediate further dilution of the acid in the surface 
layer of soil. While part of the apparent freedom of the aerial parts 
of the plants from direct acid injury may be due to the slight tendency 
of liquids to adhere to pine seedlings, drops of 1 to 256 acid solution 
by volume (0.71 per cent by weight) frequently remained caught in 
the center of the whorls of cotyledons of yellow-pine seedlings. 
This localization of solution was not accompanied by any noticeable 
localized injury. The experience of Craig,’ indicating direct injury 
to the foliage of grapes, plums, and apples out of doors by a solution 
containing but 0.25 per cent of the acid, was more closely duplicated 
in the case of seedlings of a grass resembling a common native species 
of Panicum, which occurred in some of the plats. Definite character- 
istic spots of dead leaf tissue were noted on the grass plants in a few 
cases in plats treated with a solution of 1 to 512 by volume (0.36 per 
cent). The solution adhering to the leaves is, of course, concen- 
trated by evaporation of the water after application, so the injury 
from spraying with solutions is actually caused by a much stronger 
solution than that applied. 

The tests outlined in the foregoing statement indicate that after 
the seed begins to germinate, any application of sulphuric acid suffi- 
cient to affect materially the activity of the damping-off parasites 
will cause the death of the radicles of some of the pine seedlings. 

In applications after the beginning of germination, the concentra- 
tion of the solution applied, as well as the amount of acid used per 
square foot, seemed distinctly related to the amount of injury to the 
roots of the seedlings. This indicates that the injury occurred very — 
promptly after the application of the solution, before diffusion — 
between the upper and lower layers of soil had time to equalize 
quantities and concentration of the soil solution. The younger parts 


of the roots were still in the upper 1 or 2 inches of soil in most cases 


at the time the injurious solutions were applied. 


INJURY TO PINES BY SULPHURIC ACID APPLIED AT THE TIME OF SOWING. 


In applications made at the time of sowing it was found that 
stronger treatments could be given without injury to the pines than 
when the treatments were delayed until germination. Stronger 
treatments were also required in order to control parasitic fungi, so 
that it was necessary in these tests also to work with treatments 
strong enough to cause injury to seedlings. Because of the numerous 
advantages of acid treatment at sowing, from the standpoint of 
disease prevention and nursery practice, a detailed study of the 
injury it causes to seedlings was undertaken with a view to pre- 
vention. 


1Craig, John. Effects of dilute sulphuric acid on foliage. In Canada Exp. Farms, Rpt., 1893, p. 101- 
102, 1894. 


INJURY BY DISINFECTANTS TO SEEDS AND ROOTS. rie 


_ The procedure followed in treatment at sowing time was to (1) 
prepare the seed bed, (2) soak it with the disinfectant, (3) sow the 
_ seed broadcast, (4) cover with one-fourth inch of dry soil, and (5) 

apply the rest of the solution. The seed bed was not stirred up after 
the application of the solution was commenced. In no case in 
spring-sown beds has there been any indication that the treatments 
injured the pine seed before germination started, although the treat- 
' ment, in strengths varying from 0.125 to 0.375 fluid ounce of acid 

per square foot, has been tested during the past three seasons in 19 
_ different experimental series of jack pine, in 4 series each of yellow 
pine and Norway pine, and 1 series of Corsican pine. The proportion 
of germination in acid plats was nearly always higher than in the 
untreated plats (due to the prevention of parasites rather than to 
_ stimulation), and as high as in plats of soil disinfected by heat. 
_ In jack-pine plats in which germination was reasonably prompt 

(12 to 14 days) and no special measures were taken to prevent injury 
_ to seedlings, many seedlings were killed or injured after germination 
_ began on plats which had received, respectively, 0.125 ounce and 
- 0.141 ounce of acid per square foot at sowing, while 0.188 ounce per 
square foot always resulted in injury unless special protective 
_ measures were taken. 


DESCRIPTION OF THE INJURY. 


Injury to the seedlings in plats treated at or before the time of 
- sowing took the form of damage to the growing apices of the radicles, 
_ with the result that extension of the root was stopped. 
_ Whether the meristematic apical cells were actually 
_ killed or simply lost their meristem qualities was not 
_ determined, though the former is the more probable. 
_ In most cases, root apices rendered incapable of growth 
retained their normal cream color for a few days after 
_ the injury and often recovered, though in severe cases 

they turned dark very soon. Plate I and text figures 
1 and 2 show chemically injured seedlings. Plate I, 
figure 1, shows a healthy seedling, younger than the 
~ injured seedlings in figures 2, 3, and 4 of this plate, so 

that the darker color of the upper parts of the roots of 
- injured seedlings is chiefly due to difference in age, 
rather than to the effects of the acid. The dispropor- te. 1.—Pinus ai- 
_ tionately short roots of the injured seedlings are espe- rea 
cially noteworthy. growth has just 
_ Ordinarily the growth of cells just back of the apex — penrsumecby 
_ was not entirely prevented, so that the root tips be- 11 days suspen- 
came truncated as a result of the uneven growth. %™ *™ 
(PL. I, fig. 2.) Distorted growth was also common. The capacity 
for absorption was usually retained by the injured roots for some | 


8 BULLETIN 169, U. S. DEPARTMENT OF AGRICULTURE. 


time. Although injury to root apices commonly took place before a | 
the seedlings appeared above the soil, most injured seedlings came 
up, and when the soil around the short root was kept moist the 
erowth of the stem and leaves continued for some time at a normal — 
rate. All of the development of the aerial parts of the seedlings 


shown in Plate I, figures 2, 3, and 4, was made after the extension of q 


the root had Been Saaee Be adel 5 

Injured seedlings ordinarily lived till the surface of the upper a 
part of the root became brown and presumably impervious, as in | 
the older parts of the root in healthy seedlings ¥ 
after two or three weeks. In the worst in- © 
jured seedlings this root browning seemed to — 
take place somewhat earlier than in healthy 
plants. The decrease in diameter which is no- 
ticed in the older parts of normal roots at the 
time of browning was seldom observed in acid- — 
injured roots. Because the injured seedlings 
were not able to develop new root tissue, ab- 
sorption ultimately became impossible and — 
death from drought ensued. The seedlings ~ 
shown in Plate I, figures 2 and 3, have prac- — 
tically reached this condition, though both 
still appeared to be growing normally when 
they were dug up. Plate I, figure 4, shows a 
seedling injured at the same time as that in 


Plate I, figure 3, which has recovered by recom- — 


mencing root seen 
Where the roots of injured seedlings were | 


S) 


because the soil was allowed to dry out to be- — 
Z low the level reached by the short root or be- — 
Fie. 2.—Pinus ponderosa in- cause the short root did not afford sufficient — 
oe Ponty has been re. mechanical support for the top-heavy stem, — 
sumed by a number of later- and the seedling fell over or was washed out 
als. (Natural size.) ; , a 
in watering. In the cases where injury was 
earliest, so that the radicle had scarcely emerged from the seed coat — 
by the time its tip was killed, the seedlings failed to appear above ~ 
ground at all. 
In a good many cases seedlings which had extended their roots a — 
centimeter or more before injury ultimately recovered, either be- — 
cause of a resumption of terminal root growth, as shown in Plate I, — 
figure 4, or by laterals starting just back of the apex, as in text figure 
1. . In such cases the parts of the seedlings above ground at no time 
showed any effect of the acid, and the only way in which the existence — 
of injury could be detected was by examining the roots. Renewal — 


very short, the plants died very soon, either ~ 


Bul. 169, U. S. Dept. of Agriculture. PLATE I. 


AMS. He arHey 


HEALTHY AND ACID-INJURED PINE SEEDLINGS. 


Fig. 1.—Pinus divaricata, healthy seedling. (X2.) Fie. 2.—P. divaricata, acid 
injured. (X2.) Probably not capable of recovery. The root growth was 
stopped before the seedling came up. The entire development of the stem 
and leaves above ground has taken place since the cessation of root growth. 
Fig. 3.—P. laricio, acid injured. (xX 2.) Injured when so little root had 
developed that there was no possibility of a resumption of growth. TIllustra- 
tion made 10 days after the killing concentration occurred. Fic. 4.—P. 
laricio, acid injured. (X1.) Recovering by terminal resumption of root 
growth, as shown by the white root tip. 


INJURY BY DISINFECTANTS TO SEEDS AND ROOTS. 9 


of root growth in injured seedlings was most commonly observed 
from 8 to 12 days after the original cessation of growth. Dr. Perley 
_ Spaulding has advised the writer that a year prior to the observations 
here reported he found this resumption of growth by laterals in 
injured western yellow-pine seedlings in experimental plats at 
_ Burlington, Vt. 
It is seldom possible to recognize acid injury immediately after 
- occurrence. Even after death takes place it is not possible to dis- 
 tinguish the deeper rooted injured seedlings from those killed by 
_ parasites, as by the time the seedling gives indications of death 
_ above ground the roots are too badly decayed to show what caused 
death. The best way to detect acid injury is to dig up healthy- 
looking seedlings in different parts of a plat a week or ten days after 
the first seedlings come up. The roots of the seedlings will be found - 
_ to have the following characters: | 
(1) Acid-injured seedlings (PI. I, figs: 2 and 3). Length, one-fourth to five-eighths 
ofaninch. Oolor, if brown at all, tip will be as brown as the rest; root firm throughout. 
(2) Healthy seedlings (PI. I, fig. 1). Length, 1to3inches. Color, upper part may 
' be brown, but tip will be white. 
(3) Damped-off seedlings (attacked by parasites). Length, usually same as healthy, 
but lower part may be entirely decayed, making root appear short. Some part of root 
examined will always be found soft from decay, while acid-injured roots are firm 
throughout. 
_  Norr.—Care is needed to distinguish between the short root of an injured seedling 
_ and a healthy root which has been broken off short by accident. With a little prac- 
_ tice, the difference between a root tip and a broken end can be easily recognized. 


PREVENTION OF INJURY BY LEACHING. 


_ The first attempt to prevent injury to germinating seedlings from 
__ the residue of acid applied at sowing was by leaching. To different 
_ plats in a bed which had received 0.188 ounces of acid at sowing 
_ ‘three days earlier, 4, 8, 12, and 16 pints of water per square foot, 

_ respectively, were applied. The plats were thereafter given sprin- 
klings equal to 0.3 of an inch of rain often enough to insure germina- 
tion, which took place 11 days after sowing. The heaviest initial 
watering, equivalent to 3.2 inches of retained rainfall, prevented 
_ most of the injury which occurred on the other plats, but not all. The 

_ plat receiving but 4 pints (0.8 inch) suffered heavily, while the 
amount of injury in the 8 and 12 pint plats was intermediate. Ina 
second test, with an acid treatment of 0.211 ounce at sowing, fol- 
lowed by germination in eight days, a 6-inch watering was given 
_ three days after sowing. The bed was purposely allowed to become 
_ quite dry on the day of germination, and later examination showed 
_ that a small number of the pines were injured. In a third test, this 

_ 6-inch watering was used on a bed which had received 0.313 ounce 


De of acid. The bed was allowed to become somewhat dry 10 days 
* 71222°—Bull. 169-152 


10 BULLETIN 169, U. S. DEPARTMENT OF AGRICULTURE. 


after the acid treatment (t day before germination), and a number 
of seedlings were injured. It was evident from the results obtained 
that these heavy applications of water leached out enough acid mate- 
rially to reduce acid injury. Leaching is evidently not practicable 
as a method of preventing injury at most nurseries when germination 
is prompt. In a sandy soil when the weather is cold and germination 
requires 18 or 20 days, leaching soon after the application of acid 
may be a practicable method of preventing injury. 


PREVENTION OF INJURY BY FREQUENT WATERING. 


Fortunately two definite relationships which opened the way for 
developing a practicable method of controlling the injury to the 
pines were found. It was found that the amount of water in the soil 
at the time of germination bore a direct relation to the amount of 
injury, and that injury seldom occurred after the seedlings had sent 
their roots down five-eighths of an inch into the soil. The length of 
root shown in Plate I, figure 3, is typical of injured seedlings in 
general. The stoppage of growth of root apices in treated beds — 
always occurred at times when the upper soil became relatively dry 
and while the root tips of germinating seedlings were still in the upper 
five-eighths inch of soil. Although the nurserymen water the beds 
often enough to prevent drought injury to the seedlings, great varia- 
tion in the moisture content of the surface soil occurs. The upper 
one-fourth inch of soil at this nursery just after watering has fre- 
quently been found to contain 21 to 25 per cent of moisture, while at 
the same points the soil when dry has contained but 1.96 per cent of 
water, the average of 12 determinations made on different occasions. 
In a single period of 11 hours the moisture content of the surface soil 
at four different points in the seed beds dropped from 12.02 to 1.85 per 
cent. This of necessity caused great variations in the concentration. 
of the soil solution. While beds were not ordinarily allowed to 
become as dry as this during the germinating period, they often 
became quite dry at the surface. A little below the surface the mois- 
ture content of the soilis more stable. The most rapid loss of moisture 
found in the seed beds from 1 to 2 inches in depth during the period in 
which determinations were made was a drop from 17 to 114 per cent 
in a period of approximately 36 hours. This explains the relative — 
safety of roots which have penetrated below the upper half inch of 
soil. That the root above the tip should resist relatively high con- 
centrations of acid is in agreement with the results of Heald* and 
other investigators, who find the tip of the root to be the portion most 
sensitive to poisons. The difference in resistance between the very 

1 Heald, F. D. On the toxic effect of dilute solutions of acids and salts upon plants, In Bot, Gaz., 
Vv. 22, no. 2, p. 130, 1896, 


‘ 


INJURY BY DISINFECTANTS TO SEEDS AND ROOTS. 11 


tip of the root and the tissue just back of it is well shown by the 
location of the new laterals developed by the seedling in figure 1. 

In addition to the increased concentration of the acid solution 
_ already in the surface soil, due to the decrease of the solvent, acid 
from lower levels is presumably brought up to the surface by the 
capillary rise of the soil solution to replace that lost by evaporation. 
When the treated soil is soaked thoroughly with water and subjected 
to continuous evaporation for several days, but at a rate slow enough 
to avoid drying the surface soil entirely and breaking the capillary 
connection, this continuous upward movement of solution ultimately 
results in killing concentrations in the surface soil, even while it is 
still very moist. The problem of preventing injury to seedlings 
therefore becomes one of not only keeping the surface soil moist, 
but of maintaining a fairly constant downward movement of soil 
moisture, or at least of preventing a continuous upward movement 
- for any considerable period, until after the roots of all seedlings 
have extended half an inch into the soil. Experience has shown 
that’ this can be done more easily with frequent lght WAPenBgS 
- than with heavier and less frequent applications. 

A very few hours’ delay in watering at a critical time has in some 
cases been enough to cause the killing of root tips by acid. Under 
certain conditions, as outlined in the foregoing paragraph, injury 
occurred before the beds appeared at all dry at the surface. Since 
appearances could not be relied on to show when watering was 
needed, systematic watering was tested. Furthermore, variation in 
individual judgment made necessary the use of measured quantities 
of water. Daily waterings equivalent to 0.4 of an inch of rain 
were not in all cases sufficient to prevent injury entirely. However, 
half this quantity applied twice as often, with the soil wet to begin 
with, was found sufficient to prevent all injury from moderate 
amounts of acid, even in very hot, dry weather. For large beds at 
this nursery which have received 0.188 ounce of acid at sowing, 
watering equivalent to 0.3 of an inch twice daily during the germina- 
tion period has been recommended for summer use, so as to make 
certain that in the necessarily uneven large-scale work all parts of 
the bed will get at least 0.2 of an inch at each watering. 

For work in cold spring weather, when the germination period 
is long, the expense of this special watering becomes considerable, 
and it further cools the soil to such a point that germination may be 
_ still more delayed. No such frequent watering is necessary to 
_ prevent injury in cool weather, but because of occasional hot, dry 
_ weather in early spring it is not safe entirely to abandon watering 
twice daily. A rather extreme instance of the variable temperature 
at Halsey was the rise of the temperature, as shown by a Weather 


12 BULLETIN 169, U. S. DEPARTMENT OF AGRICULTURE. 


Bureau thermometer under a shelter 4 feet from the ground, 
from 37° F. at 8 a. m. to 98° F. at noon of the same day in April. 
The evaporation from white porous-cup atmometers set in the seed 
beds has varied from 14 to 59 c. c. for 24-hour periods 10 days apart, 
and still greater variations are to be expected from the darker 
soil surface. Hot, dry days increase the danger from acid injury 
both by increasing water loss and consequent acid concentration 
and by hurrying germination before the acid solution in the upper 
soil has had much time to decrease in strength. In view of the 
variability of weather conditions, the system now followed in prevent- 
ing acid injury is to water daily in ordinary spring weather, every 
other day or even less often in misty or rainy weather, and twice 
daily when the temperature exceeds 80° F. In clear weather, 
waterings are to approximate 0.3 of an inch, while in cold and cloudy 
weather 0.2 of an inch is to be used. This watering system has proved 
practicable, and has been entirely successful in preventing injury 
to pines from acid applied at the time of sowing. 


RELATION OF STRENGTH OF TREATMENT TO EXTENT OF INJURY. 


The degree of dilution of the sulphuric acid in applications at 
sowing had no apparent relation to the amount of injury likely to 
result to the seedlings; that is, if 0.25 ounce of acid per square foot 
was applied, it made no difference, so far as noticed, whether it was 
dissolved in 64 or 192 volumes of water. There was not a sufficient 
number of tests with this factor as an independent variable to estab- 
lish an entire lack of relation, but it is quite certain that within the 


limits given the amount of water used in making up the solution is 


not an important variable. 

The first results indicated a rather surprising lack of constant rela- 
tion between the amount of acid used per unit of soil surface and 
the amount of injury. In an early test of varying amounts of acid, 
all of which caused considerable losses of seedlings, the final stands 
in the plats were as follows: 


Series 501.—Jack-pine plats; all except the check plats were treated with acid at 
sowing. 

Eight check plats untreated. Final stands ranged from 71 to 163 per square foot; 
average, 122. 

One plat, 0.125 fluid ounce of acid per square foot at sowing. Final stand, 216. 

One plat, 0.141 ounce of acid. Final stand, 118. 

Two plats, 0.188 ounce of acid. Final stands, 191 and 143; average, 167. 

Three plats, 0.234 ounce of acid. Final stands, 107, 110, and 80; average, 99. 

Two plats, 0.250 ounce of acid. Final stands, 23 and 153; average, 88. 

One plat, 0.313 ounce of acid. Final stand, 94. 

Two plats, 0.375 ounce of acid. Final stands, 11 and 116; average, 64. 


In this series, as in those reported in the remainder of this paper, 
the plats received weights of seed proportional to their area, 


. 


INJURY BY DISINFECTANTS TO SEEDS AND ROOTS. 13 


_In this series the variation between individual plats is great. 
Especially in the cases of the 0.250-ounce and the 0.375-ounce plats 
the variation between plats given the same acid treatments is much 
_ greater than the average variation between plats given different 
treatments or between the untreated plats, which are subject to 
- much heavier variation from the action of parasites than the acid- 
treated plats. However, the averages indicate a distinct increase in 
_ the amount of injury as the quantity of acid is increased. The great 
individual variation between plats with the same acid treatment is 
to be explained by two factors which were not controlled. In the 
first place, different plats germinated at somewhat different times. 
Some plats therefore had a much greater average root length than 
others at the time the killing concentrations of the soil solution 
_ occurred. This greater root length resulted in the sensitive tip being 
farther down in the soil, where the acid solution does not become as 
concentrated as in the soil at the surface. It may also have been 
true here, as found by McCool? in his work with barium, strontium, 
_ sodium, and ammonium, that the root tips of seedlings a few days 
_ old are less susceptible to injury than those of seedlings which have 

just germinated, so that the age of the seedlings may have been even 
more important than the location of the root tips in making the older 
seedlings more resistant. Furthermore, those with the longer roots 
_ were not only less likely to be injured but also had a better chance 
' to recover. (Compare Pl. I, figs. 3 and 4.) A more important 
_ variable factor in causing different results in plats with identical acid 
_ treatments was the watering during the germinating period. While 
all plats were watered at the same time, no attempt was made in. 
_ series 501 to secure special uniformity in watering, and some became 
drier than others. A later test of different amounts of acid was made 
_ with plats sprinkled with measured quantities of water twice daily 
_ during the germination period. Germination took place nine days 
after the plats were treated and sown. The results are given in 


- Table II. 


_ Tasre III.—Relation of the amount of acid applied and the thoroughness of subsequent 
_ waterings to the death of pine seedlings on plats treated with sulphuric acid at the time 
of sowing. 
[Seedlings per square foot surviving 44 days after germination. ] 


Treatment (ounces of acid per 
Square foot). 
Water per square foot. 


0.211 0.250 0.313 


Sea pints at each watering................2........-.- 5 ae taal seedlings..|........-. 179 142 
1.5 pints at each watering......................- LR ee oe dog:s: 281 151 91 


) Semeebec each Watering... 22... anne eee eee eee cee e eee OO: i: 125 64 47 


q -1McCool,M.M. The action of certain nutrient and nonnutrient bases on plant growth. N. Y. Cornell 
_ Agr. Exp. Sta. Mem. 2, p. 159-162, 1913. 


, 


14 BULLETIN 169, U. S. DEPARTMENT OF AGRICULTURE. 


The decrease in stand both with decreasing amounts of watermg 


and with increasing amounts of acid was sufficiently consistent in 
this experiment to establish beyond a reasonable doubt the relation- 
ship, both of the amount of acid used and of the amount of watering 
done, to the acid injury. In the weakest acid plat with the inter- 
mediate watering, no appreciable injury occurred. Because of the 
variation in germination aside from the influence of acid, the results 
were not always quite as consistent as in this series, but no reason has 
been found to doubt the relation between the amount of acid and 
the extent of injury in beds treated at sowing. 


INJURY TO PINES BY SULPHURIC ACID APPLIED BEFORE SOWING. 


In treating beds with sulphuric acid to kill fungous parasites the 
attempt was made to evade toxic action on the seedlings by applying 
the acid a number of days before sowing. Jack pine was also used 
in most of these tests. In such cases the beds were ordinarily hoed 


and raked just before they were sown, so that the upper 2 or 3 inches © 


of soil was well mixed after the acid was applied. In the plats treated 
at sowing there was the possibility that the injury was limited to the 
surface five-eighths of an inch of soil, simply because this layer of 
soil had acted as a trap for the acid, absorbing most of it at the time 
of application. In the case of plats treated before sowing there was 
no such possibility. The seeds were in most cases covered with about 
one-fourth of an inch of soil taken from the upper 1 to 14 inches of 
the soil of a near-by area that had been given the same treatment as 
the plat sown. Considerable injury occurred in plats which received 
0.25 and 0.375 ounce of acid nine days before sowing (20 days in all 
elapsing before germination), although the treated plats recerved 
approximately 1.6 inches of water five days after sowing, followed by 
0.3 to 0.4 of an inch daily till after germination. The slight drying 
of the surface soil which resulted in the injury on these plats took 
place the first day after germination, 21 days after the application of 
the acid. 

In another series, using the same species of pine, amounts of 
0.281, 0.375, and 0.687 ounce of acid per square foot were applied 11 
days before sowing, two plats receiving the latter amount. Four 
days after sowing, the plats were given approximately 1.6 inches of 
water, followed by waterings of approximately 0.3 to 0.4 inch on 
the sixth, eighth, ninth, tenth, and eleventh days from sowing. 
Germination took place on the eleventh day, 22 days after the 
application of the acid, and on the morning of this day the soil 
surface became somewhat dry, but not dry enough to cause appre- 
ciable drought injury in the nonacid plats. As shown by later 
_ examination of the length of the acid-injured roots, injury took 


ee ee ee 


INJURY BY DISINFECTANTS TO SEEDS AND ROOTS. 15 


place at this time. It was most serious in the 0.375-ounce plat, 
mainly because it had become somewhat drier than the rest. Even 
the 0.281-ounce plat seemed more injured than the 0.687-ounce 
plats, which were not seriously affected. The activity of parasites, 
mostly, probably, Pythiwm debaryanum, in the soil in these plats 
during and after the time that this injury was occurring to the 
seedlings is a matter of some interest. The slight relationship 
between the amount of acid used and the amount of injury taking 
place in these plats 22 days after treatment emphasizes what has 
already been said as to the apparent equalization of strength of 
acid solutions of different original strengths in the soil as the con- 
centration decreases. 

Plats of jack pine which had been entirely killed by applications 
of 0.172 ounce of acid at the date of germination and 0.086 ounce 
_ six days later, 0.258 ounce in all, were resown with the same species 
23 to 24 days after the first treatment, germination taking place 
34 to 36 days after the first treatment. No serious injury occurred 
to the seedlings in this second sowing, though no special wataring 
was given. Similar results were obtained with yellow pine in plats 
treated with 0.3 ounce of acid 39 days before sowing (50 days before 
germination), no serious injury occurring despite the entire lack of 
any special watering. In all cases, acid applied before sowing can 
be kept from causing injury quita easily by the watermg methods 
used for beds treated at sowing. The tests indicate that if germina- 
tion takes place at any time during the first month after 0.25 ounce 
of acid is applied to the beds it will be necessary to give more than 
the usual nursery watering during the germination period in order 
to insure freedom from injury to the seedlings. Though it is some- 
what easier to prevent acid injury in beds treated several days 
before sowing, treatment at the time of sowing is so much more 
effective against the damping-off parasites that it is considered 
preferable. 


RELATIVE RESISTANCE OF VARIOUS SPECIES OF PINE TO SULPHURIC ACID. 


There was considerable difference in the amount of injury caused 
by similar acid treatments on different species of pine. Jack pine, 
as a rule, seemed most liable to serious injury, while yellow pine was 
_ least often damaged, and Norway and Corsican pines were intermedi- 
ate. The resistance of yellow pine as compared with jack pine was 
_ especially evident in beds treated shortly after germination. Most 
_ of this apparent difference in resistance is due not to variations in 
_ the capacity of the root tips to endure acid, but to a difference in 
_ the rate of growth. Yellow pine has a seed approximately ten 
_ times as heavy as that of jack pine and sends its root down much 


16 BULLETIN 169, U. S. DEPARTMENT OF AGRICULTURE. 


faster at the start. By the time a yellow-pine seedling breaks 


through the soil cover its root has gone down much farther into the 
soil than with jack pine at the same age, and the application of a 
disinfectant to the soil surface at this time is therefore much less 
likely to injure the yellow-pine root tip. When disinfectants are 
put on the soil at sowing, the root tips have not yet emerged from 
the seed, and yellow pine has no such distinct advantage over jack 
pine. There is still a difference in depth of planting, however, /as 
yellow-pine seeds are usually covered deeper than those of jack pine 
and the root tips thus start at a lower level. The more rapid growth 
is also of some advantage in beds treated before germination, as 
injury occurs only at times of surface concentration. The root tips 


of yellow pine may get down far enough to avoid injury from a con-" 


centration which occurs before the tips of jack-pine roots have 
reached the safety zone. While yellow pine has been less often 


injured than jack pine by acid applied at the time of sowing, concen- * — 
trations occurring while there was a large porportion of yellow-pine 


root tips in the surface soil have killed large numbers of seedlings. 
In one extreme case, in which 0.250 ounce of acid per square foot 
was applied 28 days before sowing and repeated at sowing, with 
germination following five to. six days later; only two-thirds as many 
seedlings came up as in untreated plats, and of these over 90 per cent 


died, nearly all as a result of acid injury. On the whole, while ~ 


yellow pine has been much less often injured by acid treatment, the 
evidence indicates little, if any, greater resistance of its root tips 
than that shown by jack pine. 

Corsican pine shows injury in the same way as jack pine (PI. I, 
figs. 2 and 3). It has a seed smaller than yellow pine, but still much 
larger than jack pine and producing a faster initial root growth. It 
therefore seems a little less liable to injury than jack pine, for the 
same reasons that yellow pine is less liable. Norway pine on the 
other hand, though having a larger seed than jack pine, makes a 
much slower initial root growth at this nursery. Its slightly longer 


germination period gives the acid more time for dissipation, but the 


indications are that the root tips of this species possess a slightly 
greater acid endurance than those of jack pine. Corsican and Nor- 
way pine have not been tested as much as the other two species, and 
the evidence obtained as to their relative resistance has less value. 


INJURY TO MISCELLANEOUS PLANTS BY SULPHURIC ACID. 


The watering given pine seed beds at the Halsey nursery resulted 
in the germination of great numbers of previously dormant weed 


seeds of the species listed on pages 3 and 4. These ordinarily began to — 


appear a little later than the pines and continued to come up in con- 


INJURY BY DISINFECTANTS TO SEEDS AND ROOTS. 17 


siderable quantities for the first two or three weeks, after which time 
the number which came up decreased. 

Most of the data on the effects of sulphuric-acid treatments on 
_ weeds were obtained on beds treated at the time of sowing. The 
observations indicated marked differences between the species 
observed in their ability to grow in soil recently treated with acid. 
It was evident throughout that the pines were less easily injured than 
most of the weed species. On plats which received no special water- 
ing till after germination, 0.125 ounce and 0.141 ounce of sulphuric 
acid per square foot, respectively, at the time of seeding entirely 
prevented weed growth. The untreated plats in this series were 
fairly well covered with Portulaca and grass species and with a few 


plants of Amaranthus. At sowing in another series on a plat given 


very frequent watering, 0.125 ounce of acid failed to reduce per- 
ceptibly the number of common weeds. Another plat given the same 
treatment, which had also received 0.125 ounce of acid 13 days before 
sowing, showed entire freedom from weeds, with only partial injury 
to the pines. In repeated tests during successive seasons, treatments 
of 0.188 ounce of acid at the time of sowing regularly prevented 
practically all weed growth for the first three weeks after the germi- 
nation of the pines. In some cases no weeds came up in treated beds 
until a month after the appearance of the pines. Beds treated with 
acid and so watered as entirely to prevent injury to the pines were 
nevertheless so free from weeds as a result of acid application that 
the cost of weeding the treated beds during the whole season has 
been only one-third that of untreated beds. 

The appearance of Equisetum in acid-treated plats was of some 
interest. In an insufficiently watered acid plat on which the pines 
were seriously injured and on which not a single phanerogamic weed 
appeared, more Equisetum developed than in most of the untreated 
beds in the nursery. Equisetum was not a common weed anywhere, 
but it occurred more frequently in the acid beds than in the beds not 
treated. 

The grasses throughout gave evidence of greater ability to endure 
the acid applied to the soil than did the dicotyledons. They were 
usually the predominant weeds and often the only ones in acid plats. 
This greater predominance of grasses over dicotyledons in the acid 
plats left little doubt as to their superior endurance of this treatment. 
Unfortunately, few data were secured as to the factors which-con- 
trolled the varying capacity of the different plants observed to 
~ endure acid ‘applied to the soil. Most of the injury to the weeds did 
not occur in just the same way as to the pines. In the pines the 
commonest phenomenon was root injury, which allowed the seedlings 

71222°—Bull. 169—15—3 


18 BULLETIN 169, U. S. DEPARTMENT OF AGRICULTURE. 


to come up, but caused them to die a few days later. With the 


weeds, nearly all that came up were quite certain to survive. The 
extent of the injury to weeds was shown chiefly by the small number 
of weeds which appeared on the acid plats as compared with the 
checks. The failure of seriously injured weed seedlings to appear 
above ground, as did most of the injured pines, may be due in part to 
a larger amount of stored food material in the pine seed and in part 


to a greater depth of soil over many of the weed seeds. « It is barely — 3 


possible that many still dormant weed seeds were lulled at the time 
of the applicatioa of the acid. Some of the weed seeds in late-sown 
plats commence germination at or before the time of acid application, 
and are therefore probably killed at the time of application. The 
frequent occurrence of healthy Equisetum in beds where the acid 


killed the pines may be due entirely to the presence of old rootstocks — j 


and not to superior tolerance of acid. It has been suggested that 
the survival of grass where acid prevented the appearance of dicoty- 
ledons may be due to the branching habit of the grass roots, which 
makes injury to the tip of the primary radicle of less importance 
than with the plants which depend largely on a main taproot. 7 
Despite the qualifications in the preceding paragraph it seems 


quite certain that a great many germinating weed seeds which were | 


dormant at the time of the application of the acid and were deeper 


in the soil, and therefore exposed to lower concentrations of acid — 


than the pines, were killed in much the same way as the pines by 
amounts of acid which would not injure the pines. The experiments 
indicate not only a distinctly greater tolerance for sulphuric acid in 
the pines than in the angiosperms most commonly represented in the 


beds, but within the angiosperms a somewhat smaller difference in 


tolerance between the grasses and dicotyledonous species was ob- 
served. ‘Tests in water culture would be necessary to establish the 
differences in resistance of the various species observed in these 
experiments and to give the differences a quantitative value. 

Treatments several days or weeks before sowing also had consider- 
able effect on the number of weeds found in the seed beds during the 
first few weeks after the germination of the pines. The use of 0.3 
ounce of acid 14 days before sowing, with sufficiently frequent 
watering after sowing to prevent injury to yellow pine, prevented 
the appearance of any dicotyledons for at least 43 days after treat- 
ment and allowed only a few grass seedlings near the edge of the 
plat and a couple of Equisetum plants. Mollugo, grass, and Portulaca 
seedlings were common in all the check plats in this series, and Ama- 
ranthus and Euphorbia were present, while Equisetum was at least 
no more common in the checks than in the acid plats. | 


ee Oe ee ee ee 


INJURY BY DISINFECTANTS TO SEEDS AND ROOTS. 19 


: In another series, in which watering was frequent enough to pre- 
vent injury to most pine seedlings, 0.25 ounce of acid nine days before 
sowing kept the plat free from all weeds except three grass plants for 
14 months, and 0.375 ounce applied at the same time prevented 
weed growth of any sort. While grasses predominated in the un- 
treated plats, they also contained many plants of Mollugo, Portulaca, 
_ Amaranthus, and Euphorbia, their frequency being in the order 
| named, . 

In another series watered in the same way, 0.281 ounce of acid 
11 days before sowing and heavier treatments applied to three other 
plats at the same time entirely prevented weed growth till 47 days 
afterwards, while the checks contained the same species as those 
in the former series. 

In series 519, plats A, C, and D (Table VI), 0.25 ounce of acid 
had a distinct effect on the weed flora, practically the same as 

0.375 ounce, in plats examined 66 days after application. 

In another series, watered quite frequently after sowing in order to 
_ prevent acid injury, acid applied 14 days before sowing the pines 
was tested. On adjacent plats the upper 6 inches of soil was par- 
tially sterilized at about the same time by heating in a moist condi- 
tion to above 80° C. in an oven, all parts of the soil being brought 
to at least that temperature and kept there for not less than 10 
- minutes. The results are presented in Table IV. 


. 


TABLE I1V.— Weeds which appeared in plats disinfected by heat and by acid. 


Treatment (ounces 


Plat. of acid pe square Weeds found 42 days after treatment. 
oot 
muummur checks.......| None,......-:--.-.. 60 to 100 per plat; grass commonest, Mollugo and Portulaca fre- 
quent, Amaranthus occasional. 
hes 0 cl <a hoi Eeated sos 7.22 S552 Grass much as in checks, and making more vigorous growth; 
2 or 3 Portulaca plants, and 1 Amaranthus in each plat. 

reek Satan at 0.25 | 5 grass seedlings, with several Mollugo near edge. 

[DAG DAE RE EER ae .375 | 5 grass, with 1 Portulaca and 1 Mollugo near edge. 

Ciao eae .375 | 4 grass. 

eS 25 3 grass. 


Evidently, unless the grass seed survived a temperature of 80° C. 
_ or more, it had been blown into plats J and K after treatment, and 
_ migratory ability may explain part of its predominance over the 
_ dicotyledons in acid-treated plats. The results in general, neverthe- 
less, indicate that it is somewhat more resistant to acid than the 
_ dicotyledons. : 


RELATION BETWEEN TIME OF APPLICATION AND AMOUNT OF INJURY. 


_ The foregoing experience with pines and other plants in beds 
_ treated with acid at the time of germination, at sowing time, and at 
various times before sowing, shows clearly, as would be expected, that 


20 BULLETIN 169, U. S. DEPARTMENT OF AGRICULTURE. 


the time of germination is when acid applied to the beds will do the 
most damage to pine seedlings. The longer the period before or after 
germination takes place that the acid is applied the less danger there 
is of acid injury. The free acid in the soil solution would normally 


be decreased by diffusion or leaching downward into the subsoil, by — 


adsorption or solid solution by the soil, and by chemical interaction 


with other constituents of the soil or anit solution. No attempt has — 


been made to determine the relative importance of these different 
processes in the removal of the acid from the solution. It has seemed 
rather surprising that even with applications of acid as small as 0.25 
ounce per square foot enough acid remains free in the surface soil 
three weeks after application to kill the tips of jack-pine roots and 
prevent the growth of most dicotyledonous weed species for 14 months. 
In soil containing large quantities of carbonates there could be no such 
_ length of persistence of free acid. 


The amount of injury occurring in plats treated at different lengths — 


of time before germination and the comparative lack of relationship 
between the amount of acid used and the extent of injury in cases 
where more than 15 days elapse between treatment and germination 
indicate that the rate of dissipation of the free acid in the soil solution 
decreases rapidly as the concentration decreases. Very small 
amounts of acid have proved extremely injurious to root tips in the 


so at the time of application. While they lose this extremely toxic — 


character in a very few days after application, the final reduction to 
a point where no injury occurs requires a relatively long time. The 
apparent relative stability of very low concentrations of acid in the 


soil solution is in agreement with the general course of removal of a — 


solute either by diffusion or chemical reaction. 


ADDITION OF NEUTRALIZING AGENTS AFTER THE APPLICATION OF THE ACID. 


In different experimental series, plats treated with sulphuric acid — 
before sowing were later treated with neutralizing agents to prevent ~ 


acid injury. This procedure greatly decreased the effectiveness of 
the acid treatment against the damping-off parasites on whose 


account the work was being conducted, and so it was not exhaustively — 
tested. In no case was lime applied to the extent of equivalent — 


weights of the acid used. é 

The indications are that injury to pines may be prevented by small 
amounts of lime put on the beds a few days after the application of 
the acid. The results of the treatments are given in Table V. 


INJURY BY DISINFECTANTS TO SEEDS AND ROOTS. 21 


TaBLeE V.—IJnjury to roots in plats treated with sulphuric acid 12 to 16 days before sowing 
| and later treated with lime. 


Days from |g £ | se 
= @D 
coerce Dag acid treat- |=>5 | 28 
qu : ment to— | & B's 
Be | S3 
F om, 4 : 
e i BIAS 3 So iA: & Weeds present 14 months after 
Plat. = | 0° — ; [og om q DE os 
2 Ss es ce ga jag oD = acid application. 
ad 91 eo.1/8d] 8 Ise oo. ° 
oS ee WO a) 3 ard ats ~n ) 
@ (S}/HaAo| os] A g5e| 82 Ee 
he} BlosQig a [sas| of | 
3 a=| rod -_ B is o=- ‘gf 
Fy a |< 4 o |F cal a 
Pinus ponder- 
 osa (Series 
504-E)....... 0.375 | 2] 0.250 14 25 |0. 240 36 | None. | Half as many as in check plats 
P. divaricata of same series. 
(series 507): aals 
PEICHeCks NONC! |. .2|/ NOG... |c2i..< -]...o0 nclew eto -|onijo as scl peeesss« Grass and Mollugo abundant; 
some Amaranthus, Portulaca, 
and Euphorbia in each plat. 
1 Bea .375 1] 3 250 : 20 oon 36 ek 
Ko22| cg00] 4] 1333/9 | de | 132) 30 |. do’||Very, few, mainly grass and 
ge 1500] 4| :200| 7| 22] .392 Bor Ado. es MORE ROs DUE Brey en 
m3. .750 | 4 333 Meh Sc eTL lh Sag Uk | chet ei a a he eR a 
Wis fs 150 | 2 500 7 22 | .481 36 1: G00. Z 
oO: - 750} 6 500 7 22 | .481 36 | Slight. ; 
Reet. Pt ee MED. |e cheek, > babe xian dl ae akru nt) ORIG. L 
Ope ae eee tn MeO Ey tere See, woe ee cccw cdc cs do...|({More weeds than in untreated 
epee acGOs Els. <\ MOR ers | ae ceils obreinnn ans prere, dase do...|{ plats, in vigorous condition. 
8 SC eR 0 eh A i do... 
P. resinosa 
ob 514) 
hecks .....-. a NNN fc 18, Asso ay's renin a = [iets «sce cline - a Soe Grass, Mollugo, Euphorbia, 
Portulaca, and Amaranthus. 
et -500 | 2 . 333 5 24 | .321 36 | None. | Less than in checks; grass, 
Mollugo, and Euphorbia. 
oer 8 or -500 | 4 . 250 5 24 | .365 27 |...do..| Less than in checks; grass, 
Euphorbia, and Amaranthus. 
EMO co) 6 GOO |e v2 ocyaltnce eo |owineelle oe -S=se) do. .| As for check. 


1 Based on equivalent weights, assuming for the commercial sulphuric acid a maximum specific gravity 
7 § of 1.84 and.a purity of 95 per cent. No allowance is made for impurities in the lime. 

It appears that at least in plats M and O the acid applied was not 
reduced to two-fifths of its original amount during the first six or 
seven days after application. The injury in plat M, with its acid 
excess of only 0.24 ounce, when compared with the lack of serious 
injury in other plats with a greater excess of acid (notably plat E, 
with an excess 2 times as great), is a further indication of the 
relative stability of weak acid solutions in the soil. 

In the case of series 514, acid injury occurred in a plat treated with 
_arelatively small amount of hydrochloric acid, and it is quite certain 
that only the lime prevented injury in plats J and K. 

_ Ammonia was also tested, following sulphuric acid. On jack pine, 
0.750 fluid ounce of acid applied 21 days before sowing was followed 
afew days later by 0.469 ounce of the strongest commercial grade of 
ammonia. No injury to pines occurred. Watering in this series 
was very frequent, so injury might have taken place with ordinary 
watering despite the lime used. In series 514, a red-pine plat 
_ treated with 0.562 ounce of acid 13 days before sowing, followed by 


22 BULLETIN 169, U. 8. DEPARTMENT OF AGRICULTURE. 


0.5 ounce of ammonia eight days before sowing, suffered no injury. 
In this case the heavy acid treatment would probably have resulted 
in injury had not the ammonia been applied. 

From the practical standpoint, the prevention of injury from acid in 
pine seed beds by the use of neutralizing agents at this nursery is not a 
success, because beds so treated are often as badly infested by para- 
sites as beds which have received no disinfectant treatment. The 
action of heavy applications of lime on the beds is also somewhat in 
question. Amounts up to 0.5 ounce per square foot, as used in the 
neutralizing work, have, however, been used alone without any bad 
effect. In one case 0.73 ounce per square foot (equivalent to 1 ton per 
acre) used on jack-pine beds at or before seeding in two different 
series was followed by a serious decrease of germination, and in the 
other case by a marked increase in the number dying after the seed- 
lings came up. Whether the effect was a direct injury to the seed- 
lings or a stimulation of the parasites which attack them was not 
determined. 

The effect on weeds of acid followed by lime is also shown in Table 
V. Much injury to weeds occurred despite the neutralization several 
days later of two-fifths of the acid appled. However, it is quite 
certain, especially in the case of series 504, plat E, that much more 
injury would have occurred had not the lime been applied. Three- 
fourths as much acid applied to another plat in this series at about the 
same time, and not followed by lime, prevented the growth of angio- 
sperms on the plat. The extremely rapid growth of the weeds on the 
acid-lime plats a few weeks after the application of the lime indicates 
that most of the remaining acid had been broken down by the lime. 
If enough lime had been used to neutralize one-half or three-fifths 
of the acid applied, it is entirely probable that all of the acid remaining 
at the time of the lime application would have been broken down and 
the soil rendered entirely safe for sowing any crop plant desired. 
Because the lime applied was not sufficient to take up at once all the 
acid remaining in the soil at the time of application, as indicated by 
the injury to the pines in series 507, plats M and O, the question as to 
whether the acid prevented weed growth largely by killing dormant 


seed or entirely by killing germinating seed, as with the pines, remains 


undecided. 

Ammonia, 0.469 ounce per square foot, was used in 3 pints of water 
a few days after the application of 0.750 ounce of acid, with watering 
sufficient to prevent injury to jack pine even on unneutralized acid 


plats. Examination approximately 45 days after the ammonia appli- — 
cation showed an entire absence of weeds on the acid-ammonia plat, as 


on the acid plats, while the four checks all contained plants of grass, 
Mollugo, Amaranthus, and Portulaca. For 37 days after the ammonia 
was applied 0.562 ounce of acid followed by 0.5 ounce of ammonia five 


eee ON a 


— 


vl ea 


INJURY BY DISINFECTANTS TO SEEDS AND ROOTS. 23 


days later resulted in preventing most weed growth, but not all. 
Ammonia alone, 0.5 ounce per square foot, had no effect on the weed 
stand 65 days after application. 
TESTS OF MISCELLANEOUS DISINFECTANTS. 
Tests were also made with disinfectants other than sulphuric 
acid. These are summarized in Table VI, together with enough 
sulphuric-acid tests to afford a basis for comparison. Because a plat 


can be directly compared only with the others sown at the same time, 
the plats are grouped by series rather than by disinfectants. 


TaBLE VI.—Injury to pines and weeds by miscellaneous disinfectants. 


Days from 
Disinfectant. treatment 
to— 
Plat. Per square Injury to pines. Weeds ee ian 
foot. Weed cae eh 
oo ROWS gamit 
used. || ang. : 
Gunes: os nation. 
Germination _re- 
Pints. oe to ee 
an one-sixt 
Pinus divaricata:} es Galo) \ 0.017 || 1 4 of that in checks. 
CO sieis2. 52>. Ree ionin : 275 imac alee Ca Nearly all seed- 
Apis ; lings which 
came up were 
severely injured. 
OB bata Weiss py Sulphuric acid 172 | 1.4 ON ices t as Injury not serious. 
ame ey 5|'s <<<. Ge Sees 257 | 1.4 OUR ars cee GOs el cee 
P. ponderosa:! 
7 er Formalin.....| .25 2 O12. R22 Germination re- 
duced to less 
than one - quar- 
ter that on other 
plats. No death 
due to disinfect- 
ant after germi- 
oe nation. 
sl? 2 29 
MEE oul Bios ee ae || eee None. 
P. divaricata:! 
TE EES OS ls ee ee ae ee ee ee ae Portulaca and 
checks). grass abundant; 
Amaranthus  re- 
troflecuscommon. 
Dee ieee Hy drochloric .188 | 2 Ou|:30-31 2IeNone.-. 25/38. - One - half or two- 
acid. thirds as many as 
in checks. 

Oe os 203- Nitric acid. -.. <oO0 |e 3 0 | 30-31..) Slight or none..... Grass rare; Portu- 
laca, 2 or 3 plants. 

Beo..-.--| Sulphuricacid|; .125| 2 02}; 30-322.) Slight. .:... 52... None. 

1 ee es eee Gomes. 2c 6s 14k | ES 0 | 30-31..| Moderate to heavy. Do. 

16 (ee te ol ee ae 188 | 2 0 | 30-31..| Moderate......... A single trifoliate 

: legume. 
1 es eee Gomer E aAliyt eed 2 0 | 30-31..) Very heavy....... None. 
P. ponderosa: 4 

LS) ae is i ene et be ee | ee ee Mollugo, grass, and 
checks). : Portulacaabund- 
ant; Amaran- 
thus and Euphor- 

bia frequent. 
eee |) Mormalins...| .562,| '3 143) -43h 254 1\((0) eee ee ee Half as many as in 
checks, mainly 

grass. 

Ue tie Sa Sulphuric acid 281} 2 145 | 43) eee Gojsreeisee se Oy Grass,'at edge only; 
Equisetum, 2 
plants. 

ee emer BOSC GHIA MY SESS Pg OP 20s 85 Nees ye GOAAL. P32, 393: Grass, 2 plants. 


1 Watering as in ordinary nursery practice. 
2 Germination exceptionally rapid. 
3“ Abundant’ indicates usually 100 or more plants per plat; “frequent” indicates 20 or more ;‘‘common”’ 
_ indicates intermediate numbers. All plats measured 2 by 4 feet. 
_ 4 Watering very frequent. 
5 Plats covered tightly for 3 days after treatment to prevent too early evaporation. 


, 
, 


24 BULLETIN 169, U. S. DEPARTMENT OF AGRICULTURE. 


TABLE VI.—Injury to pines and weeds by miscellaneous disinfectants—Continued. 


Days from 
Disinfectant. treatment 
to— 
Plat. pee sant Injury to pines. eae in 
oot. 7 
Substance |  ——_—sd| Sow-- wees 
used. ing. | ati 2 
Bola ation. 
Ounces tion, 
P. divaricata:1 Pints. 
Series..508..(7 || None. . 2265.2). -2-e sce) sae ceel eeelse ep eerelons cease eee anaes Grass abundant; 
checks). Mollugo, Portula- 


ca, Amaranthus, 
and Euphorbia 
follow the 
order named. 


IN ces Sees Formalin?. . 0.375 | 3 8 ; 
Poo Scepeiel sees do.. 375 | 2 8 
Mee eeesefeeees do... 562] 4.5] 8 Grass, 8 or 10plants 
brushes ES eae OU. a ae in each forma 
Dore aot do. 75 | 3 10 | 43-51. -| None detected. plat; other spe- 
Ch hp eee. Was Ne vd Coulee eae 75 3 6 cies rare. 
|S psf eee ages yer ae sae pe ceOe 8 14 
Waste come lvebeine MOE esecee 1.00 4 14 
cs. 2 oes Sulphuricacid| .25 2 9 | 43-51..| Moderate. .......- Grass, 3 plants. | 
Sheed es es el GOs 22 ea ora) ee 9 | 48-51..]...-. rs Coleen Se) None. 
Series 612% (6 | None. . 3.220 42 52. oe | se eee ed ace te ee Mollugo, common; 
checks). grass, Portulaca 
Amaranthus,and 
; Euphorbia fol- 
low in the order 
named. 
Fe are abaiad Hydrochloric . 25 2 10 None.'. .3.--+28 ee Grass, a dozen or 
acid. more plants; Por- 
tulaca and Eu- 
phorbia still less 
: abundant. 
CR ta RS a a ri Co Peg 46y(ae| Cor: 10 Very slight........ Grass, 16 plants; 
Portulaca, 2; Eu- 
47-48. . phorbia, 2. 
: b Yapeee ee) Re: do .562 | 3 10 Slight to moderate.| Grass, 4 plants; 
Portulaca, 2; 
Mollugo, 1. 
ON eee do. 75 | 4 10 «00.2 isc. See Grass, 6 plants; 
Portulaca, 2. 
Coen ceae. Nitric acid. .- 75 3 10 Moderate. . ... ----| Grass, 4 plants; un- 
, known, 1. 
EP ohana fag coe vi aes 1.00 4 10 Very slight........ Grass, 3 plants. 
Ne RY Sul p huric S28) lkx3 11 Very heavy....--- None. 
acid.4 
5 AE a ba Coleen == 375 | 4 11 Heavy co: 2: 2eees Do. 
i. Ls sed Ue eae do.. 688 | 5.5 11 Moderate......-.. Do. 
Pi oie GH GO. thea sh sC88.4 re 11 4.600% eee Do. 
Series 5145 (5 | None..........]. 20... -|------]- an dbalon es cee e|nnewsine he sige mae Grass abundant, 
checks. followed by Mol- 
lugo, Euphorbia, © 


Portulaca, an 
Amaranthus in. 


the order named. 

i try se ret Age asa B63) 2 13 42 | None...........-.-- ——- 14 Pca 

acid. ollugo, 3 or 4. 

Beas dos cae Me Na 13 42 | Slight..........--. Grass, 11 plants; 
Moliugo and Eu- 
phorbia, several 

- plants around 

edge of plat. 

A cee ete Sulphuric acid { 2 : 7. \ 42 | Heavy; 4 affected..| None. 

(Re hay a dome ssces { is 0 \ 42 | Heavy; 4 affected. . Do. 

SRS al ed I BOs csi { 195! 9 0 \ OF eee 0 su ssaetes vee Do. 


‘1 Watered daily, 0.3 to 0.4 inch. 
2 Plats covered tightly for 3 days after treatment to prevent too early evaporation. 
3 Watered daily; dry at surface on date of examination. 
4 This plat became extra dry at time of germination. 
5 Watered daily, 0.15 to 0.3 inch, until 3 days before germination. Surface dry at that time; watering 
done twice daily thereafter. 


INJURY BY DISINFECTANTS TO SEEDS AND ROOTS. 25 


TABLE VI.—Injury to pines and weeds by miscellaneous disinfectants—Continued. 


Days from 
Disinfectant. treatment 
to— 
Plat. Per square Injury to pines. eae in 
a oot. ‘ 
Substance Sow- viced: 
used. ae ing. | nation. 
Ounces.| Fon 
iP. pee 10%. cae a ae ria Grassy, ee 2 20 
tinued. phuricaci : 13 plants; Euphor- 
dear Air-slaked |f .25 |...... 8 \ 42 | None.........--.-- bia and Portu- 
lime. x laca, 1 = 2 Rack 
; Copperacetatel) om} 3 ap ) ae gees 
| Pyle eee {ai laked ee ec a 8 \ 42 | Slight or none..... fn: much less vig- 
c orous condition. 
Pee EEE NONGS coe oc.5 =| < ose eate la ci Pate = [ose alawe co ood loc Gh s ce noeceemerctle Grass abundant, 
checks). followed by Mol- 
4 lugo, Portulaca, 
and Euphorbiain 
: the order named. 
By, cha eho iy rena - 562 3 0 28 (2) Grass, 4 plants. 
acid. 
0 ae Nitric acid....|  .562 3 17 454 NONOl. 22. 2aecr! Grass, 12 plants; 
Mollugo, nearly 
ey, same number. 
Do away! Sulphuric acid . 188 2 0 28 iil aiacs<8 i a re Grass, 2 plants. 
[A es ee OOo Sach . 281 3 0 pg SA BO eas vanartee 2: None. 
PmPEMeRUOMIMNOUOG) 2s cioe 5 Si 28 ck silt ok leone [ene ob cto lecccmiepemae metas clk Grass abundant, 
checks). strongly predom- 


inating; Mollugo, 
Portulaca, Ama- 
ranthus, and Eu- 
phorbia follow in 
: the order named. 
atte. SS. Formalin 4....|  .375 3 a7 45) Non@sccccees 224 58% Grass, 14 plants; 
Mollugo, nearly 
as many; Ama- 
ranthus, 2 or 3. 
ne Goes: ok . 562 3 17 rte ara GOw se eae ses Grass and Mollugo, 
a dozen plants; 
Amaranthus, 2. 


Le ey ae BOE te. Sopa 1.00 4 1¥, Se ee G0. 2 neessees- Grass, 4 or 5 plants; 
4 Mollugo, 4. 
te ae pccarie chlo- | .063 eae GN ina me Oem ante Grass frequent. 
rid. F 
el See 063 Grass, 5 or 6 
Prsttvers Sodium chlo- "188 \ 2 1? ee eres (0s eect geachpae op plants; Mollugo, 
rid. z e a anppipeah se 
: early as many as 
: <0 Spal chlo-)) 994 ee i. F in nearest checks, 
wieleiaes dt. aor. bee Ose Sa ve ae ut larger pro- 
“asl aked |/ 094 o| 2 portion of grass 
apa than in check. 
en Zincchlorid...| .281 3 17 AN es ci Oete See: Grass, 4 plants; 
Mollugo, 1. . 
pene ee Copper sul- . 188 3 7 45 | Slight, or none....| Grass, 9 plants; 
phate. — Mollugo, 2. 
af eee Hydrochloric 375 2 0 28' | -None..:..25--.--5- Grass, 10 or 12 
acid, — plants. 
F...<.....| Nitric acid....|  .562 3 17 45 bs sis AO: 2o satan opr More grass than in 
P; Mollugo and 
Amaranthus also 
Pee present. 
Oss age.¢ Sulphuric acid ~125 2 0 28: He vas; GOs i. 43. Fass. Practically the 
same as in near- 
est check. 


1 Watered 0.3 inch twice daily. 

2 A little at a margin missed in watering. 

3 Watered 0.3 inch, usually twice daily; surface of plats never allowed to become dry. 
4 Plats covered tightly for 3 days after treatment to prevent too early evaporation. 


26 BULLETIN 169, U. S. DEPARTMENT OF AGRICULTURE. 


TABLE VI.—Jnjury to pines and weeds by miscellaneous disinfectants—Continued, 


Days from 
Disinfectant. treatment 
to— 
Plat. Ee sau? Injury to pines. Weeds er in 
oot. ‘ r 
Substance | sd Sow cen 
used. ing. nati 
Solu- hs 
Ounces tio 
P. divaricata: 1 Pints. 
Barres p19" (6 |: None, .. 2.5. -2|--<-5=2]-cae seo ssb ale se= Be ateme te pee gaan eee Mollugo very 
checks). pete a f ol - 
owed by 
Amara ane, 
Portulaca, an d 
Euphorbia in the 
order named. 
SOAS ered op ae Ammonia 2....} 0.5 2 34 66 | Record lost.......| As in checks. 
hss See poste chlo- . 063 2 0 32 (8) None. 
rid. 
SAS (err aaies . 063 P 
otk bees. + Sodium ‘chlo | 1188 Ham acts 32 | Allseed killed....| Do. 
rid. 
R........| Lime-sulphur .313 2 0 32 | Three-fourths of | Records lost. 
the seed killed 
by unknown 
factor. 
lisp h bie Bs Pie OO 25 Saas 75 2 0 32 | Germination good.| None. 
1 ae Ferrous  sul- 5 2 0 32 | Record lost....... Nearly as many as 
phate. in checks. 
eS By Cape sul- . 281 3 34 66 | Moderate to heavy: Do. 
phate. 
A ee Hydrochlori c . 562 3 0 32 | Very heavy....... Grass, very few 
acid. = at edge of 
Moga © Nitric acid....] 1.125] 3 34 66 | Record lost... .-..|) = aim 
Bee (6 epee . 188 : 
O...------\Sulphuricacid| [125] 1] 0 \ 32] Very slight........ Do. 
es eee DO oodinc oe 25 2 34 66 | Record lost.......| Grass and Mollugo, 
each 7 or 8 plants; 
Amaranthus, 1. 
DSS PSNI nce? 0275528 25 3 34 OO Ts See d0i 522 eet Grass, 3 plants. 
ORS). REIS bake a ae ae 375 3 34 664.2235 oO ee Grass, 7 or 8 plants. 
BBNSHIH.. 2 Heat, 80° C. or CN tae Few 32.1 Nome. ..i5.ccaeeken Grass, 7 or 8 plants; 
greater for Portulaca, 1 or 2. 
not less than 
10 minutes. 
Ge ae Bd O) Soccer IG) epee pene Few S24 ance 0}. 25 «ce See Same as for H. 


1 Watered 0.3 inch, twice daily. 
2 Plats covered tightly for 3 days after treatment to prevent too early evaporation. 
3 Nearly all seed killed; heavy injury to those which germinated. 

4 Upper 24 inches of soil heated. 

5 Upper 6 inches of soil heated. 


DISCUSSION OF MISCELLANEOUS DISINFECTANTS. 


HYDROCHLORIC AND NITRIC ACIDS. 


Hydrochloric and nitric acids were used in series 501, plats C and 
J; 512, plats A, C, D, F, G, and K; 514, plats F and G; 516, plats 
A and C; 518, plats F and P; and 519, plats M, O, and P (Table VI). 
Injury by them seems to take place in just the same way as that 
caused by sulphuric acid, and the injured seedlings presented the 
same appearance as those injured by sulphuric acid. (See Pl. I, 
figs. 2 and 3.) Pine seeds were not killed by the amounts used at 
sowing, but the apices of the radicles in some plats were killed by 
the acid residue in the surface soil after germination began. Injury 
may be prevented, as with sulphuric acid, by waterings sufficiently 
frequent to prevent the concentration of the acid in the surface soil, 


INJURY BY DISINFECTANTS TO SEEDS AND ROOTS. 27 


Volume for volume, the hydrochloric and nitric acids used did not 
seem to differ greatly in their effect on the pine seedlings or weeds, 
the hydrochloric acid appearing rather the more dangerous. The 
tests offer little opportunity for direct comparison. As with sul- 
phuric acid, pines were less injured than weeds, and the grasses pres- 
ent seemed more resistant than the dicotyledons. The difference 
in the effect on jack pine, grasses, and Mollugo verticillata shows 
especially well in series 512 and 519, in whose checks Mollugo was 
the most common weed. 

The tests show clearly the low toxicity of these acids in this soil 
as compared with sulphuric acid, volume for volume. Comparison 
of plats C and J of series 501 with plats B, D, and H in the same 
series indicates that sulphuric acid is three or more times as danger- 
ous to both pines and weeds as nitric acid and much more dan- 
gerous than hydrochloric acid. In series 512, sulphuric acid seems 
two or three times as active against the pines as the other two acids, 
while the disparity in the action on weeds appears still greater. In 
series 516, results in plats A and D treated at the same time indicate 
that sulphuric and hydrochloric acids are equally toxic to the weeds 
when the amount of hydrochloric acid used is three times the amount 
of sulphuric. In series 518, plats P and Q, 0.375 ounce of hydro- 
chloric acid per square foot appeared considerably more active 
against weeds than 0.125 ounce of sulphuric acid used on the adja- 
cent plat. Weight for weight, the disparity between the two acids 
is much less. While the strengths of the acids used were not deter- 
mined, a statement of the amounts used indicating relative concen- 
trations of ionic hydrogen would have further decreased and might 
have entirely obliterated the apparent disparity in action between 
the three acids, as was found by Kahlenberg, True,? and Heald 3 in 
their work with these acids in water culture. For instance, using 


__. for comparison sulphuric acid containing 90 per cent H,SO, and mak- 


ing no allowance for impurities, nitric acid containing 60 per cent 
HNO, would contain, volume for volume, but 43 per cent as much 
ionic hydrogen, and 30 per cent hydrochloric acid but 31 per cent 
as much, assuming equally complete dissociation in the dilute solu- 
tions of the three acids. 

TOXIC SALTS. 


| Copper sulphate, tested. only twice, gave rather contradictory 
_ results. In series 518, plat G (TableVI), 0.188 ounce per square foot 
17 days before sowing caused little or no injury to pines and consid- 


1 Kahlenberg, Louis, and True, R.H. On the toxic action of dissolved salts and their electrolytic disso- 
ciation. In Bot. Gaz., v. 22, no. 2, p. 81-124, 1896. 

2True,R.H. The toxic action ofa series of acids and of their sodium salts on Lupinus albus. Jn Amer, 
Jour. Sci., ser. 4, v. 9, no, 51, p. 183-192, 1900. 

8 Heald, F.D. On the toxic effect of dilute solutions of acids and salts upon plants. Jn Bot. Gaz., v. 
22, no. 2, 1896, p. 130. 


28 BULLETIN 169, U. S. DEPARTMENT OF AGRICULTURE. 


erable injury to weeds, while in series 519, plat K, an amount 50 


per cent greater, 34 days before sowing, with more frequent water- — 


ing, caused considerable injury to pines and had little effect on weeds. 
Copper sulphate injured pines just as did the acids, by stopping 
elongation of the radicles shortly after they emerged from the seed. 
Recovery took place in many cases. A marked case of the production 
of laterals in recovery from copper-sulphate injury is seen in a seed- 


ling taken by Dr. T. C. Merrill from a bed in a similar soil at Garden 4 


City, Kans., which had been treated heavily with copper sulphate at 


sowing and again after germination (fig. 2). Normal yellow pine at — 


this age should have a single straight taproot going down at least 


five times as far as the one figured and with relatively little develop- 


ment of laterals. Ferrous sulphate (series 519, plat L) gave little 
- evidence of toxic action in the soil as compared with other substances 
used. Further tests are necessary to give comparable data as to the 
behavior of copper acetate in the soil and the effect of lime in pre- 
venting injury by copper salts, the test made (series 514, plat P) 


being insufficient. The results in series 518, plat N, indicate that — 


zinc chlorid is as dangerous to weed roots in this soil as copper sul- 
phate, or slightly less dangerous. 
Mercuric chlorid in the amounts used acts differently from any of 


the substances previously mentioned, in that it kills dormant pine © 


seed in the soil at Halsey at the time of application. In series 519, 
plat V (Table VI), the seeds which failed to germinate were taken out of 
the soil and carefully examined, both with a hand lens and with a com- 
pound microscope. No indication was found that they had ever com- 
menced germination. The difference is presumably due to greater 
penetrative power. Mercuric chlorid in the soil is injurious both to 
the roots of seedling pines and to weeds in quantities, which in the 
case of the other salts tested would have no effect. The addition of 


common salt to the mercuric chlorid at the time of application | 


appears to increase the damage it does in the soil, possibly by delaying 
the entire breaking down of the disinfectant until it has time to act 
on the plants. (Compare 518-C and 519-U with 518—-D and 519-V.) 
The additional toxic effect could hardly have been directly due to the 
0.188 ounce of common salt per square foot applied, since 0.2 ounce 
of salt per square foot applied dry to a jack-pine bed three or four 
days before sowing in an earlier series had no effect on the pines or on 
the grass and Mollugo common in the series. The addition of sodium 
chlorid also makes the disinfectant more convenient to work with by 
greatly in¢reasing the rapidity of solution. The addition to series 
518, plat A, of an amount of air-slaked lime equal in weight to the 
mercuric chlorid applied four days earlier prevented most of the 
injury to weeds which occurred with smaller amounts of the chlorid 
in plats not limed. 


a a ee ee, ee ee ee 


ee ee ee eS ee ee eee 


INJURY BY DISINFECTANTS TO SEEDS AND ROOTS. 29° 


With these salts, as with thé acids, the pines appeared on the whole 
more resistant to toxic action than the angiosperms present. There 
was less evidence in the experiments of a difference in susceptibility 
to salts in general between the grasses and the dicotyledons. Heald’s 
tests of the resistance of corn and peas to copper salts! showed for 
these plants a reversal of their relative resistance to acid, the peas 
being able to grow in twice as strong copper solution as corn, whereas 
with four mineral acids they could grow in solutions only one-fourth 
as strong. 

Ammoniacal copper carbonate was also used with jack pine. A 
plat of this pine was given a solution made up of 0.006 ounce of 
copper carbonate and 0.099 fluid ounce of ammonia per square foot 
the first day after germination, and this was repeated two days later. 
Hight. days after germination the plat was again treated, using 0.014 
ounce of carbonate and 0.22 ounce of ammonia per square foot. 


Practically all the seedlings were killed by these treatments. Most 


of the injury appeared to be done by the first two applications, in 
which a total of 0.012 ounce of carbonate per square foot was ap- 
plied. This plat, which received a total of 0.026 ounce of copper 


- carbonate, was resown 16 days after the last application. No serious 


injury occurred to the second sowing. 

Another plat treated just before sowing (plat 60, Table VI) fur- 
ther indicated a very great toxicity for ammoniacal copper carbonate 
if only the amount of copper contained is considered. The injury 
to pine in this plat was much more severe than in plat 64, which had 
been treated with sulphuric acid more than 25 times the weight of 
the copper carbonate used on plat 60. It is probable that the 
extremely toxic action of this fungicide was due more to the action of 
the ammonia than to the copper. The known tendency of ammonia 
to prevent the precipitation of copper salts from solution may, how- 
ever, result: in more prolonged activity of the copper in this disin- 
fectant than when simple aqueous solutions of copper salts are applied 
to the soil. 

_FORMALIN. 


Like mercuric chlorid, formalin is capable of killing seed outright 


if applied at the time of sowing. In a test of yellow pine in which 


the disinfectant was applied at sowing (plat 415, Table VI) most of > 
the seeds were killed before they gave any outward evidence of 
commencing to germinate. So far as could be learned, those which 


were able to start germination were uninjured. In plat 416 (Table 


VI), which received the same amount of formalin, half at the time 
of sowing and half at an interval of a month earlier, no injury could 
be detected. In all other cases, formalin was applied several days 


1 Heald, F. D. Op. cit., p. 152. 


30 BULLETIN 169, U. S. DEPARTMENT OF AGRICULTURE. 


before sowing and did no perceptible damage to pines or pine seed. 
This was true even in series 508, plat G, in which 0.75 fluid ounce per 
square foot was applied six days before sowing and evaporation 
allowed for only three days before sowing. The effect of formalin on 
the weed stand seemed approximately equivalent to that obtained 
with one-half or one-third the volume of sulphuric acid. As the 
weight of H,SO, per fluid ounce of acid used was at least four times 
as great as the weight of HCHO in the formalin, the formaldehyde 
appears rather more effective, weight for weight, in keeping down 
weeds. The radical difference in the type of action of the formalin 
against the pines renders impossible any direct comparison with acid. 


LIME-SULPHUR SOLUTION. 


The results in series 519, plats R and S (Table VI), are contra- 
dictory. Injury to pines from fairly heavy applications of lime-sulphur 
at the time of sowing can probably be prevented by sufficient water- 
ing during the germination period. The injury to weeds occurred 
despite heavy watering. 


EXPERIMENTS AT MORRISVILLE, PA. 


During the season of 1912, in pursuance of recommendations by 
the writer, tests with sulphuric acid were conducted by Mr. R. E. 
Lee, under the direction of Mr. John Foley, forester of the Pennsyl- 
vania Railroad, at the nursery near Morrisville, Pa. Sulphuric acid 
only was used. All treatments tested resulted in a decreased stand. 
The results of very weak treatments on beds given ordinary nursery 
watering are shown in Table VII. 


TaBLE VII.—Evidence of injury to pines by sulphuric acid applied at the time of sowing, 
Morrisville, Pa. 


Final | Decrease 


Num- . F 
ber of Sowing | Acid per sane. = eg 
Plat. plats Species. to germi-| square Watering. avernins ita: 
aver- nation. foot. of cheaka |calees ts 
aged. as acid 
Days. | Fluid oz. Per cent. 
1 | Pinus ponderosa....} 6to 9 ~ 0.031 91 9 
Series 631.. MD ihe. yee Ye (se ee eee Sane 6to 9 . 042 95 5 
8 fedecs Go. cbt ake 6to 9 - 083 90 10 
Series 632.. 16 | Pinus resinosa...... 9 to 10 . 083 55 45 
Series 633.. 21 | Pinus strobus....... 16 to 21 . 083 27 73 
Series 634. . 7 | Pinus sylvestris. ...- 7 .083 }|}Only as in ordi- 74 26 
Series 635... | a ee fs a reek & Rae 9 to 12 - 083 nary nursery 63 37 
Series 636. . 7 | Picea excelsa.......- 11 . 083 practice, 56 44 
Series 637. . 14 | Pinus sylvestris... .- 8 to 10 . 083 62 38 
Series 638: 
EB 1 ee fe GG. Mees t eae ale eae . 188 34 66 
Diao, cuts lL yeceekt GOEL wesetise. leds cee . 25 26 74 
a oe aety Us 2 SLipalpts arRait Meine Anes 375 a 
5:0 Sk Ute OAC SS erie mr MERE Mae aed, fry 4 . 188 P . ; 17 
Teh Pat: Meee een Pie liber: id barged : £ ae (eae eet tem 53 47 
Rbyele t | beets Gest. Sia. ee 375 y: 


Cy ie 


Zz 


Orie 


* eee *. Tees, 


INJURY BY DISINFECTANTS TO SEEDS AND ROOTS. 31 


The relative resistance of Pinus ponderosa to the acid is probably 
due to its rapid growth, as at Halsey. The severe injury to P. strobus 
is rather surprising in view of the length of time which elapsed before 
germination. The consistent relation in series 638 between the de- 
_ crease in stand and the amount of acid used and the evidently helpful 
_ effect of frequent watering leave no reasonable doubt as to the agency 
of the acid in causing the decreased stand. In all of the series ex- 
cept 631 the treated plats were uniformly poorer than the checks. 
In series 638, fewer seedlings appeared in acid plats than in the 
checks in all cases, the deficiency being greatest in the ordinary 
watering plats, and the amount of death just after the seedlings came 
up in the ordinary watering plats was very large. The amount of 
germination and early loss for the other series was not determined. 
_ The evidence of the experiments at Morrisville as a whole shows 
that at this nursery the amounts of acid necessary to cause injury 
were much smaller than at Halsey. 


GENERAL DISCUSSION AND CONCLUSION. 


It is evident that the toxicity of disinfectants to the roots of plants 
in soil at Halsey, Nebr., varies greatly in response to a number of 
different factors. The amounts of water in different parts of the 
soil at different times and the movements of soil water, which result 
‘in concentrating the soil solution at particular points, must be con- 
‘sidered, as well as the concentration of the solution applied. The 
depth of the root tips in the soil at the time of greatest concentration 
of the soil solution is also of prime importance, and the time of appli- 
—eation is a very important variable. 

In general, while it is evident that disinfectants do not act on plant 
roots in soil to the same extent as in liquid cultures, they seem to 
act in much the same way. If only the free poison in the soil solution 
is considered, it is doubtful whether a great difference in degree of | 
toxicity can be found in soil and in liquid cultures. However, the 

activity of poisons in the soil solution should not be expected to 

equal their activity in pure water cultures. Antitoxic relations 

which have been found by various workers to exist between numerous 

substances in water cultures may be expected to exist between most 

disinfectants and various components of the soil solution. An in- 
vestigation of antagonism between substances obtained in soil ex- 

tracts and some of the substances used in soil disinfection should 

yield some interesting results. Most poisons are of necessity rather 

unstable substances, and even where leaching is prevented, as in 

pot experiments, and nonvolatile substances are used, the loss of 

free poisons from the soil solution by combination with soil con- 

‘Stituents and by other absorptive processes is undoubtedly great. 


32 BULLETIN 169, U. S. DEPARTMENT OF AGRICULTURE. / 


That acid solutions, in fact, are much more toxic just after applica- 
tion is clearly shown by the experiments at Halsey. That the 
rapidity with which disinfectants are rendered inactive in the soil 
should vary greatly in different soils is to be expected, in view of the 
great differences which exist in both their physical and chemical 


constitution. However, examinations of soils by the usual methods 


of chemical and physical analyses and lime requirement and wilting- 
coefficient determination do not give much indication as to how sul- 


phuric acid may be expected to behave in different soils. A soil with 


a low wilting coefficient may be expected to have a rather low aver- — 
age water content under field conditions and therefore to require — 
small amounts of disinfectants to raise the soil solution to a killing — 
concentration. Coarse texture indicates low absorptive power and — 


a consequent small capacity for disinfectants without injury to roots. 
A high lime requirement may indicate soil acidity, but it may also 


be found in a nonacid soil which has high absorptive capacity.! Both — 


on theoretical grounds and from the results obtained at Halsey with 


sulphuric acid and mercuric chlorid treatments followed by lime, - 


the carbonates present should have a decided influence in preventing 
injury by acids, and probably by many toxic salts as well. Experi- 
ments are under way at several nurseries at which preliminary re- 


sults indicated a distinct relation between determinable chemical — 


a Ae ee 


and physical characters and the behavior of disinfectants. But — 
between soils as much alike as those on which the foregoing experi- 


ments were conducted, the physical and chemical examination made 
gives no clue to any difference which can explain the different be- 


en a a 


havior of sulphuric acid on the two. Neither soil yielded CO, by 
the method employed in the examination by the Bureau of Soils. — 
The surface soil at Morrisville contains more CaO, has a higher igni- 
tion loss, a higher wilting coefficient, and a lower lime requirement — 


w 4 


than the Halsey soil, all of which would seem to indicate a greater 


capacity for acid at Morrisville. The experiments show throughout — 
that the reverse is the case. While the tests made at the two nur- — 
series are not absolutely comparable, comparison of the plats of — 


series 501 (Table VI), which received from 0.125 to 0.25 ounce per 


5 


square foot, with series 631 to 637 inclusive (Table VII), in which ~ 
from 0.031 to 0.083 ounce was used, indicates that at Halsey the 


amount of acid required to cause injury is three times that required 


~- 


at Morrisville. It seems probable, in view of the semiarid conditions — 
at Halsey, that the Morrisville soil was more acid or less alkaline than — 


the Halsey soil. 


An attempt to get an indication of different reaction between the ; 
two soils a year after the samples were taken failed, both soils giving ~ 


1Cameron, F. K. The Soil Solution, the Nutrient Medium for Plant Growth, p. 65, footnote1. Easton, 
Pa., 1911. ; 


fa es ee 


INJURY BY DISINFECTANTS TO SEEDS AND ROOTS. 88 


negative results with the potassium nitrate and iodin test outlined 
by Loew! and turning blue litmus red, the latter phenomenon 
likely indicating absorption rather than acid reaction for either 
soil.? Titration of extracts from fresh samples of these soils should 
give more indication of the real cause of the different behavior of 
acid at the two places. If difference in reaction of the two soils 
explains the different results, it is probable that the difference in 
capacity for disinfectants would be less marked or even reversed with 
such disinfectants as copper sulphate. 

Further evidence of the failure of chemical analysis or physical 
characters to show what action disinfectants will have on roots in 
different soils is seen in the difference between the results in these 
nursery soils and the results obtained by Lipman and Wilson * with 
a soil described as sandy and having a chemical constitution showing 
no very radical differences from those reported in the foregoing. 
On this soil they found that there was no evidence of damage to 
either wheat or vetch seedlings by sulphuric acid in the amount of 
600 parts per million of water-free soil applied several days before 
sowing. While these experiments, conducted in pots, can not be 
directly compared with those of the writer, it is sufficiently evident 
that the results are very different. At Halsey, 0.125 fluid ounce 
per square foot, followed by the ordinary watering given germinating 
seed beds, entirely prevented the growth for at least a month after 
application of the monocotyledonous and dicotyledonous weeds rep- 
resented in the seed beds. Assigning to the commercial acid used 
@ maximum strength, which may be assumed as having a specific 
gravity of 1.84 and purity of 95 per cent, and to the soil a minimum 
weight, which for this fine sand may be taken as 80 pounds per cubic 
foot, we find that even if all the acid applied were held in the upper 
4 inches of soil the weight of H,SO, used was only 534 parts per mil- 
lion of soil. That this treatment should have prevented all growth 
of weeds, in which both monocotyledons and dicotyledons were repre- 
sented, while 600 parts did not even decrease the growth rate of 
wheat and vetch on the soil used by Lipman and Wilson, indicates 
a very considerable difference in behavior of acid in the two soils. 
As injury to pines is caused on the Morrisville soil by amounts of 
acid only one-third of that required to injure pines at Halsey, the 
contrast in the results between the Morrisville soil and that used by 
Lipman and Wilson is still more marked. 

_ The observations made by the writer on the species of Equisetum, 
pines, grasses, and dicotyledons most common in the seed beds at 
1 Loew, Oscar. Studies on acid soils of Porto Rico. Porto Rico Agr. Exp. Sta. Bul. 13, p. 6, 1913. 
-2Cameron, F. K. Op. cit., p. 66. 


%Lipman, C. B., and Wilson, F. H. Toxic inorganic salts and acids as affecting plant growth, In 
Bot. Gaz., v. 55, no. 6, p. 409-420, 1913. 


34 BULLETIN 169, U. S. DEPARTMENT OF AGRICULTURE. 


Halsey indicated a considerable variation in resistance to sulphuric — 
acid between species of these four phylogenetic groups, exceeding ~ 
the variation between different species in the same group. It further — 
appeared that, for the four main groups represented, the higher the 
group in the evolutionary scale the greater the susceptibility of its 
representatives to injury, not only by sulphuric acid but by hydro- — 
chloric and nitric acids and by some of the toxic salts. It is under- — 
stood, of course, that these differences would not be expected to — 
obtain with all species of these groups, and parallel water-culture 
tests with the species observed by the writer would probably show 
that some of the differences in susceptibility indicated in the nursery 
tests were due to other factors than variable protoplasmic resistance. 
The experiments reported in the foregoing were devised primarily for ~ 
developing disease-control methods, and interpretation of many of © 
the direct effects on the seedlings is of necessity difficult. : 

From the practical standpoint, it seems probable that sulphuric — 
acid can not be used alone as a disinfectant for sandy soil soon to be — 
sown with truck crops. This is at least true if the plants to be grown > 
prove as susceptible to acid injury as the dicotyledonous weeds © 
encountered in these experiments seemed to be. However, acid can ~ 
probably be applied with safety on most soils several days before 
sowing if air-slaked lime sufficient to counteract three-fifths or more — 
of the acid used is raked into the surface soil just before seed sowing. — 
Sulphuric acid is so much cheaper than formalin that if subsequent 
lime neutralization is found practicable this acid may in many cases ~ 
supplant both heat and formaldehyde as a soil disinfectant for work — 
in which immediate reinfection with parasites is not feared. The 
writer’s experience indicates that, aside from the destruction of — 
parasites, soil treatment with acid followed by lime results in a 
considerable increase in the growth of many plants, in some cases — 
being more prompt and marked than that following heat disinfection. — 


SUMMARY. 


Sulphuric, hydrochloric, and nitric acids, and copper sulphet 
used in disinfection of seed-bed soil caused injury to the roots of pine , 
seedlings and prevented the development of many species of angio- © 
spermous weeds. All cause injury to pines by killing the growing © 
apex of the radicle immediately after the seed germinates. They ~ 
can be used to disinfect pine seed beds only if the operator knows how — 
to recognize and prevent such injury to the pines. Typical healthy — 
and acid-injured seedlings are shown in Plate I, figures 1, 2, and 3, — 
and a method by which injured seedlings can be distingeiates from ’ 
others is described on page 9. Many injured seedlings later resume — 
root growth and recover (PI. I, fig- 4, and text figs. 1 and 2). Injury © 
is due to the concentration of the disinfectant in the surface soil 


~ 


INJURY BY DISINFECTANTS TO SEEDS AND ROOTS. 35 


consequent on the capillary rise of the soil solution and the evaporation | 
of water from the soil surface. It is found that in a sandy Nebraska 
soil all injury can be prevented by very frequent watering during the 
germinating period (pp. 11-12). It can also be prevented in the case 
of acid applications by adding lime to the soil shortly after treating 
with the disinfectant (pp. 21-22). The lime method, while undesir- 
able in the case of pines, is probably the only one which will prevent 
injury to angiospermous seedlings. The acids can be applied to seed 


_ beds at the time of sowing without any injury to dormant pine seed. 


Formaldehyde and mercuric chlorid in sufficient disinfecting strengths 
must be used several days before seed sowing, as they are able to kill 
dormant pine seed in the soil. Formaldehyde applied at or before 
seed sowing never causes the injury to germinating pines that is 
caused by the acids and salts. 


ADDITIONAL COPIES 


OF THIS PUBLICATION MAY BE PROCURED FROM 
THE SUPERINTENDENT OF DOCUMENTS 
GOVERNMENT PRINTING OFFICE 
WASHINGTON, D. C. 

AT 


5 CENTS PER COPY 
Vv 


WASHINGTON : GOVERNMENT PRINTING OFFICH : 1915 


et 
t 


Be vs thane 2 ai dul | 43 banot PE 
z ee. a ee 


: 
’ ‘ me 
ee ‘ =e 5 vi “f it adie < J 
¢ { y beet Py te - Chr Seer 
: = } ' @ | pra: M 
iF = 
om 4 
‘ aa 
, 4 af 
. ht , 3 
* 
uy e® 
\ z 
Fs 
¥ 4 
a 
“i \ 
’ 
= - 
_ ir , 
e 
,. 
iy . o 
4 
se 
J ~ 
; 7 
’ 
ia - 
ava - 
1 rt 4 ‘ 
¢ 
. 
‘ + x 
* 
‘ 
i 4 5 
e 
. ; 
* . = ‘ ‘ 
4 big ~ mh 
. ~ 
y 4 7 - . y 
i ns 
Mf - ; 
‘ e y 
‘ ~ —~ & 
7 i * 
“ 
~* ” 7 mt -_ 
= ‘ 4 >. 
i 4 —< — 
r. : - 
f _ . + 1 * } oe “; 
' | ar. as et ae ‘ sad “th ¢; 
rar? Seto aver ia we eee POD) POT hae 
5 4 
* ¥ x 
- 1 sit 7 ’ 
, f rs 


Pees LLIN OP TELE 


an Y + 
€ J} USDEPARINENT OFAQRICULTURE * ie? 
oe No. 212 KGa 


Contribution from the Bureau of Plant Industry, Wm. A. Taylor, Chief. 
May 26, 1915. 


(PROFESSIONAL PAPER.) 


OBSERVATIONS ON THE PATHOLOGY OF 
THE JACK PINE. 


By James R. WEIR, 
Forest Pathologist, Office of Investigations in Forest Pathology. 


INTRODUCTION. 


A discussion of the fungous diseases of a particular forest tree is 
incomplete unless the general habitat in which the tree grows and 
which influences the occurrence and virulence of its diseases is con- 
sidered. In general, a description of the characteristic home of the 
jack pine (Pinus divaricata (Ait.) Du Mont. de Cours.) is essentially 
that of the sandy plains in the region of the Great Lakes, where it 
attains its greatest size. Here the sand deposits are usually of great 
thickness and heavily mixed with glacial drift. The soil is composed 
chiefly of the same materials. With the exception cf some of the 
lower plains and old lake levels the humus soil is very thin. In most 
- regions within the range of the jack pine there is practically no humus. 
Where humus does exist in any appreciable thickness it is so much a 
part of the underlying sand and gravel that it dries out very rapidly, 
affording no opportunity for a luxuriant and uniform forest cover. 
Exceptions to this occur in parts of Minnesota and Canada. The 
improvement in the quality of the soil is at once reflected by the larger 
size of the jack pine and incidentally in the nature and virulence of 
the diseases attacking it. Observations show that a continuous and 
sustained growth in the case of the jack pine is not conducive to much 
injury from wood-destroying fungi. 

_ Owing to the rapidity with which the soil of the jack-pine ‘‘plains”’ 
dries out and to the inflammable nature of the slight ground cover, 
favorable conditions are furnished for forest fires. This, in turn, 
likewise greatly influences the presence of fungous diseases as a result 
of injuries caused by the fires. Severe and rapid changes in temper- 
ature and a fluctuation of the mean annual precipitation are other 
factors characteristic of the jack-pine habitat. The susceptibility of 
forest trees, and likewise of the fungi attacking them, to the influence 
of soil and climate directly or indirectly produces conditions favor- 
25752°—Bull. 212—15 


yy BULLETIN 212, U. S. DEPARTMENT OF AGRICULTURE. 


able or unfavorable to the best development and spread of disease. 


The fungi inhabiting the bark and leaves are probably influenced by — 


these factors in a far greater degree than are those attacking the 
heartwood. 

Pathologically, the jack pine may be divided, in most regions of its 
range, into two forest types, which are determined largely by the 
amount of moisture in the soil. 
The fungi at work in the moist or 
swamp type may occur in the drier 
and more arid type, but may show 
considerable variation in the abun- 
danceofanyonespecies. Another 
factor of considerable importance 
is the absence or presence of any 
associate tree of the type which 
may prove equally or even more 
susceptible to cosmopolitan fungi 
and thus increase the chances of 
infection for all members of the 
stand. In many parts of its range 
the jack pine occurs in purestands. 
In mixture with other species it is 
usually attacked by a greater num- 
ber of diseases than in pure stands. 


DISEASES. 


immediate injury to the jack pine 
of all age classes, as determined by 
pathological surveys in Michigan 
and Minnesota, is Peridermium 
cerebrum Peck (Cronartium quercus 
(Brondeau) Schrot.).1. The galls 
(fig. 1) produced through the stimu- 
DD WIR 2, oo lative effect of the fungus are in 

" Peridermium cerebrum, showing the enaracter. May and June covered with glob- 
istic swellings which extend around themain oid swellings somewhat after the 
er manner of the convolutions of the 


1 Peridermium cerebrum is quite similar to P. harknessii Moore, which causes much damage to Pinus 
contorta (lodgepole pine) in the West. Some recent observations by Hedgcock and Meinecke indicate the 
possible identity of Peridermiwm cerebrum with P. harknessii on Pinus radiata (Phytopathology, vol. 3, 
p. 16,1913). These two Peridermiums are held by Arthur and Kern to be identical (Mycologia, vol. 6, 
no. 3, pp. 133-137, 1914). Cultural experiments by Arthur and Kern (Mycologia, vol. 6, no. 3, pp. 133-137, 
1914) and also by Hedgcock and Long (Journal of Agricultural Research, vol. 2, pp. 247-249, 1914) demon- 
strate the identity of Peridermium fusiforme with P. cerebrum. Peridermium globosum Arthur and Kern 
founded on a single specimen and supposed to occur on Pinus strobus has been acknowledged by the authors 
to be P. cerebrum on Pinus divaricata. The error arose from a misidentification of the. host (Mycologia, 
vol. 6, no. 3, pp. 133-137, 1914). 


The fungus causing the greatest 


Plt ar, - 


PATHOLOGY OF THE JACK PINE. 8 


-brain—cerebroid. These: blisterlike swellings are orange-yellow at 
first; after the rupture of the peridium and the dispersal of the 
golden yellow xciospores they become whitish. The gall formation 
causes great injury to the trunk and branches (fig. 1). The infection 
usually begins by means of some injury to the bark or cambial layer.’ 
The gall swellings gradually increase from year to year from the 
growth of a perennial mycelium, so that they finally encompass the 
entire branch, resulting eventually, if the galls are near the trunk, in 
its death below and 
above the hypertro- 
phy. Whether or 
not the entire branch 
dies depends upon 
the presence of lat- 
eral, leafed branches 
below the gall. 

In dry sandy areas 
Peridermium cere- 
brum confines itself 
more generally to the 
branches, occurring 
rarely on the trunk 
but frequently in the 
axils of the branches. 
This latter condition 
usually results in a 
combination trunk 
and branch gall, 
which in numerous 
instances produces 
greater damage than 
either of the other 
two types of galls. 
The branch and 


Fig. 2.—Cross sections of the main trunk of a jack pine heavily in- 
trunk are girdled by fected with Peridermium cerebrum. Note the progressive girdling 


by the resinous burl tissues in the upper figure and its effects on 


a b norma ] woo d the increment of the trunk below, as shown in the lower figure. 


tissue and are thus 
weakened (fig. 2). This results usually in either the branch or the 
tree being blown down by the wind. Personal observations show 
that borers and wood-rotting fungi entering at the burl often hasten 
the decline of the tree. 

From a careful examination of young twigs showing very recent 
infections at leaf scales, leaf traces, and at the bases of young pistillate 


1 Wounds made by sapsuckers, ovipositors of bark-stinging insects, rodents, and ice and snow breaks 
_ are common means of entrance for Peridermium cerebrum. 


—_s 


4 BULLETIN 212, U. S. DEPARTMENT OF AGRICULTURE. 


flowers, it is believed that Peridermium cerebrum can enter young 
seedlings or the tender portions of more mature growth without first 
having the bark broken. Entrance in this manner must, out of 
necessity, be aided by sufficient moisture for germination and to per- 
mit a rapid penetration by the young mycelium. On the sandy 
plains of the Great Lakes region rain water disappears almost immedi- 
ately and the sand becomes heated about the isolated tree groups, 
causing a rapid evaporation from the surface of the trunk and 
branches and leaving the moisture content of the outer bark at a 
minimum. In whatever manner the fungus may enter its host, 
directly or through wounds, the number of galls and imperfect 
branches is usually much less on trees of the sandy barrens than in 
more moist regions. 

In swampy areas the jack pine grows in close stands. Here the 
percentage of infected trees is much greater. The trunks of the 6 to 
12 year old jack pines are often covered with swellings stunting the 
growth of the trees very rapidly (Pl. I, fig. 1). Trees so infected 
never reach maturity and may continue living for an indefinite 
period in a stunted condition, to be finally blown over by the wind 
or broken down by the snow. The 1 to 4 year old seedlings are quite 
often attacked. With these, as is often the case with larger trees 


which through mechanical injury may become infected at the ground, ~ 
the gall is formed directly at the base of the main stem. When a — 


seedling is infected there or higher up on the stem, it develops into a 
deformed growth after the manner of a witches’-broom (PI. I, fig. 2) 
and never attains a height of more than 2 or 3 feet. The perennial 
mycelium of the fungus thrives in the cambial layer and in the living 


parts of the sapwood. ‘Trees with a single infection on the trunk ~ 
occurring at the age of 4 to 6 years are known to support the living © 


mycelium of the fungus to the advanced age of 70 to 80 years. Usu- 


ally, however, the excessive production of resin in the infected — 


tissues infiltrates the woody portion of the trunk, and the sap supply 
is cut off so that death results in a comparatively short time (fig. 2). 
This is especially true in young seedlings. Peridermium galls are 


b 


frequently observed a foot or more in diameter. Trees supporting — 


galls of this size had succumbed in every instance to the disease. 


Some knowledge of the damage done by Peridermium cerebrum to ~ 


the jack pine may be obtained from notes of a pathological survey 


by the writer in the national forests of Michigan. Out of 100 trees — 
of an average plat on dry sandy soil, not selected because of any © 
pronounced diseased condition, 50 per cent were heavily infected, — 
while only an occasional tree out of a second hundred on similar but — 


moister soil was absolutely free from the disease. Out of 100 trees 
taken from the swamp type, practically all were infected. Not all 
the trees were infected seriously. A tree bearing a single branch gall 


._ = 


—— eee 


Bul. 212, U. S. Dept. of Agriculture. PLATE lI. 


ee 


FIG. 1.—A 6-YEAR-OLD JACK PINE IN- Filia. 2.—FOUR-YEAR-OLD SEEDLINGS 
FECTED WITH PERIDERMIUM CEREBRUM. OF JACK PINE, SHOWING THE CHAR- 
The complete girdling of the main stem by ACTERISTIC SWELLINGS OF PERIDER- 
ae poroetely eponeged pals is shown. MIUM CEREBRUM. 
eee ped gall tissues. The entire crown of the seedlings develops 


into spherical brooms. 


Fic. 3.—VARIOUS TYPES OF INFECTION OF YOUNG JACK PINE BY PERI- 
DERMIUM COMPTONIAE. 


Note that in the central figure the fungus has invaded tlhe underground tissues 
of the stem, 


. , 
Sits Th . > ' pty 
i Cael 
x y . 
bi ye < - 
’ ’ ¥ oe 
i , Y = 
d , : : ¥ / : 
a ee +~ teh, 
s ? f 
7 5 > Ps) 
% ais 
‘ z * 
I “ > < le . 
“ f : z > ; ' , & 
‘ ‘4 ae ] e Ma 
* 4 fi +! 
“y s 
haat ers ‘ 
4 ; j : 
’ } 
: A 
i . i 
: 
4 
‘ 4 
\ ui 
t 


PATHOLOGY OF THE JACK PINE. 5 


was marked ‘‘infected.’”’ Four trees specifically studied yielded by 
actual count an average of 220 burls on the branches and 13 on the 
trunks. The cones produced by these trees, although of average 
number, were small, with a higher percentage of abortive sporophylls 
than is commonly the case with this species (fig. 3). Comparative 
germination tests of seeds from heavily infected and vigorous non- 
infected jack pine of the same age and type conditions showed for 
the former a germination of 19 per cent below that of the latter. For 
this experiment 10 
samples, consisting 
of a dozen or more 
cones, were taken 
from each of five 
heavily infected and 
five uninfected 
pines. Fifty seeds 
from each of these 
samples were plant- 
ed in sand, kept 
moist with distilled 
water, and allowed 
to stand at labora- 
tory temperature 
fabout, 70°. F.) for 
90 days. 

The prolific devel- 
opment of Periderm- 
wm cerebrum in 
many parts of the 
jack-pine forests of 
the Great Lakes 
region is a factor in 
reforestation which 


should be carefully 


A Fic. 3.—Branch of jack pine with aborted cones, the result of a severe 
considered. The attack of Peridermium cerebrum. Note that some of the cones did 
fact that the funcus not open and that most of them are less than an inch in length. 
{ Average normal cones measure from 14 to 2 inches. 


occurs so commonly 
on young seedlings in the natural forest and occasionally in the 
nursery shows that it is a menace to the best development of the 
species. The largest and best formed jack pine in all the regions 
studied where the Peridermium was abundant was almost entirely 
devoid of this injurious disease. However this may be interpreted 
as to the original differences in vigor, the fact that heavily infected 
trees were invariably scrubby and ill formed is, in the mind of 
the writer, directly referable to the effects of the parasite. The 
fact that P. cerebrum has its telial stage on the leaves of several 


6 BULLETIN 212, U. S. DEPARTMENT OF AGRICULTURE. 


‘ 


species of Quercus ' should be of much significence in control work. 


Quercus velutina and Q. coccinea are two scrub oaks frequently form- 
ing a conspicuous part of the jack-pine type, particularly in Michigan. 
Methods could be devised for the eradication of these worthless 
species, thus removing the alternate host of the fungus. However 
impracticable this may be on a large scale, in wood lots and small 
holdings this would not be a very difficult 
matter. The removal of infected branches of 
young growth could be done in the orchard- 
like stands of jack pine on the more sandy 
soils, thus saving many young trees from early 
suppression. re ate 

In a few instances, in the region studied, 
young jack pine was found to be diseased by 
Peridermium comptoniae (Arthur) Orton and 
Adams (Cronartium comptoniae Arthur). 
(Fig. 4.) In the experience of the writer this 
fungus was not common. ‘The ecial stage of 
the fungus is chiefly characterized by a slight 
fusiform swelling, seldom forming the spheri- 
cal gallsso characteristic for P. cerebrum. The 


i 


tinguished from P. cerebrum by attacking 
principally young seedlings (Pl. I, fig. 3) and 
causing excessive brooming of the branches. 


= 
4 
« 
Y 
. 
f y _ 
nail 
% 
gy ee: 
ie 
at | 
aes © 
Ss 
> 3 
‘ 
. we # “. 
r ye 
v So. 
>. i 
> y . 
ad r mn 
or 2 ~ 
. , ae 
x 
.- a 
N ef 
‘ +4 
‘ Z 
. “¢ 
7 : + 
me 
- * 
* ‘ 
Ar % 
> SX. 
€ 
pa A 
au a” 
< 
4 ' 
~ 


all 


, mv 


P. cerebrum attacks both young and old trees. 
P. comptomae has its alternate stage on sweet 
fern ? (Comptonia peregrina and Myrica gale). 


these plants the fungus can not reproduce 
itself on the jack pine. 
As a precaution agains tthese Peridermiums 
entering the forest nursery and the possibility 
Pole ae 2 of their transportation to other regions, all 
Fig. 4.—Young jack pine infected Ss 
with Peridermium comptoniae. alternate hosts, such as species of oaks and 


= 


peridia rupture with a sharply serrate or 
spiny margin. The fungus is further dis- 


It was not found on more mature growth. — 


Without the production of the teliospores on — 


Note the ruptured peridia with sweet ferns, should be removed from the © 


their serrate margins. 


vicinity of the nursery. This immunity zone 
should be extended as far back from the nursery as time and means 
will allow. Before new nurseries are established a pathological sur- 


vey of the immediate region should be made as to the presence of — 
these hetercecious pine rusts. Much attention should also be given — 


1 Demonstrated by Dr. C. L. Shear, Jour. Myc., vol. 12, p. 89, 1906. 
? Demonstrated by G. P. Clinton, Conn. Agr. Exp. Sta. Rept., 1907, pp. 380-383, 1908. 


PATHOLOGY OF THE JACK PINE. 7 


the selection of nursery sites, with regard to sone topography and 


prevailing winds of the region. 


With the exception of Peridermaum cerebrum and P. comptoniae, 
few fungi of economic importance attack the living jack pine in 
the drier parts of its range. On the dry pine barrens of the Lake 
States the jack pine reaches its normal age without much defect 
in the wood arising from fungous diseases, although exceptionally 
old trees of 90 years and more frequently show considerable decay. 
In mixture with other species in the more moist regions of its range, 
particularly in parts of northern Minnesota and of Canada, Trametes 
pint (Brot.) Fr. causes considerable heart-rot in trees of 60 years and 
older. In general, however, this fungus is in negligible quantities. 
~ In close stands jack pine prunes readily during its most rapid growing 
period, forming straight clear stems. The rapid occlusion of the 
branch knots shortens the danger period for infection by wound 
fungi. It is principally due to this fact that some of the most serious 
wood-destroying fungi do not effect an entrance until the tree has 

reached its period of decline. 
Polyporus schweimtzii Fr., causing a butt rot, is usually in greater 

abundance than Trametes primi, but the percentage of infected trees, 
even on the more protected soils, is seldom more than 2 to 4 per cent 
of the stand. The jack pine is a deep-rooted species and unless the 
- root system comes in contact with a hard stratum of clay and gravel, 
- root-destroying fungi are largely a negligible quantity. In this class 
are FKomes annosus Fr. and Armillarva mellea (Vahl.) Quél., which 
_ very rarely occur on the jack pine. Only a few isolated and unim- 
portant infections have ever been recorded by the writer. 
The jack pine does not suffer any material injury from needle 
fungi. Those that do occur are mostly of a saprophytic nature. 
Lophodermium pinastri Schrad. is found only occasionally. | 

On dry soils in open stands the jack pine frequently shows a 
tendency to form witches’-brooms. The terminal shoot, which is 
the part usually affected, develops into a thick-matted broom, pre- 
cluding any further growth in that direction. Trees thus infected 
usually show a rapid falling off in increment, probably dating from 
the time when the influence of the parasite was first felt. Another 
_ type of broom formation is confined to the lower and older branches 
and has a similar effect on the growth of the host. These brooms are 
probably caused by some perennial fungus. In the absence of any 
fruiting structures the causal organism can not be determined. 

The jack pine in its eastern range is not subject to mistletoe injury. 
Macoun ! reports the occurrence of Razowmofskya americana (Nutt.) 
Kuntze, the lodgepole-pine mistletoe, on the jack pine in Canada. 


1Macoun, John. Catalogue of Canadian Plants, pt. 3, p. 422. Montreal, 1886. 


8 BULLETIN 212, U. S. DEPARTMENT OF AGRICULTURE. 


The writer finds this mistletoe to be the cause of serious damage to 
the jack pine at its most western extension or where it approaches the 
zone of the lodgepole pine in the north. 


SAPROPHYTIC FUNGI. 


Aside from the previously mentioned wood-destroying species, 
which in many cases continue alive after the death of the host,! the 
usual strictly saprophytic fungi of coniferous woods are found on cut 
or fire-killed jack pine. Ceratostomella pilifera Fr., the blue-stain 
fungus, appears very rapidly after the death of the tree. In moist 
situations, species of Auricularia and Dacryomyces are surprisingly 
abundant, but can be of little importance, as the mycelium does not 
penetrate the wood to any appreciable distance. The first fungus 
of importance is Polystictus abietinus Dicks. This is a sap-rotting 
species and is seldom absent from fire-killed trees after the second or 
third year. Second in importance is Lenzites .sepiaria Fr., which 
works both in the sap and in the heartwood and usually appears on 
the fallen trunks after they have lain for three or four years, following 
up the first-mentioned fungus. The Lenzites appearing on jack pine 
is invariably the true, small, thin-fruited form, with radiating gills. 
Lenzites sepraria is as easily recognized by the orange-yellow color 
of its growing margin as the young, growing Polystictus abietinus is 
by its beautiful purple tinge. Homes pinicola Fr. has very little to 
do with the decay of fallen jack pine. This fungus has not been 
found to be very common. Polyporus palustris Berk. and Curt. 
occasionally appears, but is more common on dead Norway pine. 
Fomes carneus ‘‘Nees”’ very rarely occurs on jack pine. Lentinus 
lemdeus Fr., Polyporus sulphureus Fr., and Trametes sepvum have 
been collected by the writer on dead jack pine, but they are very 
rare. Resupinate Thelephoracee occur only in the moist stands of 
mixed species. Those which may be considered of importance in 
the decay of fire-killed timber in the forest are Corticowm byssinum 


= ee 


(Karst.) Burt., C. sulphureum Pers., C. galactinum (Fr.) Burt., | | 


Coniophora olivaceae (Fr.) Bres., and Peniophora globifera BE. and E. 
A yellowish white Poria which goes under the name of P. subacida 
Peck is occasionally found on fallen jack pine in Minnesota. This 
fungus has been observed by the writer in a fruiting condition on old 
boxes and barrel staves made from newly felled living trees. This 
indicates its probable parasitism on jack pine in the living forest. 


1 This is a fact that is not generally appreciated, and on it depends the solution of some very important 
pathological problems in the forest. Vigorously growing sporophores of 7'rametes pini springing from 
original infections in the living tree have been collected from a fallen western larch which had lain on the 
ground for moxe than 100 years. This was determined by the age ofa western red cedar growing astride the 
fallen trunk. Practically all the more serious wound and root fungi of the genera Trametes, Fomes, Poly- 
porus, and Agaricus in moist situations continue alive indefinitely after the death of their hosts. 


PATHOLOGY OF THE JACK PINE. 9 


INJURIES DUE TO OTHER CAUSES. 


In the absence of an adequate snow protection on the flat wind- 
swept pine barrens of the Lake States, winter injury sometimes 
results to young growth from long exposure to freezing temperatures. 
Winter-injured seedlings of jack pine, however, recover more rapidly 
than those of the more sensitive associate species and when in this 
condition are not so apt to be attacked by secondary deteriorating 
agents. It has already been stated that the deep root system of the 
jack pine is unfavorable to some root-destroying fungi. In like 
measure this is a safeguard against injury by wind. It is very 
unusual to find jack pine blown down by the wind when the trees 
are in a healthy condition. Very old trees sometimes succumb to 
strong winds, but it is found that such trees are usually mechanically 
weakened by wood-destroying fungi. The jack pine may be con- 
sidered very windfirm. Porcupines and squirrels are known to do 
considerable injury to jack pine during the winter months when food 
is scarce. The latter animal is much addicted to gnawing the galls of 
Peridermium cerebrum in the spring during the period of the exudation | 
from the diseased bark of a sweet yellow liquid which bears the conidi- 
ospores of the fungus. Since squirrels also gnaw the galls when the 
geclospores are mature, they may be considered a factor in the dis- 
tribution of this fungus. The bark of the galls is frequently com- 
pletely gnawed away, killing the infection. 

In general, the jack pine is very sensitive to fire, which usually 
causes the greatest injury in the typical dry sandy jack-pine plains. 
In many cases fire injury in jack pine results from repeated burn- 
ings, the tree having successfully withstood the first slight ground 
fires. Fires in the more typical jack-pine forests pass through very 
quickly, so that the thickened bark immediately at the base of the 
tree affords sufficient protection until it is burned off by succeeding 
fires, which frequently occur notwithstanding the meager ground 
cover. The fact that the species frequently grows in orchardlike 
stands or in isolated groups, more or less separated from one another 
by free areas, greatly lessens the damage of the fire spreading from 
one group to another. However, the low-spreading branches, which 
often extend to the ground, increase the danger from crown fires. 


CONCLUSIONS. 


With reference to the prevalence and severity of its fungous ene- 
mies, two distinct forest types for the jack pine may be recognized: 
The pure dry sandy-plain type and the mixed type of moist protected 
oils. 

_ The most important fungous disease of the jack pine is Peridermium 
cerebrum Peck, the control of which in many localities is quite a serious 


10 BULLETIN 212, U. S. DEPARTMENT OF AGRICULTURE. 


forest problem. The fungus attacks all age classes, causing the 
death or early suppression of trees of tender years and seriously 
interfering with the propagation and development of more mature © 
growth. | | 

From the standpoint of merchantability, wood-destroying fungi in- 
the living tree are in almost all regions a negligible quantity. The 
two most important are Trametes pin (Brot.) Fr. and Polyporus — 
schweinitzii Fr. These, however, do not produce any appreciable — 
decay till after the tree reaches its period of decline, which is attained 
after a comparatively rapid early growth. This period may be ~ 
placed approximately at from 60 to 80 years. : 

The wood of dead jack pine rapidly deteriorates under the influence 
of a number of saprophytic fungi and may not be expected to remain ~ 
sound in the forest for more than two or three years. 

Jack pine is sensitive to heat, but suffers only occasionally from 
winter injury. | . 

Because jack pine in general is comparatively free from a number ~ 
of the diseases which are common on other conifers and is resistant 
to drought, winter injury, and frost, it is admirably suited for refor- 
esting many of the dry sandy regions of the North-Central States. 


ADDITIONAL COPIES 
OF THIS PUBLICATION MAY BE PROCURED FROM 
THE SUPERINTENDENT OF DOCUMENTS 
GOVERNMENT PRINTING OFFICE 
WASHINGTON, D. C, 
AT 


5 CENTS PER COPY 
V 


WASHINGTON : GOVERNMENT PRINTING OFFICE ; 1915 — 


t 
4 


“S : ‘ 


East) 


¢ re = 
© 


“ 


. iw : ' ‘ 
; rr) i ee 
c ; 


Tint cy aA 
, 
ry ” 


oo 


‘ 
’ a4 
Wy 
> 
> 
4 
‘ 

' 

i? 

“, 
' 

it 


tes 5 Bday ; on . 
im Wiad, ytd) tt 
a. 


» eee | 
Meee aNath Me) hors. 


‘eee nat i 4 ~ | : 
(Olu ee Re py Ps Tito ie 


af 


vom 74, *' 


UNITED STATES DEPARTMENT OF AGRICULTURE 


Contribution from the Bureau of Plant Industry 
WM. A. TAYLOR, Chief 


Washington, D. C. _ PROFESSIONAL PAPER August 23, 1915. 


THE TOXICITY TO FUNGI OF VARIOUS OILS AND SALTS, 
PARTICULARLY THOSE USED IN WOOD PRESERVATION.' 


By C. J. Humpurey, Assistant Pathologist, and RutH M. Fiumine, Scientific Assist- 
; ant, Office of Investigations in Forest Pathology. 


CONTENTS. 

; Y Page. | Page. 
a es Ree 1 | Toxicity to fungi of the more important pre- 
er 2 Shr vativeso. bnm 5. 345. fees t oxete peak 5 duced 31 
Tests conducted at the Forest- Products MEOOAEY = cece tos then bpis ieee Foc opin cine ae 35 

SIMI etatee temas ns 2. -lecce ones td BID UBEtADAY ssolts cee otek tee eas sade cee eae nee 37 
INTRODUCTION. 


Within comparatively recent years the subject of wood preserva- 
tion has become of paramount importance, largely resulting from the 
economic conditions which necessitate the utilization of timber inferior 
in its resistance to decay to species formerly readily obtained. The 
rise of wood preservation in the United States within the last two 
decades has been very rapid. The principal preservatives used have 
consisted of coal-tar creosote and zinc chlorid, either alone or in 
combination. Such experimental work as has been done prior to the 
last two or three years has been directed in large part toward perfecting 
the mechanical processes of injecting the preservatives into wood, 
with an idea of securing the greatest relative efficiency as compared 
with the cost involved—purely an engineering proposition based on 


_ 1The writers wish to thank Mr. Howard F. Weiss, Director of the Forest-Products Laboratory, Madison, 

Wis., for the interest displayed and suggestions offered during the progress of this work, as well as for the 
laboratory facilities placed at their disposal. Thanks are also due to Mr. Ernest Bateman, Chemist in 
Forest Products at the Forest-Products Laboratory, for all the data on chemical analyses of the different 
preservatives, and to Drs. R. H. True, F. D. Heald, E. P. Meinecke, Caroline Rumbold, and Mr. W. H. 
song, of the Bureau of Plant Industry, for many helpful criticisms of the manuscript. The investiga- 
tions were conducted at the Forest-Products Laboratory, Madison, Wis., maintained by the Forest Service 
ofthe United States Department of Agriculture in cooperation with the University of Wisconsin. 


_ Notr.—This bulletin gives the results of a series of investigations conducted at the Forest-Products 
Laboratory, Madison, Wis., as to the preservative value of various oils and salts and their toxic effect on | 
wood-destroying fungi. . 
88340°—Bull. 227—15——1 


2 BULLETIN 227, U. S. DEPARTMENT OF AGRICULTURE. 


economic considerations as far as the preservatives used are con- — 
cerned. These preservatives have in a general way proved to be © 
fairly good, but recently further efforts have been made to supple- 
ment them, or perhaps to substitute for them under certain condi- © 
tions other substances which may be more applicable to certain 
requirements. | . . 
In addition to the toxicity of a preservative toward wood-destroy- — 
ing organisms, its value to the trade will depend largely upon its | 
varied physical and chemical properties, as well as upon certain | 
economic considerations involved. The present publication, how- — 
ever, deals only with the toxic properties. Considerable literature 4 
on the toxic effect upon plant and animal life of various chemical — 
substances, both inorganic and organic, has accumulated, but rela- — 
tively little work has been done with wood-destroying fungi, and any ~ 
attempt to draw analogies would be misleading. ) 
Even among fungi the toxic concentration of a given preservative — 
will vary, depending upon the organism, the concentration of the — 
preservative, and the growth conditions, such as the composition of 
media and the temperature. In order to call attention to the funda- — 
mental character of certain of these variations and to illustrate the — 
points involved, a brief survey of some of the work of other investi- — 
gators is here presented before the results of our own work are dis- © 
cussed. No attempt has been made to review all the literature on © 
this extensive topic, and only a few references which serve to illus- — 
trate the points the writers desire to emphasize are included. 


HISTORICAL. 


STIMULATION BY TOXIC SUBSTANCES. 


Many investigators have established the fact that certain sub- — 
stances that are poisonous in higher concentration exert only a stimu- — 
lating effect in extreme dilution. For many years the fluorin com- — 
pounds have been known to have this stimulating effect upon fer- — 
mentation. Ono (22)! and Raulin (24) have found similar favorable — 
influences exerted by lithium nitrate and sodium fluorid upon alge — 
and by mercuric chlorid and copper sulphate upon fungi. Fred (9), — 
in his studies on nitrogen fixation, denitrification, ammonification, — 
and putrefactive processes in soils, due to certain bacteria and yeasts, 
concludes that the yield is in proportion to the toxic stimuli. Like- — 
wise, Clark (3, p. 400), in his work on the toxic effect of many acids — 
and salts upon fungi, found that many deleterious agents which at — 
certain concentrations retard germination or early growth after- 
wards cause a great acceleration of mycelial development. 3 


1 Figures in parentheses refer to the bibliography at the end of this bulletin. 


THE TOXICITY TO FUNGI OF VARIOUS OILS AND SALTS. 3 


VARIATION IN TOXICITY OF CHEMICAL SUBSTANCES TO DIFFERENT FORMS OF PLANT 
LIFE. 


A review of the literature on the action of various toxic agents 
_ shows that the different forms of plant and animal life often behave 
very differently toward the same chemical substance. However, on 
account of the complexity of the digestive and absorptive processes 
‘in the higher animals, particularly man, a direct comparison of these 
forms with plant life is of little value, although the economic consid- 
eration of safety in the handling of substances in commercial use is 
of great importance. 

A few general statements to indicate in a concrete form the differ- 
ences in behavior between the larger plant groups, as well as indi- 
vidual species, will illustrate the point which it is desired to make. 
It is unfortunate that the work of different authors can not, in 
many instances, be directly compared, on account of differences 
in the method employed. However, much of value can be deduced 
from the few available examples. 

In his valuable work, Clark (3) calls clearly to the attention the 
variations among different species of molds. Certain toxic agents 
are shown to present great differences in this respect and others only 
slight ones. Even the stage of development of a single organism is 
of great importance, the conidia of the five species used proving more 
sensitive than the mycelium, so that the inhibition point for spore 
germination can not safely be considered as the toxic point for the 
development of mycelium. 

_ Other species of fungi, however, may behave differently from the 
ones Clark worked with, for Rumbold (25, p. 431) has recently shown 
that the ascospores and conidia of the blue-stain fungus (Ceratosto- 
mella sp.) are more resistant than the mycelium to sodium hydroxid 
and sodium carbonate. 

_ Another interesting phase of the question has been studied by 
Pulst (23). This investigator shows that the common green mold 
(Penicillium glauwcwm) has the power of gradually increasing its 
Tesistance to toxic agents. He claims that the individual itself 
without change of generation, but after a somewhat longer period of 
time, works up its resistance to copper sulphate to a high degree. 
He also shows by experiment that spores sown from generation to 
generation on progressively increasing concentrations of this salt 
likewise attain greatly increased resistance. Similarly, this newly 
developed resistance is evidenced by an increased rate of growth. 
For instance, when spores produced on a 3.2 per cent solution of 
copper sulphate are transferred to new media of like concentration, 
the mold will fruit again in about 10 days, while spores obtained from 
a culture containing no toxic substance and transferred in exactly 
the same manner require more than three months to reach the same 
stage of development. 


‘ga 
<< 


4 BULLETIN 227, U. S. DEPARTMENT OF AGRICULTURE. 


Seed plants.—A great amount of work has been done to ascertain 
the effect of various toxic substances on the roots of higher plants. 
A discussion of this work, however, is not essential to the present ~ 
paper beyond showing that a considerable difference exists between 
the behavior of this group of plants as ee with the lower — 
forms. 

In the comparison by Harvey (11) of his own work on an alga 
(Chlamydomonas multifilis) with that of True and Hunkel (30) on a_ 
flowering plant (Lupinus albus), both investigators using the ortho, 


meta, and para compounds of dihydric phenol, eresol, and phthalic | 
acid, the alga was found to withstand a concentration three to sro B | 


times as high as the flowering plant. 


Another striking illustration of this varied response to the same — 


toxic solution is recorded by Heald (12, p. 130), who found a fungus — 
vigorously growing on pea roots which had been killed by hydro- 
chloric acid. The average death fst for five species of molds 


studied by Clark (8, p. 306) Wasa5 ~3 HCl “24 per cent), while the — 
three species of puuuave plants ceatreeiba by Heald (12, p. 132) ~ 
succumbed at ——-~ 1600 a HCL or less. 


When copper sulphate was used, Kahlenberg and True (14) found — | 
that 0.00062 per cent was sufficient to kill the roots of Lupinus albus. 


After many experiments, Clark (3, p. 396) concludes that in the © 


case of mineral acids a concentration of 2 to 400 times the strength 
fatal to the higher plants is required to inhibit the germination of 
mold spores under favorable conditions. | 

Bacteria.—Although no direct comparison of bactericidal and 


fungicidal action is available, the experiments being usually per- — 


formed under somewhat different cultural conditions, the work of 
McClintic (17) on zine chlorid indicates a high resistance of certain 
bacterial organisms. . This investigator found that a 5 per cent — 
solution of zinc chlorid applied for one hour was not sufficient to kill 
Bacillus communis, while a 25 per cent solution required 10 minutes — 
to cause death. At this latter concentration 30 minutes was re- — 
quired to kill another bacterial organism (Staphylococcus pyogenes — 
aureus). | 
Spores of bacteria are well known to be very resistant to various 
agents. In the case of Bacillus subtilis, they are reported to have 
survived a 50 per cent solution of zinc chlorid for 40 days. | 
These figures are of interest when one recalls that a 3 to 6 per cent 
solution of this salt is the usual concentration employed in the — 
preservation of wood. q 
Yeasts.—Yeasts seem to behave toward many salts and acids 
very differently from seed plants and fungi. Bokorny (1) has re-— 


S| 


. 
ey 


> 


THE TOXICITY TO FUNGI OF VARIOUS OILS AND SALTS. 5 


cently reported the effect of about 50 different salts and acids upon 


yeasts, as compared with other organisms, and has found them gen- 
erally to be more resistant than alge or flowering plants. Silver 


nitrate, which is very deadly to many molds, bacteria, and alge (the 
bacterium Staphylococcus pyogenes requiring only 0.0002 per cent to 
_ check growth; the alge, Spirogyra and Cladophora, only 0.0001 per 


RR LDF FE. 


(A RN FT 


he 


A 


4 
a ait 


‘. 


cent), will not kill yeast until the concentration reaches 0.001 per 


cent. Similarly, mercuric chlorid is toxic to Spirogyra in a 0.000001 


yeast. 
Molds.—The common molds; such as Penicillium, Aspergillus, 
Sterigmatocystis, and others, taken as a whole, are highly resistant 


‘to toxic agents as compared with the true wood-destroying fungi. 


Whereas much experimental work has been done on the former, 
comparatively little has been carried out on the latter group. 

The so-called Peniciluum glaucum Link., which in the light of 
recent work has been shown to consist of a group of several distinct 
species of Penicillium, to which the composite name was indiscrimi- 
nately applied, is one of the most resistant molds recorded. Pulst 
(23), Clark (8), and Guéguen (10) all agree that from 16 to 21 per 
cent of copper sulphate is required to stop its growth, and Pulst 
claims that it will even germinate and fruit in a 33 per cent solution 
of this salt or a 38 per cent solution of zinc sulphate if allowed to 
develop a sufficiently long time, i. e., from three to five months. 

Clark (3) has tested the effect of some 28 salts and acids upon four 
or five of the common molds, the tests being made in hanging drop 
cultures of beet infusion. His table of toxicities indicates that such 
salts as mercuric chlorid, potassium bichromate, silver nitrate, and 
potassium chromate are approximately 400 times as effective against 
these organisms as copper sulphate, sulphuric acid, hydrochloric 
acid, and zinc sulphate, the comparison being based on molecular 
solutions. 

EFFECT OF COMPOSITION OF MEDIUM ON TOXICITY. 


The toxicity of a substance may vary for the same organism when 
culture media of different compositions are employed. This is due, 
in large part, to the chemical or physical affinity of some substances 
for certain constituents of the media, or possibly to some change in the 
permeability of the plant protoplasm. The well-known reaction 
of some copper salts with sugars and of mercuric chlorid with albumi- 
nous compounds, or the effect of adsorption will serve to illustrate 


the point. 


The most careful work on toxicity has been conducted, using pure 
distilled water as a medium. However, the use of this method with 
fungi is practically limited to the germination of spores; nutrient 


6 BULLETIN 227, U. S. DEPARTMENT OF AGRICULTURE. 


substances must be added if further growth is desired, and the addi- 
tion of each nutrient substance introduces a new factor of error. 
Unlike bacteria, which can be grown well in synthetic liquid media 
of known composition, wood-destroying fungi prefer a more complex — 
and solid medium for their satisfactory development. This latter, | 
as a rule, consists of a mixture of meat broth and sugars solidified | 
by agar-agar or gelatin. 2 
Various investigators have used different types of media and dif- — 
ferent methods, and this accounts in large part for the variability in 
results. Some, as Clark (3), have used simple plant decoctions, 


others bouillon, and still others a nutrient agar or gelatin modifiedin | 


various ways as to available carbon and nitrogen. | 
Le Renard (16), in his work on Penicillium crustaceum, shews that — 


toxicity is closely associated with the composition of the medium ~ 


and in the same medium varies somewhat with its concentration. 
Likewise the presence or absence of certain constituents may 
determine the temperature which an organism will endure on dif- 
ferent media, for Thiele (27) has shown that the maximum tempera- 
ture for the growth of Penicillium glaucum on grape sugar is 31° C.; | 
on salts of formic acid, 35° C.; and on glycerin, 36° C. a 
Hoffmann (13) states that in the caseof Merulius lachrymans a slight 
growth takes place even at 30° C. on certain liquid media, while on © 
solid media (5 per cent agar-agar) the fungus was killed at that tem- 
perature. He likewise thinks that as a fungus becomes accustomed ~ 
to a certain culture medium in its development it gradually over- — 
comes certain unfavorable conditions. 
So far as the writers are aware at the present time, the media most — 
satisfactory for the growth of wood-destroying fungi are not free 
from the objection of being complex, variable, and more or less — 
unknown in their chemical composition; however, certain synthetic — 
media are being developed in the course of the work which show ~ 


promise of being satisfactory. In an effort, however, tosecure results — 


comparable as far as possible with those of certain European investi- — 
gators, such as Malenkovié and various workers at Munich, and also 
Rumbold in this country, the malt-extract agar medium used by — 
these workers has been adopted. This medium will be described later. 


EFFECT OF ADSORPTION ON TOXICITY. 


The apparent diluting effect which inert, practically insoluble 
matter exerts on toxic substances has been often observed. For — 
instance, the injurious effect of poisons is not so noticeable when — 
seedling roots are placed in sand and watered with toxic solutions ~ 
of definite concentration as when grown directly in such solutions. — 
This phenomenon of the removal from solution of a part of the toxic 
substance by nearly insoluble material, such as glass, quartz, pottery, 


eta OP, 


THE TOXICITY TO FUNGI OF VARIOUS OILS AND SALTS. 7 


hemp and cotton fibers, and starch grains, comes under the general 

term “adsorption.”’ It is often explained as a direct physical 
affinity of the toxic chemical for the inert substance; that is, a con- 
- densation of the substance on the surface or in the interstices of the 
insoluble matter, or the formation of a solid solution of the two, but 
_ chemists and physicists are not at all in agreement in regard to these 
_ explanations. 


Among others, True and Gies (29) and True and Oglevee (31) 
worked upon this problem, using seedlings of Lupinus albus and a 


_ number of inorganic and organic compounds. As adsorbing agents 


such substances as sand, glass, filter paper, and paraffin were applied. 
With copper sulphate they found that at least twice the usual toxic 


concentration could be endured by the Lupinus roots when a suf- 
ficient quantity of the insoluble matter was added to the hypertoxic 


solution. In summarizing their work they remark: 


It appears in general that the presence of a considerable body of certain insoluble 
substances in solutions of strongly toxic compounds both organic and inorganic in 
their nature, be they electrolytes or not, tends to decrease the toxic activity of the 


‘solutions in question. On the whole this ameliorating action is more clearly marked 


in case the poisonous soJutions concerned are dilute solutions of strong poisons than 
when relatively concentrated solutions of weaker poisons are concerned. 

Fitch (8) conducted a series of experiments with sulphuric acid 
and copper sulphate, using pottery, glass, sand, and filter paper as _ 
the adsorbing agents and two common molds (Aspergillus niger and 
Pemecillium glaucum) as the test organisms. She established for fungi 
the same phenomena of dilution that a number of other workers had 


- found to hold for flowering plants. 


_ The diversity of results secured when toxic substances are tested 
on various media, particularly such as contain starch grains and 
similar materials in suspension, no doubt is explained, in part at least, 
on the basis of adsorption. ) } 


RELATION OF TEMPERATURE TO FUNGOUS GROWTH AND TOXICITY. 


It is well known that temperature exerts a vital influence on the 
growth and development of fungi. Not alone is the temperature 


q range which permits the growth of the organisms highly variable, 
_ but also the optimum temperature in many cases varies for the differ- 


ent species. ‘Thus, for nine species of wood-destroying fungi studied, 


_ Falck (5, 6) indicated a growth range lying between 3° and 44° C., 
_ with the corresponding optima between 18° and 35° C. For Meru- 
__ hus domesticus (= M. lachrymans in part) this optimum falls between 


18° and 22° C.1; for Coniophora cerebella, 22° to 26° C.; for Polyporus 


- wvaporarius spumaris, 26° C.; for Lenzites abietina, 29.5° C.; for 


1 Hoffmann (13) states that under certain conditions of culture this optimum may be raised so as to 


5 a fall between 18° and 26° C. 


i 
8 BULLETIN 227, U. S. DEPARTMENT OF AGRICULTURE. 
Lenzites sepraria, 28° to 32°°C.; and for Lenzites thermophila, 35° C. 


Below these temperatures growth becomes greatly lessened as the 
minimum is approached, while a rise of 4 to 8 degrees above the opti- 


mum often causes a total inhibition of growth or even death in the | 


case of very sensitive species. 

Different stages of the same fungus may also offer a different re- 
sistance to temperature changes, this being much less under moist than 
under dry conditions. For instance, Falck (7, p. 339) found that 
fresh fruit bodies of Merulius domesticus were killed in 30 minutes at 
40° to 42° C., and in 15 minutes at 46° C., while from 12 to 16 hours 
were required to kill dry spores at 42°. J 

As compared with this fungus, the same author shows that agar _ 
cultures of Lenzites sepiaria can survive more than three hours at _ 
60° C. q 

The resistance of a fungus to toxic substances is greatest under ~ 
temperature conditions most favorable to its development. After — 
conducting a series of tests on several molds to determine the germi- 
native capacity of the spores in varying concentrations of nitric and _ 
sulphuric acids and copper sulphate at different temperatures, either — 
directly in the solutions or after removal to nutrient media following 


immersion for 24 hours, Brooks (2) states that ‘‘in most cases the ~ 


deleterious action increased very rapidly with rise in temperature,” ~ 
but that ‘in all instances the injurious effects were least at the opti- — 
mum for the fungus.”’ 


RELATION OF LIGHT TO FUNGOUS GROWTH. 


Light also exerts an appreciable effect on the development of wood- — 


destroying fungi. This is evidenced in two ways: (1) By its influence © 
on the growth of the mycelium, and (2) by the réle it plays in the ~ 
production of normal fruiting bodies. In most instances at least, — 
partial illumination is essential to normal fruiting. The effect on the 
rate of growth of the mycelium, however, is less marked, but still quite 
appreciable. Of seven species of wood-destroying fungi studied, Hoff- 
mann (13) reports that growth in the dark was from 4.1 to 17.8 per — 
cent (average 9.9 per cent) better than in sunlight. In carrying his 
experiments still further and examining the effect of the red and blue © 
ends of the spectrum, respectively, he found that the former gave 2.6 — 
per cent better growth in the case of Pazillus acheruntius and 59.3 
per cent in the case of Polyporus vaporarwus (average for nine fungi 


14.6 per cent). 
WHAT DETERMINES TOXICITY ? 


An adequate discussion of the subject of what determines toxicity — 


would lead us into one of the most difficult fields of biological chem- _ 
istry and physiology, hence, for the purposes of this publication, the — 


writers omit reference to a great mass of literature covering the 


} THE TOXICITY TO FUNGI OF VARIOUS OILS AND SALTS. 9 


more involved aspects of the question and merely bring forward a 
few of the points which serve to illustrate certain phases. 

In the previous discussion it has been seen that the degree of 
toxicity manifested is relative and closely associated with the envi- 
- ronmental conditions and the particular physiological constitution 
_ of the individual organisms under consideration, as well as with the 
- concentration of the different toxic substances employed and the 
_ chemical and physical relations which these bear to the media upon 
which the organisms are grown. Why certain concentrations of 
_ substances are toxic to one plant and not to another, or why the same 
species varies in its tolerance to a certain toxic agent, is more or less 
obscure. According to Heald (12, p. 126) it may be a case of ‘‘ adapta- 
_ tion and adjustment,” and this is at least suggested by the work of 
_ Pulst (23) in increasing the resistance of Penicillium glaucum to cop- 
_ per sulphate. In support of his view Heald further states: 

Those substances which are poisonous to plants are generally such substances as are 
not accessible to plants in their normal habitats, at least to any extent, while those 


_ substances which are generally present in the soil have no injurious effect, or at least 
not in the same degree of concentration at: which we find them in the soil. 


However, for the purposes of the present paper the question of 
how the toxic substances exert their effect is not so near to the point 
as is the question of what particular components of the substances 
are the effective ones. On the basis of the separation of compounds 
into their constituent ions (elements or radicals) when brought into 
solution, many efforts have been made by comparison of different 
_ substances which have certain ions present in varying proportions to 
_ determine the most active part of the molecule. As many substances, 
_ particularly the more complex, do not become completely dissociated 
_ in solution, experimental work largely draws its inferences from the 
_ simpler compounds, mainly the inorganic. 

_ As a result of work on such ionized molecular solutions, investiga- 
_ tors quite generally agree that in case of the salts of heavy metals, 
like copper and mercury, it is the metallic ion that is largely effective. 
In the case of strong acids, such as hydrochloric and sulphuric, the 
hydrogen ion is said to be the principal toxic element. The work of 
_ Kahlenberg and True (14) proves the great activity of hydrogen and 
_ shows that in mixtures of such acids the toxicity is proportional to 
_ the number of free hydrogen ions present. 
- In 1900 True (28) published an account of the investigation of 20 
acids, both inorganic and organic, together with their sodium salts, 
in an effort to extend our knowledge of the effective toxic elements, 
_ the toxicity tests being conducted on the roots of Lupinus albus. 
_ With the simple inorganic acids, which readily dissociate in solution, 
he corroborated earlier views that the H ion gives the greater part of 
_ the toxicity to the solution, the corresponding sodium salts of the 
| 88340°—Bull. 227—15——2 


10 BULLETIN 227, U. S. DEPARTMENT OF AGRICULTURE. 


acids being only slightly toxic. With the organic acids, in which — 


lonic dissociation is usually less complete, he also found that the 
relative importance of the H ions in general varied with the per- 
centage of dissociation. If the dissociation was relatively slight, the 
nonionized molecule itself exerted the predominating influence. In 
general, the anions of organic acids were found to possess relatively 
slight toxic properties, oftentimes so slight as to be almost negligible, 
and, since both the sodium ions and the anions were usually but 
weakly toxic, it followed, as a rule, that sodium salts showed but 0.5 
to 3 per cent of the toxic value of the corresponding acids. Carboxyl 
hydrogen proved much more toxic than hydroxyl hydrogen. Since 
in the phenols this latter form of combination occurs, and since these 
substances do not ionize, the toxicity here must be referred entirely 
to the undissociated molecule. 

In order to throw further light on the behavior of phenols and their 
derivatives True and Hunkel (30) extended their investigations on 
Lupinus albus to this group. The results bear out their earlier con- 
clusions that electrolytic dissociation of phenylic bodies plays but a 
very subordinate réle in determining their toxicity. However, in a 
few instances, such as with picric and salicylic acids, the cresols, and 
the mononitrophenols, electrolytic dissociation is said to exert a pro- 


nounced influence. Some phenols also, like pyrocatechol and hydro- 


quinone, which are comparatively unstable, may quickly change to 
constituents even more fatal than H ions. Certain radicals seemed 
also to have specific properties when introduced into the molecule. 
For instance, the number of hydroxyl groups appeared to have little 
influence, while the introduction of the methyl group into the benzene 
nucleus increased the toxicity to a considerable but variable degree, 


as shown by the cresols and less plainly by orcinol; however, replacing 


the H of a hydroxyl group by a CH, group had little effect. The 
introduction of the isopropyl group into the cresols further increased 
their toxicity. The presence of one or more nitro groups likewise 
increased toxicity to a great degree, but the number of these groups 
seemed to make little difference. | 

Similarly, in the case of certain organic compounds (cf. 7, pp. 351- 
352), Ehrlich and Bechhold have shown that the introduction of — 
halogen and alkyl groups into the benzol ring increases the toxicity 
of phenols to diphtheria bacteria, two molecules of pentabrom- 
phenol being about equal to 40 molecules of trichlorphenol and 100 
molecules of phenol. On the other hand, the introduction of the car- 
boxyl group was said to lessen toxicity. 

Likewise, Falck (7, pp. 355, 357) states that nitrophenols and dini- 
trophenols are considerably more toxic than phenol and more so when 
the nitro groups are in the ortho position than when in the meta or 
para position. The most effective of 19 nitrophenols which he tested 


THE TOXICITY TO FUNGI OF VARIOUS OILS AND SALTS. Le 


ik in Petri dishes on agar against the fungus Coniophora cerebella were 


the sodium or potassium salts of dinitrophenol (C,H,-(NO,),[2.4] 
ONa) and dinitro-orthocresol (C,H, -CH, [2]. (NO,),0Na). 
Generalizations, however, are not alyaie applicable by analogy 


& and may serve only for certain limited groups. In his work on 


numerous fluorin salts Netzsch (21) found that the fluorin ion was 
_ the most active, the relative toxicity of the simpler and consequently 
more readily dissociated salts, at least, being in direct proportion to 
the amount of fluorin in the molecule. When the acid (HF) itself, 
however, was under consideration it was found to be even more toxic 
than its simple metallic salts, indicating the great activity of free 

hydrogen. 


TESTS OF THE TOXICITY OF WOOD PRESERVATIVES. 


It is only within the past decade that laboratory tests to determine 


the relative toxicity of substances adapted particularly to wood 


preservation have been undertaken. These lack the refinement of 
_ earlier work, as it was not the intention to enter into the question as 
_ to why and how a substance was toxic, but merely to determine how 
much of a given poisonous substance was necessary to inhibit the 
— growth of fungi, particularly the wood-rotting forms. The result is 
that different investigators have used different methods, different 
- culture media, different organisms, temperature conditions which 
were often not the optimum for the fungi concerned, and ofttimes 
also impure chemicals and composite oils, such as creosotes, that no 
other investigator is able to duplicate except from the same sample. 
The problem has been attacked in two ways: (1) By mixing the 
_ preservative under consideration with various types of culture solu- 
tions, usually solidified by the addition of agar-agar or gelatin, and 
inoculating with the organisms desired; and (2) by injecting the 
_ preservative into wood and exposing the blocks thus treated to the 
— action of wood-destroying fungi. 

Tests of this sort were first suggested by Malenkovié (18) in 1904. 
The results of his work were first published in an Austrian military 
journal and later (19) amplified and printed in book form. He lays 
no claim to refinement of work, so it is difficult to correlate his results 
with later ones, except in a general way. The larger part of his ex- 
periments were carried out by injecting the preservative into wood, 

but a few beaker tests were made according to the following plan: 
Five glass beakers were filled with 100 c. c. of 10 per cent gelatin or 2 per cent agar 
_ media, and to each was added a certain amount of the antiseptic, such as 0.5, 1, 1.5, 
and 2 grams. The media were then melted, thoroughly stirred, and allowed to cool. 
Then, without any previous sterilization, a trace of some mold (unknown to the experi- 


menter) was transferred to the surface of the media, and the cultures were set away in 
adark, damp place. After 14 days observations were made to determine whether the 


_ surface had become moldy. The concentration that prevented mold growth was 


_ recorded as the toxic point for the preservative in question. 


12 BULLETIN 227, U. S. DEPARTMENT OF AGRICULTURE. 


As has been shown in the preceding discussion, tests that are 
conducted under any other than pure-culture conditions are not 
directly comparable with each other, for the different organisms 
react in an entirely different way to the same chemical substance. 
Moreover, the use of molds which at most produce but slight effect 
upon wood gives no more than the roughest approximation as to how 
wood-destroying organisms would behave under similar conditions. 

In 1910 Netzsch (21) conducted an exhaustive series of experiments 
on the toxicity of fluor compounds. As these compounds have 
only recently entered into the field of wood preservation, and as many 
of them have proved to be toxic agents of high efficiency, his work is 
of great technical value. He carried out the work much as Malenko- 
vié and other investigators have done, both by mixing the substances 
in gelatin culture media and injecting them into wood, but his tests 
on culture media were carried out under sterile conditions in flasks, 
tests tubes, or Petri dishes, so that many of the objections to the work 
of Malenkovié were eliminated. Into the gelatin media were intro- 
duced varying proportions of equimolecular solutions of the fluorm — 
compounds. The culture vessels were then inoculated, using both 
Coniophora cerebella (a true wood destroyer) and the green mold, 
Penicillium glaucum, the former beg maintained for about four weeks 
in an incubator at 20° to 21° C. His results, showing the point of 
inhibition of growth, are presented on the basis of one gram molecule 
of the preservative to the number of liters of culture media necessary 
to secure the proper concentration. In the present paper this ratio 
has been changed to the percentage basis (weight of preservative in 
volume of media), in order to compare his results with those of other 
investigators. 

About this same time Seidenschnur (26), head che of the wood- 
preservation laboratory of the Riitgerswerke-Aktiengesellschaft, at 
Berlin (Charlottenburg), presented the results of a few tests upon 
the comparative toxicity of zine chlorid and tar oils. His experi- 
ments were conducted in test tubes contaming gelatin media mixed 
with varying proportions of the antiseptics. After the mixture was 
prepared, the tubes were sterilized for one-half hour at 80° C.1. The 
tubes were then slanted and inoculated with Penicillaum glaucum. 
The toxic point was not determined, but the relative efficiency of the 
two substances was compared in parallel cultures. 

During 1911, J. M. Weiss (33, 34), chemist in the technical labora- 
tories of the Bee Manufacturing Co., New York City, published 
the results of a number of experiments to test the relative antiseptic 
value of creosotes and other oils. The substances were mixed in 
agar media. The organisms used consisted of a bacterium (Bacillus 
subtilis), a yeast (Saccharomyces glutinis), and a species of Penicillium. 


1 This treatment, however, is usually considered insufficient to insure sterility. 


THE TOXICITY TO FUNGI OF VARIOUS OILS AND SALTS. 18 


An effort was made to handle them in pure culture under sterile 
conditions. The selection, however, of test organisms which play 
at most but a slight réle in the decay of timber is not to be recom- 
mended. As many factors of error as possible should be eliminated 
_ from such tests, for there are certain to be many remaining after all 
precautions are taken. 

During the same year Rumbold (25) carried out a series of tests with 
_ different wood preservatives, using agar media in Petri dishes as well 
as toasted bread. soaked in the antiseptics. In the case of the agar 
cultures, the media and preservative were mixed before sterilization. 
This procedure is known to lead to very erroneous results with cer- 
tain substances, such as zinc chlorid and copper sulphate. In all 
cases the preservative and media should be sterilized separately 
and heated no higher than is necessary during the mixing, in order 
to avoid as far as possible any chemical combination which tends 
to occur. The higher concentrations of the salts mentioned above 
cause a liquefaction of agar or gelatin media when sterilized together. 
_ One test conducted in our laboratory showed that zine chlorid at 0.6 
per cent concentration when sterilized after mixing allowed even 
_ more growth of Fomes annosus than 0.2 per cent when the two com- 
_ ponents were not sterilized together. Concentrations of the sterilized 

mixture below about 0.4 per cent appeared to be stimulative, giving 
a white, fluffy growth, which was more luxuriant than in the creamy 
check cultures and which grew up over the under side of the covers 
of the Petri dishes. 
The use of bread for culture media likewise is objectionable, for 
_ the starch therein contained possibly acts as a diluting agent, as 
already indicated in the discussion of the phenomena of adsorption. 
For instance, in comparing Rumbold’s tests of sodium carbonate on 
bread and on agar it is seen that considerably more of the preserva- 
tive is required to check the growth of the organisms when the for- 
mer medium is used. 
In 1912, Falck (7), and Dean and Downs (4), published the results 
- of work on various wood preservatives in agar media, using wood- 
_ rotting organisms. 
_ The former covered a wide range of possible preservatives (some 
60 or 70), including phenols and cresols and their derivatives, benzol 
_ derivatives, fluorin compounds, acids, alkalies, and inorganic metal- 
lic salts. The work appears to have been very carefully done and 
is an extremely valuable contribution to the subject. It is open to 
_ the objection, however, that the tests were of too short a duration. 
_ Dean and Downs report only a few tests on tar oils in a bean-agar 
medium, using the cosmopolitan wood-rotting fungus Polystictus 
_ versicolor. ‘These investigators introduced a method of preparing 
_ creosote emulsions with gum arabic, which was considered advanta- 


14 BULLETIN 227, U. S. DEPARTMENT OF AGRICULTURE. 


geous,' particularly with heavy oils. They also attempted to improve 
upon the usual method of inoculating the surface of the culture with 
the mycelium of the test organism by cutting a small block out of the 
medium, placing the transferred mycelium in the aperture, and then 
covering this with the portion of medium which was originally re- 
moved. They claimed this would give a more accurate indication 
of whether the fungus was really growing on the treated medium 
or only on the fragment of medium which must necessarily accom- 


pany the mycelium when it was transferred. This appears, how- _ 


ever, from work in our laboratory, to be a refinement of doubtful 
expediency, for it has often resulted that when fresh, actively grow- 
ing mycelium is placed in intimate contact with the poison it will be 
directly killed, while if it has the opportunity to recover its vigor to 
a certain extent after the disturbance in its growth equilibrium, due 
to cutting and removal from the original culture, it may eventually 
withstand concentrations which would otherwise be fatal. 

The more important results of these different investigators are 
presented in Table IV (pp: 31-34). 


TESTS CONDUCTED AT THE FOREST-PRODUCTS LABORATORY. 
SCOPE OF THE WORK. 


The experimental work in wood preservation at the Forest-Prod- 
ucts Laboratory includes a physical, chemical, and pathological 
examination of various substances which may have a possible value 
in the industry (32). Therefore, since toxicity is but one factor, 
conclusions regarding the service value of these substances should 
not be drawn without giving due consideration to other factors.” The 
pathological tests are made in Petri dishes, using agar media, or by 
injecting the preservatives into wood and exposing the wood to the 
action of wood-destroying organisms. Only the Petri-dish method 
is herein described. This method has the advantage of giving 
results from which at least tentative conclusions can be drawn in a 
relatively short time. Conversely, it is open to certain objections 
for which due allowance must be made in generalizations regarding 
the possible behavior of a preservative when placed under service 
conditions. However, in experimental work on the toxicity of dif- 


ferent chemical substances it is often very necessary to secure indi- 


catory results as soon as possible. In this way many substances 
may be eliminated which are not worthy of further trial. After a 
preservative has been shown to possess high toxic properties under 


1 From the purely physical side of preparing the preservatives so they can be more readily handled 
the gum-arabic emulsions have proved satisfactory to the writers, but the gum arabic apparently reduces 
the toxicity to such an extent as to forbid its use in comparative tests. This fact has been determined 
since this manuscript was prepared. 

2See U.S. Dept. of Agriculture Bulletin 145, ‘‘ Tests of wood preservatives.”’ 


; 
‘ 


. 
‘ 
} 
‘4 
.. 
; 
| 
| 
a 


THE TOXICITY TO FUNGI OF VARIOUS OILS AND SALTS. 15 


Petri-dish conditions, tests on its properties whea injected into 
wood should follow, under both laboratory and service conditions. 

Recently, an attempt has been made by a European investigator 
(20) to correlate Petri-dish results directly with service values- 
First, the preservatives were grouped as nearly as possible according 
to their permanence in wood. Then, knowing the average length 
of life of the treated timbers, the amount of preservative necessary 
to inject to give this life, and the toxic point of the substances as 
indicated by Petri-dish tests, a curve was plotted using the first fac- 
tor as the axis of ordinates and the ratio existing between the second 
two as the axis of abscissas. From this curve the investigator would 
predict the possible service value of any new preservative of like per- 
manence in wood merely from the known Petri-dish ratio by locating 
the point at which its ordinate intersects the standard curve. 

Such mathematical calculations are interesting, but must neces- 
sarily be very limited in their application, since such variables as 
the solubility and volatility of the preservatives, the nature of the 
timber treated, and the soil and weather conditions to which the 
treated wood is exposed must necessarily exert a great influence on 
the length of the life of the material. 

At the Forest-Products Laboratory, 2,400 Petri-dish tests have 
been made to date on 54 different substances; however, not all are 
sufficiently complete to be reported. These include a few water- 
soluble salts, but in the main they comprise various oils and tars. 
These preservatives have been for the most part submitted by 
American and European cooperators interested in having the sub- 
stances examined. 

The tests were conducted using two wood-destroying organisms, 
Fomes annosus Fr. and Fomes pinicola (Sw.) Fr., which have a wide 
American and European distribution and are very important in the 
decay of wood, particularly coniferous timber. The former is 
undoubtedly the most serious fungus of coniferous mine timbers 
in the United States. 

In general, the molds used by other investigators may be con- 
sidered more resistant than the true wood-destroying fungi, but 
the writers have considered it advisable to use only wood-destroy- 
_ ing forms, in order to eliminate any possibly erroneous inferences. 


METHODS OF TESTING TOXICITY. 


| The method of conducting the tests was in principle the same as 
_ that used by other investigators, merely involving the mixing of the 
__ various preservatives in definite proportions with media nutrient to 
fungi. However, an attempt was made to refine the methods as 
_ far as possible, so as to eliminate certain sources of error to which 
attention has already been called. 


16 BULLETIN 227, U. S. DEPARTMENT OF AGRICULTURE. 


A culture medium made according to the following formula was 
used: 


Extract of 1 pound Jean beef in distilled water................-- 1,000 c.c. 
Léfflund’s malt extract i. is2s06:3. 21 ee ie ee eee 25 grams. 
Agar-agarl ciccesi¢ wtisselansss- ays apes cages t ee ee ae 20 grams, 


(Carefully filtered, but reaction not adjusted; slightly acid.) 


This is the formula largely used by German investigators. It is a 
good medium for the development of fungi, but, like all other media 
of organic and often unknown composition, offers the objection 
of possible chemical reaction with certain preservatives. How- 
ever, such synthetic media as were experimented with proved very 
poor substrata for the development of the organisms. 

The above medium after melting was measured * into 50-c. c. glass 
bottles with carefully ground glass stoppers, usually 17 ¢. c. to a 
bottle, using a standardized 17-c. c. pipette or a 25-c. c. graduate. 
One check was usually prepared for each series of concentrations 
and to this was added sufficient distilled water to make 20 ce. c. 
The stoppers were then sealed in with a rubber-glycerin burette-cock 
erease and capped with a small piece of muslin. The bottles were 
clamped in specially constructed frames (Pl. I, fig. 1) and givena ~ 
sterilization of 25, 20, and 20 minutes, respectively, at 100° C. on © 
successive days. 7 

The handling of the preservatives involved slight mgdinaniisnes 
for individual cases, but in all instances concentrations are based 
on the actual ait of the preservatives in grams in 20 ¢. c. -agar- 
preservative mixture. 

With inorganic salts soluble in water solutions were prepared 
varying from 3 to 10 per cent concentration (grams in 100-c. ce. solu- 
tion), and these were used by measuring into 50-c. c. bottles, similar 
to those used for agar, the desired amount of solution, using either a — 
10-c. c. or a 25-c. c. standardized burette graduated in twentieths 
or tenths of a cubic centimeter, respectively. To each bottle was 
then added sufficient distilled water to make 3 c. c. In all cases 
concentrations were based on the weight of dry salt present. 

All other preservatives were weighed into the 50-c. c. bottles on an 
analytical balance, and enough distilled water was added to make 
3c. c. In the case of a few viscous oils, namely, coal-tar creosote, 
coal-tar creosote Fraction V, wood tar, and wood creosote, which do 
not readily emulsify with water, 5 to 334 per cent stock emulsions? 
were prepared, using equal amounts of gum arabic and preservative 
and diluting with distilled water to the desired concentration. These 
emulsions were then used in place of the crude preservatives. 

1 Tn all measurements of agar one-half c. c. excess was allowed to cover the amount adhering to the 


glass containers. 
2This method usually produced a quite permanent emulsion. 


Bul. 227, U. S. Dept. of Agriculture. RPEATEXI: 


Toxicity STUDIES: APPARATUS AND PETRI-DISH CULTURES. 


Fig. 1.—Frame for agar and preservative bottles during sterilization. Fic. 2.—Inoculation case, 
showing water bath on hot plate and other apparatus used. Fic. 3.—Petri-dish culture of 
Fomes annosus cut into squares ready for transferring to the test plates; platinum needle with 
flattened tip used in the operation. Fias. 4 to 9.—Petri-dish cultures of Fomes pinicola on 
different concentrations of coal-tar creosote, grade C, after 5 weeks: 4, Check; 5, on 0.075 per 
cent; 6, on 0.1 per cent; 7, on 0.125 per cent; 8, on 0.15 per cent; 9, on 0.175 per cent. 


Bul. 227, U. S. Dept. of Agriculture. PLATE Il. 


Toxicity STUDIES: PETRI-DISH CULTURES OF FOMES ANNOSUS AND FOMES PINICOLA.—]. 


Fics. 10 and 11.—F’. annosus on different concentrations of coal-tar creosote, Fraction I, after 5 
weeks: 10, 0n 0.275 per cent; 11, on 0.3 per cent. Fias. 12 and 13.—F. pinicola on different 
concentrations of coal-tar creosote, Fraction II, after 514 weeks: 12, On 0.125 per cent; 13, on 
0.15 per cent. Fics. 14 to 19.—/F. pinicola on different concentrations of coal tar creosote, 
Fraction IV, after 9 weeks: 14, Check; 15, on 0.025 per cent; 16, on 0.05 per cent; 17, on 0.075 
per cent; 18,on 0.1 per cent; 19, on 0.125 per cent. Fias. 20 to 23.—F. annosus on different 
concentrations of coal-tar creosote, Fraction V, after 7 weeks: 20, Check; 21, on 0.1 per cent; 
22, 0n 0.5 per cent; 23, on 1 percent. Fic. 24.—/. pinicola on 1 per cent concentration of coal- 
tar creosote, Fraction V, after 6 weeks. 


Bul. 227, U. S. Dept. of Agriculture. PLATE Ill. 


Toxicity STUDIES: PETRI-DISH CULTURES OF FOMES ANNOSUS AND FOMES PINICOLA.—I]. 


Fias. 25 and 26.—F’. pinicola on different concentrations of United Gas Improvement Co. 1.07 oil, 
No. 1101, after about 5 weeks: 25, On 20 per cent; 26, on 40 percent. Fics. 27 and 28.—/f’. anno- 
sus on different concentrations of water-gas tar distillate (sp. gr. 0.995 at 60° C.), after 6 weeks: 
27,On 0.2 per cent; 28, on 0.3 percent. Fic. 29.—F.annosus on 2.2 per cent concentration of 
S. P. F. carbolineum after about 6 weeks. Fic. 30.—/F. annosus on 0.15 per cent concentration 
of coal-tar creosote, Fraction III, after6 weeks. Fias. 31 to 35.—F. pinicola on different con- 
centrations of wood creosote (Douglas fir) after about 214 weeks: 31, Check; 32, on 0.05 per cent; 
33, on 0.1 per cent; 34, on 0.125 per cent; 35,0n 0.15 per cent. Fics. 36 and 37.—F. annosus on 
different concentrations of wood creosote (Douglas fir) after about 4 weeks: 36, On 0.2 per cent; 
37,0n 0.4 per cent. Fias. 38 and 39.—F. annosus on different concentrations of cresol calcium 
after about 6 weeks: 38, On 0.14 per cent; 39, on 0.28 per cent. 


Bul. 227, U. S. Dept. of Agriculture. PLATE IV. 


ToxiciTy STUDIES: PETRI-DISH CULTURES OF FOMES ANNOSUS AND FOMES PINICOLA.—III. 


Fias. 40 to 45.—F’. pinicola on different concentrations of wood tar (hardwood) after 2 weeks: 
40, Check; 41, on 0.2 per cent; 42, on 0.3 per cent; 43, on 0.4 per cent; 44, on 0.5 per cent; 45, on 
0.6 per cent. Fias. 46 to 48.—F’. annosus on different concentrations of wood tar (hardwood) 
after about 3 weeks: 46, On 0.1 per cent; 47, on 0.5 per cent; 48, check. Fics. 49 to 51.—F. 
annosus on different concentrations of copperized oil: 49, On 0.5 per cent after about 3 weeks: 
50, on 1.75 per cent after about 3 weeks; 51, on 36 per cent after about 514 weeks. Fic. 52.— 
F. pinicola on 50 per cent concentration of None-Such Special after about 3144weeks. Fias. 53 
and 54.—F. pinicola on different concentrations of zine chlorid (commercial) after 4 weeks: 
53, On 0.7 per cent; 54, on 0.75 per cent. 


THE TOXICITY TO FUNGI OF VARIOUS’ OILS AND SALTS. 1g 


In a few instances where the preservatives were low in toxic 
properties more than the specified 3 c. c. was necessary in order to 
secure the higher concentrations, and in these cases it became nec- 
essary to take into consideration the excess of preservative, and, 
considering it roughly as having the specific gravity of water, to 
reduce the agar by just this amount, in order that the combined vol- 
ume might not exceed 20 c. c. 

The concentrations to be used in the first series! of experiments on 
a given preservative were governed largely by the judgment of the 
investigator. The results thus obtained usually determined between 
what limits it was necessary to continue the work. The experiments 
were then carried on between these points, usually to within an accu- 
racy of about 10 per cent for the actual and total inhibition point 
_ for each preservative. Thus, if growth stopped at 0.5 per cent or 
below, the tests were carried to the nearest 0.05 per cent; if between 
0.5 and 1 per cent they were carried to the nearest 0.1 per cent, and 
so on up to the highest concentrations employed, usually 40 per cent, 
which would thus be tested to the nearest 4 per cent. This 40 per 
cent concentration is equivalent to an injection. of 24.9 pounds of 
the preservative per cubic foot, and it was thought unnecessary from 
a practical standpoint to go aon this point. 

After the proper quantities of preservative had been placed in 
50-c. c. glass-stoppered bottles, these were sealed and sterilized in 
exactly the sare way as the agar bottles and along with them. 

As a few experimental weighings before and after sterilization indi- 
cated that no loss occurred, even of such volatile substances as are 
contained in the lowest Sone of coal-tar creosote, the method 
may be considered safe. 

After sterilization, both the agar and preservative bottles were 
heated on the water bath, then transferred to a-sterile culture case 
(Pl. I, fig. 2), where the hot agar was poured into the preservative 
bottle and thoroughly mixed. In some cases one or two sterile glass 
_ beads were added to the preservative bottles to facilitate the mixing. 
These were removed later. 

The agar-preservative mixtures were then poured into sterile Petri 
dishes 100 mm. in diameter and 10 mm. deep. After cooling, each 
plate was inoculated at the center with a weft of mycelium 5 or 6 ° 
mm. square, cut from a Petri-dish culture (Pl. I, fig. 3) 2 to 3 weeks 
old of the fungus desired, either Fomes annosus Fr. or Fomes pinicola 
/(Sw.) Fr. The dishes thus prepared were then placed in an incu- 
bator and held at approximately 25° C. for periods varying from 4 
to 10 weeks, usually from 4 to 6. 


1 A series consists of a set of progressively increasing concentrations of a given preservative, tested at 
the same time against the action of a single fungus. 


88340°—Bull. 227—15——3 


18 BULLETIN 227, U. S. DEPARTMENT OF AGRICULTURE. 


In addition to the possibility, in some instances, of chemical 
combinations between the preservative and the media, there will also 
necessarily be a slight change in concentration, due to the drying 
out of the media when held in Petri dishes for six to eight weeks. 
Likewise, during this interval of time certain volatile constituents, 
particularly the lighter oils, may escape from the media. ‘ 

In recording observations of the behavior of the fungi toward the 
preservative, rapidity and amplitude of growth, together with any 
other peculiarities in appearance, were noted, inspection being made 
about once a weck. 

One very interesting feature of the tests was the development of 
a ‘‘halo” around cither the living or the dead transfers, or in advance 
of the fungous growth on the check cultures. These halos differed in 
appearance on the different preservatives, sometimes being lighter, 
sometimes darker, than the surrounding medium. In order to deter- 
mine whether the change was due to advance submerged hyphe, 
several transfcrs were made from the halos to fresh sterile agar, but 
as no living organisms were demonstrated by this test or by micro- 
scopical examination to be present it appears to be an advance 
physicochemical change in the media, arising, perhaps, from the dif- 
fusion of enzyms from the transfer, as Kellerman (15) has recently 
demonstrated for cytase produced in fungus cultures. | 


DEVELOPMENT OF FOMES ANNOSUS AND FOMES PINICOLA. 


IN NONTOXIC CHECK CULTURES, 


In the check cultures, Komes annosus produces a, rather compact 
creamy growth (PI. II, fig. 20, and Pl. IV, fig. 48), forming an abun- 
dance of the characteristic conidia described by Brefeld. F. pinicola 
(Pl. I, fig. 4; Pl. ITI, fig. 31; and Pl. IV, fig. 40), on the other hand, 
develops a fluffy, deep, white mycelium of considerably more rapid 
growth than F. annosus. At 25° C., F. pinicola develops a radial 
growth of 24 mm. in 9 days (average of 14 tests) and covers the plate 
in 15 days (15 tests); /. annosus develops 15 mm. in 83 days (19 
tests) and covers the plate in 204 days (12 tests). 


IN CULTURES CONTAINING TOXIC SUBSTANCES. 


The rate of growth of each of these two fungi on toxic media is — 


usually considerably retarded, in many cases strongly so, as com- 
pared with check cultures. In some instances where very low con- 
centrations of certain substances are used, a stimulating effect is ob- 
served, but this condition is reversed with increased concentrations. 
The stimulated growth on zinc-chlorid concentrations when heated 
in the presence of the culture media (such concentrations often being 
far above those necessary to kill when not so heated together) is 


THE TOXICITY TO FUNGI OF VARIOUS OILS AND SALTS. 19 


readily explained on the basis of chemical combination with the 
media. 

The length of time required to make an initial growth on different 
toxic media varies from a very few days up to seven weeks or more; 
check cultures usually start within two or three days. Table I 
illustrates this for a few preservatives. 


Tasie I.—Time required by Fomes annosus on 0.2 per cent concentrations and F. pinicola 
on 0.1 per cent concentrations to make initial growth from mycelium at 25° C. 


Preservative used. IF. annosus.| . pinicola. 
Davs. Days. 

TESS. yi Ene SSE tee 2to 3 2 to? 
ETM TaIN ee tee PNA Ted tek PSD esis. less. Rat Seok a 20 24 
a ESAT GS a al ae EI SE a a ea 18 21 
ES eee ee 15 18 
ME THCHION LIT... occ a ae ec a ee ae ele en ge es 40 $3 
eel oOSOemrITAC GION Vets ig) Fe seu ig Me We se dee oe oe eed NSS eee ede 53 


It is thus seen that no growth demonstrable to the naked eye on 
any of the concentrations mentioned occurred within a period of two 
weeks, and the error which would occur in discontinuing the tests 
at the end of 8 to 10 days, as several investigators have done, becomes 


very evident. 
RECORD OF TESTS CONDUCTED. 


A: description of each of the 18 preservatives used, accompanied 
by individual tables and notes showing the rate, amplitude, and 
appearance of growth on the different concentrations, as compared 
with the check cultures, is given on the following pages. Under the 
heading ‘‘Concentration of the preservative” in each table the average 
radial distance to which the fungus has grown from the margin of the 
transfer at the end of the test is indicated by numerals,! the position 
of the first zero marking the killing point: Thus, 4=30 to 40 mm.; 
3=20 to 30 mm.; 2=10 to 20 mm.; 1=1 to 10mm.; 0=no growth. 


Sodium fluorid. 


[Laboratory sample No. 1929. Purchased from Eimer & Amend, Chicago, Tll.] 


Times | Concentration of the preservative (per 
Tests. icing cent). 
Fungus. epee Sake 2 OLE, | i 
veri- 
Number.| Duration. | fied. | 0.05 | 0.1 | O15, |) 0.2) 71 0:25) | Cheek. 
| (aie a a al 
Weeks. Py 
Meponies aMMOSUS.2-:.-...-.-...... 9 4 1 4 a Z 1 0: | 4 
eeeniticola...................... ul 5 to7 aa amet | ig Dears i ee | 4 


1Ttshould be kept in mind that the growth rate designated as ‘‘4”’ is not necessarily the same on different 
preservatives or different concentrations of the same preservative. All cultures which have produced 
 agrowth ofat least 30 to 40 mm. radius at the end ofthe test are included. Some ofthese may have reached 
_ this point in two to three weeks, as in the case of the checks, while others may have required the full test 
period; hence, the data as presented show only the relative retarding effect of the higher concentrations. 

~ Tk 


20 BULLETIN 227, U. S. DEPARTMENT OF AGRICULTURE. 


Fomes annosus: In one week, the radial growth of the check was 15 mm.; 0.05 per 
cent, 20 mm.; 0.1 per cent, 15 mm.; 0.15 per cent, 3mm. In four weeks concentra- 
tions up to 0.15 per cent showed 20 to 30 mm.; 0.2 per cent, about2mm. Thus, the 
rate of growth on 0.05 and 0.1 per cent concentrations equaled or exceeded that of the 
checks, but the higher concentrations produced a decided inhibition. The growth 
on the toxic media appeared very much as on the check. 

Fomes pinicola: In two weeks, the radial growth of the check was 40 mm.; 0.05 per 
cent, 9mm.; 0.1 per cent, 4mm.; no growth on 0.15 percent. After four to six weeks, 
nogrowth on 0.15 percent. Thegrowth on the toxic media was fluffy, white, and quite 
similar in appearance to that on the check. 


Zine chlorid. 
(Pl. IV, figs. 53 and 54.) 


{Laboratory sample No. 2239. Cooperator, Grasselli Chemical Co., Cleveland, Ohio. Commercial salt, 
meeting the specifications of the American Railway Engineering and Maintenance-of-W ay Association. ] 


Tests. Times Concentration of the preservative (per cent). 
killing 
Fungus. point 
Num-] Dura- | veri- 


ber. | tion. fied. 0.1] 0.2 | 0.3 | 0.4 |0.45] 0.475 | 0.5| 0.6} 0.65 | 0.7 | 0.75 | Check. 


Weeks 
Fomes annosus. 33 | 5to8 1 a 1 if i Bel aa Leh Ot ao eee 4 


F. pinicola.....- 33 | 4to8 7a PP Ee el RAPE (SEI ieee) DR er eS 4 4 4 0 4 


Fomes annosus: In 18 days, the radial growth of the checks reached about 35 mm.; 
0.05 per cent, about equal to check; 0.15 per cent, 8 mm.; 0.3 percent, 1mm. There 
was usually no growth on higher concentrations until after about four weeks, and it 
was comparatively slight even after six to eight weeks, reaching only 1to8mm. The 
toxic cultures generally were denser and of brighter tan color than the check. 

Fomes pinicola: In two weeks, the radial growth of the check reached 40 mm.; 0.6 
and 0.7 percent, 10mm. After four weeks, 0.6 and 0.7 per cent reached 35mm. On 
the lower concentrations the growth was more fluffy than that on the check. 


Sapwood antiseptic. 


{Laboratory sample No. 1611. Cooperator, J. M. Long, Chicago, Ill. Formula (by weight, in water solu- 
tion): NaCl, 2.92 per cent; CaSOx, 0.246 per cent; ZnSOi+7 H20, 0.246 per cent; CuSO4+5 H20, 0.182 
per cent; FeSO.+4 H20, 0.0605 per cent.] 


Tests. Times Concentration of the preservative (per cent). 
__| killing 
Fungus. point 


Num-} Dura- | veri- x 
ber. | tion. | fied. | 16% | 2> | 30>) ) ets 


Fomes a@nnosus. con ccactecaoks bec ET eA Oto saat 4 4 = 2 2 1 ; 4 


Fomes annosus: In about three weeks the radial growth of check reached 40 mm.; x 


50 per cent, 10 to 15 mm.; 75 per cent, very slight growth. Penicillium developed 
abundantly on 100 per cent. The preservative up to 25 per cent concentration 
showed a decided stimulating effect. 

The first concentration is based on the solution, as given above, which was prepared 
and submitted by the cooperator. Above 163 per cent it was necessary to use a more 
concentrated solution, and a strength six times the original formula was prepared. 


THE TOXICITY TO FUNGI OF VARIOUS OILS AND SALTS. 21 


Coal-tar creosote, grade C. 


(Pl. I, figs. 5 to 9.) 


[Laboratory sample No. 1074. Purchased from the Creosote Supply Co., Chalmette, La. Liquid at room 
temperature, 8.4 per cent water; specific gravity, 1.0483 at 60° C.; flash point, 93° C.; burning point, 100° 
C.; 11 per cent distills below 205° C.; 54.1 per cent distills below 275° C.; 74.1 per cent distills below 320° C.] 


o0_: 4 
Tests. 5 & Concentration of the preservative (per cent). 
ie 
Fungus. if z 
Num-| Dura-} 22/2) 8/8 s 19 9 a1 
ber. | tion. | HO|/OCl|A{aAL A] N [ol] ote] ew] wo] oe] s 
SW Sy ee 4S) 0S Ne al Se lis Besa eral ar 
: Weeks. 
Homes ANNOSUS............-.- 44} 4to8 LI Re aes al Ballet |tns| deed | tel tet O 4 
RMMUMAN eo cas oes esse Zi ee COnGaleer nolan tecmber lms. OLS 2a. ce aiscee emt ee elas cre 4 


1 These values are based on gum-arabic emulsions. Later work; using the pure preservative, indicates 
that the toxic point may fall somewhat lower. ke 


' Fomes annosus: In 17 days the radial growth of the check reached about 40 mm. ; 
0.2 and 0.275 per cent showed initial growth only. In three to four weeks, 0.2 per 
cent showed 10 mm.; 0.25 to 0.5 per cent, 2 to3 mm. In six weeks, 0.525 per cent 
showed only initial growth. In seven weeks, 0.5 and 0.525 per cent reached 2 to 9 
mm. The growth on the toxic media was about the same in appearance as on the 
check. 

Fomes pinicola: In two weeks the radial growth of the check reached about 40 mm.; 
0.075 per cent, 3 mm.; no growth above this point. In four weeks, 0.075 per cent 
showed 25 mm.; 0.1 per cent, 13 mm.; 0.15 per cent,6 mm. After five weeks, 0.175 
and 0.2 per cent reached 3 mm.; above this point all growth was inhibited. The 
growth on the toxic media was dull white, with a crinkled edge. 


Coal-tar creosote, Fraction I. 


(Pl. IT, figs. 10 and 11.) 


(Laboratory sample No. 1094. Cooperator, Semet-Solvay Co., Ensley, Ala. Light liquid at room tem- 
perature; specific gravity, 0.934 at 60° C.; flash point, 62° C.; burning point, 69° C.; 78.3 per cent dis- 
tills below 215° C.] 


Concentration of the preservative (per 


Tests. cate cent). 
Fungus, sea a eit 
a verl- 
cheat ta fied. | 0.2 |0.225| 0.25 |0.275| 0.3. | Check. 
i Weeks. 
MIGIMGS ANMOSHS — 5. ee ele ee end 33 | 4to6 3 4 4 2 1 0 4 
4 


| 9 led A a a 13 | 4to6 1 4 De emt pn as [A 


_ Fomes annosus: In 10 to 14 days the radial growth of the check reached 20 mm.; 
0.2 to 0.25 per cent, from 1 to4mm. In four weeks, 0.2 to 0.225 per cent reached 30 
mm.; 0.25 to 0.275 per cent, from 7 to 10 mm.; no growth at 0.3 per cent. The toxic 
cultures produced a thin, stringy growth. 

Fomes pinicola: In two weeks the radial growth of the check reached 40 mm.; 
0.2 per cent, 1 mm. In four weeks, 0.2 per cent reached 40 mm.; no growth above 
this point. The toxic cultures produced a fluffy white growth, similar in appearance 
to that on the check. 


‘ 


22 BULLETIN 227, U. S. DEPARTMENT OF AGRICULTURE. 


Coal-tar creosote, Fraction IT. 


(Pl. II, figs. 12 and 13.) 


[Laboratory sample No. 1106. Cooperator, Semet-Solvay Co., Ensley, Ala. Naphthalene odor; nearly 
solid at room temperature; specific gravity, 1.003 at 60° C.; flash point, 79° C.; burning point, 85° C.; 
9 per cent distills below 205° C.; 95.9 per cent distills below 287° C.] ; 


Tests. Times | Concentration of the preservative (per cent). 
killing 
Fungus. z = point | 
um-| Dura- | veri- = ; 
ber. | tion. fied. 0.1 | 0.125; 0.15 |0.175 | 0.2 | 0.225 | Check. 
Weeks. 
Fomes aMNOsus. sce .cee 5 4--o-pe 20 | 5to9 1 fe 3 2 1 1 6 4 
1 PINIGOla Sas tons = sce ee eae 18 | 4to5 2 4 4 al amy [Ms S| op 4 


Fomes annosus: In two weeks the radial growth of the check reached 20 mm.; no 
growth on 0.15 per cent and above. In four weeks, no growth on 0.225 per cent. In 
six weeks, 0.15 per cent reached 12 mm.; 0.2 per cent, 6 mm.; no growth on 0.225 
per cent. The growth on the toxic media was compact and creamy in color. 

Fomes pinicola: In two weeks the radial growth of the check reached 40 mm.; no 
growth on 0.125 per cent. In four weeks 0.1 and 0.125 per cent reached 40 mm.; no 
growth above this point. The growth on the toxic media was a dingy white and less 
fluffy than that on the check. 


Coal-tar creosote, Fraction IIT. 
(Pl; 1H, fig. 30.) 


[Laboratory sample No.1107. Cooperator, Semet-Solvay Co., Ensley, Ala. Liquid atroom temperature; 
specific gravity, 1.045 at 60° C.; flash point, 103° C.; burning point, 110° C.; 0.9 per cent distills t elow 
215°C.; 4.7 per cent distills below 275° C.; fraction from 170° to 245° C. more or less solid with naphthalene. | 


Tests. Times Concentration of the preservative (per cent). 

Fungus. PA ar ear vj 

e Be S poin ed 
5 en Dae verified. 12 iS Ps a ea me a 3 
Sl[oO|lso 1 oS het eee 
Weeks. 

HOMES. ANMOSUSe.58 a. caeee cree toes 60 | 4to12 Pe tes ved ated een, 1) of -ebeae ae 4 
Fe ipinieota. 2224 Oe) Fy soe bes 1414 to7 1] 3). 2) 1) 504::3e eee 4 


1 The radial growth of Fomes annosus on concentrations above 0.2 per cent is very slight, usually not 
exceeding 1 mm., and the actual toxic point is difficult to locate. It lies between 0.25 and 0.35 per cent. 

Fomes annosus: In 19 days the radial growth of the check reached 40 mm.; 0.15 and - 
0.175 per cent, 1 or2mm. In five to six weeks 0.3 per cent showed 1 mm, and lower 
concentrations 1 to5 mm. The growth on the toxic media was creamy and slightly 
lighter than that on the check. 

Fomes pinicola: In two weeks the radial growth of the check reached 40mm. In 
about one month 0.05 per cent showed 3 mm.; 0.075 per cent, 2mm. In about seven 
weeks 0.1 per cent showed initial growth; lower concentrations from 16 to 23 mm. 
The growth on the toxic media was a fluffy white on the lower concentrations; denser 
on 0.1 per cent. . 


THE TOXICITY TO FUNGI OF VARIOUS OILS AND SALTS. 23 


Coal-tar creosote, Fraction IV. 


(Pl. II, figs. 14 to 19.) 


a " [Laboratory sample No. 1108. Cooperator, Semet-Solvay Co., Ensley, Ala. Liquid at room temperature; 
7 specific gravity, 1.088 at 60° C.; fiash point, 130° C.; . burning point, 136° C.; 0.9 per cent distills below 
_ _—«-245° C.; 54.3 per cent distills below 320° C. ] 


Tests. Concentration of the preservative (per cent). 


rie 
Fungus. 6 = 
aS Num-| Dura- | Pome |g to 12 _|4 
“per. | tion. YT™? S|SIS |All lala Sa ae 
S i=) oO >) oO S (==) re N oO oD iS) 

Weeks. 

Fomes annosus........-.--.. 75 | 5tol2 sa Fe Aes | [ee el - e 7 aa al La gs Le @ 4 
Semimicola.........-..-.--- 23 | 5 to 8 Pmt 2a loko | an ee (OF ERA SST ele ee oeee 4 


1 The growth of Fomes annosus on concentrations above 2 per cent is very slight, usually not exceeding 
imm. in six weeks, and the actual toxic point is difficult to locate. It lies between 2.5 and 3.5 per cent. 


__, Fomes annosus: In 12 days, the radial growth of the check reached 25 mm.; very 
slight growth on 0.2 to 0.5 per cent. In 18 days, 0.8 to 3 per cent reached 1 to 4 mm. 
In four weeks, 1.25 to 3 per cent reached 1 to5 mm. The growth on the toxic media 
was usually darker than on the check. 
j Fomes pinicola: In two weeks, the radial growth of the check reached 40 mm.; 
no growth on 0.025 per cent. In four weeks, 0.025 per cent showed 2 mm.; no growth 
on higher concentrations. In eight weeks, 0.025 per cent reached 25 mm.; 0.05 per 
cent, 15 mm.; 0.075 per cent, 10 mm.; 0.1 per cent, 2 mm.; no growth above this point. 
The growth on the toxic cultures was dull, compact, and crinkled. 


ij 


Coal-tar creosote, Fraction V. 


(Pl. I, figs. 21 to 24.) 


_ [Laboratory sample No. 1109. Cooperator, Semet-Solvay Co., Ensley, Ala. Heavy, tarry liquid; specific 
gravity, 1.150 at 60° C.; flash point, 172° C.; burning point, 178° G;; "10.1 per cent distills below 320° (O75 
63.3 per cent distills below 380° C. ] 


Tests. oa: Concentration of the preservative (per cent). 
Fungus. killing “xk 
Num-| Dura- | Point . ii 
arse er a verified. Onli Ob 1 7 7.8 8 30 | 331 | Check 
Weeks. | 
_ Fomes annosus......- 42) 4to9 0 “4 3 2 | i 1 1 0 4 
ee omrmcola.......-... 30 | 4to8 Li eat Sel hg a 2 1 OW deat ace oR Lewes, 4 


1 Those values are based on gum-srabie emulsions. 


_ Fomes annosus: In 10 to 14 days, the radial growth of the check reached about 
-40mm.;5.5 to 30 percentshowed1to4mm. In four weeks, 5.5 to7.5 per cent reached 
8 to 15 mm.; 15 and 25 per cent, 2 mm.; no growth on 20 per cent gum-arabic emulsion. 
- The powih on the toxic media was mead and creamy on the lower concentrations; 

+ oo at first on the higher concentrations. 

_ Fomes pinicola: In two weeks, the radial growth of the check reached 40 mm.; 
in three weeks, 1 to 2 per cent showed initial growth; in four weeks, 3 to 6.5 per cont 
_ showed first growth; after eight weeks, 4.5 to 5 per cent reached 10 to 20 mm. The 
growth on the lower concentrations of the toxic media was white and fluffy; on the 
higher concentrations it was tawny and radiate, with a crinkled edge. 


24 BULLETIN 227, U. S. DEPARTMENT OF AGRICULTURE. 


Avenarius carbolineum. 


[Laboratory sample No. 1843. Cooperator, Carbolineum Wood Preserving Co., Milwaukee, Wis. Thick 
liquid at room temperature; specific gravity, 1.126 at 16.5° C.; flash point, 139° C.; burning point, 166° C.; 
1.1 per cent distills below 215° C.; 6.1 per cent distills below 275° C.; 1.91 per cent tar acids.] 


Tests. | : Concentration of the preservativ2 (per cent). 
Times 
Fungus. Tee ; 
Num-| Dura- | P° a 

Gar iio verified.| 0.175 | 0.275 |0.3/0.8) 1 | 4 | 5 | 5.25 | Check, 

Weeks 5 
FOmeS SMNOSUS we ob bee eee 53 | 4 to 10 ye er a I ee 2.2) 41) ae 0 4 
Pespinicolan: geass eae. Senseo 18 | 5to 6 2 Bf 1 O: |. cilees So] eee 4 


Fomes annosus: In 18 days, the radial growth of the check reached nearly 40 mm.;} 
0.3 per cent, 17 mm.; higher concentrations up to 4 per cent showed 1 to6mm. In 
four to six weeks, 5 per cent reached 1 mm. The growth on the toxic media was 
similar in appearance to that on the check. 

Fomes pinicola: In two weeks the radial growth of the check reached 40 mm.; 0.175 
per cent showed no growth. In four weeks, 0.175 to 0.275 per cent reached 1 mm. 
The growth on the toxic media was compact and darker than that on the check. 


S. P. F. carbolineum. 
(Pl. III, fig. 29.) 


{Laboratory sample No. 1844.. Cooperator, Bruno-Grosche & Co., New York, N.Y. Thick brown liquid, 
specific gravity, 1.127 at 16° C.; flash poimt, 133° C.; burning point, 157° C.; less than 9 per cent distills 
below 245° C.; about 30 per cent distills below 320° C.; 2.42 per cent tar acids. ] 


Tests. : Concentration of the preservative (per cent). 
Times 
Fungus. ponte g 
Num| Dura- | P° 
eral! Gian verified.| 1 1.5 |.1.75 | 2. | S04 4 aoe Check, 
Weeks. d 
Fomes antiosus! 5 7-tiee eee eee 73 | 5to8 Dalek 1 i 1 1A ee | 0 4 


1 The growth of Fomes annosus on concentrations above 3 per cent is very slight, usually not exceeding 

1 mm. in six weeks, and the actual toxic point is difficult to locate. [t lies between 4 and 5 per cent. 
Fomes annosus: In four weeks the radial growth of the check reached about 40 mm.; 
1 and 1.5 per cent, 1 mm. In six weeks, 1 and 1.5 per cent showed 5 mm.; 1.75 to 
4 per cent, 1 to5 mm. Tests were not made on concentrations below 1 per cent. 
The growth on the toxic media was quite similar in appearance to that on the check. 


Water-gas tar distillate. 
(Pl. III, figs. 27 and 28.) 


{Laboratory sample No. 2235. Cooperator, United Gas Improvement Co., Philadelphia, Pa. Greenish 
brown liquid; specifie gravity, 0.995 at 60° C.; flash point, 81° C.; burning point, 93° C.; 3.3 per cent 
distills below 180° C.; 61.7 per cent distills below 275° €.; 80.3 per cent distills below 320° C.] 


Tests. a Concentration of the preservative (per cent). 
Times 
Num-| Dura- | Ettea,| 0.1 |0.2/ 0.3/ 0.35 | 0.4 [9.45 65 | Check. 
ber. | tion, |VeTified.| 0.1 | 0.2} 0.3 | 0.35 | 0.4 |9.45] 0.5 | 0.6| 0. eck. 
Weeks. 


Fomes annosus........------ 58 | 5to8 02h ee a) 2°.) ee 4 


THE TOXICITY TO FUNGI OF VARIOUS OILS AND SALTS. 25 


_ Fomes annosus: In 12 days the radial growth of the check reached 15 mm.; 0.1 per 
cent, 2mm. In three weeks, 0.1 per cent showed about 20 mm.; 0.2 per cent, 5 mm. 
sg In six weeks, 0.2 per cent reached 17 mm.; 9.25 per cent, 15 mm.; 0.3 per cent, 5 mm.; 
0.35 to 0.6 per cent, from 1tol2mm. The growth on the toxic media was of a brighter 
creamy appearance than that on the check. 


United Gas Improvement Co. 1.07 oil (water-gas tar distillate). 
(Pl. ITT, figs. 25 and 26.) 


{Laboratory sample No. 1101. Cooperator, United Gas Improvement Co., Philadelphia, Pa. Mobile, oily 
liquid, with kerosene odor; specific gravity, 1.058 at 60° C.; flash point, 48° C.; burning point, 65°C.; 9.04 
per cent distills below 205° C.; 24.24 per cent distills below 315° C.; 67.9 per cent distills below 378° C.] 


Tests, Concentration of the preservative (per cent). 


Times 
Rees Seine 
Fungus. point : 
Num-| Dura- | veri- ; 3 
ber. | tion. | fied. | 4 re Gi a en ee eee ee 
Slmlaolololoja|Al|al]alo 
Weeks. : 
ames SMNOSUS:....-..-........ 2 ae Se cee: oe ee eee Va eee Wa a as | 4 
Smticwie 22) otis ile. 22) SED. feos 2.012. 5 Ab oi? Sh ae 2h 2 Oe a RR AE | 4 


Fomes annosus: In 10 to 14 days, the radial growth of the check reached 28 mm.; 
40 and 50 per cent, 2mm. In four to six weeks, 40 and 50 per cent showed nearly 10 
mm. The growth on the toxic media appeared denser and of a brighter tan color than 
that on the check. 

Fomes pinicola: In two weeks, the radial growth of the check reached almost 40 
mm.; 3 to 29 per cent, 2to 7mm. In four to five weeks all concentrations between 
3 and 40 per cent showed 2 to 15 mm. The growth on the toxic media appeared 
velvety, compact, and creamy, while that on the check was a fluffy white. 


Wood tar (hardwood). 
(Pl. IV, figs. 41-47.) 


_ [Laboratory sample No. 1561. Cooperator, Marden, Orth & Hastings, Chicago, Ill. Black, viscous liquid, 
with pyroligneous odor; specific gravity, 1.195 at 60°C.; flash point, 90°C.; contains 24 per cent water; 11.7 
per cent distills below 105° C.; 50.9 per cent distills below 244° C.; decomposition occurs above 230°.] 


Tests. Times Concentration of the preservative (per cent). 
: killing 
Fungus. e = point 
um-) Dura- | veri- " 
per. | tion. | fied, | 92 | 95 | 9-7 | 0.75 | 0.9 | 1 | 1.251| Check. 
' Weeks 
' Fomes annosus..............- 50 | 4to6.. Oy} 23a ae 4 4| 2 0 4 
EP MMICOME «wre co s-42--s------ 30 | 4to5.. 1 a a 4 Le Sea fs ees Pe 4 


1 Based on gum-arabic emulsions. 


_ Fomes annosus: In 9 to 10 days, the radial growth of the check reached 12 mm.; 
0.5 to 0.8 per cent, 1 to2 mm. In two to four weeks the check reached 40 mm. and 
concentrations up to 1 per cent showed 10 to 35mm. The growth on the toxic media 
_ was dark creamy and somewhat denser than that on the check. 

_ Fomes pinicola: In two weeks the radial growth of the check reached 40 mm.; 0.5 per 
_ cent,10mm.; nogrowthabovethis. In four to five weeks 0.2 to 0.7 per cent showed 40 
- mm.;0.725 per cent, 10 mm.; no growth on higher concentrations. The growth on the 
_ toxic media was luxuriant, white, and fluffy. 


26 BULLETIN 227, U. S. DEPARTMENT OF AGRICULTURE. 


Wood creosote (Douglas fir). 
(Pl. III, figs. 32-37.) 


[Laboratory sample No. 1099. Cooperator, Logged-Off Land Utilization Co., Seattle, Wash. Black 

liquid, with a strong pyroligneous odor; Specific gravity, 1.052 at 60° C.; flash Point, 45° C.; burning 

oe ‘85° es raericas 8.35 per cent water; 7.55 per cent distills below 100° C.; 54. 69 per cent distills 
elow 245° 


Tests. Times Concentration of the preservative (per cent). 


Num-| Dura- | veri- 
ber. | tion. fied. 0.1 | 0.125 | 0.15 | 0.2 | 0.25 | 0.4 | 0.45 | 0.6 | 0.651] Check. 


Weeks. 
Fomes annosus... 55 | 4to7 0 ye ene, 3 3 2: 2 1 1 0 ‘4 3 
“F. pinicola........ 26 | 4to6 0 4 4 4 | ee ee 4 


1 These values are based on gum-arabic emulsions. 


Fomes annosus: In 11 days the radial growth of the check reached 25 mm.; 0.15 to 
0.30 per cent reached 3 to6 mm. In 15 days, 0.1 per cent showed 30 mm. In four 
weeks, 0.15 to 0.30 per cent reached 18 to28 mm. Usually, from four to six weeks 
were required for initial growth on 0.6 to 0.625 per cent. The growth on the toxic 
media was dense, dark creamy, occasionally zonate. 

Fomes pinicola: In eight days the radial growth of the check reached 15 mm.; 
0.025 to 0.075 per cent, 11 to 20 mm. In three weeks, 0.025 to 0.1 per cent covered 
the plates; 0.125 per cent reached 17 mm.; 0.15 per cent 4 mm. In 34 days the 
initial growth appeared on 0.175 per cent. The growth on the toxic media up to 
0.125 per cent was white and luxuriant, exceeding that on the check. 


Cresol calcium. 
(Pl. III, figs. 38 and 39.) 


[Laboratory sample No. 2086. Cooperator, Blagden, Waugh & Co., London, England.] 


Concentration of the 


Tests. a ilies preservative (per cent). 
Fungus. point |-————--———— 
Number. |Duration.| Verified. | 9.14 | 0.28 | Check. 

Weeks. 


Homies anrigsus: = =... een ae eee eee | 8 4to7 1 4 0 4 


Fomes annosus: In about two weeks the radial growth of the check reached 20 mm.; 
0.14 per cent,3 mm. After three weeks the check showed 30 mm.; 0.14 per cent, 11 
mm. After six weeks, 0.14 per cent reached 30 mm.; no growth on 0.28 per cent. 
The growth on the toxic media occurred in alternating light and dark zones. 

A diversion from the usual method of weighing the preservative was necessary 
with this substance, since on sterilizing at 100° C. the preservative would form a hard 
crust on the sides of the bottles. To obviate this difficulty, the average weight of a 
drop from a small pipette was obtained (four tests). This was found to be 28 milli- 
grams, the drops varying not over 2 or 3 milligrams. The preservative was then added 
directly to the media bottles in quantities of one, two, three, or four drops, the killing 
point lying between one and two drops, which corresponds to 0.14 and 0.28 per cent, 
respectively. 


THE TOXICITY TO FUNGI OF VARIOUS OILS AND SALTS. 27 


Copperized oil. 
(Pl. IV, figs. 49 to 51.) 


{Laboratory sample No. 1095. Cooperator, Ellis-Foster Co., New York,N.Y. Probably acrude petroleum 
containing a slight amount of copper and sufficient vegetable oil to form a homogeneous solution; specific 
gravity, 0.937 at 25° C.; flash point, 125° C.; burning point, 164° C.; less than 0.2 per cent distills below 
215° C5 cide per cent distills below 320° C.; about 80 per cent distills below 360° C.; copper content, 0.34 
per cent. 


Tests. ‘ Concentration of the preservative 
Times (per cent). 

F killing 
ungus. int ta eS ea ee een 

Nunt '| puration,| verised 
ber eee ver 2) 51 | 301 33 | 86 |. 40°] Cherk. 

Weeks 

GMCS AMTOSUS: W< A2lss2.o-~\see se ~- 40 4to9 GAS A le Slee Oia yh G 4 
5 OOO ee eee 25 4to6 eran A diallers este 4 4 


Fomes annosus: In 18 to 22 days the radial growth of the check reached 40 mm.; 
the toxic concentrations up to 6.25 per cent showed the same growth, except that 
the check was denser. In about three weeks 15 to 30 per cent reached 1 to 11 mm. 
In nine weeks, 30, 33, and 36 per cent showed 12 to20mm. On the less toxic media 
alternating zones of lighter superficial growth and darker submerged growth occurred. 
On the high concentrations either a black submerged growth or a light-brown super- 
ficial growth appeared. 

Fomes pinicola: In two weeks the radial growth of the check reached 40 mm.; 
15 to 26 per cent, 20 to 27 mm.; 40 per cent, 2mm. In six weeks all concentrations 
up to 40 per cent reached about 40 mm. The growth on the toxic media was fluffy, 
but darker than that on the check. 


None-Such Special. 


(Pl. IV, fig. 52.) 


[Laboratory sample No. 2696. Cooperator, George M. Saums Co., Trenton, N. J. Yellow, oily liquid 
with strong varnish or paint odor; claimed by the manufacturers to waterproof and give a hard finish 
to timber, as well as prevent or stop decay; chemical composition unknown to us.] 


Tests. : Concentration of the preservative (per cent). 
Times 
killing 
Fungus. Beas point 
ber. |Duration.| verified. | 1 | 5 | 15 | 25 | 30 | 35 | 40 | 45 | Check. 
Weeks 
iGiMieS aMnNOSUS....>-207.2..---- 28 Are eee eee AS AM ASAE Ar pera Aes & 4 


OC 2 a 29 SOWA! ae Le. oe 4/ 4} 4] 4] 4] 4] 4].... 4 


_- Fomes annosus: In 10 to 14 days the radial growth of the check reached 20 mm.; 
concentrations from 5 to 45 per cent showed approximately 40 mm. The preservative 
appears to exert a nutritive or stimulative effect, rather than any toxic action, although 
the fungus will not grow on the pure preservative. The growth on the treated media is 
dark and submerged, rising to the surface later to form a very dense creamy mycelium. 
Fomes pinicola: In eight days the radial growth of the check reached about 30 mm.; 
0.25 to 3 per cent, 15 to 20mm. In two to three weeks 35 to 50 per cent showed 20 
to40 mm. The growth on all concentrations up to 50 per cent almost equaled that 
on the check. 


DISCUSSION OF TESTS. 


Table IT gives the results of investigations in our laboratory in 
_the use of such preservatives as have been sufficiently checked to 
- permit statements regarding their toxicity to the fungi noted under 


28 BULLETIN 227, U. S. DEPARTMENT OF AGRICULTURE. 


the test conditions outlined. In this table the preservatives are 
arranged in the order of their toxicity, beginning with the most 
toxic. . 


TaBLe II.—Killing point of Fomes annosus and F. pinicola for the various preserva- 
tives, compared with coal-tar creosote, No. 1074, and zinc chlorid, No. 2239. 


[Results marked with an asterisk (*) were not checked in duplicate, but they are approximately correct.] 


Killing point. 


zine 
Pounds | creosote. chlorid. 


Per cent. a cubic 


Fungus and preservative. 


—_—_R mm fe fn fs 


Fomes annosus (creosote killing point, 0.55 per cent; zinc- 
chlorid killing point, 0.5 per cent): 


Coal-tar creosote, Fraction Us..5...<sssstenuecducecan yon 0. 225 0.140] 2.5 282 
Sodrawml Muorid.. . RSs o 0k Sake ab kaki Wisdemab ies eee eee . 25 .156 | 2.2 2 
Crespo teglctaay. 2 een eke hac sen tone eens oe 0.14-.28 | 0.087-.175 | 3.9-1.9]| 3.61.8 
Coal-tar creosote, Fraction I.........- EI eC ee ete .30 1871 ae ¥.7 
Coal-tar creosote, Fraction ILL. .: cc. sé adits coy) Sew ameye *, 325 203 | 1.7 1.5 
Lie CHIOTIG: | 32045 3p toe eaten ie ean aa ee ee -50 -312] 1.1 Kr 
Coal-tar creosote, prdde C,... 020i dd. i. Wh eae 55 .3843 | 1 91 
Water-gas tar distillate No. 2235 (specific gravity 0.995)... *, 65 - 405 . 84 76 
Wood:ereosote’ (Douglas fir) uPA lo. Se eee et nea *, 65 - 405 . 84 FG 
W 00d bar (hardwOO0d ures ce tonnes bores cbice. Sewemets ¥1,25 .78 . 44 - 40 
Coal-tar creosote, Fraction TV .... 25. f7s.t0 sce pe etmankeeee *3.30 2.06 .16 Bp 
6. PF carbolinenm 6. a x sarc tania ce Seacoast 4.5 2.8 .12 11 
Avonarius carbolineum:.... ...242%.2 56hs eek oon depeiecan aun 5. 25 3.27 104 . 095 
Coal-tar creosote, Fraction. Vi .22-5..25%25 Jc ocap eee sees *33 20. 59 By La 015 
COPD OTEOG OL) a wicca nid aisle ois a ote on nates los Aopnee epee 40 25 -014 013 
United Gas Improvement Co. 1.07 oil, No. 1101........... 40+ 25+ -014— -013— 
None-Such Special (£24. Mck lost eta scnks Sek = sad bie 40+ 25+ -014— | .012— 
HAP WOO AMLIMONUG. =. 0. cue nsattnase ae pep mee meen re ee (ie ee See so -007— . 007 
Fomes pinicola (creosote killing point, 0.225 per cent; zinc- 
chlorid killing point, 0.75 per cent): 
Coal-tar creosote, Fraction 117 ...: /....iecunce vs Geuewenteee -125 -078| 1.8 6 
Coal-tar creosote, Frsetion LV o...c5scanacee ena cee seee sae #, 125 .078 | 1.8 6 
Coal-tar creosote, Fraction TI... ..0cseeteten cane usees ae 15 094} 1.5 5 
Sodium fluonid. 00>: 15-2 socnccdemeck reese eeue neem ae 15 094} 1.5 5 
Wood :creosote,( Douglas fir)... o5.5<)sSescceee rae eceuacteee *, 20 e125) fhshe 3.8 
Coal-tar creosote, Fraction 10. 52. i0> 2.0 penne eee . 225 -140] 1 3.3 
Coal-tar’creoseté, erade' Ces... eee ce sees eee =e nee ee . 225 140] 1 Soo 
Avenarius carbolineum.....-...-..-..2+s-2ssssssees sees. 30 . 187 75 2.5 
Zine chiorid, -sor.sosescschewsseweces sere eo eee eee 75 - 468 30 1 
Wiood tan (hardwood)s.c sss. -nee oop eee see eee 75 . 468 30 1 
Coal-tar creosote, Fraction 'V ....... 05.53 cancpiet okies *7.8 4. 87 . 029 - 096 
Copperized:oil7c1..~simanaceriopice ocaeeee Soee a eee 40+ 25+ .0056—| .019— 
United Gas Improvement Co. 1.07 oil, No. 1101........... 40+ 25+ -0056—| .019-— 
None-Such Special...... Ee ee eerie oe Ok Uy 50+ 31.2+ .0045—| .0015— 


1 Killing point lies between the limits given (1 and 2 drops of the preservative in 20 c. c. of the medium). 


Table II shows that of the 18 preservatives tested against Fomes 
annosus 6 totally inhibit growth at or below 0.5 per cent, 5 between 
0.5 and 3.5 per cent, 1 at 4.5 per cent, 1 at 5.25 per cent, and the 
remaining 5 show extremely low toxic properties, requiring from 33 
to 75 per cent. 

Sodium fluorid is particularly toxic, being slightly more than twice 
as effective as zinc chlorid. 

Cresol calcium in these tests shows a high toxicity, and the poor 
results reported against it in service tests’ are apparently due to a 
change in chemical constitution or to leaching, which did not take 
place under our method of testing. | 


1Unpublished report, Forest-Products Laboratory. 


THE TOXICITY TO FUNGI OF VARIOUS OILS AND SALTS. 29 


The three lower boiling fractions of coal-tar creosote are highly 
toxic, exceeding the creosote itself. Fraction IV is only about one- 
sixth as toxic as creosote. Fraction V, consisting of the last heavy 
residues, of which only 10 per cent distills below 320° C., is extremely 
__ low in toxicity, with a killing concentration of about 33 per cent. 
Wood creosote, derived from the destructive distillation of Douglas 
_ fir, compares very favorably with coal-tar creosote, notwithstanding 
_ its water content of over 8 per cent. 

Hardwood tar shows moderate antiseptic properties, proving about 
one-half as toxic as the softwood creosote. 
The two carbolineums are much less toxic than the creosotes tested. 
Water-gas tar distillate of low specific gravity appears to be slightly 
less toxic than coal-tar creosote, while the heavier distillate, repre- 
sented by United Gas Improvement Co. 1.07 oil, is so low in toxic 
properties as to appear to be of little value in wood preservation. 
The secret product None-Such Special appears to be more nutrient 
- than antiseptic to fungi, so far as these tests indicate; however, the 
_ physical properties of the substance when injected into. wood may be 
such as to exclude fungous growth and thus to substantiate the 
claims made for it. Durability tests on treated wood are highly 
desired. 
_ Zine chlorid has a killing point almost identical with coal-tar 
_ creosote. 
Table IL also shows that of 14 preservatives tested against Homes 
_ pwnicola 8 totally inhibit growth below 0.5 per cent, 2 between 0.5 and 
1 per cent, 1 at about 7.8 per cent, and the remaining 3 require over 
40 per cent. | 
Sodium fluorid and coal-tar creosote Fractions II, III, and IV are 
all extremely toxic to this fungus, the killing pomts being almost 
identical. 
_ Coal-tar creosote Fraction I and wood creosote are about three- 
_ fourths as toxic as the above; Avenarius carbolineum is about one- 
half as toxic. | 
Zinc chlorid in the Fomes pinicola list stands only tenth in efficiency, 
whereas in the F. annosus list it stands in fifth place. 
The last four preservatives show very low antiseptic properties 
_ toward Fomes pinicola, as they did toward F. annosus. 
_ By comparing the behavior of the two fungi toward the same 
_ chemical substances a marked difference will be observed. With the 
_ exception of zinc chlorid and copperized oil, Fomes annosus is a far 
- more resistant organism than F’. pinicola, the ratio running as high 
_ as 26 to 1 in the case of Fraction IV of coal-tar creosote. 
It has often been noted during the course of the experiments that 
_ Fomes annosus, after a considerable lapse of time, can accommodate 
itself to rather high concentrations of certain preservatives. Its 


‘ 


30 BULLETIN 227, U. S. DEPARTMENT OF AGRICULTURE. 


normal growth is also relatively slow as compared with that of the 
other organism. Sometimes on high concentrations of toxic media 
the fungus would remain dormant from four to seven weeks and then 
begin a slow development. For this reason it has been difficult in 
many cases to find the exact inhibition point of a preservative with- 
out carrying out a large number of long-continued tests. 

On the other hand, Fomes pinicola seems rather sensitive to slight 
changes in concentration, and one can usually judge within a month 
whether the fungus will develop. 

The difference in behavior between these two organisms shows 
how very necessary it is to make only qualified statements when dis- 
cussing the relative toxicity of preservatives toward fungi. We have 
at present no satisfactory way of predicting, except by trial, how a 
given preservative will react on different organisms. 

A direct comparison of toxicities, as given in Table II, shows that 
in many cases essentially the same oui holds, but eee are several 
exceptions, Fractions I and IV of coal-tar creosote and zine chlorid 
being the most conspicuous. 

In Table III the oils used are grouped according to their nature, in 
order to show a direct comparison between wood tar, coal tar, water- 
gas tar, and petroleum products. 

TaBLE III.—List of wood-preserving oils tested, showing relation between their specific 
gravitres, boiling points, and toxic properties. 


[Results marked with an asterisk (*) are approximately correct. ] 


Percentage distilling below— Killing point (per 


cent). 
Preservative. bree a 
. 180° | 215° | 245° | 275° | 305°. | 320° | 36073) homes Fomes 
C. C. C. C. C. C. C. | annosus. | pinicola. 
Wood tar (hardwood)......- 121957427" 31 53) Gna pan MERE PE eo - *1,25 0.75 
Wood creosote (Douglas fir) - 1.052 |*16 = *31 54.7 laveww:en] seca ehote aes | See *, 65 *, 20 
United Gas Improvement 
Co. 1.07 oil, No. 1101. ..... 10584) 2F7 LOY — Eee 16.3 |*22  |*27 56. 4 40+ 40-+- 
Weare tar distillate No. 
PB BSS ae OTe. Aa ae oe '995°|- 353°] 12/8.) 37.7) ,6L27 | 7elL3eS0.srieeeces ©. 65. oan dass 
Conktae creosote: 
GTaGe Cae. ais teas ee a 1.048. | .4.8. 117.8.) 44.4 1:54.11 6752 74 aie «55 . 225 
Practionw...-).s-.t2s-s-2 934.1) 35.15) 78. Sal 28 cae. 4 oe ree ol eer 30 ~ 225 
Fraction) 32.2.5) 1; 003 ‘|*2=3:~ | 30° |*80%) 92%) [oS SSP SPA a cer 
Praclon ile eee 1 Ofb% | ce ee 9 |. 16: 2'| 4952 177. 7 | Sor teens *, 325 125 
Braction. LV 2... 2. -hee 1088))2 82421622288 OL] 2 407. 138. 510545 Sh eee *3.30 * 125 
Traction Wis) 222 sees yd SU) fe ened [mesa ifs ao el 4.1] 10.1 | 48.7 #33, *7,8 
Avenarius carbolineum (sp. 
br at18.8. ©. )c. cee el Do BOG. vse cr LL be 226:-), 6.1) 16,45/229 eee 5.25 -30 
S. P. F. carbolineum (sp. 
eriat 16""C joe eban cscs HR D700 beteeaa te he ee Se ci I S| Ee occ 730" pilaee seg ce an PY ee 
a a oil (sp. gr. at 
ARGS SAS TOES = O37 Has uc) FD ah PO ie 2D 30.2 |*80 40 40-+- 


1 At 60° C. except as stated for the last three preservatives. 


It is interesting to note that the wood-tar and low-boiling water- 
gas tar and coal-tar distillates tested show very similar toxic prop- 
erties, while the carbolineums, which consist in the main of the 
high-boiling constituents of coal-tar creosote, in all cases proved 
much less toxic to the fungi used. 


THE TOXICITY TO FUNGI OF VARIOUS OILS AND SALTS. 31 


The toxicity of water-gas tar products is highly variable, much 
more so than commercial coal-tar products. By decreasing the 
specific gravity the toxicity rapidly increased. The writers do not 
wish it to be inferred, however, that this necessarily means that 
_ water-gas tar and coal-tar products will prove equally efficient under 
service conditions. The present results are merely suggestive. 

The fractionization of coal-tar creosote gives some interesting data. 
In the case of Fomes annosus the three lower fractions proved con- 
_ siderably more toxic than the creosote itself. In the case of F. 
pimeola the four lower fractions were included. In the former case 
Fraction II gave the best results and in the latter the greater toxicity 
fell to Fractions III and IV. This indicates that the middle fractions 
are the most efficient, but to what group of substances the greater 
toxicity is due we are not yet prepared to state. The work of other 
investigators with naphthalene, which is one of the principal con- 
stituents of Fraction II, would seem at least to militate against this 
substance. 

The high-boiling carbolineums, which approach Fraction IV in 
their physical and chemical properties, likewise approach it in their 
toxic properties. 

While the higher boiling constituents proved to be less toxic than 
the lower boiling ones, their greater permanence in wood under 
Service conditions may at least partially offset the lessened toxic 
_ efficiency. 

The poor showing made by copperized oil against both fungi indi- 
cates that adding small amounts of copper in this form to low-toxic 
petroleum or vegetable oils will produce a mixture of doubtful 
| fungicidal value. 


TOXICITY TO FUNGI OF CERTAIN OF THE MORE IMPORTANT PRE- 
SERVATIVES. 


In order to bring together in convenient form for CT ee the 
results secured by various investigators in the use of certain impor- 
tant preservative substances, as well as those originating in our own 
laboratory upon the preservatives mentioned, Table IV has been 
prepared, indicating the salient features of such tests. 

In making comparisons, the sources of error as well as the degree 
_ of refinement which the figures represent, should be fully considered. 


_ Tasie IV.—Toricity of various preservatives to certain wood-destroying and other fungi. 


Culture | Duration of 


Toxic substance. Organism. Toxic point. ‘median fast Investigator. 
A.—INORGANIC COM- 
POUNDS. 
Per cent. 
Ammonium chromate | Coniophora cerebella.| Under 1..... Agar....| 8to 10 days.} Falck. 
[(NH4)2CrO,]. 
mMmmonium fluorid |..... </ EREES SEES see o Ginger Ob costs .G00i.t.| oF On ao ac Do. 


[NH4F], neutral. 


32 BULLETIN 227, U. S. DEPARTMENT OF AGRICULTURE. 


TaBLe LV.—Towicity of various preservatives to certain wood-destroying and other fungi— 


Continued. 
Toxic substance Organism Toxic point, | Culture | Duration of | tavestigator 
: 8 : pot. | medium. test. cater, 
A.—INORGANIC COM- 
POUNDS—con. rhs. 
: cent. . 

Ammonium fluorid....... Coniophora cerebella.| 0. 123. oP, ibe Gelatin .| 4 weeks..... Netzsch. 

Copper 1 fluorid [CuFe+ |..... ID sngcien ae ~aahloasle Under 0.1...| Agar....| 8 to 10 days.| Falck. 
2H. pure. 

aa silico-fluor id [Cu- |..... GOs. .e scare Under 0.05. .]... (0 oe epee OE QOncaeus Do. 

iF], pur 

Coppers eaicehte [CuSO4-+ |.--.. GOt 5 5. 28s eee Unger 1.5 pale, BO. 09-1 o-+4e OR Do. 

5 

Copper sulphate Se eer Molds-« 4..3> oltiees 5 fo.5- te. 8 oe. Gelatin .| 14 days......| Malenkovié. 

Ferric fluorid [FeFs3]....-- Coniophora cerebella.| 0.132........]... WOl 4 weeks.....  Netzsch. 

Merre auphpte [FeSOu+ |..... ce eee oem o Under’2:..... Agar....| 8to10 days.| Falck. 

2 . 

Ferrous fluorid [FeF2]....}.-... Oe ie fe ioe eee OM DDE eecee eam Gelatin .| 4 weeks..... Netzsch. 

Hydrofluoric acid [HF], |..... WOR eee oe See Under 0.01..| Agar....| 8to10 days.| Falck. 
100 per cent. 

Hydrofivoric acid... 32272). .2< QO. wantin tan Sete O0s scat. oe Gelatin .| 4 weeks..... Netzsch. 

ai) eee acid [He |..... Gc septddoees see Under 0.05..| Agar....| 8 to 10 days.| Falck. 

i 

Hydrofluorsilicic acid.....|..... Oise denen oh 2 es OAR aie ae Gelatin .| 4 weeks..... Netzsch. 

Magnesium  silicofluorid |..... GOust 2. esleasee ss Under 0.067.| Agar....| 8to 10 days.| Falck. 
[MgSiF's+6H.0], 95 per | 
cent. 

Magnesium sulphate |..... AOgrite a. athens ot OVER 16=s-alesy co Cc eee I OG 5 venbuss Do. 
[MgSO4+ 7H20]. 

Mercurie chlorid [HgCly]..|...-. OG, Siwtani pees cont Under 0.1....1...00, 35 ae BO ninded “ Do. 

Potassium fluorid [KF], |...-. QO. ca sccee cette Under 0.05..]... G0soc2- |e <“sdOu omens Do. 
pure. 

Potassiuny fimorid . v5. ...-)2 2-5 « G0... = nae soem ene 0.102 Use Gelatin..| 4 weeks.....| Netzsch. 

Sodium chlorid [NaCl]....|..... (0) Seta ee Under 10....} Agar....| 8tol0days..| Falck. 

Sodium chlorid........... MOTdaT se ta coceeease ss ed Denies Gelatin..| 14 days......| Malenkovié. 

Sodium fluorid [NaF).....]...-.. OO oun sisi mais ste eae wetoae eae d0..05-4.:. .G@sheru Do. 

co fluorid, tech. re- | Coniophora cerebella . taae 0.0...) Agere 8 to 10 days..} Falck. 

ned, 

Sodium Mimorid . os acce acisaeee AO-S. . ssaee ee oe a eae 8 Gelatin..| 4 weeks..... Netzsch. 

Sodium fluorid, tech......]| Fomes annosus.......| 0.25......--- Afar; .vaieieas dogs Humphrey and 

Fleming. 
DOS. seceteeteheet. EF. pinieolad ...-3...04 OND (ash afar do.....| 5 to 7 weeks. Do. 

Sodium carbonate [Nas- | Coniophora cerebella . Under 0.1255. 2500t.ee: 10 days.....- Rumbold. 
COs]. 

So aie um _ silico-fluorid |..... GO. Sate siec ates Under 0.1. -..|...do.....] 8to10 days. .| Falck. 
[NaeSiFs], about 100 per ; 
cent. 

Sodium silieo-fluorid:.../.)2..:.d0.....<e¢e.ssese 05208 cine ee Gelatin..| 4 weeks..... Netzsch. 

Zine chlorid [ZnCly].......|.---- AOlsc cee aeons Under 0.5...} Agar...-| 8to10days..| Falck. 

Wate CHIOTID . nics is ctw soe Leet CC Pee ae ee pee 1 fe OOse se 8 days.....--| Rumbold. 

and 2. 
DO: See heentiaee ses oe Lenzites sepiaria.....|..... GOs aoe do....-|.. 72, Gee eee Do. 
DO sex extios then nc eres Polystictus hirsutus.|...-. GOP See 5s G0.5-=|2 desea oeeeere Do. 
DOS hi. A esotiaw sete Pywersicolora.. aaacee Over'2is.. cclese 0. s+02|2 aa One ee Do. 
Zinc chlorid, commercial. .}| Fomes pinicola.......| 0.75.....----|.-. 0.....| 4to 8 weeks.. peers. and: 
es 
DOs x. fzggs $3804 bs de FE’. BANOSUB 4S: cccr 5 g¥e Obes Fa.gey sale des,-% 5 to 7 weeks... Do. 

Zine fluorid [ZnF»2].....-- Coniophora cerebella .| 0.186....--..- Gelatin..| 4 weeks....-. Netzsch. 

Acid zine fluorid, tech....|..-.. COs. se hoseet sie pene 0.1...} Agar....| 8to1l0days..| Falck. 

Ace zine fluorid [ZnF2- |...-- rs ye Rone apg 3 ji BM Ste Gelatin..| 4 weeks.....| Netzsch. 

Zine silico-fluorid.........|....- 50 10 Sees A ai ahaa ie O59 S 2. jae 0-22)... dOueaees ie Os 

Zinc silico-fluorid [Zn- |..-.. GOs Aeree. tes lee Under 0.1...| Agar..-. 8 to 10 days..| Falck. 
SiFe+6H20]. 

Zine sulphate [ZnSO4+ |-....-do..............-. Under’... 54... 0.2.2: )s fa Oees sae Do. 
7H20). 

B.—ORGANIC COMPOUNDS. 

(a) Benzol and phenol de- 

rivatives. 

Anilin [CsHsNHz)]........-| Coniophoracerebella .| Under 1.. Agar....| 8tol0days..| Falck. 

Cresol [CsH4CH30H]....-..|..... GO. os. nef dt ink Under 0.125.|...do..... 8 days.......| Rumbold. 

CresOlite itann Bava eee Lenzites sepiaria.....|.....d0......|... dO 2. c0.|s see tO One eee Do. 

TNO Ses aphe se Seto eee Polystictus versicolor |..... 06 (oe ee do2.ss.|....2 edOeeumee Do. 

0 eee aoe to P. Rirsitts. 25542. Under 0.25..]... d0.002.\. 2). sere Do. - . 
Crésol, piireis <2. Ate: Pettieilliumy.: i: 5..2% Under 0.05. .|... d0e. 5. 4 weeks..... J. M. Weiss. 
Cresol’ eleirial gare leres ete Coniophora cerebella. Beles 1 Feo eee 8 days.......| Rumbold. 

and 2. 
DOe.cstoM S| SER Lenzites sepiaria..... Over: 2 Ione dowise: {2235 aden. Do. 
DO FE sets he atic Polystictus versicolor | Between 1 |...do.....].....d0...... Do. 


and 2. 


THE TOXICITY TO FUNGI OF VARIOUS OILS AND SALTS. a0 


‘ 


TasLe 1V.—Tozicity of various preservatives to certain wood-destroying and other fungi— 


Continued. 
Toxic substance. Organism. Toxic point. ere D oe of 
B.—ORGANIC COMPOUNDS— 
continued. 
(a) Benzol and phenol de- 
rivatives—Continued. 
Per cent. 
Cresol calcium...........- Pe MIrsutuses. - 22s -e Be 1) Agar... .|8 dayssa: 2.2 
and 2. 
Oe eaice ae cece lea sis Fomes annosus.......| Bet ween |.-..do..... 4to7 weeks... 
0.14and 0.28. 
Dinitro-p-cresol [CeH:- | Coniophora cerebella.| Under 0.1. ..|...do..... 8to10days. 
(NO2)2CH30H]. 
Sodium salt ‘of ¢ 
Dinitro-p-cresol, 21 |..... (OO) Ses ere, See ee Under 0.01../--- Gasser eae dsc. a 
per cent.! 
1:2  dinitro-o-cresol, |..... CERES Saree Wnder 0:03.20 O-s5-c\aaaq snd Oe a2 5 ae 
31 per cent.! 
4:6 dinitro-m-cresol, |..... Omer eh ties Nae Under 0.005 dozens SCO, hese 
59 per cent. 
Gallic acid [C7Hs05+H20]]..... GORA Soe ceeoie oe Under 2....-\.3: dozss iG oat aoe 
aa acid [CigHio- |..... OME Serene os Nemesia. eee doses CO (Oe ales 
Phenol (CgH;OH]......-...]..... CC everaateh mide ied Ses Se Le agha (A ao Nae ale Se 6" a 
Phenol, pure..........-.-| Penicillium..........] 0.15.......-.].-- doe 4 weeks....- 
oe hae [CeH4- | Coniophora cerebella. Under 01022 2 |= s2dorses. 8 to 10 days. - 
2 : 
P-nitrophenol...........-|..... Gowns. re Rees Wider OOS 2. doses. 4\--4-20d0=coe ee 
Sodium salt of— 
oi oe ea 63 per |..... GOe er co wase ene Winder0l0032|2--d0s-5=-|2-24--00--2 4-- 
cen 
aos ine 60 per |..... COG. Sie ae ee ee Under 0.025\.|.22d0s22-.| 2.5: do. fe: =: 
cen 
2:4 dinitrophenol [Cz- |..... CIO et Se 5 a aa WnderOlOlssiee sdoss..2\- sed Ose are 
H3(NOz2)20H]. 
2:4 ame Bae le bee CON a mey te cakrcros oi Unider’0/0033|-c.do0e.--4|-422-d0.25-.: 
er ce 
Sayeed. [CeH4OH- |..... CC a» Sead) ili ete Minder dd. ..f sedovss4 5.300. 05s 2 
Sodium picrate [CgH>- |..... COLOR Slag: a a get oe Under 0.04. .|-.-- GOs.F2) |Vaa-edo: SLs 
(NO2)s0Na], 40 per 
cent. 
Thymol [CeH3sCH3C3Hr- |-.... (COS Soa scaeUmder 001, 3|2ndornay. 2 /dGs 9 u2¢ 
OH}. 
(b) Tars and creosotes. 
Coal-tar creosote: 
Straight run, Ameri- | Penicillium.......... (Hibjee eae Agar....| 4 weeks....- 
oan §8; gr. 1.049 at 
5 per cent gum-arabic | Polystictus versicolor.| 0.25-0.40... MCOLees RS 2 2 ote ce 
emulsion. 
eo (sp. gr. 1.09 | Molds......---....... OID Synee Mee: doses. 4 weeks...-- 
a 
Sp. gr. 1 .048 at 60° C..! Fomes pinicola....... Oia oe 2y i dosesee 4 to 6 weeks 
5 per cent gum-arabic | F. annosus..........-. ISDE, tooo pe ldO se eulteee sd Os ee ee 
emulsion. 
eras &P gr. 1.062 | Coniophora cerebella.| Under 0.125.|.-.do..... 8 days...-..- 
a 
eGR Sete: OS. Lenzites sepiaria. _... Under 0.125 .|.-.do.....|...-.do... 
ID Soo Polystictus versicolor .| Under 0.25. .|--.do.....|----- Gosees 
Ll iP, hirswbusy ss a... 2: Vrader,W250.\2 Fadots 5 ho} dors. 2 
Carbolineum: 
Avenarius (sp. gr. | Fomes annosus....... 2s tales ll oe dos.c.z 4 to 10 weeks 
1.126 at 16.5° C.). 
DOS Se. Sa e F. pinicola........... OOF eee: ad doves. 5 to 6 weeks. 
s. Gane &P. er t.127 | F. aNMOSUS. <2 5..--- Cae ae ee a (yaaa 5 to 8 weeks. 
a V& 
Coal-tar creosote: 
With bases, acids,and | Penicillium..._....... Or 85.5 ene eee EGOn 33 4 weeks. ..-- 
solid hydrocarbons 
removed. 
With 20 per cent tar |..-.. UR ye Sot Bees ESS acer e FAG <2. =| geeMOuats 
acids added. 
With 20 per cent pure |....- QO pst adeeee 8 eG Onde tece see eos. wed Ons 
naphthalene added. 
With 5 per cent fil- |..... (6 La ieee te etal Ona ee nse eee Gore lees = 300s... 
tered tar added. 


1 Toxic value based on 100 per cent pure salt. 


Investigator. 


Rumbold. 


Humphrey and 
Fleming. 


.| Falek. 


Do. 


Do. 
Do. 


Do. 
J. M. Weiss. 
Falek. 


Do. 


J. M. Weiss. 


Dean and 
Downs. 
J. M. Weiss. 


., Humphrey and 


Fleming. 
Do. 


Humphrey and 
Fleming. 
Do. 
Do. 


J. M. Weiss. 


34 


BULLETIN 


227, U. S. DEPARTMENT OF AGRICULTURE. 


TaBLE IV.— Toxicity of various preservatives to certain wood-destroying and other fungi— : 


Continued. 
Toxic substance. Organism. Toxic point. yee D siren of | Investigator. 
B.—ORGANICCOMPOUNDS— 
continued. 
(b) Tars and creosotes— 
Continued. 
Coal-tar creosote—Contd. Per cent. 

With 10 per cent fil- | Penicillium.......... bo Boat Agar....| 4 weeks .....| J. M. Weiss. 
tered tar added. 

With 20 per cent fil- |..-... 00.2505 Asa OBO ese See do. .2..|-/-2 -dOceoeee Do. 
tered tar added. 

Coal tar (undistilled, sp. | Molds........-....... Between 1.5 |...do.....|....-d0....... Do. | 
gr. 1.194 at 15.5° C.). and 2. 
Coal-tar creosote: 

Fraction I (sp. gr. | Fomes annosus 25.) Deen 2) =) i 4 to 6 weeks.| Humphrey and 
0.934 at 60° C. 8. 3 Fleming. 
per. cent distills be- 
low 215° C.). 

Doda sates sen EF} pinicola. 32.2 5252-2 995 ey ee d0..3<5|22e0 dose Do. 
Fraction II (sp. gr. annosus........-.. OST. 5 .i5~ else ri Fs nae 5 to 9 weeks Do. 

1.003 at 60° C., 9 per 
cent distills below 
205° C., 95.9 per 

cent below 287° C.). 

DOs. 22S ee* : pinicola .:. 2.252 O15 ee. cel oe do..... 4 to 5 weeks. Do. 

Fraction III Gp. PY PSA@nnosnset pecs. se O32aoeaceecleee G0.scck 4 to 8 weeks. Do. 
1.045 at 60° C., 73.7 
per cent distills be- 
low 295° C.). 

Wore aie kA ee Ei pinieolact 3: 32¢. 3.2 G25. tle aceeee dois2: 4 to 7 weeks. Do. 

Fraction IV (sp. gr. | F. annosus........... cE AE ape iS dons. 4 to 6 weeks. Do. 
1.088 at 60° C. 13 
per cent distills be- 
oo 285° and 320° 

Doe! .-. coos ¥' pini¢ola..}......de0e OY | rn bt do..5:; 5 to 8 weeks. Do. 

Fraction V (10 per | F. annosus........... Boe sas osece ee dos: 4 to 6 weeks. Do. 
cent distills above 
320° C., 36.6 per 
cent hard residue). 

Li See ee FY. pinicola.. «... <. 5-0: Fes oi sidridnim oe Pe Ss ae 5 to 8 weeks. oO. | 
Fraction below 235° C.| Penicillium......:...| 0.85.......--|..- done: 4 weeks....- J. M. Weiss. 
Fraction between |..... GOK S55. He ee coe O25: a2 aeeelces doe 43,002.72 0. 

235°-272° C. 
Fraction above 272° C.|.-.... CC earn ay Sa a gee Breen. 4 dow.ct) eee dovsseee~ Do. 

and 4.5. 

Anthracene, pure.........|..--. i Coe ae Np Above 10....|... do.....)5-3-20eesuea Do. 

Naphthalene, pure.......|.---. gos. S saeco Between 9 |...do.....|----.d0.....-- Do. 
and 10 

Quinolin, Pures -. o.<s0-%~ 2 | 208 i Ee eee ee ht: eee eee! mer G0: .. oss aae eae Do. 

Parafiin, OGG a6 oss cede ee GAs tik can deere Above 10....|... do. 2% |-...- aoa Do. 

Water-gas tar distillate: 

Fraction between | Polystictus versicolor | 0.40.........]... do2teh. 86 Pe Dean and 
170°-340° C f owns. 

Fraction between} Penicillium.........-. Dias none sultoeeeee dowcec: 4 weeks....- J. M. Weiss. 
170°-315° C. (sp. gr. ; 

1.024 at 15.5°C.). 

Fraction Sh hae te Sep sra 6.0: as res Above 10....|... dO. <.s6|-.oanueaeeen Do. 
210°-315° C. (sp. 

1.053 at 155°C.) # 

United Gas Improve- | Fomes annosus.....-. Above 40....]... do..... 4 to 8 weeks.| Humphreyand 
ment Co. oil (sp. gr. Fleming. 
1.058 at 60° C.). 

DO. 2 3. dae ee FP: pinitoia.t....c5.. Above 40....]... d0.ccs2 4 to 5 weeks. Do. 

Sp. gr. 0.995 at 60° C..| F. annosus........... aeoue 0.65 3:dois88 5 to 8 weeks. Do. 

Wood creosote (softwood, | ....do......-........| 0.65.....-.../... do: 4 to 7 weeks. Do. 
sp. gr. 1.052 at 60° C— 
about 8 per cent H20). 
Dios. cee setestss ¥: pinteolact , <2. sess 0:20 e. ia 5 Ee dost 4 to 6 weeks. Do. 
Wood tar (hardwood, sp. 5 SATEOSTIS hy, 2 csie ob ace SoBe aids adhe Cc pee ae dO exis a8 Do. 
gr. 1.195 at 60° C.). 
DOu eu ee a teoedan ae Fpinieola.is4-<5--- C1 ej: AEE hoa rc) pe NOsd2e 4 to 5 weeks. Do. 
Semiasphaltic petro- | Penicillium.......... Above 10....]... do... weeks..... J. M. Weiss. 


leum (sp. gr. 0.973 at 
15.5° C.; distills above 
315° C.). 


In conclusion, the writers wish to emphasize that any scale of 
toxicities derived from Petri-dish tests on the usual nutrient agar or 


THE TOXICITY TO FUNGI OF VARIOUS OILS AND SALTS. 35 


gelatin media, even when the tests are conducted-under exactly 
similar conditions, do not necessarily represent the true relative 
- toxic values of the different compounds, for the interaction between 
the toxic compounds, the nutrient substances contained in the 
media, and the plant protoplasm is variable and more or less specific 
for each combination. 

Also, the reader should keep before him the fact that toxicity alone 
_ is not the sole criterion in judging the service value of a preservative, 
and a direct application of these data to that end would in many 
cases lead to very erroneous conclusions. 

In many cases it is possible to overcome such unfavorable proper- 
ties in a preservative as high solubility in water by placing the treated 
timber under conditions less exposed, and such timbers treated with 
soluble preservatives, such as sodium fluorid, zinc chlorid, and copper 
sulphate, should behave more or less according to the toxic ratios 
_ represented. The same should apply to oils of similar volatile and 
soluble properties placed under approximately similar service con- 
ditions. 

Not all preservatives are adapted to the same uses, and in testing 
their service value these primary facts should be given full consider- 
ation. We have long been in the habit of taking as the standard 
test of the efficiency of a substance its ability to protect timber 
exposed to such extreme conditions as are railway ties, telephone 
_ poles, posts, exterior building timbers, etc. This standard is very 

often too severe, and for this reason preservatives should be grouped 
- according to the conditions under which they are to be exposed. 


SUMMARY. 


A survey of the work of various investigators on the action of 
different toxic substances on the higher and lower forms of plant life 
_ discloses a marked difference in behavior. The action of toxic agents 
appears to be specific, being highly poisonous to certain organisms 
and only moderately so to others. 

Very dilute concentrations ordinarily produce a stimulative effect. 

_ Among the fungi, as a rule, the common molds are more resistant 
_ to poisons than the true wood-destroying fungi, and even among the 
latter group the different species show a great difference in suscepti- 
bility. 
_ The chemical and physical composition of the media supporting 
_ the growth of the fungi determines, to a large extent, their develop- 
ment. The presence of certain kinds of insoluble matter or of such 
_ organic compounds as sugars and proteid materials, with which the 
_ toxic agents may possibly react, often introduces a considerable 
element of error when testing the toxic value of a substance by 
- mixing it with nutrient agar or gelatin media. 


36 BULLETIN 227, U. S. DEPARTMENT OF AGRICULTURE. 


Temperature is also an elemental factor in the growth of fungi, and 
there is an optimum for each organism, often lying within a very 
narrow range. The growth activities of fungi probably bear a close — 
relation to the resistance offered toward toxic agents. 

The toxic elements or radicals in a compound are often difficult to 
determine. In the case of heavy metallic salts, it is the metal ion; 
in the case of strong inorganic acids, the hydrogen ion is said to be ~ 
the important element; in the fluorin compounds, fluorin is the 
determining agent; in the case of certain phenols, the introduction 
of halogen, alkyl, or nitro groups is said to increase toxicity. Even 
in the case of isomeric compounds the grouping of the radicals plays 
an important part. : 

The Petri-dish method of determining the toxicity of a substance 
offers a ready procedure which gives indicatory results in a short time, 
On account of certain sources of error, some inaccuracies must be 
admitted, although the methods employed by the writers obviate 
many of these. | 

The results of tests on 18 wood preservatives at the Forest-Products — 
Laboratory, against two wood-destroying fungi, Fomes annosus Fr. 
and I. pinicola (Sw.) Fr., are given. The preservatives act in a 
considerably different manner on these two organisms, the former 
being, as a rule, far more resistant. : 

The tests show that for these two organisms the following quan- 
tities of preservative per cubic foot of culture medium used are suf- 
ficient to inhibit all growth: 


FOR FOMES ANNOSUS. FOR FOMES PINICOLA. 
Pounds. Pounds. 
Coal-tar creosote, Fraction IT 0. 14 | Coal-tar creosote: 
Sodium fimorid.:. oi. 0% .16 Fraction 1] 4G ee , 0. 08 
Cresol calcium......--..... 0. 09- .18 Fraction TV ii ogee  .08 
Coal-tar creosote: | Fraction. lif shee . 09 
PrACuON Lo. oa. Meo tyes . 19, |. Sodium fluorid 23.25. .09 & 
Hraction DE. OS o2.50220 .20 | ‘Wood creosote. ..: 22 eae 13 

ZAG, CHIOING oe: siete at a . 31 | Coal-tar creosote: 
Coal-tar creosote, grade ©... . 34 Grade O's. 2. 0 AGG ae .14 
Water-gas tar distillate (sp. Fraction ,.. 732¢32eeme 14 

PTO. OD Nn sri eels ie .41 | Avenarius carbolineum .... .19 
Wood creosote.......------ . 41] Zine chlorid... .. 5252 eeeue .47 
Hardwood tars.....-...--.- . 78 | Hardwood tar...2 5224-0 .47 
Coal-tar creosote, Fraction IV 2.06 | Coal-tar creosote, Fraction V 4, 87 
S) Pi carbolineum. 20: 2.8 | Copperized oil............. Over 25 
Avenarius carbolineum .... 3.27 | United Gas Improvement 
Coal-tar creosote, Fraction V . 20. 59 Co.;-1,07 oil 3. -enes anges Over 25 
Copperized elo. fue. ai: 25 | None-Such Special......... Over 25 
United Gas Improvement 

Coser onl: e-re" 22° Over 25 ” 
None-Such Special. ........ Over 25 


Sapwood antiseptic ........ Over 25 


BIBLIOGRAPHY. 


. Boxorny, THomas. Einwirkung von Metallsalzen auf Hefe und andere Pilze. 

In Centbl. Bakt. [etc.], Abt. 2, Bd. 35, No. 6/10, p. 118-197, 1912. 

. Brooxs, CHarLes. Temperature and toxic action. In Bot. Gaz., v. 42, no. 5, 

p- 359-375, 1906. 

. CuarK, J. F. On the toxic effect of deleterious agents on the germination and 

development of certain filamentous fungi. Jn Bot. Gaz., v. 28, 1899-1900: no. 5, 

p. 289-327; no. 6, p. 378-404. 

. Dean, A. L., and Downs, C. R. Antiseptic tests of wood-preserving oils. Jn 

Orig. Commun. 8th Internat. Cong. Appl. Chem., v. 13, Sect. 6a, p. 103-110 

[1912]. 

. Faucx, Ricoarp. Wachstumgesetze, Wachstumfaktoren und Temperaturwerte 

der holzzerstérenden Mycelien. Jn Moller, Alfred. Hausschwammforschungen. 

Heft 1, p. 53-154, 1907. 

Die Lenzitesfaiule des Coniferenholzes, eine auf kultureller Grundlage 

bearbeitete Monographie der Coniferenholz bewohnenden Lenzites-Arten. In 

Moller, Alfred. Hausschwammforschungen. Heft 3, 234 pp., 24 fig., 7 pl., 1909. 

Die Merulius-faiule des Bauholzes. Neue Untersuchungen tiber Unter- 

scheidung, Verbreitung, Entstehung und Bekimpfung des echten Hausschwam- 

mes. Jn Moller, Alfred. Hausschwammforschungen. Heft 6, 405 p., 73 fig., 

17 pl., 1912. 

. Frrcn, Rusy. The action of insoluble substances in modifying the effect of 

deleterious agents upon the fungi. Jn Ann. Mycol., v. 4, no. 4, p. 313-322, 1906. 

. Frep, E. B. Uber die Beschleunigung der Lebenstitigkeit hoherer und niederer 
Pflanzen durch kleine Giftmengen. Jn Centbl. Bakt. [etc.], Abt. 2, Bd. 31, 
No. 5/10, p. 185-245, 1 fig., 1911. 

. GuéeuEN, F. Action de divers antiseptiques sur le Penicillium glaucum. In 
Bul. Soc. Mycol. France, t. 15, fasc. 1, p. 15-23, 1899. 

. Harvey, H.W. The action of poisons upon Chlamydomonas and other vegetable 
cells. Jn Ann. Bot., v. 23, no. 90, p. 181-187, 2 fig., 1909. 

. Heap, F. D. On the toxic effect of dilute solutions of acids and salts upon 
plants. In Bot. Gaz., v. 22, no. 2, p. 125-153, pl. 7, 1896. 

. Horrmann, Karu. Wachstumverhiltnisse einiger holzzerstérender Pilze. In 

_ Ztschr. Naturw., Bd. 82, p. 35-128, 1910. Also reprinted as Inaugural Disserta- 

tion, Konigsberg in Pr. 


. KAHLENBERG, Louis, and Truz, R. H. On the toxic action of dissolved salts 
and their electrolytic dissociation. Jn Bot. Gaz., v. 22, no. 2, p. 81-124, 1896. 

. Ketterman, K. F. The excretion of cytase by Penicillium pinophilum. In 
U.S. Dept. Agr. Bur. Plant Indus. Circ. 118, p. 29-31, 2 fig., 1918. 

. Lz Renarp, AtFrRepD. Influence du milieu sur la résistance du Pénicille crustacé 
aux substances toxiques. Jn Ann. Sci. Nat., Bot., s. 9, t. 16, no. 4/6, p. 277-336, 
1912. : 

. McCurntic, T. B. Chloride of zinc as a deodorant, antiseptic, and germicide. 
U.S. Public Health and Marine Hosp. Serv. Hyg. Lab. Bul. 22, 24 p., 1905. 

37 


38 BULLETIN 227, U. S. DEPARTMENT OF AGRICULTURE. 


18. Matenxkovi¢é, Basitrus. Zur Lehre und Anwendung der Holzkonservierung 
in Hochbaue. Mitt. Gegenst. Artil. u. Geniew., [Vienna], Jahrg. 35, 1904, p. 
311-333. 


19 


Die Holzkonservierung im Hochbaue mit besonderer Riicksichtnahme 
auf die Bekimpfung des Hausschwammes, 301 p. Vienna, 1907. For French 
translation of first part see Ann. Agron. s. 3, ann. 6, sem. 1, No. 3, p. 161-211, 
1911. 


20. 


Uber den Zusammenhang zwischen der Zufuhr von Antiseptikum und 
der Lebensdauer bei impragnierten Holzmasten. In Elektrotek. Ztschr., 
Jahrg. 34, 1913, Heft 16, p. 436-439. | 

21. Nerzscu, J. Die Bedeutung der Fluorverbindungen fiir die Holzkonservierung. 
In Naturw. Ztschr. Forst u. Landw., Jahrg. 8, 1910, Heft 8, p. 377-389. 

22. Ono, N. Zur Frage der chemischen Reizmittel. In Centbl. Bakt. [etc.], Abt. 2, 
Bd. 9, No. 5/10, p. 154-160, 1902. 

23. Puust, Cary. Die Widerstandfihigkeit einiger Schimmelpilze gegen Metallgifte. 
In Jahrb. Wiss. Bot. [Pringsheim], 1902, Bd. 37, Heft 2, p. 205-263. 


24. Ravin, Jutes. Etudes chimiques sur la végétation. Jn Ann. Sci. Nat. Bot., 
s. 5, t. 11, p. 93-299. Also reprinted, Paris, 1870. 


25. RumBo.p, CaRoLine. Uber die Einwirkung des Siure- und Alkaligehaltes des 
Nahrbodens auf das Wachstum der holzzersetzenden und holzverfarbenden Pilze; 
mit einer Erérterung tiber die systematischen Beziehungen zwischen Ceratosto- 
mella und Graphium. Jn Naturw. Ztschr. Forst u. Landw., Bd. 9, Heft 10, | 
p. 429-465, 22 fig., 1911. . 

26. SEIDENSCHNUR, F. Wood preservation, 1911. Advertising pamphlet pub- 
lished by Hiilsberg & Co. 

27. TurELE, R. Die Temperaturgrenzen der Schimmelpilze in Verschiedenen 
Nahrlésungen, 37 p., 6 pl. Leipzig, 1896. 

28. TruE, R. H. The toxic action of a series of acids and of their sodium salts on 
Lupinus albus. Jn Amer. Jour. Sci., s. 4, v. 9, no. 51, p. 183-192, 1900. 


29. and Girs, W. J. On the physiological action of some of the heavy metals 
in mixed solutions. Jn Bul. Torrey Bot. Club, v. 30, no. 7, p. 390-402, 1903. 

30. and HunxeL, C. G. The poisonous effects exerted on living plants by 
phenols. Jn Bot. Centbl., Bd. 76, 1898: No. 9, p. 289-295; No. 10, p. 321-327; 
No. 11, p. 361-368; No. 12, p. 391-398. 

Sl. and OGLEVEE, C. 8. The effect of the presence of insoluble substances on 


the toxic action of poisons. In Bot. Gaz., v. 39, no. 1, p. 1-21, 2 fig., 1905. 

32. Wziss, H. F. Tests to determine the commercial value of wood preservatives. 
A progress report. Jn Orig. Commun. 8th Internat. Cong. Appl. Chem., v. 13, 
Sect. 6a, p. 279-300, 5 fig. [1912]. , ; 

33. Weiss, J. M. The action of oils and tars in preventing mould growth. In 
Jour. Soc. Chem. Indus., v. 30, no. 4, p. 190-191, 1911. 

The antiseptic effect of creosote oil and other oils used for preserving 

timber. Jn Jour. Soc. Chem. Indus., v. 30, no. 23, p. 1348-1353, 1911. ; 


O 


34. 


| ADDITIONAL COPIES 
OF THIS PUBLICATION MAY BE PROCURED FROM 
| THE SUPERINTENDENT OF DOCUMENTS 
GOVERNMENT PRINTING OFFICE : 
WASHINGTON, D. C. 
; AT 


10 CENTS PER COPY | 


4 


x 
fr * 
~ 
- 
) 
4 
> 
. “Fy 
‘ 
= hs 
‘ S 
gh! 
ee) 
be 
yo aks 


Bee PEN Or EAL 


{ e) USDEDARTNENTOF AGRICULTURE € 


No. 247 


Contribution from the Bureau of Plant Industry, Wm. A. Taylor, Chief. 
July 20, 1915. 


(PROFESSIONAL PAPER.) 


_A DISEASE OF PINES CAUSED BY CRONARTIUM 
: PYRIFORME. 


_ By Grorce G. Hepacock, Pathologist, and Wiu1aAmM H. Lona, Forest Pathologist, 
Investigations in Forest Pathology. 


CONTENTS. 

Page. Page. 
Muswry Onine MiNpus.........25...4------.-- 1 | Dissemination of the fungus................- 12 
Morphology of the fungus................---- 2 | Effect of the fungus on its host plants.......- 13 
Synonymy and description of the fungus...- 3 Effect of the «cial form on pines........-. 13 

Inoculation experiments with the fungus... 5 Effect of the uredinial and telial forms on 
Distribution of the fungus...............---- 8 Comandra plants. 4-22... 085. soe. cden8 16 
Distribution of the «cial form........... 8 | Eradication and control of the fungus........ 16 
Distribution of the uredinial and telial Ieiterabune'CHed.oe . s\cckGunes caps bweviows apie 20 

MASP SEG Sine soc pcecwce costes. 9 


HISTORY OF THE FUNGUS. 


In 1875 Peck (10)! described as a new species under the name Peri- 
_dermium pyriforme a caulicolous or stem-inhabiting Peridermium with 
_ obovate to pyriform spores from a specimen collected by J. B. Ellis 
(No. 2040). In 1882 Ellis issued in his North American Fungi under 
No. 1021 a caulicolous Peridermium which he called ‘‘Peridermium 
 pyriforme on small branches of Pinus virgyumana,” and in the Ellis 
Herbarium, now at the New York Botanical Garden is a specimen 
labeled ‘‘Peridermium pyriforme on small branches of Pinus rigida, 
Newfield, New Jersey, May, 1890.” Both of these latter specimens 
appear to be Peridermium comptomae; at any rate, neither of them is 
the true P. pyriforme originally described by Peck. Arthur and Kern 
(1) in 1906 described as P. pyriforme Peck what is now known as P. 
-comptoniae. 

‘In 1913 the writers received from Prof. E. Bethel a caulicolous 
‘species of Peridermium on Pinus contorta, which they described as a 


a _ 1 Reference is made by number to “ Literature cited,’’ p. 20. 


_ Nors.—This bulletin discusses an important disease of pines which is now for the first time fully de- 


culturists. 
93041°—Bull, 247—15——1 


2 BULLETIN 247, U. S. DEPARTMENT OF AGRICULTURE. 


new species, Peridermium bethelt (6). The type material P. pyri- 
forme was not accessible at the time the article was prepared, as all © 
of Peck’s specimens were packed up and in transit from the old to 
the new quarters of the New York State Museum. The writers there-— 
fore had to depend upon Arthur and Kern’s published statement con- 
cerning this species (1, p. 420). The spore measurements also of the 
typical P. pyriforme did not correspond, since the length of spores of | 
the eastern species as given by Peck in. his original description was | 
too great. While this article by the writers (6) was in press, Arthur — 
and Kern published an article (2) in which they discarded their earlier — 
interpretation of P. pyriforme and admitted that there is a species of ~ 
Peridermium with typical ‘‘pyriform, obovate, or oblong-pyriform | 
spores,’ just as Peck had originally described it in 1875 (10), and — 
that their original assignment of P. py*iforme Peck to what is now 
known as P. comptoniae was an error. They also suggested that the _ 
alternate stages of this Peridermium would probably be found on ~ 
species of Comandra. b | 

Orton and Adams (9), in 1914, published an article on Peridermium 
from Pennsylvania, in which they discussed Peridermaum comptoniae ~ 
and P. pyriforme. ‘They described the finding of a caulicolous species _ 
of Peridermium at Charteroak, Huntingdon County, Pa., on the 
trunks of Pinus pungens, which proved to be the true Peridermium 
pyriforme of Peck. Subsequently Cronartium comandrae was found 
within 40 feet of the infected pines and the conclusion reached that 
this Cronartium is the alternate stage of Peridermvum pyrivforme. 
They also state that P. bethelt is probably a synonym of P. pyriforme. 
In May, 1914, Arthur and Kern in a general discussion of the North 
American species of Peridermium inhabiting pines (3) gave the syn- 
onymy of P. pyriforme, a technical description, and an explanation ~ 
of their change of opinion regarding the species. 

In June, 1914, the writers published culture data (8) showing that 
successful sowings of the eciospores of Peridermium pyriforme had. 
been made on Oomandra umbellata, thus completing the life cycle of 
this interesting rust and proving that its alternate stage was the 
Cronartium found on Comandra. 


MORPHOLOGY OF THE FUNGUS. 


The macroscopic characters of Peridermium pyriforme are practi- 
cally identical on all the hosts examined by the writers, but there 
are some differences in the microscopic characters, especially in the 
shape and size of the eciospores. This difference in size and shape 
of the spores may be due to the influence of the cial host; that is, — 
they may vary according to the species of Pinus which the Perider- — 
rium inhabits. In specimens of the rust on Pinus contorta (Fl. I, 


A DISEASE OF PINES CAUSED BY CRONARTIUM PYRIFORME, 3 


fig. 4) from Colorado, some of the eciospores are very short and — 
‘slightly acuminate, while many are ellipsoid or even globoid (PI. I, 
fig. 3). In specimens on Pinus pungens from Pennsylvania many of 
the spores are nearly twice as long as those from Pinus contoria, 
the acumination’is very marked, and the spores are rarely ellipsoid 
mel. I, fig. 2). 

 Peck’s type material of Peridermium pyriforme is in the New 
‘York State Museum, at Albany, N. Y. It consists of a split branch 
4 em. long, 1 cm. thick at one end and 0.5 cm. thick at the other; 
the weak, fragile peridia barely protrude beyond the bark. The 
‘split surface of the twig is glued to the yellow paper bearing one of 
the legends. The specimen is in fairly good condition and most of 
the essential characters, both macroscopic and microscopic, can be 
determined from it. What appears to be the other half of this speci- 
“men is at the New York Botanical Garden, Bronx Park, N. Y., but 
it is much insect eaten and but little can be determined from it. 

_ The type material at Albany bears the following legends on the 
box: “ Peridermium pyriforme, Newfield, N. J. Ellis #2040.” On 
the original wrapper is ‘ Peridermium pyriforme on pine limbs in 
‘the spring, Newfield, N. J. .0015-.0025. No. 2040 Ellis.’’ This 
legend is in two parts. The name is in Peck’s handwriting, with a 
drawing of a spore and size of spores in pencil, while the host, loca- 
tion, and number of the specimen are in ink and are in Ellis’s hand- 
writing. The word “type” is not in the original legend. The fol- 
lowing is Peck’s original description of Peridermaum pyriforme (10) 
and his remarks on the same: 

_ Peridia erumpent, large, white when evacuated, the cells subrotund, with a paler 
margin, marked with radiating striations, spores obovate, pyriform, or oblong- 
‘pyriform, acuminate below, .0015-.0025 inch long. 

Bark of pine branches. The specimen is labeled “Newfield, N. J.,” but Mr. Ellis 
informs me that it may have been collected in Georgia and placed by podem among 
his New Jersey specimens. 

q In the dried specimens the peridia are mostly compressed, about one-fourth of an 
inch long, and scarcely exserted above the surface of the bark. The spores are pale 
yellow, but probably they are more highly colored when fresh. The acumination is 


generally acutely pointed, and it is sometimes so elongated as to make the spore 
appear clavate. It is one of the most distinctive features of the species. 


SYNONYMY AND DESCRIPTION OF THE FUNGUS. 


Cronartium pyriforme (Peck) Hedge. and Long, 1914, Alternate Stage of Peridermium 
Pyriforme. 
Cronartium asclepiadeum thesir Berk., 1845, in Lond. Jour. Bot., v. 4, p. 311. 


C onartium thesit (Berk.) Lagerh., 1895, in Troms¢ Mus. Aarsh., v. 17, p. 94. 
Perivdermium betheli Hedge. and Long, 1913, in Phytopathology, v. 3, No. 4, p. 251. 


 Pyenia unknown. 


4 BULLETIN 247, U. S. DEPARTMENT OF AGRICULTURE. — 


AKcia caulicolous, appearing on branches or trunks, forming le- — 
sions or fusiform swellings 2 to 30 cm. long (Pl. I, fig. 3); sori scat- 
tered or somewhat confluent in small groups, rounded or irregular, 
2 to 6 mm. long by 2 to 4 mm. wide by 1 to 2 mm. high; peridium ~ 
usually only slightly protruding from the bark, bladdery, subhemi- | 
spherical, rupturing irregularly along the top and sides, without con- | 
colorous processes, about 2 cells thick, outer surface minutely and © 
rather closely verrucose, inner surface also rather closely verrucose | 
but with longer tubercles; peridial cells with a radially striate mar- 
gin, not easily torn apart, those of the inner layer often irregularly © 
compressed, walls thin, 2 to 4 » in thickness, lumen large; cells in | 
the upper portion of the peridium ovate, 15 to 20 by 22 to 42 yw, in © 
the lower portion ellipsoid to ovate, 16 to 20 by 40 to 60 p; sxcio- | 
spores very variable in size and shaeel subglobose, obovate, ellipsoid, — 
pyriform or even subclavate on some hosts, more or less acuminate © 
at the basal end, occasionally at both ends (Pl. I, figs. 1, 2, and 3), | | 
15 to 27 by 25 to 74 mw, average for 160 seclospores 21.6 ie 57.5 fy 3 
walls colorless, thicker at both ends than in the middle, 2 to 4 gp 
thick, rather ee verrucose with small irregular tubercles which — 
in narrow ellipsoid spores are often arranged in irregular almost paral- 
lel lines or with a ridgelike marking, which gives the surface a reticusl 
late appearance, no smooth spot present; cell contents of the zcio- | 
spores orange yellow when fresh. | 

Found on Pinus contorta Loud., P. divaricata (Ait.) Du Mont du | 
Cours., P. ponderosa Laws., P. pe scopulorum Sudw., P. 
pungens Michx., and Pinus sp. 

Uredinia aahic aren or hypophyllous,! scattered or densely gre- 
garious, on pallid areas, pustular, 125 to 200 » in diameter, dehiscent 
by a central opening or pore; peridium delicate; itedinioencea | 
broadly elliptical to globoid, 16 to 21 by 19 to 25 mw, average for 10 | 
spores 17.8 by 20 y, walls nearly colorless and sparsely but minutely | 
echinulate, 1.5 to 2 » thick. . 

Telial naan amphigenous or hypophyllous,* caulicolous, ovka 
drical, 80 to 115 y thick, about 1 mm. in length; teliospores oblong | 
to ey Wane obtuse to truncate at one or both ends, 12 to 16 by 28 
to 40 w, average for 10 spores 14 by 32.7 yw, walls smoeue nearly 
colorless. z| 

Found on Comandra pallida A. DC.,.C. umbellata (L.) Nutt., and~ | 
CO. richardsiana Fernald (?). | 

In the preceding description by the junior writer, the ae char- | 
acters (Peridermium) are taken from the specimens named in Table 
II on Pinus contorta, P. ponderosa, P. ponderosa scopulorum, and — | 
P. pungens. The aietental and telial characters (Cronartium) are | 


1 Amphigenous on Comandra pallida, hypophyllous on Comandra umbellata. 


Bul. 247, U. S. Dept. of Agriculture. PLATE |. 


A-CIOSPORES OF CRONARTIUM PYRIFORME AND A TWIQ OF PINUS CONTORTA. 


Fic. 1.—ciospores of Cronartium pyriforme, from the type specimen on Pinus sp. at Albany, 
N.Y. (Microphotograph.) Fic. 2.—/Hciospores of Cronarteum pyriforme from Pinus pun- 
gens, collected near Greenwood Furnace, Pa. (Microphotograph.) These closely resemble 
the type. Fra. 3.—Aciospores of Cronartium pyriforme from Pinus contorta, near Eldorado 
Springs, Colo., from the same tree as the type of Peridermiwm betheli (microphotograph), 
showing the variation in the shape of the spores on this pine from those of the type 
specimen in figure 1. Fie. 4.—A twig of Pinus contorta, showing the ecia and peridia of 
the eo Peridermium pyriforme (P. betheli) on a slightly swollen portion, (About natural 
size. 


Bul. 247, U. S. Dept. of Agriculture, 


INJURIES TO PINES PRODUCED BY CRONARTIUM PYRIFORME. 


Fic. 1.—A slight hypertrophy of the trunk of a small tree of Pinus pungens produced by the 
eecia of Cronartium pyriforme. (About one-third natural size.) Fie. 2.—Openings produced 
by the rupturing of the bark of Pinus pungens by the maturing of the ecia of Cronartium 
(Peridermium) pyriforme. (About one-third natural size.) Fic. 3.—A twig of Pinus contorta, 
showing a fusiform swelling produced by Cronartium (Peridermium) pyriforme on this species 
of tree. Similar fusiform swellings are produced by the fungus on Pinus ponderosa, (About 
one-half natural size.) 


A DISEASE OF PINES CAUSED BY CRONARTIUM PYRIFORME. 5 


taken from specimens of the fungus on leaves of Comandra umbel- 
lata obtained by inoculations with eciospores from Pinus pungens 
_ from Greenwood Furnace, Pa. 


e? INOCULATION EXPERIMENTS WITH THE FUNGUS. 


_ Table I gives complete inoculation data for this fungus on Comandra 
_ umbellata. Successful inoculations were made with eciospores from 
two hosts, Pinus ponderosa and Pinus pungens, collected from three 
4 widely Eaazated localities in the States of Washington, California, 
and Pennsylvania. In each instance control plants of the same 
‘species were used, and all remained free from infection. Unsuccessful 
inoculations were made with eciospores from Pinus contorta (Peri- 
dermium betheli) both during 1913 and 1914. In 1914 the failure to 
infect might have been due to the extreme high temperature of the 
_ greenhouse at the time the inoculation experiments were performed. 
_ However, the failure for two successive seasons to infect Comandra 
_ with the eciospores from Pinus contorta may indicate that the rust 
on this host is a different species from Peridermium pyriforme, since 
_ the shape and size of the eciospores (P. betheli; Pl. I, fig. 3) from 
_ Pinus contorta are different from those of the type specimen of this 
rust (PI. I, fig. 1). The writers, in the absence of proof from inocula- 
- tions, assume for the present that these morphological differences may 
be due to the host and therefore are not of sufficient importance to 
warrant classifying Peridermium bethelr as distinct from P. pyriforme. 


‘TaB_E I.—Resulis of inoculations with the xciospores of Cronartium pyriforme. 


a eee Results. 
_ cial host, serial num- Suciasinocalated E i iene 
per, and. locality. pecieés inoculated. | mocula-"| tre. t * Degree of ollector. 
; ; tion. | dinia. | Tella. | infection. 
Pinus contorta: 1913 
- 8500, Eldorado| Comandra umbellata..| June 18 |.......-].-...-.-.- No infection...} Bethel. 
: Springs, Colo. i) Pca 
a 8500,1 Eldorado Comptomia asplenifolig |». dO 2 oi )2- <a pien|acierensee-los0-s [2 Ca Pepe Do. 
a Springs, Colo. : 
a age Allenspark, Comandra umbellata..! June 27 |...-.---|--.-----.-f.2--. dG... seeseus Do. 
$ 
ae Oy Castilleja linearis......}... GOMER ee cee cl eciemae tole e oe C6 LY ate Do. 
Pinus ponderosa: 1914 1914 1914 
1g 1h om ime Comandra umbellata..| May 27 | June5| June 28 | Sparse?2....... Fisher. 
as 
LDDs a ee ee (GL Dy ehilades react a ae estan May 30] June9| July 4/|-..... On shee Do. 
nn oh Cal eye isis AO -mictansachesnees May 28] June6| July 5/]..... dO... .<e-24| Boyce: 
Pinus pungens: : 
15444, Greenwood |-..... OD es kh tiers oe May 29 | June 7| June 30| Very abun- | Hedgcock. 
3 Furnace, Pa. dant. 
| 15455, Greenwood !..... ClO ON aie huctera ss May 30 | Junel0| July 15 |...-.. COE ee ose Do. 
Furnace, Pa. : 
Og ae eer GAME ie SeeIe es as .ce ne doze) June ities dowsk. 225 GO. ar 42 Do. 
15462, Greenwood |...-.. GO 2 Seicatniwincicie ociex June 1 |-..do.-| July» 1 | Sparse. ...~.~. Du. 
Furnace, Pa. 
DUE ee eee Bee aides wah ue at June 2|Junei2| July 4) Abundant... Do. 
i ao ee eee CO enero soe Bas oss do....| Junel3} July 8 |...-. Gort. scene Do. 
‘ ee Le Seen Oe Re June's}. -do..| July 5}. Sparse.jo.c.25. Do 
Pinas contorta: 
“@ mf ee, Migora , |. :..% O62 + eriten tiga: OU ais 21 OS ae a No infection 4.. Do. 
— Colo. 
Toe Ribes longiflorum.....|..- COs See eile gah cme ieee Cowes eases Do 


17 ype of Peridermium betheli. 3 Telia immature. 
2 Sparse here means less than six sori. 4 Inoculation made in very hot weather. 


6 BULLETIN 247, U. S. DEPARTMENT OF AGRICULTURE. 


A study of Table II and of figures 1 and 2 of Plate I shows some 
very interesting facts. For instance, the shape and size of the spores 
from the type material (Pl. I, fig. 1) and those from Pinus pungens 
(Pl. I, fig. 2) are practically identical, since the range in size for 20 
spores of the type is 19 to 25.6 yu by 41.6 to 73.6 » with an average 


for 20 spores of 23.4 by 58.6, and for 20 spores from Pinus pungens 
the range is 19 to 25.6 » by 42 to 73.6 » with an average for 20 spores _ 


of 23.1 by 59.1 ». This close similarity in size and shape would 
indicate that the type may have been on Pinus pungens, but this 
does not seem probable if the type really came from Newfield, N. J., 
as Pinus pungens has not been reported from this locality, although 
Britton (4) reports it as abundant 1 mile east of Sergeantsville, in 
Hunterdon County. It is possible that sporadic or introduced 
specimens of Pinus pungens may have been growing near Newfield 
at the time the collection of the type specimen of Peridermium 
pyriforme was made. The alternate stage of the rust, Cronartium 
pyriforme, on Comandra umbellata was collected at Newfield, N. J., 
by Ells in August, 1879, and issued by him in North American 
Fungi under the number 1082. ‘This indicates that the type material 
of Peridermium pyriforme came from New Jersey. 


TaBLE II.— Measurements, shape, etc., of the xciospores of Cronartium pyriforme. 


Measurement (microns). 


ZEcial host, serial number, 


and locality. Acumination. 


Shape. 


Range in size. Average for 


20 spores. 
Pinus pungens: 
15462, Pat alias Fur- | 19 to 25.6 by 42 to | 23.1 by 59.1..| Obovate or pyri- | Often Lie long 
nace, 73.6. form to subcla- (Pl. I, fig. 2). 
vate or spatulate. 
Pinus sp 
Tae, Newfield, N. J. (?).| 19 to 25.6 by 41.6 | 23.4 by 58.6..] Obovate to pyri- | Often very long 
to 73.6. form or subcla- Pl. I, fig. 1). 
vate. 
Pinus ponderosa: 
15556, near Darby, Mont..| 19 to 25.6 by 38 to | 22.4 by 48.6.. Obovate to pyri- | Often not very pro- 
64. form or rarely nounced. 
ellipsoid. 
12467, Wenatchee, Wash.. en 25.6 by 38 to | 21.1 by 51.5.. Chow to pyri- Do. 
: orm 
12468, Rocky Gulch, Cal.. 708 4 Pe byu35 1<23:9 by 54:5... doses = eee Do. 
0 70.4. 
Pinus ponderosa scopulorum: 
12470, Crook National | 19 to 27 by 32 to 64.| 21.8 by 44.3..| Ellipsoid or obo- | Usually very short. 
Forest, Ariz. vate to pyriform. , 
Pinus contorta: 
15550, Eldora, Colo....... 16. to 25.6. by 25 to, | 18.1 by 40.2: .|.....do.. eee OePL TL, fe yay, ais 
45. 
el Eldorado Springs, | 15 to 26 by 25 to 48.| 20 by 43.....|..-.- do.- SvAseeeae Usually’ very tak 
olo. 


= 


The senior writer, during August, 1914, visited Newfield and several 


other localities in the same region. 


He found the same species of 


pine here that are known to occur in southern New Jersey and that 
probably were present at the time of the Ellis collection, viz, Pinus 
echinata, P. rgida, and P. wrginiana. None of these were fone by 
him to be diseased with the Peridermium of Cronartium pyriforme. 


ipa pile sian SACI te ott Tot apy 


Ba i en ey Se ae ae manta 


4 


A DISEASE OF PINES CAUSED BY CRONARTIUM PYRIFORME. 7 


Comandra umbellata observed in a number of these localities was also 
free from the rust. 
In 1914 the senior writer found Pinus pungens, P. rigida, and P. 


virginiana closely associated in-a mixed forest near Greenwood Fur- 


nace, Pa. In this instance Pinus pungens was attacked by Peri- 
dermium pyriforme so badly that in some places more than 50 per 
cent of the trees were killed, and although Comandra umbellata plants. 
_ bearing the telial form of ae rust were present in abundance, no pines 


] of either of the other species were diseased. This indicates that these 


_ two species of trees are immune and that neither can be the host for 


the type specimen that Ellis found at Newfield. Of the five species 
_ of pines known to be the ecial host of this fungus, not one is a strictly 


three-needle pine. All have either two or two to three needles in the 
leaf clusters. This makes it seem improbable that Pinus rigida was 
the host of the type material. Panus echinata is a two to three needle 
pine found in southern New Jersey, and this species may have been 
the host of Ellis’s type. 

The cultural work done by the writers with Peridermium pyriforme 
Peck proving it to be the ecial stage of Cronartium pyriforme (Peck) 
Hedge. and Long on species of Comandra completes the life history 
of all the caulicolous species of Peridermium as now recognized in the 
United States. There are four native and one introduced species and 


- each constitutes the ecial stage of a species of Cronartium: 


(1) Peridermium pyriforme, which is the ecial stage of Cronartium pyriforme. 
(2) Peridermium cerebrum Peck is the ecial stage of Cronartiwm cerebrum (Peck) 


_Hedgc. and Long on species of Quercus and Castanopsis. This is a well-recognized 
_ eastern species and, including its western form, Peridermiwm harknessti Moore, is the 
_ only native gall-forming Peridermium in the United States. P. harknessii on Pinus 
_ radiata Don is synonymous with Peridermium cerebrum, since it is associated with 


Cronartium cerebrum on Quercus agrifolia Née on the Monterey Peninsula in California. 


L The other forms of Peridermium harknessti may not belong here, and until cultural 
_ proof of their identity with P. cerebrum is obtained, the forms on Pinus ponderosa, 
_ Pinus contorta, and other western pines remote from species of Quercus and Cas- 
_tanopsis can only be doubtfully referred here. 


(3) Peridermium comptoniae (Arth.) Orton and Adams, a well-known eastern species, 


9 usually occurring on the pitch pine (Pinus rigida Mill.) in the eastern and north- 


eastern United States, but also attacking two to three needle species, is the ecial 


stage of Cronartiwm comptoniae Arth. which attacks Hs tla peregrina (L.) Coult. 


and Myrica gale L. 
(4) Peridermium filamentosum Peck on Pinus ponderosa and Pinus contorta is the 


~ ecial stage of Cronartium filamentosum (Peck) Hedgc., which attacks a number of 


species of Castilleja in the western United States over a wide region, ranging from the 


_ Rocky Mountains to the Pacific coast. Peridermiwm stalactiforme Arth. and Kern 

and Cronartiwm coleosporioides (Dietel and Holway) Arth. and Kern are synonymous 

_ with this species. 

(5) Peridermium strobi Kleb., an introduced species, is the ecial stage of Cronar- 

_ tiwm ribicola Fisch. de Waldh., which attacks many species of Ribes. In Europe this 
Peridermium attacks several species of white (5-needle) pine. In the United States 

it has been found on only one species, Pinus strobus L. 


8 BULLETIN 247, U. S. DEPARTMENT OF AGRICULTURE. 


For a number of years Prof. E. Bethel has collected from the leaves — 
of Ribes longiflorum at Denver, Boulder, and elsewhere in Colorado 
a species of Cronartium which is apparently not identical with the — 
European Cronartium ribicola. The senior writer collected abundant — 
specimens of the uredinial and telial forms of this rust both at Boulder — 
and Denver, Colo., in October, 1914. The telia of this Cronartium — 
are larger, more abundant, and much more conspicuous than those 
of the European species. Although the fungus has been epidemic 
for several years on the Chautauqua grounds near Boulder, two young 
white pines (Pinus strobus) on the grounds not far from the diseased 
Ribes were free from the disease. This species apparently is able to 
winter over on Ribes plants in the uredinial form. It may yet be 
found that the ecial form is a Peridermium on one of our native 
Pet DISTRIBUTION OF THE FUNGUS. 

DISTRIBUTION OF THE CIAL FORM. 


The ecial form of the fungus, Peridermium pyriforme, is widely — 
distributed in the United States, having been found in 10 States: 


——— 


a 
ee 


? 
=. 


Fig. 1.—Outline sketch map of the United States, showing the known distribution of Cronartium pyri- 
forme. Localities where collections of the different forms of the fungus have been made are indicated as 
follows: v, Aicial form on species of pines; 4, uredinial and telial forms on species of Comandra; X, all 
forms. 

Arizona, California, Colorado, Montana, New Jersey, Pennsylvania, 

South Dakota, Washington, Wisconsin, and Wyoming (fig. 1); and 

when a more careful search is made for the fungus, in the light of our 

present knowledge, it will no doubt be found to have a much more 


general distribution in this country. It has also been found in 


Alberta and British Columbia. 


1 Allspecimens cited except those marked with a star (+) have been examined by one of the writers. 


A DISEASE OF PINES CAUSED BY CRONARTIUM PYRIFORME, 9 


DISTRIBUTION IN THE DOMINION OF CANADA. 
_ Alberta.—On Pinus contorta (P. murrayana): * Devil’s Lake, 
Banff, by Holway (3, p. 127), in 1907. 
British Columbia.—On Pinus ponderosa: * Vernon, by Brittain, 
in 1913. 


DISTRIBUTION IN THE UNITED STATES. 
— New Jersey.—On Pinus sp.: (Type) Newfield, by Ellis (2040), in 
1882 (Herbarium New York State Museum). 
— Pennsylvania.—On Pinus pungens: Charteroak, by Orton and 
Adams, in 1913 (F. P.' 15129); Greenwood Furnace, by Hedgcock, 
in 1914 (F. P. 15444, 15455, and 15462); Petersburg, Huntingdon 
County, by Hedgcock, in 1914 (F. P. 15483). 
— Wisconsin.—On Pinus dwaricata: * Douglas County, by Davis. 
South Dakota.—On Pinus ponderosa scopulorum: * Rockerville, by 
White; Black Hills near Custer, by Hedgecock and Phillips (F. P. 
15826) and by Hedgcock (F. P. 15801), in 1914. 
~ Wyoming.—On Pinus contoria: Dubois, by C. E. Taylor, in 1914 
m. P.'15797). 

Colorado.—On Pinus contorta (P. murrayana): * Gatos (collector 
not given), in 1906 (3, p. 126-127); Eldorado Springs (F. P. 8500), 
type of Peridermium betheli, Lake Eldora (F. P. 8511), Allenspark 
(F. P. 8502 and 8514), Arrow (F. P. 8515 and 8494), by Bethel, in 
(1913; Eldora (F. P. 15550), by Bethel, in 1914. 
~ On Pinus ponderosa scopulorum: Monument, by Hedgecock, in 
1912; Allenspark, by Bethel, m 1913 (F. P. 8504, 8505, 8510, and 
8451). 

Montana.—On Pinus ponderosa: Darby, by Weir, in 1914 (F. P. 
15556). | 

Washington.—On Pinus ponderosa: Wenatchee, by D. F. Fisher, 
in 1914 (F. P. 12467). 

On Pinus sp.: * Seattle, by Bonser (3, p. 127), in 1906. 
~ California. —On Pinus ponderosa: Trinity National Forest, by 
Box, in 1912; Rocky Gulch, Siskiyou County, by Meinecke, in 1913; 
by Boyce, in 1914 (F. P. 12468); Mills Ranch, Goosenest Mountain, 
Siskiyou County, by Boyce, in 1914 (F. P. 15678 and 15680); Cas- 
tella, Shasta County; Weaverville and Brown Creek, Trinity County, 
by Boyce, in 1914. 

Arizona.—On Pinus ponderosa scopulorum: Crook National Forest, 
by Swift, in 1914 (F. P. 12470). 

DISTRIBUTION OF THE UREDINIAL AND TELIAL FORMS. 
 Cronartium pyriforme, representing both the uredinial and telial 
forms of the fungus, has been collected more frequently and over a 
greater range of terrritory than the ecial form. It has been found in 


1 Forest-Pathology Investigations number. — 


~ 93041°—Bull. 247—15 2 


a 
10 BULLETIN 247, U. S. DEPARTMENT OF AGRICULTURE. . 


Quebec and Ontario in the Dominion of Canada and in the United g 
States in the following States: California, Colorado, Dlinois, Massa- 


chusetts, Michigan, Missouri, Montana, Nebraska, New Jersey, New _ 


‘York, North Dakota, Ohio, Pennsylvania, South Dakota, Utah, _ 
Washington, Wisconsin, and Wyoming (fig. 1). . | 
DISTRIBUTION IN THE DOMINION OF CANADA,! j | 

Quebec.—On Comandra umbellata.A—Seven Islands, by C. B. Robin- — 
son (858, Plants of Quebec). 3 
Ontario.—On Comandra umbellata.2—London, by J. Dearness (2443, 


Sydow Uredineen and 3419, Fungi Gomataaa and Point Abino, 
by J. J. Davis (Herbarium New York Botanical Garden). 


DISTRIBUTION IN THE UNITED STATES. 


Vermont.—On Comandra umbellata: Between Essex Junction and — 


Burlington, by Hedgcock (F. P. 8539 and 8655); locality not given, — 


by A. J. Grout (Herbarium New York Botanical Garden). 3 
Massachusetts —On Comandra umbellata: Magnolia, by Seymour — 
and Earle (210-a and 210-b, Economic Fungi). | 
New York.—On Commadns umbellata: Syracuse (Ex. Herbarium — 
L. M. Underwood); Ithaca, by H. S. Jackson (1458, Flora North 
America); Mount Defiance, by Peck (Herbarium New York State ~ 
Museum). | 
New Jersey.—On Comandra umbellata: Newfield, by Ellis (1082, 
Eilis and Everhart, North American Fung’). : 
Pennsylvania.—On Comandra umbellata: Charteroak, Hunting- 
don County, by Orton, Adams, and Kirk (9, p. 25); Petersburg, 
Huntingdon County, by Hedgecock (F. P. 15637). Greenwood ~ 
Furnace, Huntingdon County, by Hedgecock (F. P. 15653, 15654, and 
15657). L 
Ohie—On Oomandra umbellata: Cleveland, by B. T. Galloway. 
Illinois —On. Comandra umbellata: Oregon, by M. B. Waite (85, 
134, 176, and 366). ; 
Missouri—On Comandra pallida: Emma, by C. H. Demetrio — 
(4310, Rabenhorst-Paczschke, Fungi Europei et Extra-Europei). __ 
Michigan.—On. Comandra umbellata: Ann Arbor, by Holway (504, — 
North American Uredinales); Ann Arbor, by F. L. Seribner; Ros- — 
common, P. Spaulding (F. P. 15681). g 
Wisconsin.—On Comandra umbellata: Racine, by J. J. Davis; The — 
Dells, by Underwood (Herbarium New York Botanical Garden). € 
Nebraska.—On Comandra pallida: Dismal River, by Webber (784, — 
Fungi Nebraskenses); Hat Creek basin, by Webber (776, che: z 
Nebraskenses); Lincoln, by R. J. Pool (F. P. 17045). | 


3 All specimens here listed are in the mycological collections of the United States Department of Agricul- 
ture unless otherwise noted. q 
2 These species probably should be Comandra richardsiana Fernald, since the collections were made in —_ § 
sange of C. richardsiana and out of the range of C. umbellata as now recognized. zy 


A DISEASE OF PINES CAUSED BY CRONARTIUM PYRIFORME., 11 


 Wyoming.—On Comandra pallida: Big Horn Mountains, by Wil- 
- liams and Griffiths (298-a, West American Fungi); Bear Lodge 
Mountains, by Griffiths and Carter (298, West American Fungi); 
- Centennial, by E. T. and E. Bartholomew (3705, Fungi Columbiani) ; 
near Medicine Bow River, by A. Nelson (1257, Herbartum University 
of Wyoming). 

~ South Dakota.—On Comandra pallida: Iroquois, by F. A. Wiliams 
— (1914, Fungi Columbiani); Black Hills, near Custer, by Hedgecock 

and Phillips (F. P. 15827 and 15828). 

North Dakota.—On Comandra pallida: Beaver ae by: 3. i. 
_ Brenckle (78, Fungi Dakotenses). 

Colorado.—On Comandra pallida: Boulder, by F. EK. and E. §. 
Clements (542, Cryptogamex Formationum Coloradensium); south of 
_ Yuma, by H. L. Shantz, U. S. Dept. Agr. Plant-Disease Survey; 
- Short Creek, Custer County, by T. D. A. Cockerell (99 and 104, Ellis 
- Collection in Herbarium New York Botanical Garden); Soldier 
_ Canyon, by J. H. Cowen (168, Ellis Collection); La Veta, by C. A. 
Crandall (283, Ellis Collection); Pagosa Peak, by C. F. Baker (22, 
_ Plants of Southern Colorado); also by F. S. Earle (120, Herbarium 
New York Botanical Garden); Sangre de Cristo Mountains near 

Westcliffe, by Hedgecock (F. P. 8082); Steamboat Springs, by Hedg- 
cock (F. P. 3873 and 3889); Monument, by Hedgecock (F. P. 3792, 
3839, 15948, and 15950); Eebaee Lake, by Hedgcock and Bethel 
(Ff. P. 3794 anil 3819); Boulder, by ise dueackt (F. P. 15885); Golden, 
_ by Hedgecock (F. P. 15888); Palwer Lake, by Hedgcock (F. P. 15907 
and 15948); Monument Nursery, by Hedgcock and Pierce (F. P. 
15950). ; 

Utah.—On Comandra pallida: Locality not given, by M. E. Jones 
(Herbarium New York Botanical Garden). 

Montana.—On Comandra pallida: Helena, by F. D. a ee 
Sandcoulee, by F. D. Kelsey (2419, Ellis eee Everhart, North 
American Fungi); Sandcoulee (80, Montana Flora) and Helens (61, 
Parasitic Fungi Montana), by F. W. Anderson; Missoula, by Hedg- 
cock and Kirkwood (F. P. 8021). 

Washington.—On Comandra pallida: West Klickitat paw ta by 
W. W. Suksdorf (176, Flora of Washington). 

——s Californa.—On Comandra umbellata: Shasta Springs, by W. C. 
Blasdale (6 North American Uredinales), by M. A. Howe (101, Fungi 
_ California), Herbarium New York Botanical Gardens; Mills Ranch, 
_ Siskiyou County, by Boyce (F. P. 15796); Integral Mine, Bheata 
- County, by Boyce; Rocky Gulch, Siskiyou County, by Meinecke; 
_ Weaverville and Brown Creek, Trinity County, by Boyce; Goosenest 
q Mountain, Siskiyou County, by Boyce and Rider. 


12 BULLETIN 247, U. S. DEPARTMENT OF AGRICULTURE. 


DISSEMINATION OF THE FUNGUS. 


Cronartium pyriforme is disseminated by means of its three spore 
forms—viz., eciospores, urediniospores, and teliospores—each form 


playing an important réle in maintaining the succession of generations 


between pine trees and Comandra plants. The process of infection 
with this species of rust does not differ materially from that of the 
white-pine blister rust (12). 

The ecia on the table mountain pine (Pinus pungens) in Pennsyl- 
vania mature from the middle of May to the latter part of June. 
Farther north on the jack pine (Pinus divaricata) they bear their 
spores somewhat later in the season. On the lodgepole pine (Pinus 
contorta) and the western yellow pine (Pinus ponderosa) from Colorado 
to Wyoming, the period of maturity is from the middle of June to the 
middle of July. In each region they develop earlier on slopes of 
southern exposure and at lower altitudes. 

The seciospores are discharged in great abundance for a day or two 
and with lessened abundance for about a week longer. They infect 
any Comandra plants with which they come in contact. The leaves 


are most commonly infected, but occasionally the stems and floral 


parts are attacked. The infection near diseased pine is usually very 
abundant, decreasing rapidly as the distance increases. Anabundant ~ 
infection from eciospores has not been noted for more than 200 feet — 
from the ecial center, when it is located on small pines. When large ~ 
pines are diseased in the upper limbs, the distance that the zciospores 
are blown is greatly increased, and the zone of infection is therefore — 


extended very much, and on mountain slopes may reach the distance _ 


of nearly 1,000 feet. This inoculation of Comandra plants by 
eeciospores may well be designated as a primary infection, and that by _ 
urediniospores, described in the following paragraph, as a secondary ~ 
infection. . 

In 8 to 10 days from the time of inoculation by exciospores the 
uredinia appear on the leaves of the infected Comandra plants and 
urediniospores begin to be produced. These are blown about by ~ 
winds and inoculate other Comandra plants. This secondary infec- 
tion greatly extends the area of diseased plants. A second crop of 
uredinia develops in from 8 to 10 days from these secondary infections. 
This process continues throughout the growing season. It is possible 
that as many as six or more generations of uredinia may be thus pro- 


duced in one season, and the fungus may spread several miles in this + 


manner. It is by this method of infection that the fungus spreads 
the greatest distance in nature, which explains why the form of fungus 
on the Comandra plants is more common than on the form of pines. 

In about 15 days the telial columns develop from the uredinial sori — 
on the Comandra plants. As each column grows older it gradually 
elongates, and the development of teliospores progresses outward — 


A DISEASE OF PINES CAUSED BY CRONARTIUM PYRIFORME. 13 


along the column with its growth. The period of teliospore formation 
for each telium is from one to two weeks. The teliospores germinate 
_ in situ as fast as they mature, without being detached from the telial 
columns. As each teliospore germinates it develops a basidium, 
_ which when typical bears four sporidia. The sporidia borne on each 
_ basidium, however, are usually less than four. The sporidia become 
_ detached as soon as mature and are carried away by even the slightest 
breeze. They readily infect the younger part of pine trees, thus 
- completing the life cycle of the fungus. From observation it appears 
probable that germinating sporidia usually gain entrance into the 
tissues of the pines through wounds or in wound callus where young 
cells are exposed. Inoculations with another species, Cronartium 
cerebrum, on pine trees (Pinus virginiana) without wounds have failed, 
while at the same time, other conditions being similar, they were 
successful in wounds. 

Since each generation of uredinia on Comandra plants is followed 
within a few days by one of the telia, there is a continual produc- 
tion of sporidia from the time the telia first appear till the end 
of the growing season. This greatly extends the period of pos- 

sible infection for pines, a period which must be from two to four 
months, depending upon the length of the growing season in pines, 
which varies not only at different altitudes and in different latitudes, 
but also from season to season. 
_ Itis highly probable that the various spore forms of this fungus, 
especially the eciospores from the pines, may be carried about on 
the bodies of birds and of the smaller animals. In this manner they 
could be carried even to greater distances than is possible by wind 
dissemination. 

If young pines in nurseries should become infected, the danger 
of a much wider dissemination of the fungus than has es taken 
place in nature is at once possible, with man as the agent. Under 
conditions such as occur in many localities both in the eastern and the 
western United States it would be easily possible for the pines in 
nurseries to become badly infected, owing to the abundance of Coman- 
dra plants in the vicinity. 


EFFECT OF THE FUNGUS ON ITS HOST PLANTS. 


EFFECT OF THE ASCIAL FORM ON PINES. 


_ The immediate effect of the «cial form, Peridermium pyriforme, 

varies in different species of pines and on the same species under 
di fierent conditions. When young lodgepole pines or western yellow 
‘pines are attacked, either on the trunk or limbs, there commonly 
develops a slightly. swollen area in the region of ho infection. If 
the infected area encircles the trunk, as it usually does, a spindle- 
Shaped or fusiform swelling may result (Pl. II, fig. 3), which varies 


coed 


iF 
eer 


14 BULLETIN 247, U. S. DEPARTMENT OF AGRICULTURE. 


from an inch to more than a foot in length. In case of Pinus pungens 
(Pl. II, figs. 1 and 2), fusiform swellings are not so common as in 
case of Pinus contorta and Pinus ponderosa. Swelling is commonly 
not very evident in very young trees of any of these three species. © 
The bark layers are usually thickened in the portions where the rust _ 
mycelium is present. So far as can be ascertained from field observa- 
tions the «cia may not appear until three or more years after infection | 
takes place. , | 

The development of the peridia at the maturity of the ecia rup- 
tures the bark of the diseased areas, forming numerous openings 
(Pl. II, fig. 2) which reach to the inner layers of the cambium. Asa 
result the death of the cambium layer may take place, due apparently 
to excessive evaporation of water through the lesions. The part of © 
the tree attacked usually is either girdled and killed outright or itis 
partially girdled and a canker is formed. Young pines are very | 
commonly girdled and killed during the same season the ecia are 
produced. In its effect on pines, Peridermium pyriforme must be 
classed with P. strobs and: P. jilamentosum and be ranked as one 
of the most destructive species of Peridermium in North America. — 

In a region adjacent to Greenwood Furnace, Huntingdon County, © 


Pa., the senior writer, during June, 1914, took notes on the number 
and condition of pines (Pinus pungens) diseased with Peridermium 


pyriforme. Again, in autumn, the condition of the same trees was | 
noted, and it was found that of 50 diseased pines upon which the 
zecia had been found in June, 29 (58 per cent) were dead from the 
girdling effect of the fungus. 

These had apparently died shortly after the «cia fruited, as dead 
leaves were still clinging to the branches of the trees. The pines ex- 
amined were small, varying in height from 4 to 10 feet, and in diam- 
eter at the ground from 1 to 4 inches. A similar effect was noted 
during the autumn of 1914 on a smaller number of young pines 
(Pinus ponderosa) in the Black Hills near Custer, S. Dak. 1 

J. S. Boyce, of the Office of Investigations in Forest Pathology, has — 
reported this fungus on the yellow pine (Pinus ponderosa) in Klamath, — 
Shasta, and Trinity National Forests in California.t This report — 
states that in the Klamath National Forest— 4 


The parasite produced spindle-shaped swellings at the point of infection on the 
yellow pine, usually on the main stem but occasionally on the branches. These — | 
swellings varied from 2 inches to a foot in length. 

The fungus on yellow pine undoubtedly kills that portion of the main stem or branch 
of the tree above the point of infection. A number of small trees were found to have — 
been killed. Each of these bore one or more spindle-shaped swellings on the stem. 
A volunteer (shoot) had then appeared while a new infection had occurred just 
below the point where the volunteer joined the main stem. A repeated killing of - 
this kind causes a strikingly deformed tree. gq 


— 


~~ 


1 Boyce, J.S. Notes on Cronartium pyriforme. Unpublished report submitted December 7, 1914. 


A DISEASE OF PINES CAUSED BY CRONARTIUM PYRIFORME. 15 


The largest infected tree found was 12 feet high and 3 inches in diameter at breast 
height, approximately 22 years old, with the infection occurring 5 feet from the ground. 
In another area here 10 saplings killed by the fungus, with only one living uninfected 
tree, were found. 

One diseased area of Pinus ponderosa at Mills Ranch on the north 
slope of Goosenest Mountain in the Klamath National Forest was 
described by Boyce, which contained at least a hundred acres. The 
largest tree diseased by the fungus in this area was 8 inches in diame- 
ter at breast height. Spindle-shaped swellings were common, but 
more especially on the younger, smaller trees. The girdling effect 
and death of the host tree in the parts above the point of infection 
were very much in evidence in this area. Small trees apparently 
were girdled and killed much sooner than older trees. Wounds caused 
by some gnawing animal, presumably the porcupine, were common 
on trees in areas where the fungous disease occurred. In one of the 
diseased portions of the forest a sample plat was established by 
Boyce and a count of the healthy, infected, dead, and dying trees 
of Pinus ponderosa was made. The result was as follows: Out of 314 
trees in the plat, 153 (48.7 per cent) were apparently healthy, 52 
(16.5 per cent) were plainly diseased by the fungus, 3 (0.9 per cent) 
were dying, and 106 (33.7 per cent) were dead from the effects of the 
fungus. In the words of the report: 

Over 50 per cent of the total number of trees of the sample plat had been infected, 
and nearly two-thirds of the total number infected had already been killed. There is, 
of course, a possibility that the death of some of these might have resulted from other | 


causes, but only those trees were included which I was certain in my mind had been 
killed by the fungus. 

Boyce’s data corroborate those taken by the senior writer both in 
Pennsylvania and South Dakota. 

Reporting concerning an area of diseased Pinus ponderosa along 
Browns Creek in Trinity National Forest, Boyce says: 

There were many dead trees, undoubtedly killed by the fungus, with spindle-shaped 
swellings on the main stems. On living infected trees the ecia were sporulating 
(June 27, 1914), but not very abundantly, not to be compared with the sporulation 
found at Rocky Gulch on May 20. One infected sapling was found in which the 
major portion of the bark had been destroyed either by wood rats or porcupines. 

Where the trunk is not girdled, cankers or catfaces are occasionally 
formed by the death of a portion of the cambium. In such cases 
_ the continued presence of the fungus in the live tissues beyond the 

dead area stimulates their growth, and the fungus may fruit a number 
_ of times before the tree is killed. Catfaces on the lodgepole pine 
' (Pinus contorta) and on the western yellow pine (Pinus ponderosa), 
_ however, are more commonly produced by another species of rust, 
_ Peridermium harknessii. 
_  Peridermium pyriforme, when it infects the trunk of a pine tree, 
_ May spread from the trunk to such limbs as spring from a point near 


16 BULLETIN 247, U. 8S. DEPARTMENT OF AGRICULTURE. 


the center of infection or, vice versa, may spread from the point of 
infection on a limb to that part of the trunk adjacent to the diseased 
area on the limb. Jn this it resembles P. filamentosum (5) and the 
fusiform type of P. cerebrum (P. fusiforme) (7, p. 248). Such im- 
stances in the case of both P. pyriforme and P. filamentosum on Pinus 
ponderosa have been observed by the senior writer in Colorado and 
Wyoming and noted by Spaulding (11, p. 28, 34) in the case of Peri- 
dermium strobi on white pines in the northeastern United States. 


EFFECT OF THE UREDINIAL AND TELIAL FORMS ON COMANDRA PLANTS. 


The effect of the uredinial and telial forms of the fungus, Cronartium 
pyriforme, on Comandra plants can not be separated into two distinct 


sets of symptoms, since the two forms are produced on the same ~ | 


area of tissue, the one following the other in a few days. Both the 
uredinia or the telia may occur on either surface of the leaves, as 
well as on the younger portions of the stems, and occasionally on the 
floral parts.1_ In badly infected plants there is a decided shortening 
of both the stems and the leaves in their growth, so much so as to 
change the entire aspect of the plants. This is usually accompanied 
by a slight chlorosis of the leaves. Where the infection is slight, the 
diseased spots on the leaves are usually a lighter green color than the 
uninfected portions. Late in the growing season the reverse colora- 
tion sometimes takes place, and the chlorophyll is retained longest 
in light-green areas in the leaves where the mycelium of the fungus 
is found, even after the remainder of the leaf has become yellow from 
fall coloration. 

In badly infected Comandra plants defoliation takes place prema- 
turely; that is, before drought, frost, or cold weather bring it about. 
No data have been obtained as to the final effect of the rust on 
Comandra plants. The effect, however, is decidedly stunting, and 
plants infected badly for several seasons would undoubtedly be killed. 


ERADICATION AND CONTROL OF THE FUNGUS. 


One of the most serious facts in connection with the prevalence of 
Peridermaum pyriforme in some portions of the western United States 
is the danger of introducing it into localities now free from it through 
the shipment of trees in the work of artificial reforestation. For this 
purpose nursery stock is often shipped long distances. The forest 
nursery if situated in mountain regions 1s apt to be in a locality where 
Comandra plants are common. Since these serve as host plants for 
both the uredinial and telial forms of the fungus, their presence may 
lead directly to the infection of the young pines in the nursery and 
indirectly to the infection of localities hitherto free from the disease. 


1In Comandra pallida this is the case. In Comandra wmbellata the uredinia and telia are found uniformly 
on the under surface of the leaves. 


A DISEASE OF PINES CAUSED BY CRONARTIUM PYRIFORME. 17 


If it were possible to distinguish all of the diseased trees at the time 
of planting, it would be an easy matter to discard them and thus 
prevent the further spread of the disease. Such, however, is not the 
case, since the disease may not become evident until three or four 
years after the young trees are infected and until after they are planted 
in the forest. This being the case, other means for the control of the 
_ disease must be adopted. The most feasible plan to prevent further 

_ infection in the nursery and the subsequent dissemination of the 
_ disease through infected nursery stock appears to be the elimination 
of all Comandra plants in the vicinity of the nursery. 

In order to protect the nursery from infection whenever the dis- 
ease is present in adjacent forests, all diseased pines that can be 
found within a radius of at least half a mile from the nursery should 
be cut down. These can be selected most easily by a person familar 
with the fungus, at the time the ecia mature in the pines. As pre- 
viously stated, this period varies from the middle of May till in 
August, depending upon both the latitude and the altitude of the 
locality. This cutting-out process should be repeated each year until 
no more diseased trees can be found in the proposed neutral zone. 

_ The elimination of all diseased pines will not suffice, however, 
absolutely to control the disease in the nursery when Comandra plants 
are in the vicinity, since it is quite certain that the fungus can spread 
by the urediniospores from one Comandra plant to another for long 
distances in one season. By this means the disease could be carried 
from diseased pines outside of the neutral zone or belt of removal to 
the young pines in the nursery. To protect the nursery against infec- 
tion from this fungus all Comandra plants within 1,000 feet of the 
_ outer boundaries of the nursery should be removed by digging them 
out. 

Comandra plants are herbaceous perennials and spread primarily 
_ by means of seeds and secondarily by means of underground runners. 
The secondary method is the more common. The seeds, being 
edible, are much liked by birds and rodents, and it is possible that 
_ they may be carried by these animals to a considerable distance from 
the original place of growth, thus starting new plant colonies. The 
_ eradication of Comandra plant colonies will be difficult, owing to the 
_ numerous underground runners, any of which are liable to be broken 
_ off and left in the ground to start new plants. It will no doubt be 
_ necessary to dig up the plants repeatedly before they can be com- 
_ pletely eradicated. All species of Comandra are parasitic and derive 
part of their food supply from other plants by a direct attachment 
_ of the smaller side roots of Comandra to the roots of the host plants. 
_ It is not yet known how many species of plants are thus parasitized, 
_ but several widely different species are attacked. Species of Vac- 


¢ 


18 BULLETIN 247, U. S. DEPARTMENT OF AGRICULTURE. 


cinium are commonly parasitized. This wid bec is now bemg in- 
vestigated by the writers. 

The recommendations here given are based on observations made 
in forests by the senior writer and not on actual experiments. An 
attempt to control this disease as recommended here has been 
planned and will probably be carried out in 1915. Until it is certain 
that the neighborhood of a nursery is free from this fungus, ship- 
ment of stock to uninfected forests should be avoided. 

The spraying of pines with Bordeaux mixture or other fungicides 
for the prevention of infection by Cronartwum pyriforme can not be 
recommended until it is known that this method is effectual in con- 
trolling the disease. 

The spraying of Comandra plants with a poisonous substance to 
kill the foliage and tender shoots at the time they might be infected 
from the ecial form of the fungus on pines should prevent the imme- 
diate spread of the disease to the pines in adjacent nurseries. This 
spraying should be done as soon as the leaves of the Comandra plants 
are fully developed and before the plants bloom. This would prob- 
ably be from the latter part of May to the middle of July, depending 
on the altitude and the latitude of the locality. Should the Coman- 
dra plants send forth new growth later in the season it might be 
necessary to spray a second time. Spraying should be repeated each 
year as long as any Comandra plants remain alive. Where young 
pines are present, this method could not be used without killing them, 
and the uprooting of the Comandra plants is recommended for such 
areas. 

Mr. H. R. Cox, Agriculturist of the Office of Farm Management, 
Bureau of Plant ire has prepared a circular letter giving direc- 
tions for the use of plant poisons in killing vegetation. This circular 
follows, more complete directions being obtainable from the office 
mentioned upon request: 

For several years this office has been making tests of various chemical plant poisons 
for killing all vegetation in such situations as driveways, pathways, tennis courts, 
railroad rights of way, and similar places. It appears that of the substances there are 
three that are better than any of the rest, namely, arsenite of soda, common salt, and 
some form of petroleum. The best one of these for each case will depend upon condi- 
tions. It seems to be more economical usually to make a number of comparatively 
light applications for the purpose primarily of killing the foliage rather than one heavy 
one to affect the roots as well as the tops. 

In the case of most kinds of vegetation excepting the grasses, and especially for 
vegetation of a broad-leafed character, arsenite of soda is highly effective. The com- 
mercial grade may be obtained at about 25 cents per pound from some of the wholesale 
chemists. If large areas are to be treated, it can be made at home more cheaply by 
boiling 1 pound of white arsenic and 2 pounds of sal soda in a gallon of water until 
a stock solution is formed. From 10 to 20 pounds of the commercial arsenite of 
soda or from 7 to 14 pounds of the white arsenic in the home-mixed formula, either one 
diluted to make from 50 to 100 gallons of solution, is sufficient to kill most of the foliage 
on | acre. 


A DISEASE OF PINES CAUSED BY CRONARTIUM PYRIFORME. 19 


Common salt may be applied dry, provided it is fine grained and is scattered very 
uniformly. Salt may be applied more uniformly, however, if it is made into a satu- 
rated solution (1 pound to 14 quarts of water). The latter is usually the most satis- 
factory form. It should be used at the rate of from 3 to 5 tons per acre, depending 
upon the character and rankness of the vegetation. 

Of the petroleum products, fuel oil is about the most satisfactory, although this is 

sometimes difficult to obtain, and then only in barrel or tank-car lots. Near the oil 
fields, crude oil as it comes from the well can be obtained cheaply and is quite satis- 
factory. The petroleum products should be applied at the rate of from 300 to 400 
gallons per acre. If small areas are to be treated, so that the matter of expense is of 
little consideration, kerosene may be used. The petroleum products seem to be the 
most effective of all when applied to narrow-leafed vegetation, such as grass; salt 
seems to be the next in effectiveness on such plats, and arsenic third. 
_ A spraying outfit is best for applying liquid material, excepting the salt brine, with 
which a sprinkling can or sprinkler will do faster work. The petroleum products are 
very hard on the rubber parts of spraying outfits, but it is necessary to use a sprayer 
in that connection on account of economy of application; with very small areas where 
economy is not to be considered the oils can be applied through a sprinkling can. 


_ In the forest under our present conditions and market values it 
is not best to advise methods of elimination so expensive as have 
been given for the protection of nurseries. In badly infected areas 
of young forest trees, all diseased trees should be cut out whenever 
possible. This often can be done by the forest officer without very 
great expense, owing to the small size of the trees. In lumbering, 
trees diseased with catfaces or cankers should not be left for seed 
trees, as their vitality has been lowered and they will not produce 
as good a crop of seed as more healthy trees, and it is also highly 
probable that the viability of the seed produced by such trees is 
lower than that produced by more healthy trees. Again, trees with 
such cankers are often capable of producing eciospores around the 
border of the cankers and if allowed to remain for seed trees would 
become centers of infection for the younger generations of trees in 
the new forest. 


20 BULLETIN 247, U. S. DEPARTMENT OF aoe i 


LITERATURE CITED. 


(1) Artuur, J. C., and Kern, F. D. 
1906. North American species of Peridermium. In Bul. Torrey 
Club, v. 33, no. 8, p. 403-438. 


(2) ae 
1913. The rediscovery = Peridermium pyriforme Peck. In Science, 7 
n. s. v. 38, no. 974, p. 311-312. . 


(3) : ay? 
1914. North American species of Peridermium on pine. Jn Mycologia, 

. v. 6, no. 3, p. 109-138. segs 

(4) Brirron, N. L. 
1889. Catalogue of plants found in New Jersey. Jn Geol. Suite IN, ; J 3 

Final Rpt., v. 2, pt. 1, p. 27-642. 


(5) Hepecock, G. G. i 
1913, Notes on some western Uredinez which attack forest trees. Il 

In Phytopathology, v. 3, no. 1, p. 15-17. % 

and Lone, W. H. ‘7 
1913. An undescribed species of Peridermium from Coser In Phyto- | 
pathology, v. 3, no. 4, p. 251-252. an 


(6) 


uy 


(7) 


1914. Identity of Peridermium fusiforme with Peridermium cerebrum, 
In Jour. Agr. Research, v. 2, no. 3, p. 247-249, pl. 11. 


(8) ve 
1914. The Alternate Stage of Povacentuae Pyriforme. 3p. Washington, | 

D. ©. Privately printed. a 
(9) Orton, C. R., and Apams, J. F. 
1914. Notes on Peridermium from Pennsylvania. Jn Phytopathology, 
v. 4, no. 1, p. 23-26, pl. 3. oe 


s 


(10) Prox, C. H. 
1875. New fungi from New Jersey. Jn Bul. Torrey Bot. Club, v. 6, no. 2, 
p. 138-14. 

(11) SpaAuLpING, PERLEY. 


1911. The blister rust of white pine. U.S. Dept. Agr., Bureau of Pla 

Industry Bul. 206, 88 p., 5 fig., 2 pl. (1 col.). 

(12) Tusrur, CARL VON. a 
1914. Bekimpfung der Ribes-bewohnenden Generation des Weymouth hs- 
kiefernblasenrostes. In Naturw. Ztschr. Forst- u. Land wv. 

Jahrg. 12, Heft 3, p. 137-189. 


WASHINGTON : GOVERNMENT PRINTING OFF 


UNITED STATES DEPARTMENT OF AGRICULTURE 


z)} 
Contribution from the Bureau of Plant Industry 
WM. A. TAYLOR, Chief 


Washington, D. C. PROFESSIONAL PAPER - January 20, 1916 


LARCH MISTLETOE: SOME ECONOMIC CONSIDER- 
ATIONS OF ITS INJURIOUS EFFECTS.’ 


By JAMES R. WEIR, 
Forest Pathologist, Office of Investigations in Forest Pathology. 


CONTENTS. 
Page Page 
(nA cehh G00) 0) os Se 1 | The effects of mistletoe on its host_- a 
(hes lane mastietoe.—- =. 3 | Effect of mistletoe burls on the mer- - 
ier torediet = tee ee 3 | chantability of Starch treese2222 =~ 22 
Physical and climatic features of-the Menptod “of con tigh..-0 = sek 23 
eC rIOn ConelusTons=_2. 25>. Stee eens 24 
_ Fungous enemies of the larch______ iad 
INTRODUCTION. 


During the past four years, in connection with other pathological 
probleras in the forest, the writer has made an extensive survey of 
the damage to forest growth by some of the mistletoes of coniferous 
trees. These parasites are very widely distributed in the forest 
regions of the Northwest, and occur in such abundance in many 
localities as to assume a very serious aspect in relation to many 
forest problems. The extent and nature of the injury done vary 
greatly with the forest type, the topography, and, in some respects, 
with the climate. This is well shown in the regions in which investi- 
- gations are now being conducted. In the dense part of many forest 
regions, as in the vicinity of the great lakes of Idaho, mistletoe does 
but little damage. However, in the more open stands bordering on 
the lakes or along the edge of the valleys of the Priest and Pend 
Oreille Rivers mistletoe occurs so abundantly on the various conifers 
as to interfere seriously with the development of some of the more 


7 


valuable timber trees. About the shores of Lake Coeur d’Alene, 


1The writer wishes to express his thanks to Mr. J. F. Pernot, without whose assistance 
the analysis of the trees would have been difficult, and to Mr. HE. BH. Hubert for assistance 
n the tabulations. 


8521°—Bull. 317—16——1 


2 BULLETIN 317, U. S. DEPARTMENT OF AGRICULTURE. 


along the Spokane River Valley, and extending to the south into 
the Blue Mountains of Washington and Oregon the mistletoes are 
very abundant, especially on lodgepole pine (Pinus contorta), yellow 
pine (Pinus ponderosa), western larch (Larix occidentalis), and 
Douglas fir (Pseudotsuga taxifolia). In many localities the trees 
rapidly yield to the suppressing effects of these parasites, causing 
an open, ragged growth of the crowns, with the production of many 
brooms. The prevalence of a particular species of mistletoe varies 
greatly in the same general region. To illustrate: Along the hills 
fronting on the Pend Oreille River, Idaho, the lodgepole and yellow — 
pine stands are heavily infected. Passing up the Priest River Valley, 
another mistletoe species appears, working considerable injury to the 
larch, whereas the same tree, wherever it occurs along the Pend 
Oreille River, is seldom infected. The yellow pine farther up in 
the Priest River Valley is not seriously attacked. In the Granite 


Creek drainage area and beyond the mountains to Sullivan Lake, in — 


the Metaline Falls region of Washington, the larch is again very 
seriously infected, whereas this mistletoe seldom occurs on the divide 
between these points. The western hemlock (7'suga heterophylla) — 


in the forests of northern Idaho is practically free from mistletoe, — 


as far as the observations have been carried. In a few of the more 
open valleys several collections of mistletoe have been made from this 
tree. At many points in Washington and British Columbia where 
the writer has had an opportunity to collect, the mistletoe on the 
hemlock seems more abundant. Numerous collections of mistletoes — 
are at hand from many of the forests of southern Montana, and — 
likewise from the northern part of that State and from central Idaho. 
A trip through Oregon, Washington, and British Columbia during 
1913 yielded much information on the occurrence of mistletoes in — 
those localities, so that it will soon be possible, with the additional 
data now (1915) being collected, to give a fairly detailed statement of 
the range of these parasites in the principal forest regions = the 
Northwest. 

In order to obtain reliable figures on the damage to forest growth 
by these plants, special studies of a directly practical nature are now — 
being conducted in several of the most important forests of the 
regions indicated. It is believed that the results from these studies — 
will be applicable to all the forest areas of the Northwest where 
trees of the same species are found infected by the same mistletoe. 
At the same time, work of an experimental nature, both in the field © 
and in the laboratory, is adding to our knowledge of these parasites. 
This work is being continued, as having a practical bearing on the © 
mistletoe problem, and will be reported upon as time and occasion 
permit, 


LARCH MISTLETOE. 8 


THE LARCH MISTLETOE. 


* 
- 


- This bulletin deals in the main with the immediate practical results 
of an investigation of the injurious effects of the larch mistletoe on its 
host in the Blue Mountain region of Oregon and serves to introduce 
one of a series of studies on the mistletoes of coniferous trees in 
- general. The larch mistletoe (fig. 1), originally named Razoumof- 
skya douglasii laricis by Piper’ and given as a subspecies of the 
Douglas-fir mistletoe, has recently been raised by the same writer?” 
tothe rank of a full species under the following name and description : 
Razoumofskya laricis Piper. Pistillate plants olivaceous, clustered, 5-8 em. 
tong, branched; joints 1.5-2 mm. thick, sharply 4 angled; staminate swollen, 
yellow, the flowers in short spikes; lobes ovate, acute; fruit oblong, acutish, 
bluish, 4 mm. long. Common on Larix occidentalis. 
The investigation 
was begun in the Whit- 
man National Forest, 
Oreg. For some time 
the general and grad- 
ual deterioration of the 
western larch had been 
reported as occurring 
throughout the entire 
Blue Mountain region. 
‘The writer was not 
aware of the great 
prevalence of the larch 
mistletoe in this region 
until his visit there 
‘during the early 
spring of 1913, From 
a preliminary survey It, Wi¢.41—Staminate plants of Razoumofskya laricis. Note 
oon developed that the hypertrophy of the branch. 
the primary cause of the deterioration of the larch resulted from the 
suppressing effects of mistletoe. A probable secondary factor on 
some of the more exposed sites seemed to be certain climatic influences 
unfavorable to the host but promoting the better development and 
spread of the parasite. 


THE FOREST. 


art 
_ The Blue Mountains, in which further studies of the mistletoes are 
in progress, are well covered with forests. The yellow pine pre- 


4 Piper, C. V., and Beattie, R. K. Flora of Southeastern Washington and Adjacent 
Idaho, p. 80. Lancaster, Pa., 1914. 
a 


Ay, 
Bs 0% 
ve 


a 


4. BULLETIN 317, U. S. DEPARTMENT. OF AGRICULTURE. 


dominates as the principal tree on all the drier slopes and bench | 


lands. This gives an open character to the forest and is of some 
significance as regards the growth of mistletoe on the larch wherever 


this tree is associated with the yellow pine. On the lower eleva- _ 


tions the yellow pine often occurs in pure parklike stands, with a 
ground cover quite characteristic of the typical yellow-pine forma- 
tion, usually indicated by the absence of any great amount of forest 
litter and by the uniformity and the small number of species of her- 


baceous and shrublike plants. On the south slopes and low, dry | 


ridges, where the stand is very open, the yellow pine is quite gener- 


ally infected with its particular mistletoe, working great injury to — | 


the tree. At higher elevations in more moist situations, or even at 
the same level on protected parts of the typical stand, the yellow 
pine becomes mixed with larch, Douglas fir, white fir, and lodge- 
pole pine. The yellow pine gives way to greater percentages of 
larch, Douglas fir, and lodgepole pine on the north and east slopes. 
The two last-named species support large quantities of their respec- 


tive mistletoes wherever the conditions are favorable for the devel- — 


opment of these parasites. The larch predominates in many north- 
slope stands, especially in the more open situations. Other forest 
types in which the larch occurs above 6,500 feet or more are of little 
importance in this connection, since the species of the types at this 


elevation are not as seriously infected by mistletoe as those on north — 


slopes of 5,000 feet altitude and less. 


The influence of drainage, slope, and the general moisture condi- _ 


tions of the soil on the distribution and vigor of the western larch 
is well shown in the region studied and is likewise reflected in the 


prevalence and distribution of its principal parasite. Owing to the ~ | 


general prevailing dryness of the region, the maximum development 
of the larch is attained in moist draws or in fertile valleys not par- 


allel with the direction of the prevailing winds. In such situations ~ 


the tree is usually quite free from mistletoe, and uninfected trees 


often attain a diameter, breast high, of 60 inches or more. A full 


crown composed of the original branches is retained until late in life, 


the tree showing few defects except an occasional root-rot or a dead 
top occasioned by agents other than mistletoe. These situations are 


more favorable to the development of the host than to the mistletoe 


occasionally found upon it and must be considered the best sites for — 


growing larch in these regions. On the drier slopes and benches, 


where the larch is associated more with yellow pine, the influence — 
of the site on the vigor of the mistletoe is at once expressed by its © 


greater abundance and its effects on its host, causing smaller diame- 


ters and thinner crowns on the infected trees. Occasionally trees in 


exactly similar situations for some reason escape the ravages of the 


mistletoe and attain a size of considerable proportions. The full — 


4 
#| 


LARCH MISTLETOE. 5 


- erown and degree of vigor shown by these trees late in life prove 
- conclusively that the ragged, suppressed condition of their neighbors 
is not due wholly to unfavorable climatic or soil conditions, but to 
the effect of the mistletce upon them. 
On some north slopes where the larch is crowded by lodgepole pine 
and white fir it becomes suppressed for a time very early in life, as 
_ indicated by the zone of suppression in the older trees. Those trees 
finally escaping by their more rapid growth from the influence of 
their neighbors usually become infected by mistletoe when the crown 
spreads out to the light and air above. The opportunities for the 
mistletoe to attack suppressed trees with crowns overtopped by other 
species not subject to its ravages are not as great as when the trees 
are standing more in the open. This is due in part to the other 
species protecting the larch from seed falling on it, and in part to 
the fact that permanent tissue incapable of being penetrated by the 
primary sinker is more rapidly developed in the case of suppressed 
individuals. New growth is of short duration and fewer vulnerable 
points of easy infection exist. If the infection of the suppressed 
trees does occur and the infection succeeds for a time, the mistletoe 
plant may itself become suppressed, partly from a poor nutrient rela- 
tionship with its host and partly through lack of light, and eventually 
may die without producing new infections higher up. The signs of 
old infections are frequently noted in the area of the zone of sup- 
pression in trees that have afterwards escaped from the crowding of 
their neighbors. If such trees again become infected later in life, 
they may attain a fair merchantable size before the influence of the 
parasite is made manifest. 


PHYSICAL AND CLIMATIC FEATURES OF THE FOREST REGION. 


The later geological history of the Blue Mountains, in which the 
Whitman National Forest is located, is one of a great basaltic uplift 
surrounding but not submerging the older granitic formations. The 
several high and low laterally arranged ridges are composed in the 
main of granitic rocks, forming a type of soil upon which the yellow 
“pine usually becomes the climax species. Other soil characters in- 
duced by local variations of climate, slope, and type of ground cover 
influence the distribution of the forest trees of this region to a 
marked degree, and indirectly that of the mistletoe. 

Summarizing the chief climatic characteristics of the region, com- 
piled from the reports of the United States Weather Bureau, they 
are (1) scanty rainfall, (2) wide range of temperatures, (3) low 
absolute humidity, (4) rapid evaporation, and (5) an abundance of 
‘sunshine. The influence of such climatic conditions may be con- 
‘sidered in general as unfavorable in a few localities to the best 


6 BULLETIN 317, U. S. DEPARTMENT OF AGRICULTURE. 


development of the larch, but decidedly favorable to the mistletoe 
found upon it. This is at once evident to those familiar with the 
environmental requirements of host and parasite. The region affords 
a most instructive study of the advance and predominance of a forest- 
tree parasite on its host, showing this advance to be in as near an 
exact proportion as the conditions for its optimum development 
become more favorable. 

The problem of the mistletoes in their ecological relationships, re- 
gardless of the fact that they are parasitic, is similar to that of all 
chlorophyllaceous plants; hence, they respond to light, gravity, and 


Fic. 2.—Cross section of a part of a trunk of a larch tree, showing the regeneration of 2 


branches from the same whorl to the fourth generation. (Tape in feet graduated in 
tenths. ) 


chemical influences, and in a far less degree to the influences of tem- 
perature and moisture. How, then, do the ecological requirements 
of the larch mistletoe hold with the climate of the region described, 
over which the parasite is widely distributed? The great variation 
in temperature, occasionally abnormally high, and the late, early, and 
winterkilling frosts of some sections, although seriously injuring the 
host, produce but little effect on the parasite. The uniform dryness 


of the air at all seasons of the year throughout the region does not — 


greatly influence the mistletoe plant, which is essentially xerophytic. 
On the other hand, the large percentage of sunshiny days and the ab- 
sence of clinging fogs are directly favorable to the parasite, as it is 


ee eee 


oa 
fal . 


LARCH MISTLETOE. 7 


positively phototropic. The possible influence of the low absolute 
humidity and rapid evaporation on the entrance of host, reproduc- 
tion, etc., is counteracted by the parasite by means of special struc- 
tures enabling it to withstand long periods of drought. 

Probably no factor of the region so greatly aids the destructive 
effects of the mistletoe on the larch as the high, strong winds so 
prevalent in these mountains. The velocity of the winds is sometimes 
very great. During 1913 hundreds of 
reserved yellow pines on the sales area of 
the Whitman National Forest were up- 
rooted. The wind in this case was mate- 
-vially aided by the insecure rooting of the 
trees on the surface of a hard stratum 
of rocks and gravel, together with a cer- 
tain amount of decay in the brace roots. 
This is a condition often found in cases 
of this kind. 

Strong winds probably do greater injury 
to the larch than to any other conifer. An 
examination of the branching or crown of 
‘a mature or middle-aged healthy larch will 
‘show that in most cases, especially in 
windy regions, the tree has been able to 
‘reach the standard size only through the 
production of several generations of 
branches replacing those broken off by the 
wind and by other causes (fig. 2). The 
loss of branches through crowding or 
natural pruning is not here considered. 
Trees standing under open conditions from 
the beginning will show this interesting Fic. 3.—A larch tree of greatly 
phenomenon of regeneration. Increasing formation at ereat  witvhes. 
age, within a certain limit, on the part of brooms and the accumulation 
the main trunk does not interfere with the °°" Lp yee 3 
“anatomical and physiological connections _ the branches, also the witches’- 
of old branches. Consequently, branches ae. eae is 
forming at any age sufficiently high on the 

trunk to escape the influence of suppression should and would remain 
intact, barring all deteriorating influences, during the natural life of 
the tree. 

_ Trees with wood exhibiting a natural brittleness, which is always 
very pronounced at the bases of branches, suffer greatly from break- 
age by the wind. The western larch is especially subject to this 


attachment with the main trunk is so pronounced that it is not un- 


8 BULLETIN 317, U. S. DEPARTMENT OF AGRICULTURE. 


common to find them lopped off by the wind. This is especially true — 
of tall stems that have come up in close canopy and afterwards 
become more or less isolated. In the case of the larch the ill effects — 
of the wind are greatly augmented by the heavy loads of long, trail-— 
ing lichens (Alectoria fremontii Tuck. and Usnea longissima Ach.) 
supported by the branches (fig. 3). During rainy periods these 
lichens, through the absorption of large quantities of water, increase — 
the weight of the branch by several pounds and, hanging downward ~ 
in a saturated condition, offer a greater resistance to the wind. The 
amount of damage to the 
larch in many locations | 
from this cause alone is 
much greater than is ordi- 
narily supposed. In the 
study in the Whitman 
National Forest it devel- — 
oped that the injury to the © 
larch by mistletoe (aside — 


up the branches and reduc- 
ing the assimilatory sur- 


ure due to the pruning by 
the wind of the many — 
branches which, being 
heavily loaded with 
witches’-brooms, caused an 
increased weight to be ex- | 
A larch, showing the original crown entirely erted at their bases. These 
brooms are often formed 


I'ia. 4. 
removed by brooming. The secondary crown is also 
broomed. The witches’-brooms support large quan- 
tities of “black moss” (Alectoria fremontii Tuck.), far out. on the branch and 


Which grows over and mats the foliar spurs. become densely matted with | 


dead leaves and lichens (fig. 3). This increase in weight often 
amounts to several pounds more than that of a normal branch of the © 
same age and size (Table IT) and is further increased by the absorp- 
tion of water during rainy weather. In the winter the broom fur-— 
nishes a collecting place for snow. It is very evident how the re-— 
sultant of the two forces, viz, the wind in a lateral and the weight 
of the broom-laden branch in a vertical direction, may bring about 
the removal of all the main original branches (fig. 4). It is not 
uncommon to find large heaps of branches heavily loaded with 
brooms under the infected tree. Up to this point the breakage of 
normal wood uninfected by mistletoe roots has alone been considered. 


from the gradual effects of — | 
suppression by brooming 


face) was in a large meas- 


LARCH MISTLETOE. 9 


- The infected wood of the branch, either at its base or other por- 
tions, where not too greatly enlarged by the stimulating effects of 
_ the parasite, requires a much smaller force to break it at the point of 
infection than is the case in normal branches of like age and thick- 
ness. The penetration and embedding of the vertical root system of 
the parasite in the wood of the host add nothing to the strength 
of the infected tissue, but diminish its normal strength when the 
force, as in the case of the wind, is applied at right-angles to the 
grain of the infected branch. Since numerous infections occur at the 
bases of branches, the point of greatest stress, much injury to the tree 
results. The meristematic tissue in the cambium layer at the point 


lc. 5.—Cross section of the trunk of a larch tree, showing a typical basal branch burl. 
Note that the dead wood is attacked by borers which do not encroach upon the living 
sapwood. 

here the branch breaks usually produces secondary branches (see 
fig. 2). These in turn may become infected and are lopped off, so 
that eventually great burls are produced at this point on the trunk 
(fig. 5), seriously reducing the merchantable material. The dead 
wood thus exposed is a place of entrance for insects and fungi. 


nike’ 


Since it requires years for the secondary branches to attain a size 


the parasite, is not able to supply the deficiency in food materials, and 
the tree, merely existing for a time, finally becomes a prey to various 
8521°—Bull, 317—16——2 


10 BULLETIN 317, U. 8. DEPARTMENT OF AGRICULTURE, 


deteriorating agents and eventually dies before reaching its maxi- 
mum development (fig. 6). The radial dimensions of the last annual 
ring of trees in the final stages of mistletoe suppression (fig. 7) _ 


od 


TI'ic. 6.—A larch tree in the last 
stages of mistletoe suppression. 
A few of the witches’-brooms 
contain living branches. The 
tree was making no percepti- 
ble increment and was far be- 
low the normal size for the 
region. It was necessary to 
clear away from the base of 
the tree the heap of fallen 
witches’-brooms before it could 
be cut. 


Fic. 7.—Two larch trees barely living, as evi- 
denced by dissection of the- bole. Note the 
very large witches’-brooms and numerous dead 
branches, 

were often so fine and narrow that they 
could be counted only with the aid of a 
compound microscope. In some of the 
worst cases the tree was able to produce 
but a single layer of tracheids in a year. 
In so far as climate influences the 
prevalence and destructive effects of the 
larch mistletoe, that of the Blue Moun- 
tain region is most favorable. It might — 
be here added that when a particular © 
tree species has succeeded in establish- 
ing itself outside of what may be con- 
sidered its optimum range and at the — 


came time is followed up by a most destructive parasite which 
responds favorably to the habitat, the rapid deterioration of the 
species must necessarily follow, at least in the more unfavorable sites. 


LARCH MISTLETOE. lia 
FUNGOUS ENEMIES OF THE LARCH. 


The larch on the tract examined was not attacked to any extent by 
fungi. The fungi collected were not present in sufficient quantity nor 
were their effects sufficiently evident to be considered the prime factor 
in the universal deterioration of the tree. The dead wood and bark of 
the mistletoe burls were usually infested by the larvee of Jelanophila 
drummondi Wirby (figs. 5 and 8) and occasionally were followed 
by a fungus causing a black stain. Two burls were found infected 


Fie. 8.—Cross section of the trunk of a larch tree, showing characteristic fan-shaped 
burl tissues resulting from an original infection when the tree was 7 years old. The 
tree was 145 years old when cut. Note the presence of borers. (Tape in feet grad- 
uated in twelfths.) 


with Zrametes pint (Brot.) Fr. (figs. 5 and 9), but here, as in a 
number of other cases where fungi had entered at the burl, the hard- 
ness and pitchy condition of the wood counteracted the advance of 
the fungus, and it had not spread much beyond the burl tissue. It 
is safe to state, from long field observations in other regions, that 
mistletoe burls furnish admirable starting points for fungi; but 
since the burl in its early stages is very pitchy (fig. 10) and the dead 
wood becomes pronounced only after the tree is greatly injured by 
the mistletoe itself, the effect of the fungi is to destroy later the 
merchantability of the tree, and the mistletoe may not be the original 
cause of its deterioration. 


12 BULLETIN 317, U. S. DEPARTMENT OF AGRICULTURE. 


THE EFFECTS OF MISTLETOE ON ITS HOST. 


A preliminary survey by the strip method made at the foot of a 
north slope and partly on the level resulted in the accumulation of 
the data given in Table I, showing conclusively that the larch in this 
region is heavily infected with mistletoe. No attempt was made to 
ascertain the age of the trees given here, so as to show the degree of 
suppression. A good idea may be obtained, however, of the nature 
of the infection, distribution, and quantity of mistletoe present on the 


trees. In general, the height of the trees here recorded is somewhat 


less than that of normal or uninfected trees in the same region. 


I"ic. 9.—Cross. section of the trunk of a larch tree, showing a large burl with white 
cellulose pits caused by Trametes pini. Note the small amount of living wood and 
that the dry wood is attacked by fungi and insects. (Tape in feet graduated in 
tenths. ) 


The youngest specimen found infected was less than 5 years old, 
which means, of course, that such early infection will not allow a 
very high state of merchantability to be attained, even if the young 
tree is not killed prematurely. Usually very young growth first be- 
comes infected somewhere on the trunk where the bark is not yet 
protected by cork (fig. 11). The infection of very young seedlings 
causes them to assume various abnormal shapes and positions, espe- 
cially when the mistletoe is confined to one side of the stem. Burl 


LARCH MISTLETOR. 13 


tissues begin to form usually within a comparatively short time, from 
one to two years in young plants. If the infection occurs on the stem 
near the base of a branch, the cortical root system advances into the 
bast tissues of the branch, initiating a burl or witches’-broom at that 
point (fig. 1). The extension of the cortical roots upward along the 
main trunk is sometimes sufliciently rapid to keep within the 4 to 
5 year old portion of the stem, although the larch mistletoe seldom 


Fic. 10.—Cross section of a trunk of a larch tree with a large burl, showing its struc- 
ture and a large pitch pocket. 


spreads very far from the point of original infection. The parasite, 
however, usually travels more rapidly along the young shoots which 
develop in number at the place of first infection. The spread of the 
parasite outwardly along the branch or upwardly along the leader 
may be hastened by the dissemination of seeds from the older infec- 
tions. In this manner the last year’s growth is often infected, and 
even the terminal bud. The branches of the parasite eventually fall 
away, leaving scars easily discernible on the older parts of the 
young trees (fig. 1). 


14 BULLETIN 317, U. 8S. DEPARTMENT OF AGRICULTURE. 


TABLE I.—L£«xtent ma nature of inicttee infection in 36 larch trees m tees 
Whitman National Forest. . 


Number of burls. Number of witches’-brooms. Gen- 
Gen- eral 
gine Height : The eral | mer- 
Tree No. | giam- pe 5 On | At base | At base On Total | Fallen ee = 
eter : of of h on from | trop anal 
trunk. branches.! branches. branches. tree. tree. 4 fea. 
Inches Feet : 
if Dace bate ual eerie 7 51 1 4 5 13 18 13) Boorse eS 
162325 bees 7 68 1 4 6 10 16 1 |...do...| Poor. 
Lib pone area 9 10 0 0 0 0 0 0 | Good..| Good 
ZO Se. ais 10 50 0 0 0 18 18 1 | Fair... Do. 
] W) ire ae aa 11 85 0 2 2 12 14 1 .do...| Do. 
Oat Sere 2 64 0 0 4. 15 19 2 |...do... Do. 
LOE ee eee 12 66 0 0 3 16 19 0 .do... Do. 
aS ie Sa 13 95 0 0 6 12 18 | Dvie 0...) Fair. 
(eee. ees 14 78 0 0 0 0 0 0 | Good..| Good. 
QE Se coe 14 122 0 0 0 0 a AG 0 OSse Do. 
Bike in Smee: 15 98 1 0 4 8 12 _ 2] Fair.. | Fair. 
NS ete meee: 22, 15 84 0 3 4 15 19 3 fe) Do. 
Ui a eeeree Se 15 83 0 0 0 0 0 0 | Good.-| Good. 
1 Sg Say eros 16 88 1 2 4 20 24 3 | Poor.-.]| Poor. 
Leen aes ee 17 85 0 4 ‘a 15 20 17 Gor Do. 
Dies oa ak 2 17 88 2 8 4 20 24 3 .do.. Do. 
Pd. 24 aS 17 90 0 1 2 11 13 1 |...do...| Good. 
Ome? eee 18 99 1 0 3 8 11 1 | Fair...|. Do. 
DA eee hn gee 18 103 0 0 0 0 0 0 | Good.. Do. 
3S eee eee 18 80 1 1 3 5 8 3 | Fair... Do. 
Pl a ee 19 99 0 0 0 0 0 0 | Good.. Do. 
23.2 See 20 103 1 2 4 |. 18 21 4 | Fair...| Fair. 
2A Se ae eee 20 120 0 3 3 20 23 6. \E.cdes.s Do. 
14 Fe ane er ee, Ss 20 109 3 4 3 on 23 41> dox Do. 
Siri ee ee ae 22 107 1 1 3 10 13 0 |...do...| Good. 
Siigiserthey ps 23 100 2 4 8 8 16 9 | Poor..| Fair 
COSA Sa aan 23 110 3 6 5 16 Pail 7 1...do...] Poor. 
SI Se 23 109 4 2 1 10 ‘11 cB 02-5 Do 
303 eat See 24 110 1 2 3 15 18 4) Fair...| Fair 
SOs. eee eee 25 111 2 3 4 10 14 4 | Poor..| Poor 
Pe See 28 126 0 0 0 0 0 0 | Good..| Good. 
ORs A 28 110 1 2 1 10 11 Oa i eh: eel De 208 
1 Ee ee 28 119 3) 1 2 20 22 2 | Poor. .| Poor. 
3 i ein og ER 29 123 3 4 6 10 16 Oe Oe Do. 
pc ae 29 125 0 14 5 20 25 Gul i dos Do. 
Sates Sa Be 30 120 0 3 2 61% 8 0 | Fair...| Fair. 


Owing to the slower growth of the branches in length as compared — 
to the stem, the cortical roots of the mistletoe are enabled to extend 
into the older part of the 2-year-old internodes. After a time the 
branch is suppressed and the terminal bud becomes infected, resulting — 
in a terminal broom. The cortical roots likewise penetrate the foliar 
spurs, causing them to become greatly enlarged, with the result that 
few leaves are produced (fig. 12). It is remarkable how rapidly in 
some instances the bur] tissues become differentiated. A slight swell- 
ing is first noticeable; then the bark begins to lose its fresh appear- 
ance, becomes rough around the edges of the infected tissues, and 
finally separates altogether from the normal bark (fig. 11). The 
vertical roots of the parasite continue to live for many years, elon- — 
gating with the same rapidity with which the annual increment of — 
the host is laid down. The hypertrophied tissues resulting from these — 
early infections on the stem spread out in fanlike shapes when 
viewed in cross section (figs. 8 and 10). Original infections on — 
branches not only cause a local hypertrophy of the immediately 


LARCH MISTLETOE. 15 


infected area (fig. a but large brooms are almost invariably 
produced. ; ‘ 

In mistletoe regions no trees of any age are safe from infection. 
A great many trees surrounded by other species not attacked by the 


ae ae EDGE Eo ea itt ue Fa 1 jh Real iti ee iti cy an Wee eae ae Se HA phHits me 


3 Ye lg 


Fic. 11.—The main stem of a young larch, showing two separate infections, one at the 
whorl of branches and the other on the internode. Both infections are of the same 
age, as indicated by the large primary sinkers, which terminate at the same annual 
ring. Note the rough bark on the swellings, the beginning of typical trunk burls. 
The branches of the mistletoe have fallen, but the sinkers are still living and will 
remain alive for an indefinite period, stimulating the host tissues to a greater devel- 

opment. The central areas oF the burl soon die, leaving an open wound. 

same mistletoe escape early infection and grow to a fair size, with 
normal, healthy crowns. Such uninfected trees are always conspicu- 
ous among their more heavily infected neighbors. These trees are 
eventually attacked, 
but owing to the ad- 
vantage of a some- 
what isolated posi- 
tion, they may not 
become badly in- 
fected, since the 
seeds must be 
brought from a dis- 
tance greater than 
the natural expelling 
force of the seed 
capsule is capable of 
exerting. Undoubt- 


Fig. 12.—A larch twig, showing the abnormal size of the 
foliar spurs when stimulated by the parasite. These spurs 
7 edly this force is are nearly four times the size of the normal spurs on the 


same branch. 


aided by the wind. 
‘The final result is the infection of the terminal twigs, and 


In most cases those of the lower’ branches. The infection 
g radually spreads upward; the branches either become broomed 


16 BULLETIN 3817, U. S. DEPARTMENT OF AGRICULTURE. 


and are broken off, followed in many cases by a secondary crown 
(figs. 8, 4, 6, and 7), too late to supply the deficiency in food 
materials; or the vigor of the present bulk growth and the vitality 
of the tree are reduced by a general infection throughout the entire - 
crown. The latter type of mistletoe injury frequently occurs. The 
~ tree seems to become infected at many different parts of the crown at 
once, and while the branches are not broken by the formation of large — 
brooms, the vitality of the host gradually sinks under the drain on 
its resources of so widespread an infection. When young trees are 
infected there is such an excessive broom development by the time — 
they have reached pole size that the original crown has practically 


Fic. 13.—A common type of original infection on a larch branch, showing the néelanene 
of branch witches’-brooms. 


disappeared. Bushy secondary branches grow out from the stumps — 
of the old ones, and the lopping process may be continued to a third — 
or fourth generation of branches (fig. 2). The width of the second- 
ary crowns becomes less and less, until practically nothing remains 
but the stubs of the former branches, bearing a few straggling green 
twigs (figs. 3, 6, and 7). By this means the assimilatory surface of — 
the tree is gradually reduced. During the period between the fall 
of the primary and the appearance of the secondary branches, the — 
tree is robbed of a great amount of food material necessary to main- — 
tain its vigor at its present stage, and it begins to show signs of — 


LARCH MISTLETOR. 1 


developing a “spike top” (figs. 4,6,and7). All heavily infected trees 
_ by the time they have reached the age of 200 years, if they succeed in 
living to that age, have developed a “spike top” (Table IT). 

Occasionally infected trees attain a considerable size, due to the 
fact that the original infections occurred chiefly at the bases of the 
branches and did not spread. The attendant broom formation oc- 
curring on the branches next to the trunk allows the retention of the 
_ branches for a longer time than if brooms were developed farther out 
on the branch. The merchantability of the tree is greatly reduced, 
_ however, by the formation of a series of basal branch burls, causing 
_ streaks of pitchy wood to extend along the trunk from one burl to 
~ another. | 

The spread of the parasite in the direction of the prevailing winds 
was very interestingly shown in a number of cases. One case in 
particular was noted in which a series of trees of nearly the same age 
_ standing in a row extending in the general direction of the more con- 
_ stant winds indicated that the infection had gradually traveled from 
the first and most seriously infected specimen to those least infected 
at the other end of the row. These trees had apparently originated 
_ under the protection of an old windfall. Since there were no in- 
_ fected trees immediately to the right or left, it is fairly evident that 
_ the wind was a factor in seed distribution and also determined the 
direction of distribution. In order to appreciate thoroughly the 
_ significance of the effects of mistletoe on the larch, a study should be 
_ made of figures 3, 4, 6, and 7, representing different stages of sup- 
pression and various types of infection. 
On the drier slopes, from 80 to 90 per cent of the larch of all ages 
_ has been found infected. On the more favorable sites, the percentage 
of infection was very low and therefore did not interfere seriously 
_ with the best development of the species. (See trees Nos. 40 and 41, 
Table IT.) 
After the preliminary survey, and in order to answer definitely the 
_ question whether or not mistletoe is as great an enemy to the host 
as outward appearance seems to indicate and to obtain, as near as 
_ possible, comparable figures on mistletoe injury, 45 infected and 
_ uninfected trees were cut and such measurements taken as were 
thought necessary for the needs of the problem in hand. These data, 
along with many other observations having a bearing on the subject, 
have been arranged in Table II, whereby it is possible to follow out 
the main factors operative in the deterioration or suppression of the 
trees studied and by means of which fairly conclusive comparisons 
‘may be drawn. 


18 BULLETIN 317, U. 8. DEPARTMENT OF AGRICULTURE. : 


TABLE II.—Comparison of 45 lurch trees in the Whitman National Forest with 
respect to mistletoe infection. 
[ Abbreviations: In columns 14 and 40, increasing degree of infection is shown by the number of cross marks: 


in columns 26, 31, and 32, B= = borers, F=fungi, S=sound, St=stain; in column 36, D=dominant, I= 
intermediate, S= suppressed. ] E 


Branches on Average weight | Averagediame- — 
Branch burls. burls. of— ter of branch. 
ines oeeeSS SSS Highest | Branch |Length 
e Tree point of| witch-| of Su “ 
tenaste NO ree infec- | es’- | spike Branch Sup Normal, 
: Num-| “sc, | Liv-| Origi- | tion. |brooms.| top. | Normal | witch- P ets same 
ber. |}, aight ing. | nally. branches.| es’- >, | partof 
brooms. brooms. whorl. 
1 2 3 fi 5 6 7 8 9 10 11 12 13 
Yrs. Feet. Feet. Feet. | Pounds. |Pounds.| Inches.| Inches. 
SOS AB ae le ora nb ald c.inyaie he ois ee erence 3: eet | eee “2 | w.oie'cnte ses iactoncba te eal ee 
63. | 2iac des eee a|e cee ealee es. Selec cnloceelccec ..s sc peel ante -|ormeu oc ie | e.alcie -c) eens ee rrr 
G3" AZERE onal ocie seine sfecie nl eee 47.0 (hay Pe a 2.0 3.0 0.5 0.8 
(C8 0a ee See eer eee sore See! | ee ee) eee ee 
OW Ge co|co en he ee Tip. {ae2....|. 2... 22. ] cae cece oe ee Dal oY 
oe a es ee ee nee | een ben PE mereene eo ee 
96.) 9 Lill cee. ee ne tell secs] ce + + a cleeles «ve oes oc cece ecclesia rr 
96 | 43 2 2050 hie sas 10 57.0 G perce ee 4.5 1.0 1.5 
100 | 7 3 35.3 10 18 80.0 6c i55.2-. eee 4.5 Lay sere 
105 | 8 1 23.0 3 4 77.0 Bee 5. 25 3.2 1 Bit hen gees des 
106 | 10 il 23.0 2 2 59.0 24 oe ERG 3.2 1.0 15 
107 | Uses wfecseet]..heew the eels eee fetecees . OBR 2. cc agen | ae oc |e eee 
VU | 4 Lf cle ee ewe lectewcfoec coos: Cowen colewc 20 [leo oe crete a fete ere er ee 
DO eC ee a es ee nee Me See ger ee . 
122 | 25. 8 22.4 23 38 95.9 Oo |S asics oa Ca eee 3.8 1:0 besser 
123 | 5 2 38.0 10 14 82.0 LS alF came soe 2.0 3.0), de0 ‘fore 
123 | 44.02). seen] ose ee eels cecee| pos ceeelale ods + cleaner. <lle'- os, fete lee eleie tee er ion 
128 | 135. 3 25.3 15 ‘f 88.5 SBM. pone as 3.2 6.0 1.75 1.50 
1362) Wee ale. ates eee tele meee creer ee 108.0 Uy al (arn) eT ae 8.0 120 jee aoe 
Ce) ee ees eT ee eee me mmme (ee Me oS ) ey 
145 | 3 5 56.4 15 21 92.0 iS lose ote 4.5 8.0 1.0 1.75 
CS ae a es ee) ce ane em | nee POMS oosce5 2 
147 | 19.2 | ce fe nk wee leec cece cs cee s]on cmsccs efgomee cis allen coos © cfc elejeee ote eee 
180 | 23.. 12 41.9 37 72 101.0 tae ee ease 6.0 8.5 1.0 2.10 
183 | 31... 6 49.1 6 20 109.0 OSlcn. nae en 6.0 10.0 1.0 2.0 
R15 5), 12 SRO, 40 Tip, ete). ols... )ee (s) [i ee eee 
216 | 16.5.)...0- 2}. cee seep le cfoe Soc e cule ce ode ccfeacces solace oc cicllce cs cerenle atest 
D222 AT ee 5 37.4 9 21 110.0 15 See 5.0 8.0 95 1.8 
224 | 36... 5 39.2 10 31 Tip. i} 16 |..- 2-222 os) ned erele eee 
295) O65 a le area 3 25 Tip. Meee ae (0)... eee (ay sa ee 
996'|-35-5,) - 42 49.0 5 58 Tin: ee eee Gas oe (¢). “|p2ere a oe 
D2 TN Od orev 9 71.2 23 51 Tip. 10 10 |. 2.0... we Sef ae es cael) Sere eee 
229 | 28.. il 45.5 17 53 Tip. 10 12 (@)) See (@) "Se sence 
233 | 34... 5| 53.0 3 28 Tip. Weekey. 1s .c |. Gy eee (@; Sioos eee 
535 TiS tee G tne aos 7 33 Tip.- Meee soon. coe (e) (2) 1 ee 
245 | 30... 5 54.4 4 19") cee... Heeeeeee ole loooeees (Ff) PE see 
245 | 37. 4} 43.0 3 21 93.0 7 ER a (9) [atch ae 
248 | 32. 7 42.0 7 29 Tip. B | sa. ot eee 25. 0 |-dselerare eee eee 
PAN Dire 12 37.5 19 85 ‘Tip. -eeeeecse 7 (h) © [532255 Sel serene ee ee 
249 | 12. 10 49.3 5 46525 aee...... ee =a 24 (4) . [d.cesccllegec eee een 
252 | 38. 6 67.4 10 39 ARVO. Snes ene ate 3 aoc otv ele eel gheen hehe aaeenee 
253 | 20 3 34. 6 2 18 Tip... faeeses = 42 k) ln... eee Se 
71 i, a a ee ee eee een ne PRM ME Meee okisgsoensss ea 2 
566.) 40...) eel ee at cee leee cel] cece cbc ccc s 2. Wisects well ss cic c le o)-e crete eee er 
623 | AL...) eee eo cafe ee ence ee ele Bile ce = 3 eet 3 lereee eo rel etree bossa 5 
a Branch witches’-brooms fallen to ground. g Crown secondary, infected. 
6 Most original branches broken off. h Branches all fallen. 
¢ One original branch. < Upper crown heavily infected. 
d Original branches broken off. j Branches secondary. 
e Crown secondary. k Branches mostly fallen. 


f Branches fallen; last stage. 


& 
a : LARCH MISTLETOE. 19 
oa . 3 a 
: ‘TABLE II.—Oomparison of 45 larch trces in the Whitman National Forest with 
ie ys respect to mistletoe infection—Continued. 


Burls on trunk. 


Rings in 
: ie sapwood 
g a Occupied by each burl (per cent). (average). 
6 rj 
ES Og 
2 4g <6 | Transverse sec- } A 
8 a ob tion through Cireumference.| «~.)-—:... +-, e 
oe = of living trees. 
a ° center g S 
_- 2 = g : 3 ry . , 3 a 


He OU COO BR 
ee tee See a a 


ee ee ee 


90 BULLETIN 317, U. 8, DEPARTMENT OF AGRICULTURE. io 


TABLE II.—Comparison of 45 larch trees in the Whitman N ational Forest with 
respect to mistletoe infection—Continued. 


Rings comprising | 3 aes : ef 
present period of | © ay oH S M 
suppression. ia ; ; g pe 
3 F 8 | a& lta) 3 
3s z & s | % E oy 
: Tree No. i: 3 g 3 5 s ee 3 Le 
oO . 3 Oo ia n ted) a 
& 5] 2 as q|3 148 18) Soe 
Ga ce cs] iS) 4 >» |G 
3 a rQ a] = Rie fs| > A= =a a : 3 
g, = |ElELEI2/813|8 | 3) eve 
a uM 
4 EF |/2lils/o|lals |2|4) 4 —_— 
ed q 
1 2 29 30 31 32 33 34 35 36 37 38 | 39 40 
Yrs Inches Feet In. | Feet. 
0245. see ee ee 25 15 S s FAO eae NS) 0. 75) [2 2ce Sel eeeee 
OS. DT ees = Ree SARS 0 0 Ss S Oat aera 40 I 6. 65 10 
G3!) ADea ST serie Re tee ee 5 20 s Reese atl. oSsa8 25 Digs 1. 0- 
TA: WOR RR: SASS ee 0 0 S) Ss Sytem 20 it 6 EO: 
OO Nie ie She es oes oe 4 30 B eok oii s 20 SS) 6 1.0 
OF Si Bl pero tense tak ant Ss Be 0 0 Ss S) 97 58 | 340 D {15 12 
96-4) Ole es a ee Sees 0 0 Ss s 72 32 80 I 9 1.0 
OG. PARE: pa etme = Pane .4 30 iS) s 65 30 20 D°s36 1.0 
EO We. eo Ee as 2 6 Ss s 93 48 165 D. jit 13: 
tS 7 ae ee tk ee 3 4 S| sae 95 64 | 265 D {14 1.2 
TOG || Ouse pg hens as .4 30 s S 67 0 40 J "4 1.0 
LOZ. i) Hiller rh aek od eaten 0 0 s S 93 64 | 325 D {16 1.0 
SDD I) SARs fe ts Ras .4 14 Ss NS) 85 48 | 140 Tim 3 
LE Oe eyes, Ree 6 0 0 Ss S {122 80 | 665 D {14 1.5 
Le DD ae ee ere ee 0 0; S S | 64.5 16 75 te 15 
LA RC ae MCE 3 20 S| 84 48 | 170 D /11.5 1.3 
HOS itd Boe 4 ons es 0 0| S | S | 95 50 0} D290. ae oe 
AO SA Sse. co steer tk A 25 10 NS) Ss 93.5 64 | 435 D |17 1.5 
1s) Gl A Ceara oi a Eo a 2 10 NS) S |114 66 | 485 D {19.5 1.5 
10 hae ee 0 0 S S |113.5 82 | 595 D |18 15 
A Sato ee eee 2 30 NS) NS) 95 64 | 240 pg li LS 
CaaS Or ay Cs) ates 0 0 s S {123 94 {1,045 D .-|22 1.6 
PATA Qe. fee ete ee ew 0 0 Ss S {102 80 | 550 Dsige 15 
SO Se fe ee ia 2.5 30 Ss S {113 82} 920 D 2S 1 ss 
EC Is 3 le an aS 2 OR A 15 10 Ss S {119 82 |1,010 D (24 1.5 
208) || Mask a Se ee 2 86 iS} S {100 64] 430 D /|17 1.5 
7A i et (a io Dope eae 1,2 10 Ss S {131 92 | 720 D {18 1.0 
DOP | SUTENEE Uae eee Ae 25 25 Ss Ss /|119 80 | 885 TD 213 1.5 
DOE A BG tes et ee 15 20 Ss S 86 50 160 b Cea i! 1.5 
2D "2OR 2) ees ea 5 40 s S {106 82 | 590 D {19 1.5 
2G ee io Re i ee 45 35 NS) Se 2b 821 790 D {20 5 
Dh | Pour Ree eee 4 38 Ss S 131 98 |1,540 D’ 26 1.8 
ZOO Sh se beet ae Se ae 25 36 NS) S |107.5 82 | 700 D |18 1.0 
ABI (Ray Meno Ea SET ott 15 14 NS) S |104.5 65 | 380 D /|16 15 
Zoo || Se oe kon eee 1.5 13 s 8 |P21 80 | 820 D {20 1.0 
22S Oe Bh 75 48 s S 113.5 82 | 675 D |19 Es 
PAS) Bula tise aoe a eee one 1,15 6 Ss s 97 60 | 380 I |14 1.5 
PAG Bek =< l= Lowe tobe ee 25 20/} S S | 84.5 50] 3051 S {14 1.5 
AON | SO EF ee ees 2.5 80 Ss S {112 90 | 905 D +k 1.4 
AGH SUD SE «it SA We oe en ee 1.9 95 iS) s 88 48 | 470 D {18 1.0 
252) | Soe aa. AS ee ees 25 20 NS) S {120.5 82.| 780 D {21 1.5 
250 || 2Ob 4. oes eeeee 6 50 S S {112 81 | 870 Dit 1.4 
Qi 2a seh: oy 2 ee eee 0 0 Ss §)133.5 98 |1,905 D {81 1.5 
§66.4| AO... 2 SS Secu ete lores see ae eee SelGO. 116.3. oA cee 43 2.0 
68" Ail SSS eee eek a i a oe oe Beeil65 -|.2.Jsclesastaleeee 51 2.0 


a The section passed through burl tissues. 


ree 


LARCH MISTLETOE. < t 


‘The trees were selected from a comparatively small area after the 
_ preliminary survey had shown the nature of the deterioration to be 
universal and similar over large areas of the same type of stand. 
Although the numerical basis for the figures in the table is very 
meager, interesting results are shown, which fully justify the arrange- 
ment. In the absence of suitable volume-table studies of the normal 
_ growth of the same.age class for the region, the arrangement of the 
table is based entirely on the trees felled for study. An increasing 
degree of infection is indicated by the larger number of cross marks 
employed (columns 14.and 40). Selecting trees of the same age, the 
‘study of the table may proceed as follows: Trees Nos. 42 and 27 
are of the same age. The infection of No. 42 is xx; of No. 27,0. By 
consulting column 27 the average width of sapwood for tree No. 42 
is found to be 0.53 inch, and column 28 shows that the sapwood con- 
sists of an average of 16 rings; tree No. 27 has an average width of 
apwood - of 0.9 inch, with an average of 21.3 rings. Tree No. 42 
showed a present per ioll of suppression of 20 rings (column 30), the 
combined width of which is 0.5 inch (column 29); tree No. 27 has 
no present suppression and is marked 0 in the table. The condition 
of the sapwood, sound for both trees (column 31), indicates the ab- 
‘sence of secondary causes of deterioration, as does in like manner the 
column (32) on the condition of the Heatiroodl: Referring to other 
columns, tree No. 42 is shown to have a total height of 53 feet (col- 
umn 33), a full volume of 25 feet, board measure (column 35), a 
breast-high diameter of 5 inches (column 37), and is dominant (col- 
umn 36) ; tree No. 27, on the other hand, has a total height of 60 feet, 
a full volume of 40 feet, board measure, a breast-high diameter of 
6.65 inches, and is sufficiently overtopped and crowned by its neigh- 
bors to be marked intermediate. 

_ The fact that the infected tree stood fairly in the open, with no 
deteriorating agents other than mistletoe associated with it, leaves 
small room for doubt that the tree was suppressed by the parasite 
upon it. Table II shows that tree No. 42 has seven branch brooms 
(column 8), with an average weight of 3 pounds per broom (column 
7 2 on and above the average weight of the normal branch, which 
3 2 pounds (column 10). 

_ The effects of the mistletoe on its host are further shown by the 
Be ances in the diameters of branches supporting brooms and those 
not so encumbered (columns 12 and 13). The analysis of these trees 
showed that both individuals started equally, but the measurements 
and study of all cross sections showed plainly a retarded growth 
during the last few years of life except at the stump, the section 
passing through burl tissues (column 40). The age of the tree can 
not be held responsible for the faliing off in increment. A compari- 
son of the measurements taken at the various cross sections and at 


29 BULLETIN 317, U. S. DEPARTMENT OF AGRICULTURE. 


the stump was found to vary so little that the stump measurements 
were adopted to show the falling off in growth for the last 10 years. 
A study of all the cross sections of tree No. 27 showed a normal 
growth. It also possesses a crown of larger dimensions. The two 
trees stood within 100 feet of each other. Selecting from Table II 
that which is of greatest moment, trees Nos. 43 and 9 may be. com- 
pared as shown in Table III. 


. Tasie III.—Condition of larches Nos. 43 and 9, selected from Table II ee 
comparison. 


Itcm of comparison. Tree No. 43. Tree No. 9. 

ABO. 2. de Boo Rb LRP Ee eee oe. er es ta years... 96 
Breastz=high ‘diameters. 2o05: 2st 2 aaa ee ee ee cee inches. - 6 
Infection? 3... 2. SSeS A Ee. ee 2 eee Exe 
Average width ofsap wood.) s:25-2-- 22. -22te. - cee eo eae inches. . 1.12 
A-verage number of rings In Sapwood ss.) 224 --.< #emee ee. So a eee ae eet aa 

: inches. 4 
Width of present zone of suppression............i...-.-:--.----- rings... 30 
Height 22 sein cnt docs fests eee ck - he Se eee: 2. Ce = ee feet. - 65 
Merchantable lengths.) 2 cake ds ok ects 5 eee. oe eee dois 20 
Full.volume, board measure: 325.5. 2225 2p 2: eee ac a cee dos 20 
Growth for last 10 years. 22 Gis: sakes... : eee inches. . 0.10 IS 
Relation, to:neighboring trees.2-2--.--6 2-2. .< |e ee Dominant. | Intermediate. 


Tree No. 43, as shown by the data in Table IJ, had burls on its © 
trunk and at the bases of branches (columns 3 and 15). A trunk © 
burl occupied 100 per cent of its total circumference (column 20) 
and only 10 per cent of it was living (column 23). The tree had six ~ 
branch brooms (column 6), with an average weight of 4.5 pounds 
(column 11), and normal branches of 3 pounds average weight 
(column 10). 

In this manner tree No. 5 may be compared with tree No. 44; No. 
10 with No. 11; No. 8 with No. 39; No. 5 with No. 25; No. 33 with™ 
No. 35; No. 2 w ih No. 12; No. 30 wath No. 37; No. 33 wil: Nos. 35, 
29, or 36; No. 18 with No. 34, etc. 


EFFECT OF MISTLETOE BURLS ON THE MERCHANTABILITY OF 
LARCH TREES. 


The effect of the formation of burls on the trunk and at the bases of 
branches, aside from injuring the tree from a physiological stand-— 
point by cutting off the transporting tissues, introduces a cull factor 
of no mean proportion in the present timber capital. In bucking the 
tree it is possible in most cases to saw out the burls when they are far 
enough apart not to interfere seriously with the merchantable log 
length. In badly infected specimens the trunk and branch burls 
(figs. 5, 8, 9, and 10) are frequently so close together and so evenly 
distributed along the trunk that little merchantable material can be 
obtained. Sometimes these burls take up the entire merchantable 


LARCH MISTLETOE. 28 


_ part of the tree and are very frequently more than 10 feet in length. 
Streaks of discolored wood, usually pitchy, and long checks may often 
extend from burl to burl, producing a very poor grade of lumber. 
Table IV shows the quantity of culls resulting from the mistletoe 
burls. 


TABLE I1V.—Culled larch lumber resulting from mistletoe burls. 


Trunk burls. Basal branch burls. 


Volume, b.m., 


Volume, b.m., 
of culls due to 


Average diam- of culls due to 


of Tree No. eter. Maxi- 
tree Burl a s,. burls. mat Naas burls. 
No. }---—-— ent. diam- | ber. 
At At For | &ter.2 For 
base. | top. Each. | tree Each. | free, 
Years Inches. | Inches.| Feet Feet Feet. | Inches. Feet. Feet. 
90 | 6 1 6 ee. :. . | Se leo et 2 i! Rll Rais i i De ae 
erg r= - 2 3.5 Bove... ene) | (CB) PaCS Gees ar 165.0 
ilar ee eae ate e 4 oe elas AIR 6 a gl es cea ae ae (b) 20 
1 ws 12 1.5 12 12.3 2 1.4 
> 8 ob ie 11 1.2 9.3 |$ 26.8 rT ee eet el hae 28.2 
{ee 10.1 10 1 5.5 Hyd eine 1.4 
ee 1 15.1 14.8 3 25 25 15.1 1 95 27.5 
6 6 On i gf 7 9 14.5 14.5 9 1 1.4 15.9 
oS ae oe 1 13.5 7 3 20 20 13.5 S.PL'20 40 
So ee 1 8.6 8.3 2 8 8 16 a 5 13 
SE (ae ene: een = I Blo S57 3 10 10 
1 12 11.8 2. 3 15 12 ; 5| 30 
2 Tee) as 10 aes: SAP Oy 
145 | 3¢...---.------ | ST aid 113.8 2 Sa ES Tee eetecen etabeies 67.5 
. 4 10.8 10.6 2 6 TES. Sok 30 
Si a Se eee, Gee lorem eeeeeee peeeremee 12| 180 180 
SSE eee Pie 28 By - 23 3 pot | nite 23.2 6| 175 245 
| 1 i a 1 13.3 13 - 3.5 | 25 d 15.5 12), 170 195 
oD 1 18.5 ie 4 fab oe ree fae — tt a Lae 67.5 
1 18.1 ive 190 as 0 5| 80 
222 | 17......------- DA 97-7 a7 Bl) 2 22 \ 212 { AY Were 80 \ 292 
|| a aS a a fe co ee | 6 4-80 30 
7 a 1 19° 4 13 25°) Meee hte eS 13.5 4| 20 40 
= ae 1 12.8 12.3 4 RE 12.8 12| 140 165 
I ees (eee ce eee Ue leans 9| 190 190 
hs ie ae ae 1 18 17.8 i ae 18 11] 150 260 
ES Re ee (eee ee (ee (ee 5| 60 60 
ss il jeg aS i ie Gen (ene (ND 6 2°80 80 
Sa RS ES ere i Del. ers ( aia 5 70 70 
ES eee Se ie ee eee eee ne 4| 60 60 
ES Se ae i The Cees 16 Te Nee: 12 if iaak 145 
ee eee nt. [ See otecle be nctaclonnes on - 211 190 190 
ES SE ES ae |e eee oe ae (ee 10 | 110 “110 
5 a Se pia i RRR Dir iain De soe eae 6| 95 95 
ra ee 1 18 17.8 16 210 (€) | 19 3| 120 330 


a Average diameter taken between middle line of burl and either extremity. 
b-Tree culled. 

c See figure 8. 

d See figure 10. 

e See figure 9. 


METHOD OF CONTROL. 


_ Since mistletoe is propagated and spreads from tree to tree by 
means of seeds, the method to be employed in eradicating it is similar 
that which is now being adopted in many sales areas for reducing 
the ravages of forest-tree fungi. Results will be obtained in a much 
shorter time, however, than in the case of fungous enemies. Mistle- 
toe occupies only the aerial part of the host. Fungi attack all parts— 


roots, stems, and leaves; hence, cutting an infected tree does not 


tO 


24 BULLETIN 317, U. S. DEPARTMENT OF AGRICULTURE. 


eliminate some of the worst fungous enemies of the forest. Those 
of the roots escape and others attacking the aerial portion of the 
tree afterwards in many cases develop quite as vigorously on the dead 
wood as before. On the other hand, the mistletoe plant dies with 
‘the death of the host. Although thie seeds of the mistletoe are ex- 
pelled from the pericarp with considerable force, they are not carried, 
even though aided by wind, for great distances, as are the spores of © 
fungi. Birds and rodents’ are factors in the distribution of mistletoe — 
seeds, but the actual service rendered the parasite by such agencies is — 
very small. It is very evident, then, that no trees, young or old, in- — 
fected with mistletoe should ever be selected for seed trees, because ~ 
all young growth beneath such trees and in the near vicinity would — 
be in great danger of infection. By a gradual process of elimination — 
cn every timber-sale area, governed by a clause in the contract requir- — 
ing the taking down or girdling by fire of every mistletoe-infected 
tree, much may be accomplished within a comparatively short time. , 


CONCLUSIONS. 


The principal conclusions which may be drawn from the pen . 
study are summarized as follows: a 
The deterioration of the western larch in the more open and | 
exposed stands of the Whitman National Forest is due to mistletoe. — 
Although yellow pine and Douglas fir are the most valuable species, — 
the larch, when free from mistletoe, attains a size on any site, so — 
far as observed, sufficient to merit its being carried along in the © 
rotation with the other species. From the fact that the larch mistle- — 
toe finds its optimum development in the more exposed sites, future 
silvical operations should aim at confining the larch to moist bottoms — 
and protected valleys. 
Since the principal defects of the western larch, excluding pitchy — 
butt and shake, originate from mistletoe, the diameter and age limit 
of this tree may be greatly extended, provided methods for the @ 
eradication of the mistletoe are adopted. ; 
The larch mistletoe attacks trees of all ages, from seedlings to the 
unsuberized parts of mature trees. If not entirely suppressed or — 
killed, trees attacked in early life seldom produce a good grade of — 
merchantable timber. All trees seriously infected show poor health | 
and reduced diameter or height. Trees becoming infected in middle — 
life may have the quality of the timber reduced by the large knots 
formed by the basal branch burls. | 
of the yellow-pine mistletoe in the city park at Coeur d'Alene, Idaho. Mistletoe seeds 7 
have been found in the excrement of birds in mistletoe regions. Birds and rodents fre- 


quently build their nests in mistletoe brooms and are known by actual Bambee: cn to 4 
play a minor role in the distribution of the seeds of the parasite, j 


LARCH MISTLETOE. 25 


_Burls found in early life on the trunk cause suppression by reduc- 
ing the food-transporting tissues, form open wounds for the entrance 
of fungi and insects, and cause streaks of pitch to appear in the 
_ wood, which often extend from one burl to another. Burls formed 
_ at the bases of branches produce similar injuries and may also cause 
a premature pruning of the branch. 

The extra weight of the brooms, together with the accumulated 
-débris, causes the branches to break off readily under the influence of 
the wind and deprives the tree of its normal food supply. 

Mistletoe thrives best on trees of uneven stands. In dense, close, 
_ even-aged stands, as in deep valleys, the parasite usually causes less 
damage. 

The type of infection working the greatest injury in the shortest 
_ time is the formation of brooms on the branches. 

_ Thinning promotes the development of the parasite in the crown; 
hence, all infected trees of any size, age, and condition should be 
‘marked for cutting. 

_ The mistletoe spreads more rapidly in the crowns a younger 
trees, owing to the greater number of twigs in close proximity sus- 
ceptible to infection. 

Two types of infection by the mistletoe occur: (1) By the seed 
falling on the branches, where a broom usually develops if infection 
occurs, and (2) the gradual advance of the cortical root system of the 
mistletoe along the branch to younger tissues. The seeds of mistletoe 
have been known to fall on the healing tissue of wounds on old parts 
of trees, causing infection. 

_ Suppression by mistletoe causes a more rapid and an earlier forma- 
tion of heartwood in the younger age classes, thus inviting insects and 
fungi at earlier periods of growth. 

_ Mistletoe may be controlled by inserting in all timber-sale con- 
tracts a clause requiring the cutting on the sales area of all larches 
infected with mistletoe, whether merchantable or unmerchantable. 


: 


ee ee 


a a ee ee 


| PUBLICATIONS OF U. S. DEPARTMENT OF AGRICULTURE RELAT- 
ING TO FOREST TREE DISEASES. 


AVAILABLE FOR FREE DISTRIBUTION. 


_ Forest Trees, Diseases common in California and Nevada. (Forestry Mis- 


Be, Suk. Quercus garryana. (Forestry Silvical Leaflet 52.) 
FOR SALE BY THE SUPERINTENDENT OF DOCUMENTS. 


Diseases of Deciduous Forest Trees. (Bureau of Plant Industry Bulletin 
149.) Price 15 cents. , / 

_ Mistletoe Pest in Southwest. (Bureau of Plant Industry Bulletin 166.) | 
Price 10 cents. 

 Plant-disease Survey in Vicinity of San Antonio, Texas. (Bureau of Plant 
Industry Bulletin 226.) Price 20 cents. 

Diseases of Ornamental Trees. (Separate 463 from Yearbook 1907.) Price 
) cents. 

ae 


ADDITIONAL COPIES 


OF THIS PUBLICATION MAY BE PROCURED FROM 
“THE SUPERINTENDENT OF DOCUMENTS 
GOVERNMENT PRINTING OFFICE 
WASHINGTON, D. C. 

AT 


5 CENTS PER COPY 
A 


WASHINGTON : GOVERNMENT PRINTING OFFICE : i916 


oo ‘ 
ee A q Ls 
- 
a « ri 
7 . i 
b ¥ p ‘* 
‘ 
ae ; oa “ 
+ EE 
ie ? 
LA ( é 
+ | peer’: 
7 
: 
j<<ye 
. 
9 ¢ 
- ~! —_ ete wns te 
va 
73 
ae “ 
, = 
' 
2 
if : 4 - 
Sas 
.* 
; 
Mise 
¥ 
is } 7 >, . 
\- ‘f y 
z ca) 2 
S| 3 
i.e 
«8 = 
y ba : ., , i 
Pe B ‘r) v a 
A 
\ x 
z . s . . 
af 3 
o: ‘ r : 


5 pipe, ae pe: “s 


im 


i 
i 


babe Ree ot i 
ee." : 
. » 
nee 
e 


UNITED STATES DEPARTMENT OF AGRICULTURE 


BULLETIN No. 360 ¥ 


UM 
<S7 
\ES 
PENNS 
se Na 
oD be 
{ g 


Contribution from the Bureau of Plant Industry 
WM. A. TAYLOR, Chief 


PROFESSIONAL PAPER June 17, 1916 


MISTLETOE INJURY TO CONIFERS IN THE 
NORTHWEST.’ | 


By James R. WEtr, 


Forest Pathologist, Office of Investigations in Forest Pathology. 


CONTENTS. 
Page. Page. 
Eo 1 | Relation of mistletoe injury to insects....... 28 
General nature of the mistletoe injury.-.....- 2 | Influence of mistletoe injury on the seed pro- 
Result of infection on the branches........-. 13 duction.of tae host... .cu--2: 4. ::.2.-.-225.5 30 
Result of infection on the trunk. ...........- 20 | Host affinities in relation to silviculture... ... 31 
Relation of mistletoe injury to fungous at- Suggestions for control). -).2. . 2. 2....2.se885- 33 
ga 2 eo ESS Oh |) pe UIT is cl arate = Crate ben ts W eee tw cle See 37 
General suppression and fungous attack..... or |) Litemaure Cited... g.2.66e Sb bet te ete Meee 39 
INTRODUCTION. 


It is not generally known that the injury by the mistletoes to 
coniferous trees in the northwestern United States is such as to 
assume in many regions the nature of a serious forest problem. 
The aim of this bulletin is to point out some of the direct and 
indirect results of this injury. The species of trees most subject to 
injury are Larix occidentalis (western larch), Pinus ponderosa 
{western yellow pine), Pinus contorta (lodgepole pine), and 
seudotsuga taxifolia (Douglas fir). Each of these trees is attacked 
y a particular species of mistletoe of the genus Razoumofskya 
Arceuthobium). With a few exceptions, these species very rarely 
cur in nature on any other than their common hosts. In the 
rder of the above-named hosts they are Razoumofskya laricis Piper 
Pl. I, fig. 1), R. campylopoda (Engelm.) Piper (Pl. II, fig. 2), 
. americana (Nutt.) Kuntze (PI. I, fig. 2), and R. douglasit (En- 
elm.) Kuntze (PI. II, fig. 1). 


%. 1Thanks are due Mr. E. E. Hubert for assistance in the preparation of the graphs and 
: . number of the other illustrations used in this bulletin. 


» 24182°— Bull, 360—16——-1 1 


2 BULLETIN 360, U. S. DEPARTMENT OF AGRICULTURE. 


GENERAL NATURE OF THE MISTLETOE INJURY. 


The general nature of the injury to forest growth by these para- 
sites principally consists sooner or later in a localization and gradual 
reduction of the assimilatory leaf surface of the host. As will be 
shown, this is caused by various burl and broom formations on the 
trunks and branches. The reduction of the leaf surface causes a 
falling off of the annual increment. During the progress of a study 
on the larch mistletoe in the Whitman National Forest, Oreg., in the 
summer of 1913, many data on the retardation of growth of its host 
by this parasite were assembled. More recently, in the lodgepole and 
yellow pine belt of eastern Washington and northern Idaho, the study 
was continued on these species, and at frequent intervals on the larch 
and Douglas fir in the Missoula region of Montana. The method of 
investigation was as follows: Borings from heavily infected (burled 
and broomed) and uninfected trees were taken with ‘a Mattison 
increment borer at 44 feet from the ground, at which point the 
trees were calipered. With practice the eccentricity of growth due to 
slope, unequal crown development, injuries, etc., may be very skill- 
fully judged, so that it is possible to strike the pith of trees within 


the range of the borer with a fair degree of accuracy. In order to 
determine as nearly as possible the average radius, in the more doubt- 


ful cases three borings were taken. On steep slopes the eccentricity of 
trees may be more accurately judged than on flat land, through the 
‘knowledge that more rapid growth takes place on the downhill side 
of the tree. Height was computed with the Klaussner height meas- 
urer. Trees of the same species were selected as near as possible from 
the same type of stand and of the same general age class and the same 
soil conditions. Only dominant trees free from serious wounds and 
other possible causes of deterioration were recorded. Finding that 


the effects of the mistletoe on the increment of the host could be read © 
from the last 40 years’ growth of the age classes and conditions of | 


infection selected, Table I was prepared. 


TABLE I.—The retardation of growth of forest trees caused by mistletoe, for 40 
years, 1874 to 1913, inclusive. 


Average. 
Basis 
tea num- 
Host and condition. ie of Diameter| Total 
trees). |Ageclass.| Height. | breast | annual 
high. growth. 
Pinus contorta: Years. Feet. Inches. Inches. 
Tnfeeteadise | 52 ous ays. akh oe es Oh or 50 65 35i:2 6.3} - 0.93 
Winiinteetéd.s fist 6 cb. See Eee ee 50 60 48.5 7.8 2.93 © 
Pinus ponderosa: : 
niectoad sso. 2.0 2a. soe es eee 50 100 49.5 18.2 154g 
Umintected soc 5526 Shs eee. eee 50 100 (EY 22,2 5.33 
Larix occidentalis: 
Tntected iv, ccrctec uals secede Sub: oh. Bee 80 144 63.0 11.5 1.28 
Umimteeted: 223 sersiek conc oe eee oc ees ee ee 80 144 115.0 19.5 2.154 


Pseudotsuga taxifolia: 


Infected =. .2i6. tcc oboe 40 97 62.0 17,3 2.175 | 


Usiintected 5-.28: 3.0. i. Shee Se ee eee 40 97 73.0 229 3. 28 


Se eee 


MISTLETOE INJURY TO CONIFERS. 3 


The results in Table I, although based on a relatively small number 
- of trees, prove quite conclusively the effects of mistletoe on the 
growth of its host. They are graphically shown by the accompany- 
_ ing series of illustrations (figs. 1 to 4). 
_ A glance at these graphs shows that although there is considerable 
fluctuation in growth, the line of the uninfected rarely falls below 
that of the infected trees. 

These results are not at all surprising when the nature of mistletoe 
injury is thoroughly appreciated. In a heavily infected region, 
where all species and ages are more or less involved, dead, dying, or 


POT 
PETE 
POE 
POULUNEE EEE LET EEE ANT 
ETA 
JNA 
POE TM 
SALA 
PUNTA 
ARRAN TP 
PL NE 


a 


Fic. 1.—Graphs showing the average annual growth (in inches) for 40 years (1874 
to 1913, inclusive) of 50 trees of lodgepole pine heavily infected with mistletoe, 
compared with 50 uninfected trees of the same species for the same period. A, 
Heavily infected trees: Average-age class, 65 years; average height, 35.2 feet; 
average diameter, breast high, 6.3 inches. B, Uninfected trees: Average-age class, 
60 years ; average height, 48.5 feet; average diameter, breast high, 7.8 inches. 


weakened mistletoe trees, hastened in their decline by the inroads of 
fungi and insects, are a common sight. If these trees are carefully 
examined with respect to the average possible growth for the region, 
it will be found, as Table I shows, that most. of them have died or 
have become irrevocably weakened or suppressed at a time when rapid 
or a normal growth should be taking place. This has been found 
_ to be true in all regions visited in the Northwest where excessive 
mistletoe infection is common. Infected trees of immature years, 
i pole size and younger, may linger along indefinitely if secondary 
_ agents do not appear and may reach an advanced age, but may not 
. attain a merchantable size. Heavily infected and, as a result of this 


2 
q 


a 


infection, badly stunted yellow pine, larch, Douglas fir, and lodge- 
pole pine growing in the open and on otherwise good sites often 
measure less than 6 inches at the stump, but show ages ranging from 
Young seedlings, if not killed outright 
within a comparatively short time after infection, usually show a 


100 to 200 years or more. 


SE 
ope 


6 


AVERAGE ANNUAL GROWTH /NCHES 


BULLETIN 360, U. S. DEPARTMENT OF AGRICULTURE. 


CEE 
MELLEL ET 
CAE A 
GAVANGTAUGUAPARUGAEWEVAWGV(A0K,NOKELE 
PAE EEE Pag ee HEA 


PEIN tat 
AEE ENT PS 


1874 S885 S89. 1905 7H10 (H/F 


Fic. 2.—Graphs showing the average annual growth (in inches) for 40 years (1874 


marked falling off of the foliar surface of the parts uninfected and 
finally succumb to the attack (fig. 5). 


to 1913, inclusive) of 50 trees of yellow pine heavily infected with mistletoe, com- 
pared with 50 uninfected trees of the same species for the same period. A, heavily 
infected trees: Average-age class, 100 years; average height, 49.5 feet; average 
diameter, breast high, 18.2 inches. B, Uninfected trees: Average-age class, 100 
years; average height, 77.2 feet; average diameter, breast high, 22 inches. 


fected seedlings develop into ball-like brooms. 


Table II shows the youngest age class of five hosts at which mistle- 
toe infection has been found to occur and the locality where the 


observations were made. 


Very frequently young in- 


# 


= 
| 
: 


MISTLETOE INJURY TO CONIFERS. 5 


TABLE II.—The youngest age class of mistletoe infection on five different hosts. 


nS em his) Be 
rouse 


age 
oreo Locality where observations 
| Host. infection were made. 
is known 
to occur. 
; oe 
Years. 
eee CueNsuEe EI ae oS. c Hoenn ea + ocean eee 4 | Clark Fork Valley, Mont.! 
LL 2 ee Be See 5 eres 7 | Blue Mountains, Oreg. 
Larix odeldentalis ee Se ee eR ee See Pee eee 2 5 | Priest River Valley, Idaho. 
es ees ee oo ee 4 | Blue Mountains, Oreg. 
Won as lo NR aie Ree eee ae eee 3 | Missoula, Mont. 
a ele a eee 7 | Sullivan Lake, | Wash. 
(THES LSTA. 2 ee Se Re nm era ee 5 | Spokane River, Wash. 
Te tp wo oe o tee ee ee en Sern ae 3 | Blue Mountains Oreg. 
SE AT eee Soar 6 | Coeur d’Alene, Idaho. 
Pinus Le ah 5. te) Ae See aed Sie ae aR es ee 2? Se 5 | Spokane River, Wash. 
ts eR. da cidet  aewles b's woe eetedes st - 3 | Blue Mountains Oreg. 
ae ot i eS ees oie 4 | Coeur d’Alene, Idaho. 
Sts | ES Be eee ee eee or ee 8 | Clearwater River, Idaho. 


1 Valleys of the so-called Bitterroot and Missoula Rivers, 


There is no reason why a seedling should not become infected 
during its first year if seeds should happen to be favorably located 
upon it. Seeds falling at the base of terminal buds of yellow-pine 
branches have been known to effect an entrance in the succeeding 


ALL AL 
DREN YN 
indie 


5 
‘ 
d 
a 
\ 
: 
c 
‘ 
» 


i 
(i 
a IN| | pinis 
PE 


I 
we aided 


Ree ee 
Bibs ga 
Beane 
eagage 
yoy eas 
garage 
VAL 
Bia 


[| 


es a 
L&R): Sa a ae oe 


AVERAGE AIVVUAL GROWT// UVCHIES 


eee EEPEEELELEETETLE EEE EEE EEE 
(874 1880 S885 7890 S895 1900 1905 “HO ¢H3 
FEARS 


_ Fic. 3.—Graphs showing the average annual growth (in inches) for 40 years (1874 to 
1913, inclusive) of 80 trees of western larch heavily infected with mistletoe, com- 
pared with 80 uninfected trees of the same species for the same period. A, Heavily 
infected trees: Average-age class, 144 years; average height, 63 feet; average diam- 
eter, breast high, 11.5 inches. B, Uninfected trees: Average-age class, 144 years; 
average height, 115 feet; average diameter, breast high, 19.5 inches. 


season’s growth within the year. All infections of firs and spruces 
have been found on trees ranging from 50 to 150 years. They 
occurred principally on the branches, resulting in large brooms, so 
that nothing could be determined as to the probable age of the hosts 
when infection took place. 


6 BULLETIN 360, U. S. DEPARTMENT OF AGRICULTURE. 


No evidence is at hand to show that the primary sinker of these 
parasites can penetrate other than the more tender epidermis of 
young parts of the host. Germinating mistletoe seeds located on 
the smooth bark of the Douglas fir or on the irregularities of older 
stems of yellow pine or larch have never been observed, even after 
a protracted contact of the disk of the hypocotyl with the surface 
of the branch, to penetrate the bark. Removing the exhausted 
hypocotyl and carefully examining the point where the disk was 
attached, a barely perceptible pit or indentation is sometimes visible, 


“nn 


ALLA TT 

PRU CRA CPCI 

AEC ATEME AREER 
WAM 

HOGEEAR AG AGG 

é WV 


20 


AN 
HEED 
LTE AE eT 
TET eT 
MEME EEE GEE 
hs he gle a ak 


1874 45W3 


RS IS, OS OR. SPN 
serine etna 


AVERAGE ANNUAL GROWTH. /NCHES 


. Fic. 4.—Graphs showing the average aha erik (in inches) for 40 years (1874 
to 19138, inclusive) of 40 trees of Douglas fir heavily infected with mistletoe, com- 
pared with 40 uninfected trees of the same species for the same period. A, Heavily 
infected trees: Average-age class, 97 years; average height, 62 feet; average di- 
ameter, breast high, 17.3 inches. B, Uninfected trees: Average-age class, 97 years; 
average height, 73 feet; average diameter, breast high, 22.2 inches. 


possibly indicating the presence of a solvent, which, however, is 
ineffective upon more mature bark. There is as yet no proof to sup- 
port the theory of the presence of a digestive substance which 
enables the sinker to penetrate the bark more readily. If this were 
true, infection could possibly occur on older tissues, provided they 
were not too thick and the food supply in the seed did not become 
exhausted. As it is, mechanical force, supported by the nonmov- 
able position of the seed, and irregularities of the stems, such as 
leaf scales, exits of leaf traces, and leaf sheaths, particularly at 


aAVIN, 
a 


BAR me ed FLA 2 eM i eo om A 


ee ee es nh 


: 


OO ee ee ee 


Eee 


, a 


Na 


MISTLETOE INJURY TO CONIFERS. 7 


the nodes and the basal scales of the terminal buds, are the chief 
factors in the penetration of the primary root. 

The occurrence of mistletoe plants on the thick-barked branches of 
old trees or on the main trunk are the result of earlier infection, 
when the bark was thinner. What appears to be a recent infection 
on the older parts of trees is often merely a retarded or suppressed 
condition of an earlier in- 
fection which has ex- 
pended most of its energy 
in the production of a sub- 
cortical stroma and later 
breaks through the bark. 
Periods of suppression and 
dominance are frequently 
noticeable in all mistle- 
toes, a condition noted to 
be in several instances di- 
rectly referable to the 
state of vigor of the host. 
An excessive flow of resin 
sometimes appears in the 
second and third year of 
the life of a new infection 
on larch and yellow pine, 
which, if not fatal to the 
young plants, may seri- 
ously retard their growth 
for years. Until infection 
by actual inoculation, 
using natural methods, is 
attained, all statements of 
the ability of the parasite 


Fic. 5.—Four-year-old yellow-pine seedlings killed by 
: mistletoe. Note the hypertrophy of the stem at 
to effect an entrance in the point of infection and the shortening of the 

st needles. The two seedlings on the right were 
old barked branches , Or killed principally by having the wood and cambium 
trunks can not be accepted in the swelling infiltrated with pitch. The para- 


site killed the seedling on the left by invading the 


and must be considered ein gcah Gee 


faulty observation. The 

writer has never succeeded in causing the infection of branches at any 
point older than four years. The ease of infection is found to be 
more or less in proportion to the decrease in age of the branches 
tested. This was proved in the case of yellow pine by inserting 
seeds at regular intervals in the axils of the leaf sheaths of young 
branches, from the terminal bud to the tenth internode. The results 
of this experiment are shown in Table III. 


8 BULLETIN 360, U. S. DEPARTMENT OF AGRICULTURE. 


TaBLeE III.—IJnoculation of Razoumofskya campylopoda on Pinus pomdanosa, 
made in November, 1911. 


[x= Inoculation effective; 0=inoculation not effective. ] 


Seeds | Results in November, 1914, on branch— 


Age of part of branch tested. 
ternode. | No.1. | No. 2. | No. 3. | No. 4. | No. 5. 


Season’s growahter Aas. |e Rees oe oe ees 10 Bic x x 0 0 
EUYOa 0... . 2 Meter n a5 gee min = os Dales we eee Boe 10 0 0 x x 0 
DV GATS |< seca tersemree Sento rae erat a oa eee a 2 ae 10 0 0 0] 0 xX 
@ FORTS Gis eae iain ode niece ke eo 5 ei ea 10 0 0 0 0 0 
4 YOSIS as Sareea eee haa 3 [5.2 cesta as eee oe 10 0 0 0 0 0 
D VOCALS: oars eat cies Awa. 2.8 © Se aeteme, oe esc ' tae ae 10 0 0 0 0 0 
@ VOars. 2. see aeihe nine s.6)« =, tle SE cle/e-~ afte a ae 10 0 0 0 fo 0 
0 YORIS .. eee geal ean inn = - SO a nen a > <2 10 0 0 0 0 0 
8 YOaNns\y. 2. {see ck eee - - 0 erent or, <2 ae ae 10 0 0 0 0]: 0 
9 VeCGIS. Wiis Jie 5 Se clo oS ete a oso! 2 10 0 0 0 0 oO 
10 years), 32226. en We we eee aces <. See 10 0 0 0 0} 0 


A study of Table III shows that the branches were infected in 
three out of the five test cases on the youngest and last internode on 
which the seeds were placed. Infection occurred on two of the five 
tested branches on that part 1 year old at the time of sowing, one 
infection only being on the 2-year-old portion. Infection did not 
take place on the older parts of the branches. A tree never be- 
comes too old for infection to occur on its youngest branches. Sup- 
pressed trees may escape, owing to the fact that slowness of growth 
and more rapid formation of thick bark lessens the chance of infec- 
tion; also shortness of twig growth gives less opportunity. The 
demand for a fair amount of light is also a factor in such a case, 
not, however, for the stages of germination and penetration of the 
primary root, but for the subsequent development of the aerial parts. 
Mature trees becoming infected on tender branches may not suffer 
any appreciable injury, but in time the decline of the tree is surely 
hastened, since the gradually increasing hypertrophy of the branches, 
the breakages, and the thinning out of the foliage of the tree as a 
whole cause it to be greatly weakened. Almost always the result of 
a heavy infection on the trunk and branches of some conifers is the 
death of the upper portion of the crown,’ causing staghead (fig. 6), 


1The dying back of the crown of trees, commonly known as spiketop, or staghead, is 
attributed to various causes; as many, in fact, as the varied conditions under which trees 
grow. One of the most common theories is that on opening up a stand the admission of 
light to the trunk and lower crown defiects the transpiration current to the older branch 
orders or, aS with some species, promotes the formation of a secondary crown on the 
main trunk. This stimulated foliar activity below reduces the water supply at the top 
of the crown; consequently the topmost branches die back. This is exactly what happens 
in the case of mistletoes. The extra crown development below, by brooming, starves out 
the crown above, resulting in its death. Miinch (Silva, December, 1911, pp. 415-416) 
claims to have found a parasitic Ascomycete which causes staghead in the oak of Europe 
by attacking the bark and outer wood of the main shoots. The writer has found a 
wood-destroying fungus which attacks the upper crown branches of the chestnut in 
southern Indiana and causes their death. The ‘“ pencil rot,’ which seems to be fre- 
quently the cause of staghead in the western red cedar, is another example of fungi at- 
tacking the crown of trees. Lightning is a common cause of. staghead; also injury by 
insects. 


a ee 


> ip 


Bul. 360, U. S. Dept. of Agriculture. PLATE I. 


Fic. 1.—BRANCH OF LARIX OCCIDENTALIS INFECTED WITH RAZOUMOFSKYA LARICIS. 


The staminate and pistillate plants are in close juxtaposition, the former at the end of the twig. 


Fic. 2.—RAZOUMOFSKYA AMERICANA ON PINUS CONTORTA. 


Staminate and pistillate plants; long trailing form, 


Bul. 360, U. S. Dept. of Agriculture. ~ PraTe Il. 


FiG. 1.—RAZOUMOFSKYA DOUGLASII ON PSEUDOTSUGA TAXIFOLIA. 


Staminate plants, slightly less than natural size. 


Fia. 2.—RAZOUMOFSKYA CAMPYLOPODA ON PINUS PONDEROSA. 


The staminate and pistillate plants are growing close together on the same branch, a very 
common condition for all species, but not generally known. 


Bul. 360, U. S. Dept. of Agriculture. PLATE III. 


Fia. 1.—AN OPEN STAND OF YELLOW PINE HEAVILY INFECTED WITH RAZOUMOFSKYA 
CAMPYLOPODA. 
Note that some of the treesare dead and that others have very thin foliage. The structure of 


the dead brooms is plainly shown. Some of the trees bear burls on the main trunk. The 
young growth is seriously infected with mistletoe. 


4 


Spal 
LLG 


Fic. 2.—A HEAVY GENERAL INFECTION OF A 15-YEAR-OLD YELLOW PINE BY RAZOU- 
MOFSKYA CAMPYLOPODA, RESULTING IN A DISTORTED AND OPEN CONDITION OF THE 
CROWN WITHOUT PRONOUNCED BROOMING. 


The natural excurrent growth of the main trunk is entirely changed. 


Bul. 360, U. S. Dept. of Agriculture. PLATE IV. 


Fia. 1.—NEEDLES OF DOUGLAS FIR FROM A NORMAL BRANCH (AT THE RIGHT) AND 
OF A MISTLETOE BROOM ON THE SAME TREE, SHOWING THE DIFFERENCE IN SIZE. 


Fic. 2.—YELLOW PINE AT THE HEAD OF A CANYON, SHOWING MISTLETOE INFECTION. 


Note that the heaviest infection occurs on the immediate edge of the canyon and that the 
intensity of the infection decreases as the distance from the brow of the canyon increases; 
also that the upper crowns of the infected trees are becoming very thin. 


‘of all age classes has 
been growing worse, 


the drainage basin of 


MISTLETOE INJURY TO CONIFERS. 8) 


or in some cases the entire tree may succumb (fig. 7 and Pl. III, fig. 
1.) In many parts of the Whitman National Forest, wherever the 
heaviest infection of yellow pine occurs the percentage of dead or 
spiketopped trees reaches a comparatively high figure. 

In a report to Supervisor Ireland, Ranger Smith, in referring to 
the seriousness of the infection of yellow pine in the vicinity of 
Susanville, Whitman National Forest, states that since 1907, the 
year in which the mistletoe damage in the region first received at- 
tention, the infection 


probably 40 per cent 
of the stand now be- 
ing infected. Of the 
more mature stand, 
approximately twice 
as many trees near 
the station as were 
noted in 1907 have 
since died. Ranger 
Smith further states 
that for a most pro- 
nounced general in- 
fection of all species 


| 
{ 
i 
; 
£ 


the South Burnt 
River particularly 
ulustrates the devas- 
tating effects of mis- 
tletoes. “Almost 
every yellow pine 
from seedlings up 


and Douglas fir above Fic. 6.—Douglas fir, showing the death of the upper por- 


sapling size 1s heavily tion of the crown caused by Razoumofskya douglasii. 
F The tree to the right with the series of immense brooms 
infected and most of also has a dead top. A large broom had split off from 
the mature timber the trunk of the tree on the left. All the young growth 


2 in the vicinity of these trees is seriously infected. 
shows great retarda- 


tion of growth and is now adding little or no increment. This 
infection covers a large part of the best yellow-pine sites in the 
yellow-pine belt of this watershed.” This region was not visited by ° 
the writer, but to judge from studies in other parts of the same 
forest Ranger Smith’s observations are undoubtedly correct. 

In order to determine the relative amounts of different species 


eut as snags on the W. H. Eccles Lumber Co. sale (Whitman Na- 


9 


24182°—Bull. 360—16 Ps 


10 BULLETIN 360, U. S. DEPARTMENT OF AGRICULTURE. 


tional Forest), the following figures were assembled by Mr. T. J. 
Starker, covering a period of 28 days of cutting: 


Western ‘IaFenio7) 92 2. BA oy eee A eee Oe 556 
Western yellow pine... s~-.b 2p eee ee 1, 232 
Douglas fires- .. + cs ae Se ie 422 

Netal 2620 25. oh ee tO 2, 199 


It must not be assumed that the death of these trees resulted 
from mistletoe. It is doubtful whether the death of even a small 
percentage of them, with 
the exception of the larch, 
can be so referred. A more 
conservative statement 
would be that mistletoe had 
a large share in their death 
by causing spiketop, the 
brooming of branches, and 
the formation of burls on 
the trunk. These are com- 
mon forms of mistletoe in- 
jury for all three species in 
this region and lead up to 
serious insect infestation, 
of which more is said later. 
That mistletoes are capable 
of actually causing the 


rs 


BTN 


— 


SRN Aang” a? / Be 
= ; ‘ = J cA : \ 
wre ~~ eo “oe “es be: 
The is : ? 8 
‘ 


“P 


we 
Se 


ae 


young growth from three 
to eight years old. In a 
heavily infected but very 
open stand of yellow pine 
on the bench lands of the 
lic. 7.—Douglas fir killed by mistletoe. Note the Spokane River, Wash. (Pl. 


total absence of normal branches. The structure TY, fig. 1 an attempt was 
of the brooms is here plainly shown. Note the 


straight trunk of the larch in the background. It made to ascertain the 
is uninfected by mistletoe and still retains its amount of injury resulting 


original branches. 

to the seedlings of an aver- 
age sample acre, which included in its area nine semimature and 
heavily infected trees in all stages of suppression. The acre was 
divided into plats and all young growth counted and examined as 
to infection and the condition of the infection. \The number of 
seedlings and small growth below 8 feet in height totaled 480, which 
is an excellent reproduction for this region. Just a little more than 
half of this number, or 245, were found to be infected, representing 
every possible type of infection on stem and branch. It is not to be 


expected that these seedlings would ever grow up to form merchant- ~ 


death of their hosts is first © 
shown by their effects on | 


+ PAs Peete won 


MISTLETCE INJURY TO CONIFERS. ‘mk 


able trees. Considering the severity of the infection, they could 
not be expected to attain near the size of their parents shown in 
Plate III, figure 1, and from which they received the mistletoe. 
Of the 245 infected seedlings, 49 were dead. An examination 
of the root system of each 
seedling showed it to be well 
developed. In the absence 
of any other deteriorating 
influence except an _ occa- 
sional needle infested by 
Chionaspis pinifolia Fitch, 
the death of these seedlings 
must be ascribed to the lux- 
uriant growth of mistletoe 
which they had supported 
(fig. 5). In most cases the 
tufts of mistletoe had fallen 
away. The bark of the 
large fusiform swellings 
was usually ruptured and 
both the wood and bast tis- 
sues were so heavily infil- 
trated with pitch that the 
passage of food materials 
between the crown and the 
roots was wholly impossible, 
resulting in death. In this 


respect there is a parallel 
Fic. 8.—A group of Douglas firs with their entire 


between this type of mistle- lower crowns developed into brooms by Razou- 
toe injury to seedlings and ~~ mofskya douglasii. Note the sparse foliage of 


: the upper crowns and the young brooms in the 
o 
that resulting from the tree ‘on the right, showing how the parasite 


perennial mycelium of some travels upward. The branches between the 
eaulicolus Peridermiums. brooms have died from lack of nourishment, 
A further study of the large trees shown in Plate III, figure 1, is 
illuminating. Two of them, the right and the left in the figure, are 
_ dead. Scarcely a single normal branch is to be seen, but instead are 
- numerous large gnarled and distorted brooms. These trees measured 
on an average 9.3 inches in diameter at 44 feet from the ground, and 
increment borings showed the age of each to be 190 years. This is 
far below the diameter of normal trees of the same age for the 
region. A careful search for secondary causes of injury resulted 
negatively. The trees were absolutely sound. Lightning injury, 
Which sometimes causes spiketop in yellow pine and other conifers 
- and which sometimes is erroneously attributed to mistletoe, was not 
_ present. With the evidence in hand, it is safe to state that the trees 


24 Pcs 


% 


12 BULLETIN 360, U. S. DEPARTMENT OF AGRICULTURE. 


= 


were killed by the parasite. The other trees in the figure show — 


various stages of suppression and an abnormal thinness of foliage. 


The tree on the extreme right shows midway on its trunk a typical 
mistletoe trunk burl. 

It is often disputed that mistletoe is a cause of spiketop or that 
it is totally unknown for some species. The first and heaviest seat of 


infection in nearly all trees of economic importance is in the lower’ 


part of the crown (figs. 6 and 8). This is not necessarily a result of 
the seeds of the parasite falling first on the lower branches, but is 
rather the result of the fact that the main shoot continues for a time 
to grow in height, and the crown may attain its normal height be- 
fore the effects of the parasite become dominant. The mistletoe 
spreads upward from the lowermost branches, with the result that 
the more recently formed branches are continually being infected. 
That these infections may not cause a brooming of the branches in 
the beginning is abundantly shown by the entire absence of any 
brooming on young infected branches of several host species. This, 
however, is only the first stage in the hypertrophy of the branch. 
_ After the lapse of several years, typical brooms are formed. With 
the increasing hypertrophy of the lower portion of the crown, food 


materials are more and more appropriated at this point. The result | 


is a drain on the resources of the entire tree to support the brooms. 


Materials traveling upward from the roots are likewise utilized by — 


the broomed branches, with the result that the upper portion of the 
crown starves and in cases of severe infection finally dies (figs. 5, 6, 
7, and 8). Spiketop is an almost universal condition in heavily 
infected larch. The tendency to form spiketop in this species, how- 
ever, is greatly augmented by the brittleness of its branches. Douglas 
fir probably comes next in order of frequency of dead tops resulting 
from the growth of mistletoes. The condition is common for yellow 
pine in all regions where observations have been made by the writer 
and is reported to be of frequent occurrence by correspondents in 
Utah and Wyoming. Lowland and mountain hemlocks, when heavily 
infected, quite commonly exhibit dead tops. An unusual case of 
heavy infection of the former species was studied in the St. Joe 
National Forest. Practically every tree in the entire stand was dead 
in the top (fig. 9). Lodgepole pine is less affected in this manner 
than any other conifer so far. studied by the writer except spruce 
and fir. The last-named species are so seldom infected, however, 
that they would not enter into the discussion. 

There can be little doubt that spiketop is very often the result 
of heavy mistletoe infection, but varies in degree for the several 
hosts. This condition is of importance, since the proportion of 
snags in the stand is thereby increased, which may promote injury 
by fungi and insects; it also increases danger from lightning fires. 


MISTLETOE INJURY TO CONIFERS. 13 


With the conclusion of this general statement of mistletoe injury 
a more detailed discussion of the various types of infection will 
now be taken up. 


RESULT OF INFECTION ON THE BRANCHES. 


— One of the first effects of infection, either of stem or branch, is 
- the formation of a fusiform swelling (fig. 10). Sometimes this 
swelling is very pronounced and may resemble the enlargements 
- caused by some species 
of Peridermium (fig. 
11). The swelling is 
the first stage of the 
future hypertrophy 
commonly known as 
witches’-brooms. The 
absence of any pro- 
nounced brooming 
from early infections 
has led some observers 
to the conclusion that 
brooms are never pro- 
duced on some conifers. 
Any change from the 
normal branching is 
here considered a 
broom. Still it is not 
necessary to draw such 
sharp lines, as the 
brooms produced by all 
mistletoes of the genus 
in question are quite 


typical. It may re- Fic. 9.—Western hemlock (T'suga heterophylla) infected 
quire several years for by Razoumofskya tsugensis. These trees do not possess 

a single normal branch. All are broomed. The trees in 
the broom to form. Ef the background are spike topped. The tree in the fore- 


ts ground has had its growth in height arrested by an 
young trees are sen immense terminal broom. 


erally infected they 

sometimes assume an open, ragged appearance, which to the casual 
observer would not be considered a broom (PI. III, fig. 2). Never- 
theless, the tree is no longer excurrent. A similar condition is 
sometimes noted in more mature larches, where the infection is so 
_ generally distributed throughout the entire crown that no typical 
_ brooms are produced for years. Heavily infected branches of old 
trees of all species are seldom without brooming of some kind, and 
in most cases typical brooms are formed. The mistletoe plant may 
die out entirely on very old brooms, especially those of yellow pine 


14 BULLETIN 360, U. S. DEPARTMENT OF AGRICULTURE. 


(fig. 12), but the stimulus to abnormal branching may continue. 
Brooms are formed on all hosts attacked by this genus of mistletoe. 
Those of the yellow 
pine, owing to their 
loosely branched con- 
dition (fig. 12), are 
sometimes not as con- 
spicuous as those pro-— 
duced on Douglas fir~ 
(figs. “6,°"T, aan 
larch (fig. 14), hem- 
lock (fig. 9), or lodge- 
pole pine. 

In all the regions 
where the yellow-pine 
mistletoe has been ob- 
served in the States of 
Washington, Oregon, 
Idaho, Montana, and 
South Dakota, broom- 
ing is a common result 
of the growth of’ the 


Itc. 10.—Young, first infections of Razowmofskya cam- parasite on this tree. 
pylopoda on western yellow pine (Pinus ponderosa). Correspondents ak W 


oming, Utah, and Colorado report that old infected trees are seldom 
without them. MacDougal (8)? refers to the excessive brooming of 
yellow pine by mis- 
tletoe in the South- 
west. Meinecke (10) 
refers to the very 
conspicuous brooms 
on Jeffrey pine, 
sugar pine, yellow 
pine, lodgepole pine, 
and Douglas fir. 
The old brooms of 
the Douglas fir, be- 
cause of the long, 
trailing, willowlike 


i | f | Fic. 11.—A larch branch, showing the result of a first infec- 
ranches of the tion at its base by Razouwmofskya laricis. ‘This is the be- 
lower portion of the ginning of a burl at this point, which will spread to the 
main trunk. y 
broom, are more con- 
spicuous than those of other conifers (fig. 13). They sometimes 


attain an immense size, often including the entire crown (fig. 6). In 


1 Reference is made by number to “ Literature cited,” p. 89. 


MISTLETOE INJURY TO CONIFERS. 15 


most cases brooms are initiated on the Douglas fir soon after infec- 
tion. Young seedlings frequently die in the top, owing to the forma- 
tion of a lateral broom midway on the stem. In the heavily infected 
regions of Montana, especially in the Clark Fork (Bitterroot and Mis- 
- soula Rivers) drainage, brooming of the Douglas fir is so universal 
and of such extent that scarcely a single infected tree is free from 
brooms of some type (figs. 6 and 7). The structure of these brooms 
is very plainly shown if the tree succumbs to the parasite, as it often 
does (fig. 7). The formation of brooms invariably results from mis- 


tletoe infection on 
the western larch. 
They may be situ- 
ated on any part of 
the branch or at its 
base (fig. 14). In 
the latter case the 
entire branch even- 
tually dies or is 
broken off by the 
. wind, and its place is 
usually taken by a 
Series of short, 
scrubby secondary 
branches forming a 
trunk broom. This 
broom eventually 
_ dies, leaving a large 


knotty burl of seri- Fig, 12.—Typical broom on yellow pine caused by Razou- 
ous consequence not mofskya campylopoda, Note that the end of the branch 


only to the life ofthe bane 
_tree but greatly decreasing its value for lumber. Excessive brooming 
isa common feature wherever infected larch occurs and is the chief 
cause of injury to the species. In some localities in the Blue Moun- 
tains of Oregon and parts of Idaho and Montana, where this mistletoe 
Is common, a normally formed larch is seldom found. Instead of the 
symmetrical, conical crown so characteristic of the normal tree, the 
crown develops under the influence of the parasite into a denuded 
spike, bearing only a few ragged branches. When it is recalled that 
_ practically every larch in these regions, from pole size up, is more or 
less infected and seldom attains a normal size, in many cases being 
killed outright, some notion may be had of the seriousness of the 
effects of the parasite on its host. 


gation 


=; = 
Dy Df Ris 
. 


16 BULLETIN 360, U. S. DEPARTMENT OF AGRICULTURE. 


The brooming of the branches of the lodgepole pine by mistletoe is 
as characteristic as for the other hosts mentioned. Frequently the — 
entire tree is involved, 
but more often only 
the lower branches. A 
few instances have 
been noted where the 
parasite hung in long 
festoons from the sev- 
eral infected branches 


Fic. 13.—Typical broom of the weeping-willow type on Doug- 
las fir caused by Razoumofskya douglasii. Note the long, 
flowing branches. Sometimes these branches are 8 to 10 
feet long. 


without any particular hypertrophy of the 
branch asa whole. This condition is more apt 
to occur in dense stands. Observations by the 
writer on Picea engelmanni, P. mariana, 
Abies grandis, A. lasiocarpa, A. concolor, A. 
magnifica, Tsuga heterophylla, T. merten- Fic. 14.—Typical brooms of old 
. . . ° < ae infections on western larch 
siana, Pinus monticola, P. albicaulis, P. jleti- caused by Buse 
lis, P. attenuata, and other conifers show that cis. Very few of the origi- 
° : nal branches remain, and 
brooming of the br anches is a common phe-  iney are heavier 
nomenon attending mistletoe infection of covered with lichens. The 


tl old branches are replaced by 
1ese species. short scrubby secondary 


The weight of these brooms on many coni- _ Pranches. Note that two of 
f ‘exobbict bias ails aint a 1 f the original branches still re- 
ers is frequently suilicient under stress o main’ ‘burt Wee aeae 
winds and rain to cause the branches to split 
from the trunk, or to break farther out if the brooms are located far 
out from the trunk. This very commonly occurs in the case of 


MISTLETOE INJURY TO CONIFERS. oe 


yellow pine and Douglas fir (fig. 15) and is the rule for larch. The 
stunting effect of these brooms on the trees as a whole was in one 
instance very interestingly shown by the fact that a middle-aged 
Douglas fir increased the radial dimensions of its annual rings after 
the removal by the wind of an immense broom located midway on 
the trunk. The weight of the brooms on some conifers is very often 
greatly increased by the accumulation of dead needles, lichens, ete. 
(fig. 14). When loaded with snow or saturated with moisture the 
brooms are more 
easily broken off by 
high winds. . The 
ground around the . 
base of heavily in- 
fected larches is very 
frequently littered 
with brooms broken 
off in this manner, 
often insuring the 
death of the -tree in 
ease of ground fires. 
During the early 
part of October, 
1914, an unusually 
heavy fall of soft 
snow occurred locally 
over a small area 
around Missoula, 
Mont. The snow ac- 
cumulated in such 
quantities on the mis- 
tletoe brooms of the Fic. 15. 
larches and Douglas 
firs throughout the 
area that the ground around the more heavily infected trees was piled 
high with fallen brooms. 

The foliage of old and mature mistletoe brooms is usually not 
as long lived as that of normal branches of uninfected trees. This 
is not true in the case of young well-nourished brooms. It has 
been observed to any extent only in old brooms which have begun 
to tax the food supply of the tree or the branch on which they are 
located. In the course of one year it was determined that 655 more 
needles fell from a small but mature broom on a Douglas fir than 
from a normal branch of a neighboring uninfected tree of the same 
species. The number of needles falling from the broom totaled 

24182°—Bull. 360—16——3 


Fallen brooms split from the trunk of a Douglas 
fir and piled about the base of the tree—a serious fire 
menace, 


18 BULLETIN 360, U. S. DEPARTMENT OF AGRICULTURE. 


976, from the branch 321. On very old brooms of the western larch 
it is often noticed that the needles begin to turn yellow some time 
before those on the branches of uninfected trees. Exactly the re- 
verse may occur in the case of recently formed brooms, owing to 
the larger amount of newly stored food materials in the swelling 
on the main branch and the branches of the brooms. That the 
broom may be the cause of a great localization of food substances 
is indicated by the fact that in heavily infected Douglas fir and 
larch the last part of the tree to succumb is usually the smaller and 
younger brooms of the tree. Frequently trees of these species are 
noticed with only a single small broom living, the rest of the branches | 
being apparently dead; likewise the old and exhausted brooms. The 
increase in the number of needles on the broom due to the multi- 
plication of its branches is usually at the expense of the needle de- 
velopment on the normal parts of the tree. For this reason an 
excess of food materials for the tree as a whole does not take place. | 


The foliage beyond the broom becomes thin and, in most cases, _ 


the end of the branch dies (figs. 12 and 14). The food materials 
are entirely stored and appropriated by the broom: itself. The 
phenomenon is analogous to the formation of spiketop of the main 
trunk. | . 
That brooms do not always necessarily mean an increase in foliar 
surface for the host, since we have seen that parts of the branches 
not supporting brooms frequently die, is shown by a comparison of | 
the needles of old brooms with those of normal branches either of 
the same tree or of uninfected trees. Such a study was made in the 
case of the Douglas fir. It was found that the needles of the brooms 
on the trees studied were uniformly a little less than one-half as long 
as the leaves of the normal branches (PI. IV, fig. 1). Neither were 
they as thick or as broad. By compensation it would be possible to 
determine approximately the actual foliar surface of a given broom 
and compare it with that of a given normal branch of the same 
whorl and of the same age. This difference in the size of the needles 
was found to hold good only in the case of old, mature brooms of trees 
which were beginning to be suppressed. Young brooms, especially 
on young trees from 10 to 20 years old, often have abnormally long 
needles on the still upright branches, but this condition is not long 
maintained. Soon these branches begin to droop, the broom be- 
comes denser, the needles disappear from the center outward, and 
they are often sparingly distributed along the stems but more densely — 
assembled on the last few years’ growth (fig. 13). With continued 
suppression of the Douglas fir and exhaustion of the broom, a new 
type of branching often appears. The long trailing, weeping-willow- 
like branches cease to elongate and the cortical stroma of the parasite 
is enabled to catch up with the terminal bud and kill it. The branch 


MISTLETOE INJURY TO CONIFERS. - . 19 


ceases to grow in length and instead forms abnormally abundant 
lateral branches. The terminal buds of these are likewise overtaken 
_ by the parasite, resulting in additional lateral branches, and so on, 
until a type of dichotomous branching results. This is more notice- 
able in the compact type of broom than in the long, trailing type, but 
is quite common in both, especially on exposed and wind-swept areas. 

A very interesting hypertrophy of the foliage spurs is often 
shown by the brooms 
of the larch. The 
spurs are frequently 
abnormally large 
and may be four or 
five times as long as 
those of normal 
branches (fig. 16). 
On such spurs the 
needles are usually 
shorter and spar- 
ingly clustered. 
Eventually the para- 
site enters the spur 
and kills it. Not in- 
frequently a mistle- 
toe plant is found 
growing out at the 
apex of the spur or 
from its side, caus- 
ing great distortion 
and the total disap- 
pearance of the nee- 
dles, and eventually 
_ the death of the spur. 


The reduction of Fic. 16.—<Abnormal foliar spurs of the western larch caused 


foliage by the thin- by Razoumofskya laricis. Note their size as compared 
J : with normal spurs. 
ning and shortening 


of the needles of the trees as a whole, and of the brooms sooner or 
later, is characteristic of mistletoe infection on all hosts. 

The food material, which undoubtedly is accumulated in the 
brooms, seems to be entirely appropriated at these points and does 
not serve the host as a whole. The support of the excessive number 
of branches is necessary, but the parasite itself undoubtedly appro- 
priates a large share at the expense of the healthy branches. The 
_yellow-pine mistletoe has been observed to become more luxuriant 
and to develop abnormally long stems on swellings which had been 
lacerated or gnawed by rodents. Evidently the accumulation of 


20 BULLETIN 360, U. S. DEPARTMENT OF AGRICULTURE. 


beneficial influence on the parasite. | 

The actual nutritive relation between these parasites and their 
hosts is not at present well understood. The constant removal of 
all the needles of six lodgepole pines 8 to 12 years old on which 
large clumps of mistletoe were attached has not in the second year of 
the experiment resulted in the death of either the host or parasite. 
The controls, viz, six young pines of the same age, stripped of their 
needles but bearing no mistletoe plants, have died. This experi- 
ment indicates a possible transfer between the host and parasite not 
only of water and inorganic salts, but of or- 
ganic food materials as well. However it 
may be interpreted, it seems that the pines 
were kept alive temporarily by the mistletoe. 
Probably it is a mutual subsistence on stored 
materials. It must be remembered that the 
whole tendency of the activities of these mis- 
tletoes (azoumofskya spp.) is to reduce the 
life functions of the host to their lowest 
point, and this is the fact that should be of 
chief concern to the forester. 


RESULT OF INFECTION ON THE TRUNK. 


Another form of mistletoe injury results 
when infections occur during the early life 
of the tree, with the formation of burls on 
the trunk. No case is on record of any mem- 
ber of the genus Razoumofskya effecting an 


Fic. 17.—Area on the main 
trunk of a yellow pine 
infected by Razoumofskya entrance to its host through the mature cor- 


campylopoda. The rough, 2 3 
frregulat hak sadicabsdine ee If apparently recent infections on old 


location of the burl tis- parts of trees are carefully examined, the 
sues. A few short mistle- : er ts 
Cie lactase oe eae mistletoe plant will be found to have per 
the illustration were pres- sisted from the time when the branch or 
vent trunk was, young. Until it is proved by 


actual inoculation that the parasite is able to penetrate the mature 


cortex with its outside covering, commonly called the bark, the fore- 


going statements must remain valid. 


Burls on the trunk caused by mistletoe are very common for 


some hosts, but vary in frequency on others. In point of frequency — 


the western larch is most seriously affected by this kind of injury. 


Two types of burls occur on this tree, determined by the nature of 
the original infection. If the infection occurs at the base of a 
branch (fig. 11) and travels to the main trunk, a basal branch burl 
results, giving rise to a broom, which later dies, leaving a great burl, 
often of large proportions. If infection occurs directly on the main 
trunk the beginning of a trunk burl is immediately initiated. With 


ail 


extra food materials in the healing tissues at this point exercised a 


. oF cca ay Pon ee 


4 oat ag PE Ly 


pe Sf ae Sarantis te ih v 


on yly Gears 


MISTLETOE INJURY TO CONIFERS. 21 


the increasing age of the host the burl tissues radiate outward in a 
fan-shaped area when viewed in cross section and soon leave an open 
wound, through the death of the central part of the infected wood. 
These two types of burl are so common on larch in mistletoe regions 
that the quality of the wood is seriously injured, resulting in a 
large amount of cull: In the several regions studied by the writer 
mistletoe burls on yellow pine are frequent. In one section of the 
city park at Coeur d’Alene, Idaho, are 30 or 40 large, old yellow 
pines. About half of the trees have mistletoe burls on the first 


Fic. 18.—Cross section of a mistletoe burl on the yellow pine shown in figure 17. 
(The tape shows feet in tenths.) 


log length and in most cases the parasite is still living in them, 
with a few scattering short aerial parts. Similar conditions pre- 
vail throughout the Spokane River Valley and around Coeur d’Alene 
Lake. Mistletoe burls on old yellow pine may or may not be con- 
spicuous. Frequently there is no pronounced swelling (fig. 17) and 
sometimes the only means of detecting the diseased condition is by 
the presence of the mistletoe or an unusual roughness of the bark. 
A section through the tree at this point, however, shows the curly 
grain and the old roots of the parasite extending to the point of 
original infection (fig. 18). These burls are often very conspicu- 


22 BULLETIN 360, U. S. DEPARTMENT OF AGRICULTURE. 


ous, large barrel-shaped swellings, from which pitch usually exudes 
in large quantities. Infection on one side of the tree generally re- 
sults in the type of burl shown in 
figure 19. 

Burl formations resulting from 
mistletoe are a common feature 


Fic. 19.—Common type of burl on yellow 
pine caused by Razowmofskya campylo- 
poda. The tree is 8 feet in diameter at 
this point. 


H 
3 
i 
4 
4 
4 
: 
2 
a 
4 
4 
: 
: 
4 
: 
4 
: 
fq 


on western hemlock wherever the 
parasite occurs in quantity. The 
same is true for the mountain 
hemlock. In the Marble Creek 
region of the St. Joe National 
Forest mistletoe burls on the 
hemlock are of frequent occur- 
rence. Allen (1, p. 20-21) writes 
of this type of injury as follows: 
“Tf, however, the plant gets 
foothold on the leading shoot, a 
burl follows which persists 
throughout the lfe of the tree 
and not only ruins a log, but ren- 
ders the tree apt to be broken by 
the wind.” Infection on the main 
trunk of lodgepole pine is often 

attended by long fusiform swell- Pe,205,Main stem of a 1odgepote ping tn 


ings as the parasite progresses the spread of the parasite from the original 
fe bh eal ; 7 point of infection. The bark at this point 
rom the origina point OI 1N- very frequently dies, leaving an “open wound. 


fection. This may continue until (Photographed by George G. Hedgcock.) 
the bark becomes so hard that the plants can not push up through 


it and the spread of the parasite ceases (fig. 20). The parts. 


orm 


ee ee 


MISTLETOE INJURY TO CONIFERS. 93 


infected, however, may continue to produce aerial branches of the 
‘mistletoe to a very advanced age. True mistletoe burls are probably 
of less frequent occurrence on Douglas fir than on any other economic 
tree species. Burls do occur, however, with sufficient frequency to be 
characteristic of mistletoe infection on the trunk of this tree. Large 
elongated mistletoe burls, including the entire circumference of the 
trunk, occasionally occur in heavily infected trees in many parts 
of Idaho and Montana (fig. 21). More frequently there is a,series 


4 
4 
] 
: 


Fic. 21.—Large mistletoe burl on Douglas fir FIG. 22.—A Douglas fir, showing numer- 


caused by Razouwmofskya douglasii. This ous burls caused by Razoumofskya 
burl is approximately 10 feet long and 2 douglasit. The branches are heavily 
feet in diameter at its widest part. broomed. A high degree of infection, 


but a common condition, is shown. 


of individual burls, more or less confluent, on one trunk (fig. 22),. 
each burl representing the seat of an old infection, from which the 
aerial parts of the parasite have long since disappeared. Longitu- 
dinal and cross sections through these burls show the characteristic 
fan-shaped areas of infection (fig. 23). In numerous cases the burls 
originate from infections at the base of branches. If the branch 
dies or is broken off, an open wound is formed in the center of the 
burl. Very peculiar swellings or small burls frequently occur on 


24 BULLETIN 360, U. S. DEPARTMENT OF AGRICULTURE. 


the branches of brooms. These are sometimes so numerous as to 
cause the branch to resemble a chain of spherical balls. Mistletoe 
infection on the trunks of spruces in the East often results in the 
formation of burls; also on the western firs. It can be safely stated 
that swellings and distortions of the main trunk which persist 
throughout the life of the tree are a characteristic feature of mistle- 
toe infection on most conifers of economic importance. 

The spread of the burl tissues tangentially and longitudinally, 
which, as previously indicated, are frequently inhabited by the 


Fic, 23.—Cross section of one of the burls on the Douglas fir shown in figure 22. This 
section does not pass through the point showing the age at which the infection first 
occurred. (The tape shows feet in tenths.) 


parasite until a very advanced age,! results, as is the case with most 
species, in cutting off the transporting tissues and hastens the de- 
cline of the tree (figs. 20, 23, and 24). The bark and wood of the 


1 Meinecke, in 1912 (9, p. 38), records the age of a mistletoe plant (Phoradendron 
juniperinum libocedri Engelm.) at approximately 230 years. Species of the genus Razou- 
mofskya are likewise capable of maintaining themselves to a very advanced age. One 
instance recorded by the writer may be cited of Razoumofskya campylopoda. <A cross sec- 
tion through a mistletoe burl of this species, 3 feet from the ground, on yellow pine—a po- 
sition precluding any but an original infection at an age when the bark was thin—showed 
that the parasite had continuously lived in the burl tissues for 340 years. The old roots, 
now dead except those immediately next the cambium, could be readily traced to the point 
of original infection The age of the tree at this point was three years. The burl bore a 
single fertile aerial branch of the mistletoe. The greater mass of the cortical stroma 
was entirely without aerial parts, indicating the remarkable condition of parasitism first 
pointed out by Meinecke for Phoradendron juniperinum libocedri. 


MISTLETOE INJURY TO CONIFERS. 25 


outer central area of the burl die soon after the death of the cor- 
tex, especially in burls on the larch, and open wounds are formed, 
inviting the attack of forest-tree insects and wood-destroying fungi 
(fig. 24). The abnormal thickness and the soft, spongy consistency 
of the inner bark of mistletoe-infected branches are attractive to 
various gnawing animals; they are also an index of the storage of 
food materials at this point (fig. 25). 


Fic. 24.—Cross section of a burl on a western larch caused by Razoumofskya laricis. 
Diameter of burl, 2 feet. Note the presence of borers.and fungi. The check ap- 
peared in seasoning. 


RELATION OF MISTLETOE INJURY TO FUNGOUS ATTACK. 


Some very interesting data have recently been assembled by the 
writer on the relation of mistletoe burls to fungous attack. From 
cutting areas on the dry bench lands of northern Idaho, 540 mistle- 
toe-infected living larches were examined. Out of 600 mistletoe, 
burls found on these trees, 278 were inhabited by serious wood- 
destroying fungi and other unimportant species. According to 
frequency of occurrence the most important of these fungi are 
Trametes pint (Brot.) Fr., Fomes laricis (Jacq.) Murr., Polyporus 
sulphureus Fr. (four occurrences at 20 feet up on the trunk, a very 


°6 BULLETIN 360, U. S. DEPARTMENT OF AGRICULTURE. 


unusual habitat), Zrametes serialis Fr., and Lenzites sepiaria Fr. 
Fomes pinicola Fr. was found rotting the heartwood of living trees 
in three different cases and had entered its host through mistletoe 
burls 10 feet from the ground. Polyporus volvatus Pk. occurs fre- 
quently on the burls of larch and yellow pine. Several species of 
Thelephoracex were collected from the mistletoe burls, chief of which 
were Stereum sulcatum Burt, 
Corticium berkeleyi Cooke, 
C. galactinum (Fr.) Burt, 
and Peniophora subsul- 
phurea (Karst) Burt. Cera- 
tostomella pilifera (Fr.) 
Wint., the bluing fungus, 


dead wood of the burls. 


by fungi. Since the most 


were always at the burl or in 
its near vicinity, it was as- 
sumed that the fungi had en- 
tered at this point. The de- 
cay at or in the burl tissues 
was in most cases not con- 
nected with the decay which 
is often present in other 
parts of the trunk. The 
breakage of old branches 
possessing heartwood, 
through the accumulation of 
brooms at their outer ex- 
tremities, is likewise a means 
of fungi entering the tree. 


Fic. 25.—The soft spongy cortex of a mistletoe 
infection on lodgepole pine gnawed by rodents. 


This is a very common type of injury in mistle- Not infrequently Fomes 


toe-infected trees. a : ° 
laricis enters its host by this 


means. Mistletoe burls on Douglas fir are known to become infected 
with 7rametes pini. A mistletoe burl on Alpine fir was found to be 
inhabited in one instance by Pholiota adiposa Fr. Meinecke (10, p. 
58) refers to the mistletoe cankers of Abies concolor as offering an 
easy entrance to germinating spores of H'chinodontium tinctorium. 


Burls on yellow pine, owing to their resinous condition, are seldom 


attacked by wood-destroying fungi. The bluing fungus, however, 
has been found by the writer in the distorted tissues of mistletoe 
burls on living yellow pine. 


appeared occasionally in the 


advanced stages of decay 


Trametes pini affected 80 
per cent of all burls attacked © 


MISTLETOE INJURY TO CONIFERS. ae 


GENERAL SUPPRESSION AND FUNGOUS ATTACK. 


Aside from the fact that fungous enemies enter these conifers 
- through broken branches, lesions, and burls caused by mistletoe, 
heavily infected trees are, owing to their weakened condition, more 
susceptible to fungous attack on any part—roots, trunks, or leaves. 
_ In the lake region of Idaho the larch of all ages and conditions is 
at present suffering from an epidemic of a needle disease, Typoder- 
mella laricis Tub. It is observed that in practically every instance 
the needles of very old mistletoe brooms are first attacked, whereas 
those of the uninfected trees of particular age classes or exposures 
may ward it off for a longer period.t It is a common observation 
that in regions of heavy mistletoe infection (and nowhere is it better 
shown than in the forests of eastern and central Oregon and many 
parts of Idaho and Montana) many heavily infected trees are in 
a dead and dying condition. If these trees are carefully examined 
with reference to average healthy growth for the region, it will be 
found that they have died prematurely. — 

It has already been indicated that mistletoe is capable of causing 
the death of its host in some instances. The whole tendency of the 
_ parasite is to reduce the life functions of its host to the lowest point, 
_ and if death does not result from this cause alone the way is opened 
_ to various secondary agents, which may or may not attack vigorously 
- growing trees. The gradual thinning out of the foliage of heavily 
infected trees and the appropriation by the brooms of much of the 
elaborated food materials must necessarily result in an unbalanced 
relation between the crown and the root system. Consequently, there 
may be a dearth of food materials for the latter, wholly inadequate 
to support its present extent. It may be naturally inferred that this 
results in the suppression of the roots or a dying off of the more 
extended members of the system. A close examination of a hundred 
or more windfalls of heavily infected Douglas fir, yellow pine, and 
larch in the regions above mentioned shows quite clearly that the 
horizontal and brace roots of these trees in most cases were badly 
decayed. Since few windfalls of the heavily uninfected trees of 
the same average age and size were observed in the same region, 
it may be inferred that a possible relation existed between the sup- 
pressing effects of the mistletoe and the decay in the roots. Armil- 
 \laria mellea (Vahl.) Quél. was definitely associated with some of 
_ the decay in the roots. In most cases, however, owing to the absence 
of fruiting stages, the cause of the rot in the fallen trees could not 
be determined. 


Se) ee eee 


 1Hypodermella laricis was first named and described by Von Tubeuf on the European 
larch (Larix europaea). This is the first note of its occurrence in North America. The 
fungus, characterized by its four clavate spores to an ascus, is very destructive and is the 
eause of considerable damage in the larch forests of the northwestern United States and 
Canada. 


28 BULLETIN 360, U. S. DEPARTMENT OF AGRICULTURE. 


It is a well-known fact that wounds heal quickly in young or in 
strongly growing trees, principally due to the protection afforded by | 
an abundant flow of resin. It may be assumed that trees having their — 
hfe functions brought to a low ebb by excessive mistletoe infections, 
with resulting decrease in annual increment, will not be able to heal 
or protect their wounds as quickly as normal trees; hence, are more 
liable to infection. This may be one of the reasons why so many 
open burls are formed on infected larches. These open burls are 
seldom, if ever, healed, although the parasite in its tissues has long 
since died. There is a slight increase in the number of resin passages 
in early burl formations, but this is entirely offset by the early dying 
out of the bark of the burl exposing the wood. It is an observed fact, 
experimentally proved by the writer, that strongly suppressed yellow 
pine, larch, and Douglas fir do not as readily form traumatic wood 
or exude the normal quantity of resin on being wounded on any part 
as do normal, healthy trees. Such a tardy reaction to injury does not 
afford a ready antisepsis against the entrance of fungi which may 
attack these trees. Since turpentine orcharding is becoming more 
extensively practiced in the West it would be an interesting experi- 
ment to determine the relative flow of pitch from trees strongly sup- 
pressed by mistletoe and from those in a high state of health. . 


RELATION OF MISTLETOE INJURY TO INSECTS. 


In the same manner that burls and other types of mistletoe injury — | 


on some conifers are open doors to fungi, they are found to afford 
a ready means of entrance for some species of forest-tree insects 
which do not in this region habitually attack vigorous unwounded 
trees. Old mistletoe burls on larches are almost invariably attacked 
_ by borers (figs. 23 and 24), and burls on yeliow pine are, in the ex- 
perience of the writer, quite as frequently infested by bark and wood 
boring beetles. In this connection a very curious and interesting phe- 
nomenon often occurs on young yellow pines from 10 to 20 years 
of age. An infection by mistletoe will have occurred, completely 
enveloping the trunk some 2 or 3 feet from the ground. The parasite 
having advanced somewhat each way.from the point of original 
infection, the intervening space is attacked by Dendroctonus valens 
Lec. The combined influence of the beetle and mistletoe results in the 
complete infiltration with resin of the space between the two edges 
of the advancing mistletoe, so that the cambium dries out and dies. 
Strange to state, this does not always kill the tree. The crown goes 
on manufacturing food materials, being supphed with water through 
the inner wood of the girdled area. The elaborated food not being 
able to travel downward, since the cambial tissues of the entire cir- 
cumference of the stem have been destroyed, is stored just above the 


MISTLETOE INJURY TO CONIFERS. 29 


girdled area and initiates an abnormal swelling (fig. 26). The swell- 
ing continues to increase in size and weight, likewise all members of 
the crown, so that eventually the slender stem below can no longer 
support the overdeveloped crown and is broken down by the wind. 
A specimen in the laboratory shows the number of rings of the stem 
at the girdled area at the time it was cut to be eight, with a diameter 
of 1 inch. The swelling just above and within the same internode 
showed 15 rings, with a diameter of 3 inches. The same phenomenon 
is sometimes produced in yel- 
low pine by Peridermium fila- 
mentosum Pk. When it is re- 
called that the cambium and 
the outer wood of the girdled 
area are actually dead, the 
length of time the crown con- 
tinues alive is really remark- 
able. 

In point of general insect at- 
tack it has been noted that the 
beginning of an infestation 
may start with trees badly 
suppressed by mistletoe. The 
fact that trees heavily sup- 
pressed by mistletoe have a 
weak flow of sap causes them 
to be first selected by certain 
forest-tree insects. For this 
reason mistletoe areas form 
centers from which infesta- 
tions may spread. Again, nu- 
merous infestations may start 
simultaneously over a wide 
territory, owing to the weak- ric. 26.—a young yellow pine, showing com- 
ening of the trees by these par- plete girdling of the stem by a combined at- 

, . tack of mistletoe and insects. The cambium 
asites instead of from a few is destroyed, but the crown remains alive and 
detached areas, as is often the continues to elaborate food materials, which 

* are stored just above the girdled area. 

case. This has been found par- 

ticularly true in the case of yellow pine and the red turpentine beetle 
mentioned above. In all regions of heavy mistletoe infection of the 
Douglas fir, Dendroctonus pseudotsuga Hopk. is usually very abun- 
dant. This was the rule in the Whitman National Forest, Oreg., and 
though the numerous dead trees of this species in the forest. were 
undoubtedly the result of an immediate attack by the beetles, their 
work was hastened, it seemed, by the serious mistletoe suppression 
which was exhibited by most of the dead trees. During the season 


30 BULLETIN 360, U. S. DEPARTMENT OF AGRICULTURE. 


of 1914, a large number of badly suppressed Douglas firs on the foot- 
hills bordering the Clark Fork (Missoula River) Valley have died 
from a combined attack of mistletoe and beetles. Most of these trees, 
which supported scarcely a single normal branch, had the bark of 
limbs and trunk almost entirely removed by woodpeckers in their 
search for the beetle before the leaves were entirely dead. The few 
uninfected Douglas firs of the same region have not been attacked by 
the beetles. 

The branches of large mistletoe brooms on yellow pine and Doug- 
las fir from which the parasite has entirely disappeared are very 


Fig, 27.—Seats of original mistletoe infection on-two living branches (in center and at 
left) of mistletoe brooms on yellow pine infested with bark beetles. No other part of 
the broom or tree was attacked. Main stem of young living yellow pine (at right) 
attacked by bark beetles at the seat of an old mistletoe infection. 


frequently found infested with bark beetles (fig. 27), while the trunk 
and normal branches of the trees are entirely free from attack. 


INFLUENCE OF MISTLETOE INJURY ON THE SEED PRODUCTION 
OF THE HOST. 


Germination tests of seeds of yellow pine taken from mistletoe- 
infected trees show that the percentage of germination is consid- 
erably lower than is the case with seeds taken from normal trees 
(12, p. 7). Experiments conducted by the writer with seeds taken 
from cones produced on very old mistletoe brooms of Douglas fir, 
larch, and lodgepole pine showed a germination on an average of 
10 per cent below that of seed taken from uninfected branches of 


eel en oe ot a ele es re 


, 


- 


MISTLETOE INJURY TO CONIFERS. ol 


the same trees. Given the general average percentages of germina- 
tion of 30 for the former and 40 for the latter, it seems that either 
from exhaustion of stored materials or tendencies toward abnormal 
seed production in general the uninfected branch, though suppressed, 


is still capable of producing a higher quality of seed than the broom. 


Whether this would be true in the case of young, vigorous brooms 
is doubtful. Seeds from the uninfected branches of the same 
strongly suppressed trees used in the above experiment gave a gen- 
eral average of 15 per cent below that of seeds taken from vigorous 
uninfected trees of the same age, species, and habitat. The per- 
centage of 65 for the uninfected and 40 for the infected shows quite 
clearly that suppression by mistletoe causes a serious falling off in 
the quality of the seed of its host. 

The experiment was conducted in the following manner. Col- 
lections of cones were made from each of five strongly suppressed 
and five uninfected trees of all three species. This included one col- 
lection from the brooms, one from the uninfected branches of each 
of the suppressed, and one collection from each of the uninfected 
trees; in all, 45 different collections. One hundred seeds were ex- 
tracted from each collection and germinated in sand at an average 
temperature of 35° C. Counts were made at different intervals dur- 
ing the progress of the test, which was continued for 90 days. Con- 
siderable difficulty was experienced in procuring the required num- 
ber of seeds for all conditions, owing to the sterility of the cones 
on the old brooms. With the increasing age of the broom the seed 
production falls off, until, as it is with most species, no cones are 
produced at all. Seeds from recently formed brooms were not tested. 
It is supposed that they would show a higher percentage of germi- 
nation. The cones on badly suppressed trees are very often aborted, 
with shriveled, undeveloped sporophylls, and are frequently infested 
by cone beetles and cone worms. Seeds, if produced in such cones, 
are usually below the normal size. A study of microtome sections 
of the staminate flowers from heavily infected lodgepole pine showed 
that there was a reduction in the number of pollen mother cells. The 
staminate flowers when compared with those of normal trees of the 
same age and condition were found to be uniformly smaller. The 
sporophylls on the more fertile or convex side of the young pistil- 
late cones very frequently bore only one ovule (megasporangium), 
a condition not observed in cones from healthy trees. 


HOST AFFINITIES IN RELATION TO SILVICULTURE. 


For practical purposes the following statements on the host re- 
quirements of the mistletoes of coniferous trees will be found to 
be of some interest with regard to the silvicultural management of 
forests. ! 


32 BULLETIN 360, U. S. DEPARTMENT OF AGRICULTURE. 


Razoumofskya douglasiit (Engelm.) Kuntze is of economic impor- 


tance only on the Douglas fir. The affinities of the very small and rare 
forms of Razoumofskya on spruce and fir,’ described by Engelmann 
(6, p. 253) under the name of Arceuthobiwm douglastii var. micro- 
carpum for the former host and A. douglasii var. abietinum (3, v. 2, p. 
106) for the latter, are not definitely established. In point of time of 
blooming and seed maturity, it coincides with that of Razowmofskya 
douglasti for northern regions, and their form and color are quite 
similar, especially the color of the staminate flowers. These small 
plants, together with the Douglas fir mistletoe, are the only mem- 
bers of the genus exhibiting a pronounced color of the lobes, which 
are a bright, deep purple. Until cross-inoculation experiments are 
perfected, these particularly small mistletoes on spruce and fir may 
be considered wholly unimportant from a silvicultural standpoint. 
For the sake of convenience, they may be placed with the Douglas 
fir mistletoe and the whole designated as the Pseudotsuga-A bies- 
Picea group, characterized by their small size and colored flowers. 
Razoumofskya laricis Piper, the most universally distributed and 
probably the most injurious of the entire genus, is associated with 
the western larch. This species in a single instance has been col- 
lected by the writer on lodgepole pine near Missoula, Mont. It is 
a significant fact that this infection is not vigorous and appears to 
be dying out. 2. americana (Nutt.) Kuntze is more strictly asso- 
ciated with the lodgepole pine, but is the cause of serious damage to 
the jack pine (Pinus banksiana) where these two species approach 
each other in Canada. fF. tsugensis Rosend., as far as observations 
in the field have gone, is confined to the hemlocks. 

The remaining species of importance may be divided into two main 
eroups, a fact that has not been heretofore set forth, viz, those associ- 
ated with the soft or white pines and those attacking the hard yellow 
pines. It seems that the members of one group are not in a single in- 
stance associated with the hosts of the opposite group. The former 
group includes the following species and hosts: Razoumofskya divari- 
cata (Engelm.) Coville on the nut or pifion pines, P. edulis and P. 
monophylla (6,p.253) ; R. eyanocarpa A. Nels. on P. flewilis (4, p. 146), 
P. albicaulis, and P. monticola. Pinus monticola has not been previ- 
ously reported as a host for these parasites. Pinus strobiformas, the 
Mexican white pine, is reported (11, p. 65) as the only host of 2. blu- 
meri (A. Nels.) Standley. The second group may be included by the 
two-form species: 2. campylopoda (Engelm.) Piper and &. erypto- 
poda (Engelm.) Coville. The former is principally injurious to Pinus 
ponderosa, but is common on P. attenuata (7, p. 366; 18) and P. 


jefireyt (10, p. 38). The latter is likewise an injurious parasite on — 


1A bies concolor is also host for Phoradendron bolleanum (Seem.) Hichl. (5, p. 193). 


| 


Oe 


ee es vr 


, 
| 
: 
. 
i 
, 


MISTLETOE INJURY TO CONIFERS. 33 


P. ponderosa, but occurs on P. jeffreyt (5, p. 192), P. arizonica (2, 
p. 243), and P. mayriana (2, p. 243). BR. campylopoda has recently 
been collected by the writer near Coeur d’Alene, Idaho, on P. contorta. 
Sparingly distributed throughout the Northwest are some large forms 
of Razoumofskya on Abies. Plants collected by the writer on Abies 
grandis and A. concolor are apparently the same as that described by 
Engelmann (3, v. 2, p. 106) on the former host under the name 
Arceuthobium occidentale var. abietinum. Although it would prob- 
ably be better on morphological grounds to refer this form to 
R. campylopoda (Engelm.) Piper, as Engelmann’s Arceuthobium 
occidentale is now named, owing to its seeming close affinity to 
the genus Abies and the absence of cross-inoculation data it could 
well be raised to specific rank. These mistletoes in point of mor- 
phology are in great contrast with the small forms on Abies previ- 
ously mentioned. They may be considered typical of a group of 


large forms occurring only on Abies. 


From the foregoing, it seems possible that the members of the genus 
Razoumofskya may be arranged in a series of natural groups accord- 
ing to their host relationships. It is also interesting to note that the 
largest, the longest lived (both cortical and aerial parts), and the 
most strictly parasitic forms are associated with the hard or yellow 
pines. These pines exhibit anatomically a high differentiation. This 
may throw some light on the nutrient relation of some mistletoes 
to their hosts; also their family peculiarities. 


SUGGESTIONS FOR CONTROL. 


It is clear from the foregoing pages that the damage to forest 
erowth by the mistletoes of coniferous trees in the Northwest is of 
sufficient importance to receive the attention of every forester. Steps 
should be taken in all logging operations, where local problems of 
economy do not interfere, to make a beginning of the eradication of 
mistletoe by marking every infected tree for cutting. In some cases it 
would seem advisable to introduce into the contract a special clause 
dealing wholly with mistletoe-infected trees. The most injurious of 
the mistletoes of the genus Razoumofskya on coniferous trees, as indi- 
cated, are in the main confined to their own particular hosts or to spe- 


cial groups; hence, it is not advisable to establish in mistletoe regions 


pure stands of a species much subject to attack. In this respect the 
problem of the control of mistletoe is similar to that of forest-tree 
fungi. Mistletoes being light-loving plants, close stands should be 
maintained as much as possible on all exposed parts of the forest. 
For the same reason rims of canyons and all exposed areas, such as 
the borders of bench lands, natural parks, shores of lakes, etc., should 


_ be protected with species which are not usually subject to the ravages 


34 BULLETIN 360, U. S. DEPARTMENT OF AGRICULTURE. 


of mistletoes (Pl. IV, fig.2). In this class would fall the firs, spruces, 
arbor vites, cedars, junipers, and yews. If this can not be done, 
owing to certain requirements by these species on soil and climate, the 
stand should be composed of as many different species as possible. 
Aside from reasons already set forth, isolated seed trees heavily 
or even slightly infected by mistletoe should not be retained. The 
vigor of the parasite on the parent tree will become greater, owing 
to its response to open and well-lighted conditions. Reproduction 
under the tree and in its near vicinity, if of the same species, will 
readily become infected. The same will be true of seed plats. The 
force developed within the mature seed capsule of these mistletoes 
and exerted in the expulsion of the seed is a factor of great signifi- 
cance for the spread of the parasite. It has been demonstrated in 
the case of one species that this force is sufficient, starting at an 
elevation of 8 feet on the level, to carry the seed a distance of over 
66 feet. In addition to the forcible expulsion of its seeds by the 
parasite, strong wind is an important factor in seed dissemination. 
In one instance seeds of the larch mistletoe were collected in number 
from the roof of a cabin one-fourth of a mile away from the nearest 
infected tree. This is not at all extraordinary, in view of the fact 
that the larches of the region are very tall and are heavily infected 
in the crown. Also strong winds are frequent during the period of 
seed maturity. Birds and animals play a minor role in the distri- 
bution of the seeds of these mistletoes.1_ In the present instance, 
however, the seeds adhered to the substratum in the usual and nor- 


mal manner and could not have been transported in such numbers — 


by any other means than strong wind. 

In view of the fact that strong air currents are factors in the dis- 
semination of the seeds, some consideration should be given to the 
topography and prevailing winds of a region where mistletoe 
abounds, as influencing the selection of seed plats (if such methods 
are employed), the placing of strip cuttings, and even of nursery 
and transplant beds. On a previous page, the tender age at which 
coniferous seedlings are liable to infection by mistletoe is indicated, 
so that the above statement regarding nursery sites is not merely a 
conjecture. Since considerable time elapses between the actual 
penetration of the primary sinker and the time the infection becomes 
conspicuous, three years in some instances, it is quite possible for 

1In Bulletin 317 of the U. S. Department of Agriculture, page 24, the writer pub- 
lished a footnote on the role of birds and animals in the distribution of the seeds of these 
mistletoes. Since this publication was issued additional observations show that the seeds 
are probably more widely distributed by this means than was formerly believed. A rumor 
has been long extant that grouse feed upon the mistletoes. This has recently been verified 
by the writer by finding in the crop of a grouse the mature seeds and plants of the 
Dougias fir and larch mistletoes. Mr. Donald Morrison, an old, experienced hunter resid- 
ing in the mountains near Missoula, states that grouse in the late fall, with the coming 
of the winter snows, make a practice of congregating in the dense houselike brooms of 


the Douglas fir mistletoe. Mr. Morrison states quite positively that these birds feed upon 
the plants and mature seeds of these parasites when other forms of food become scarce. 


aiensgel the deiaen . ae 


ee ee ee 


MISTLETOE INJURY TO CONIFERS. 35 


young infections on nursery stock to escape detection. Accordingly, 
young infected seedlings may become a means of distributing and 
establishing the parasite in plantations generally, not only locally 
but to far distant regions, when growing stock is shipped either for 
experimental purposes or for permanent plantings. That this is 
possible is shown by the discovery in the planting areas near Wal- 
lace, Idaho (Coeur d’Alene National Forest), of a yellow-pine 
seedling showing a very recent infection of mistletoe. Since the 
plantings were made on a widely denuded area and no yellow-pine 
mistletoe is as vet known to occur in the immediate region, 1t seems 
that the seedling must have become infected while at the home 
nursery at Boulder, Mont., where this mistletoe occurs. In view of 
the fact that there is a very grave danger of transporting agents 
injurious to forest growth, either fungous diseases or mistletoe, by 
sending nursery stock to distant parts of the country, the need of 
strict sanitation in the neighborhood of forest-tree nurseries can not 
be overemphasized. Whenever new nursery sites are planned in or 
near forests, a close pathological survey should be made of the 
surroundings, and trees diseased or suppressed from any cause what- 
ever should be cut out. This should be done also where nurseries 
are already established. 

The influence of the physical type on the severity of attack should 
receive considerable attention in any plan of management of forests 
in mistletoe regions. Forest Assistant Gilkey, in a report on the 
western larch of the Whitman National Forest, states that “a total 
of several hundred trees in various parts of the forest shows 79 per 
cent of the larch to be attacked on the dry-slope type, with only 27 
per cent on the more moist sites.” The writer’s own investigation in 
the same forest shows an even greater difference between the moist- 
valley type and the more exposed slopes, which was 87 per cent for 


the latter and 15 per cent for the former. The severity of the infec- 


tion on yellow pine and Douglas fir in other regions likewise shows 
wide extremes as influenced by elevation and exposure. Mr. E. E. 
Hubert, of the Laboratory of Forest Pathology, reports from ex- 
tensive observations during a reconnoissance of the lodgepole pine 
in the Big Hole Valley, Mont., that the most favorable sites for 
mistletoe are exposed dry ridges and south slopes, where the infec- 
tion ranges from 50 to 70 per cent of the stand. In the valley type 
the percentage of infection was much lower. 

In view of the fact that all economic species so far observed are 


- subject to attack at any age, it is hardly possible to establish an age 


at which infection becomes so serious as to interfere with the mer- 
chantability of the host. In regions of heavy mistletoe infection it 
would be quite impossible, for the reason that there is a much greater 
chance for all age classes to become infected. In numerous in- 


36 BULLETIN 360, U. S. DEPARTMENT OF AGRICULTURE. 


stances, however, it is noted that in some regions Douglas fir, larch, 


and lodgepole pine first become conspicuously infected at sapling or 


pole size; that is, it has required several years for earlier infections 


to become prominent. In any case, the matter turns on the time of — 


life at which a tree becomes infected. If seriously infected before 
pole size is reached, the whole tree will in all probability be a cull 
and a menace to the forest. If infected during or after pole age, the 
tree may furnish some merchantable material, but will mature far in 
advance of uninfected trees of the region. Trees infected during 
early maturity may not be seriously influenced by the parasite ex- 
cept that their life functions may be slightly changed by brooming 
and breakage of branches, thus hastening the period of decline. 
Cutting old and suppressed mistletoe trees is, of course, a saving in 
several ways, not only to the future forest, but it is getting the best 
out of a rapidly declining forest capital. Their destruction, how- 
ever, does not mean that a great advance is being made in eradicating 
the mistletoe from the region. It simply lessens the chance of infec- 


tion for a time. Cutting the old and merchantable infected trees and — 


leaving the younger unmerchantable but infected growth will not 
answer the purpose of control in regions of heavy infection. Very 
frequently the removal of only the more merchantable mistletoe 


———— ee ee 


trees causes the parasite on the trees that are left to develop more © 


vigorously. Numerous observations show that infected trees of 
various ages succumb very rapidly to-the parasite after a certain 
percentage of the stand has been cut out. For this reason marking 
the most seriously infected trees for cutting, with the prospect of 
the least infected reaching a normal maturity or a state of high mer- 


chantability, should in many regions be discontinued. The only — 


plan left, then, in many regional units of infection is to practice 


heavier marking than hitherto employed, or, better still, clean cut- — 
ting. It is believed that a close survey of the forests of each district ~ 


will result in the discovery that there are units or centers of great 
infection either for one species of mistletoe or for different species. — 
Instances of great regional infection for the Northwest have al- 
ready been indicated. Strange to say, in some cases these centers 
of infection are quite sharply defined. It seems entirely possible 
that if these regions were carefully studied and mapped as to the 
possible environmental factors governing the vertical and horizontal 
distribution of the parasite, much practical knowledge would re- 
sult. If the region should be accessible, the sales policy could be 
modified, with strong emphasis on the control of the mistletoe, and 
the knowledge already gained from a detailed study of the region 
should be available for future forest management. It must be re- 


membered that the great injury now exhibited by forest growth is — 
the accumulation of many years of unhindered activity by these — 


MISTLETOE INJURY TO CONIFERS. 87 


mistletoes. Through a proper appreciation of the need of adopting 
control measures in all sales areas where the percentage of infection 
is high and in all replanting projects in mistletoe regions, with the 
free-use privileges of mistletoed trees and the cutting of all infected 
growth in the vicinity of forest-improvement stations, a good be- 
ginning could be made toward the eradication or the lessening of 
the ravages of these parasites. 


SUMMARY. 


The conifers in the Northwest most subject to injury by mistle- 
toes of the genus Razoumofskya are Larix occidentalis, Pinus con- 
torta, Pseudotsuga taxifolia, and Pinus ponderosa. In the order 
of the above-named hosts the mistletoes most responsible for the 
greatest damage are Razoumofskya laricis, R. americana, Rh. doug- 
lasit, and 2. campylopoda. 

The general nature of the injury by these mistletoes is expressed 
in a gradual reduction of the leaf surface of the host, which causes 
a great reduction of growth in height and diameter. 

New infections take place only through the agency of a germinat- 
ing seed, which reaches the point of infection through the natural 
expelling force of the seed capsule, which may be made more effec- 
tive in point of distance traveled by the aid of strong winds, by 
falling from branches above after they have been loosened from — 
their original resting place by rains, and by animal life. 

Trees of all age classes are liable to infection provided the mistle- 
toe seeds fall on parts of the host not yet protected by the mature 
cortex. The parasite may spread from the original point of infec- 
tion into older cortical tissues, which are not liable to infection 
from without. The spread of the cortical stroma in the reverse 
direction from the line of growth of the branch may continue until 
the outer cortex becomes too thick for the aerial shoots to penetrate 
it. After this, the cortical roots become suppressed and eventually 
die, or they may become wholly parasitic. 

Excessive mistletoe infection of the lower branches of a tree may 
cause the upper portion of the crown to die, giving rise to the phe- 
nomenon commonly called staghead or spiketop. Severe infection 
throughout the entire crown often results in the death of the tree. 
Young seedlings from 3 to 6 years old are often killed within a com- 
paratively short time after infection. 

Infection on the branches in practically all cases causes the forma- 
tion of large brooms, which seriously interfere with the life function 
of the tree. The same is true in the case of infection on the trunk, 

whereby burls are formed. 

_ The weakening effect of the formation of burls and brooms by 
mistletoe on forest trees is often responsible for serious depredations 
by fungi and forest-tree insects. | 


38 BULLETIN 360, U. S. DEPARTMENT OF AGRICULTURE. 


In point of quality and quantity the seed-producing capacity of 
trees suppressed by mistletoe is far below that of normal uninfected 
trees. 

Mistletoe can be controlled. It is suggested that a beginning may 
be made in its eradication or in the reduction of the ravages caused 
by these parasites by working along the lines indicated in the last 
section of this bulletin. 


(1) 
(2) 
(3) 
(4) 
(5) 
(6) 


(7) 
(8) 


(9) 


(10) 
(11) 


— (2) 


(13) 


LITERATURE CITED. 


ALLEN, HE. T. 
1902. Western hemlock. U.S. Dept. Agr., Bur. Forestry Bull. 33, 55 p., 
ie...’ 13) pl. 


BLUMER, J. C. 
1910. Mistletoe in the Southwest. Jn Plant World, v. 18, no. 10, p. 
240-246. 
Brewer, W. H., and Watson, SERENO. 
1876-1880. Botany. [Geological Survey of. California.] 2 v. Cam- 
; bridge, Mass. 
CouLtTeEr, J. M. 
[1909.] New Manual of Botany of the Central Rocky Mountains 
646 p. New York. 
CovILLE, F. V. 
1893. Botany of the Death Valley expedition . . . Jn Contrib. U. S. 
Nat. Herb., va 4, 368 p., 21 pl., 1 map. 
ENGELMANN, GEORGE. 
1887. Loranthacez. Jn Report upon United States Geographical Surveys 
West of the One-Hundredth Meridian, v. 6, Botany, p. 251-254. 
JEPSON, W. L. 
1901. A Flora of Western Middle California. 625 p. Berkeley, Cal. 
MacDovuaeat, D. T. 
1899. Seed dissemination and distribution of Razoumofskya robusta 
(Engelm.) Kuntze. Jn Minn. Bot. Studies, s. 2, pt. 2, p. 169-178, 
1 fig., pl. 15-16. 
MEINECKE, E. P. 
1912. Parasitism of Phoradendron juniperinum libocedri Engelm. Jn 
Proc. Soc. Amer. Foresters, v. 7, no. 1, p. 35-41, pl. 1-e. 
1914. Forest tree diseases common in California and Nevada. 67 p., 
24 pl. Washington, D. C. Published by the U. S. Dept. Agr., 
Forest Service. 
NELSON, AVEN. 
1918. Contributions from the Rocky Mountain Herbarium. XIII. Jn 
Bot. Gaz., v. 56, no. 1, p. 63-71. 
PEARSON, G. A. 
1912. The influence of age and condition of the tree upon seed produc- 
tion in western yellow pine. U.S: Dept. Agr., Forest Serv. Cir. 
196, 11 p. 
PIERCE, G. J. 
1905. The dissemination and germination of Arceuthobium occidentale 
Eng. In Ann. Bot., v. 19, no. 73, p. 99-113, pl. 3-4. 


39 
O 


ADDITIONAL COPIES sis its 
OF THIS PUBLICATION MAY BE PROCURED FROM — 
THE SUPERINTENDENT OF DOCUMENTS 
GOVERNMENT PRINTING OFFICE ss 
" WASHINGTON, D. c. +4? es 

AT T 
15 CENTS PER COPY reat: © 


' ST? nae 


i rrr? ’ 
75 i t 
, 
if xX sf : | 
~ [434 
Thon 
eq? |. ery 
‘a 
t 
erae: 42 
rivals 7 
“; 4 
fay rit 
¢ ti biti aS 


UNITED STATES DEPARTMENT OF AGRICULTURE 


Contribution from the Bureau of Plant Industry 
WM. A. TAYLOR, Chief 


Washington, D. C. PROFESSIONAL PAPER. April 7, 1916 


FOREST PATHOLOGY IN FOREST REGULATION. 


By E. P. MEINECKE, 
Forest Pathologist, Office of Investigations in Forest Pathology. 


CONTENTS. 
Page. Page, 

Lhaiied $04.00) 4 ee ee ee ee ee 1 | Methods of investigation—Continued. 

Mepulation of yield sis... . 226. ee.eee eee. 2 Local pathology of white fir..........-..-. 35 
Ce a oe oe 2 Tabulation of data. 2... 6/2. <3 5525 s—2% 36 
TrOMathie s... i-c)-4---.-- fe 2. ae 6 Condensation of data......-. ee te A eg) wae 
ic! 230 0 Ee 8 Interpretation 22) . 205-42. Io. 3k. 46 
ly oe a 9 Conclusions and outlook. ..).....°\.9--'..--<: +5. 53 
Perma of transition... ..2...2---2-2-5-.- 15 Decay in relation to wounds.......-...-- 54 
Condition of timber stock...........-... 16 Forest regulation 0.0". £24. Js. 232 5k 54 
fo a a ee 16 Care of virgin forests.........-.---+: 54 
Eiierier species... 5.25... . 2222s is... 19 Forest regulation through timber 

Methods of investigation..........-.....-.-- 22 gales SUG si See eee ee | See 8 55 
Choice of species and site......-..-..-.-- 22 PON 2 ee Re Pp eee eS 57 
PelgmereteOds. (0.2. i Leese. 23 Pathological rotation and cutting 
Pathology of white fir................... 27 OyCles cL dts. gar. See ry Ls: 59 
PPenCrMIRNOMOCATPAS) 2... - Fos eenee seen 33 IOs een lH os ere eae. EI sai 3 62 

INTRODUCTION. 


At the time of the creation of the national forests in the United 
States the Government very suddenly found itself confronted with 
the problem of organizing an enormous acreage of practically virgin 
timber. It was natural that American forestry turned to the expe- 
rience of the Old World for guidance in this huge task; it was quite 
as natural that the present state of European forestry should have 
served as the ideal to be reached in the shortest time possible. In 
organizing the administrative machinery, European precedent could 
be followed more or less closely, but not so in almost all other phases 
of forestry. Except for certain economic factors and the develop- 
ment of modern machinery, conditions influencing the lumber 
industry in the United States are very dissimilar to those in the 
typical forest countries of central Europe. Our virgin forests them- 


Nore.—This bulletin discusses the bearing of modern forest pathology on forest regulation. 
98035°—Bull. 275—16——1 


2 BULLETIN 275, U. S. DEPARTMENT OF AGRICULTURE, 


selves, and consequently the timber for sale, are more or less in the _ 
condition of European forests of several hundred years ago. The 
administration found itself then in the position of a man forced to. 
take over not only an obsolete factory producing at random arti- 
cles of daily necessity in enormous quantities without having any 
control whatever over the quality turned out, but also a huge stock 
of products of all kinds and all values. Modern sales methods 
alone can not make the product any better, and the sudden adoption 
of modern methods of efficiency in the manufacturing end of the 
business would soon disorganize the entire factory. 

It is clear that in the most important branch of forestry, silvi- 
culture, the blind adoption of European methods must encounter 
serious difficulties. Perhaps we are too prone to look upon Euro- 
pean forestry as a science worked out in all its details, the results 
of which are universally accepted as definitely settled. Critical 
perusal of modern European forestry literature shows an entirely 
different state of affairs. Even in Germany many of the funda- 
mental problems of forest organization are steadily discussed and are 
far from being considered as settled. Furthermore, what Gaskill 1 
said 11 years ago is true to-day, namely, that ‘“‘European foresters 
have not developed a true system or science of silviculture capable — 
of being applied to virgin conditions or to all conditions.” 

The lessons taught us by earlier forest history in Europe, the 
adaptation rather than adoption of European principles to American 
conditions, and the development of new principles to suit our own 
special needs are therefore the means by which forestry in the United 
States will finally solve the silvicultural problems before it at the 
present day. 

REGULATION OF YIELD. 
WORKING PLANS. 


One fundamental problem has occupied the administration of the 
national forests ever since their creation, that of working plans as the 
expression of forest organization leading to sustained yield. 

_ Any speculation with regard to the adoption of a system of regula- 
tion must necessarily refer to the normal stand, whether this is clearly 
understood and stated or not. Now, there is no such thing as the 100 
per cent normal stand. Consciously or subconsciously the normal 
stand is taken as the ideal, and from this allowances are made accord- 
ing to the degree in which the stand deviates from the normal. It is 
a remarkable fact that even in European forestry no working system 
has developed of expressing with accuracy the value of allowances 
to be made. This is partly due to the fact that the managed Euro- — 
pean forests are relatively closer to the normal. Frequent thinnings ~ 
and improvement fellings eliminate most of the undesirable indi- — 


1 Gaskill, Alfred. Silviculture applied to virgin forest conditions. In Proc, Soc, Amer, Forest., vy. 1, a 
no, 2, pp. 62-69, 1905, (See p. 67.) 


FOREST PATHOLOGY IN FOREST REGULATION. 8 


- viduals from the stand, which is kept as fully stocked as possible. 
_ The problem is further simplified by the prevalence of pure stands or 
of stands composed of two, rarely more, well-matched species. The 
management of even-aged stands or stands of all ages also permits a 
_ relatively close approximation to the normal. 
_ All these factors are comparatively rare in our practically virgin for- 
_ ests, which are about as far from the normal as possible. As forests 
they are with few exceptions rather 100 per cent abnormal, and this 
applies equally well to all unmanaged practically and genuinely virgin 
forests of the world. The farther the forests are removed from the 
normal the less can European results from relatively normal stands 
_be applied, and particularly if the abnormality is complicated by the 
presence of a greater number of commercial species on the same 
stand, as is so often the case in our forests. Itis not to be expected 
that at the very beginning of its career the Forest Service should have 
possessed all the facts upon which to base a rational system of sus- 
tained yield. Intensive work of decades is necessary to secure even 
the very foundations. 

It is clear that this lack of fundamental facts must be reflected in 
any attempt to establish some system of sustained yield and, there- 
fore, in any policy of regulation of cut. While Kirkland + emphat- 

ically demands a policy of cutting national-forest timber on the 
Pacific coast on the basis of a sustained annual yield, Greeley,” on the 
other hand, points to the difficulties confronting the establishment 
of a sustained annual yield in the forests of the United States. In his 
‘opinion even, “modern conditions governing the distribution and 
sale of lumber make the sustained yield from the standpoint of a 
permanent supply for consumers of wood very much of a fiction.” 
We have at the present time no more authoritative statement con- 
cerning the policy of the administration of the national forests. 
With regard to the regulation of sustained yield, Chapman ° arrives 
at asimilar result in discussing the regulation of cut on national forests. 


Until recently the annual cut permitted upon national forests has been determined 
by Von Mantel’s method, based solely on the present nature of the merchantable 
stand and a somewhat arbitrary rotation. A few attempts have been made lately 
to base the cut upon the increment of the forest by use of the Austrian formula. At the 
‘same time there has come a general awakening to the fact that our knowledge of the 
actual increment of virgin forests is conspicuously lacking. Without this knowledge 
systematic regulation of yield must remain on crude and wholly unsatisfactory founda- 
tions. The question can not be dodged by quoting the generality that in virgin 
forests growth equals decay. 


+ 

1 Kirkland, B. P. The need of a vigorous policy of encouraging cutting on the national forests of the 
Pacific coast. Jn Forestry Quart., v. 9, no. 3, pp. 375-390, 1911. , 
_? Greeley, W.B. National forest sales on the Pacificcoast. In Proc. Soc. Amer. Forest., v. 7, no. 1, 
pp. 42-50, 1912. 
%Chapman,H.H. Coordination of growth studies, reconnaissance and regulation of yield on national 
forests. In Proc. Soc. Amer. Forest., v. 8, no. 3, pp. 317-326, 1913. 


4 BULLETIN 275, U. S. DEPARTMENT OF AGRICULTURE. 


This ‘‘ generality,’ in which almost every word is open to criticism, 
seems to have become one of the stand-bys of American forestry. It 
finds its chief support in the assumption that our forests to-day, © 
having been untouched by man and exposed to the same factors of | 
their surroundings since times immemorial, must represent more or 
less exactly the same character they had 100 or 1,000 years ago. But 
we have practically no genuinely virgin forests; in the great majority 
of commercial accessible stands—and here we are interested only in — 
these—man has for centuries practiced some kind of primitive for- — 
estry by setting fires. This “Piute forestry” has changed the aspect | 
of many stands so completely that the term ‘virgin forests” is far — 
from being correctly applied. At best, can one speak of scattered | 
yirgin stands here and there. Even in the latter the assumption that — 
the present stand has more or less the same character as 100 to 1,000 
years ago reposes upon another assumption, namely, that here the — 
ecological formation has reached the final stage of development and | 
has come to stay. Of the remaining part of the cited rule of thumb | 
all factors are more or less unknown. | 

Our knowledge of increment is, according to Chapman, “con- | 
spicuously lacking.” + We know at as little about actual une t 
and progress of decay in virgin forests, so that the “generality” / 
reduced to an equation in which all factors are unknown. Bailes 
the term ‘decay’ leaves out all losses from the decrease in funibee 
of trees steadily going on in the forest, as in every community of | 
living beings. Prompted, perhaps, by a subconscious realization of — 
this fact, the term “decay” in the equation is sometimes supplanted | 
by « deterioration.” This makes matters even worse. Deteriora- | 
tion in this connection often means the visible loss irrespective of | 
cause. It is primarily a numerical consideration. A number of | 
trees containing certain amounts of timber annually drop out through | 
various causes, and this loss is then said to offset the annual incre- | 
ment. Secondarily, it might include loss from decay. In forest | 
regulation it is not the number of trees and the volume of timber they | 
produce per acre that count, but the volume of sound, merchantable ¥ 
timber that we can expect to raise; and the only factor’i in the oeiinall 
tion of any value would be, eMevatpee! not decay only and deteriora- — 
tion or numerical loss of individual trees but “total loss.” The 
components of this total-loss factor are known. They include the 
dropping out of individual trees by death from suppression or “old | 
age,” fire, snowbreak, lightning, windfall, insects, diseases of vital 
parts of the tree, and finally loss through decay. What we do not~ 
know are the respective values to substitute for these components | 
in the actual figuring of total loss. | 


1More recently Barrington Moore has published a valuable study—Yield in uneven-aged stands—in ~ 
Proc. Soc. Amer. Forest., v. 9, no. 2, pp. 216-228, 1914. 


FOREST PATHOLOGY IN FOREST REGULATION. 5 


The same laxity noted in the use of the terms “decay” and “ de- 
terioration”’ is commonly found in the use of the term ‘ decadence,’’ 
as applied to a stand or a given species, which is often understood to 
include individual decadence from old age; that is, arrested or min- 
- imized growth, lability to attack from fungi and insects, and finally 
decay. The fact that a given species is unusually liable to heart rot 
does not make it decadent. Many of our most thrifty and aggres- 
sive species are particularly subject to heart rot. It is also doubtful 
whether this hypothetical knowledge, if ever attained, of the total 
rate of total loss in “virgin’”’ forests, as compared with the equally 
hypothetical rate of increment of the forests as a whole, would help 
us to any extent. The vastness of our forests in area creates a 
tendency either to think in broadest terms and to overlook the fact 
that a forest is an artificial unit made up of natural units, the stands 
with all their immense variety of character, or, on the other side, to 
take a familiar unit and to transfer its characteristics to the whole. 
The latter mistake is more easily remedied than the first. As a 
science, forestry must be founded upon inductive methods. Inten- 
sive study of detail alone can form a solid basis for the formulation 
of principles. 

_ What is needed is exact studies of all components of the total-loss 
factor per species before we attempt to fix the total-loss factor for 
the stand. 

Such detailed studies will be easiest in all-aged pure stands of a 
thrifty species little hable to decay. Unfortunately the vast majority 
of stands on national forests in the West are composed of two to 
five or more species of very different characters. It may be that the 
total annual loss equals the annual increment in some of the medium 
long-lived species of the pine group least liable to decay. It can 
not be true for the extraordinarily long-lived redwood and big tree, 
with their unusual resistance to decay, insects, and storms. It is 
equally untrue for all shorter lived species much exposed to decay 
and other influences that make for loss. Libocedrus decurrens, for 
example, although most aggressive and thrifty, is from an early age 
on liable in an uncommon degree to the attacks of Polyporus amarus, 
which renders as much as 70 or 80 per cent and even higher per- 
centages of the stand completely unmerchantable. Merchantable 
incense cedar is of high value; so much the greater, then, is the 
total-loss factor. The same is, mutatis mutandis, true for white fir 
and a number of other species. For all these the increment is not 
only offset but far exceeded by the decay of the valuable heartwood; 
the total annual loss is far greater than the annual increment, 
although numerically the loss may not be apparent. 

_ The gain through increment, we must remember, consists of sap- 
wood of little value; the loss by decay, on the ker side, affects the 


6 BULLETIN 275, U. S. DEPARTMENT OF AGRICULTURE. 


valuable heartwood. Neither is there any constant accumulation of 
gain; after some years the sapwood is turned into heartwood and 
as such becomes liable to decay. In other words, in trees of this group _ 
infected with heartwood-destroying fungi, the value of newly formed ~ 
wood is small; when it becomes valuable by transformation into — 
heartwood it becomes subject to decay—that is, loss. This loss from 
decay is by its very nature as a heart rot confined to those individ- 
uals in which heart-rot formation has taken place. All trees below © 
the age of heartwood formation do not enter into consideration. In — 
speaking of a given stand the representation by ages must be of © 
prime importance. In all considerations of regulation it is neces- 
sary, therefore, to make a clear distinction between forests and — 
stands, between many-aged and even-aged stands, between mixed 
and pure stands, with particular emphasis on the composition of the 
stand as to species. All generalization is not only useless but mis- 
leading. | : 

But in full realization of the almost complete lack of fundamental — 
knowledge, American forestry is confronted with the urgent neces- 
sity of adopting, even temporarily, some kind of a system of regula- 
tion of yield. Whatever this system may be, its tentative, tempo- 
rary, and local character can not be overemphasized. 

Various attempts at adopting local temporary systems have found — 
an expression in the shape of working plans. Inseparable from the 
problem of working plans is the choice of a rational rotation and 


cutting cycle. 
ROTATION. 


The gleanings in American literature treating on the choice of 
rotation from a general point of view are rather meager, outside of a 
few well-known handbooks, such as those by Recknagel,! by Fernow,? — 
and by Roth,* particularly in so far as the practical application to — 
our virgin forests is concerned. Recknagel * excludes financial rota- 
tion from North American forests with the following words: k 

Since this method of calculating the rotation [financial rotation or that of highest 
soil rent] is suitable only to very intensive conditions, it would serve no useful pure 
pose to elaborate it at this point. 

On the other hand, the strong influence of European forestry is — 
clearly felt in the ever-recurring advice to adopt some kind of a ~ 
financial rotation in the national forests of the United States. Kirk- 
land ° is of the opinion that— 

1Recknagel, A.B. The Theory and Practice of Working Plans (Forest Organization), 235 pp. New j 
York, 1913. | 
2Fernow, B. E. Economics of Forestry, 520 pp. New York, 1902. 
3 Roth, Filibert. Forest Regulation, or the Preparation and Development of Forest Working Plans, | 
218 pp., illus. (maps). Ann Arbor, Mich., 1914. (His Michigan Manual of Forestry, v. 1.) 
4Recknagel, A. B. Op. cit., p. 39. 


6 Kirkland, B. P. Working plans for national forests of the Pacifie Northwest. In Proc. Soc. Amer. — 
Forest., v. 6, n0. 1, pp. 16-37, 1911. (See p. 21.) 


FOREST PATHOLOGY IN FOREST REGULATION. 7 


A rotation based on the financial rotation, possibly modified somewhat towards the 
rotation of the highest income, is no less adapted to Government forestry than to pri- 
vate forestry. 

Greenamyre ' advocates a financial rotation in the composite type 
of the Apache National Forest, the “rotation of greatest volume pro- 
duction being out of question.”’ In his specific recommendations 
for western yellow pine, Douglas fir, and blue spruce, however, rota- 
tion of greatest volume plays a far greater role than financial rota- 
tion. Such important factors in financial rotation as soil capital, 
quality increment, and rent are neglected or only hinted at. Value 
increment and depreciation enter. into his calculations in a general 
way only, evidently from a lack of exact figures. 

Barrington Moore’ expresses himself strongly against the adoption 
of a financial rotation. 

It would be out of place in this paper to enter into a discussion of 
the possibility at the present time of fixing a rotation of greatest 
income or a financial rotation more deeply than to point to the 
immense difficulties encountered as soon as we try to substitute actual 
values for the factors entering into their computation derived from 
experience in our own country. We lack at the present time the very 
fundamentals on which to base the determination of highest forest 
rent or highest soil rent. 

The Forest Service has, in full realization of the uncertainty of 
almost all factors which would or should enter into a financial rota- 
tion formula, adopted, for the present at least, a tentative silvicul- 
tural rotation of maximum-volume production. 

The factors entering into the determination of silvicultural rotation 
or of greatest volume being more easily accessible, it is quite natural 
that American forestry should show a tendency toward its applica- 
tion, as Shown in a number of published and unpublished working 
plans. 

Attempts at fixing some kind of a rotation age are found in several 
publications. Woolsey * tentatively proposes a rotation of 200 years 
for yellow pine without giving a basis for the choice of any particular 
system of rotation. 

Barrington Moore?‘ says that on the Plumas National Forest ‘‘the 
rotation should theoretically be that of maximum-volume produc- 
tion. The use of a financial rotation by the Government, in a region 


1 Greenamyre, H.H. The composite type on the Apache National Forest. U.S. Dept. Agr., Forest 
Serv. Bul. 125, 32 pp., 4 figs., 1913. (See p. 30.) 

2Moore, Barrington. The essentials in working plans for national forests. In Proc. Soc. Amer. Forest., 
v. 6, no. 2, pp. 117-128, 1911. (See p. 126.) 

8Woolsey,T.S. Western yellow pine in Arizona and New Mexico. U.S. Dept. Agr., Forest Serv. Bul. 
101, 64 pp., 11 figs., 4 pls., 1911. (See p. 51.) 

‘Moore, Barrington. Chapman’s method of studying yield, p. 93, 1913. To accompany forest plan, 
Plumas National Forest, district 5. Appendix (continued), Silviculture. (Unpublished. Furnished by 
_ courtesy of the U.S. Forest Service.) 


8 BULLETIN 275, U. S. DEPARTMENT OF AGRICULTURE, 


capable of producing large saw timber, can not be justified. * * * 
It would probably be better to fix the rotation at the period during 
which the rate of volume production is greatest or shortly after it, 
provided this is long enough to give the most valuable product.” 

Munger ‘ comes somewhat closer to a consideration of the financial 
factors for a rotation of Douglas fir in pure pA stands in the 
Pacific Northwest. 

From the quotations given, one fact stands out clearly: We are still 
groping more or less in the dark where choice of rotation is con- 
cerned, and we are even lacking the fundamentals upon which to 
base the principles to govern us in making a proper choice. It also 
appears that in many cases the term ‘‘actual felling age” should be 
substituted for rotation. Rotation in itself signifies return or succes- 
sion in a series. Fernow ” has warned, as early as 1905, against mix- 
ing up ‘‘actual felling age, the time when a stand is actually cut or to 
be cut, and normal felling age (rotation), the time when in g scheme 
of continued management it is proposed to have it cut again and 
again—a mere standard time. Few stands are cut in the age of the 
rotation determined for the forest as a whole.”’ Where a ‘‘rotation”’ 
of yellow pine, for instance, of 200 years is advocated, it is evident 
that this can not be meant to constitute the fixed period at which | 
yellow pine should be cut again and again in the future. It is really 
the actual felling age, the time when a given stand of yellow pine is 
actually to be cut in the future, not a succession of 200-year periods. 
The rotation itself will be much shorter, as European experience has 
shown us. Moreover, it is more than doubtful whether our successors 
in 200 to 400 years will pay much attention to the rules we may try to 
lay down for so remote a future. 


CUTTING CYCLE. 


The impossibility of predicting with even a modest degree of proba- 
bility what will happen in the future and of anticipating changes in 
conditions of an economic nature is responsible for the vagueness with 
which the question of fixing definite cutting cycles is treated. Tenta- 
tively, cutting cycles of about 50 years have repeatedly been advo- 
cated for uneven-aged stands (mixed and pure) under the selection 
method, as a policy to be followed on virgin national forests. If 
present economic conditions should prevail in the next 50 years—that 
is, if the demand for timber should continue to fall far short of the 
actual annual increment—it would hardly pay a lumbering concern 
of the future to extend its operations to cut-over areas before 50 to 
60 years had elapsed. Even then it seems doubtful whether the 

1Munger,T.T. The growth and management of Douglas fir in the Pacific northwest. U.S. Dept. Agr., 


Forest Serv. Circ. 175, 27 pp., 4 figs., 1911. 
2Fernow, B. E. Forest terminology. Jn Forestry Quart., v. 3, no. 3, pp. 255-268, 1905. (See p. 264.) 


FOREST PATHOLOGY IN FOREST REGULATION. 9 


amount of timber contained in the few overholders left as seed trees 

and in individuals at or just below the diameter limit established in a 

first cutting would prove attractive to purchasers of the future, pro- 

vided always no change in the lumber market should take place. 

The diameter limit now fixed on many national forests may be said 
_ to be about 12 inches, varying somewhat with the species and local 
conditions. Few trees below this diameter will reach such dimen- 
sions in 50 years as to form a merchantable stand, judged by our 
standards of to-day. 

If it is unwise blindly to take over principles and policies developed 
and more or less accepted in countries with old-established and far- 
advanced forestry and apply them to the first stages in the organiza- 
tion of our virgin forests, the study of the history of the forestry 
movement and development in other countries can not but be of the 
greatest practical value. We are justified also in assuming that the 
history of forestry will repeat itself and that forestry in all countries 
with large virgin or practically virgin forests in touch with the gen- 
eral market will run through the same phases of development as it 
did during the last centuries in central Europe, but at a very much 
faster pace, owing to the enormously enhanced facilities of transpor- 
tation and marketing and the rapidly increasing demand for timber. 

If this be true, a cutting cycle of about 50 years may prove too 
long. To judge from the development of timber values in Europe, 
our once cut-over stands should prove attractive in a shorter period. 

In determining the duration of cutting cycles, it is reasoned that 
the accessible virgin timber in the national forests should be cut once 
before operations return to the first areas logged over. How much 
time this first culling may consume we have no means of telling. It 
should be remembered, however, that the system naturally present- 
ing itself is that of selection cutting, and although there is a decided 
tendency toward heavier marking approaching clean cutting, this 
latter should be taken cum grano salis. Actually, the reproduction 
left includes all individuals up to and sometimes beyond 12 inches 
diameter breast high; that is, trees that have reached a considerable 
age and that in 50 years will have grown to what would be classed in 
European forestry as veterans. 


CUMULATIVE RISK. 


In fixing long-term cutting cycles, a most important point has not 
been sufficiently emphasized, namely, the “cumulative risk” from fire, 
windfall, frost, and so-called deterioration to which a given stand is 
exposed during so long a period. The longer the cycle the greater 
the ratio of risk. The unparalleled development of fire protection 
in the national forests of the United States, it is true, promises fairly to 
exclude actual destruction from fire on any large scale; but, as long as 


10 BULLETIN 275, U. S. DEPARTMENT OF AGRICULTURE. 


there will be fires from unpreventable sources (lightning), the risk in 
extended cutting cycles increases from year to year with the growth 
in value of the stand. The shorter the period in which a merchant- 
able stand can be produced and turned into cash the smaller will be 
the risk of loss. 

Loss from windfall is inevitable in many localities as a direct con- 
sequence of selection cutting. It is clear that the cumulative risk 
of a longer cycle is far in excess of a shorter one. Evidently, devas-_ 
tating windstorms are more likely to occur during a period of 50 
years than during a shorter one. Moreover, the loss in cash value, 
even in single trees, from windfall is bound to be heavier in the older — 
stands. The larger, bulkier, and therefore the more valuable the — 
tree, if sound, the more it is exposed to windfall. Falling trees in | 
brushing against their standing neighbors not infrequently cause — 
more or less serious wounds by bruising or tearing off the bark. 

The greatest risk, however, involved in the long cutting period is — 
from ‘‘deterioration,”’ so called. 

In nature a steady process of elimination goes on. Of thousands — 
of seedlings springing up together in dense growths, comparatively 
few reach sapling size, very few grow into poles, and fewer, even, to 
standards. This natural thinning through competition in the fight | 
for soil, food, and light is furthered by various dangers to which the — 
young plants are exposed, such as from certain insects, foliage and 
twig diseases, injury from mammals, snowbreak, frost, and drought. — 
Later, the surviving members of the stand are confronted with dangers 
from the same and other sources, such as suppression, lightning, in- 
sects, frost, and decay. The elimination of the weaker members — 
effects a selection of older, well-established individuals, some of which — 
may still suffer from the competition of their thriftier neighbors, but — 
are not forced out of the community, or, to use Fernow’s? well- — 
chosen terminology, trees which are “oppressed,” not suppressed. As 
long as improvement cutting on a larger scale on the national forests — 
is impossible, the percentage of oppressed trees will depend upon the 
length of the cutting cycle. Both these oppressed trees and their — 
more favored companions are exposed to dangers from which their © 
earlier life was free. ik 

Frost does a good deal of damage; here we are less interested in ~ 
the damage done to the foliage or to the bark than in those more or 
less long cracks in the wood which are caused by very low tempera- — 
tures. In cold weather the wood cylinder shrinks more in a tan- © 
gential than in a radial direction. Particularly at sudden low 
temperatures, when the volume of the outer layers decreases rather — 
suddenly while the inner layers are still free from frost and have 


>. = a _—_ 


1Fernow, B. E. Forest terminology. Jn Forestry Quart., v.3,n0. 3, pp. 255-268, 1905. (See p. 266.) 


FOREST PATHOLOGY IN FOREST REGULATION. 11 


shrunk but little, differences in internal tension will cause the outer 
layers to split vertically. With rising temperature the frost crack 
closes. Not always is the bark able to stretch sufficiently over a 
frost crack. Often the bark tears open, and if low temperature 
occurs again and again, the cracks will not be able to heal over and 
will remain open for many years, giving the air access to the heartwood 
and incidentally allowing spores of wood-destroying fungi to ger- 
minate and infect it. Even if no infection takes place, these frost 
cracks very seriously impair the value of the timber. The older and 
bulkier the tree the greater is the danger of frost-crack formation. 
The risk naturally increases with the length of the cutting cycle. 
Infection, of course, can take place only through open frost cracks; 
internal frost cracks, besides impairing the value of the timber, can 
not be without influence on the chemistry and physics of the wood. 
Although lightning occasionally strikes the smaller trees, even 


| poles and saplings, it is to be expected in the nature of things that 


taller trees will be more exposed to injury from this cause. Very 
little is known, so far, as to the actual damage done by lightning in 
our forests. Destruction of individual trees has been frequently 
reported, and Plummer' gives a series of illustrations of injury to forest 


_ trees from lightning. He treats, however, only of those very gross 
- cases in which even the least educated eye will recognize the cause 


of the injury. 

We know through Robert Hartig’s? classical investigations, which 
were continued by Von Tubeuf, that destructive lightning is rare 
in comparison to the overwhelmingly greater number of cases of 


_ lighter injury from lightning, varying from more or less large wounds 


visible on the outside of the tree to the small and insignificant local 
killing of parts of the cambium and of the living bark which can 
only be detected by ¢areful dissecting. 
The symptoms of lightning injury in our forest trees are easily 
recognized from Hartig’s excellent descriptions. They are particu- 
larly common and conspicuous in white fir. 

For practical purposes, we have to consider here only those forms 
of lightning injury which in some way endanger the life, the health, or 


the commercial value of the tree; this will include not only actually 


destructive cases, but also very large numbers of lesser injuries. 


The accumulation of risk during a long-time cutting cycle becomes 


self-evident, particularly in view of the fact that the danger from 
lightning increases quite out of proportion to the increase in height 


of the tree and the development of the root system. 


1Plummer, F.G. Lightning in relation to forest fires. U.S. Dept. Agr., Forest Serv. Bul. 111, 39 pp., 
16 figs., 1912. 

2Hartig, Robert. Untersuchungen itiber Blitzschlage in Waldbaumen. Jn Forstl. Naturw. Ztschr., 
Jahrg. 6, 1897, Heft 3, pp. 97-120; Heft 4, pp. 145-165; Heft 5, pp. 193-206. 83 figs. 

Hartig, Robert. Neue Beobachtungen iiber Blitzbeschidigung der Baume. Jn Centrbl. Gesam. 
Forstw., Jabrg. 25, 1899, Heft 8-9, pp. 360-081, figs. 47-71; Heft 12, pp. 523-544, figs. 81-110. 


12 BULLETIN 275, U. S. DEPARTMENT OF AGRICULTURE. 


Although young trees are also exposed to the attack of insects, it 
is clear that a colony of bark beetles will prove far more injurious © 
in killing a merchantable tree than in killing a small pole. Moreover, 
certain insects seem to have a predilection for larger sizes. The 
probabilities of attack increase with the length of the cutting cycle. 
Besides, the older the tree and the more it has been exposed to 
wounding the more liable does it become to attack by wood-boring 
insects which materially reduce the value of the timber. 

The timber contained in trees killed by lightning, as long as they 
are not destroyed, and in those killed by bark beetles may be utilized, 
and, with increasing timber values, will be utilized before they 
deteriorate. | 

The few veterans which have withstood the many dangers of earlier 
life do not go on living forever; they finally succumb like the rest. 

It is still an open question whether forest trees are theoretically im- 
mortal and die only through the devastating influence of severe 
storms, lightning, insects, certain diseases caused by fungi, such as 
Armillaria mellea and Fomes annosus, or because the root system of 
the veteran finally has exhausted all available resources of the soil 
within its reach. As we are interested here only in the future of eut- | 
over areas in relation to the length of the cutting cycle, it is unneces- — 
sary to enter into a discussion of this question. The cutting cycle for 
any one species will in all probability never be long enough to raise 
individual decadence from old age to the rank of an influencing factor. 
We should bear in mind, however, that individual decadence is not 
in itself deterioration unless decay sets in. 

The importance of the reduction in the timber value of the tree 
through the agency of fungi, on the other side, can not be overempha- 
sized. This reduction in timber affects either the prospective timber 
values—that is, the increment—or the present stock, or both. In the 
first case, the fungi in question (mostly Pyrenomycetes and rust fungi) 
inhabit living tissues of the foliage or of the young bark. The con- 
tinuous drain on the assimilates of the foliage either in the leaves 
proper or on their way down through the bark is evidenced by a 
decrease in increment of the tree, which in long cutting cycles will 
represent a very considerable loss in timber values. In other words, 
trees affected with foliage or bark diseases will be far from yielding the 
timber we might expect from sound trees. It must be mentioned 
that losses in prospective values are not alone due to fungi; mistle- 
toes and leaf-inhabiting insects are responsible for enormous deficits 
in yield. The economic role of the fungi, mistletoes, and leaf-inhab- 
iting insects in our virgin forests is highly important and will remain ~ 
so for a long time, on account of the difficulties connected with their — 
control and even more on account of our very limited knowledge con- 
cerning their life histories and specific action. More intensive studies 


FOREST PATHOLOGY IN FOREST REGULATION. 13 


on the members of this group must be left to the future. At the 
present time we are more interested in the preservation of our actual 
timber, including such values as will be formed in the near future. 

Actual timber values are seriously endangered by wood-destroying 
_ fungi, all of which belong to the Hymenomycetes. With the exception 
of a very few (Armillaria mellea, Fomes annosus), which in attacking 
living roots first cut down the increment of their host and then invade 
the wood of the bole, they all inhabit the heartwood and generally 
leave the sapwood intact. As the principal timber values are stored 
in the heartwood, the enormous damage they are able to cause is all 
- the more in evidence. All of these fungi are adapted to given hosts 
or groups of hosts; these groups are seldom very large. Polyporus 
amarus, for example, the cause of the extremely destructive heart 
rot of Libocedrus decurrens, can not grow, as far as is known, inany 
other host species. Trametes pim, on the other hand, attacks a 
number of pines, Douglas fir, and other conifers. The composition of 
the stand, as well as the representation of species, is therefore an im- 
portant factor in the ecology of these fungi. Only those fungous 
spores which land on trees of the species to which they are adapted 
have a chance after germination to enter into the tree. 

Being strictly heartwood inhabiting, these fungi, with the excep- 
tions mentioned above, can, of course, only attack trees which already 
have formed heartwood. But as they are unable to penetrate the 
bark, they are harmless unless their spores are carried on to some 
wound or opening (branch stubs) in the protective skin represented 
by the bark. The longer the host is exposed to wounding, the greater 
will be the chances for infection. 

As might be expected, therefore, the losses from decay in standing 
_ living trees are enormous in virgin forests. Even in the best managed 
forests of Germany losses from decay are heavy. Moller,! in figuring 
the damage done by Trametes pint in the pine forests of the Prussian 
Government, arrives at the astounding figure of more than 1 million 
marks (about $250,000) annual loss from this source alone. In the 
_ period from 1905 to 1908 the Prussian Government spent $87,480 in 
the control of Trametes pind in its pine forests.?. In 1914 this sum had 
increased to about $120,000.* 

In American literature no reliable figures are available relating to 
the annual loss from decay in standing timber in virgin forests. 
Such figures can be obtained only by exact studies on representative 
areas, the methods of which the writer has been trying to work out 

1MOller, A. Uber die Notwendigkeit und Méglichkeit wirksamer Bekimpfung des Kiefernbaum- 
schwammes Trametes pini (Thore) Fries. Jn Ztschr. Forst- u. Jagdw., Jahrg. 36, 1904, Heft 11, pp. 677- 
ae Der Kampf gegen den Kiefernbaumschwamm. In Ztschr. Forst-u. Jagdw., Jahrg. 42, 
1910, Heft 3, p. 133. 


_ 8MOller,A. Der Kampf gegen den Kiefern- und Fichtenbaumschwamm. Jn Ztschr. Forst- u. Jagdw., 
Jahrg. 46, 1914, Heft 4, pp. 193-208. 


14 BULLETIN 275, U. S. DEPARTMENT OF AGRICULTURE, 


during the last few years. In reason, all figures relating to loss in 
timber from decay, insects, lightning, etc., should apply only to such 
forested areas as are accessible at present or which will be in all 
probability accessible in the not too remote future. Inaccessible 
stands, whatever their protective value, do not represent timber 


values, and it is obviously wrong to include them in any estimate — 


of the damage done to our timber stock on hand. 

The rate of progress of decay in the individual tree is altogether 
unknown beyond vague guesses. 

Hartig ' has tried to figure the rate of growth of the mycelium, for 
instance, of Homes igniarius. Moller? has made an attempt to figure 
the rate of growth of Trametes pvm and resulting decay in Pinus 
silvestris from actual measurements in artificially infected trees. It 
is clear that unless such experiments are carried over a great many 


years, only the rate of growth of juvenile fungus plants starting from — 


the infection can be measured, which can not be taken directly as a 
guide for figuring the growth of the older or mature fungus plants. 
Besides, the experiment is based upon the assumption that the 
fungus, after once having gained access to the interior of the tree, is 
independent of possible individual differences of its substratum, or, 
in other words, that the rate of growth is a fixed factor, irrespective 
of individual properties of the heartwood. This assumption has no 
solid basis. The rate of growth of the fungus plant, and therewith 
of decay, is undoubtedly one of the most inaccessible chapters of 
forest pathology, on account of the difficulty in finding a stable point 
of issue. There is at present no reliable method known of deter- 
mining the actual extent of decay in the standing living tree. In- 
direct methods are the only means presenting themselves to-day; 
they leave much to be desired with regard to accuracy and can not 
be expected to yield results unless carried on over a long period. 
What we do know is that decay in standing living timber from 


heartwood-destroying fungi causes very heavy losses and that decay — 


is progressive. Sporophores develop on decaying trees, and the dis- — 
ease spreads through spores from one tree to other individuals of the — 


same and sometimes of other species. Moreover, the decay starting 


from an incipient infection progresses in the heartwood of the in-— 
dividual tree until its most valuable lumber is destroyed. Decay — 


being progressive, the cumulative risk from this source in long 
cutting cycles is therefore far greater than in the case of lightning or 
other injurious agents. 


Unlike insects, heartwood-destroying fungi have few or no natural | 


enemies; there is no such thing as ‘‘biological control”’ of decay. , 


1 Hartig, Robert. Die Zersetzungserscheinungen des Holzes der Nadelholzbiume and der Hiche ... p. 116. 


Berlin, 1878. 


2Moller, A. Der Kampf gegen den Kiefernbaumschwamm, In Ztschr. Forst- u. Jagdw., Jahrg. 42, — 


1910, Heft 3, pp. 129-146, (See p. 145.) 


- FOREST PATHOLOGY IN FOREST REGULATION, 15 


PERIOD OF TRANSITION. 


American forestry stands now at the very beginning of a period of 
transition from the handling of virgin forests to actual forest regula- 
tion. The most urgent problem, therefore, consists in how to take 
care of our forests as we have them, with all their defects, with in- 
dividual decadence and decay, and to leave them to future genera- 
tions in as favorable a state as possible, judged by our very limited 
insight of to-day. At the present time the only means at the disposal 
of the Government to carry out any plans in forest regulation based 
upon what appears to us as sound silviculture is through timber sales. 
The Government does not and can not cut its own timber. It is 
therefore entirely dependent upon a highly variable outside factor 
with regard to the most important part of its silvicultural work, a 
factor over which it has but little control. All attempts at the regu- 
lation of yield must then be concentrated on timber-sales areas. A 
comparison between the area actually cut over annually and the 
total national-forest area that may eventually become accessible to 
logging operations will show the severe hardship under which the 
Government is forced to work. Moreover, timber sales do not 
always occur where they are most needed from a silvicultural point 
of view, nor do they always cover the entire natural units upon 
which it is desirable to prepare for a system of regulation. A com- 
prehensive system of regulation on a larger scale following natural 
units is out of the question as long as the Government is not in a 
position to do silvicultural work on its own land where it is most 
needed. 
The aim of the Forest Service at the present time consists less in 
how to do the greatest amount of good to future generations than in 
how to do the least harm and at the same time to do justice to our 
present-day conditions. Instead of exhausting our energies in sterile 
speculation of what might happen in 100 to 200 years from now, there 
is a strong tendency toward applying them first to the analysis of the 
most urgent needs of to-day and then to the exact and painstaking 
study of all the innumerable factors which enter into a comprehensive 
plan for the future structure of American forestry. It is well to 
remember that so far, not even the methods leading to the majority 
of such studies are worked out. The necessity of taking care of our 
present-day timber supply and of providing for the future in an exten- 
sive rather than intensive way has found strong expression in Chap- 
man’s‘ “American Method,” where regulation is based not only on 
present volume and annual growth, but also on the ‘actual condition 
and amount of timber in the different age classes, with approximate 
knowledge of the behavior and condition of the age classes for an 


oe, H.H. Coordination of growth studies, reconnaissance and regulation of yield on national 
orests. Jn Proc, Soc, Amer, waneaty, v. 8, no, 3, 1913. pp. 317-326, (See p. 323.) 


16 BULLETIN 275, U. S. DEPARTMENT OF AGRICULTURE, 


extensive future period.” If “condition” is defined as state of health, | 
not only as far as thriftiness of growth is concerned, but also with | 
special regard to degree of merchantability as influenced by decay, | 
the condition factor becomes a subject of pathological study. 

Condition of the timber we hope to raise for the future, in the | 
definition as given above, has a strong bearing on the possible 
regulation of yield. There can be no sense in figuring cutting? 
cycles or rotation for future generations to follow unless we assume © 
that our successors will find the area we have cut over covered © 
with a stand not only apparently but really merchantable; in other © 
words, with timber that is not rendered valueless by decay. The | 
most ingenious speculation as to future yield is without any value — 
whatever unless we have some way of figuring how long the steadily | 
increasing but admittedly perishable timber stock can be left in the | 
forest before it is liable to destruction by fungi. | 

The most important problem before us, therefore, is the determi- 
nation in definite values of the condition of timber stock, present and — 


future. 
CONDITION OF TIMBER STOCK. 


The condition of the timber as a factor in regulation may be — 
expressed as the relation of the volume of timber destroyed or rendered © 
unmerchantable by injurious agencies to the ideal volume of merchant- © 
able timber; or, in so far as forest regulation is interested not merely | 
in the present but in the future, as the relation of the mean annual © 
total loss to the mean annual increment. | 

It has already been pointed out that the concept of the relation of | 
the mean annual total loss to the mean annual increment is without 
any value whatsoever as long as both factors are unknown. We are © 
beginning to know in a small way something about the mean annual — 
increment of certain species in certain types of some of the national — 
forests. We are still completely ignorant as to the influence that the — 
only silvicultural act of any importance open to the Forest Service, | 
that is, cutting on timber-sales areas, will have on the increment of — 
the remaining trees. This knowledge will come in due time. The | 
value of the total-loss factor is altogether unknown. In order to | 
attack this problem it is necessary to analyze it, to reduce it to its — 
several components, and to study each in its turn. By synthesis the 
total loss can then be computed and the true relation to increment | 


determined. 
TOTAL LOSS. : 
The analysis of total loss already given shows that its components 
are known, but not their values. Of all these components the most 
important, the one that has the strongest bearing on the value of the 
stock of timber at hand, is loss from decay or heart rot caused by a 


group of heartwood-destroying fungi. Very young trees are not 


FOREST PATHOLOGY IN FOREST REGULATION. ay 


a 


susceptible to heart rot. No heart rot is possible before heartwood 
is formed. Unfortunately, we do not know anything about the 
formation of heartwood in our American species with relation to the 
age of the tree. The younger trees, while at present immune, will, 
in growing up and after formation of heartwood, become just as subject 
to heart rot as are their older companions. It is, then, of prime 
importance to know at what age living trees of a given species become 
particularly liable to attack from the one or more heartwood-destroy- 
_ ing fungi that use their heartwood as a source of food. It 1s, further, 
of the utmost importance to know whether there are any conditions 
in the tree or outside of it that exert an influence over the develop- 
| ment of the fungi once they have gained access to the heartwood 
_ of a tree to which they are adapted. 
_ Beyond general statements to the effect that overmature trees do 
_ deteriorate from heart rots, very little information is to be gathered 
from American literature concerning the average age at which certain 
tree species become liable to attack from heartwood-destroying fung1. 
Greenamyre‘! mentions that in the Apache National Forest the 
decay in Douglas fir ‘‘no doubt largely offsets the growth’’ after the 
age of 210 years is reached. 
Munger ? gives a little more specific information: 
The amount of decay found in living Douglas firs up to the time they are 150 years 
_ old or so is very small, but in mature and overripe timber there is a great deal of 
defect due to decay. . . . Douglas fir trees resist infection from fungi well until 
_ they become mature, when, because of the opening up of a stand, breakage, and scars 


due to the action of the elements and of fire and insects, and also because with ad vanc- 
_ ing age their resistant power becomes less, they offer entrance to fungi. 


It is not clear from the context whether Munger’s figures are an 
estimate or are based on actual methodic investigation and measure- 
ments. 
Findley Burns,* in speaking of conditions on the Crater National 
Forest, gives the following information: 
Many of the older Douglas firs are affected by adry rot. . . . White fir is especially 


susceptible to decay, and many trees above 40 inches in diameter on the forest are so 
rotten as to be valueless, even for cordwood. 


In the latter case, age is supplanted by diameter, which answers 
perfectly well if diameter invariably corresponds to age. 

_ Barrington Moore and R. L. Rogers‘ incidentally give some 
interesting notes on the age of infection of balsam fir, which on the 


1Greenamyre, H. H. The composite type on the Apache National Forest. U.S. Dept. Agr., Forest 

‘Serv. Bul. 125, 32 pp., 4 figs., 1913. (See p. 31.) 

_ 2Munger,T.T. The growth and management of Douglas fir in the Pacific Northwest. U.S. Dept. Agr., 

Forest Serv. Circ. 175, 27 pp., 4 figs., 1911. (See p. 10.) 

_ Burns, Findley. The Crater National Forest. U.S. Dept. Agr., Forest Serv. Bul. 100, 20 pp., 4 pls., 
1911. (See p. 12.) 

_ 4Moore, Barrington, and Rogers, R. L. Notes onbalsam fir. Jn Forestry Quart., v. 5, no. 1, pp. 41-50, 
1907. 


98035°—Bull. 275—16 2 


18 BULLETIN 275, U. S. DEPARTMENT OF AGRICULTURE. 


area investigated was 50 years in pure stands and 85 years when 
mixed with hardwoods. They speak of butt-rot only, without 
specifying the cause; unfortunately, the numerical basis from which 
their figures are derived and their methods are not given. 


The bearing on management of the age at which decay becomes a 


seriously damaging factor is very rarely realized. 

Clapp,’ in speaking of incense cedar and white fir, clearly recognizes 
that where these ‘‘inferior”’ species are also defective, ‘‘an attempt 
should be made, at least in selection stands, to reduce their rotation 
to one which will produce sound timber.” 

In a recent article, D. T. Mason ? advocates a rotation of 100 years 
for western white pine, on the ground that this species on the average 
gives a maximum yield at this age and that from about the same age 
fungi, and particularly insects, generally succeed in doing a large 
amount of damage. 

It would serve no purpose to continue quoting the few and scat- 
tered notes on the relation of age to decay, of a similar indefinite 
nature found in American literature. By way of consolation, it may 
be said that foreign literature does not abound very much more than 
our own in definite information regarding this point. Although 
the importance of the age at which forest trees are most liable to 
attack from heartwood-destroying fungi is frequently hinted at in 
German literature, Martin * is the only German forester who, to the 
knowledge of the writer, has given more than a cursory discussion 
of the relation of this age to rotation. In speaking of the immense 
damage done in Prussian pine forests by Trametes pum, he attempts to 


show from somewhat meager material how the increase in loss from 


this cause should lower the rotation. 

All computations of the amount of decay in German forests must 
necessarily be incomplete, since from an early age all undesirable 
individuals, including, as a matter of course, all trees with visible 
signs of decay, are eliminated in improvement cuttings. The result 
is a stand of a comparatively high degree of soundness. Even in 
such stands Martin finds (p. 688) that in a given district the per- 
centage of decay in wood good for fuel only in the 100-year class was 
11, in the 120-year class 22, in the 130-year class 31, in the 140-year 
class 37, and in the 160-year class 42. He points out that in unsound 
stands the felling age must be lowered in order to secure the maximum 
income. Martin‘ again discussed similar ideas in 1910. 

1Clapp, E. H. Silvicultural systems for western yellow pine. Jn Proc. Soc. Amer. Forest., v. 7, no. 2, 
pp. 168-176, 1912. (See p. 175.) 

2 Mason, D. T. Management of western white pine. In Proc. Soc. Amer. Forest., v. 9, no. 1, pp. 59-68, 
i at Der Einfluss des Baumschwammes auf die Umtriebszeit der Kiefer. (Kritische Vergleichung 
der wichtigsten forsttechnischen und forstpolitischen Massnahmen deutscher und ausserdeutscher Forst- 
verwaltungen.) Jn Ztschr. Forst- u. Jagdw., Jahrg. 35, 1903, Heft. 11, pp. 685-690. 


4Martin. Die Umtriebszeit der Kiefer in den Staatsforsten von Preussen, Bayern, Elsass-Lothringen, 
Hessen und Anhalt. Jn Forstw. Centrbl., Jahrg. 54, 1910, Heft 7, pp. 363-387. 


FOREST PATHOLOGY IN FOREST REGULATION. 19 


Moller‘ touches upon the same point in a general way, without 
trying to give the problem a more solid basis by exact material. 
The following sentence is worth quoting: 

Whilst the mean annual increment of the stand is slowly decreasing, the mean 
- annual increment of decay is steadily on the increase. 

Here is the clue to the proper silvicultural valuation of cutting 
cycles or rotation on a pathological basis. The time at which a tree 
or a stand is to be cut may range from a comparatively low age to 
the age of maximum production of lumber, according to the special 
needs the forester has in view; but the upper limit of this range 
should not lie beyond the period at which the gain from increment is 
offset by loss from decay, irrespective of the ideal amount of timber 
a sound tree or stand might produce under favorable conditions. 
Not to cut a tree or a stand in which increment is offset or exceeded 
by loss from decay, where cutting is possible, constitutes an unsilvi- 
cultural act. Gilman ? informs us that silver fir in the Black Forest, 
Baden, Germany, ‘‘is unable to stand a long rotation, for after 100 
years the per cent of rotten timber increases greatly.’”’ Here, the ' 
influence of loss from decay on rotation is clearly shown; but it is to 
be noted that the loss factor is derived in a purely empirical way and 
is not based on exact studies. Hemmann® has published some 
interesting and exact studies on the damage done by Trametes pint 
in Scotch pine in a small area under regular management; that is, 
where the disease was partly eliminated by improvement cuttings. 

All this somewhat scanty European material, valuable though it 
undoubtedly is for transatlantic forestry, is of very little help to us. 
What holds good for the managed forest raised in a century of careful 
nursing can not serve for more than a clue in genuinely or practically 
virgin forests, whether they be located in the United States, in 
Canada, in Chile, in India, or in Siberia. Again we are confronted 
with the necessity of working out our own problems in our national 
forests. 

} INFERIOR SPECIES. 

Most of the timbered parts of the national forests, especially in the 
West, are practically virgin, seriously injured by fire, composed of 
even-aged or many-aged stands, and generally of more than one 
species, which are more or less exposed to heart rot caused by one 
or more specific fungi. 

1M@ller, A. Uber die Notwendigkeit und Méglichkeit wirksamer Bekimpfung des Kiefernbaum- 
\schwammes Trametes pini (Thore) Fries. Jn Ztschr. Forst- u. Jagdw., Jahrg.36,1904, pp. 677-715. (See 
Raith) E.C. V. Forest types of Baden. In Forestry Quart., v.10, no. 3, pp. 440-457, 1912. (See 
p. 452.) 


’Hemmann. Uber den Schaden des Kiefernbaumschwammes. in Allg. Forst- u. Jagdztg., Jahrg. 81, 
pp. 336-341, 1905. 


20 BULLETIN 275, U. S. DEPARTMENT OF AGRICULTURE. 


A systematic study of the relative position occupied by the heart- 
rot factor in the economy of the forest presupposes a knowledge of the 
morphology and biology of the specific fungi attacking the species of 
which the forest is made up. Morphologically, most fungi of economic 
importance are well known; biologically, there is much left to be 
learned. The susceptibility of each host species to specific attack, 
the age at which a given species becomes liable to attack by the 
fungi adapted to live on it, the age at which a given species is liable 
to suffer appreciable loss from this source, the relation of accessory 
factors in the tree and outside of it to fungus growth, the relative 
loss caused by each fungus in its specific host—all these are funda- 
mental problems which must be solved for every important fungus 
on every commercial species of our forest trees. So far, no definite 
and clear, comprehensive answer can be given to any one of these 
questions. 

In determining upon a suitable starting point in the overwhelm- 
ingly large amount of work before us, the question is that of deciding 
where such work is most needed at the present time. 

Leaving out of consideration such species as bigtree (Sequoia 
gigantea), which is never cut in national forests, and redwood (Sequoia 
sempervirens), which is hardly represented in national forests, the 
commercial timber of the national forests in the western part of the 
United States is composed of coniferous trees, such as pine, larch, 
spruce, fir, Douglas fir, hemlock, mcense cedar, and western white 
cedar. They constitute the goods the Government has to offer for 
sale. Of these the pines cause least trouble. Pine lumber is eagerly 
sought and pays good prices; moreover, the loss from decay is com- 
paratively small. In Government timber sales there is never any 
difficulty about pine timber; the more the Government has to sell 
on a given tract the better. Not so with the so-called “inferior 
species.”’ 

The term “inferior or undesirable species,’ as it is generally applied, 
is originally not a technical one. It is meant to designate those more 
or less heavily represented commercial species which suffer from a 
distinct prejudice on the part of the purchaser. If we could grow 
sound incense cedar, for instance, there would be a ready market and 
a good price for every foot, board measure, of it that the Government 
could offer on timber sales. Distinction should be made between 
species which actually yield technically poor lumber, even if sound, 
and species, on the other hand, which when clear and sound yield 
valuable material, but which are in general underrated by the pur- 
chasing public on account of the extraordinary prevalence of decay. 
An example of the first class is eastern hemlock. An example of the 
second class is incense cedar, which, although of excellent quality 
when sound, suffers from a very bad reputation among lumbermen, 


— —_— 


FOREST PATHOLOGY IN FOREST REGULATION. 21 


because it is so very commonly rendered useless by dry-rot or pin- 
rot. The numerically and economically most important species of 
the accessible merchantable national forests in southern Oregon and 
California are sugar pine, Jeffrey and yellow pine, Douglas fir, white 
fir, and incense cedar. To these may be added, for certain localities, 
lodgepole pine, red and Shasta firs, western larch, Sitka spruce, 
western hemlock, and western red cedar. Of the six main species, 
all three pines command good prices. They are comparatively free 
from heart rot. White fir and incense cedar are in general so badly 
defective that, as Clapp! states, they are ‘under present conditions 
almost a drug on the market.’’ Douglas fir stands in a class by 
itself. The value of its timber is well known; in fact, it competes 
with pine timber as far as quality for many purposes is concerned. 
On the other hand, Douglas fir is in a far higher degree susceptible 
to the attacks of several heartwood-destroying fungi, and, although 
it is not classed among the inferior species, the very prevalence of 
decay makes it less desirable than the pines, from a silvicultural 
point of view. 

Incense cedar and white fir are frankly classed as inferior. Whether 
this view is correct or not, we must reckon with it as a powerful factor 
of influence in all timber sales where these species occur. They are 
the lower grade by-products of the factory, the production of which 
can not be stopped; it goes on in spite of what we may wish or what 
we may do. The logical conclusion appears to be, then, to concen- 
trate all efforts on detailed and comprehensive studies of the properties 
of these by-products, desirable or undesirable, and to incorporate 
the results in a rational system of management, rather than to attempt 
to stop their production. The attitude of American foresters toward 
these and similar species is undoubtedly changing. There was a 
time when they were considered little better than weeds, to be gotten 
rid of as soon as possible and to be kept out of the forest wherever 
possible. This concept is giving room more and more to a considera- 
tion of how best to regulate the unavoidable reproduction of both 
species and how best to utilize the timber they produce. 

The so-called inferior or undesirable species have their very definite 
place in the ecology of the mixed forest, and many examples could 
be cited from European experience of the disastrous results of an arti- 
ficial change in representation of species and reduction of the mixed 
stand to a pure stand composed of an apparently more desirable 
Species, without due consideration to the local soil and climatic condi- 
tions. Greeley? seven years ago expressed the opinion that ‘‘it is 
pp. 168-176, 1912. (See p. 175.) 


2Greeley, W. B. A rough system of management for forest lands in the western Sierras. Jn Proc. Soc, 
Amer, Forest., v. 2, no. 2, pp. 103-114, 1907. (See p. 112.) 


28 BULLETIN 275, U. S. DEPARTMENT OF AGRICULTURE. 


both impossible and undesirable to eliminate these species altogether.” 
He specifically names white fir and incense cedar. Their aggressive- 
ness makes it impossible to eliminate them, even if this were desirable. 
But more than one species, not so many years ago considered inferior, 
has now come into its own. The history of the lumber markets of 
Europe and our own country shows conclusively that with closer 
utilization necessitated by the growing scarcity of timber, the value 
of lower grades, as well as of so-called inferior species, is advancing 
more rapidly than that of upper grades or more valuable species. In 
the case of incense cedar this evolution may be watched at the present 
time. Up to avery short time ago incense cedar was ‘‘almost.a drug 
on the market;’”’ now even very shan logs when sound. are utilized for 
pencil wood ond priced accordingly. 

Concentration of study on the inferior species, therefore, promises 
the most immediately applicable results. 


METHODS OF INVESTIGATION. 
CHOICE OF SPECIES AND SITE. 


Forestry is not interested primarily in the morphology and life 
history of a given heartwood-destroying fungus. Such studies, though 
indispensable and of the highest value, belong to an altogether differ- 
ent realm of science. The forester thinks in terms of trees, not of 
fungi; he concentrates on timber species to be protected or utilized, 
not on parasitic organisms, however interesting they may be from a 
mycological point of view. If forest pathology is ever to be of any 
value to practical forestry, all work and all conclusions must be 
focused on the tree, the species, as a producer of timber values and as 
a member of the forest community. 

The fact that the same species may be subject to serious loss from 
several fungi and that the same fungus often works differently in 
different host trees complicates the difficulties naturally connected 
with all work for which a basis first had to be constructed. Partly 
for this reason, the writer first worked on incense cedar, which, so far 
as known, has only one heartwood parasite, Polyporus amarus. The 
studies described in the following pages were concentrated on white 
fir, because its management presents, perhaps, the most embarrassing 
problem of to-day on the Pacific coast and because, in by far the greater 
number of cases, serious loss is caused by one fungus only, Echanodon- 
tum tinctorvum. 

After deciding upon the species to be investigated, the choice of 
the sites for the study becomes the main question. One single type 
will probably yield interesting clues, but the result can not with impu- 
nity be applied to all sites and types within the range of the species. 
It is clear that studies within what might be termed the merchantable 
range of the species must be most important from a practical point of 
view. But inside of the merchantable range the species is subject to 


FOREST PATHOLOGY IN FOREST REGULATION. 23 


so Many varying conditions with regard to soil, climate, admixture of 
the species, and representation that here again typical areas must be 
chosen for independent studies. The more diversified the types 
studied and the greater the number of trees per type and in the aggre- 
gate, the more reliable will be the results. 

The choice of the particular area to be studied is, of course, impor- 
tant. The unit of study should be representative, typical for the 
larger unit. In general it will not be difficult, with some care, to make 
the proper choice. 

The result of the writer’s studies, still unpublished, on the critical 
age of incense cedar served to work out the methods which should be 
applied in a modified form to the at present more important investi- 
gations on white fir. European precedent could not be used; Martin, 
Moller, and Hemmann worked on managed forests. New methods to 
suit our conditions had to be evolved. 

The only satisfactory result could be expected from careful dis- 
section and analysis of as large a number as possible of trees of dif- 
ferent ages. Unlike other investigative work, studies of this kind 
can not well be carried out on timber-sales areas where the actual 
felling and bucking of the trees is done by the purchaser. The 
purchaser is none too willing to cut trees containing rot unless he is 
compelled to do so; much less does he care to buck such trees, which, 
after all, are the ones from which we must expect most valuable 
instruction. He is not obliged to cut trees below a certain diameter 
limit, which, of course, can not be left out. All this is particularly 
true for the so-called inferior species, the handling of which often 
comes so near being a loss to the purchaser that any additional cost 
would work a distinct hardship. For the same reason it is impos- 
sible to have the trees on timber-sales areas bucked in odd log lengths, 


as dictated by the irregular and varying extent of the decay. As 


will be seen, a few of the notes used for this study are incomplete, 
because they had to be taken in connection with timber sales. 

It becomes necessary, therefore, to carry on investigations of this 
kind on representative areas chosen for the purpose and to have the 
systematic cutting and dissecting of the trees done by crews, involy- 
ing much work and a large expenditure. This way of handling the 
problem has proved to be the only feasible one; and, as long as 
immediate results may be expected, which if properly applied must 
lead to very considerable savings as well as to progress in silvicul- 
tural management and forest regulation, the expense and work seem 
to be justified. 


FIELD METHODS. 


Before the actual felling begins, notes are taken first on the larger 


forest unit of which the area to be studied forms a part, such as eleva- 


tion, climate, water table, soil in general, history (lightning and 


24 BULLETIN 275, U. S. DEPARTMENT OF AGRICULTURE, 


forest fires), composition, representation of species, ground cover, 
possibilities of future logging operations as a first step toward regula- 
tion, and local valuation of the species; more detailed notes of a 
similar nature then describe the particular type and stand which is 
the object of the study. 

When a new species is to be studied, trees of all sizes and all con- 
ditions must be cut. It is absolutely necessary constantly to guard 
against picking out trees either because they appear sound or because 
they are liable to contain decay. According to the attitude of mind 
of the investigator there will always be a tendency, conscious or sub- 
conscious, to think of the final result and accordingly to choose par- 
ticular trees for fellimg. The’ personal factor must necessarily 
influence the result of the equation and can not be warned against too 
emphatically. 

Correctness and accuracy in detail are the basis of any scientific 
work worthy of the name. Where the one chief aim is to substitute 
reliable figures for guesswork, to establish facts, from which con- 
servative interpretation may derive certain working rules, observa- 
tions and measurements can not go too far in detail and exactness. 
On the basis of experiences in the incense-cedar studies, a printed 
sheet was prepared, to be used in a loose-leaf binder of pocket size, 
in which a set of standard notes was to be entered. Each sheet 
contains the notes for one tree only. 

The first notes to be taken on a tree chosen for analysis are general; 
they are taken before the tree is felled. Slope, exposure, soil com- 
position, and moisture are taken for the individual tree; the next 
notes concern the outward appearance of the tree, crown class, as 
far as can be determined, condition of the bole, whether forked or 
leaning, presence and degree of fire scars, resin flow on butt or bole, 
swellings, sporophores of fungi, condition of the crown, development 
and state of health; in short, all notes that can and should be taken 
from the standing tree. During this time an assistant takes the 
diameter breast high and sets the fellers to work. The notes on the 
bole and crown are completed when the tree is down. They concern 
the presence of mistletoes or needle diseases, witches’-brooms of any 
kind, their number and relative importance, presence and extent of 
lightning injury, condition of top, and similar data that might have a 
bearing on the pathology of the species. It goes without saying that 
the tree is felled at the regulation stump height of 18 inches, never 
higher unless absolutely unavoidable. The assistant now measures 
the height of the tree from the ground and counts the age at the 
stump. This, of course, does not give the true age; but instead of 
adding, more or less at random, a small number of years corresponding 
to the height of the stump, it seems advisable to accept the count 
at the stump as the age. The fewer the figures based on an estimate 


FOREST PATHOLOGY IN FOREST REGULATION. 25 


that are included in our computations, the narrower will be the 
margin of error. Besides, in practical work, the age is generally 
counted at a stump height of 18 inches, and, since for all purposes of 
management we have to deal with the standing tree where diameter 
is the only indicator of age, it is of little importance whether the age 
counted is absolute, within narrow limits, as long as all figures are 
directly comparable with each other. Moreover, in practice it is 
impossible to have all trees cut at exactly 18 inches. With the 
greatest of care, the stump height will vary. It is an easy matter, 
where desired, to add a number of years corresponding to stump 
height as soon as reliable figures, which now are lacking, are obtainable. | 

The limbs and branches are now lopped off and the brush piled for 
burning. | 

In the bucking of the bole some judgment should be used, guided 
by the object of the study. We want to find all traces of decay in 
the bole and take exact measurements of them. Obviously, then, 
the aim of the dissection must be to open up the tree in such a way 
that no decay can escape the observer. It would not do, therefore, 
to buck all trees in even log lengths of the usual commercial measures. 
A straight, clean bole without any blemish whatever is bucked in 
16-foot logs, which then are individually split; this will, as a rule, 
bring out any hidden decay. Both the cross sections at the opened 
surfaces of the split wood must be searched very carefully for any 
abnormal sign. This makes full knowledge of the properties and 
aspect of the normal wood a prerequisite. In the beginning, there- 
fore, it is advisable first to study very closely the sound, normal wood 
of the species, until the operator is able to detect at a glance and 
automatically any deviation from the normal. The success of the 
study hinges upon the development of personal skill in judging wood. 
In order to prevent the dulling of this sense during the course of the 
work, check studies of perfectly sound wood will prove very bene- 
ficial, Any slight real or apparent deviation from the normal in 
physical properties or aspect, particularly in color, must be followed, 
of course, to its source. 

Trees without any blemish are rare; generally there is either some 
irregularity in form, fork, unusually heavy branching, or there are 
sporophores of fungi, badly healed-over branch stubs, swellings, de- 
pressions, catfaces, fire scars, lightning scars, or frost cracks and frost 
ridges. In choosing the proper places for bucking, it is generally 
advisable to start at the most salient malformations or defects; they 
will often lead to the focus of decay, if there is any. In case of fail- 
ure, the less prominent defects are investigated, and so on down the 
line until there is no doubt left that no decay is present in the bole. 
Particular attention must be given to branch stubs, which, by extend- 
ing through the sapwood to the outside of the tree, offer an easy 


26 BULLETIN 275, U. S. DEPARTMENT OF AGRICULTURE. 


entrance into the heartwood. After infection has taken place in 
this manner, the mycelium grows in the heartwood. Before sporo- 
phores are formed it is often impossible to locate the presence of 
the mycelium in the tree. This is particularly true for quite young 
fungus plants, and the possibility that the beginnings of decay 
may be hidden in a log, both ends of which are perfectly sound, 
must ever be present in the mind of the operator. It is impos- 
sible, except by mere chance, to detect the very first stages in the 
field. As soon as the fungus plant, the mycelium, has reached a 
certain stage of development, represented by visible alterations of 
the wood, there is no excuse for overlooking it. As a rule, the oldest 
part of the focus of infection shows the strongest evidence of 
fungus growth expressed in what we call decay. Decayed stubs 
are a valuable index as to decay in the tree, although there are cases 
where, for unknown reasons, the infection does not, or only very 
slowly, result in more extended decay. Duesberg ‘ has advocated the 
location of infected trees by the presence of diseased branch stubs. 
Such decayed branch stubs may also correspond to that stage of 
development of the mycelium just before the formation of sporo- 
phores through the stub takes place. In this case also decayed 
branch stubs will be most valuable in detecting heart rot in the bole. 

If decay is found, it is followed throughout its entire extent by 
splitting the logs with wedges and with the ax. To avoid this often 
very tedious and time-consuming work, splitting with black powder 
has been tried, with rather unsatisfactory results. In partly decayed 
logs the splitting is very irregular, and the wood surfaces are badly 
stained and blackened, the stain generally interfering with the inspec- 
tion of the wood. When the full extent of the decay is determined, 
notes are taken on the character of the discoloration or decay and on 
the stage of development, and the extent is carefully measured. For 
studies of this kind it will often be sufficient to note the extent in 
length in linear feet, under the assumption that in low-priced species 
any lumber that might be cut from an affected part of the bole will 
not pay for its transportation to the mill. In higher grade species 
the lateral extent must always be considered. 

This complete and detailed dissection usually allows the tracing of 
the decay to some point of entrance, whether fire scar, lightning 
wounds, frost cracks, or branch stubs. The result is entered on the 
sheet. Finally, any notes not specially foreseen on the sheet are 
entered under ‘‘ Remarks.”’ 

As a general principle, all observations that can be expressed 
numerically must be given in figures. It is essential that all esti- 


Fruchttriigern. In Ztschr. Forst- u. Jagdw., Jahrg. 44, Heft 1, pp. 42-43, 1912. Reviewed in Forestry 
Quart., Vv. 11, p. 251, 1913. ° 


4 
: 


FOREST PATHOLOGY IN FOREST REGULATION. ON 


mating should be reduced to a minimum. In order to render this 
unavoidable minimum, which undoubtedly constitutes a source of 
error, aS innocuous as possible, the operator must constantly be on 
the guard against any variations of his standard by which he is guided, 
consciously or subconsciously, and from time to time check up on 
this standard. The notes to be taken by’ estimate concern degree 
or grade. Soil moisture, seriousness of wounding by fire, degree of 
resin flow (whether light or heavy), condition of crown (for example, 
unhealthy color or thin foliage and the presence and degree of needle 
diseases in their bearing on the thriftiness of the tree), degree of dis- 
coloration of the wood—all these can be expressed in figures only 
with difficulty. Even if a scale of 1 to 10 is adopted for these pur- 
poses it is extremely difficult to decide whether the change of color 
of the wood under the influence of the fungus is to be classed as 6 or 7. 
The writer therefore has adopted a simpler system, which, while far 
from being exact, at least avoids gross errors and at the same time is 
graphically clear and sufficiently elastic to cover all cases of impor- 
tance. It expresses the information asked for on the sheets with the 
aid of crosses and dashes. A dash after ‘‘Fire scars,” for instance, 
js negative; there is no fire scar. One cross, x, is simply affirmative; 
there is fire injury, but it is not to be considered as serious. Two 
crosses, Xx, indicate that the fire injury is fairly bad, distinctly 
beyond the mere presence of an injury. ‘Three crosses, xxx, em- 
phasize the damage; the fire injury is unusually large and severe. By 
putting the crosses in parentheses, (x), or x (x), or by hyphenating two 
consecutive degrees, x-xx, intermediate grades may be given when 
desirable; and finally the last grade, xxxx, can be used in very extraor- 
dinary casesfor emphasis. In general, x, xx, and xxx will answer the 
purpose. Thus, the estimate is really reduced to a simple system of 
three grades, which allows for a more constant mental reference to 
the standard. Whenever necessary or feasible, special notes or meas- 
urements are entered after the crosses. This system is also used in 
our tables. With the exception given above, all these notes are 
taken by the chief of the party. Meantime, the assistant counts the 
age and diameter at every cross section, takes growth measurements, 
measures the width of sapwood and the length of the sections, and 
records such other data as may present themselves in the course of 
the work. 

In complicated cases, drawings or notes are added on blank sheets 
bearmg the numbers of the trees. 


PATHOLOGY OF WHITE FIR. 


The studies on white fir presented in the following pages are not 
meant to give definite results valid for the entire range of the species. 
They were primarily intended to develop the more practical methods 


28 BULLETIN 275, U. S. DEPARTMENT OF AGRICULTURE, 


to be employed and secondarily to gain reliable material to be used 
in a chain of similar studies on different types, from which conserva- 
tive interpretation may derive final conclusions. They are given 
here as examples only, as illustrations of the general considerations 
presented in this bulletm. Since making these studies, others on a 
larger scale and on different types in different parts of the range of 
white fir were carried out with improved methods durmg the summer 
of 1913. 

A short review of our present knowledge of the pathology of white 
fir will be of help in the discussion and interpretation of the data 
presented in this paper. 

White fir (Abies concolor (Gord.) Parry) can not be called a decadent 
species; on the contrary, it is very aggressive and possesses remarkable 
elasticity and resistance to injurious influences. Its tolerance to 
shade is well known. Not only does it survive dense shading to a 
high age but it responds readily to light and then reaches considerable 
diameter and height in perfect health, provided it has not been seri- 
ously wounded and infected. The oldest tree examined in this 
study was 258 years old; it was badly suppressed and but 67 feet 
high with a diameter breast high of 17.4 inches. In the trees tallied 
between the ages of 130 and 140 years, the diameter breast high 
varied from 8.8 to 30.7 inches and the height from 47.5 feet to 125 
feet. 

In speaking of tolerance which allows suppressed trees to reach a 
high age under the most unfavorable conditions and with a minimum 
of annual growth, the behavior of the species with relation to light 
is generally meant; but this toning down of the life functions of the 
tree, visibly expressed in growth, very often has nothing to do with 
lack of light. A tree may become suppressed to the lower limits of 
its tolerance by any agent severely attacking any of its vital organs. 
Of these, the organs of the crown are both most easily accessible and 
most sensitive; hence, the heavy damage resulting from a serious 
attack by insects devouring and killing the foliage or by leaf-inhabit- 
ing fungi. White fir is subject to a disease of the foliage caused by 
Lophodermvum nervisequium, which often kills all needles except 
those of the current year’s growth. ‘The loss in foliage surface, and 
therefore in photosynthetic capacity, may suppress a white fir just 
as lack of light would. Witches’-brooms caused by Peridermium 
elatrnum on white fir are not common. ‘They are very rarely of such 
development on the tree that they should be classed as an injurious 
factor to be reckoned with. Incidentally, it should be mentioned that 
the swellings and cankers so commonly connected with Peridermium 
elatinum on Abies pectinata in Europe are unknown in Abies concolor. 
On the other hand, very similar swellings and cankers caused on white 
fir by Razoumofskya abietina Englm. are extremely common. The 


FOREST PATHOLOGY IN FOREST REGULATION. 29 


actual connection is readily established by either the living mistletoe 
growing out from the swellings or by the small cuplike remains of 
the stem bases. The swellings render the affected part of the bole 
unmerchantable. When they break open into what are termed 
cankers, infection by fungi very readily takes place and a focus of 
heart rot forms, very much as in the case of Peridermium elatinum 
on Abies pectinata where Polyporus hartigu and Agaricus advposus * 
commonly start from cankers caused by the rust fungus. 

The mistletoe cankers very often are the cause of white-fir stems 
breaking off in a storm, just as Peridermium cankers affect Abies 
pectnata. This mistletoe is more generally found in the middle or 
lower parts of the crown; infection takes place only on the very 
- youngest twigs. 

Another mistletoe (Phoradendron bolleanum (Seeman) Coville) 
nests high up in the top. It often kills the leader; volunteers spring 
up, which are frequently killed in their turn. Considered in its rela- 
tion to the totality of leaf functions, the loss from a killing of the 
leaders can not be very serious, although it may count in combina- 
tion with other injurious agencies. The same is true for the host of 
minor parasites and injuries to which the peripheral growing parts— 
in contrast to the column of wood—are exposed. 

We have seen that the wood of the living tree itself is generally 
immune to attack from heartwood-destroying fungi as long as it is 
protected by bark and sapwood. The few exceptions, it seems, are 
of no great importance in the case of Abies concolor. Pholiota flam- 
mans is not uncommonly found in white fir and seems to take the 
place of Armillaria mellea. The exact damage done is still to be 
studied. Fomes annosus is not yet reported on white fir to the 
writer’s knowledge. Polyporus schwevnitzv is not common on the 
species. All other fungi causing decay can not enter the living 
tree except through some opening, as far as is known at present. 

In white fir, as in other coniferous trees, small superficial wounds 
are readily covered over with resin from the bark; this natural dressing 
does not allow fungus spores to germinate or the hyphez to develop 
after germination. Now, white fir is distinctly poor in resin. Large 
superficial wounds may therefore prove to be more serious. If the 
bark is destroyed, the cambium is killed and the sapwood dries out 
and cracks. Through these cracks air gains access to the interior of 
the tree and must in some way alter the chemistry and physics of 
the heartwood. The spores of heartwood-destroying fungi lodge in 
the cracks and upon germination may find a well-prepared substratum 
in the heartwood. Fungi, like all plants, make certain specific 
demands as to the chemical composition, water content, oxygen, 
etc., of the substratum they live on. Given the proper temperature 


1 Hartig, Robert. Lehrbuch der Pflanzenkrankheiten. Ed.3,p. 153. Berlin, 1900 


30 BULLETIN 275, U. S. DEPARTMENT OF AGRICULTURE, 


and the species of wood on which, for instance, a fungus like Echino- 
dontitum tinctorvwm (Indian-paint fungus), the most common de- 
stroyer of white-fir heartwood, can exist, its growth will still be 
dependent on the presence of heartwood of a certain character and 
on the water content of the heartwood. This is evidenced by the 
fact that decay is so commonly found in concentric development at a 
certain distance from the sapwood. The heartwood contains water 
in varying degrees, although it does not lift water lke sapwood. 
But there is nothing surprising or irrational about the assumption 
that the water content of the heartwood will depend more or less 
on the water movement in the sapwood. The water in the heart- 
wood of conifers is found in the membranes of the tracheids, not in 
the lumina. In a normal sound tree, heartwood of a given age and 
diameter surrounded by sapwood of normal width, corresponding to 
a certain crown development, will contain approximately a standard 
amount of water. Decrease in crown activity through some cause 
or another (suppression, injury to the crown, etc.) will soon be 
expressed in a rapid progress of heartwood formation, leaving only a 
narrow strip of sapwood, through which very much less water will 
move upward to the crown than in the normal tree. We may safely 
assume that the water content of the heartwood will change to a 
certain degree with the amount of water moved upward in the sap- 
wood. The water content of the sapwood changes, furthermore, 
with age, and also with the season. Both changes must also appear, 
although in a far less degree, in the heartwood. Minch! has em- 


phasized, in a series of very interesting papers, the relation of wood- . 


inhabiting fungi to the water and air content of the host tissues. 
Water-logged tissues are inaccessible to these fungi; a certain mini- 
mum of air, as Minch expresses it, must be present in the tissue in 
order to allow the development of the hyphe. 

Variations in the water contained by imbibition in the cell mem- 
branes must influence the degree of humidity of the air m the lumen 
of the cell itself; it is quite probable that this factor also plays a réle 
in the distribution of hyphe in the wood. 

What percentage of water in the cell membranes and of air in the 
lumina of the heartwood presents the optimum for the development 


of Echinodontium tinctorium and other similar fungi we do not know; 


but evidently there must be an optimum, a maximum, and a mini- 
mum. Any factor influencing the quota of water and air in the heart- 
wood must, therefore, be of greatimportance. Cracks in the sapwood 


1Miinch, Ernst. Die Blaufaule des Nadelholzes. In Naturw. Ztschr. Land- u. Forstw., Jahrg. 5, 1907, 
Heft 11, pp. 531-573; Jahrg. 6, 1908, Heft. 1, pp. 32-47, 33 figs.; Heft. 6, pp. 297-323. 

Miinch, Ernst. Untersuchungen tiber Immunitat und Krankheitsempfanglichkeit der Holzpflanzen. 
In Naturw. Ztschr. Forst- Land u. w., Jahrg. 7, 1909, Heft 1, pp. 54-75, 5 figs.; Heft 2, pp. 87-114; Heft3, pp. 
129-160. 

Miinch, Ernst. Uber krankhafte Kernbildung. In Naturw. Ztschr. Forst- u. Landw., Jahrg. 8, 1910, 
Heft 11, pp. 533-547; Heft 12, pp. 553-569, 2 figs. 


’ 


FOREST PATHOLOGY IN FOREST REGULATION. 31 


reaching to the heartwood admit air, and by evaporation change the 
water content of the heartwood; by oxidation, changes in its chemistry 
probably also take place. 

The change must necessarily be intensified, the more serious the 
injury. Wounds exposing the heartwood heal over very slowly, and 
the heartwood which receives all its water from the sapwood must be 
modified very markedly in its chemistry and physics, particularly in 
its water and oxygen content, by the long exposure to the air. More- 
over, from the time the injury happened until the time the wound is 
completely healed the heartwood is directly exposed to inoculation 
from spores of wood-destroying fungi adapted to white fir. Although 
the production of spores by a sporophore is enormous, by far the 
greater number are carried by air currents to places where they can 
not germinate for lack of moisture; many are intercepted by the 
natural screen (‘‘forest screen’) formed by the foliage and trunks of 
uninjured trees or by trees to which they are not adapted, and only a 
very small number finally land in the cracks of exposed sapwood or 
on exposed heartwood of white fir of the proper age. Of these, again, 
a very small percentage find temperature and moisture favorable for 
germination. ‘This explains the fact that so many trees, although 
badly wounded, are not infected. But it stands to reason that every 
year during which the heartwood remains exposed adds to the danger 
of the tree becoming infected. 

By far the deepest wounds are caused by fire. Although in white 
fir the danger in repeated fires feeding on the pitch flow following a 
first injury is comparatively slight, and although the lack of resin in 
the wood does not favor the hollowing out of the interior of the tree 
as it does in yellow pine, fire frequently causes very long wounds, which 
reach into the heartwood. 

Spores can gain entrance to the heartwood through open frost 
cracks. Low temperatures and sudden drops of temperature are 
common throughout the range of white fir. Inside of the range they 
are more or less confined to certain localities and zones. 

Lightning in white fir generally causes more or less superficial 
wounds. The peculiar injuries to be traced to lightning in white fir 
present many interesting features. Here we are only interested in 
injury which might lead to the infection of the heartwood. As in 
yellow pine, lightning sometimes tears long strips of bark off the tree 
and leaves the cambium and sapwood unprotected. In such cases 
both die and dry out, with the result that cracks in the sapwood lead 
into the interior of the tree. Smaller superficial lightning wounds 
locally kill the sapwood, which is very commonly attacked by second- 
ary fungi, which do not do very serious damage. However, logs with 
lightning injury of this kind are liable to be thrown out as culls, 
although they generally contain some sound heartwood. 


82 BULLETIN 275, U. S. DEPARTMENT OF AGRICULTURE, 


Other causes of serious wounds are comparatively rare. Occasion- 
ally a falling tree will brush off part of the bark of its neighbor. If 
the wound is large, the exposed sapwood dries out, cracks, and the 
heartwood becomes exposed. Very rarely a living tree shows signs 
of early girdling by rodents. Girdled trees as a rule are killed within 
a short, time. 

With very few exceptions the entrance of the fungus into the tree 
can be traced to one or more of the wounds just discussed. Occa- 
sionally, however, a tree showing no wounding at all is found to be 
decayed. In such cases the only means of entrance for the wood- 
destroying organism is through knots. 

White fir prunes itself very poorly; the wood of the twigs is tough, 
hard, and resistant, and the branches do not break off very readily. 
Later, dead twigs may break off; in the cracks of the wood of the 
stubs spores of fungi may find proper conditions for germination and, 


once established, use the pin knot as a bridge from the exterior of the 


tree through the bark and sapwood into the heartwood. This is par- 
ticularly true for twigs in which heartwood formation has begun. In 
this sense the opening afforded to fungi by a pin knot that is not 
healed over may be likened to a wound. The opening formed by the 
pin knot, however, is too small to materially influence the chemistry 
and physics of the heartwood of the tree. 

White fir is not exposed to a great number of heart-rot fungi. 
Polyporus schwevmtzw is not common. Polyporus sulphureus and 
Trametes pin are rather rare. The parasitism of Homes pinicola is 
not fully established, at least not in white fir. The writer has found 
it on thrifty sugar pine in central California, where it was undoubt- 
edly parasitic in the sense of attacking the sound heartwood of living 
trees through an open fire scar and extending toward the sapwood. 
There would be no incongruity in assuming that it may also occur 
parasitically on white fir; in fact, a number of observations rather 
speak for the correctness of this assumption. : 

By far the most serious danger to white fir throughout its range 
comes from Echinodontium tinctorwum Ellis and Ey. This fungus 
seems to be particularly adapted to Abies concolor and does not 
appear on many other species. In California it is, though not very 
often, found on Abies magnifica shastensis and also rarely on Douglas 
fir. This fungus must therefore be considered as the chief fungus 
enemy of white fir. The sporophores are easily recognized. They 
are rather large, from 2 to 10, 12, and more inches in width (measured 
horizontally from side to side where they are attached to the tree), 
distinctly hoof shaped, with a black, dull, cracked, rough upper sur- 
face, and a lighter, grayish, level under surface, which is thickly set 
with hard, coarse spines. In young specimens the under surface is 
whitish and rather dedaloid prior to breaking up into spines. The 


—S. Se lL ee 


FOREST PATHOLOGY IN FOREST REGULATION. 33 


interior of the sporophore is vividly rusty red. This rusty color is 
most characteristic of the fungus and repeats itself very often in the 
decayed tissues of the host. The sporophores are never formed on 
the bark of the tree; invariably they appear from the under side of 
stubs of dead twigs or branches, and commonly the rusty color can 
be followed through these stubs or knots. As the sporophore is 
nothing but the fruiting body of the mature fungus plant living in 
the heartwood of the tree, which alone it is able to attack, every 
sporophore is a certain sign of far-reaching decay in the tree. The 
typical rot may be characterized as a strmgy brown rot. Wood in 
this stage of decomposition is brown, with rusty reddish streaks, and 
becomes distinctly fibrous and stringy. Following the rot away from 
its maximum of development, we find wood still brown, with rusty 
streaks, but quite firm. Farther away, the brown color becomes less 
noticeable, the rusty color disappears, and finally we come to a point 
where the wood seems to be sound enough to be sent to the mill. A 
little care exercised in examination, however, will show in this seem- 
ingly sound wood the presence of small light-brownish spots and dis- 
colorations, particularly in the summer wood, intermingled with hor- 
izontal burrows, which at first glance could almost be taken for very 
shallow insect burrows. The burrows are not easily detected on a 
cross section. The small brown spots, which give the wood a faintly 
brown, mottled appearance, cause the entire cross section to be slightly 
darker than normal and discolored; but they show up very much 
more clearly in a longitudinal section. A small piece pried out of the 
end of the log with a hatchet or strong knife gives sufficient informa- 
tion about the real state of health of the log. This timber at present 
invariably goes to the mill and without doubt furnishes the lumber 
that, after being sawed, dries out and by becoming brittle causes the 
well-known prejudice against this species. It is often characterized 
by a peculiar sour smell and by a spongy consistency of the wood. 

Cull from decay in white fir, therefore, includes not only typical 
rot but also this discolored material, which, although not distinctly 
rotten, is already under the influence of the advance guard of the 
fungus mycelium and will become completely decayed later on. For 
this stage of incipient, or, better, latent decay, the writer proposes 
the term ‘‘advance rot,’’ which is used throughout this bulletin. 


DESCRIPTION OF AREAS. 


The three areas chosen for investigation are located on the Crater 
National Forest, in southwestern Oregon, all of them in the neighbor- 
hood of the Upper Klamath Lake, a large shallow basin with vast 
swamps, into which unusually large springs of clear cold water empty 
themselves. Very few streams of running water come from the 

98035°—Bull. 275—16——3 


34 BULLETIN 275, U. S. DEPARTMENT OF AGRICULTURE, 


surrounding mountains. Dense timber frames the swamps and ex- 
tends up the slopes to the mountain tops. The elevation of all three 
tracts varies from 4,150 to about 4,400 feet. Low winter tempera- 
tures and severe lightning storms are frequent in the entire region. 
Two of the tracts, the Pelican Bay Lumber Co. sales area and the 
Odessa ranger-station tract, are situated on the west shore of the lake. 
They are about 2 miles apart and present conditions so much thesame 
that they can be considered as one. 

The Pelican Bay tract on the west side of Pelican Bay lies, as far as 
the area covered by this study is concerned, along the slopes; the 
aspect is east to northeast. That is, it is exposed to cold wintry 
winds, sweeping unbroken across Upper Klamath Lake. We may 
expect frost injury. The volcanic soil is fairly deep and loose; the 
humus layer is rather shallow. There are no rock outcrops. The 
underbrush is composed of Ceanothus, manzanita, and some chin- 
quapin. 

The Odessa ranger-station tract is far less steep than the Pelican 
Bay tract. A considerable part of it is a gentle slope, almost level. 
The general aspect is north; presumably the tract is less exposed to 
sweeping winds of very low temperature. The soil is decomposed 
lava, but richer in humus than the Pelican Bay tract. Outcrops of 
rock are frequent. There are a number of large springs in the neigh- 
borhood. The underbrush is rather dense and is composed of 
Amelanchier alnifolia, Ceanothus velutinus, with some Salix sp.; the 
ground cover consists of Ceanothus prostratus, Berberis aquifolium, 
and Symphoricarpus racemosa. 

The third tract, the Otter & Burns sales area, lies about 15 miles 
north of the north end of Upper Klamath Lake. The tract is level, 
the soil very loose, sandy, decomposed pumice, with no indication of 
rock. Under the influence of the Fort Klamath Valley with its 
swamps, the atmospheric humidity is rather high, as is evidenced by 
the rich lichen flora, Alectoria fremont being common. Thus the 
immediate surface of the soil is kept damp, and litter disintegrates 
very rapidly. The humus is about 1 to 2 inches deep; the soil imme- 
diately underlying it is remarkably well drained. The rapid humifi- 
cation in the top layers favors the development of mycorrhiza on the 
roots of white fir in surface strata. White fir seedlings show a thick 
matting of mycorrhiza, confined to the same strata of a certain humi- 
fication, and a very long taproot seeking water. Yellow-pine seed- 
lings also develop a taproot, but the mycorrhiza rootlets are found 
at a greater depth than those of white fir. They are not as closely 
bunched as in white fir and are distributed over a larger area in a 
vertical direction. The underbrush is formed by Ceanothus velutinus 
of medium density, from 4 to 6 feet high, in a uniform cover. 


FOREST PATHOLOGY IN FOREST REGULATION. 85 


On the two tracts near the lake white fir is mixed with yellow pine 
and Douglas fir, a little incense cedar, and a very little sugar pine. 
On the Otter & Burns tract the stand is composed of yellow pine 
and white fir, with occasional lodgepole pine. 

On each tract conditions were more or less uniform, differences in 
elevation were negligible, and neither deep gulches nor steep slopes 
had to be figured with as disturbing factors. All in all, 160 trees were 
dissected and notes taken on all factors which possibly would have 
some bearing on the subject of this bulletin. In operating, the tracts 
were not clean cut; that is, not every white-fir tree in the area was 
felled and examined, since it was not the object of the study to estab- 
lish a cull per cent for that particular region. 

The data obtained are from selected trees. On the Pelican Bay 
Lumber Company’s sales areas the trees, of course, had all been 
marked by the Forest Service officers in charge; on the Otter & 
Burns sales area some trees were marked, and others were felled inde- 
pendently of marking. On the Odessa ranger-station tract all trees 
examined were felled for our special purpose. The representation of 
trees of different ages, diameter, and height classes on the three tracts, 
therefore, is not expressed correctly by the number of trees examined 


on each tract. 
LOCAL PATHOLOGY OF WHITE FIR. 


The pathology of white fir in the Upper Klamath Lake region is 
comparatively simple. Of injurious factors of an inanimate nature, 
fire, lightning, and frost are common. 

Very few species of fungi inhabiting living white fir are found on 
the three tracts. As we are mainly interested in the pathology of the 
the wood, the occasional occurrence of Peridermium elatinum and of 
Lophodermium nervisequium becomes an entirely negligible factor. 

Of heartwood-destroying fungi in living white fir, Echinodontium 
tinctorium is by far the most common, and sporophores are numerous. 


- About 75 per cent of all cases of decay were due to this fungus. 


eT 


Occasionally decay may with some certainty be traced to Fomes 
pinicola. In one case a sporophore of an Irpex was found in the 
decayed hollow of the trunk. Trametes pina is missing altogether, 
though found occasionally on neighboring sugar pine. Decay caused 


by Polyporus schweinitzi was found in several cases, never with 


sporophores. 

In other cases the decay was too indefinite to allow an identification 
of the fungus causing it. This is particularly true for the many cases 
of localized advance rot connected with scars from diffused lightning. 

The preponderance of Echinodontwum tinctorium, especially in con- 


- nection with really damaging decay, is so marked that in this study 


all important cases of decay are considered to be caused by this 
fungus. 


36 BULLETIN 275, U. S. DEPARTMENT OF AGRICULTURE. 


A study of the fungi destroying down timber lies beyond the scope 
of this bulletin. The only practical aspect of their activity lies in the 
fact that down timber, limbs, branches, twigs, and needles are decom- 
posed very rapidly. 

It is evident that all the points discussed in the preceding pages 
must be kept in mind in taking field notes. But this is not sufficient. 
Work of this kind has very much the character of an exploration; 


surprises and discoveries are possible at any point of the road, and it 


is therefore indispensable constantly to be on guard in order not to 
overlook any phenomenon worthy of observation. 


TABULATION OF DATA. 


The next step is proper tabulation of the data obtained. The three 
tracts were so close together and conditions so similar that they were 
considered as one, and all notes were combined. Separate interpreta- 
tion of the notes of each tract showed differences only in — The 
procedure was as follows: 

A first table was compiled from the field notes giving all schol 
data as well as all such data which might have a bearing on the 
subject of this bulletin. As we are particularly interested in the 
problem of the relation of age to infection and subsequent decay, a 
second table gave the same notes arranged progressively by the ages 
of the trees examined. This table formed the basis for further 
operations. 

The youngest tree dissected was 60 years old, and it is the first to 
show decay (Table I). The possible age limit of infection is therefore 
at least 60 years; it is probably lower. But in practical forestry we 
do not seek an answer to the question of the earliest age at which a 
tree might become infected, interesting as this is from a mycological 
point of view, but, rather, from what age may we with reasonable 
certainty assume that serious decay becomes so prevalent as to 
distinctly impair the merchantability of the timber. 

The tree in question has a diameter breast high of 10.1 inches; it is 
44 feet high. A healed-over broad scar still visible externally at 2 to 
8 feet above ground corresponds to an internal scar, reaching from 2 
to 10 feet, and was probably caused by lightning. The injury happened 
22 years ago and was distinctly superficial; the deterioration, in the 
form of a slight discoloration of the sapwood, follows this scar only, 
without extending any farther into the wood. This superficial dam- 
age does not render the affected logs unmerchantable. For practical 
purposes, therefore, such cases may be disregarded; they are negli- 
gible. In the interpretation of our material, the character and the 
degree of the damage must be considered with special relation to their 
bearing on the merchantability of the lumber. Not only the extent 
in longitudinal direction but also the distribution of the decay over 


FOREST PATHOLOGY IN FOREST REGULATION, — 37 


the cross section enter into the valuation of thisfactor. In the present 
study, the lateral extent of decay, the distribution over the cross 
section, was estimated, as it is in practical scaling. Actual measure- 
ments are difficult to take, on account of the immense variability of 
the decay. In Table I, decay which neither in lateral extent nor in 
degree was considered sufficient to seriously injure the merchanta- 
bility of the part affected was marked as negligible. The longitudinal 
decay was taken in linear feet, and the entire length was considered as 
affected, in order not to complicate the computation too much. We 
must distinguish between superficial decay of the sapwood and the 
more serious decay of the heartwood. Figures of superficial decay 
of sapwood are given in brackets (Table I, column 5). 

The next trees aresound. A negligible decay occurs in a tree 73 
years old. Its diameter breast high is 11.2 inches; its height 58 feet. 
The light decay started from an internal scar, caused by fire 23 years 
ago and healed over in 5 years, but it remained in close proximity 
to the scar without spreading. Again, a number of sound trees fol- 
low. Then the first more serious decay appears. 

The tree in question is 84 years old, its diameter breast high only 
8 inches, height only 45 feet. Both fire and lightning have played 
havoc with this individual. An open scar extends from the ground 
21 feet up the bole. The tree is quite evidently not in good health, 
the sapwood is very narrow, and the crown is lopsided and very short. 
Even in this case the decay follows more or less the open scar, but it 
is sufficiently serious to cull the affected parts in so small a tree; in a 
larger and thriftier one the damage would be called more or less local 
and a nominal deduction made in the scale. From a lumbering point 
of view this tree may be disregarded. 

So far, all trees considered had been either thrifty or not very 
seriously wounded. Here we have an obviously suppressed, un- 
_ healthy, and badly wounded tree; it presents at the same time the 
_ first case of decay that is not to be called negligible. The followimg 
trees are sound; then follows a negligible trace of decay in an 86-year- 
old tree, badly suppressed (diameter breast high 4 inches, height 13 
feet), grown in dense shade, with a remarkably small crown and with 
a healed-over frost crack, but no other wounds. After several sound, 
fairly thrifty trees follows a tree 87 years old, badly suppressed 
_ (diameter breast high 7.8 inches, height 39 feet), with a very short 
crown, wounded badly by fire and lightning (open scar from ground 
_ to 18 feet), and with decay following more or less closely the open scar. 

From these and the following trees, it appeared possible that with 
increasing age the crown class, or rather the degree of suppression and 
_ dominance, played a réle with regard to the extent and seriousness of 
the decay. Preliminary studies on incense cedar had given the same 
indications. It seemed desirable, therefore, to express this degree of 


88 BULLETIN 275, U. S. DEPARTMENT OF AGRICULTURE. 


‘\ 


suppression and dominance by a figure which would allow direct com- 
parison between trees of the same age. Height alone would be mis- 
leading. Volume table figures can not be used, since they are based 
on sound normal trees. The relation of height to diameter breast 
high, expressed in total volume, was thought to be a safer index. 
The object being to obtain directly comparable figures by ages and 
not the exact volume, the tree was considered as a perfect cone over 
the stump, at which we had taken the ages. From somewhat scanty, 
but individually reliable notes, the diameters at the stump (diameter 
outside bark 18 inches) were obtained, and from these and the height | 
the volume of the cone in cubic feet was computed. 


TaBLE I.—Fundamental data on the pathology of the white fir. 


Volume (cubic feet). 


Of rot, in- 
No. of tree. Age. Average cluding ad- Character of wounds. 
For each | for trees | vance rot 
tree. of same | (percent- 
age. age of total 
volume). 
1 2 3 4 5 6 
1 {Gat Sa pect ae ant 60 11.3 15(?) 1 [34.2] | Lightning. 
ROS secrets . hepa eae ee 69 25.1 19 — Leader healed in. 
1 ae pear 37. = eel 71 11.8 20 — No wounds. 
RSE ce: SLi ye aad tees 72 18.8 20 —_ Very slight lightning. 
MAC sicfee oe teae eee eee 72 CORY 20 oo No wounds. 
TAS SECE ski pte 73 18.5 20.3 12.7 | Fire; healed. 
Qe is ace cis Cee me moet 76 23.0 21 — Li ghtning. 
VES 3252.8 Fe tees 78 12.4 21.3 _ Very little lightning. 
NAY COPE ORS ed 4 Rall alias 80 31.4 23 —- Do. 
$305) cepa, ot). eee 81 45.5 24 — Several scars. 
ESS 3 oro Se ee ole oe uate tekors 82 29.9 241 — seh (?). 
SOM er es eee eh ree ras of 84 44.4 24.6 — No wounds. 
esate oe eaten See 84 8.9 24.6 82.8 | Fire, gt lightning. 
MOR 3s. 12g ees. 250% ee 84 25.6 24.6 — Little lightning. 
TSSe ae ke ep reise ceeae 85 (5) 25 — No wounds. 
PST Asa Letts Pes eA 86 33. 7 26 — Little lightning. 
a ee apa es Se 86 6.3 26 | Negligible. | Frost ridge. 
bah: }. Sspsee ysl ee 86 22.8 26 _ No wounds. 
TARY steer. Dae ioe soe ee tee 87 13.3 26.5 — Ligthning. 
149 catyi hs. .guyt pias 87 27.1 26.5 — Very little lightning. 
1: | RIA al PSS gh ne es 8 87 6.8 26. 5 82 Lightning with fire. 
ba! HO oe sh Be ey | & Ae OM 87 9.6 26.5 — Fire; healed. 
Be ne see te te es Pee 90 30.1 29 19.9 | Fire, healed; lightning. 
QOL ates Bee Cet SBN 92 128.1 30 — No wounds. 
1A: Heal i Saas Sk Le 92 10.2 30 a Very little lightning. 
1OS eS Soy ae eS 94 44.8 31 -= Fire, open; lightning. 
1 RI ae AOE, A RAS 2 yt 96 38.1 32.5 [4.53]| Fire, open. 
LTE. Fae se ES STL: Ee 96 32.9 32.5 — No wounds. 
WE I NG 5 0d urs tn 96 25.1 32.5 55.3 | Fire, open. 
(hia! 8 PR a PS ey 96 25.1 32:0 13.5 | Lightning. 
DAL atten ss neta ny se See aed 101 46.5 37 — Do. 
120 AGO oT. 102 22.3 38 16.8 | Fire, open. 
NES A) SRR WA id a 103 34.2 39 61 Fire; lightning. 
AGB) Sis TY BOS ih SAE 103 35. 2 39 _ No wounds. 
1 ST SY Ne 104 25.5 40 [2.39]| Lightning. 
TOAD LEN: LORE Se 104 25:15 40 71.8 Do. : 
1 Rc DL i I 104 68.2 40 47.6 | Old girdling; lightning. 
12635) ee Pa ee 105 20.7 41 43.5 | Fire, open. 
1 ROE iN ety es SBR th 105 90.3 41 -—- No wounds. 
20 de eRe RE ee 105 32.2 41 _ Do. 
AD cle Sots paceloae ree emig Bee 105 58 41 _ Do. 
BHM EOE ERLE RY Ye 105 52 41 — Do. 
102. cca ence estan ween 2 106 29 42 46.9 | Fire, open. 
QU AS MCS LEE E 106 48.3 42 Traces. Lightning. 
(af Pee eee ae es 107 17.0 43 45.5 | Falling tree. 


1 The use of brackets ([]) in column 5 indicates superficial decay of sapwood. 
2 The letters a and b indicate two distinct foci of decay in the same tree. 


FOREST PATHOLOGY IN FOREST REGULATION. 


39 


TaBLeE I.—Fundamental data on the pathology of the white fir—Continued. 


No. of tree. Age. 


Volume (cubic feet). 


tree. 


Average cluding ad- 
For each | for trees 


Of rot, in- 


1 2 
(oo emo apor ee or 107 
LOO et Peer Been: poe aEeee 107 
Le creeieicting Hor epee Been EEE 107 
eae ofa wiaia Ycjn ~'- 107 
22) Bac A Opec eae ame 108 
ee sani are win. 3 2 109 
Us = 5 oe Re i I 110 
ete Sb eine oa)aiclm\~ «> > =\-\- 110 
(Dena See eee ae 110 
(Us Oe AOR Sa oe ne ee 110 
eee naeseeecs voces <=. 110 
Ue See ae re 110 
epee ts cases a 111 
USE Cae eee oe eee 111 
aman aeaateee 5s = 22 112. 
Ds oe dbe46 3S eee see 112 
3h he Com Coos See eee 112 
Elbe 2 Ee eee 113 
Loot ede ee 114 
Ofc). Same raes AS20052. 4 116 
OO aoe er 116 
hos conn Sh See 118 
LC err 118 
UO Ge aA ot hee 119 
(OL Ge) A 119 
Wa 2 ee 121 
Bee es Dapels ass sma =< <- - 122 
Diskctsy daue See oe 123 
Oo ee ts leken niais <i -j2's = «6 123 
US St ee ee 123 
eR cia cl az.cicis -.0'o = 124 
BR ASA Soe eee eee 124 
Ue AS heeee tee 124 
SB sis Seo Le Cee a 125 
JUN 125 
Gee atetig. chest ah ----- 126 
(ae 2 Ba Se 129 
FA on fin. Bape ae 130 
Site Gace) epee a aeeeeebam 130 
Gi. eA SDe 8 68 eee 131 
Ol SE I SL ae 132 
A OR AS EEE eee 132 
1a ES oe eee 132 
GU lok IEEE A 2s aes ae 133 
Ue eae Oc See eee 133 
OR Ua on tie wae ee ee 134 
Wish RS yt: Sas SCR 135 
eS ae 135 
Bie elle Se ona < = a= 3 136 
Lin ey BS hy 4 See 136 
lo a eee ee 136 
Ug 45-6 4s a hae ee 137 
CAE ee 137 
ieee LES Coe ree ars 138 
OO ee 138 
ioe a. 02S Ae eps 140 
(Se Sete a ae 140 
JUSTE ee ae 140 
ele dea 140 
os See Ay 4's. bo 140 
weve dee 140 
Coa Se eae ee ea 140 
6) GUE eae 141 
Urs As ots ai. Yr. 143 
Nhe aA es eae! 144 
eS ai 146 
LINO SLR ee a 146 
LNCS BENE ae eae 148 
PE ere Sete Sioa iets ogni: 148 
OZ SPSELCUEIS - Sp Stic 22 sc 149 
Pe Miate aN kx ciel anid ae a mn « 150 


55.0 


on 
BH NOMMOHUNRWRORWROH RE 


ror 
A 
ox 


vance rot 
ofsame | (percent- 
age. age of total 
volume). 
4 5 
43 [92.2] 
43 — 
43 — 
43 [9.12] 
44 == 
45 _— 
46 68.5 
46 — 
46 _ 
46 58. 7 
46 — 
46 — 
47 2300 
47 — 
48 42.9 
48 42.1 
48 SL 
49 [23. 9] 
50 -~ 
52 [Trace.] 
52 40 
53.5 _— 
aoup — 
54 — 
54 100 
56 — 
57 — 
58 89.0 
58 [8. 8] 
58 77 
59 29.0 
59 60.0 
59 Negligible. 
61 
61 58. 1 
62 82.1 
65 80.3 
66 77.5 
66 32.4 
67 93.7 
69 — 
69 — 
69 65.3 
70 34.6 
70 — 
71 21.8 
73 42.0 
73 60.7 
74 95.6 
74 —_ 
74 76.9 
76 — 
76 85.3 
78 — 
78 — 
80 96. 4 
80 _ 
80 132.7 
80 100 
80 — 
80 
80 133.5 
82 00 
86 51.2 
87 — 
90 [27.7 
90 88] 
94 70 
94 — 
96 60.1 
97 = 


Character of wounds. 


Lightning. 

Little lightning. 

No wounds. 

Frost crack. 

No wounds. 
Do. 

Fire, open. 

No wounds. 

as ae 


0. 
Little lightning. 

Very little lightning. 

Fire, open. 

Fire: little lightning. 

Twin healed in; frost crack. 
Fire, open; lightning. 
Frost crack. 

Fire, open. 

Fire: lightning. 

Fire, open. 


No wounds. 
(?) 


Fire. 

Fire; lightning. 
Lightning. 

Little lightning. 

Frost crack. 
Lightning. 

Fire, open. 

Fire. 

Frost crack; lightning. 
Fire, open; ‘lightning. 
Lightning. 

Fire, open. 

Frost crack. 

Fire, open; frost crack. 
Light ning. 

Fire, open. 

Frost crack. 

No wounds. 


Do. 
Frost crack. 
Fire, open. 
weal Ta 


No wounds. 
Fire; frost cracks; lightning. 
Frost crack. 
No wounds. 
Do. 
Do. 
Lightning. 
Do. 


Frost crack. 

Fire. 

No wounds. 
Lightning. 
Lightning, severe. 
Lightning. 

Fire, open; lightning. 
i he 


Falling tree; frost crack; lightning. 
No wounds. 

Fire. 

Frost crack; lightning. 

Frost crack. 

No wounds. 

Fire, open. 

No wounds. 


40 BULLETIN 275, U. S. DEPARTMENT OF AGRICULTURE. 


TaBLe I.—Fundamental data on the pathology of the white fir—Continued. 


LLL 
Volume (cubic feet). 


Of rot, in- 
No. of tree. Age. Average cluding ad- Character of wounds. 
For each | for trees | vance rot ; 
tree. of same | (percent- 
age. age of total 
volume). 
1 2 3 4 5 6 
Db bcinet Boker eRe eee 150 123.5 97 81.5 | Frost crack. 
DAR eee cee & 2 Sen ee 150 45.6 97 55.5 | Fire, open; lightning. 
ASIP loge Mota wa 150| 112.5 97 68 Do. 
Ble acute eek ese regen 151 16.6 99 41.3 (?) 
SopmeeLesree Oboes eRe 152 192.5 101 58.1 | Frost crack. 
Bee ee acewciccke time me 152 75 101 15.7 Do. 
GLGS Ae pes ee She ee 155 235 107 63. Fire, open. 
=) bapa Ed eae cee g PILE eng ® 155 121 107 36. Oo. 
bi ae Se 155 37.7 107 Negligible Lightning. 
ro a ae See MAN Mea Oats AL 156 380 109 36. Fire; frost crack. 
QL ee ee ame Soe Se eens 156 96.5 109 32. 3 Do. 
Die <'aihae a Laas 159 152.0 109 No wounds. 
PG AC cee Miri ke eve sees 160 224.5 116 73. 7 +| Fire, open. 
ts DEP. tee 160 26.8 116 98.5 Fire, open; lightning. 
VS... 2...) seed tee ceed 161 68.6 118 = Lightning. 
LO0Re ee Fe ese oe des) lag t 161 68.2 118 89.4 | Frost crack. 
PIG ocr ewe ee Foe 162 38 121 oo Lightning. ' 
AT ephats saber eench aceme 163 122.5 123 — Notes eet 
il Wee ee ce ce 0 163 106 123 82.9 | Fire, oper 
Bay Seteus sce eee Lenn ce oe 164 417 125 25.5 | Frost on (healed); lightning, 
Bie fas See eR sy eh ae ee 165 (?) 127 |Incomplete.| Fire, open. 
Eee oa Aa se cet Cee ee 165 128.5 127 53.4 Fire: lightning. 
A eats helo bh RES Ane g A a 166 57.2 129 (?) Notes missing. 
Dau eE Ee reine tie foe ee eee 166 171.5 129 — No wounds. 
PASTS Sh Segre SA eR 168 179 134 —_ Fire. 
ey OR I ST Sana A MORI ao 169 291.7 136 6.8 | Fire; frost cracks. 
See eee Cee cee secs sees 170 328.5 138 53 Fire. 
Dies eee rts RP RMA 170 121 138 87.4 | Frost crack. 
OU eer sone bat attr wewa ese 170 123.8 138 67.2 | No wounds. 
(rH aa ed ea bi 175 68.0 150 47.1 | Fire, open. 
sO 5 RE A oT A 175 68.0 150 16.4 | Lightning. 
5 (Tee Sets tia dmetiteae Td apse A 178 PADI 158 — Frost crack. 
Doe hycc atest. Eee 178 127.7 158 [5.1] | Lightning. 
1 a aia onl te AE Dae Lei AL 180 133 164 16.7 | Fire, open. 
(UR aR Bie sey tN ae la 183 100 [166] 39.5 | Lightning. 
Fe SpE YS et ML RG EE A 6 185 148.3 [166] — No wounds. 
06.27,...2. % Cee Sout) cdliSkie/| sar. 5 [166] 53.6 | Fire, open. { 
We ee tant eee 186 42.85 | [166] ae Lightning. 4 
GOs oe oe ee ue eee 189 64.4 [168] - Frost ridge; lightning. pt 
BO Petry ou 7 eee 191 | 546 [168] 52 Fire. 
Ly Rae a baie Gating « 192 110.7 [170] 95.5 | Fire, open; frost cracks. 
I ap Ud Settle rte lies Bak Fe 200 115.7 [180] | Negligible. | Frost crack. 
Lap eee eee ot) 2 eae 200 26.0 [180] 100 Fire, open; lightning. 
WOLMee ner cat coc tte a ee 221 196 [190] 100 Frost crack; lightning. 
Samer ta roe ARKO | 932 | 235 [200] 71.3 | Lightning. 
Ck cael iA ae Be. 258 46.7 [220] [100] Fire, open; frost cracks; lightning. ~ 


These volumes are, of course, not directly comparable with each 
other; they have a meaning only when individually compared with 
normal volumes for the same age. It was necessary, therefore, to 
curve data collected on normal trees, such as were selected for vol- 
ume tables in larger numbers on the same area. The most reliable 
portion of this curve lies between 80 and 180 years. The relation of 
the actual to the average volume of trees of the same age we may 
use as an index of suppression or dominance of the individuals in : 
question. 

The volume of the decayed part of the bole was figured as the 
affected part of the cone. But instead of giving the decay simply in 


FOREST PATHOLOGY IN FOREST REGULATION. 41 


cubic feet, making constant reference to the total volume of the 
tree necessary, the volume of the rot was expressed in percentage of 
the total volume. Advance rot—that part of the wood already under 
the influence of the mycelium—is included. It must be kept in mind 
that all figures given under this heading (column 5) are therefore 
likely to be high. To be on the conservative side, all measures of 
decay were taken very carefully, and in all cases where there was 
any possible doubt the uncertain part was measured as decay. But 
since the same procedure was followed consistently the results are 
directly comparable. 

Table I gives us our working material in figures. Column 1 shows 
the individual number of each tree from the field notes and is given 
only for convenience of reference, the trees being arranged in the 
order of their ages (column 2). Column 3 shows the actual or total 
volume in cubic feet of each tree, considered as a perfect cone. 
Column 4 gives the volume in cubic feet for the average tree of the 
same age. Column 5 shows the volume of rot (including advance 
rot) in cubic feet expressed as a percentage of the total volume of 
the tree. Column 6 shows the character of the wounds. 


CONDENSATION OF DATA. 


It proved difficult to interpret intelligently this mass of figures. 
If there existed any relation between decay and possible influencing 
factors, it certainly did not appear very clearly from this table. 
It became necessary to simplify and condense the material. 

Instead of expressing dominance or suppression by the relation 
of the actual to the normal volume in figures, the system of crosses 
described above for the field notes was used. Three classes were 
adopted—dominant, intermediate, and suppressed. Those volumes 
which came closest to the average were considered intermediate 
and entered in the table with one cross, which expresses the affirma- 
tive; a dash signifies negation. In the intermediate class therefore 
there can be not more than one cross. The deviation from this 
average shows in the two other classes, and as here all degrees are 
possible, the degree of suppression or of dominance is shown with one, 
two, or three crosses. Thus, three crosses under ‘‘Dominance”’ 
mean that the tree is as far beyond the average as is possible in that 
locality. On the other hand, one cross under ‘‘Suppression”’ means 
that the tree is decidedly suppressed, two crosses that itis badly 
suppressed, and three crosses indicate the highest degree of sup- 
pression. This classification is admittedly arbitrary; it seemed to 
answer the purpose, however, and has so many advantages, with its 
possible grades and its graphical clearness, that it may be retained 
until some better method is devised. (Table II, columns 3, 4, and 5.) 


42 BULLETIN 275, U. S. DEPARTMENT OF AGRICULTURE, 


To reduce the figures in column 5 of Table I to simpler symbols 
was more difficult. Here the entire affected part of the cone for 
practical purposes was considered as cull, including the sapwood. 
In reality, there are, of course, all gradations from a slight discolora- 
tion of the sapwood following a long lightning scar or a number of 
smaller scars to complete destruction of the heartwood by decay. 
In order to simplify this column and to bring out more forcibly its 


relation to influencing factors, the writer tried to reduce the percent- — 


age figures to ratings, applying the system of crosses used throughout 
this study, taking into account not only the volume percentage of rot 
in cubic feet, but also the character of the injury with regard to the 
degree of rottenness. Thus, one cross in parentheses, (x), signifies 
slight and negligible local discoloration; one cross (not in parentheses) 
shows distinct rot, but affecting not more than about one-third of 
the tree; two crosses, about two-thirds of tree affected; three crosses, 
more or less of the entire tree affected. In each case, the character 
of the decay as indicated by the detailed field notes was given due 
consideration. This explains apparent discrepancies between decay 
rating and decay volume in the percentages in Table I, where the 
affected part of the bole was considered as cull for the entire length 
of the decay. In decay rating, the actual loss in merchantability 
was expressed according to the character of the rot and its extent. 
This valuation of the decay, it is true, is necessarily somewhat arbi- 
trary. It is really the condensation of carefully taken field notes and 
measurements and must serve until a more satisfactory method can 
be found. Where general relationships only are concerned, as in 
this case, our symbols may be sufficiently correct, provided they are 
based on exact figures and reliable field notes. (Table II, column 6.) 

In order to insure a higher degree of reliability for the decay-rating 
symbols, the operation was repeated some time later without con- 
sulting the results of the first. With insignificant exceptions, both 
ratings were identical. 

In much the same way the character and degree of wounding was 
reduced to a system of crosses. Plainly, this can be done only from 
field notes, which were generally amplified by actual measurements 
of the size and extent of the wound. The chances of inoculation 
offered by a wound decide its rating. That deep wounds, particu- 
larly such as have remained open for a longer time, are rated higher 
than small superficial injuries, soon healed over, is self-evident. The 
system of crosses is the same as heretofore explained. (Table I, col- 
umn 7.) 

‘The next column (Table II, column 8) indicates the means whereby 

the fungus entered the tree, as evidenced by the analysis. 


FOREST PATHOLOGY IN FOREST REGULATION. 


43 


Taste II.—Condensed data on the pathology of the white fir. 


——<—_—_— | ————__  — ——————_ fF | | | SSS Ss 


107 
107 


110 


110 


112 


112 


114 


Degree of dominance or 


of suppression. 
Domi- an Suppres- 
nance. | “ate sion 


is 
ta 


ert el | 


si 
‘i 
va 


TERRE ARELLAL ER Ran Oana: 


MIPIM RP Li bles 


HITT 


re ere eee eee eae et eee el Pt 


ara T Tt eid 


Peretti 


ILL LIB Heo) x 


> 
a 


[Homo RI HRI PIB Bey 


Decay | Wound! Infection traced 


rating. | rating. 


—. —$——_ |J —_-s | | 


wee ee ene 


weer eces 


ee Bee 


— 
go 


Fire; lightning. 


Frost crack. rates 


Lightning; fire. 


Fire, open...... 


Fire, open......- 
Lightning....... 


Fire, open...... 
Fi 


Lightning. ..... 
Fe ae (6 (0) Sees 
GarGintes . ocd = 


Fire, open...... 


Fire, open...... 
Lightning. ...... 
Falling tree..... 
Lightning. ...... 


Frost crack. .... 


Fire, open...... 


Fire, open...... 


Fire, open...... 


Twin and frost 
crack. 
Lightning. ...... 
Frost crack. .... 
Fire, open...... 


Appar- 


ent 


condi- 
tion of 
crown. 


Ne eee 
cit at anLst sit allatanLalalta! 


Yee SSO” 


NNN 
ea — Se 


is 


Co Feet as 
Run nl aRe ean ® 
~~ een Sl 


‘aiatlatalalalaltal 


-_ 
~~ 


a 


-—- 
‘a 
— 


CLLLCLCLLML LIL 
a — 


Remarks. 


10 


Negligible; advance 
rot. 


Negligible. 


Advance rot. 


Negligible. 
Advance rot. 
Do. 
Advance rot. 
Open 22 years. 
Advance rot. 
0. 
Almost completely 
girdled 82 years 
ago; wound open 


31 years; mostly 
advance rot. 


Negligible. 

Advance rot. 

Advance rot local- 
ized in scars. 


Negligible. 
Mostly advance rot. 


Rot following two 
very long open 
scars. 

Advance rot. 

Very slight advance 
rot. 

ar advancerot. 


0. 
Little typical rot. 


44 


a a) ee — 


BULLETIN 275, U. S. DEPARTMENT OF AGRICULTURE. 


TaBLE II.—Condensed data on the pathology of the white fir—Continued. 


140 


141 
143 


144 
146 
146 


148 
148 
149 
150 
150 
150 
150 
151 


Degree of dominance or 
of suppression. 


IHIRIIBR 11g 


ae eee SS ee ee it bas i 


L1H I 


ile 


| | 


ae eo ing ie 


Decay | Wound 


rating. | rating. 
6 7 
— xX 
p.0.4 
Bk De (x) 
Sate be - xx 
x OOK 
ees. 8 p. 
nod 5.8 
-- x 
ox 0.0.4 
x p.@.< 
ay <x 
— 5. 
- SAS x 
xx b.@O. 
2.0.8.4 BO 
XxX 0.2.0.8 
xx 5. B1O.¢ 
xx Xxx 
Xxx xx 
xxx >o-d 
x po.0.4 
TE ie x 
x x 
x — 
2.06 XXX 
Xxx XxX 
b.0.0.¢ — 
xxx P.3 
ASU ASAE p.@.6 
aaa Se x 
2D. D.S.6 
Dk 2.0.0 .¢ 
XXX 56,0. 
fees 21. x 
ROKK: 2.0.0: 
x b:O.0.4 
p.2.@. Cs Ieee. ©. < 
xx P.O 
x p.©.¢ 
xx D:@.D. 
2.86 OK: 
POX: OK 
b:@.0.¢ 2.0.18 
xx xxx 
xx xXx 
xx xx 


Infection traced 


Fire, open. . 


Fire (2), with 
neha 


Frost crack..... 


Fire, Open. 5... a: 
Wine: | <5 eee ee 
Frost crack. . 
Fire; lightning. . 


Fire Open. 4 

Frostcrack.. = 4: 

Fire, with frost 
crack. 


Lightning....... 
Fire, open... . 


Frost crack. ... 


Frost crack. . 2. 


Fire, open.... 


Fire, with frost 
crack. 
Frost crack..... 


ae 


wee ee eNUe we eee eee 


Frost crack; 
wounds from 
falling tree. 


Livhining and 
frost. 
Frost crack..... 


Fire, open....... 


Frost crack. oP 4 
Hire peers lead 


Appar- 
ent 
condi- 
tion of 
crown. 


bd bd Pd dO Dd Od 


bd bd 


ELL: Pa bd Pd 


tal 
F cee. 
“2 
4 


va 


= 
~ 
— 


HEE mo 


ho 


MAM MMH MH 


Remarks. 


10 


Negligible. 
Mostly advance rot. 


Advance rot. 


Much advance rot. 

Advance rot; negli- 
gible. 

Very long scar. 

Little advance rot. 

Advance rot. 


Much advance rot. 

Sporophore. 

Two very bad burns 
held open by frost 
oman or 85 years; 
sporophore. 

Much athe 'p Binoy 
young sporophore 

Very a open fire 
scar. 


Much advance rot; 
2 sporophores. 
Mostly advance rot. 


Advance rot. 
Slight advance rot. 
Much advance rot. 
Sporophore. 
Sporophore. 


Much advance rot. 


Sporophore. 
Slight advance rot. 


Tree almost killed at 
age of 81 years; 
Tn advance 
ro 


Much advance rot 
near wounds. 


Advance rot. 

Much advance rot 
in scars. 

Small sporophore. 


Rot following scars. 


Much advance rot; 
small tree, 


FOREST PATHOLOGY IN FOREST REGULATION, 45 


TasLeE II.—Condensed data on the pathology of the white fir—Continued. 


Degree of dominance or 


of suppression. Appar- 
No. Decay | Wound] Infection traced | °@% 
of | Age ‘a y ti t condi- Remarks. 
tree Inter Pets. | Totus a tion of 
Domi- | inedi- | SUPPFes- crown 
nance sion. 
ate. 
1 2 3 4 5 6 7 8 9 10 
8 | 152 2.0% — — xox x Frost crack.....- x Two sporophores. 
9| 152 — — 2.0.8 bg p:@. a | oe (3 (eae x Scar long healed 
over. 
13 | 155 —_— —_— 0.0.4 xx xxx | Fire, open.. x 
31 | 155 x — ~= x xxx | Fire............. x Slight advance rot. 
117 | 155 — — Exx = xx Lightning....... 0.0.4 
156 | xxx _ — xx xxx jj Frost‘crack....-. x Much advance rot 
and shake. 
91 | 156 — _— x x xxx | Fire, open... BO. 
27) LOL | XXX _ San) Oe Pee = == x 
12} 160} xxx — — XxX KKK? re! 2 VS B. 
93 | 160 — —_ 8.0.6 xxx XOX | HBIRS, OPN. 28. x 
118 | 161 _ — bo. Ta a) (A oa Se me = p.9.0.2 
160 | 161 — — pO. 0.4 axx xx Host erack. so... xxx | Sporophore. 
116 | 162 — — KOK, pei ea ae x a x 
47 | 163 — x: Sp reese x — x 
81} 163 _— = x 0,0.0.6 xxx | Fire, open... xxx 
84] 164] xxx —_ — xx 2.2.6 Piette wy. 2k x Small sporophore. 

3] 165 (?) (?) (?) xx ER BARS. soodase ele. >¢ Notes incomplete; 
», Fe B -265 
inches. 

51 | 165 —_ x _ xX, p.&. gay || ee C0 (0 ee eR x Much advance rot. 
24} 166 — — 2.0.0.6 x (?) (?) x Notes incomplete. 
32 | 166 xx = Raat WP as: eeete — — x 

29} 168 p.0.4 oa eS Ae (x) — x 

$2)| ,169:,| 4 xxx _— — x XK Gl Kn Othe aa (x) | Very thrifty. 

8| 170| xxx — — xx XX Biretha eae. x(?) 

57 | 170 = — oe 2.0.0.8 p.®.¢ Frost crack....-- xx Five sporophores. 
67 | 170 _ — x eK _ IAMOU IM cio. x Small sporophores. 
64-a | 175 _ — 2.O.@.6 00.6.6 xxx +| Fire, open... x 
64-b | 175 — — Xxx xx xxx | Lightning....... x oT rot; small 
ree. 
36 | 178 XxX — | es eae x x 
52 | 178 — _— x _ x Lightning fs x Advance rot. 
77 | 180 — _ xx x 5. 2.@ dae iia) 2; Sa SS x Advance rot and 
shake. 
71} 183 =— — OR x xxx} Lightning... ..': 3.0. Advance rot. 
34 | 185 ae — Git) (Me Ame: — = m4 
95} 185 — — 2.6.4 xx xxx | Fire, open... x 
107 | 186 — — 3.2.00, | a ae xx x 
66 | 189 — —_ 3-©.0. Guus | Paella p.o.< — x 
39 | 191] xxx — — x 6 oR |.) a x Fire 110 years ago. 
86 | 192 — — DO. KON: xxx | Frost crack.. x Large sporophore. 
14} 200 = — DO. — De ae Oe PEC aeeDe |e 2.0.2.4 
142 | 200 — _— XxX XxX Koc ies ok og HASSE xxx | Much advance rot; 
small tree. 
73 | 221 _ x = XXX xx Frostcrack with | xx Four sporophores. 
lightning. 
59 | 232 x — — 2.3.0. x Lightning....... (?) Much advance rot. 
141 | 238 — —— XXX BGO. xxx | Fire with frost | xxx | Mostly advance rot 
crack. with shake. 


Another column, concerns the apparent condition of the tree (Table 


II, column 9) and indicates the appearance of health of the crown, 
taking the healthy, thrifty tree as normal (indicated by one cross) 
and marking the degree of deviation from the normal in the usual 
way. Thus, one cross in parentheses, (x), means that the tree is an 
exceptionally healthy. one; two crosses (not in parentheses) indicate 
that the crown is rather poor, either in development or that the color 
is abnormal, etc.; and a tree having a very much underdeveloped 
and sickly looking crown is marked with three crosses. The personal 


46 BULLETIN 275, U. S. DEPARTMENT OF AGRICULTURE. 


factor may, of course, lead to misinterpretations unless the same 
standard is applied throughout the entire study. For this very 
reason it seemed doubtful from the beginning whether these data 
would be of much value. They are given here merely for the sake 
of completeness. 

The condensed material was again tabulated. In the condensed 
table (Table II) the relation of decay to age can easily be followed by 
comparing columns 2 and 6. ‘Decay rating” is placed between 
‘‘Suppression’’ and ‘‘ Wound rating” in order to bring out forcibly 
any possible relation between these factors. 


INTERPRETATION. 


The column that interests us most is apparently the sixth, ‘“ Decay 
rating.” In glancing over this column and comparing it with the 
neighboring ones we can read directly the connection of decay with 
factors that may be of influence. Each separate case of decay, of 
which one, two, or even more can occur on the same tree, may be 
called, for simplicity’s sake, in this study, a “cull case.”” Each cull 
case is the result of a separate infection. The actual loss of timber 
by fire burning out the stump does not concern us here; cull from 
this source is included in the ‘‘ volume of rot’’ whenever the decay 
is directly traceable to the fire wound. Otherwise the cull from fire 
isneglected. Cull from knots, limbs, or wind-shake is not considered. 
Altogether there are 97 cull cases. 

The first two cull cases are negligible for practical purposes. Some 
loss occurs in tree No. 125, 84 years old. We see that this is a very 
badly suppressed tree, very seriously wounded, in very bad health, 
and that it is injured by both fire and lightning. Another case occurs 
in tree No. 124, age 87 years. Again suppression, wounding, and 
condition of health are marked with three crosses, indicating the 
worst possible conditions, together with two causes of wounds—fire 
and lightning. In both cases fire is the more serious, lightning often 
occurring higher up on the tree in numerous small wounds. It 
carries advance decay to the upper part of the bole and materially 
increases the volume-rot figure and the decay rating. The next cull 
case is a slight one (tree No. 88, age 90 years). The tree is inter- 
mediate, wound rating medium, health good, the decay only advance 
rot. Continuing down the “Decay-rating’”’ column and comparing 
the symbols with those in the neighboring columns, we find that in 
almost every case the rating of rot more or less expresses or is ex- 
plained by the factors of suppression and wound rating. Apparent 
discrepancies generally find their explanation under ‘‘ Remarks”’ 
(column 10). 

Suppression shows at an early age. A distinct preponderance of 
suppression is noticeable from about the age of 84 years. The first 


FOREST PATHOLOGY IN FOREST REGULATION. 47 


_ very pronounced cases appear in the same year. They seem to be- 
come particularly common from about 110 to 120 years. 

Suppression stands out strongly as an important factor. Out of 
the total of 97 cull cases, 66 are connected with suppression. Consider- 
ing that our average volumes over ages were curved from figures 
which were rather low and that the intermediate white firs in a virgin 
uneven-aged mixed stand are rather to be considered as recovering 
suppressed trees than as dominants decreasing in rate of height growth 
the intermediate class may consistently be added to the suppressed, 
giving 73 in all, or about 75 per cent. Suppression is commonly con- 
nected with a more or less high.decay rating, provided the tree is 
wounded seriously. Again, low-volume trees with marked decay are 
more liable to be a total loss on account of their form. A rot volume 
percentage of 50, for instance, leaves still a good deal of merchantable 
stuff in a tree with high volume, but it would make a small tree com- 
pletely unmerchantable. In the comparatively few cases where 
dominant trees show decay, the wounding is either of very momentous 
character or the decay is more or less insignificant and localized near 
the scars. This is true at least for the younger trees. 

In glancing over the decay column we see that the higher ratings, 
xx and xxx, begin rather suddenly to become more frequent after the 
trees have reached the age of about 123 to 126 years; after the age of 
about 129 or 130 years they become very common. While decay 
in the broadest sense of the word may show in trees 60 years old and 
perhaps younger, the critical age of white fir with regard to more 
serious decay appears to lie at about 130 years, at least for the region 
investigated, taking into account that we have to deal here with a 
practically virgin stand grown up under the cumulative risk from 
suppression, frost, lightning, and the other factors of influence. 
Decay of any consequence appears at this age in trees with a combina- 
tion of wounding and suppression. In the few apparent exceptions 
the decay is localized near unusually large wounds. 

We find, further, that up to about 150 (148) years in badly wounded 
but dominant thrifty trees the decay is either not very far advanced 
in degree, if in extent, or that the wounding is of quite extraordinarily 
severe character. 

Tree No. 49, age 132, seems to form an exception, but we will see 
later that frost cracks, though not offering a large opening by virtue 
of their length, are instrumental in the longitudinal advance of the 
decay. It seems that after about 150 years thriftiness as expressed 
by dominance is less able to outbalance the influence of serious 
wounding. 

If it is at all permissible to draw any inference from the compara- 
tively small amount of material at hand, we may distinguish three 
critical stages in the life history of wounded white-fir trees, and we 


48 BULLETIN 275, U. S. DEPARTMENT OF AGRICULTURE. 


must remember that by far the greater number of our trees, especially 
after they have reached the age of about 80 to 90 years, are wounded. 

The first is the “age of infection,’’ which may be at 60 years or 
below. Here the infection rarely leads to more than negligible decay 
unless the tree is handicapped by quite unusually severe conditions, 
such as very large old wounds. 

The second, at about 130 years, which we may term the ‘critical 
age,” marks the point after which a combination of pronounced sup- 
pression and heavy wounding generally results in distinct decay. 
This combination of deleterious factors is one commonly found in 
virgin forests. Wounding alone is not sufficient to unfavorably 
counteract thriftiness of growth. 

Another change comes about at 150 years, when even dominant 
(that is, thrifty) trees become subject to extensive and intensive 
decay. Wemight term this the “‘age of decline,” because the inability 
of the individual to throw off or keep in check the growth of the wound 
parasite in its heartwood indicates a distinct decrease in resistive 
powers, whatever their specific action may be, induced by age. For 
thrifty but wounded white fir, such as we may expect to raise under 
management, the age of decline is, therefore, the factor which will 
influence the rotation and cutting cycles of the species, since for many 
years to come the risk of inoculation will be more or less the same. 
There will be fires as long as there are lightning storms. Wounding 
through lightning and frost are inevitable. Besides, many trees are 
already wounded. 

It is of interest to note that of a total of 160 trees only about 25 per 
cent did not show any wounds except very slight lightning scars. All 
the rest were wounded from some cause or other. - Often a combina- 
tion of fire, lightning, and frost cracks results in scarring a tree to such 
an extent that almost in every foot some blemish will be found. This 
is particularly true of the older trees which have been exposed to the 
cumulative risk of many years. Any of these wounds, if large enough, 
may offer an entrance to fungi. After the trees have reached the age 
of about 80 to 90 years, more than 70 per,cent of them are already 
more or less badly wounded and therefore exposed to inoculation. 
After they are about 106 years of age more than 80 per cent are 
wounded. 

In the remote future, when all these wounded trees are removed 
and when the risk of wounding for the trees growing up meantime is 
minimized, a new age of decline may be established. What this age 
of decline might be for unwounded white fir in managed forests we 
can not tell from our material, because of 97 cases of decay only 6 
were not to be traced to some wounding. It is obviously out of the 
question to take even a clue from data of so scanty a nature. It 
may simply be mentioned that the first case of this kind appears at 


FOREST PATHOLOGY IN FOREST REGULATION. 49 


an age of 134 years in a suppressed tree. After all, it may be more 
than a coincidence that the first case of such imfection in a sup- 
pressed tree occurs near the critical age for suppressed white firs in 
this region. It is within reason to assume that thrifty, uninjured 
white firs run only the evidently not very great risk of becoming 
infected through branch stubs. But decay entering through knots 
is always caused by fungi of a very aggressive character, such as 
Echinodontium tinctorium, which is not always the case with wounds. 
As a possible cause of infection we may also mention dead and broken- 
off leaders or volunteers, the stubs of which are only slowly overgrown. 

It would appear that, if infections of unwounded trees are really 
so rare, white fir will take care of itself on the managed areas of the 
future. This would probably be the case in an ideal, 100 per cent 
normal forest. But this is utopian. ‘There will always be a certain 
risk of wounding. Even after the already wounded individuals are 
eliminated, which will consume a number of decades, it is unreason- 
able to expect that our forests should then be so much closer to the 
normal than the best kept European forests are at the present day. 
How severe the loss from Trametes pimi is in the Prussian forests has 
already been shown. Whatever may be the final verdict as to the 
age of decline of unwounded thrifty trees in managed forests, it can 
not be of more than purely theoretical interest to us and the next 
following generations. We must cope with present-day conditions 
as we find them, not as we would wish to have them. 

The immense importance of firs in connection with decay appears 
so plainly from Table II that it is hardly necessary to emphasize the 
fact. The field notes show that in 59 trees wounded by fire, in only 
11 was no decay traced to the fire wound. Fire, then, is one of the 
most important factors in connection with decay; all the more so, 
as fire generally attacks the butt part of the tree, and decay starting 
from fire wounds therefore destroys a much greater part of valuable 
timber than decay in the upper part of the bole. 

Lightning generally results in comparatively light advance rot. 
From Table II it appears that the only tree in which serious decay 
could be traced to lightning, and in which it was neither connected 
with suppression nor with a serious wound from another source, is 
No. 59, 232 years old. To judge from our data, lightning is rarely 
connected with typical decay, although it often renders large parts 
of the tree partly unmerchantable. 

The cumulative risk of wounding is shown in Table IT (column 7) 
by the fact that the cases rated with three crosses become far more 
frequent after the trees have reached the age of about 90 to 100 years. 
After they have reached about that age such cases are commonly 
accompanied by decay. Serious decay follows serious wounding after 

98035°—Bull. 275—16——4 | 


50 BULLETIN 275, U. S. DEPARTMENT OF AGRICULTURE. 


about the age of 130 years (critical age) when combined with pro- 
nounced suppression, and without this it follows after the age of 
about 150 yearsisreached. The risk of wounding increases naturally 
with the age of the tree. 

A number of wounded and badly suppressed trees escape infection, 
although they are far beyond the critical age. Not every wound must 
necessarily be inoculated. All such cases found are compiled in 


- Table ITI. 


Taste III.—Data on suppressed and wounded but not infected white-fir trees. 


Suppres-| wound | Character of Suppres-| wound | Character of 
Age. iting) rating. wound. Age. rating’ rating. wound. 
a sax. x | Fire a xx x | Lightning. 
COLMA SSS Oe P.0.¢ D. ©. Do. BOM. 2 ces oe ee xxx x Do. 
1a RES pees 56 6.4 Do. 1 of? ae 6, eee axx = Do. 
1 ek 5 penile TO.o.4 x | Lightning. Was teu sete p.o.0.4 xx Do. 
ES a ee mex Roe Do. DO ei ale vee ee x ex Do 


In all cases but one in Table III the degree of suppression is very 
high; in this case the wound rating is low. The dangerous fire 
wounds in this table are confined to the youngest ages, 87 to 111 
years; they were comparatively small in each case. The rest of the 
wounds are all due to lightning, which, as will be remembered, does 
not open up the interior of the tree unless very large parts of the 
bark are killed. For inoculation and infection, the character of the 
wound is all important. Suppression has nothing to do with inocu- 
lation; only after infection has taken place does its influence make 
itself felt. 

The characteristics of each of the three ages, of course, hold good 
through the following ages. The combination of wounding with 
suppression, as shown in the critical age, for instance, must continue 
to favor decay in the age of decline. 

Relative thriftiness (apparent condition of the tree) seems to have 
the least influence on the decay factor. It is really nothing but a 
statement of the present temporary appearance of the individual 
tree, which may be entirely different from what it was a few years 
ago or what it will be in the near future. . 

That far-reaching decay must not necessarily be reflected in the 
appearance and increment of the tree is shown, for instance, by trees 
Nos. 25 (age 150), 157 (age 150), 85 (age 152), 83 (age 156), and 
others in Table If. In all the trees mentioned, Hchinodontwum 
tunctorvum had established itself and was vigorously growing. ‘Tree 
No. 85 (age 152) even had two sporophores, and more than half the 
volume of the tree was decayed, indicating that the fungus must have 
lived in the tree for many years. The tree was apparently very 
thrifty; its volume, 192.5 cubic feet, as against 101, the average for its 


FOREST PATHOLOGY IN FOREST REGULATION. 51 


age (152 years). The increment was good. We can not, therefore, 
make EHchinodontiwm tinctorium responsible for the decrease in 
thriftiness of infected white fir. 

In order to further fix the relation between the character of the 
opening through which the fungus gains entrance into the wood and 
the character and extent of the decay, all cull cases were tabulated 
separately (Table IV). 


TaBLE I[V.—Cull cases of white fir, showing the extent of typical rot and its relation to 
the wound through which the infection took place. 


Wounds. Typical rot. 
-_-—~‘No.} Age.| Infection traced to— In- | Confined Extend- Remarks. 
Oven, |, ternal i a ing much 
a (healed — beyond 
over). | outs wounds 
1 2 3 4 D 6 7 8 
136 60 ene Pees -. b= 2, - — z x -- Negligible. 
143 eo ee ee ee — Ke x — 
125 84 Fire with lightning. .-.. x — x — 
144 Bovee rest crack. ...........-. _ 3 pe — Negligible. 
124 87 ehining with fire..... x —_ D6 _ Advance rot. 
88 Re RE ee — p. x —~ 
122 on eae ee 21S GORE Beare ole x = x _ 
76a 2 a x — _ (Xx) 
foo |. 96-" Lightning: /-........... x at _ — Advance rot. 
ye oe es x — 4 — 
See Sees ee GOs... 2. ).\..-....- = x -- (x) Remained open 22 years. 
Ce SL ite — x 20 _ 
BO " x x = 
Roe eee ipaune. .- 2-25.22. — by x “= Almost completely girdled 82 
4 years ago; open 31 years. 
ee De — be — 
Bee ete edo... 39d. ...--2.. x - x _ 
aie) oe | Eaehining.-...-....-2.- x x x = Negligible. 
68 | 107 | Woundfrom falling tree.| x — D.¢ 
HOT ear himingirs Jol 2. 22S _ 5 x — 
As Ode rOSbiCracke ss: .).... 22. - Xs _ 5G — 
A Se ea x: — < ps 
c(t ae eT ED, oo. sei D — x mS 
TOS Pete Ok. CO Sethe aang ae x —_ x _ 
94 | 112 | Twin and frost crack...| — x a>. _ 
99") 112 || Pighinings.< 5... 2.2... — x x — 
37} 112) Frostcrack............- — x (?) _ Frost. 
ee a x — x _ 
pala Cy eae COREE EE. 2 Sea ae x _— Be a 
LOOMP FIG HESS. Oo 3 els aera 5% _ De = 
Bam Pass fyine (2)iioec.) -........ — x x — 
74D | 119 | Lightning.............- ae —_— % — 
58 | 123 | Frostcrack............- — x — x Frost. 
Gut a20 ) Lightning... ..-.-..22- — x ¥ — 
PED DRE oe RMEO yo atas onjs-<'s'~ = 45,005 5 - B _ P< — 
38 [Pearl eae 0 2 ae _ x x — 
Oy 424) Prostcrack............-. x — — _ Advance rot. 
113 | 124 | Fire withlightning..... < _ x _ 
41} 125 4 be, eB x — Xe — 
6090126 | Prost.crack.. =. 2-22...) — x — b. Frost. 
79 | 129 | Fire with frost crack... X _ — os Do. 
54 | 130 | Lightning... ....-......- — x x ~~ 
(ie! || WELD | Or: ee a ee Sa Xs — x — 
G5} (asl) Frosterack: . 4. ----.). _— x — D4 Frost. 
9 a8 Nia |  S DSR et SORE 4. eee ~ oe — x Do. 
Aone ass ME ITOLE Lessee cit (3. 5 x _— p< _— 
OR go eo ee — (@) x — 
Mies lf idaoun Kemots: fer! 42 2 fein. os — _ — x Knots. 
55 | 135 | Fire withfrostcrack....| — x — Be Frost. 
26 | 136] Frostcrack............- x _ _ x Do. 
ENS! | Ql) Cyl 6s 10) SS _— ~- aa pe Knots(?). 
50 | 137 iewines and knots....) — P< _ x Much advance rot. 
[TELL PLO 8 a Sn (?) — be Sporophore. 
70 | 140 Lightning We Ob eee ee x x -——~ 
pow 14Qu oe MORE a See x — Xe _ 


iy BULLETIN 275, U. S. DEPARTMENT OF AGRICULTURE, 


TaBLE IV.—Cull cases cf white fir, showing the extent of typical rot and its relation to 
the wound through which the infection took place—Continued. 


Wounds. Typical rot. 
No. | Age.}| Infection traced to— Tn- pecan Extend- Remarks. 
Open. | tem al | borh Nis q | ing much 
* |Chealed of beyond 
over). rote. wounds 
Lusi 3 4 5 6 7 ‘8 
155}. 140.) APabO acces eeeweeee ete = x — — x Condition very poor; sup- 
pression xxx. 
43 | 140]..... (6 0 Pam Bea) Ne x — x ——— 
ESO 3} Aa ee Gok... 2: eee eee x == pe — 
6la | 143 eget CISCK.i.c. tee ee cee — x — = Frost. 
61b | 143 Falling trees... eee —— x 2 — Advance rot. 
AY TACT IB cs oe nc. eee C7) (?) (?) (?) Notes incomplete. 
106 | 146 Lighting and frost..... x _ x — Advance rot. 
®: |, 148 | Wrosterack.....¢ -stepec — x — 2. Frost. 
O21) 149 | SINIPR Lo ae uses ack eee eee x — x — 
25 | 150 | Frosterack.........-... xe — — 2.6 Frost. 
114} 1505] PRaTO: Sac cee ss eeceee ee eee x — — Xi Butt open from fire 73 years 
ago; Suppression xxx. 
157 | 150) je... Gets ht oreo eee x — x —— 
Tole aor WAG etcuns Shite o> acieaee eeee — x x — 
85" | 152) | Brostierdek. 97 -e--- 2eee — D8 - x Frost. 
9 177) Oat pose ae eee — b x —- 
DS Loon ILS s ac eee epee sneer 2.4 — — x 
Dll LOD. tee. 4 Ot cei HE Eh cic acct x, — x —_ 
17] ToS | Lightning: 64.2.2... -- x 2 — 
S3al) 1564), Brosterack.o-.-cbnceee — + — x Frost. 
OTe MG PAPO sc csace See cet oecm ee x - x — 
GE em 3 ee On aeeeie Bie Pea x — _- x 
O35) 160 Oigereehs =). -- ore x ao — x Suppression xxx. 
160 |) Gl61)) Brosticrack:. 22. <b caviac.sj: x — o x Frost. : 
Slali6St Mise paciesect +. ce). Ce — — x Condition very poor; sup- 
pression x. 
S47) 1644) IeNOtses oe eee eee. <aoee — — as x Knots. 
Sill AGS dbreme ate epics .- on bons. x —_ — x 
SIM re IGS dacin - OOS TEEE «scl ass Hale — x —— x 
24+) 16G IPN eek phe. caabie aun (2?) (?) (?) (?) Notes incomplete. 
$2.) 169") Kot. .o2.- sci ope eee — —- - x Knot. 
Si A904 Wire sidbeicge 4 uo: owes (?) (?) — x 
bf.) 270,| Brosteracks..--f.2- sae -- es — x Frost 
67 el FOV) Keno tose area. aeons — — “= x Knot. 
649 | W755) Hire. cu: 2. ec ee weeks og _ — Xe Suppression xxx. 
64by| 175 | Waghtning ).ees-5sec-se. _ X x — 
Bo) AB a. AO oe ngcets oe oe eke — x 24 — Advance rot. 
if a sO Oe ee re eee ae x -- x — 
42 | 183) Raighimang..-.. 0... 22 _ x x — 
959] 185. |) Wire: 4% ..25. 4-228. seer x — xe Suppression xx. 
BO" etOL sees e rs (oan 25 = Se Se x — — x Dominance xxx; fire 110 
years ago; deep burn. 
86 | 192 | Frostcrack.....--...... — x — Xs Frost. 
14 92001}. 2232 OES Sete. Se nee — B. x _ 
142) 200.) BIO. 2. can cabuec eee x — -- x Condition very poor; sup- 
pression xxx. 
738 | 221 ) Frosterackss% 2.2.22. —~ x _ cs Frost. 
73b.| 221 | Lightning. .....5.2. 200° x — 2 — 
BOU| e252 dhe eee GOs desc act. cosets — pd — x 
141 | 258 | Fire with frost crack. ... x _ x - Advance rot. 


Table IV is designed to show whether and in which cases typical 
rot extends much beyond the wounds forming the entrance for the 
fungus. Column 7 is the one to be followed (‘Typical rot, extending 
much beyond wounds’’). The affirmative is expressed by a cross, x, 
the negative bya dash, —. Cases which are on the line between the 
two are marked by a cross in parentheses; they are negligible for 
our purposes. The first tree to be considered, No. 58, is 123 years 
old and has a frost crack. From this age, or rather after 126 to 130 


FOREST PATHOLOGY IN FOREST REGULATION. 58 


years, these cases become more and more frequent. In most cases, 
to judge from this table, frost cracks are a strong factor for extending 
typical decay much beyond the point of entrance of the fungus. By 
splitting the bole for a considerable length they allow air to enter the 
wood, which evidently stimulates the growth of the fungus. 

In noting the cases of decay traced to the wounds or openings 
through which the fungus found its entrance, it is seen that two and 
even more cases of decay (cull cases) may be found on the same tree, 
but each case is counted separately. Where decay is traced to a com- 
bimation of two factors, each factor is shown separately. The means 
of entrance of the fungus causing decay are thus shown to be as fol- 
lows: Fire, 48; frost, 25; hghtning, 23; other causes (including knots, 
girdling, etc.), 13; total, 109. 

These 109 wounds (including knots, etc.) led to 97 cull cases. Out 
of 109, only 13 were other than wounds from fire, frost, and lightning, 
and 11 of the 109 cases of decay were the effect of a combination of 
two of the causesnamed. Fire has by far the greater share; frost and 
lightning are second, but the preponderance of fire and frost over 
lightning is greater than would appear, since they are far more serious 
with respect to causing decay. If ratings are given, more or less. 
arbitrarily, but yet in keeping with our field observations, to the var- 
ious causes of wounds in the order of their importance with relation 
to damaging decay in white fir, taking injury from lightning (the 
least consequential) as the unit, we have: Fire, 3; frost, 4; lightning, 
1; other causes (including knots, girdling, etc.), 3. Then, multiply- 
ing the figures for means of entrance by these relative ratings we have: 
Fire, 144; frost, 100; lightning, 23; other causes, 39. These figures 
express the following facts: (1) Fire mjury isnot only numerically the 
strongest, but also commonly leads to considerable cull; (2) frost dam- 
age is less frequent (above all, less ubiquitous) than fire damage, 
because it appears only in typical frost belts or frost holes, but it car- 
ries decay over a much greater length of the bole; (3) lightning injury 
is fairly common, is also restricted to certain belts, and leads more 
often to superficial rot; (4) other factors are of importance as causes 
of damaging decay, but they are comparatively rare. 


CONCLUSIONS AND OUTLOOK. 


The interpretation of the results of this study of the white fir from 
a practical point of view can not leave out of consideration the fact 
that the basis for all computations and tables is a comparatively small 
one and that the actual figures and many of the principles derived 
therefrom have more the value of strong indications for local appli- 
cation than the force of generallaws. Still quite anumber of the con- 
siderations will be directly applicable, at least in all similar types, 
some throughout the range of white fir. The writer would emphasize 
again that the aim of the present study is not to lay down laws, but 


54 BULLETIN 275, U. S. DEPARTMENT OF AGRICULTURE. 


to show by means of one example the problems before us and the 
various steps leading up to a working method for the future estab- 
lishment of laws which may—or may not—confirm the conclusions 
from this study, and to strongly advocate similar studies on a larger 
scale. With this point plainly in view, but assuming that our con- 
clusions are a step in the right direction, we may discuss thea bear- 
ing on the silvicultural problems that are before us. 


DECAY IN RELATION TO WOUNDS. 


In most cases, decay in white fir is caused by Echinodontium tinc- 
torvum. The mycelium never enters through the intact bark. Fire 
wounds offer the most common way of entrance; hence, in the major- | 
ity of cases, decay starts in the butt; frost is less common than fire, 
but favors the vertical spreading of typical decay. Localized and 
superficial advance rot, frequently leaving enough merchantable 
timber in the log to make it worth while handling except when 
occurring in the upper part of the bole, is often connected with lght- 
ning. Other means of entrance, such as knots, wounds from falling 
trees, and girdling by rodents are comparatively rare. 

These factors group themselves naturally into such as are uncon- 
trollable and such as may be controlled directly or indirectly. The en- 
trance of decay through knots, wounds from trees and limbs thrown 
in heavy storms, or from excessive snowfall lies beyond our control. 
Injury from mammals as a starting point of decay is very rare and 
will become even more so with the decrease of the forest fauna. 

The other factors are more or less open to influence. Fire is dis- 
tinctly a directly controllable factor. Lightning and frost are, of 
course, not directly controllable. Itis a fact, however, that both do 
not occur to any damaging extent except in more or less well-defined 
belts, and generally more heavily in foci inside of these belts. The 
natural inference would be not to favor white fir in such belts when 
possible. As a first step in this direction the establishment and map- 
ping of frost belts, frost holes, lightning zones, and lightning foci 
would be of particular value, which should not be confined to white 
fir alone. Other forest trees are also more or less subject to injury 
from both factors. The value of such maps should also make itself 
felt in forest-fire control, for the proper distribution of protective 
forces and improvements. 


FOREST REGULATION. 
CARE OF VIRGIN FORESTS. 

It has been heretofore pointed out that practically the only means 

of silviculturally influencing the national forests on a larger scale at 


the disposal of the administration at the present time lies in the han- 
dling of timber-sales areas. On all the vast forests outside of these 


ae 


-_——— 


_ 


| 
: 
: 
} 
| 
: 


FOREST PATHOLOGY IN FOREST REGULATION. 55 


comparatively restricted areas the same beneficial and injurious con- 
ditions must continue to prevail, which on one hand govern the annual 
increment and on the other make for annual total loss. Only one 
single component of the total-loss factor, though a most important 
one, may be controlled to a certain degree directly. Forest fires are 
in ever-increasing ratio eliminated from the national forests and, 
therewith, also the danger of trees being fire scarred and opened to 
the attacks of heartwood-destroying fungi. But the best of fire pro- 
tection can not restore to their original state of intactness the over- 
whelmingly large number of older trees which have been opened by 
previous fires. The open fire wounds continue to offer an easy 
entrance to fungi. It is true that fire protection prevents small 
wounds from becoming larger and keeps healing wounds from being 
opened again by repeated fires. The sooner such fire-wounded trees, 
as well as all other undesirable individuals, including all badly 
injured, diseased, and misshapen ones, can be eliminated from the 
forest, the better. There is little hope, however, for this to be done 
outside of timber sales. Adequate fire protection, both of water- 
sheds and of commercial timber, must of necessity be paramount to 
silvicultural work of this kind. 

Practically virgin forests may also be influenced by sowing and 
planting. This is done on so small a scale, compared to the total of 
existing forests, that we can hardly speak of any real silvicultural 
change. Knowing, however, that white fir can not be expected to 
yield full returns in belts subject to lightning and severe frosts, the 
forester should avoid favoring white fir in such localities. 


FOREST REGULATION THROUGH TIMBER SALES. 


Cutting timber does not in itself constitute sound silviculture. It 
may lead to regulation, or it may spell ruin to the forest. 

The administration of the national forests is not able to have 
timber cut by selling it where cutting is most needed. Accessibility, 
local demand, and last, not least, the quality and condition of the 
timber are stronger factors in finally locating a timber-sales area 
than silvicultural needs. A strong admixture of inferior species in 
itself is often sufficient to let an otherwise attractive sale fall through. 
Here, the prejudice of the purchaser against such species as white fir 
and incense cedar is responsible for forcing the Forest Service to leave 
an area badly in need of improvement in its virgin state, with all the 
cumulative risk to which it is exposed. The prejudice against white 
fir is widely established and not always confined to the lumberman. 

From a silvical point of view the. prejudice is directed against its 
very aggressiveness, which tends to give the species an ascendency 
over the more valuable but less tolerant pines. But the disfavor in 
which it is held by the forester is really nothing but a reflection of 


56 BULLETIN 275, U. S. DEPARTMENT OF AGRICULTURE, 


the strong objection made by the purchasing lumberman to accepting 
white fir in Government timber sales, and this is based mainly upon 
the unsoundness of the timber. At the same time, there is a fair local 
demand for sound white fir for a number of uses. There is no valid 
objection to clear and sound white fir. In fact, many a purchaser 
would rather pay higher stumpage for white fir if he were allowed to 
take only sound young stuff, which is in demand for dimension stuff 
(2 by 4, 4 by 4, etc.), for frame stuff, timbers, and stickers, and for 
butter boxes, etc. Purchasers complain that much of the material, 
though seemingly sound, ‘‘has no life’ after going through the mill; 
it becomes brittle and falls to pieces when dry. Sound white fir 
neither becomes brittle nor does it fall to pieces. It is the unsound 
material (advance rot) only which is objectionable. The remedy is 
easily seen; it consists in liberal and judicious scaling, which would 
rather give the purchaser the benefit of the doubt. The scaler will 
find valuable aid in the occurrence of decayed knots on the boles of 
trees affected with strmgy brown-rot. To the casual observer they 
may appear normal; when they are knocked off with a hatchet or 
similar instrument the decayed rusty interior is exposed. These “rusty 
knots” afford, in the vast majority of cases, a valuable indication 
of more or less far-gone Echinodontium rot in the heartwood of white 
fir. Occasionally, the rusty color is missing, but the center of the 
knot is unmistakably decayed. The verdict as to the rottenness of 
the heartwood will be the same. The knots are often very small. 
When sound, they are very brittle and glassy in appearance. To 
give a practical example: 

No. 82 on the Otter & Burns tract, a very fine tree with a long clear — 
bole, 29.4 inches diameter breast high, and 154 feet high, had been 
given a full scale. The bole had been bucked into 16-foot logs. To 
the scaler there were no indications of decay. After examining the 
tree the writer threw out log 5. The only indication for spotting 
Echinodontium decay in this log was‘the presence of the rusty knot. 
The log was opened and found to be unmerchantable from 0.5 to 
5.6 feet from the lower end, leaving as merchantable 0.5 foot on one 
end (diameter 19.5 inches) and about 10 feet on the other end (upper 
diameter 16.3 inches). Had the defect been known to the bucking 
crew a more advantageous dividing up of the bole in log lengths to 
the exclusion of the decay would have meant a saving to the operator. 

Among others, Bryant! has pointed out the necessity of more judi- 
cious bucking and of closer utilization. 


1Bryant, R.C. Waste in cutting timber. Jn Amer. Forest., v. 19, no. 11, pp. 790-799, 7 figs., 1913. 


FOREST PATHOLOGY IN FOREST REGULATION, 57 
MARKING, 


The entire silvicultural results obtainable by way of timber sales 
are directly dependent upon proper marking, the importance of 
which can not be overemphasized. Marking is by far the most 
portentous of all silvicultural activities and requires a very specific 
training, of which a complete knowledge of all components of the 
total-loss factor must be a prominent part. 

Marking in the selection forest has a threefoid object—to select 
trees to be cut and utilized at once, to leave others as a basis for 
future cuttings, and to establish desirable reproduction. Here. the 
interests of the Government as timber owner and timber producer 
frequently conflict with those of the purchaser. The purchaser can 
not be expected to take a strong interest in the future of the area he 
is to cut over. He quite naturally wants as much sound merchant- 
able timber from a given stand as possible. The larger the amount 
of timber he can cut from an area the smaller the overhead charges 
will be per thousand feet, board measure. In offering white fir for 
sale it is, therefore, important to be able to estimate more or less 
correctly the amount of sound timber on a given tract. If our 
figures prove correct, the loss factor in white-fir trees will be com- 
paratively small up to an age of about 130 years; after trees with a 
combination of wounding and suppression have reached the age of 
130 years they are liable to contain decay; after they have reached 
the age of 150 years wounding elone, even in dominant trees, is 
lable to lead to damaging decay. That trees with sporophores are 
decayed, at least partly, is self-evident. The actual cull per cent 
from decay is at present only guessed at. It is the constant aim of 
forest pathology to reduce this guesswork to actual and concrete 
figures. It is intended to repeat similar studies throughout the 
range of white fir and later also on other species in the order of 
their importance and finally to establish broad zones of equal path- 
ological conditions, in which the rot percentage may be given in 
definite figures. 

Marking can only be done correctly if the outcome of the marking 
with regard to the trees left standing is constantly kept in mind. In 
our specific case, for instance, white fir on typical lightning and frost 
belts should be marked very heavily. We know that here the loss 
from decay, particularly following frost cracks, is heavy and will grow 
through cumulative risk. White firs with serious wounds, especially 
with partly open fire wounds, must be marked heavily to as low a 
diameter as practicable. 

On the other hand, thrifty unwounded trees, where desirable, may 
be left without much risk up to the age of about 150 years, and prob- 
ably much longer. 


58 BULLETIN 275, U. S. DEPARTMENT OF AGRICULTURE, 


The effect of logging on the pathological condition of white firs that 
are left on the area may be twofold. The opening of the crowncover 
through cutting will prove beneficial to all suppressed and interme- 
diate white firs. The ready response of the species to light is well 
known. It is probable that such trees, if already infected, will not 
allow the decay to proceed very much farther, i. e., the newly formed 
upper logs may be sound. These trees move up into the dominant 
class. The mycelium in the heartwood, however, if well established, 
will not die out, and after a while sporophores appear which carry the 
disease to hitherto sound trees. As there can not be any infection 
except through spores coming from sporophores on diseased trees, it is 
evident that it is poor silviculture to leave individuals infected with 
any parasite of economic importance on cut-over areas. Such trees 
on timber-sale areas should be marked and cut under all circum- 
stances if we expect to save and utilize the sound timber they may 
contain and to protect other trees from decay. Sanitation of the 
forest must be the first and fundamental step in forest regulation. The 
introduction of the so-called sanitation clause in the timber-sale con- 
tracts of the Forest Service aims at this very point. 

It is evident that blind enforcement of the sanitation clause, 
following the letter and not the spirit of the principle expressed, is just 
as pernicious as laxity in its application. Not all parasites are of 
equal importance; our efforts should first be concentrated on the most 
dangerous ones. The time will come when forest sanitation will 
include all controllable elements making for loss in timber volume and 
timber values. 

On the other hand, if only thrifty trees are left standing after log- 
ging operations, they are, by the very opening of the “forest screen,” 
more exposed to flying spores from surrounding untreated tracts, but 
unless wounded they are in no great danger of infection. The smaller 
the tract, the more will this influence make itself felt. The improved 
conditions under which they grow will help them to either overcome 
or limit the extent of decay in case they do become infected. As long 
as we do not possess any exact figures on the recovery of white fir on 
cut-over areas, however, it is advisable to consider wounded white-fir 
trees left standing as unaffected by the opening up of the stand, at 
least during the transition period, that is, in first fellings. All these 
trees have grown up under unfavorable conditions, and the chances 
that they are lastingly injured are considerable. By the time second 
logging operations cover the area, it is to be assumed that a more pro- 
found knowledge of the life history of white fir will be at hand. 

The choice of white-fir trees to be left on the area, with the expecta- . 
tion that they will be sound and merchantable at the next felling, 
depends altogether on their condition and the length of time probably 
elapsing until that felling takes place. Assuming that our figures 


OE EE 


FOREST PATHOLOGY IN FOREST REGULATION. 59 


are correct and that the next cutting may occur, for example, in 30 
years, we may with comparatively small risk leave thrifty unwounded 
trees of any age on the area; wounded but thrifty trees of more than 
120 years are to be cut, wherever practicable, because in 30 years 
they will be over 150 years old, at which age trees of this class are 
more liable to deteriorate. Wounded trees which at the same time 
are suppressed should be eliminated. It is bad silviculture to leave 
individuals in the forest which not only do not produce the maximum 
of timber but which in all probability will prove a total loss and which 
occupy the place that should be fully stocked with trees promising 
a full and sound crop. In case of an emergency, such as occurs 
under very unfavorable market conditions or where the protection 
of young stuff is the most important feature, wounded and sup- 
pressed white firs left standing should not be older than 100 years, 
since in 30 years they will have reached their critical age—that is, 
130 years. After they have reached this age it appears that dam- 
aging decay becomes prevalent in trees of this description. Very 
severely injured trees have, of course, no place in the managed 
forest. The same is true for unusually suppressed or unhealthy 
trees, unless it may be expected with reasonable certainty that the 
opening of the crown cover will benefit them materially. Trees with 
open fire scars and with open frost cracks should be cut in preference 
to those with lightning scars or those having wounds from falling 
neighbors. In short, all wounds reaching far into the wood are to 
be given a higher rating with respect to decay than superficial wounds 
unless the latter are unusually large. 


PATHOLOGICAL ROTATION AND CUTTING CYCLES. 


Since we may expect that cutting during the period of transition 
will practically eliminate all those trees which by their combination 
of suppression and wounding become subject to early decay (critical 
age), the age of decline forms the basis for what might be termed the 
‘“nathological rotation,” for want of a better expression. It does 
not indicate that a given species should most advantageously be cut 
in regular intervals expressed by the pathological-rotation age, but 
that it should not be cut at a higher age. It is really a factor limiting 
the rotation and therefore also the cutting cycle. 

Rotation based on maximum volume alone can not be more than 
a makeshift during the transition period; logically it should be nar- 
rowed down to maximum-volume production of sound timber. Such 
species as Sequoia gigantea and Sequoia sempervirens are so resistant 
to decay that their pathology will not influence their rotation at all. 
In some of our valuable pines the pathological rotation will probably 
be very high, either coinciding with or reaching beyond the age of 
maximum-yvolume production. In white fir, incense cedar, and a 


60 BULLETIN 275, U. S. DEPARTMENT OF AGRICULTURE, 


number of other so-called inferior species, the pathological-rotation 
age is presumably lower than the age of maximum-volume pro- 
duction. We must look to forest mensuration for final data to settle 
this point. } 

Barrington Moore ‘ advocates a rotation based on the “period dur- 
ing which the rate of volume production is greatest or shortly after 
it, provided it is long enough to give the most valuable product.’”? 
Here, again, the pathological rotation will be the limiting factor, 
except for species in which the rate of greatest volume production 
possibly occurs at a lower age than the pathological rotation. That 
the value of lumber grades is bound to play a far more important 
réle in the future than at present, with regard to rotation, is a fore- 
gone conclusion. 

So far, we have considered only the rotation per species. In pure 
or almost pure stands the rotation of the unit is determined by the 
rotation of the species clearly dominating, not only numerically, but 
also in value. 

As soon as two or more equally valuable commercial species appear 
together in about the same proportion, the rotation of the stand 
becomes “‘synthetic;’”’ that is, the rotation for the unit is governed 
by the individual rotations per species. In the great majority of 
cases neither the representation of the species nor their individual 
values are the same. Nearly always there will be certain species 
more desirable than others, which latter then are classed as more or 
less inferior. A weak representation of inferior species with low 
pathological rotation will be without much effect upon the synthetic 
rotation of the unit. The stronger the representation of inferior 
species, the heavier will be their bearing on the synthetic rotation. 

On many of the large private holdings of the West the inferior 
species are disregarded altogether; they are simply left standing in 
logging operations. Unless the logged-over area is burned, the 
representation of inferior species is then an unduly heavy one. They 
must necessarily dominate the stand in the future. 

The national forests, on the other hand, will be the regulated for- 
ests of the future. In many of the national forests, particularly in 
the West, several species of unequal value are represented on the 
same unit in such a manner as to make each one a strong factor to be 
considered. Here, regulation of yield must be based upon synthetic 
rotation and synthetic cutting cycles. Rotation and cutting cycles 
for each species must be determined separately, each on the chosen 
basis of either maximum-volume production, or rate of maximum- 
volume production, or production of maximum value, limited in 
Plumas National Forest, district 5. Appendix (continued), Silviculture. (Unpublished. Furnished by 


courtesy of the U.S. Forest Service.) 
2See also Zon, Raphael, Balsam fir, U.S. Dept. Agr., Bul. 55, 68 pp., 2 pls., 8 figs., 1914. (See p. 67.) 


FOREST PATHOLOGY IN FOREST REGULATION. 61 


every case by the age of decline. The synthetic rotation is figured 
on the basis of the specific rotations, under due consideration of rep- 
resentation and relative value of each species from a commercial and 
silvical point of view. The same is true for cutting cycles. It should 
not prove impossible to express both representation and _ relative 
value for each species in symbols, which, together with the specific 
rotation, would permit the balancing of each species against the 
others, and thus to arrive at the synthetic rotation of the entire unit. 
In this way the inferior species will be given their proper place in for- 
est regulation. This procedure is undoubtedly followed more or less 
consciously wherever regulation is planned by way of timber sales. 
It can not be reduced to a practical working system, however, until 
all factors upon which it is based are thoroughly known. 

The pathological rotation limits the rotation of white fir, on the 
basis of our present knowledge, to 150 years—at least during the 
transition period. Perhaps the actual felling age for the species will 
be shortened long before that time arrives. The chances of pro- 
viding for the next decades are distinctly better. On areas cut over 
to-day we may expect second operations in not too remote a future, 
taking the place of a second improvement felling. Provided our figures 
prove correct, the critical age and the age of decline will be a safe 
guide in tentatively fixing cutting cycles for white fir, which, together 
with the cutting cycles for the other species present, will permit the 
establishment of the synthetic cutting cycle for the unit. 

Our present knowledge of the pethology of white fir leads us to the 
following practical conclusions for the period of transition: 

Prejudice against white fir as an inferior species. 

Conservative scaling (excluding advance roi) in favor of the purchaser on the one 
hand and of better utilization of sound white fir (where market conditions 
permit) on the other will in time overcome the prejudice. 

Silvicultural treatment of white fir. 

Reproduction: Frost and lightning zones are to be avoided. 

Marking on timber sales: 

On frost and lightning zones marking should be heavy. 

Badly wounded trees, particularly those with open fire scars or frost. cracks, 
should be marked heavily. 

Badly suppressed trees should be marked heavily. 

Trees with a combination of wounds and suppression can not be figured on 
to remain fairly sound beyond the critical age of about 130 years. The age 
of such trees, if left standing, added to the number of years to elapse before 
the presumable next cutting takes place, must not exceed 130 years. 

Trees wounded, though thrifty, can not be counted on to remain sound 
beyond the age of decline of about 150 years. The age of such trees, if left 
standing, added to the number of years to elapse before the presumable 
next cutting takes place, must not exceed 150 years. 

Rotation and cutting cycles. 

The rotation for white fir, as far as we can judge now, can not exceed 150 


years. 
Cutting cycles for white fir must be limited by the age of decline. 


62 BULLETIN 275, U. S. DEPARTMENT OF AGRICULTURE. 
OUTLOOK. 


The weak point in the example (white fir) discussed in this paper 
lies in the fact that the numerical basis of trees examined is insuffi- 
cient. Besides, what may be true for one set of conditions may 
prove wrong in another. Extensive additional studies on white fir 
in different regions of its range have been carried out during 1913. 

What has been done for white fir must be done for the other species 
as well. Investigations on incense cedar have yielded suggestive 
results; others are to follow. But not before all important species, 
from the lowest. to the most valuable, have been studied carefully 
with regard to their pathology can we expect to definitely figure the 
total-loss factor for any unit. To-day we are standing at the very 
beginning. ach species has its specific fungi, either one (as in the 
case of incense cedar), or practically one (as in the case of white fir), 
or several (as in the case of Douglas fir, sugar pine, and yellow pine). 
The relative importance of each of these fungi, their relation to 
influencing factors, their prevalence throughout the range of their 
- hosts, and, finally, the establishment of the critical age and age of 
decline from a pathological point of view, are still to be worked out. 
To this we must add the study of all the other components of the 
total-loss factor. 

The amount of work left to be done is enormous and will require 
many years. Concentration on the inferior species will yield results 
in a shorter time, enabling us to establish general rules to guide us in 
the transition period without causing too much damage to the 
interests of future generations. 


PUBLICATIONS OF THE U. S. DEPARTMENT OF AGRICULTURE RELATING 
TO DISEASES OF TREES. 


AVAILABLE FOR FREE DISTRIBUTION. 


Death of Chestnuts and Oaks Due to Armillaria Mellea. (Department Bulletin 89.) 

Disease of Pines Caused by Cronartium Pyriforme. (Department Bulletin 247.) 

Larch Mistletoe: Some Economic Considerations of Its Injurious Effects. (Depart- 
ment Bulletin 317.) 

Miscellaneous Forest Tree Diseases Common in California and Nevada. (Forestry 
Miscellaneous. ) 


e 


FOR SALE BY THE SUPERINTENDENT OF DOCUMENTS. 


The Present Status of the Chestnut Bark Disease. (Bureau of Plant Industry 
Bulletin 141, pt. 5.) Price, 5 cents. 

Diseases of Deciduous Forest Trees. (Bureau of Plant Industry Bulletin 149.) 
Price, 15 cents. 

Mistletoe Pest in the Southwest. (Bureau of Plant Industry Bulletin 166.) Price, 
10 cents. 

Timber Rot Caused by Lenzites Sepiaria. (Bureau of Plant Industry Bulletin 214.) 
Price, 10 cents. 

Diseases of Ornamental Trees. (Separate 463, from Yearbook 1907.) Price, 5 cents. 

Chestnut Bark Disease. (Separate 598, from Yearbook 1912.) _ Price, 5 cents. 

Practical Tree Surgery. (Separate 622, from Yearbook 1913.) Price, 5 cents. 


63 


: \ I ae a7) ih al ws rat 
eae : Pot eh 6 at N f i 2 
nl Sh 4 aah ‘ s, 


heh ine : 
; ara ‘Ns 
ols me AGE a OS ee 
PF AAyhow naw i oad) a 
¥ } 7 A108 Des) ; 
eh (rh * (>a r) ie ih 
d Oa ii 
hic 4 tage mA can 
) . i) u i ‘ie Ye 
} Rh ai 8 iy q ri f 
‘ *% t q P 
Ra POE a he 
LTULA Da i 
> ig? ay 
z Pate 
. ‘ J | arr 


ew. nF 


TAO So ST! GAY OEE 


ak ua oe ' , Toy aye win : 
Cute! OR CRT Oy 


4 i & 


_ 
ta 
aed 

pd 
~ 
se 
> 
r 
~ 
r 
~ 


0% TE DONO MA Be ERCgURES Ei 
‘THE SUPERINTENDENT OF DOCUMENT: 


GOVERNMENT PRINTING OFFICE 
WASHINGTON,D.C. 

> aa 

|) 10CENTS PER COPY, 


ie 


Vl Biot ae 

ete Me 

= ln DLO 

ay ia i sae he Atnom ult 


7 rT oil } 
: + i} at j 
i 
ime 
J et , wey , 
. n 
ae p 
La 
; 
. 
, 


OO 


UNITED STATES DEPARTMENT OF AGRICULTURE 


Contribution from the Bureau of Plant Industry 
WM. A. TAYLOR, Chief 


Washington, D.C. PROFESSIONAL PAPER January 15, 1917 


ENDOTHIA PARASITICA AND RELATED SPECIES. 


By C. L. SHEAR, Pathologist, and NEIL EH. STEVENS,’ Pathologist, Fruit-Disease 
Investigations, and Rusy J. T1LuEr, Scientific Assistant, Office of Investiga- 
tions in Forest Pathology. 


CONTENTS. 
Page. Page. 
a ee 1 | Physiology—Continued. 
PP eOMUIOME 25 s25-5 -.- 2225) 's2s25- + 1 Distribution of the species of Endothia.. 48 
Dae genus Hndothia.........-..-.25-.--- 3 Discovery of Endothia parasitica in 
‘ee cpecies oF Endothia-...--.....---..- 13 Sa ord cies es tn ore «ate ere ne stele 54 
Morphology and development. .........-.-.-. 22 Discovery of Endothia parasiticain Japan 58 
a 22 Present distribution of Endothia para- 
eo eee ee 23 Sitic¢a MNRAMIOLICA. 225-2. see ae oes cere 59 
Spore measurements..............-.----- 30 Host relations of the species of Endothia . 59 
ce BO. f MSPS BEN & yo Pisano ide a lois wee ees 74 
RreERPStUGIOS... 2... 2-2-0 ------------ 3 Titer a Gre CHOC a2 ooo vane weldnwiee oe =F ben's car 77 


TAXONOMY. 


INTRODUCTION. 


The discovery of a serious canker of the chestnut in the New York 
Zoological Park in 1904, by Merkel (49),? first attracted the atten- 


tion of pathologists and foresters to what has proved to be one of 


the most serious epidemics of a plant disease ever known in this 
country. 

The fungus which was found associated with these cankers (PI. 
I and Pl. II, fig. 1) and soon demonstrated experimentally to be 
their cause was described by Murrill (57) in 1906 as a new species 
of Diaporthe (D. parasitica). Search for the fungus in other places 
in New York and vicinity soon showed that it was already estab- 
lished and apparently rapidly spreading. Investigations which 
have been continued and extended from year to year have shown 

1 Formerly Pathologist, Office of Investigations in Forest Pathology. 

2 Serial numbers in parentheses refer to ‘“ Literature cited,’ at the end of the bulletin. 


Nore.—This bulletin is of value to botanists, especially plant pathologists and mycolo- 
gists, and to all persons who are interested in the study of chestnut blight. 


-43737°—Bull. 380—17 1 


2 BULLETIN 380, U. S. DEPARTMENT OF AGRICULTURE. 


conclusively that the disease is spreading very rapidly, especially 
west and south from New York and also north and east. 

The exact identity and relationships of the fungus causing the 
disease and the origin of the epidemic soon became the subject of 
study by various mycologists and pathologists. Different explana- 
tions were offered for the sudden appearance and behavior of the 
disease, one view being that the fungus was probably a foreign 
parasite which had been introduced; another, that the organism was 
probably a native species which had recently attracted attention, 
chiefly by reason of the weakened condition of the chestnut trees 
due to abnormal climatic or other conditions. 

In attacking the problem of the origin of the parasite and its pos- 
sible control, it was evidently necessary to secure all the information 
possible in regard to its life history, identity, distribution, and re- 
lationships. The senior writer in an unpublished paper prepared in 
1908 pointed out the close relationship and possible identity of 
Diaporthe parasitica with certain species of Endothia. Clinton (16) 
and Farlow (28) soon after also made the same suggestion. Two 
species of Endothia had already been described from this country 
by Schweinitz (74) under the old generic name, Sphaeria. These, 
however, had in recent years been regarded as a single species and 
referred to Endothia gyrosa (Schw.). Owing to a lack of knowledge 
of the types of these two species and for want of good specimens 
showing ascospores, it was difficult to determine what species of 
Endothia were indigenous in the eastern United States. Since it 
had been suggested that Diaporthe parasitica was either identical 
with one of Schweinitz’s species or a mere variety of it, the present 
writers undertook a thorough study of the genus Endothia in its taxo- 
nomic, ecological, and pathological relations. It was first necessary 
to determine the identity of the two species already described by 
Schweinitz from America and also to learn their distribution and 
host relations. As one or both of Schweinitz’s species were reported 
to occur in southern Europe on chestnut, it was important to obtain 
exact knowledge in regard to the identity and relationships of the 
European species. The senior writer spent several months in Eu- 
rope collecting material of Endothia in the field and studying her- 
barium specimens of types and authentic collections of Schweinitz 
and other authors. Material was also acquired by collection and 
exchange with pathologists and mycologists in nearly every region 
of the world in which Endothia was known to occur. Comparative 
cultural studies were made of all the living material secured, as well 
as inoculation experiments on various hosts. The recent discovery of 
the typical chestnut-blight parasite, Hndothia parasitica, by Meyer 
(27, 76, 78), in China and Japan and the failure to find in Europe or 
America any native form which would produce the disease appear 
to settle beyond question its foreign origin. 


ENDOTHIA PARASITICA AND RELATED SPECIES. ne 


The present paper presents the results of several years’ field and 
laboratory study of the species of Endothia. This includes the study 
of practically all the herbarium material of this genus preserved in 
the principal herbaria of Europe and America; also field and lab- 
oratory studies of over 600 new collections Pam various localities 
and hosts in America, Europe, and Asia. Over 4,000 cultures have 
been studied and about the same number of icin ond made. 
These studies include the systematic relations of the species of 
Endothia and their physiological behavior on various culture media 
and under various conditions of light, moisture, and temperature; 
also inoculation experiments with the various species on various hosts. 

The writers wish to record here their grateful. acknowledgment 
and thanks for opportunities to examine specimens and for assistance 
rendered by various mycologists and pathologists and directors and 
curators of botanical gardens and museums, especially the following: 
Prof. O. Comes, Naples; Prof. Romualdo Pirotta, Prof. Giuseppi 
Cuboni, and Drs. E. Pantanelli and L. Petri, Rome; Prof. P. Bac- 
carini, Florence; Prof. P. A. Saccardo, Padua; Dr. G. Briosi, Pavia; 
Dr. J. Briquet, Delessert Herbarium, Geneva; M. G. Beauverd, 
Boissier Herbarium, Geneva; Prof. L. Jost, Strasburg; Prof. W. 
Pfeffer, Leipzig; Dr. G. Lindau, Berlin; Dr. J. W. C. Goethart, 
Leiden; Prof. H. O. Juel, Upsala; Dr. P. Hariot, Paris; Sir David 
Prain, Kew; Dr. A. B. Rendle, British Museum; Prof. I. B. Balfour, 
Edinburgh; Prof. T. Petch, Peredeniya, Ceylon; Dr. C. Spegazzini, 
La Plata, Argentina; Dr. W. G. Farlow, Harvard University; Dr. 
W. A. Murrill, New York Botanical Garden; Mr. Stewardson Brown, 
Philadelphia Academy of Science; Dr. G. T. Moore, St. Louis 
Botanical Garden; Prof. E. Bethel, Denver, and Drs. G. P. Clinton, 
P. J. Anderson, and F. D. Heald. The writers have also received 
specimens and cultures from numerous other colleagues plage have 
been of great assistance and are duly appreciated. 


THE GENUS ENDOTHIA. 


The genus Endothia was established by Elias Fries in 1849 (33, 
pp. 385-386), as follows: 


(X. - Endothia. Fr.*) 


*Colore rubro fulvove, habitu Tuberculariae, peritheciis cellulosis difformi- 
bus pallidis, ascis diffluentibus, facile distinctum genus, nobis exoticum, sed 
jam in Huropa australi obvium v. ¢c. Sph. gyrosa Schw.—et subgenus, tuber- 
culo uniloculari, sistit S. Tubercularia Dec. Omnium horum generum char- 
acteres proxime plenius exhibeamus, examinatis multis speciebus exoticis. 


The description of the genus transcribed here was published as 
a footnote in the work cited and was evidently based on the specimens 
contained in Fries’s herbarium at the time the book was written. 


> 


4 BULLETIN 380, U. 8S. DEPARTMENT OF AGRICULTURE. 


Fries (31, p. 73) had at that time, according to his own statement, 
authentic specimens of Sphaeria gyrosa sent him by Schweinitz and 
also the specimens collected by Guepin and Levieux in France, 
which he identified as this species. In Fries’s herbarium at Upsala 
at present are found specimens of true S. gyrosa Schw. with 
Schweinitz’s autograph label, but no specimens of S. gyrosa could 
be found attributed to Guepin or Levieux. There is a small packet 
marked “Sph. gyrosa,’ apparently in Fries’s handwriting, but 
there seems to have been some confusion in the labeling or mounting 
of this specimen, as a small stroma of Zypoxylon annulatuwm which: 
does not look at all like Endothia is included. The other piece © 
consists of an irregular pycnidial stroma which may be the southern 
Kuropean specimens referred to in the description quoted. Fries’s 
identification of this European material as FZ’. gyrosa was apparently 
based chiefly upon its superficial resemblance to the pyenidial 
stromata of Schweinitz’s American specimens. The senior writer has 
seen and made a careful microscopic examination of a specimen col- 
lected by Guepin in France and preserved in De Notaris’s herbarium 
at Rome. It is labeled “ Sphaeria gyrosa Fries, Guepin, Angers.” 
The specific name “ gyrosa” has been crossed out by De Notaris 
and “radicalis Schw.” written above it and the date “ April, 1845,” 
added. This appears to be a part of the same collection that 
Guepin sent to Fries, as the specimen agrees well with Fries’s 
description and consists chiefly of pycnidial stromata which are 
rather larger than is usual for Sphaeria radicalis and show con- 
siderable superficial resemblance to the stromata of Sphaeria gyrosa 
Schw. A thorough examination of this specimen, however, reveals 
a few perithecia and ascospores, which leave no doubt that it is 
S. radicalis of Schweinitz, as indicated by De Notaris on the label. 
What the plant sent Fries by Levieux was is unknown, as no speci- 
men so labeled could be found in Fries’s herbarium. It appears 
from all the evidence at hand that Fries was mistaken in his identi- 
fication of the material from Levieux and Guepin, as no specimens 
of the true Sphaeria gyrosa Schw. have yet been seen from Europe. 

There seems to be no doubt, however, that Fries intended the true 
Sphaeria gyrosa Schw. to represent the type of his genus Endothia, 
as he had a part of Schweinitz’s original collection at the time and 
never definitely placed any other species in the genus; hence, 
Sphaeria gyrosa Schw. should be adopted as the nomenclatorial 
type of the genus. It is clear from Fries’s writings and specimens 
that he knew Sphaeria radicalis Schw., as he had American speci- 
mens from Schweinitz as well as European collections at the time 
he founded this genus. He did not, however, apparently regard it 
as congeneric with S. gyrosa. His specimens of S. radicalis show 


. t 
ENDOTHIA PARASITICA AND RELATED SPECIES. 5 


eS el ee 


the typical perithecia with necks, whereas no perithecia have been 
found in any of Schweinitz’s specimens of S. gyrosa examined by 
the writers. Fries, in common with Schweinitz, regarded the pyc- 
nidial cavities of S. gyrosa as perithecia. When the pycnidia of S. 
gyrosa are mistaken for perithecia and compared with the real 
perithecia of S. radicalis the differences appear marked. It was 
therefore quite as natural for Fries to place the two species in 
different genera as it had been for Schweinitz to place them in dif- 
ferent tribes of the genus Sphaeria. Fries’s mistake in describing 
as perithecia the pycnidial cavities in the stroma of S. gyrosa ex- 
plains his reference to the asci as “ascis diffluentibus.” Believing 
that he had perithecia but finding no asci, he interpreted this as 
indicating that they had disappeared. 

According to the plan of accepting only names originally applied 
to the ascospore stage, this name would be invalid, as proposed by 
Fries, and would be attributed to De Notaris, who placed the peri- 
thecial form of Sphaeria radicalis Schw. in the genus and described 
the ascospores. There is not the slightest question, however, in 
regard to the identity of the different stages of this fungus and 
their genetic connection, and the name Endothia has been almost 
invariably applied to these two species in both stages. 


SYNONYMY. 


There are only two true generic synonyms of Endothia: En- 
dothiella Saccardo, 1906 (71, p. 278) and Calopactis H. and P. 
Sydow, 1913 (81, p. 82). Endothiella was based on Endothiella 
gyrosa Sacc., which, according to authentic specimens from Saccardo, 
is undoubtedly the pyenidial form of E'ndothia flwens as found in 
Italy. Calopactis was based on C. singularis, the pycnidial condi- 


tion of Endothia singularis (H. and P. Syd.) S. and S. Ascospore 


cultures of this have not yet produced any pycnidia, but the proof 
of the genetic connection of the two stages appears rather con- 
clusive from the occurrence of pycnidia and perithecia in the same 
stroma, as shown in Plate XII. Perithecial stromata and ascospores 
were also found in the specimen of the Sydow exsiccati in the Patho- 
logical and Mycological Collections of the Bureau of Plant Industry. 

Von Hohnel (43, p. 1479-1481) considers Cryphonectria Sace. as a 
synonym of Endothia, taking C. gyrosa (B. and Br.) as the type of 
that genus because it is the first species listed by Saccardo in con- 
nection with his description of the genus. Saccardo, however, had 
previously established Cryphonectria as a subgenus, with (. abscon- 
dita as the type, which is not an Endothia. Valsonectria is also con- 
sidered by Von Héhnel a synonym of Endothia, but apparently he had 
not compared specimens of Spegazzini’s fungus, which is found upon 
examination of the type species to be separate from Endothia. The 


6 BULLETIN 380, U. S. DEPARTMENT OF AGRICULTURE. 


Tulasnes (88, p. 87-89) do not appear to have regarded Endothia as 
distinct from Melogramma, to which they referred /. gyrosa. The 
type of Melogramma, however, is 1/7. melogramma. (Bull.), which has 
a somewhat similar stroma, but the ascospores are 3-septate and dark 
colored and the perithecia not separable from the stroma, while the 
pycnospores are long, slender, and curved. 


STUDY OF EARLY COLLECTIONS AND TYPES. 


There has always been more or less uncertainty in regard to the 
identity of the older species of this genus of fungi. In order to get 
more light on this subject, a thorough study of all the available ma- 
terial in the way of literature, type specimens, and manuscripts was 
made. The first species to be described in this country was Sphaeria 
gyrosa Schw. ‘This was collected by Schweinitz at Salem, N. C., and 
published in 1822 (72, p. 3).1. Two hosts were given in the original 
description, Fagus and Juglans. 

As Schweinitz’s description was prepared before the advent of 
careful microscopical studies and spore measurements, it is impossible 
to identify the organism satisfactorily from the original description. 
It was, therefore, important, if possible, to locate the type specimens 
upon which the description was based. Schweinitz’s herbarium was 
left at his death, in 1834, to the Philadelphia Academy of Science. 
His specimens of fungi at the time they were transferred to the acad- 
emy were contained in small, folded paper packets, as shown in Plates 
V and VI. These packets were then inclosed in other heavy paper 
wrappers, folded to small quarto size, and three or four of these large 
packets, each bearing a manuscript lst of the species contained, were 
then inclosed in quarto pasteboard covers, tied with tape. The in- 
dividual species packets were labeled in Schweinitz’s handwriting, 
with the name of the species and the locality of the collection, as 
shown in Plate V, figure 2. 

These species packets frequently bore the names of several locali- 
ties, but usually two, Salem [N. C.] and Bethlehem | Pa.], as most of 
his collecting was done at these places. This fact, in addition to the 
evidence afforded by the specimens in the packets, clearly indicates 
Schweinitz’s method of handling his specimens. 

Frequently some of the specimens in a packet show the remains of 
a gummed strip. This will be noticed in Plate III, which indicates 

124, Sphaeria gyrosa Sz. 

S. subperipherica minor gregaria subconfluens aurantio miniata, sphaerulis gyrosis farc- 
tis demum prominulis pulverulentis, stromate lutescenta. 

In cortice nondum corrupto etiam vivo Fagorum et Iuglandum. Junior planiuscula, ubi 
adolevit sistit corpus subrotundum, tuberculis minimis et magoribus asperum et gyrosum. 
Sphacrulae farctze, teretes, supra gyrosae, paucae, radiatim divergentes a superficie ad 
centrum fere stromatis continuantur, primum sublantes, demum prominulae, cortice pul- 


verulento; ipsum tamen centrum farinacea carne componitur. Gelatina asciphora albet. 
Ostiola indistincta.—Transitum facit ad Sphaerias septimae divisionis. 


meee eee ee 


EE —— 


el ey 


ENDOTHIA PARASITICA AND RELATED SPECIES. 7 


that at one time the specimen was apparently attached to a sheet 
by a gummed paper strip. This seems to have been the way in which 
Schweinitz originally mounted his specimens, but later, apparently, 
he changed to the plan of putting them in paper packets and removed 
those which had been attached to sheets. It is clear from an examina- 
tion of the specimens still found in some of the original packets 
that two or more different hosts were sometimes included. In some 
cases as many as four or five different collections appear to have been 
placed in the same packet and each new locality added on the out- 
side. This method of keeping specimens makes it rather difficult in 
some cases to determine which belongs to the first collection. In the 
case of Sphaeria gyrosa but two localities are indicated on the packet, 


_ Salem and New England. (See Pl. VI, fig. 2.) 


The difficulties in determining the true type specimen of any 
species would have been sufficiently great if the collection had been 
preserved as it was left by Schweinitz. The matter is, however, 
further complicated by the later handling and rearrangement of the 
collection. Some time after Schweinitz’s death (the exact date the 
writers have been unable to determine) his collection of fungi was 
more or less completely rearranged and mounted. The greater part 
of this work was evidently done by Dr. Ezra Michener. Dr. Mich- 
ener was a lifelong resident of Chester County, Pa. He early be- 
came interested in botany, and in 1840 was elected a correspondent 
of the Philadelphia Academy of Natural Science. He paid special 
attention to the collection and study of fungi and corresponded and 
exchanged with various mycologists, especially Curtis and Ravenel. 
He left a large collection of fungi, which the writers have recently 
had the privilege of examining. Among his specimens are found 
many labeled “ Ex. Herb. Schw.”, which are undoubtedly part of 
Schweinitz’s original collections at the Philadelphia Academy. 
These specimens, as well as all of Michener’s fungi, are mounted in 
exactly the same manner as the mounted portion of Schweinitz’s col- 
lection at the Philadelphia Academy. The mounting paper, the 
specimen slips, the arrangement, manner of attachment, and the 
handwriting on the labels are identical, as will be readily perceived 
by comparing the illustrations from photographs of sheets from 
both herbaria. It is, therefore, clear that the mounted collection 
of Schweinitz’s herbarium was prepared by Dr. Michener. He evi- 
dently took from Schweinitz’s original paper packets what appeared 
to him to be the best or most typical specimen of the species in the 
packet and attached it with glue to a square slip of paper, as shown 
in Plate III. Where there was but little material in the original 
packet it was all mounted in this manner. In case there were several 
pieces in the original packet he used his own discretion in making 
the selection of the part to be mounted and the part to be left. 


8 BULLETIN 380, U. S. DEPARTMENT OF AGRICULTURE. 


When there were included in the original packet specimens from 
different hosts or different localities, in some cases representing dif- 
ferent species, it would have been difficult, if not impossible, to de- 
termine which was the original material from which Schweinitz’s 
description was made. At the same time, Dr. Michener, in case the 
specimen was not too scanty, evidently took a small portion of it 
for his own herbarium. Michener’s catalogue of his herbarium lists 
Sphaeria gyrosa Schw. Consulting his collection it is found that 
No. 1481, the number of Schweinitz’s specimen, is missing. Pin 
holes in the mounting sheet, however, show that the specimen which 
was once there has been removed. As perhaps throwing some light 
on the possible location of this specimen, it may be said that a speci- 
men apparently typical S. gyrosa, pycnidial form on beech, labeled 
by Dr. William Trelease as Sphaeria gyrosa from Pennsylvania, was 
seen in the Boissier Herbarium, Geneva. Dr. Trelease tells the 
writers that this specimen probably came from Dr. Michener, and 
as there is no evidence that Dr. Michener or any one else has col- 
lected /. gyrosa in Pennsylvania there is considerable probability 
that this specimen represents a portion of Schweinitz’s original col- 
lection. 

In most cases all of the material in Schweinitz’s original species 
packets was removed and either mounted or distributed. This was 
the case with Sphaeria gyrosa. The original packet of Schweinitz, 
which was fortunately preserved with all the others, is empty and 
apparently a part at least of the specimen which it contained is 
found in the mounted collection as prepared by Michener. This 
consists of a single piece of bark shown in Plate VI, figure 1. From 
the evidence the writers have been able to gather from Schweinitz’s 
manuscripts and correspondence, as well as from studies of his writ- 
ings and specimens in other herbaria, it appears that this specimen 
is the one indicated on the original packet and also by Schweinitz 
(74, p. 206) as having been collected in New England and sent to 
him by Torrey. This, as shown by his correspondence, was after he 
had left North Carolina. The bark upon which the fungus grew is 
clearly not Fagus, Juglans, or Quercus, the hosts originally given for 
S. gyrosa, but apparently Acer. It is therefore not a part of the 
original specimens from Salem, N. C., upon which his description 
was based, and in reality is not Sphaeria gyrosa, but a species of 
Nectria, which Schweinitz incorrectly identified as S. gyrosa. Por- 
tions of this same specimen are found in Berkeley’s herbarium at 
Kew and in the Curtis herbarium at Harvard. They are clearly the 
Nectria referred to above from Torrey. In this connection, it may 
be noted that E. Hitchcock in 1829 (42, p. 63) reports Sphaeria 
gyrosa Schw. from Amherst, Mass., and states in the preface to his 
list that Dr. Torrey assisted in the determination of the cryptogams. 


PLATE I. 
x 4. 


“CANKERS”? CAUSED BY ENDOTHIA PARASITICA ON CASTANEA DENTATA. 


Bul. 380, U. S. Dept. of Agriculture. 


a sian ee 


Bul. 380, U. S. Dept. of Agriculture. PLATE II. 


Vint Kbit = 


a AE De, 
; £ 


HERB. MUS. PARIS. 


‘ y, 
Le 2 : 
/te Ua VULOKYEVIL A Vee WW 


3 7 pi as Lae é 
ge gs ALG ae ZA S 


) ¢ & MECH: 
’ Bp eh bod Fla 7. C4 MO? i 
G ( Ex. ‘herb. Ad. Brongniart. Anno 1843 ). So qeaee 


ee ees 


Fic. 1.—PERITHECIA AND PYCNIDIAL STROMATA OF ENDOTHIA PARASITICA WITH CANKERS 
ON CASTANEA DENTATA. FIG. 2.—COTYPE OF SPHAERIA GYROSA SCHW. ON FAGUS. 


Specimen now in the Paris Museum sent to Brongniart by Schweinitz, showing Tulasne’s label 
‘*Melogramma gyrosum”’ and Schweinitz’s autograph label. 


Bul. 380, U. S. Dept. of Agriculture. PLATE III. 


443 f ~2ES Sytt Deedee 


oe NS ae oytcst —~ Sef Yyslewece eeecece corse See, 
G- SF <7ES 


. hee Engl ie ae Sa eee 


ee yao LEPy ee Lie 
L4IG2bF— Syze. Geerge | a Mr os 


Re ae : oh to hcebige Cri luecdiliee fei | 
fo frwree Casltzea Scfiev. a : ee See 


Sac lest =~7ECWs, : 


Ceceolerere frees 


SLES ALE. SY7t - Peeree-. 
oe 7 


a 


SUE e a We SUT! Ferg. 


»~ 


ts- etryfser pe eC if 


¢ 


PA ; a ¢ 7 
; i 2 : 3 
lai? Boe Sete, Sa hisice Gltilel. 


St Levit ewe), 


fit Bo > Oe ef «a7 t ee be a} LEED Lae ae 


Oy aa eae | 5 ; 4 z : * 
Le LA LS Alege ee ae a LYS LON LEL Ltt COLI OS Sete tet, 
eons . : ints ee : Sw. 


pT 


A SHEET FROM THE MOUNTED PORTION OF SCHWEINITZ’S HERBARIUM AT THE 
PHILADELPHIA ACADEMY OF SCIENCES, SHOWING SPECIMENS AS PREPARED AND 
LABELED BY MICHENER. 


Bul. 380, U. S. Dept. of Agriculture. PLATE IV. 


BETO: PERE wroinae sins. 


sy Sa Si eh aR 


JE 


. re * ‘ 2 rs 
), by Oh Ck ritpelbe lee Je 


‘eos cect h POD LEAMA IE . 


pp f OA bn a % 


* 


A SHEET FROM MICHENER’S HERBARIUM, SHOWING A PART OF SCHWEINITZ’S TYPE 
OF PEZIZA CINNABARINA (UPPER RIGHT HAND CORNER); ALSO. SHOWING CLEARLY 
THAT THE MOUNTING AND LABELING OF THIS AND SCHWEINITZ’S COLLECTION WERE 
DONE BY THE SAME PERSON. 


ENDOTHIA PARASITICA AND RELATED SPECIES. 9 


This seems to explain the origin of the specimen which Schweinitz 
received from Dr. Torrey. The writers have searched in vain for 
Endothia gyrosa in Amherst and vicinity and they know of no col- 
lections of the fungus from Massachusetts. No specimens upon 
which Hitchcock’s list was based have been located. 

Since it can be clearly shown that little or none of the original 
type collection of this species is in the Philadelphia Academy col- 
lection it must be looked for elsewhere. It is found by reference to 
Schweinitz’s correspondence and manuscripts, which have been care- 
fully examined by the writers through the courtesy of the Phila- 
delphia Academy and the descendants of Schweinitz, and also by 
studies in foreign herbaria that he divided his specimens with many 
of his European and American correspondents. As he does not ap- 
pear to have kept any duplicates separate from his regular collection 
it seems probable that the specimens he distributed were taken from 
the original packets. Thus in some cases, apparently all of a type 
specimen was removed from the original packet. In fact, in one 
instance (73, p. 5) he states that he sent his only specimen of a 
species of Hypoxylon to Dr. Schwaegrichen, of Leipzig. 

It seems rather certain from statements made by Schwaegrichen 
in his introduction to Schweinitz’s paper on the fungi of North 
Carolina (72) that specimens of a large number, if not all, of the 
species represented in that work were sent to him. The types or 
parts of the types should therefore be found in Schwaegrichen’s 
herbarium. In spite of all their efforts, however, through correspond- 
ence and personal search in Europe, the writers have been unable 
to locate Schwaegrichen’s collection of fungi. They found, however, 
in the herbarium of the University of Leipzig a small bit of a speci- 
men labeled “Sphaeria gyrosa Schwein. Juglans Fagus Carolina 
D. Schwaegrich. dd 5-21 K. Z.” This specimen is evidently a part 
of the original collection of Schweinitz which was sent to Schwaeg- 
richen and given by him to Dr. Kunze. The host is apparently 
neither Juglans nor Fagus, but seems to be Quercus. It may be 
noted in this connection that in spite of diligent search by the 
writers and various other collectors no specimen of Endothia has 
yet been found on Juglans in this country. Neither have the writers 
been able to find any specimen in the various herbaria examined. 
They have concluded, as a result of their studies, that the mention 
of Juglans by Schweinitz was an error in the identification of the 
host, which it is believed was really Quercus, the host upon which 
E. gyrosa is most frequently found in the South, and especially in the 
vicinity of Salem. According to the Aichi Code,' however, the 
specimen which should be taken as the type in this case is the one on 


1 American Code of Botanical Nomenclature. Canon 14, b. Bulletin, Torrey Botanical 
Club, vol. 34, p. 172. 1907. 


10 BULLETIN 380, U. S. DEPARTMENT OF AGRICULTURE. 


Fagus, as this is the first-mentioned host in the original description. 
No specimen of this species on Fagus from Schweinitz was found in 
Kunze’s collection. However, authentic specimens from Schweinitz 
on Fagus have been found in Fries’s herbarium at Upsala, in 
Hooker’s herbarium at Kew, and in Brongniart’s herbarium in the 
Paris Museum. The last, which is the largest and best specimen, 
is shown in Plate II, figure 2. Microscopic studies of the specimens 
at Paris and Kew show only pycnidia with pycnospores. The writers 
were unable to examine microscopically the specimen in Fries’s herba- 
rium, but it agreed in all macroscopic respects and also, so far as 
could be determined with a hand lens, with the Paris and Kew speci- 
mens. These specimens agree with all the material collected on Fagus 
from various localities in the South. Studies of numerous collec- 
tions of #. gyrosa have shown that the pycnidial form can be dis- 
tinguished with certainty from any of the other species of Endothia 
at present known. ‘The connection between this pycnidial form and 
the perithecial form as described has been demonstrated by pure 
cultures from ascospores and also by the association of typical 
pycnidia and pycnospores with perithecia and ascospores in the 
same stroma. ‘There appears to be no reasonable doubt, therefore, 
that the specimens collected by Schweinitz on Fagus were the 
pycnidial form of Hndothia gyrosa, and the specimen in the Paris 
Museum which was sent by Schweinitz to Brongniart about 1825 
may properly be considered a cotype of Schweinitz’s species. The 
specimen from Schweinitz in Kunze’s herbarium at Leipzig also 
proves on microscopic examination to be the pycnidial form of the 
same fungus. It is probable from the evidence at hand that 
Schweinitz did not collect any specimen showing ascospores of this 
fungus. However, the specimen in Kunze’s herbarium shows some 
perithecia evidently immature and without spores. A part of the 
specimen from Schweinitz in Fries’s herbarium shows stromata on a 
piece of bark, evidently not Fagus, but probably Quercus. This 
also appears to be pycnidia only. 

The specimen referred to by Clinton (18), which was found in 
the original packet of Schweinitz at Philadelphia with Sphaeria 
enteromela, is also undoubtedly the pycnidial form of /. gyrosa, 
which closely resembles some early stages in the development of 
species of Hypoxylon, especially H. enteromela. These species 
may be easily confused with each other, and this would seem to be a 
probable explanation of the accidental presence of this specimen in 
this packet. Another point of interest in this connection is the fact 
that in spite of diligent search on the part of the writers and many 
other collectors and an examination of numerous specimens of En- 
dothia on Fagus in all stages of development and from different 
localities only H'ndothia gyrosa has been. found on this host. Of 


ENDOTHIA PARASITICA AND RELATED SPECIES. 11 


course, it can not be positively stated that 4’. fuens does not occur 
on Fagus in this country, but if it does it must be rare. In this con- 
nection, it is also perhaps worthy of note that, notwithstanding the 
mention of Fagus as a host in Europe, the writers have never seen 
any European specimens of Endothia on this host. The specimens 
so named by Roumeguere and distributed as No. 989 Fun. Gal. on 
beech are, according to several specimens examined, evidently a 
young condition of some Hypoxylon, probably HZ. coccineum, which 
in this state bears a superficial resemblance in form and color to the 


_ stromata of Endothia, but can be easily distinguished by the dark- 


brown or blackish color of the interior of the stroma. The identity 
of Schweinitz’s Sphaeria gyrosa with the long ascospore form of 
Endothia shown on Plate VII is based on careful microscopic 
study of the stromata and measurement of the pycnospores from 
four specimens of the original collections of Schweinitz in North 
Carolina, three on Fagus and one labeled Juglans. The three on 
Fagus show the typical pycnidial stromata and pycnospores of the 
species, either of which is sufficient for positive identification when . 
thoroughly known. The specimen referred to by Schweinitz as on 
Juglans also shows typical pycnospores of /’. gyrosa. The evidence, 
as stated above, leaves no reasonable doubt as to the identity of the 
fungus which Schweinitz described as Sphaeria gyrosa. 

According to a specimen which is probably a portion of Schwei- 
nitz’s type found in Michener’s herbarium, Peziza cinnabarina 
Schw. is the pycnidial form of /. gyrosa (Schw.) (See PL. IV.) 
It is the form with small pycnidia on bare wood of Liquidambar. 
This was first reported by Schweinitz as “ Peziza flammea A. and 8S.” 
and later changed as above. Later Saccardo (69, vol. 8, p. 399), 
thinking that this was a Discomycete, transferred it to the genus 
Lachnella. 

The other American species of Endothia which was described by 


_ Schweinitz as Sphaeria radicalis and first published by Fries in 1828 


(31, p. 73) has also until recently been more or less misunderstood. 
The only specimens of this species found at present in Schweinitz’s 
mounted collection at the Philadelphia Academy of Science is a 
small piece of bark of an oak root bearing a few pycnidial stromata. 
No host was given in Fries, but Schweinitz in 1832 (74 p. 197) gives 
Fagus as the host. That this was an error and that the host was 
really Quercus and not Fagus is clearly indicated by all of Schwei- 
nitz’s specimens examined, not only those in the Philadelphia 
Academy but those found in several herbaria in Europe and one in 
Curtis’s herbarium at Harvard, and also in Schweinitz’s autograph 
label on the original packet in his herbarium. A photograph of this 
packet is shown in Plate VI. 

The description of this species was a published by Fries in 
1828 (31, p. 73). Sehweinitz’s snecimen at the Philadelphia Academy 


12 BULLETIN 380, U. S. DEPARYMENT OF AGRICULTURE. 


shows only pycnidia. (See Pl. V, fig. 2.) His description, how- 
ever, as well as his unpublished illustrations preserved in the library 
of the Academy, show clearly that perithecia were present in the 
material from which the description was made. This is also con- 
clusively shown by authentic specimens from Schweinitz in at least 
two European collections, those of Fries at Upsala and Hooker at 
Kew. A microscopic examination of these specimens shows good 
perithecia and mature ascospores having the characters and meas- 
urements given elsewhere in this paper for E'ndothia fluens (Sow.). 
(See Pl. XVII, fig. 9.) As there is no indication in Schweinitz’s 
writings or in his manuscript notes and records that he made more 
than one collection of this species, there is no reason to doubt that 
the material at Upsala and Kew is a part of that upon which he 
based his description of Sphaeria radicalis Schw. The true type 
specimen of the species is that in Fries’s herbarium upon which he 
based his description, which was added to the diagnosis sent by 
Schweinitz. 

One year after the description of this species from America it 
was reported from Italy by Rudolph, in 1829 (66, p. 393), and in 
1830 Fries (32, p. 541) himself reports the fungus from France. 
This species had, however, been collected and described before 
in its pyenidial condition in 1814 by Sowerby (79, pl. 438) under 
the name of Sphaeria fluens. This was reported in 1836 by Berkeley 
(8, p. 254) as Sphaeria gyrosa Schw. A microscopic study of the 
original material of this species, which was collected by Charles 
Lyell on chestnut in the New Forest in southern England and is 
now preserved in the Kew Herbarium, leaves no doubt that it is 
the pycnidial form of Endothia radicalis (Schw.). Plate XVII, fig- 
ure 3, shows pycnospores from Sowerby’s specimen at Kew. This 
specimen agrees with Sowerby’s illustration and is apparently the 
one from which this figure was made. The pycnospore masses 
are somewhat larger than usual; otherwise it is typical of 7. radi- 
calis Schw. 

At first it did not seem possible to distinguish the species of 
Endothia in their pyenidial condition, but thorough microscopic 
studies of large quantities of material in the field and laboratory in 
both America and Europe have shown that the two sections of the 
genus and some of the species can usually be separated with cer- 
tainty in this stage of their development, as indicated by the tables 
of measurements and in the photographs of pyenospores, and es- 
pecially by the stromata of the different species. 

The first description of the ascospores of /. radicalis was given 
in 1858 by Currey (21, p. 272), who examined the specimens from 
Schweinitz in Hooker’s herbarium at Kew. Currey figured what 
he believed to be four ascospores. Two are apparently typical 72. 


ENDOTHIA PARASITICA AND RELATED SPECIES. 13 


fluens; the other two are more than 1-septate and belong to some 
other organism. Cesati and De Notaris, in 1863 (11), first definitely 
referred Sphaeria radicalis Schw. to Endothia. Up to this time 
Sphaeria gyrosa and Sphaeria radicalis were generally regarded by 
mycologists as separate species and were placed by Schweinitz and 
Fries in different groups of the genus Sphaeria, though they both 
mention a similarity in external appearances. 

In 1863 the Tulasnes, in their epoch-making work on the fungi 
(83, pp. 87-89), made a careful microscopic study of the specimens 
from Schweinitz preserved in the Paris Museum and also specimens 
received from De Notaris, Berkeley, and other collectors. At that 
time no ascospores of Sphaeria gyrosa had apparently been described 
by mycologists. The material of S. gyrosa from Schweinitz which 
the Tulasnes found in the Paris Museum included the specimen on 
Fagus which had been sent by Schweinitz to Brongniart. There 
seems to be no evidence that the Tulasnes examined other specimens 
from Schweinitz or that they examined any specimens showing asco- 
spores of the true Sphaerta gyrosa. This is indicated by their de- 
scription and measurements of the ascospores. From their studies of 
Schweinitz’s specimens and from other Carolina specimens sent them 
by Berkeley they concluded that Sphaeria gyrosa and Sphaeria radi- 
calis are the same species and called it /elogramma gyrosum. 

Fries (83, pp. 885-3886) had earlier (1849) reported Sphaeria gyrosa 
as occurring in southern Europe. ‘This report was apparently based 
upon specimens of pycnidial stromata of #’. fuens, somewhat larger 
and more irregular in shape than usual, collected in western France 
by Guepin and Levieux and already referred to. 

The statement of the Tulasnes (83, pp. 84-89) in regard to the 
identity of these species was accepted by practically all mycologists 
down to 1912, when the discussion in regard to the origin and 
relationships of Hndothia parasitica commenced. Ellis and Ever- 
hart in 1892 (26, p. 552) apparently figured the true LZ. gyrosa Schw. 
but cited exsiccati of both LZ’. gyrosa and EF. fluens and gave the 
ascospore characters and measurements of /. fluens, apparently 
copied from Winter (85, p. 803), as the spores figured do not agree 
with the description. 


THE SPECIES OF ENDOTHIA. 


ENDOTHIA Fries, 1849, Sum. Veg. Scand., p. 385.1 


SYNONYMS: 
Endothiella Sace., 1906, in Ann. Mycol., v. 4, no. 3, p. 273. Type species, 
EH. gyrosa Sace., 1 ¢. 
Calopactis H. and P. Syd., 1912, in Ann. Mycol., v. 10, no. 1, p. 82. Type 
species, C. singularis, 1 ¢. 


1 All references to literature in synonymy are given in full in “ Literature cited,” p. 77. 


14 BULLETIN 380, U. S. DEPARTMENT OF AGRICULTURE. 


Stromata subcorticular in origin, variable in size and shape, 
pustular to .subspherical, subcoriaceous to friable, sometimes con- 
fluent, surface light auburn? or chestnut to mahogany red, capucine 
vellow or cadmium orange to scarlet within; pycnidial and peri- 
thecial stromata the same or similar; pycnidia few to numerous, con- 
sisting of simple cavities or complex and irregular chambers; 
pycnospores minute, simple, bacilliform to oblong, yellowish to 
reddish in mass; perithecia deeply immersed, in one or more irregu- 
lar layers, usually black when mature, with long necks, black 
within, colored like the stroma without; asci clavate to oblong fusoid, 
8-spored, usually without paraphyses; ascospores oblong fusoid or 
subellipsoid to cylindric or allantoid cylindric, uniseptate or non- 
septate, hyaline to pale yellowish. 


Section 1.—Ascospores short cylindric to allantoid, continuous or 
pseudoseptate. 


ENDOTHIA GYROSA (Schw.) Fries, 1849, Sum. Veg. Scand., p. 385. p. p. 


SYNONYMS: 
Pycnidia: Sphaeria gyrosa Schw., 1822, Syn. Fung. Car. Sup., p. 29, no. 24. 
Peziza flammea Schw. (not. Alb. and Schw.), 1822, Syn. Fung. Car. Sup., 
p. 98, no. 41, p. p. ad Liquidambar. 
Sphaeria gyrosa Fries, 1822, Syst. Mycol., v. 2, p. 419. 
Peziza gyrosa Spreng., 1827, Syst. Veg., v. 4, pars. 1, p. 515. 
Peziza cinnabarina Schw., 1832, Syn. Fung. Am. Bor., p. 173. 
Melogramma gyrosum, L. R. and C. Tul., 1863, Selecta Fung. Carpol., t. 2, 
PPS.’ “Pp: ‘Pr Wau: 
Melogramma gyrosum M. A. Curtis, 1867, Cat. Indig. Nat. Plants, p. 148. 
Endothia gyrosum (Tul.) Fekl., 1869, Symb. Mycol., p. 226. 
Melogramma gyrosum Tul., Rav., 1879, Fung. Amer. Exs., no. 352. 
Lachnella cinnabarina Sacce., 1889, Syll. Fung., v. 8, p. 399. 
Perithecia: Sphaeria gyrosa Schw., Rav., 1852, Fung. Car. Exs., no. 49. 
Melogramma gyrosum Tul., Cooke, 1878, in Ann. N. Y. Acad. Sci., v. 1, no. 
5/6,epr 185: ; 
Endothia gyrosa Fckl., Sacc., 1882, Syll. Fung., v. 1, p. 601. p. p. min. 
Endothia gyrosa Schw., Ell. and Ev., 1887, No. Amer. Fung. Exs., no. 1956. 
Endothia gyrosa (Schw.) Ell. and Ev., 1892, No. Amer. Pyren., p. 552, p. p. 
Endothia radicalis (Schw.) Farl., Clint., 1912, in Science, n. s., v. 36, no. 
939, p. 908. 
Endothia radicalis (Schw.) Shear, 1912, in Phytopathology, v. 2, no. 5, p. 
He ie Es 
Endothia radicalis (Schw.) Fries, P. J. and H. W. And., 1912, in Phyto- 
pathology, v. 2, no. 5, p. 210. 
TYPE SPECIMEN.—The type in Herb. Schw. is wanting. A cotype is in Herb. 
Museum of Paris. 
Pycnip1A.—Stromata corticular or subcorticular, pulvinate to tubercular, 
rugulose, scattered or gregarious, occasionally confluent, 1.5 to 3 mm. in diame- 
ter by 1.5 to 2 mm. high, orange chrome when young to chestnut when mature, 


1In the following descriptions of cultures and elsewhere throughout this paper, the 
names of colors are taken from Ridgway’s recent work on color nomenclature (64). 


ENDOTHIA PARASITICA AND RELATED SPECIES. 15 


becoming almost black when old and weathered, cadmium orange within; 
pycnidia consisting of numerous irregular labyrinthiform chambers in the 
stroma, separated by walls of varying thickness and opening by irregular pores 
in the surface of the stroma; sporophores cylindric or slightly tapering toward 
the apex, 6 to 9 » long; pycnospores oblong, straight or sometimes slightly 
curved, appearing hyaline when separate, warm buff to ochraceous buff or 
darker, according to mass and moisture content, 8 to 4 by 1.5 to 2 wu. 

PERITHECIA.—Stromata the same or similar to those producing pycnidia; 
perithecia dark, membranous, few to many, mostly 25 to 50, usually arising 
in the lower portion of the stroma, 150 to 300 uw in diameter, very irregularly 
arranged in one to several layers, prolonged into slender necks which penetrate 
the stroma above and sometimes protrude somewhat, terminating in a short 
conical ostiole; asci oblong fusoid or subclavate, very short stipitate, 25 to 30 
by 6 to 7 u; ascospores irregularly biseriate, cylindric to allantoid, 7 to 11 by 
2 to 3 uw, mostly 7.5 to 10 by 2 to 2.5 uw, hyaline when separate, slightly yellowish 
in mass, with a very thin gelantinous envelope when mature. 

CULTURAL CHARACTERS.—Cultures one month old on white corn meal show an 
abundant thick growth of mycelium producing irregular tubercular masses 
resembling pycnidial stromata, but without spores. The surface color is 
capucine buff. The medium usually changes to perilla purple. It is distin- 
guished from HH. singularis, its nearest relative, by its more rapid growth and 
the formation of the large tubercular masses. 

Hosts.—Exposed roots and branches: Quercus alba, Q. coccinea, Q. falcata, Q. 
georgiana, Q. ilicifolia, Q. imbricaria, Q. marylandica, Q. nigra, Q. phellos, Q. 
prinus, Q. rubra, Q. velutina, Q. virginiana, Liquidambar styraciflua, Fagus 
americana and F. sylvatica cult. vars., Castanea dentata and cult. vars., and 
Vitis sp. (25). 

A specimen of this species collected by Ravenel has the host given as maple 
(Acer), but microscopic examination shows it to be Liquidambar. 

TYPE LOCALITY.—Salem, N. C. 

GEOGRAPHICAL DISTRIBUTION.—Southwestern Connecticut to eal Michigan, 
southward to Florida and Texas; alsc Kansas and California. 

ILLUSTRATIONS.—HIll. and Ev., 1892, No. Amer. Pyren., pl. 36, fig. 68; Clint. 
1913, in Conn. Agr. Exp. Sta. Rpt., 1911, 1912, pl. 28, fig. a, d, and g. 

ExsiccatTi.—Pycnidia: Baker, Pl. Pac. slope, 722, on Quercus agrifolia; Rav. 
Fung. Amer., 352, on Quercus. Perithecia: Ell. and Ev. No. Amer. Fung., 1956, 
on Quercus; Rav. Fung. Car., 49, on Quercus and Liquidambar. 


ENDOTHIA SINGULARIS (H. and P. Syd.) S. and S. nov. comb. 


SYNONYMS: 
Pycnidia: Calopactis singularis H. and P. Syd., 1912, in Ann. Mycol., vol. 10, 
ie. fp. 82. 
Endothia gyrosa Ell. and Ey., in Herb. N. Y. Bot. Gard. 
Endothia gyrosa (Schw.) Fekl. Hohnel, 1913, in Sitzber, K. Akad. Wiss. 
[Vienna], Math. Naturw. K1., Abt. 1, Bd. 122, Heft 2, p. 298. 
TYPE SPECIMEN.—H. and P. Syd., Fung. Exot, no. 88, on Q. gambellii. 
Pycnip1A.—Stromata corticular, erumpent, depressed globose, sometimes ir- 
regular, scattered, or gregarious, 3 to 5 mm. wide by 2 to 4 mm. high, outer wall 
thick, coriaceous, becoming brittle, mahogany red without, scarlet within; pyc- 
nidia consisting of innumerable nearly spherical cavities throughout the stroma, 
25 to 35 uw in diameter, the walls disintegrating into a powdery mass and the 
whole set free by the irregular rupture of the stroma wall, usually leaving a cup- 
like basal portion attached to the bark; sporophores, according to the Sydows, 


16 BULLETIN 380, U. S. DEPARTMENT OF AGRICULTURE. 


short, hyaline, subulate, 6 to 8 by 1 uw; pycnospores ovoid oblong, hyaline, the 
contents of each pyecnidial cavity adhering in a globular mass, when set free, 
& to 4 by 1 to 1.5 pw. 

PERITHECIA.—Stromata the same or similar to those producing pycnidia; 
perithecia membranous, few to many, usually 100 or more, 200 to 350 w in 
diameter, irregularly arranged in several series, prolonged into slender necks 
which sometimes protrude from the stroma; ostioles depressed conical; asci, 
oblong cylindric or subclavate to fusoid, substipitate, 25 to 35 by 4.5 to 5.5 uw; 
ascospores irregularly biseriate, cylindric to allantoid, with a thin gelatinous 
envelope, hyaline when separate, slightly yellowish in mass, 7 to 11 by 1.5 to | 
3 «3; mostly 7.5 to 10 by 2 to 2.5 um. 

CULTURAL CHARACTERS.—Cultures one month old on white corn meal have a 
cadmium and orange to capucine buff mycelium. It is distinguished from 
EH. gyrosa by its slower growth and brighter color and the want of tubercular, 
stromalike masses. No spores of this species have been produced in any of 
the writers’ cultures. . 

Hosts.—Quercus gambellii, Q. leptophylla, Q. nitescens, Q. utahensis. Bethel 
also reports it on Q. pungens. 

TYPE LOCALITY.—Palmer Lake, Colo. 

GEOGRAPHICAL DISTRIBUTION.—Colorado and New Mexico. 

ILLUSTRATIONS.—Pyenidia: H. and P. Syd., 1912, in Ann. Mycol., vol. 10, no. 1, 
p. 82, figs. 1-5. 

ExsiccaTi.—Pyecnidia and perithecia: H. and P. Syd., Fung. Exot., 88, on 
Quercus. Pycnidia: Bart. Fung. Col., 4002, on Quercus utahensis. 


In shape and size of pycnospores and ascospores this species closely 
resembles Z'. gyrosa, but is easily separated by the much greater size 
of its stromata, its brighter color and very numerous, small, regular 
pycnidial cavities and more numerous perithecia, as well as its geo- 
graphical distribution. 

The specimens of the Sydow exsiccati, No. 88, in the Pathological 
and Mycological Collections of the Bares of Plant Industry show 
both pycnidia and perithecia. 


Section 2—Ascospores oblong fusiform to oblong ellipsoid, uni- 
septate when mature. 


ENDOTHIA FLUENS (Sow.) S. and S. nov. comb. _ 


SYNONYMS: { 
Pycnidia: Sphaeria fluens Sow., 1814, Col. Fig. Engl. Fungi, Sup. pl. 438, 
ngs: 1; 2. 


Sphaeria gyrosa Berk., 1836, Brit. Fungi, p. 254. Not Schw. 

Endothia gyrosa Fries, 1849, Sum. Veg. Scand., p. 385. p. p. Europ. 

Sphaeria radicalis Fckl., 1861, Enum. Fung. Nass., p. 76, no. 640. 

Endothia gyrosum Fckl., 1869, Symb. Mycol., p. 226. p. p. spec. cit. 

Endothia gyrosa (Schw.) Fckl., forma castaneae vescae Sacc., 1876, Mycol. 

Ven. Exs., no. 929. 

Endothiella gyrosa Sace., 1906, in Ann. Mycol., v. 4, no. 3, p. 278. 
Perithecia: Sphaeria radicalis Schw., Fries, 1828, Elenchus Fung., v. 2, p. 73. 

Sphaeria radicalis Schw., Rudolphi, 1829, in Linnaea, Bd. 4, Heft 3, p. 393. 

Sphaeria radicalis Schw., Fries, 1830, in Linnaea, Bd. 5, Heft 4, p. 541. 


Bul. 380, U. S. Dept. of Agriculture. PLATE V. 


(ROLL, 


=~ 


oy f) cy. a a 
Ai’ “ io ee eae f itd pe os 


4 
. 
Lilathty AA _V pact Leable gtt¢¥- aff rr by, vee es 
Birt, UW CCLCOVLIS $77 AL kaPold Oe ee, the 
oo a 


ff FILtf a fA SALLE AOL Qrecent, ae 2} Shes Vr 7.e- j 
ae fr, : Te Mais | am C32 FAA - : 7 


Pope titid 


A od ned WAL Cikcermfze thd ECC Of ee oe (rach cals 


| fbr fear Ma rege , ectartio onrnota, (UbrI21hee 
f* 1a tbe ta A laid ci ee) C2T LLL batts te abvcaidinea)s 
y. é Le a> 
pet lov srerles prise rrectes el toridilecest hited, Clt4t8 4a. 
eee Cots Cc 3 PE CAEAIL ACY - iy ¢ g “ Lege, | 


L Doth MP PL Shh Ce cf, b> Cotltta y tts clita, | 
pice. feye for fryer pee | te ete bilo; . pea 


ai Z thee PZ2S 
SLOUT ES Rhy: Les wig CO es ee 0 tet Geged noe oa Lact ficd. hcl 22 fre 
fr 


spd dD OL ho Loge gees O24 OPEL ae 
Gor pele lecp ak Car, % yf i 
1 


é 


L259 ee C2 Lyfe: Ce 


inn ee 


Salt Lattin radical | 
; sou ‘ 
Vea Lesry. 


Biavel AC seco 
pinercia tadcalg 


coi 


Fela 
te Aad Kvakt, Kites 


2 


Sjthcceee PL LLE ‘wee & Les — S cle: 


i 


Fia. 1.—PHOTOGRAPH OF SCHWEINITZ’S MANUSCRIPT NOTES, WITH HIS DESCRIPTION 
OF SPHAERIA RADICALIS.' FIG. 2.—SPECIMEN OF S. RADICALIS IN THE MOUNTED 
COLLECTION OF SCHWEINITZ, AS PREPARED BY MICHENER; ALSO ORIGINAL PACKET 
WITH SCHWEINITZ’S AUTOGRAPH LABEL. 


Bul. 380, U. S. Dept. of Agriculture. PLATE VI. 


VIB, AB 3 ~ a Ayae enews 


ee 


FiG. 1.—PHOTOGRAPH OF THE SPECIMEN IN SCHWEINITZ’S HERBARIUM MOUNTED BY 
MICHENER. NOT TRUE ENDOTHIA GYROSA BUT A NECTRIA. FiG. 2.—ORIGINAL 
PAPER PACKET IN WHICH SCHWEINITZ’S TYPE MATERIAL OF E. GYROSA WAS PRE- 
SERVED, WITH HIS AUTOGRAPH LABEL. 


Bul. 380, U. S. Dept. of Agriculture. PLATE VII. 


ENDOTHIA GYROSA GROWING ON THE RECENTLY CUT END OF A LIVING BRANCH OF 
FAGUS SP. NATURAL SIZE. 


Iture. 


1cu 


U.S. Dept. of Agr 


380, 


Bul. 


MYCELIAL FANS OF ENDOTHIA PARASITICA UNDER THE BARK OF CASTANEA DENTATA. 


State Forestry 


. 


1a 


Pennsylvan 


iams, 


Department. 


Illustration from Heald (39), by courtesy of I. C. Will 


ENDOTHIA PARASITICA AND RELATED SPECIES. 17 


SynonyMs—Continued. 
Perithecia—Continued. 

Sphaeria radicalis Schw., 1832, Fun. Am. Bor., p. 197. 

Sphaeria radicalis Schw., Mont., 1834, in Ann. Sci. Nat. Bot., s. 2, t. 1, 
p. 295. 

Sphaeria (Diatrype) radicalis Fries, Currey, 1858, in Trans. Linn. Soe. 
London, v. 22, pt. 3, p. 272, pl. 47, fig. 89. p. p. 

Valsa radicalis Ces. and De Not., 1863, in Comm. Soc. Crittog. Ital., v. 1, 
p. 207. 

Endothia radicalis (Schw.) Ces. and De Not., 1863, in Comm. Soc. Crittog. 
Ital., v. 1, opp. p. 240. 

Melogramma gyrosum L. R. and C. Tul., 1863, Selecta Fung. Carpoi., t. 2, 
p. 87. p. p. max. 

Sphaeria (Diatrype) radicalis Schw., Currey, 1865, in Trans. Linn. Soc. 
London, v. 25, pt. 2, p. 244. 

Endothia gyrosa (Schw.) Fckl., Sacc., 1882, Syll. Fung., v. 1, p. 601. p. p. 

Endothia gyrosa var. rostellata Sacc., 1882, Syll. Fung., v. 1, p. 602. 

Endothia radicalis (Schw.) Wint., 1887, Pilze, p. 803. 

Endothia gyrosa Schw., Ell. and Ev., 1892, No. Amer. Pyren., p. 552. p. p. 

Endothia virginiana P. J. and H. W. And., 1912, in Phytopathology; v. 2, 
no. 6, p. 261. 

Endothia gyrosa (Schw.) Fries, Clint., 1918, in Conn. Agr. Exp. Sta. Rpt., 
1911-12, p. 425. 

Endothia pseudoradicalis Petri, 1913, in Atti R. Accad. Lincei Rend. Cl. 
Sci. Fis., Mat. e Nat., s. 5, v. 22, sem. 1, fase. 9, p. 654. 

Endothia gyrosa (Schw.) Feckl., Hohnel, 1913, in Sitzber. K. Akad. Wiss. 
[Vienna], Math. Naturw. Kl., Abt. 1, Bd. 122, Heft 2, p. 298. 

TYPE .SPECIMEN.—Sowerby in Herb. Kew. on Castanea sativa, New Forest, 
England. Coll. C. Lyell, Apr. 15, 1809. 

Pycnip1A.—Stromata corticular or subcorticular, truncate conical to pulvi- 
nate, usually separate and gregarious, but frequently confluent, 0.75 to 3 mm. 
in diameter by 0.5 to 2.5 mm. high, compact, varying from light auburn to 
chestnut on the surface and capucine yellow to cadmium orange within; 
pycnidia consisting of simple or more or less complex and irregular chambers 
in the stroma, opening by an irregular pore or slit at the apex of the stroma; 
sporophores usually simple, sometimes branched near the base, eylindric to 
subclavate, 10 to 13 w long, sometimes 24 to 30; pycnospores oblong to rod- 
like, pale yellowish in mass, 3 to 5 by 1.5 to 2 uw, mostly 3.5 to4 by 2m. | 
is. _ PERITHECIA.—Stromata the same or similar to those producing pycnidia ; 
perithecia membranous, few to many, mostly 15 to 25, 300 to 400 uw in diameter, 
usually arising in the lower portion of the stroma, irregularly arranged in one 
- to three layers, prolonged into slender necks which penetrate the stroma above 
and protrude usually from 300 to 600 yw, terminating in conical ostioles; asci 
oblong fusoid or subclavate, very short stipitate, 30 to 40 by 6 to 8 uw, mostly 
30 to 85 by 7 mw, ascospores irregularly biseriate, oblong fusoid or subellipsoid, 
not constricted at the septum, hyaline with a thin gelatinous envelope, 6 to 10 
by 3 to 4.5 uw, mostly 6.5 to 9 by 8 to 4 wu. 

CULTURAL CHARACTERS.—Cultures one month old on white corn meal show a 
compact growth with a nearly smooth surface. The color ranges from light 

cadmium to empire yellow, and the medium becomes perilla purple. Pycnidia 
~ and spores usually appear a little later, forming large erumpent stromata 
which extrude thick masses of pycnospores. The light mycelium with large 


43737°—Bull. 380—17——2 


18 BULLETIN 380, U. S. DEPARTMENT OF AGRICULTURE. 


pycnidial stromata and spore masses are distinguishing characters on this 
medium. 4 

Hosts.—America: Exposed roots and Gratis of Q. alba, Q. coccinea, Q. 
marylandica, Q. prinus, QY. rubra, Q. velutina, and Castanea dentata. Europe: 
Specimens examined, Quercus pedunculata, Castanea sativa, Alnus glutinosa, 
Ulmus campestris, Carpinus betula, and Corylus sp. Japan: Castanea sp. and — 
Pasania sp. It is also reported on Aesculus, Fagus, and Juglans by Traverso. 

TYPE LOCALITY.—New Forest, England. 

GEOGRAPHICAL DISTRIBUTION.—America: Southern Pennsylvania and Ohio to 
South Carolina and northern Mississippi. Europe: Southern England, France, 
South Germany, and Switzerland to southern Italy and Transcaucasia. Asia: 
Japan. 

ILLUSTRATIONS.—Sowerby, 1814, Col. Fig. Engl. Fungi, Sup., pl. 4838; Currey, 
1858, in Trans. Linn. Soc. London, v. 22, pt. 3, pl. 47, fig. 89 (2 upper spores) ; 
Ces. and De Not., 1863, in Comm. Soc. Crittog. Ital., pl. 3; Sace., 1873, in Atti 
Soc. Veneto-Trentina Sci. Nat. Padova, v. 2, fase. 1, pl. 14, fig. 68-65; Sacc., 1883, 
Gen. Pyren., pl. 6, fig. 6; Ruhl., 1900, in Hedwigia, Ba. 39, pl. 2, fe, Oe Eeav:, 
1906, in Soc. Bot. Ital. Fl. Ital. Cript., pars 1, v. 2, fase. 1, p. 180, fig. 34; P. J. 
and H. W. And., 1913, in Penn. Chestnut Tree Blight Com. Bul. 4, p. 22, fig. 2, 
A and C; Clint., 1918, in Conn. Agr. Exp. Sta. Rpt., 1911-12, pl. 28, fig. b, e, 
h, and j; Petri, 1913, in Atti R. Accad. Lincei Rend. Cl. Sci. Fis., me e Nat., 
Vv. 20>. sem. 1, fase. 9, p. 656, fig. 1-3. 

ExsiccaTi.—Pyenidia: Thiim. Myc. Univ., 769, on Castanea; Sace. Myc. Ven., 
670, on Carpinus betula; Sace. Mye. Ven., 929, on Castanea. Perithecia: Fckl. 
Fun. Nass., 640, on Ulmus campestris; Erb. Critt. Ital., 986, on Castanea; Rab. 
Herb. Viv. Myec., 254, on Castanea. 

Roum. Fun. Sel. Gal., 989, labeled Endothia gyrosa Schw. on beech is appar- 
ently young Hypoxylon coccineum. 


The most important synonyms given here have already been dis- 
cussed. Of the others the writers have examined the types or col- 
lections upon which the identifications*were based. All the material © 
of Endothia in the herbaria of Cesati, De Notaris, Fuckel, and 
Berkeley, as well as other smaller collections, has been carefully 
studied. £. virginiana And. and And. has been studied in cultures, 
as well as typical specimens from the authors of the species, and 
agrees in every particular with 2. fluens. 

Through the kindness of Dr. Petri a part of the type of his 
E.. pseudoradicalis has been examined, but unfortunately no cultures 
could be obtained from the specimen. The writers have been unable 
to distinguish his specimen from forms of /#. fuens which appear to 
show all the intermediate conditions of variation connecting it with 
typical /’. fluens. The ascospores of /’. fluens are more variable in 
size and shape than those of any other species of Endothia studied. 
After examining many specimens of this species from Europe, it 
does not seem possible at present to separate any of them. The case 
of L. pseudoradicalis can not perhaps be regarded as closed until 
more material of it has been collected and compared in culture. In 
fact, the slide from the type of Sphaeria radicalis Schw. shows 
ascospores of both the narrow and broad form. The photomicro- 


ey i 


> 


ENDOTHIA PARASITICA AND RELATED SPECIES. 19 


graph, Plate XVII, fig. 9, shows an ascospore which agrees with 
Petri’s description and figures. 


ENDOTHIA FLUENS MISSISSIPPIENSIS S. and S. nov. comb. 


SYNONYM: 
Endothia radicalis mississippiensis Shear and Stevens in U. 8S. Dept. Agr., 
Bur Plant Indus. Cir, 131, p. 4:. 1918. 

TYPE SPECIMEN.—NO. 1782, on Castanea dentata, Blue Mountain, Miss., N. E. 
Stevens, Feb. 13, 1913. Deposited in Pathological and Mycological Collec- 
tions, Bureau of Plant Industry. 

CULTURAL CHARACTERS.—Cultures one month old on white corn meal show a 
compact, rather uniform surface, the color of the mycelium varying from cad- 
mium orange to xanthine orange. This variety is distinguished from the species 
by the color of its mycelium, by the numerous small pycnidia thickly scattered 
over the surface of the culture, and by the lack of any purple color in the 
medium. 

Hosts.—Castanea dentata, Quercus alba, and Q. velutina. 

GEOGRAPHICAL DISTRIBUTION.—Northern Mississippi, Kentucky, Tennessee. 

COLLECTIONS EXAMINED.—On Castanea dentata: No. 1706 A. pyenidia, Corinth, 
Miss2) 7.) B.. Snyder; ne. 708, pycnidia, Dumas, Miss., T. H. S.; no. 1782, 
ascospores, Blue Mountain, Miss., N. E. S.; no. 1806, ascospores, Blue Moun- 
tain, Miss., N. E. S. On Quercus: No. 1989, pycnidia, Danville, Ky., N. E. S.; 
no. 1995, pyenidia, Danville, Ky., N. E. 8.3; no. 2082, pyenidia, Lexington, Tenn., 
N. E. S.; no. 2255, pycnidia, Sardis, Miss., S. and S. 

No morphological characters have yet been found to distinguish this variety. 
It is therefore separated on its cultural characters, which are marked and 
constant. The plant was first collected by T. E. Snyder, of the Bureau of Ento- 
mology. 


ENDOTHIA LONGIROSTRIS Earle, 1900, in Muhlenbergia, v. 1, no. 1, p. 14. 


SYNONYM: . 
Perithecia : Diatrype radicalis (Schw.) Fries, Mont., 1855, in Ann. Sci. Nat. 
ome. t. 5, p. 123. *Not Schw. 

TYPE SPECIMEN.—No. 43840. <A. A. Heller, Plants of Porto Rico. In Herb. 
N. Y. Bot. Garden. 

PycNniIpIA.—Stromata corticular, erumpent, gregarious, sometimes confluent, 
1 to 3 mm. in diameter, subcoriaceous, surface orange rufous to chestnut, in- 
terior zinc orange; pycnidia consisting of irregular labyrinthiform cavities open- 
ing by a single large pore or irregular rupture at the apex of the stroma; 
sporophores slender, somewhat tapering upward, mostly 8 to 10 uw long; pyeno- 
spores oblong elliptic, hyaline or yellowish in mass, when expelled forming a 
stout spore horn or tendril, colored like the stroma on the outside, 2 to 4 
by 1 to 1.5 wu. 

PERITHECIA.—Stromata the same as those producing pyenidia, but larger and 
frequently confluent, forming linear series in crevices in the bark; perithecia 
arising usually at the base of the pycnidial stroma, mostly 3 to 10 in the sepa- 
rate stromata, membranous, 300 to 400 » in diameter, mostly in a single irregu- 
lar series, prolonged into long necks, 1.5 to nearly 1 em. long, sec. Earle, inter- 
nally black, externally same color and structure as the stroma; ostiole acute: 
asci oblong cylindric to fusiform, 25 to 35 by 5 to 7 wu, mostly 30 by 6 uw; asco- 
spores overlapping uniseriate to irregularly biseriate, hyaline, ovoid to ovoid 
elliptical, 6 to 8.5 by 3,to 4 uw, mostly 7 to 7.5 by 3 to 3.5 u,. 


20 BULLETIN 380, U. S. DEPARTMENT OF AGRICULTURE. 


CULTURAL CHARACTERS.—Cultures one month old on white corn meal have a 
uniform cadmium orange to xanthine orange color. The entire surface is covered 
with a compact growth, irregularly ridged. Tiny mars orange spore masses are 
scattered irregularly over the surface. Cultures of this species closely resemble 
EH. fluens mississippiensis on this medium, being distinguished by the smaller and 
much less numerous spore masses. The medium is changed to amber brown 
just below the mycelium, shading into mars yellow; whereas, in the case of 
EK. fluens mississippiensis the color of the medium is very little changed. 

TYPE LOCALITY.—‘‘ Calcareous hills east of Santurce, Porto Rico, se Sa 
Lott” 

GEOGRAPHICAL DISTRIBUTION.—Porto Rico and French Guiana. 

Exsiccati.—Pycnidia and perithecia: Heller, Plants of Porto Rico, no. 4340. 


This species, which appears to be subtropical or tropical in its 
range, 1s known at present from only three collections, the type col- 
lection from Porto Rico, a collection by Prof. N. Wille, No. 816, 


Porto Rico, distributed by the New York Botanical Garden, from 


which the cultures were obtained ; and one made by Leprieur, No. 392, 
in French Guiana, and determined by Montagne as Diatrype radicalis 
(Schw.). A specimen of this collection apparently labeled by Mon- 
tagne and preserved in the Delessert Herbarium at Geneva has been 
examined and found to agree with the type material of /’. longiros- 
tris. It is readily distinguished from L. tropicalis by its smaller asco- 
spores and pycnospores, and from /. fluens by its narrower and 
more acute ascospores and the long, slender necks of the perithecia. 


ENDOTHIA TROPICALIS Shear and Stevens sp. nov. 
SYNONYMS: : 

Diatrype gyrosa Berk. and Broome, 1875, in Jour. Linn. Soc. [London], 
v. 14, p. 124. 

Nectria gyrosa Berk. and Broome, 1877, in Jour. Linn. Soc. [London], 
V.- 15. 86: 2 

Cryphonectria gyrosa (Berk. and Broome) Sace., in Syll. Fung., v. 17, 
p. 784. 1905. 

Endothia gyrosa (Schw.) Fekl., Hohnel, 1909, in Sitzber. K. Akad. Wiss. 
[Vienna], Math. Naturw. K1., Abt. 1, Bd. 118, Heft 9, p. 1480. 

TYPE SPECIMEN.—No. 2807 S. sii S., on HIGEOO StS glandulifer, Hakeels 
Ceylon, Coll. T. Petch, August, 1913. 

PycnipIA.—Stromata corticular, pustular to pulvinate, usually gregarious or 
scattered, rarely confluent, 1 to 5 mm. in diameter, early becoming friable, 
orange chrome when fresh to sanford brown when old and weathered ; pycnidia 
consisting of numerous irregular cavities in the stroma; sporophores mostly 
simple, clavate, tapering above, 6 to 10 uw long.; pycnospores continuous, oblong 
to cylindric, very variable in size and shape, pale yellowish in mass, 3.5 to 
7 by. 1.5 to 2.5 p. 

PERITHECIA.—Stromata the same or similar to those bearing pycnidia; peri- 
thecia black, membranous, collapsing when dry, 5 to 50 or more in a stroma; 
250 to 500 w diameter, irregularly arranged in one to three layers, bearing 
slender necks which penetrate the stroma and project 0.25 to 1 mm., termi- 
nating in acute ostioles; asci oblong or subclavate, nearly sessile, 40 to 50 by 
7 mw; ascospores irregularly biseriate, subelliptical, obtuse, not constricted at 


Oe 


- ENDOTHIA PARASITICA AND RELATED SPECIES. rai 


the septum, hyaline with a gelatinous envelope, 7.5 to 10.5 by 3.5 to 5 uw, mostly 
8 to 10 by 4 to 4.5 u. : 

CULTURAL CHARACTERS.—Cultures one month old on white corn meal show 
small numerous, thickly scattered pycnidia and spore masses very similar to H. 
parasitica. The mycelium is orange buff to apricot orange. This species differs 
from JH. parasitica in culture, chiefly in the brighter color of its mycelium. 

Host.—Rotten logs and stumps of Hlaeocarpus glandulifer. 

TYPE LOCALITY.—Hakgala, Ceylon. 

GEOGRAPHICAL DISTRIBUTION.—Only known from Ceylon at present. One 
other collection of this species, No. 290 G. H. K. T. ['Thwaite], N. Eliya,’ 
Ceylon, 6,000 feet, has been examined in the Kew Herbarium. 


Through the kindness of Mr. T. Petch, of Peredeniya, the writers 
have received two large collections of this fungus. Some of the 
material was in a living condition and enabled the writers to obtain 
pure cultures for comparison with the other species of Endothia. 
This species is closely related to /’. parasitica, but is readily sepa- 
rated by its larger ascospores and larger and more variable pycno- 
spores and its nonparasitic habit. 


ENDOTHIA PARASITICA (Murr.) P. J. and H. W. And., 1912, in Phytopathology, v. 2, no. 6, p. 262 


SYNONYMS: 

Diaporthe parasitica Murrill, 1906, in Torreya, v. 6, no. 9, p. 189. 

Valsonectria parasitica Rehm, 1907, Asc. Exs., no. 1710. 

Valsonectria parasitica Rehm, 1907, in Ann. Mycol., v. 5, no. 3, p. 210. 

Endothia gyrosa var. parasitica Clint. 1912, in Science, n. s., v. 36, no. 989, 
p. 918. 

Endothia gyrosa (Schw.) Fckl. Héhnel, 1909, in Sitzber. K. Akad. Wiss. 
[Vienna], Math. Naturw. KI., Abt. 1, Bd. 118, Heft 9, p. 1480. 

TYPE SPECIMEN.—Herbarium N. Y. Bot. Garden, on Castanea dentata, Bronx 
Park, New York City, Nov. 26, 1905, Coll. W. A. Murrill. 

PYCNIDIA.—Stromata corticular, slightly erumpent to truncate conical, usually 
separate and gregarious, frequently confluent in more or less linear series 
especially in old rimose bark, 0.75 to 3 mm. in diameter by 0.5 to 2.5 mm. 
high, varying from capucine yellow when young to auburn when old and 
weathered ; pycnidia consisting of irregular, cavities in the stroma, 100 to 300 
pw in diameter ; sporophores mostly simple, subclavate, acute at the apex, usually * 
12 to 20 by 1.5 uw, more elongated filaments sometimes reaching 50 mw or more 
being frequently found among the normal sporophores; pycnospores, oblong to 
eylindric, rounded at the ends, 3 to 5 by 1.5 to 2, mostly 3.5 to 4.5 by 1.5 to 
2 w, pale yellowish in mass under the microscope; old spore tendrils coral red. 

PERITHECIA.—Stromata the same or similar to the pyenidial stromata; peri- 
thecia dark, membranous, globose to flask shaped, collapsing when dry, 5 to 50 
or sometimes more in a stroma, 300 to 400 uw in diameter, irregularly arranged 
in one to three layers and bearing slender necks projecting above the stroma, 
300 to 600 p, colored like the stroma on the outside’and terminating in acute 
ostioles ; asci oblong elliptical to subclavate, nearly sessile, 30 to 60 by 7 to 9 un, 
mostly 40 to 50 by 8 uw; ascospores irregularly biseriate, ellipsoid, obtuse, some- 
times constricted at the septum, hyaline, with a gelatinous envelope, 7 to 11 
by 3.5 to 5 uw, mostly 8 to 9 by 4 to 4.5 wu. 

CULTURAL CHARACTERS.—Cultures one month old on white corn meal have a 
white to pale orange yellow surface mycelium and produce numerous minute 


/ 


22 BULLETIN 380, U. S. DEPARTMENT OF AGRICULTURE. 


pycnidia and pale yellow spore masses. It is distinguished from its nearest 
relative, H. tropicalis, by the lighter color of the mycelium. 

Hosts.—Castanea dentata, C. sativa and cult. vars., C. pumila, Castanea mol- 
lissima from China and Castanea japonica from Japan, Quercus alba, Q. prinus, 
Q. velutina, Acer sp. 

It is also reported on Rhus typhina and Carya ovata by Anderson and 
Rankin. 

TYPE LOCALITY.—Bronx Park, New York City. 

GEOGRAPHICAL DISTRIBUTION.—Southern Maine to Ohio and southward to 
North Carolina; also Missouri, Iowa, Nebraska, British Columbia, China, 
and Japan. : 

ILLUSTRATIONS.—Murrill, 1908, in Torreya, v. 8, no. 5, p. 111, fig. 2; Petri, 
1913, in Atti R. Accad. Lincei, Rend. Cl. Sci. Fis., Mat. e Nat., s. 5, v. 22; sem. 1, 
fase. 9, p. 656, fig. 4; Heald, 19138, in Penn. Chestnut Tree Blight Com. Bul. 5, 


pl. 18; Clint. 1913, in Conn. Agr. Exp. Sta. Rpt., 1911/12, pl. 28, fig. Gon a, 


and k; P. J. and H. W. And., 19138, in Penn. Chestnut Tree Blight Com. Bul. 
4,.p. 22, fig. 2, B and D; P. J. And. and Rank., 1914, im’ N. YS Gopmelieaee: 
Exp. Sta. Bul. 347, p. 562, fig. 89. 

EXxsiccatTi.—Pycnidia and perithecia: Rehm, Asc., 1710; Wilson and Seaver, 
Ase. and Low. Fun., 3; Bart. Fun. Col., 2926; all on Castanea dentata. 


This species is closely related in its morphological characters to 


all the species of section 2 of the genus. It is most likely to be 


confused with £’. fluens, but shows constant differences, though slight, 
in size and shape of ascospores. They are predominantly broader 
and more uniform in shape, as shown by the table of measurements 
on page 35. In its active parasitic condition on Castanea it can 
always be distinguished by the presence of the mycelial “ fans” 
in the inner bark, as shown in Plate VIII. It has been confused 
with /. gyrosa through an erroneous identification of that species. 


MORPHOLOGY AND DEVELOPMENT. 
MYCELIUM. 


By far the most striking mycelial character is the production by 
_£. parasitica of yellow or buff fan-shaped formations of mycelium 
in the cambium and bark of the host. These “fans” vary from 1 
mm. to 1 cm. or more in width, and are composed of radiating 
hyphe closely pressed together to form a continuous layer. (PI. 
VIII.) So constant are these mycelial fans in their occurrence and 
so characteristic in their appearance that they furnish the most re- 
hable field character for distinguishing /’. parasitica from related 
species and may quite properly be regarded as a specific character 
when the fungus is growing in living trees. 

Anderson and Anderson (2, p. 204) first called attention to the 
fact that these fan-shaped formations of mycelium are absent from 
FE. fluens. Rankin (62, p. 248) states that when the fungus grows 
saprophytically or while the tree is dormant these fans are not pro- 
duced. Anderson and Rankin (6, p. 565) report that in inoculations 


ee ee 


igs oer Pe 


ENDOTHIA PARASITICA AND RELATED SPECIES. 23 


on Quercus alba and Q. prinus, I. parasitica produced the typical 
mycelial fans. 

Anderson (1, p. 14) considers that the occurrence of these fans 
is associated with the parasitic habit of the fungus. In his opinion 
single hyphe do not possess the power of penetrating the living cells, 
but the fungus grows on the injured and dead cells about a wound 
until a quantity of mycelium is accumulated, when it “en masse 
pushes through the living tissues of the bark.” ‘This view is also 
held by Keefer (45, p. 193), who adds that “the action of the ad- 
vancing mycelial mats seems to be physical rather than chemical, 
and the cells are mechanically broken to pieces.” 

Rankin, however, states. (62, p. 248) that “The host cells, just 
jn advance of the edges of the fan, are disintegrated and form a 
distinct gelatinous band, which can be seen with the naked eye.” 
This observation suggests to the writers that some toxic or enzymatic 
action upon the cells of the host probably occurs before the cells 
are actually invaded by the fungus hyple. Careful investigation 
of this point should go far toward determining the causes of the 
parasitism of this fungus. Whatever the cause or function of these 
fans, they are very characteristic, and the writers have found them 
invariably in diseased material of Castanea in America, as well as 
in that from China and in two specimens of /’. parasitica on Quercus. 

A similar mycelial formation, fanlike in form, is produced by 
Armillaria mellea in the bark of roots attacked by this fungus. Ex- 
cellent specimens of the Armillaria mycelial fans have been pre- 
‘sented to the writers by Prof. Wm. T. Horne, of the University of 
California. 

STROMATA. 


Under the name Melogramma gyrosum, in which they included 
specimens of both Hndothia gyrosa and F’. fluens, the Tulasnes (88, 
pp. 87-89) described the structure of Endothia in some detail. Their 
description was based chiefly on abundant local material of /. fluens 
collected on Carpinus betulus L. during several years, but they also 
used material sent by Guepin from western France, pycnidial ma- 
_ terial on chestnut from Italy, American material sent by Schweinitz 
to Brongniart and preserved in the Paris Museum, and specimens 
from Carolina sent by Berkeley. According to the Tulasnes (83, 
p. 87)? the stromata are “developed singly and emerge gradually 
as so many scattered points with fibers radiating in all directions, 
soon swell into a yellowish cone, rupture the epidermis above them, 

1 Since this manuscript was completed a very similar mycelial formation has come to 
the writers’ attention. As figured by Nowell (50), pl. 1, Rosellinia pepo, when growing 


under the bark of lime trees, forms mycelial fans resembling those of Endothia parasitica. 
2 The portions in quotations are rather free translations of the authors’ Latin. 


24 BULLETIN 380, U. S. DEPARTMENT OF AGRICULTURE. 


and put forth a very blunt apex. All are composed of a corky, 
parenchymatous, very dense, soft yellow material. The mature 
ones attain a diameter of 3 to 4 millimeters and a height of 1 to 2 
millimeters, and on the somewhat reddish, and finally rusty red to 
yellow top, they are marked by black points, the ostioles.” The 
Tulasnes observed that before the stromata reached their full size 
the pycnidial cavities were formed within them, sometimes “ widely 
open,” sometimes “narrow labyrinthine,” and that through one or 
many openings in the top of the pycnidia, the long, twisted, orange 
tendrils, composed of mucus, and innumerable thin linear spores 


were expelled. “ Perithecia are developed chiefly in stromata des- — | 


titute of spermogonia, or more often with only a few * * * they 
arise very abundantly and irregularly, some barely buried in the 
yellow corklike substance, others lower down and seemingly located 
in the bark of the host itself.” 

Although the Tulasnes included all their material under a single 


species, they noted that the pycnidial stromata of the American 


specimens (really Hndothia gyrosa) differéd considerably from the 
European (Z’. fluens). In describing the former, they say (83, p. 
88) “The American fungus is said to grow in the bark of Fagus 
and Juglans * * * asa whole it abounds with numerous, very 
small spermatia. Wherefore if it is very thinly sectioned, the pieces, 
examined with a compound microscope, show cavities just as if you 
had before your eyes the smallest Gautieria or Balsamia.” The 
Tulasnes do not try to distinguish definitely between stroma and 
mycelium, but merely state that the stromata develop within the 
mycelium. 

Ruhland (67), who was the next writer to discuss the morphology 
of a species of Endothia, defines the various portions of the fungus 
body in detail. According to his definition (p. 16) a “stroma (in 
distinction from mycelium) is the sum total of that part of the 
vegetative portion of the fungus body, which, without serving ex- 
clusively for absorption, takes part in the formation of the fruit 
body.” He sets aside Fuisting’s (36, p. 185) division of the fungus 
body into an epistroma and a hypostroma, as essentially nothing but 
the distinction of “ conidial layers” and “ perithecial stroma.” 

Ruhland divides the fungus body into an ectostroma and an ento- 
stroma. The ectostroma grows “on the upper surface of the paren- 
chyma of the bark, between it and the periderm, and is composed of 
a generally wide-lumened plectenchyma which does not possess the 
power of absorption.” This portion has the following functions: 
“The formation of the conidia, the opening and breaking off of the 
periderm, and the stimulation of the development of the entostroma.” 
The entostroma, on the other hand, according to Ruhland, “ lives in 


the parenchyma of the bark, and while young is in a high degree | 


“er ‘ 


in Pepe labore: 


Bul. 380, U. S. Dept. of Agriculture. PLATE IX. 


x 
Z 
: 


4 
‘ ENDOTHIA GYROSA. VERTICAL SECTIONS OF STROMATA ON 
BEECH. X32. 


Fia. 1.—SHOWING NUMEROUS PYCNIDIAL CAVITIES ANDTWO MATURE PERITHECIA. 
FiG. 2.—SHOWING MATURE PYCNIDIA AND PERITHECIA SIDE BY SIDE. 


Except where otherwise indicated, the photomicrographs of stromata are from unstained 
sections cut with a freezing microtome. 


Bul. 380, U. S. Dept. of Agriculture. 


PLATE X. 


Fic. 1.—ENDOTHIA FLUENS. VERTICAL SECTION OF A STROMA FROM ITALY, SHOWING 
YOUNG PERITHECIA INASINGLE LAYER. X49. FIG. 2.—ENDOTHIA GYROSA. VER- 
TICAL SECTION OF A STROMA ON BEECH, SHOWING MaTuURE PYCNIDIA WITH MATURE 
PERITHECIA BELOW THEM. X 32. FIa@. 3.—ENDOTHIA GYROSA. VERTICAL SECTION 


OF A PORTION OF A LARGE STROMA, SHOWING PERITHECIA IRREGULARLY ARRANGED 
IN SEVERAL LAYERS. 


PLATE XI. 


of Agriculture. 


. 


Bul. 380, U. S. Dept 


‘UMOIG YOIVUISTY YIM PoUTeIS UOTOeS ULRIvg 


"SEX “AINO VIOSHLINSd DNIMOHS ‘VWOULS V 4O NOILOAS IVOILYSA 'SINVINONIS VIHLOGNA 


PLATE XII. 


Bul. 380, U. S. Dept. of Agriculture. 


‘UMOIG YOIVUISIG YIM PoUTB{s MOTIONS UTTVIEg 
‘SSX “VIOBHLINVSd GNV VIGINOAd HLOG DNIMOHS ‘VWOYLS V SO NOILOSS AWVOILYSA “SINVINDNIS VIHLOGNA 


eM te 
- Ce 


ve’ Se ss An 
aot 
aS ye Sha 


OE 


ENDOTHIA PARASITICA AND RELATED SPECIES. 25 


capable of absorption, a power which it retains relatively perma- 
nently.” In addition to its absorptive function the entostroma forms 
the pseudoparenchymatic cover for the perithecial walls. 

Ruhland studied herbarium material from the Royal Botanic Mu- 
seum of Berlin and specimens from Saccardo and Cesati, and de- 
scribed it under the name of Endothia radicalis (Schw.) Fr. (£. 
fluens of the present writers). He distinguishes an ectostroma, 
shaped like a truncated cone, consisting of fine, thin-walled hyphae, 
so closely interwoven that the whole structure has a comparatively 
firm quality. Among these hyphe are crystals of calcium oxalate. 
As soon as this ectostroma breaks through the bark there is formed 
near the middle a short-lived 1-chambered pycnidium. Below this 
ectostroma (height 0.5 to 0.6 mm., diameter 0.7 to 1 mm.) the ento- 
stroma grows out as a mycelium through the upper portion of the 
bark. Ruhland says, “'The entostroma with us does not produce per- 
ithecia, but remains wholly mycelial.” He studied the perithecial 
stage in Cesati’s specimens, however, and concludes that the peri- 
thecia originate without much change in the size of the entostroma 
and-at a considerable distance, about 1 mm., below the ectostroma. 
The long necks then penetrate through the overlying entostroma 
and into the ectostroma to the base of the now functionless pycnidia. 
The upper portion of the ectostroma is then quickly killed and 
thrown off. . 

Pantanelli briefly described the stromata of the genus Endothia, 
and pointed out several morphological characters which he considers 
distinctive of /. parasitica in contrast to /’. fluens. Aside from spore 
characters, which will be discussed later, Pantanelli (60, p. 870) con- 
siders that 1’. parasitica is characterized by numerous stromata, at 
first embedded in the bark, finally free; by pycnidial cavities numer- 
ous and irregularly arranged in various planes in the stromata deep 
in the bark; pycnidial stromata 1.1 to 1.2 mm. in height and 2.1 to 2.2 
mm. in diameter; ascogenous stromata, height 1.8 to 2 mm., length 
9.5 to 3.4; width, 3 to 3.2 mm.; perithecia arranged in two or three 
layers; necks of perithecia averaging 1.25 mm., with inconspicuous 
ostioles; walls of the perithecia uncolored or light brown. 

Endothia fluens, on the other hand, has isolated stromata, chiefly 
outside the bark; pycnidia aggregated, regularly arranged in asingle 
superficial series; pycnidial stromata, height 0.4 to 0.5 mm., diameter 
1.1 to 1.3 mm.; ascogenous stromata, height 1.1 to 1.4 mm., length 
2.5 to 3.2 mm., width 1.2 mm.; perithecia arranged in a single row; 
necks of perithecia averaging 0.45 mm.; ostioles prominent; walls 
of the perithecia black. 

Anderson (1, pp. 17-24) described the development of the fructifi- 
cations of E'ndothia parasitica in detail. He studied the growth of 


26 BULLETIN 380, U. S. DEPARTMENT OF AGRICULTURE. 


the pyenidia 1 in pure culture and mage sections of perithecial stro- 
mata growing on bark. 

_According to Anderson, the pycnidium originates as a mass of 
densely intertwined hyphe, in the center of which numerous pyeno- 
spores are cut off. The crowding of these spores increases the size 
of the pyenidial cavity and crowds the outer hyphe together to form 
a sort of wall. The ostiole is formed in the top by the loosening of 
the hyphe. The stroma always starts as a loose growth of hyphe 
around the pycnidium. It does not precede, but follows the first — 
stages in the development of that organ. A fluffy growth of light- 
yellow mycelium surrounds the pycnidium and covers it over. If 
these are embedded and sectioned, they will be found to contain a 
loose tangle of undifferentiated hyphe surrounding a central pyc- 
nidium. But as soon as the cork layer is broken the stroma under- 
goes a change. There is a rapid increase in size and at the same time 
a differentiation of the cells at the tips of those branches which 
reach the exposed surface. These cells now become shorter and 
thicker, acquire heavier walls, and are densely crowded together, so 
that in cross section they appear as a pseudoparenchymatous tissue. 
The layer thus formed covers all the exposed surface of the stroma 
and also grows up around the necks of the perithecia. The stroma 
increases very rapidly in size and a mass of stromatic tissue is 
formed beneath the pycnidia, which are thus pushed out through 
the cork layer into the periphery. The primordia of the perithecia 
are formed usually in the tissues of the bark below the base of the 
original pycnidium, but at times are formed well up in the stroma. 
Usually 15 to 30 perithecia mature in a stroma. 3 

According to the writers’ observations, the Tulasnes’ description 
(88, pp. 87-89) is substantially correct so far as it goes. They, of 
course, placed pyenidial material of E'ndothia gyrosa in the same 
species with #’. fluens, but, as already noted, they observed the dif- 
ference in the structure of the stromata and aptly compared the 
pycnidial stroma of /’. gyrosa, as seen in section, to a Gautieria. 

The division of the stroma into ectostroma and entostroma made 
by Ruhland (67, p. 16) has, at least in the species of Endothia, 
no validity whatever. While it is true that pycnidia usually occur 
in the portion of the stroma first developed and perithecia often 
develop below them, this is by no means an invariable rule; and 
while stromata are developed which contain only pycnidia, other 
stromata apparently produce only perithecia or no spores whatever. 
Certainly no portion of the stroma can be distinguished which in- 
variably produces only perithecia or only pyenidia. On the con- 
trary, there is great variation in the relative position and time of 
appearance of the two types of fruiting structures. Also, while 


ENDOTHIJA PARASITICA AND RELATED SPECIES. DN 


the pycnidial cavity is sometimes small and simple, as described by 
Ruhland, it is more often large and much convoluted. (See Pls. 
XV and XVI.) : 

While the writers, of course, agree with Pantanelli (60) that 
Endothia parasitica and EF’, fluens are distinct species, many of the 
stromatic characters which he describes are so variable as to be 
unreliable. In an examination of a large number of specimens the 
writers have been unable to find any constant difference in the ar- 
rangement or structure of the pyenidial stromata. This seems to 
depend chiefly in both species on the character of the bark and the 
moisture conditions. As to size, while the stromata of /’. parasitica 
examined average somewhat larger than those of 4. fluens, the range 
of the pycnidial stromata is about the same in the two species, vary- 
ing from 0.4 to 2 mm. in height and from 0.2 to 3 mm. in length. 

The ascogenous stromata are also very variable in size. Those 
measured by the writers varied in height from 0.5 to 2 mm. in L’n- 
dothia parasitica and from 0.5 to 2.3 mm. in Z’. fluens. In width the 
perithecial stromata were from 1 to 2.5 mm. in both species, while 
there is apparently no method for determining their length, since on 
thick-barked trees continuous narrow masses of perithecial stromata 
are often formed in the crevices of the bark. These stromatal masses 
frequently extend from 5 to 10 cm., and while they are in all prob- 
ability formed by the fusion of several stromata there is no way of 
determining how far each extends. 

The arrangement of the perithecia mentioned by Pantanelli (60) 
as a specific character seems to depend on the nature of the bark of 
the host. When the bark is thin and easily ruptured the stromata 
tend to spread out so that the perithecia occur in a single layer, 
while if the bark is thick and deeply ridged the stromata are thicker 
and the perithecia occur in two or more layers. That this is not a 
specific character is clearly shown by Plate XVI. Figures 1 and 3 
of this plate show a stroma of /. parasitica and of EH’. fluens, respec- 
tively, both with three layers of perithecia, while Plate XVI, figure 2, 
and Plate X, figure 1, show stromata of both species with perithecia 
arranged in a single layer. 

Although, as already indicated, the stromata of each species are 
very variable, they are sufficiently distinct so that the native American 
species may readily be distinguished in the field. 

The stromatic characters of Hndothia gyrosa and FE. singularis 
are much more distinct than those of the other species. The stromata 
of E. gyrosa are erumpent, irregularly subglobose, with a rather 
roughened surface. They are usually from 1.5 to 2 mm. in height 
and vary from 1.5 to3 mm. in width. The stromata of 2. singularis 
are much larger than those of any other species of Endothia, being 


28 BULLETIN 380, U. S. DEPARTMENT OF AGRICULTURE. 


usually from 2 to 4 mm. in length and 3 to 5 mm. or more in diameter. 
They are decidedly erumpent, rather regular, and subglobose in out- 
line. The contents of the stromata are brick red in color and are very 
powdery when old. | 
The stromata of Endothia fluens, EF. fluens mississippiensis, and 
E’. parasitica resemble each other so closely that the species are prac- 
tically indistinguishable on this basis. All these species are char- 
acterized by partially embedded, confluent stromata which vary 
greatly in outline, depending on the nature of the bark of the host. 
As already stated, they vary from 0.4 to 2 mm. in height and from 
0.7 to 5 mm. or more in length where confluent. £. tropicalis and 
i. longirostris resemble this group in their stromatic characters. 
Pycnidia.—The pycnidia of Endothia gyrosa and EF. singularis are 
very distinctive also. The pycnidial cavities of Z. gyrosa are narrow 
and so irregularly convoluted that in a section of the stroma the 


cavities vary in width from 0.03 to 0.3 mm., averaging about 0.15 — ; 


mm. On the whole, however, they are much narrower than those 
of HL. fluens or E-. parasitica. A section of a pyenidial stroma of £. 
gyrosa shows numerous irregular, rounded to elongate chambers 


separated by narrow walls. The pycnidial cavities of /. stngularis 


(Pl. XIII) are minute, 0.03 mm. in diameter, nearly spherical, 
evenly distributed through the stroma and separated at first by com- 
paratively thick walls, which disintegrate and become powdery when 
the stroma is old. 

So far as the writers have been able to determine, the “ tendrils ” 
of pycnospores so characteristic of Endothia fluens and LF. parasitica 
are not formed in either 2. gyrosa or EL. singularis. Mature pyenidial 
stromata of /.gyrosa when placed in a moist chamber exude nu- 
merous droplets containing spores and scattered well over the surface 
of the stromata. The writers have been unable to produce any such 
change by placing the pycnidial stromata of /.stngularis in moist 
chambers, and it seems probable that the pycnospores of /. stngularis 
are set free by the breaking down of the outer walls of the stromata. 
As already mentioned, the inner partitions are friable, so the spores 
are readily scattered by the wind. 

The pycnidial cavities of Endothia fluens and E. parasitica, and 
apparently all the other species of this section of the genus, vary 
from 0.2 to 0.8 mm. or more in diameter and may consist of a 
single chamber rather regular in outline (Pl. XIV, fig. 1) or of an 
irregular cavity consisting of many chambers (Pl. XV, fig. 3) more 
or less completely separated from one another. These species differ 
from /’. gyrosa in that the pycnospores are usually discharged through 
a single opening near the top of the stroma and emerge in a single 
twisted tendril. 


eh salah cecil dias Mit hy Ma a a EI bank in 


eee ee ee 


ENDOTHIA PARASITICA AND RELATED SPECIES. 29 


Development of the stromata—The writers have not followed the 
development of the stromata in culture, but an examination of nu- 
merous sections of H'ndothia singularis, E'.gyrosa, E. fluens, and F. 
parasitica and a study of the three latter species under field condi- 
tions on various hosts shows that their development is by no means 
as uniform as indicated in Anderson’s description (1). 

According to Anderson, the pycnidium develops first, and about 
the young pycnidium the stroma is quickly formed, while the 
perithecia arise later, usually in the lower portion of the stroma. 
This may perhaps be considered the typical course of development, 
and pycnidia are often found above the perithecia, but all variations 
occur. A large stroma may be developed without a sign of a pyc- 
nidium (Pl. XV, fig. 2). In some cases there is a considerable por- 
tion of the stroma above the pyenidial cavity (Pl. XIV, fig. 2), or 
the pycnidial cavities may be surrounded by a thick stroma (PI. 
XIV, fig. 4, and Pl. XV, fig. 1). Sometimes, on the other hand, 
they are large and irregular, with little stroma (Pl. XV, fig. 3). 

The perithecia by no means uniformly arise below the pycnidia, 
but the two often occur side by side in the same stroma (Pl. IX, 
fig. 2; Pl. XIV, fig. 8; and Pl. XII). Sometimes, even, the 
perithecia are above the pycnidia (Pl. XIV, fig. 2). There seems 
to be no constant relation either as to the relative number of pyc- 
nidia or of perithecia in a single stroma. Sometimes the pycnidial 
portion is much larger (Pl. IX, fig. 1); sometimes the perithecia 
predominate (Pl. X, fig. 2); and sometimes the two portions are 
practically equal (Pl. XIT). 

A like variability apparently occurs in the sequence of the fruit- 
ing bodies. As the figures show, the pycnidia sometimes develop 
after the perithecia; the reverse order is frequent; while in several 
sections (Pl. XII, and Pl. XIV, fig. 3) the two types of fruiting 
bodies were side by side and were producing mature spores abun- 
dantly at the same time. Just what factors determine the produc- 
tion of each type of spore or prevent or delay spore production is 
unknown. It seems probable, however, that climatic influences may 
prevent the development of ascospores in many cases. The action 
of climate may be very indirect, however, for no ascospores of any 
species have yet been obtained in artificial cultures, though L'n- 
dothia fluens, L. fluens mississippiensis, EL. tropicalis, and EF’. para- 
sitica produce pycnospores abundantly on a variety of media. Cer- 
tainly, climatic factors would not account satisfactorily for the fact 
that pycnidia and perithecia are produced at the same time in ad- 
jacent stromata, or even in different parts of the same stroma. 

The size of the perithecia is rather uniform in the various species 


. (Pl. X, fig. 3, and Pls. XI and XVI), being about 0.35 mm. in diame- 


ter. They are typically globose to pyriform, but are usually more or 


30 BULLETIN 380, U. S. DEPARTMENT OF AGRICULTURE. 


less irregular on account of crowding. This pressure may be so 


great as to produce almost any shape, and such perithecia some-— 


times measure 0.5 mm. in the greatest diameter and 0.1 mm. in the 
shortest. ; 
SPORE MEASUREMENTS. 


The spore measurements recorded here were made by Miss Tiller. 
In the case of dried specimens, the spores were first soaked for three 
hours in lukewarm water and then mounted in the potassium- 
glycerine-copper medium, prepared according to the following 
formula : ; 


1 part 2 per cent potassium acetate in water. 
1 part 40 per cent glycerine in alcohol. 
Copper acetate sufficient to color. 


In the case of fresh specimens they were mounted directly in the 


same medium. The measurements were made with a Zeiss filar © 


eyepiece micrometer and a Zeiss 3 mm. 1.40 N. Ap. oil-immersion 
objective. Only approximate accuracy is claimed for these results, 
on account of the difficulty of overcoming the motion of the spores 
in a fluid medium. The results are, however, believed to be fairly 


comparable, as practically all were measured under the same condi- — 


tions and treatment, and the margin of error is presumably rather 
uniform. The differences in size of pycnospores do not appear to 
be sufficient, however, to furnish diagnostic character for most of 
the species. 

The number of measurements of ascospores of /'ndothia fluens and 
FE. parasitica is much larger than of the other species, as special 
attention was first given to these two species on account of their great 
similarity. In order to make the measurements of these species 
comparable to the others, the total number of spores of each length 
has been calculated in the percentage of the total number of spores 


measured. 
METHOD OF TABULATION. 


For better comparison, the spore measurements have been tabu- 
lated by half microns, all the spores in each specimen coming within 
0.2 of a micron of each unit or half being grouped together; e. g., 
all the spores having a length of 7.3, 7.4, 7.5, 7.6, and 7.7 microns 
are included under the heading 7.5. The tables thus show at a 
glance the number of spores of a given length per specimen. ‘The 
widths have been tabulated in the same way. ; 

For a better comparison of the shapes of the ascospores of 
Endothia parasitica and FE. fluens, the relative ratios of length to 
width in each spore have been caleulated, the width being considered 


we 


unity. The ratios of length to width were then tabulated by tenths; 


that is, all the spores in each specimen having a ratio of length to 


ENDOTHIA PARASITICA AND RELATED SPECIES. 


31 


width from 1.76 to 1.85 microns are included under 1.8. The rela- 
tive shapes of the spores in each specimen are thus clearly shown. 


TABLE I1.— Measurements of pycnospores and asci of Endothia. 


PYCNOSPORE MEASUREMENTS. 


Number per specimen having the given length or width. 


Widths (mi- 


Specimens. Lengths (microns). crons). Total. 
212.5) 3 13.5] 4 14.5} 5 |5.5] 6 |6.5| 7 Ie | alot hae Naess 
Sphaeria gyrosa Schw., Herb. 

Mipp eanise.. ts... >a nea Oe © On a: cee Re betes (ee Cr Elas 2 | 26 
S. gyrosaSchw. ,Herb.Schwaeg.|----|----| 5 | 9] 3 |----|----)----|---- aeaeN Sil ale ile 
Endothia gyrosa on beech, Al- : 

corn, Miss., No. 1796.......-- DG PAR itinere sce ah a= ans ba Gs Fas 24 
E. singularis, No. 1939 ...-.-.-. PI ho 55 | Sie Sera Age ies eee] aah) ale 14 
E. fluens, Sowerby.-..--.-.---- my pil ic kai Wo flees ea hte etcetera Bye 25 
E. fluens on chestnut, Fort 

paym@ewia sfetie te... Se ee tut nO. (le aee ep AN ciety ee rl. allt el lec 6 | 19 |. 25 
E. fluens, Lugano, Switzerland.|-...{--.-,| 1] 3] 5] 2] 1/|.-.-}.--- Siletae 12 
E. fluens mississippiensis, No. 

0 he ee Bee eel oly Sa oA cia cmielesaen fs anal out Erp AMeRE Keak = 25h 16 
Biaemeirast@is-...-2..--...--+-- (BAS oe he A (AN SR RN | eR Oiler are eerie TBA win =, 14 
Oe ee eee meets! ol ok fee a Nes el a EB 25 
BE, parasivica, No, 1696.....-.-.|.--./---- I A ag cay ae aN bag (Re i Pt) 7 ee 25 

LENGTHS OF ASCI (MICRONS). 

Number per specimen having the given length. 
Specimens. No. Total. 

25 30 35 40 45 50 55 60 
Endothia fluens on Castanea......--.--- 1702 2 8 11 LIP ROG Ee eee en fie ae 22 
yo wa ee L7Si le snes 1 14 LOY 5 SRL Ee a Bee [eee 26 
(Dbnscésel.oheteaseee ae (Ae eee oe 5 Cp ee) | ye cain eames | Weegee car | ell rel il 
Duos sod: te a eee 1 3 | eee 4 16 (ii | ht eae a ty a 26 
E. fluens on dead Castanea..........--.- Le a ie ff 16 DM ele atic ee rete See nae ene ts 26 
E. fluens on Castanea, Stresa, Italy....-- 1656 |....-- 6 16 1 1 al see am ee 25 
E. fluens on QuercuS...........--------- 711 2.| 16 a lets ee le aaa ell Aarne eettseee 25 
oe -2 a es Oe a ae ae 1927 2 10 le ae eae Pe A ek Ne fee 24 

E. fluens mississippiensis, Blue Moun- 

SSPE INI Fe cielo soln See ns = 1306) 22th 5) 14 Styl che Sees ee (ie op del ae yt 22 

E. parasitica on Castanea...--...-.-.---- PON. 2. LP) eee 1 Dep len oliet a Sis he Sta 4 

Dnt cet tb ee ee TBO Whee < ee ee ne 5 10 10 2 eee see (eke fee 26 
i. Parasivicd, Clima... ...~..----0.-+--5- PA in tae NE =) 2 el on 2 14 4 4 2S 27 
E. gyrosa on Quercus.......-...-.-..-.- 1709 1 ll A ee ere eee ere Pe ams Ie Ae ce 8 
#. syrosa on Liquidambar...:......-...|------ 19 (chy ee RS fers ees fa ete Jaeger 25 
E. singularis, Palmer Lake, Coio.......|-..--. 4 15 UCLA EEE reek en Te keys dae Li 24 
DP leeeinoseris, Ort RICO. 22... ......--|---5-- 6| 138 3 Bebe Pal te Re al iat NG cases 25 
E. longirostris, French Guiana.......-..|-----.- 6| 10 Medea tts) 2S SE ERS hs sce ae ce ly! 
Us oS ae ag eG Se ne cee (eee oe 6 5 3 2 16 

WIDTHS OF ASCI (MICRONS). 
Number per specimen having the given width. 
Specimens. Total. 
4 5 6 7 8 9 10 

LLU ee as ee ee 8 DANS. 2a Oe Ea ed ey Se 10 
[Oe RENO eb UE Ths) Be eee ee 1 8 PA IE ear eee cy Sn | gene lege ERI 11 
Ppeem aE OMS. Ib 5.2 22-5 eee e eaten le ness 2 6 Alb Ninth Sool ance hl 12 
20 0 es 1 6 Ah 5k eae wie a saa 11 
E. fluens mississippiensis.-........----.|---.----|-------- 2 6 Ag AL ae 4 8 os ee Pe 10 
Pwleneitesttis, Porto Rico... .-...5-)2.-+<. 0 2 7 Qi eee ste os aici allzia hie St 11 
BE. longirostris, French Guiana..--.....|........|--.---+-- 3 3 SRE Me bw ldo 9 
oe ES ee ee ee re 2 6 9 MEN eee 10 
eeree tia Mea eb. Joi. eee oo hk oe deh ee 1 7 eS ae 10 
Be eeeet tes AMMCTICH 42 ose le |e oe | tee |enneese |e eevee 6 AG Nei ed ae 10 


32 BULLETIN 380, U. S. DEPARTMENT OF AGRICULTURE. 
PYCNOSPORES. 


The pycnospores of all the species are oblong elliptic to cylindric 
in shape and so small as to make accurate measurement very difficult. 
Slight but apparently constant differences in their size in certain 
groups of species may, however, be traced. These differences are 
clearly shown in Table I. 

Endothia gyrosa, EF’. singularis, and EF’. longirostris have smaller 
pycnospores than the other species, the most frequent lengths being 
3 and 8.5 p. The pycnospores of /. singularis are slightly broader 
than those of /. gyrosa and LF. longirostris, being 1.5 to 2 p, as 
against 1 to 1.5 w in the last two species. 

E'ndothia fluens, F. fluens massissip piensis, and LF. parasition are 
even more closely similar in the size of their pycnospores than in that 
of their ascospores, the most frequent size being 4 by 2 yp. The 
pycnospores of /’. tropicalis are much larger and more variable in 


size and shape than those of other species. They range from 3.5 


to 7 yin length and from 1.5 to 2.5 p in width. 


ASCI. 


The writers have not attempted a study of the origin and early 
development of perithecia or asci in any of the species of Endothia. 
Work on this subject has been published by Anderson and Rankin 
(6), for Endothia parasitica, but the nuclear phenomena and origin 
and development of the ascogenous hyphe are not yet entirely clear. 
The part termed a trichogyne by these authors seems more likely to 
be the initial stage in the development of the neck of the perithecium 
than the relic of an organ of fertilization. 

The asci appear almost or quite sessile in most species, and 
though varying considerably in size and shape, as indicated in Table 
I, are usually oblong elliptic or subclavate, having a sort of inner 
membrane inclosing the ascospores and some thin granular matter 
extending to the apex of the ascus, where a slight thickening appears, 
as described and illustrated by Anderson for H'ndothia parasitica. 
A similar condition is found in various species of Pyrenomycetes and 
probably functions in some way in connection with the discharge of 
the ascospores. The asci are generally wider and slightly longer in 
FE. parasitica than in EF’. fluens and other members of section 2. The 
asci of #. gyrosa are shorter than those of any other species. /. 
tropicalis has the longest asci. The asci of none of the species show 
a very wide range of variation, as Table I also indicates. 


PARAPHYSES. 


Most students of Endothia have reported paraphyses wanting in 
this genus. Anderson (1, p. 33, fig. 32) and Anderson and Rankin 


(6, p. 579, fig. 83) report paraphyses present and figure what they 


Bul. 380, U. S. Dept. of Agriculture. PLATE XIll. 


o 


= 
B 


ENDOTHIA SINGULARIS. VERTICAL SECTION OF THE MAJOR PART OF A PYCNIDIAL 
STROMA. X 82. 


Paraffin section stained with Bismarck brown. 


Bul. 380, U. S. Dept. of Agriculture. PLATE XIV. 


ENDOTHIA FLUENS. VERTICAL SECTIONS. X49. 


Fic. 1.—SiIMPLE PYCNIDIUM WITH VERY LITTLE STROMA, FROM ITALY. FIG. 2.—STROMA 
FROM ITALY, SHOWING A PERITHECIUM ABOVE A PYCNIDIUM. FIG. 3.—STROMA FROM 
AMERICA, SHOWING A MATURE PYCNIDIUM AND PERITHECIA SIDE BY SIDE. FIG. 4.— 
STROMA, SHOWING A SINGLE PYCNIDIUM AND FUNDAMENTS OF PERITHECIA BELOW. 


Bul. 380, U. S. Dept. of Agriculture. PLATE XV. 


ENDOTHIA PARASITICA. VERTICAL SECTIONS OF STROMATA. xX 49. 


Fic. 1.—SHOWING A YOUNG, SIMPLE PYCNIDIAL CAVITY AT THE BASE. FIG. 2.—IN WHICH 
NEITHER PYCNIDIA NoR PERITHECIA HAVE BEGUN TO DEVELOP. FIG. 3.—WITH 
IRREGULAR CHAMBERED PYCNIDIA. 


All the above are about the same age—four months after inoculation. 


Bul. 380, U. S. Dept. of Agriculture. 


ENDOTHIA PARASITICA AND E. FLUENS. VERTICAL SECTIONS OF 
STROMATA. X 20. 


Fic. 1.—E. PARASITICA. SHOWING PERITHECIA ARRANGED IN SEVERAL IRREGULAR 
LAYERS. FIG. 2.—E. PARASITICA, SHOWING PERITHECIA ARRANGED IN A SINGLE 


LAYER. FIG. 3.—E. FLUENS, FROM ITALY, SHOWING PERITHECIA ARRANGED IN 
SEVERAL LAYERS. 


ENDOTHIA PARASITICA AND RELATED SPECIES. 33 


regard as an early stage of their development. They describe them 
as branching: frequently and very crooked, extending around the 
perithecium as well as upward. The writers have searched in all the 
species studied for evidence of the presence of paraphyses, but have 
never seen anything resembling ‘paraphyses as they occur in closely 
related Pyrenomycetes. If they occur, they would seem to be of an 
unusual character and difficult to recognize or else are evanescent, 
disappearing before the asci are mature. 


ASCOSPORES. 


The ascospores furnish one of the most marked characters for the 
separation of the genus into sections (Plate XVII). In section 1 
they are more or less cylindric and sometimes curved. In section 
2 they are more or less elliptic, being broadest in E'ndothia para- 
sitica and narrowest in /’, fluens and L. longirostris. The greatest 
variation in size and shape of ascospores occurs in Z. fluens, as in- 
dicated by the measurements given in Table II. Anderson (1), Clin- 
ton (18), and Heald (39) describe and figure the ascospores of £. 
parasitica as very obtuse and constricted at the septum. The writers 
have but rarely seen spores of this form. This may perhaps be due 
in part to different methods of treatment or to the age and condition 
of the material. Most of the ascospores studied by the writers have 
been mounted in the fluid medium described on page 30. Fresh 
specimens have also been studied in water mounts, but with the 
same general result. The writers are of the opinion, therefore, 
that the figures of the authors cited above do not represent the most 
common and characteristic form of ascospores of this species. (Com- 
pare Plate XVII, figs. 7 to 15.) 

43737 °—Bull. 3880—17——8 


SR eS oe ee 


BULLETIN 380, U. S. DEPARTMENT OF AGRICULTURE. 


34 


= a oe 
86 eecece cacece OL 09 82 ee ee wee ee ete ete ee ew ew ew ewww eee 9 Il 98 Z% FI J: eocase ceceeres-*seTrems) TOUeLy, 
Pome eae wer eh pent QC ease aiarg he alitee? eae eos. |e AIR AC ee ll eran TP moe OL ial 1s 86 OT ee | aaa oe ee ODL RO dct 
Oot € LY 0¢ T dit hal ee 
Oe el hoe OE “Pease ue te Bas ka Sepa ade eee PE ee at ee cele ee ee ee Seow “110 
7 a acai ea ee v Bah Oee [SR Sa ea Bera pe lees = Pcl eae fig ado pelea meal T 8 ¢ €T SI j 4 U4 Me iam Bo “"0od 
CH se eee 9 OG oN a We ee Ce ca ae TAP pl She if T ¢ 8 1) eo 9 Ee Rie GSAT |° > “Ss “uyeqUNoW enya 
eyeyuep vouviseg UO 
cn ae | (ea 3 Pe fae a ea 2 el) a Se ft ae pate = ee ho he je | [ea [eras elit *SISUSTddIssIsstu SUEN] “| 
7.1) feos ena cane ie OS em dat ae a dae te hg oe a 9 |, I LESS OL 4h eer WO et Slat jee en|mem io eee “steorpesopnesd “y 
Silane ie FT LOG el pORa ise: 1G10 ae |e ae awe ae PaO alte OM BOLO LIOF GhOer G3 Gel HE Sh ease) O56o 1 OP a8) 190% RUS) Of ac ot iat ee woe 
C98 See €1 O8GAIEGORS NEGTG. 7 Geena tee lee I € g ) jay 9€ Ol. 2S R a ERr eG Poet. *)7S5 GG 17) | Biot tele | renee eee “""" "7870, 
(1(0)] Eetaed FF ae (eg GL Tg JS) aa asa | ance ch mua Se ka | ran aes | tea i Tia T 4 G ST ST 61 9G ai IT I ASO) lil teeeees cr egete a cas 00 
SO cease [rr ss 6 LY GP) leeches |ieSneea ha Sale INR || We T \! 4 8 OT FG 8T 8T OD Sit te Seen LE9T seh . *** ATeqy 
OUI0D “Bose BOURISEO UO 
TORCH 2 * I L9 =| 08 | teak ligt aac T z T € L 9 LT 1S | &T He Weel i ie ea fae te O60he|2-"* Ajeq] “Bseljg “Bosea 
eoueyseg JO duis uo 
Oo em ie li 8 i) ae areal sored een cege ea aia baa do aia sae ee I 8 OL ANGE (Gk 8b Spal ce STAT |"O'N ‘Ol[fAeysy “e783 00p 
eounysejn peep Wo 
je la | a Pop OPM 2a eee er Soames] ace AE ae saab oe |e eee T S 9 Barre SC NPE eae LEO |""- “BA ‘Bingsyoelg 
‘goul0000 sndlenty uO 
:sueng “aT 
a a aie 8 CTLs it can PN eee fe en 4 cea eal a oe es: I iy 6 OT NPo24) OF mos eC) > || Cee aan A aaa BA ‘OT[e0T UO 
Rett aya T SI Ly | re Pee a 7 Bal tN <8 eee € 91 GG 8 £6 | ZI 9 € 4 Ml es pee eel a 7 8A (48010 
OG. a aise |e ae G Lg Oe el eee | cae oie |e lie el Cae ae A i! € 6 €1 ¥G 61 8T ai COLA irate tae SUS STis@u0;) 
Sana ba ef Sane a Som ales aga a a aie Ge SR SSS BES NST Se se he | O  Gee 0h a aes O'N “O[TfAss0[ Avy, 
eye, Uep 
—— |———_|___— ees — rele Sms ("ee Se I A |S 0 | ee a eS eoueyseg WO Suen viyjopuy 
1G Sorilee aclu oe g 45 lr | muepg| eee eS Pie a eae aoe ae eS eres T T ¢ vo $8 | ST Claralit cs. ko eee tantieq eq, 
sollg  ‘SIjeorIpel elioeydg 
(af yt eyo 9 sonal lr ae (ga ir ee i! oT LL 9 | ae a ere G 4 II II LG 4 6 OT ea ha eg ooh etme Rs Sore | ae OfOD ‘exB’]T Joule “stsue 
m -Yejn snoion® WO slie[ynsuis’ 
TIO Neel tig aie z cael a a cal Wa a I 7 g L Woe Get ASG GER aS iT Rg tae rs LOLT |p"? uuey ‘snidd5 ‘requre 


-pinbryT uo vsord3 eIqQopum 


[2101 *(SMOIOIUL) SUIPIM *(SMOIOIUT) SU43ue’T ‘ON “susta1oedg 


‘TPIM IO WYSus] UIAIS OY} ZuTAvY UeUTOeds 190d JoquInN 


‘piyjopum fo saodsoosp fo syuawmainspayy —[I ATAV, 


35 


SPECIES. 


ENDOTHIA PARASITICA AND RELATED 


*“Ayeqy ‘ouloy Jo ‘1yjouezueg Aq Uses [Vi1ejewM Uvdtiow V JO susttoeds 1 


gees > praia ol pene Fiore emilee le eC) 30 0'T o°0 L°0 eat 0's ONO Tah Gr | Gael Cogn les 12 T Fe eal tak Tae enemies aie gee ky orc irae Ae ates ee LTO OREO T Ep 
ONE ie tee aa ert cee Re |b ar rele T F T € L 0Z 1G +6 O&T cg 0€ | ieee es ad ia sae ee aie aie go aT eee ee a SIS OD [810,., 
Gielen sealer Be eae ole ance ea|S ooh) cot cue fe T € ral GS L8 tI Tie aes os (0). | tel gees “2 onic tet rer ope ate aro RCS --- py ‘U0JTEPO 
PELE lees Mle cee eel aa w T y T 6 € 9 ral ¥G Ig 81 Oe es (ND) il ae Pad CR SES a ee ORS C “-"-"BA “O[[TASTOPIOy 
CS OFT, ec art ecemte 2 PaaS eh oa aero] ee ee ma | || ae eee 8 8 €&% 66 9T 8 G SGOT Wee a Se ae ese ee eee he aan “";T[jeueweg Wooly 
10) ge eS ale cle Sele See cel aerate salt. ake dia eto I g g 6 ZS && LT 11 z TSG lee ce ee ee euryg ‘surAunjuesg ‘ds vouejseg UO 
pee te zl ame seorpseied viIqjZopuay 
Ae sae L°0 Par b Fgh bi 0's L°¢ |e Tigo Ean Oe San | east | aera | Des Ta esameciT | ere likes Be nF ee eS ee ee en ge a eer mae ee sabeibieneie ce Soares SL UULOO RIO rs 
662 i F G 6 LT &Z 68 $3 OF gg €g TS CT 9 Serie chad Casale aie tb! | cake Gaet eiecie ie a OGIO SIS “---qeedoingy “[e107, 
00T il rd T ré g yi &T GL LI GL GL II € Ghee (o> seteee Sear pale ee GOO Ta es ee ac tee oe Serie = ee HOC 
(2) Salen | See a Re V6 P 6 él 03 TI OT rat 8 ii Te ie ee ee he ae BOOT ONS Ses oo ae aa cae > ake sae ~ATRqy ‘OuL0D 
TOL | | a ee Zz g € F 9 i eT él €1 &Z Le yer Cire ace aaa eS ag GONE | Sigees Sa a pee eee ee a aa wrreooesATery “eselig 
co ay Py nA aes ssuony vIyopuq 
eae || amass c°0 6°0 eg £°S 9°¢€ q¢ Gn L°6 OTT ise Onck lie Sk OnGi | Ome Let Oe s\ oS ote (Oe SNe iS I Se as eee emt | LOO RIOT]; 
(O9G5 ~alaeee oe g c | 9 &1 02 Tg +P ¥S cg 6L CL cL L9 GS icy = eee SL bal eee gee iat aa OOS Oe “- “"TeoLIeury ‘[TeJOJ, 
TI oe eee (Saree oes Ge ae Ftd Ck OMS eer Oe, Car | Rees) Sie pa eee eee Lene [rrr oc ece ct ec eerste tees eee e eee ee nes -+--2--0q 
2, Se ir oa Vee =a Merc cal eg =A ater | ce ae ees IT S € €T ai 91 9. 9 eae a retin LOOV eg Sa a ae oe ae Bema aimee Say Sige | 5 “0g 
Bete Ness T G SG 9 L &I 81 6 L Ot rat OT if (gel Cockca a lkeie ig |) ial een emer Sage Ste ae GS a We hor ige IUISITA 
GOR = sess ra T ar Ba? arn eee eae € € L 8 FI VG GL ral or F y Od nage GOUT: Weg so oe oe eee ee cee meee Zee oss Joi > > BLU APASUEIOL) 
(CS) Soe all lee cere | aa T vA G € 8 TI cl ql 6 ral Il 9 Goa ite en | sagen COTA acess a eet eis se eae! diate aie eg SS Sta 6, OG 
RGR sles 2 T T VA g g P 9 8 CT 91 8 8 91 € (ABR a soe cies GUA So PSSST Ss a> aight ea **"*"BUITOIB) UJION 
eA eae a i | ee eer ees Eee :sueny vimJopuy 
Teds wet, i fe |S eet z PI POT > Gos RGR | 2b GOT 20 g bre eeaam ane ay capa ie "77" TANIeqsey SSer1y “stTeorpes ereeydg 
Gre ets € 6% 8°S LAG 9°C c°S Tne Ste 6G {lard 6 Gar Sia Lak 9°T 
[2101 ‘ON *suoulloedg 
“SUIPIM 04 SYISUI] JO O1YV1 UAATS OY} SUTABY UoUTOeds Jed JaqUINN 
ee Rete Ce PAISEeS 12G-RGal Cue | |en. | mite aatie Paes eee callie nate = NT OLE CaO when acs MOO Lan Pa FG Wee 1G Goel id coe | = use a0 oe | eee oa | ee | eee aie TOO MOTT 
GOP 69 ¥GG OOT Gncegl | iemh eal einen |i rs “oa Ieee ase oe saa |e es G 8 LI 6¢ 86 £0L 69 CT +3] Cl | meron Ian a Sacra Sage Oe eee had es “1810, 
Oe OS <<) Hho ek Shee es eleanor ee Ge oul hee ie ema Spar riOh Su OE lkOGeer| OG rel Co Biceg el: ge "o]tctt oc] OTT | 7727°7" “pI ‘doyepo 
FIT 6 6¢ €P Ge sail ge eal aey ecm |i chegeee sal Gmail ine cpap aes eee T € B Or 1Z G8 OT LT L jie, | sea OS2hals sam SAued | [LASHO DIO‘) 
BOS 6S: Sy OE a Sie Gs alae eee lee OA |e jk [Stole | Ole | St. | 8 4s let os res") Boot |S 1 TemEl@e” mony 
—e}e UEp voueiseD) UC 
Oot cl Gg KG eis (pel ase Sa as Pes | Re |i ee, T T € 8 8T 9G ST LT 8 SSR Sin secne <| Tepe? moe mes? STU dapa 
-unjueg ‘'ds vourjsejg uo 
SS [eee | er aS a at rate ae seoryisered “op 
Oot IZ 0¢ 8Z Li errand iia aa aR etl eta. ge erin ae alls ger bi €T 0Z cs LT 6 Gyr Ulin =, See rer: Clan ee le te ae ee oe mae =0G@i 
id Res (S| ea ame cine ats ese dread ate! aa pia fs de Ge IPG. ops Oe 0h) OB och tees | Be oalngee freee ae a Sra Bone ess ses eed) 


:SITeordo1} eIyjopug 


36 BULLETIN 380, U. S. DEPARTMENT OF AGRICULTURE. 


PHYSIOLOGY. 
CULTURAL STUDIES.! 


During the past three years the writers have had under observation 
more than 4,000 cultures of the several species of Endothia on more 
than a dozen artificial media, as well as on sterilized twigs of many 
kinds. Throughout this work the writers have been impressed with 
the uniformity of the behavior of the organism in culture and the 
certainty with which the various species could be distinguished on 
any of the media used. 

Cultures of Endothia parasitica, for sieges from specimens sent 
from China or British Columbia were absolutely indistinguishable 
from cultures made on the same medium from local material. 
Transfers made from stock cultures which had been kept on artifi- 
cial media for two years were identical with transfers from freshly 
collected material. The same remarkable constancy held for the 
other species. Cultures from material collected in different localities 
or from different hosts were identical,-not only in appearance but, so 
far as the writers were able to determine, in temperature and moisture 
relations also. As previously noted, this is in marked contrast to the 
senior writer’s experience with the species of Glomerella and it is 
believed differs from the experience of many investigators of fungi. 

No less striking is the certainty with which the several species may 
be distinguished on any medium tried. Endothia parasitica, E. 
tropicalis, and EL. fluens and its variety méssissippiensis are very 
closely related morphologically. Moreover all except EZ. parasitica 
have, as near as could be determined, much the same relation to their 
hosts. Yet each species has distinctly and readily recognized charac- 
ters on culture media. | 

It should not be imagined, however, that the differences are 
recognizable at once as clearly distinctive characters. The differences 
at first glance might readily be considered fluctuating variations. 
But the fact that the characters remain constant through hundreds 
of generations and have never varied toward one another makes 
them worthy of recognition as specific characters. 

In a previous paper (77) the writers described their results with 
cultures of E'ndothia parasitica, E. fluens, FE. fluens mississippiensis, 
and H’. gyrosa on a number of culture media. At that time the work 
of other investigators was reviewed and the methods of preparing 
the various culture media and making the cultures described. Since — 
the publication of that paper, however, cultures of two more species, — 
E. tropicalis and FE. singularis, have been secured and about 2,000 
additional cultures of the various species made. In addition to the 
culture media mentioned in the previous paper (77, p. 10), the writers — 


1The cultures described were all grown at ordinary laboratory temperatures in the d | 


winter, about 20° to 24° C. 


ENDOTHIA PARASITICA AND RELATED SPECIES. aT 


have grown the organisms on sterile twigs of many species and on 
liquid media. 

As stated above, the various species of Endothia are distinguish- 
able on any medium tested.. White corn meal in flasks has, however, 
been most used by the writers in identification work and for keeping 
stock cultures. All the species grow readily on this medium and may 
be determined with certainty within 10 days under ordinary con- 
ditions of growth. In addition, the medium is cheap, easily pre- 
pared, and does not dry out so quickly as agar media in tubes, so 
cultures may be kept alive much longer without transfers. Almost 
equally good for purposes of identification are rice and oatmeal in 
flasks, corn-meal agar, and potato agar. 

The distinguishing characteristics of the various 5 species in culture 
have been described rather fully in the previous publication and may 
be briefly summarized, as follows: 


CULTURES ON CORN-MEAL AGAR (UNSLANTED TUBES). 


Corn-meal agar proved the best agar medium for the production 
of pycnospores and showed constant differences in the cultural 
characters of the various species. The most characteristic differences 
appeared in cultures from six to eight weeks old on unslanted 
tubes. (See Pl. XXT, figs. 2 to 7.) 


Endothia gyrosa at this age showed a rather abundant, felty white myce- 
lium, flecked with capucine buff, but there were no pyenidia. In older cul- 
tures small pycnospore threads were sometimes produced. Usually before the 


cultures were 10 days old the medium was changed to a delicate lavender 


just below the mycelium, and below this to a light olive green. A few days 
later the lavender disappeared and the green deepened to olive green. 

Endothia singularis grew more slowly than any other species. Within 
three weeks, however, the mycelium covered the entire surface. It was 
smoother than #. gyrosa and nearly white, with raw umber spots where the 
mycelium touched the glass. The medium was changed to a aks hellebore 
green one-half inch below the top. 

Endothia fluens, as pointed out in the previous paper, produced an abundant 


_ deep-chrome mycelium, with usually one or two rather small pycnidial pus- 


tules. 

Endothia fluens mississippiensis produced a scant surface growth of my- 
celium, between cadmium yellow and raw sienna in color. The upper one-half 
centimeter of the agar became reddish orange. The pycnidial pustules were 
more numerous than those of £. fluens, but smaller and more scattered than 
those of Z. parasitica. 

Endothia longirostris at the end.of six weeks had a scant, webby, orange, 
aerial mycelium growing against the glass. Mycelium on the surface of the 
medium was very scant, orange to cadmium yellow in color, with scattered tiny 
. xanthine orange to orange spore masses. The color of the agar changed to 
medal bronze just beneath the mycelium, shading into orange citrine below. 
-Endothia tropicalis at the end of’ six weeks showed a thinly felted mycelium, 
white to capucine orange, with numerous small, scattered pycnidial pustules. 
The ring of mycelium against the glass was light orange yellow, as contrasted 
with white in FZ. parasitica. 


38 BULLETIN 380, U. S. DEPARTMENT OF AGRICULTURE. 


Endothia parasitica gave a scanty white growth of surface mycelium, with 
several prominent pycnidial pustules clustered near the center and of a slightly 
darker shade than the “raw sienna” of Ridgway.’ 


CULTURES ON POTATO AGAR (SLANTED TUBES). 


Potato agar was used by the Andersons (8) to distinguish E'ndo- 
thia parasitica from FE. fluens. The writers have used it extensively 
and found it a very useful medium for distinguishing the species. 
As stated in the previous paper (77, p. 11), however, unless this 
medium was very carefully prepared it varied greatly in acidity 
and probably in other respects, with resultant variations in the 
behavior of the organisms. Spore production was not so abundant 
on this medium as on many others. The preparation of this and 
other media is described in the paper cited. 


Endothia gyrosa.—This species developed rather slowly, producing a fairly 
abundant aerial growth, which was felty rather than fluffy. The color was 
white, flecked with capucine buff, and no spore masses were produced. 

Endothia singularis.—This species grew even more slowly than #. gyrosa. 
On cultures made from conidia, growth was hardly perceptible at the end 
of three days. Mycelial cultures at the end of one week showed less growth 
than #. gyrosa, but did not differ greatly from it in either color or texture. 
At the end of one month the mycelium was slightly more fluffy and decidedly 
less in amount than that of H. gyrosa. Most of the surface was a very light 
buff color, with sometimes a few spots of capucine orange to English red. 

Endothia fluwens.—Pycnospore streak cultures of this species varied some- 
what as to the amount and time of appearance of color, probably due to the 
variations in the acidity of the medium referred to above. Many tubes 
showed an orange color in one week, while others produced no orange what- 
ever. In no case did cultures of H. fluens produce the “ brassy ” metallic sur- 
face appearance so characteristic of H. parasitica. Pyecnidia were few and more 
seattered than in H#. parasitica and did not begin to appear until the third or 
fourth week. A slight amount of warbler-green color sometimes appeared in the 
medium at this age, but never so conspicuously as in HL. parasitica. 

Endothia fluens mississippicnsis.—This produced a less fluffy aerial yest 
along the spore streak than #. parasitica. After five or six days the fungus 
showed an orange color by transmitted light, and was indistinguishable in 
this respect from FH. parasitica. The character of the surface was somewhat 
different, however, and by reflected light appeared xanthine orange. When 
two weeks old this form differed still more markedly from H. parasitica in 
color, being grenadine red by transmitted light and showing no spore masses. 

FH. longirostris—At the end of one week this produced a white, fluffy growth 
scattered in small patches over the surface of the medium. ‘This later became 
rather close in texture, especially near the base of the agar slant. No spores 
were produced on this medium. 

Endothia tropicalis.—At the end of one week this showed less growth than 
FE. fluens, covering about a third of the surface of the medium, while the 
other covered nearly the entire surface. The mycelium was closely matted 
and a very pale buff (paler than any in Ridgway). At the end of one month 


1JIn the descriptions of cultures comparisons were necessarily made with cultures in 
flasks or tubes. This of course made comparison more difficult and somewhat less accurate 
than if the material had been removed from the container. 


ENDOTHIA PARASITICA AND RELATED SPECIES. 839 


HE. tropicalis covered the entire surface with a thin layer of surface mycelium, 
considerably darker in color than when one week old. 

Endothia parasitica.—At the end of three or four days at room temperature 
this showed a short, fluffy, white, aerial growth along the streak. The surface 
of the mycelium was orange by transmitted light, while by reflected light it was 
between raw sienna and antique brown at the sides. Within six days the 
mycelium, especially at the base of the agar slant, took on a peculiar metallic 
“brassy ” appearance, due apparently in part to the character of the mycelium 
and in part to the minute water drops scattered over the surface. ‘This 
portion of the culture was light orange yellow by reflected light and orange 
by transmitted light. This metallic appearance has been found to be the 
most constant and reliable distinguishing character of H. parasitica on potato 
agar. In 12 to 14 days small pyecnidial pustules appeared in the upper portion 
of the tubes, and the agar just below the mycelium became warbler-green, 
changing later to olive green. 


CULTURES ON CORN MEAL (IN 100 C. C. ERLENMEYER FLASKS). 


Endothia gyrosa.—Mycelial cultures one week old showed a growth of rather 
compact mycelium covering nearly one-half the surface of the medium. The 
mycelium was ochraceous buff near the point of inoculation, shading into 
white at the margin. There was no discoloration of the medium and no spore 

masses were seen. 

Cultures of the same kind one month old showed an abundant, rather thick 
growth, having the surface mostly covered with somewhat irregular tubercular 
masses, suggesting immature pycnidial stromata similar to those found in 
#. radicalis, but smaller and producing no spores. The surface of the culture 
was capucine buff, that of the tubercles honey yellow to Isabella. The dark 
color was apparently due in part to numerous superficial water drops. <A por- 
tion of the medium was changed to perilla purple. 

Endothia singularis.—Mycelial cultures one week old covered only one-third 
of the surface. The growth was mostly white and fluffy, with ochraceous buff 

near the center. - 

At the end of one month the growth had entirely covered the surface. The 
mycelium varied in color from cadmium orange to capucine buff, the color being 
distributed over the surface in patches. The corn meal was changed to perilla 
purple near the center. No spores were produced. 

HH. singularis was readily distinguishable from H#. gyrosa, which it resembled 
more closely in culture than any of the other species, by the rate of growth and 
the color and nature of the surface of the mycelium. JH. singularis grew more 
slowly than #H. qgyrosa, was rather brighter in color (cadmium orange), and 
the surface of the mycelium was decidedly more even, lacking the tubercular 
masses characteristic of H. gyrosa. 

Endothia fluens——Cultures at the age of one week showed a growth of 
loose, fluffy mycelium covering one-half of the surface of the medium. The 
mycelium was deep chrome to light orange yellow at the point of inoculation, 
passing through perilla purple and light pinkish lilac and fading into white at 
the margin. Occasionally the medium was changed to perilla purple near the 
center. No spores were present. 

Cultures one month old showed a compact growth, with a nearly smooth 
surface. The color ranged from light cadmium to empire yellow. The whole 
mass of the medium was perilla purple. Spore masses were rarely present at 
this stage, but shortly afterwards a few large erumpent stromata were formed, 
which extruded spores in thick masses. 


40 BULLETIN 380, U. S. DEPARTMENT OF AGRICULTURE. 


Endothia fluens mississippiensis—Cultures one week old showed an orange- 
chrome growth a little more than half covering the surface of the medium. 
The superficial growth was very similar to that of H. parasitica. There was no 
discoloration of the medium and no spore masses were found. 

The same organism one month old produced a growth with a compact, rather 
uniform surface, the superficial portion having a coarse, matted, webby appear- 
ance, which was most noticeable about the margin. The color of the mycelium 
was cadmium orange to xanthine orange, while that of the medium was un- 
changed. Spore masses were much more numerous than in #H. fluens, but 
smaller and less numerous though very similar to those of #. parasitica. 

#. longirostris.—Cultures one week old covered about one-third of the sur- 
face of the medium. The mycelium was short, fluffy, white, with only a tiny 
spot of cadmium orange near the point of inoculation. At the end of six weeks 
the entire surface was covered with a compact growth rather uniform in tex- 
ture, cadmium orange to xanthine orange in color. The surface was irregularly 
ridged, giving it a wrinkled appearance, with tiny mars orange spore masses 
irregularly scattered over the surface. This species closely resembles H. fluens 
Mississippiensis on this medium, being distinguished from that variety by the 
smaller and much less numerous spore masses. The medium is changed to 
amber brown just below the mycelium, shading into mars yellow in the lower 
portions. 

Endothia tropicalis.—At the end of one week this showed less growth than 
either H. parasitica or HE. fluens, covering about a third of the surface. The 
mycelium was matted close to the surface and was a very pale buff (paler 
than any of the buffs shown in Ridgway). No pycnidia were present. 

At the end of one month’s growth the surface was entirely covered with 
a closely felted mycelium and small, numerous, thickly scattered spore masses, 
more closely resembling those of Hndothia parasitica than any other species. 
The mycelium was orange buff to apricot orange, and orange chrome against 
the glass. The color of the medium was unchanged. . 

Endothia parasitica.—In cultures one week old the growth on corn meal 
covered about one-half of the surface of the medium. The outer margin was 
pure white, the remainder buff yellow below, with a superficial white growth 
above. A few small pustules with spore masses occurred near the point of 
inoculation. The medium was uncolored. 

Cultures one month old showed a compact growth, nearly smooth on the 
surface. The superficial mycelium was pale orange yellow. ‘The pale yellow- 
ocher spore masses were minute, very numerous, and nearly covered the sur- 
face. The medium was slightly greenish about the sides of the flask just 
beneath the mycelium. 


DISTINGUISHING CHARACTERS OF THE VARIOUS SPECIES ON CORN MEAL IN FLASKS. 


The color reactions of the various species on corn meal are very 
striking. Endothia fluens (Pl. XXI, fig. 1b), as noted above, 
changes the whole mass of the medium to perilla purple in less than 
amonth. £. gyrosa and EL’ singularis also produce this color change, 
but somewhat more slowly. . fluens mississippiensis, IL’. tropicalis, 
and £’. parasitica, on the other hand, in hundreds of cultures have 
wholly failed to produce any purple color. This furnishes an easy 
and reliable method of distinguishing /. parasitica from FE. fluens 


Bul: 380, U. S. Dept. of Agriculture. PLATE XVII. 


PHOTOMICROGRAPHS OF PYCNOSPORES AND ASCOSPORES OF 
ENDOTHIA. 


Fics. 1 TO. 6.—PYCNosporREs: 1, ENDOTHIAGYROSA; 2, E. SINGULARIS; 3, E. FLUENS; 
4, E. LONGIROSTRIS; 5, E. PARASITICA (AMERICAN); 6, E. PARASITICA (CHINESE). 
Fias. 7 TO 15.—Ascospores: 7, E. GYROSA; 8, E. SINGULARIS; 9, SPHAERIA RADICALIS, 
FROM SCHWEINITZ’S SPECIMEN IN FRIES’S HERBARIUM; 10, ENDOTHIA PSEUDORAD- 
ICALIS; 11, E. FLUENS; 12, E. FLUENS MISSISSIPPIENSIS; 13, E. LONGIROSTRIS; 
14, E. TROPICALIS; 15, E. PARASITICA. 


Bul. 380, U. S. Dept. of Agriculture. PLATE XVIII. 


ENDOTHIA PARASITICA ON PLATE CULTURES OF CORN-MEAL AGAR 4 WEEKS OLD. 
THE UPPER PLATE WAS KEPT IN TOTAL DARKNESS; THE LOWER PLATE IN THE 
DIRECT LIGHT OF A NORTH WINDOW. 


Bul. 380, U. S. Dept. of Agriculture. PLATE XIX. 


ENDOTHIA SPECIES ON WHITE CORN MEAL (10 GRAMS OF CORN 
MEAL TO 20 C. C. OF WATER). CULTURES 2 MONTHS OLD. 


Fia, 1.—ENDOTHIA GYROSA; FIG. 2.—E. SINGULARIS; FIG 3.,—E. FLUENS; FIG. 4.— 
E. FLUENS MISSISSIPPIENSIS. 


Bul. 380, U. S. Dept. of Agriculture. PLATE XX. 


—— 


ENDOTHIA SPECIES ON WHITE CORN MEAL (10 GRAMS OF CORN 
MEAL TO 20 C. C. OF WATER). CULTURES 2 MONTHS OLD. 


Fic. 1.—ENDOTHIA TROPICALIS; FIG. 2.—E. PARASITICA; FIG. 3.—E. LONGIROSTRIS, 


Bui. 380, U. S. Dept. of Agriculture. ef PLATE XxI. 


M.S.Hattley 


CULTURES OF ENDOTHIA SPECIES 


Fic. I.—a, Corn meal after 1 month’s growth of Endothia parasitica; b, corn meal after 1 
_ Month’s growth of FE fuens. 


Typical cultures on upright tubes of corn-meal agar6 weeks old, Fic. 2.—E. oyrosa 
FIG. 3.—E. singularis. Fic. 4.—H. fluens. Fic. 5.—H. fluens mississippiensis. Fic. 6—H. 
tropicalis. HIG. 7.—E. parasitica. 


. 4 
i . Pane 
& 
‘ te 
* 
7 
i 
7 . 
. ‘ 
2 ‘ 
v 
' 
1 


ENDOTHIA PARASITICA AND RELATED SPECIES. 4l 


(Pl. X XI, fig. 1) in field work when fructifications of the species 
are wanting or doubtful. 

Aside from the differences in color, the most conspicuous and 
important characteristic of these fungi in corn-meal cultures is 
found in the fructification. Clinton (18, pl. 26) has already men- 
tioned and illustrated similar differences in cultures of these organ- 
isms on agar in Petri dishes. In Hndothia parasitica the pycnidia 
and spore masses are small, numerous, thickly scattered, and em- 
bedded in the mycelium. Z. flwens, on the other hand, forms few, 
large, erumpent stromata, with spores extruding in thick, elongated 
masses. ZL’. tropicalis closely resembles /’. parasitica in number, size, 
and arrangement of pycnidia and spore masses, but differs in color 
of mycelium. L. fluens mississippiensis appears somewhat inter- 
mediate between /’. parasitica and FE’. fluens in regard to the character 
and abundance of the pycnidia and in color of the growth. These 
peculiarities have been very uniform and constant in all the cultures 
on this medium and if they could be coordinated with regular mor- 
phological differences in nature would justify the separation of this 
‘form asa species. (See Pls. XIX and XX.) 


CULTURES ON LIQUID MEDIA (IN 100 C. C. FLASKS). 


Some difficulty was experienced at first in growing the species of 
Endothia satisfactorily on a liquid medium. Abundant growth was 
obtained on a medium suggested by Dr. Mel. T. Cook. This is a 
modification of the liquid medium No. II as given by him (19). 

Cook’s liquid medium, No. IT, is prepared as follows: 


Into 500 ¢. ¢. of distilled water put 15 grams of glucose and 20 grams of 
peptone steamed at 100° C. for three-fourths hour; into another 500 c¢. ¢. of 
distilled water put 0.25 gram of dipotassium phosphate and 0.25 gram of 
magnesium sulphate, steamed for 20 minutes; filter both 500 ec. ec. into same 
receptacle, steam 10 minutes, put into flasks, about 30 ¢c. c in each flask, and 
autoclave. 


All species grew readily on this medium, “ndothia parasitica even 
producing pycnospores. At the end of one month’s growth the sev- 
eral species were readily distinglished on this medium and may be 
briefly described, as follows: 


Endothia gyrosa.—Growth scanty; did not form a continuous mat, but re- 
mained in small bunches, giving an almost flocculent appearance. The mycelium 
appeared white when removed from the culture solution, but the solution itself 
was honey yellow. 

Endothia singularis.—Growth even less abundant than #. gyrosa; formed 
small brown knots against the glass. Mycelium buff, and the medium was 
changed to honey yellow. 

Endothia fluens.—Growth somewhat more abundant and less closely matted 
than H. parasitica, entirely submerged; mycelium white; liquid unchanged in 
color. 


42 BULLETIN 380, U. S. DEPARTMENT OF AGRICULTURE. 


Endothia fluens mississippiensis.—Growth slightly less abundant than in 
E. parasitica; submerged except at the very edges; much lighter in color, being 
reddish brown. 

Endothia tropicalis—This differed markedly from either H. parasitica or 
E. fluens. The mycelium formed a thin felt over the surface, white to salmon 
orange in color, with no change in the medium. 

Endothia parasitica.—Mycelial growth very abundant, closely matted, chiefly 
submerged, but slightly arborescent in one or two small areas, which remained 
above the surface. Color, dark greenish brown. 


CULTURES ON STERILIZED TWIGS (IN TUBES). 


Early in this work it was noted that all the species of Endothia 
grew readily on sterilized chestnut twigs in test tubes. Later, tests 
were made with twigs from a number of common, woody plants. 
Twigs of Acer saccharum, Alnus rugosa, Betula papyrifera and B. 
lenta, Carpinus caroliniana, Cornus florida, Fagus grandifolia, 
Fraxinus americana, Ostrya virginiana, Populus grandidentata, 
Prunus serotina, Rhus glabra, Tilia americana, and Tsuga canadensis 
were collected in New York State early in June, placed in test tubes 


with a few cubic centimeters of distilled water and sterilized in an: 


autoclave. All the species of Endothia were tested, and all grew on 
every species of twig except Tsuga. The difficulty of completely de- 
scribing this series may readily be seen from the fact that each species 
of Endothia had a different appearance on every kind of wood. 

In general it may be stated that E’'ndothia gyrosa and FE. singularis 
grew more slowly than the other species and produced no spores, 
while all the other species produced spores on most hosts. _The 
mycelium of /’. parasitica was usually white, especially on the bark. 
EF. gyrosa and FE. singularis produced various shades of buff, while 
E. fluens, EF’. fluens mississippiensis, and EL. tropicalis developed a 
much more brightly colored mycelium, usually showing yellow or 
orange shades. 

MOISTURE RELATIONS. 


In an earlier paper (77, p. 7) the writers reported tests with 
Endothia fluens and EF’. parasitica on media containing various per- 
centages of water. It was observed that pycnospore production 
began earliest and was most abundant on the media containing the 
least moisture. 

Aside from this the writers have thus far been unable to make 
definite tests as to the moisture relations of these fungi. However, 
incidental observations in connection with the light tests (p. 43) and 
temperature tests (p. 45), as well as results of field experiments, 
particularly those at Woodstock, N. Y., make it apparent that the 
amount of available moisture is a very important factor in the 
fructification of the fungus. 


PEATE) |. 


i aie apd Vga" 


wpneemeit! Mr 


ENDOTHIA PARASITICA AND RELATED SPECIES. 43 
LIGHT RELATIONS. 


The relation of light to pycnospore production in H'ndothia para- 
sitica was first discussed by Anderson (1, p. 20). He says— 

When plate cultures are grown in total darkness on chestnut-bark agar, no 
pycnidia are developed, while on plates made at the same time and grown 
in the light, the usual rings of pycnidia appear (fig. 57). Experiments were 
also tried in which the plate was left in darkness until about half covered 
with mycelium and then brought into the light. Circles of pycnidia were 
developed, beginning with the ring which marked the outermost limit of the 
colony when removed from the dark chamber. The concentric rings which 
always appear on agar cultures are due to the alternation of night and day. 

Later, in a bulletin by Anderson and Rankin (6, p. 592), the same 
results are attributed to D. C. Babcock. 

Up to the time the above-mentioned work was published the 
writers had grown about 3,000 cultures of the several species of 
Endothia on various media in flasks and tubes. Practically all of 
these cultures had been kept in dark cases and E’ndothia parasitica 
had produced pycnidia abundantly on most of the media used. It 
seemed desirable, therefore, to determine whether wholly different 
light relations existed when the fungus was grown on plates. The 
following series of tests was accordingly made, using L’. parasitica 
only. 


LIGHT TESTS OF CULTURES ON PLATES. 


In experimenting with plate cultures in order to check up the 
results reported by Anderson and Rankin (6, p. 592) it was noted 
that there was great variation in the rate at which the cultures 
dried out. ‘There was considerable variation in this respect in dif- 
ferent plates kept side by side, apparently due to differences in the 
Petri dishes, and a marked difference between cultures kept in 
light and those kept in darkness. Since a causal relation between 
lack of moisture and abundant spore production had already been 
shown, it seemed probable that this might influence the results of 
_ the light tests in plate cultures. In fact, in a few cases the cultures 
_ kept in the light did produce spores earlier than those kept in dark- 
ness. Accordingly, in order to eliminate at least in part this fact 
which seemed to obscure the possible effect of light, a method was 
sought of equalizing the loss of moisture. In the following series 
half the plates were placed under a plain bell jar and the other half 
under a bell jar of equal size but darkened by being covered inside 
_ and out with heavy black paper, such as is used to wrap photographic 
plates. The two bell jars were then set side by side in front of a 
north window. By this means the conditions were made much more 
uniform as to temperature and moisture. There was still a slight 
difference in the rate of drying and undoubtedly at times a difference 


een . 
ite, 


4-t BULLETIN 380, U. S. DEPARTMENT OF AGRICULTURE. 


in the temperature of the hight and dark plates, but probably not |G 
sufficient to interfere seriously with the experiments. ‘ 
Series 1. On corn-meal agar plates under bell jars.—In nine days — 
there was no distinguishable difference between the plates in light and 
darkness, a few spore masses occurring near the middle of each. 
In 18 days most of the light plates showed a central ring of spore 
masses and a zone of scattered spore masses near the edge. The dark 


plates showed a few small spore masses near the center, and scat- — bs 


tered about the outer portion were the small masses of mycelium 
which usually constitute the early stages of pycnidial formation. 

In 30 days the number of spore masses had increased somewhat in 
both sets of plates, but more in the darkened plates, so that the 
number of spore masses was about equal in all the plates. The two 
sets of plates were fairly uniform as to the arrangement of the spore 
masses. Plate XVIII shows a typical example. 

Series 2. On chestnut-twig agar plates under bell jars. —After nine 
days the cultures in hght and darkness were alike. No spores had yet 
appeared in either set. 

In 30 days there were a few spore masses on nearly all of the 
plates, there being no difference between those in light and those in 
darkness either in number or distribution. 3 

Series 3. On corn-meal agar and chestnut-twig agar under bell 
jars.—in this test the plates were piled alternately, first a corn-meal 
and then a chestnut-twig agar plate, so that the two media would be 
under conditions as nearly identical as possible. The plates were 
inoculated as before and left untouched for 18 days and after that 
were examined daily. After 18 days all the corn-meal plates showed 
spore masses in practically equal numbers, while the chestnut-twig 
agar plates showed no spore masses whatever. There was no ap- 
parent difference in the growth on either medium between the plates 
in light and those in darkness. 

At the end of 25 days the cultures on chestnut-twig agar plates 
showed numerous small masses of mycelium, indicating the forma- 
tion of pycnidia. No difference was perceptible between the dark 
and light plates. 

In 28 days, from 100 to 150 of these pycnidia in each plate were 
extruding spore masses. The light plates showed in general a larger 
mass of spores than the dark plates, but this was not marked, cer- — 
tainly no greater than was accounted for by the unavoidable dif- — 
ference in radiation and the consequent difference in moisture. This 
difference in the moisture of the medium was clearly shown each ~ 
morning by the greater amount of moisture condensed on the covers — 
of the darkened Petri dishes. 

At this time (after 28 days) four corn-meal agar plates which had 
been wrapped in four layers of heavy black photographic paper and — 


ENDOTHIA PARASITICA AND RELATED SPECIES. 45 


placed on a window sill were opened and examined. In spite of the 
cold weather prevailing during this test and the consequent low tem- 
perature of the room at night, these plates contained an pyerage of 
nearly 200 well-developed spore masses. 

At the end of 35 days the chestnut-twig agar plates which had 
been kept in the light showed an average of 160 spore masses, while 
those kept in darkness showed an average of 130 spore pustules, a 
comparatively small difference in favor of the hight plates. There 
was, however, a wide difference between the various plates in each 
series, and it was impossible in most cases to distinguish cultures 
grown in the light from those grown in darkness either by the num- 
ber, size, or arrangement of the pycnidia and spore masses. 

From these experiments it is evident that pycnidia are produced 
abundantly in total darkness on chestnut-twig agar as well as on 
other favorable media. There is no perceptible difference in the 
amount of spore production or in the arrangement of pycnidia be- 
tween cultures kept in total darkness and those kept in the light 
during the day if the temperature and evaporation remain the same 
in both. Continued observation of numerous cultures grown both 
in daylight and in darkness has convinced the writers that light has 
no perceptible effect on mycelial growth either in amount, nature, or 
color production. It seems evident, therefore, that light is a neg- 
ligible factor in the growth and fructification of these fungi. 


TEMPERATURE RELATIONS. 


In an earlier paper (77, p. 9) the writers published the results of 
three series of tests made to determine the temperature relations of 
three species of Endothia. Since the publication of that paper cul- 
tures of other species and additional material of some of the species 
from widely separated localities have been secured. Four series of 
temperature tests including this new material were made on solid 
media. 

TESTS ON SOLID MEDIA. 


In these tests cultures of E'ndothia gyrosa, LF. singularis, EF. fluens, 
E. fluens mississippiensis, and L’. parasitica were tried on corn-meal 
agar in slanted tubes, oatmeal in flasks, and potato agar in slanted 
tubes. The cultures tested were from specimens chosen from the 
extremes of the known ranges of the fungi and from their different 
hosts. No difference could be detected in the various cultures of the 
same species, even in those from widely separated localities and from 
different hosts. Cultures appeared to have the same temperature 
relations whether made from spores or mycelium. The results may 
be briefly summarized as follows: 

At 41° and 39° ©. there was no growth in any species. Cultures removed 


from the incubator at the end of 11 days and kept at room temperature showed 
no growth. 


46 BULLETIN 380, U. S. DEPARTMENT OF AGRICULTURE. 


At 35° C., Endothia gyrosa, FE. singularis, and EF. parasitica showed a slight 
development within 2 days, but at the end of 11 days it was still slight and 
abnormal in appearance. LH. fluens and LH. fluens mississippiensis showed no 
growth at this temperature. 

At 31° C., Endothia gyrosa, FE. singularis, and E. parasitica appeared about 
the same as at room temperature for the first four days. At the end of six 
days these species showed somewhat less growth than at room temperature, 
while at the end of two weeks the growth was less in extent and markedly 
less freshly colored than that at room temperature. #H. flwens and H. fluens 
Mississippiensis Showed somewhat less growth than at room temperature even 
in 4 days, and markedly less at the end of 2 weeks. 

At room temperature (which at this time varied from 20° to 24° C.) the 


growth was much as described in the previous paper. Within 11 days growth 


was practically complete and in 14 days there was abundant spore production 
in Hndothia parasitica. 

At 18° and 16° C., all species showed considerably less growth than at room 
temperature, but there seems to be little difference in the comparative growth 
of the various species at these temperatures. At 13° the growth was decidedly 
less than at 16° C. but was fairly normal in appearance in all the species except 
that Endothia fluens mississippiensis failed to produce the characteristic color 
at this temperature. 

At 9° C. there was a very slight growth in all species. 

At 7°, 5°, and 2° C. there was no growth whatever. Cultures removed to 
room temperature at the end of 11 days developed normally and at about the 
same rate as in newly made cultures. 


These additional tests seemed to confirm the results already pub- 
lished (77, p. 27) ; that is, growth was best in all species at ordinary 
room temperature, about 20° to 24° C. The minimum temperature 
for all was about 9°, and all failed to grow at 7° C. The maximum 
temperature for Endothia gyrosa, EL. singularis, and EF. parasitica 
appeared to be about 35°, while the maximum for /. fluens and its 


variety ’. fluens mississippiensis was apparently about 32° C. At 


all the temperatures tried /’. singularis grew much more slowly than 
any of the other species. 

It was noted that cultures kept at 7°, 5°, and 2° C. showed no 
growth, but when removed to room temperature developed normally, 
while cultures kept at 41° and 39° C. failed to grow when removed to 
room temperature. This seemed to indicate that the fungi are more 
susceptible to heat than to cold, and such is perhaps the case. ‘There 
was, however, the additional factor of moisture involved, for while 
the agar of the cultures kept at 7° and lower was in apparently the 
same condition at the end of 11 days as when first inoculated, the 
agar of the cultures kept at 41° to 39° C. was considerably dried. 
This raised the question as to whether the drying out of the agar had 
not affected the growth of the fungi in those cultures kept above room 
temperature as much as the higher temperatures themselves. 

The same idea was suggested by the fact that several of the species 
grew for a few days at 31° C. as well as they did at room temperature, 
and then fell behind. It seemed possible that this falling off in the 


aa 


te ae 


_ 3 


a 


ENDOTHIA PARASITICA AND RELATED SPECIES. 47 


rate of growth might be due, at least partly, to more rapid drying of 
the agar at 31° C., or possibly to the more rapid development 
of some toxin, as was suggested by Balls (7) to explain a similar 
observation on the “soreshin” fungus. These observations threw 
doubt upon the accuracy of the writers’ previous conclusions, and 
made it seem possible that the optimum temperature of the species 
of Endothia might be well above room temperature. This could only 
be determined accurately by some method which would control tem- 
perature without altering the supply of moisture. Some months 
after the above tests were concluded it was discovered that the various 
species of Endothia would grow readily on several liquid media. 
Consequently, several series of tests on liquid media were run parallel 
to those described above, except that the tests were continued for 
only four days. Experiment showed that at the higher temperatures 
the medium became considerably reduced by evaporation if left for 
a longer period. 
TESTS ON LIQUID MEDIA. 


In the series of tests on liquid media, all the species of which cul- 
tures had been obtained were grown on Cook’s medium (see p. 41) 
both in tubes and in flasks, using ten tubes and six flasks at each 
temperature. The cultures of H'ndothia gyrosa and FE. singularis 
were made with bits of mycelium from pure cultures. The other 
species were grown from conidia and the cultures were kept for two 
days at room temperature, in order to allow the conidia to germinate 
before being placed in the temperatures to be tested. 

The following temperatures were used for making the tests: 40°, 
37.5°, 35°, 29°, and 27°, and room temperature which was fairly 


constant at about 22°, 17°, 12°, 9°, 7°, 3°, and 2° C. There was some 


variation in the temperature of the incubators and refrigerators 
used, but in most cases they did not vary more than 1 degree above 
or below the temperature indicated. At 40° there were occasional 
traces of growth, especially in Endothia parasitica, but this may have 
occurred when the incubator dropped to 39° C. There is no regular 
and continued growth at this temperature. 

At 37.5° C. there was perceptible growth in all the species. This 
is in striking contrast to the results on solid media, as no species 
grew at a temperature above 35° C. on solid media. 

At 35° C. Endothia parasitica showed practically the same amount 
of growth as at 27° and 29° C. for the first three days, but fell behind 
after that. LE. fluens showed less growth at 35° than at the lower 
temperatures. These two species were the only ones tested at 35° C. 

At 27° and 29° C. growth was markedly more abundant than at 
37.5°, and in most of the species was more abundant than at room 
temperature. In HLndothia gyrosa and EF. fluens mississip piensis the 


48 BULLETIN 380, U. S. DEPARTMENT OF AGRICULTURE. 


growth at 27° C. was apparently equal to that at room temperature. | | 


At 22° C. (room temperature) all species developed much more rap- 


idly than at the lower temperatures. At 17°, 12°, and 9° C. there | 
was progressively less and less growth. At 7° C. and lower there 5 


was no growth whatever. 

While these tests are not wholly satisfactory and must be regarded 
only as approximations, they are of some interest. Below 7° C. there 
is no growth in any species. 


It is evident that there is a considerable range of temperature, 
from below 20° to well above 30° C., within which the species of En- | 
dothia grow readily. Within this range there may be a definite ~ 
optimum for each species, but this has not yet been determined. For — 


Endothia parasitica the optimum appears to be at 27° C. or above, 
and the same may be true of the other species. 


At 40° C. or above no growth occurs. There is considerable evi- ~ 
dence, however, that L'ndothia fluens is less resistant to the higher ~ 


temperatures than either 2’. parasitica or EL’. gyrosa. After several 
of the tests the flasks were kept at room temperature for some days. 


It was found that all developed normally except those which had 2 


been kept at 40° and 37.5° C. These developed more slowly than 
those which had been kept at lower temperatures. It was particu- 
larly noticeable also that 2’. parasitica and FE’. gyrosa developed prac- 
tically as well after being kept at 40° as at 37.5° C., while cultures 
of LZ’. fluens which had been in 37.5° developed fairly well; but if 
kept at 40° for three days they entirely failed to develop. 


DISTRIBUTION OF THE SPECIES OF ENDOTHIA. 


During the past two years the writers have studied over 600 speci- 
mens of Endothia from various parts of the world. The greater 
number of these specimens have naturally come from the United 
States. The maps (figs. 14+) show the known ranges of the various 
species in this country. Each dot on a map represents a locality 
from which the species has been collected. Frequently, of course, 
many specimens have come from a single locality; hence the number 
of dots by no means represents the number of collections. 

In the case of Endothia parasitica, the dark portion represents 
the area over which the blight is practically continuous; that is, 
practically all the stands of chestnut are either diseased or dead. 
The dots represent known isolated infections and the solid line marks 
the botanical limit of the chestnut. 


Endothia gyrosa is known only from the United States, but has a: 


range in this country wider than that of any other species. As 
shown in figure 1, it has been found as far north as central Michigan, 
east to Connecticut, on the Pacific coast near San Francisco, and on 


; 
{ 
| 
a 
; 


ENDOTHIA PARASITICA AND RELATED SPECIES. 49 


the Gulf of Mexico. There is, however, a very great difference in 
the abundance of this species at different points. In the southeastern 
United States—that is, the region south of central Indiana and 
southern Virginia and east of central Arkansas and Louisiana—this 
species occurs in great abundance wherever its hosts are found. 
Broken branch stubs and exposed roots of Liquidambar, Fagus, 
and Quercus are covered with fructifications of this fungus. This is 
especially true of roots exposed by erosion or excavation which have 
suffered mechanical injury through the tramping of men or cattle. 
_ Farther north in Maryland, New Jersey, and Connecticut only an 
occasional specimen is found. Three days’ search in southern Con- 


Fic. 1.—Outline map of the United States, showing the distribution of Endothia gyrosa. 


necticut, for example, yielded only two specimens, both on Liquidam- 
bar, showing pycnidia only. 

Endothia singularis is known at present only on oaks in the dry 
foothill regions of Colorado and New Mexico. Bethel, in a letter, 
states that it is very abundant in certain localities in Colorado. 

Endothia fluens has long been known to occur in both Europe and 
America. Recently, through the kindness of Dr. Y. Kozai, director 
of the Central Agricultural Experiment Station, Nishigahara, Tokio, 
Japan, the writers received four specimens of fungi on chestnut. 
One of these, collected by S. Tsuruta on October 14, 1914, in the 
Province of Totomi, was the pycnidial stage of an Endothia, which 
when cultured proved to be /. fluens. Ascospore material of this 
species has since been collected by Meyer at Nikko, Japan, on the 
bark of Pasania sp. 

43737°—Bull. 380—17-——4 


50 BULLETIN 380, U. S. DEPARTMENT OF AGRICULTURE. 


Endothia fluens, while common to Europe, Asia, and America, has 
a much more limited range in the United States than /.gyrosa. It 
is fairly common on Castanea and Quercus from southern Pennsyl- 
vania and Ohio to northern Mississippi and Alabama. In south- 
eastern Pennsylvania it has been found so far only on roots of 
Quercus, and in northern Mississippi and Alabama only on Castanea 
dentata. 

E'ndothia fluens mississip piensis was first sent to the writers from 
Corinth, Miss., by Mr. T. E. Snyder, of the Bureau of Entomology, 
and has since been collected in only four other localities, three near 
the northeastern corner of Mississippi and one in central Kentucky. 


Fic. 2.—Outline map of the United States, showing the distribution of Hndothia fluens. 


As both Endothia gyrosa and F. fluens were collected in this 
country nearly a century ago by Schweinitz, it seems altogether 
probable that they are indigenous species which may have already 
reached the limits of their natural ranges in this country. 

While the maps (figs. 1-4) do not give by any means every locality 
where Endothia is to be found and specimens are likely to be col- 
lected at many points outside the present known range, the writers 
feel justified in assuming that these maps represent the limits of 
the territory where Endothia gyrosa and LE’. fluens may commonly be 
found. This is especially true in the eastern portion, where the field 
has been rather thoroughly worked. It is unlikely, for instance, 
that /. fluens occurs abundantly in southern Alabama and Georgia, 
where £’. gyrosa was found so commonly. Southeastern Pennsyl- 
vania must be somewhere near the northern limit for /. fluens, for 
the writers’ four collections in that region are the result of six days’ 


ae. eT 


1 taal ain 


<a ll heal 


: 
: 
| 
: 
| 


ENDOTHIA PARASITICA AND RELATED SPECIES. 51 


search. At the northeastern limit of /. gyrosa, Clinton (15, p. 79) 
found only a single specimen after two years’ search, and the writers 
have looked for it in all the other New England States without find- 
ing a single specimen. The report of /. gyrosa from Massachusetts 
by Hitchcock (42, p. 63) has already been shown to be a probable 
‘error in identification. 


FACTORS INFLUENCING DISTRIBUTION. 
HOST RELATIONS. 


Just what determines the present ranges of the species can not, of 
course, be positively decided, but some relation to certain external 
factors may be traced. Neither species has the same distribution as 


Fic. 3.—Outline map of the United States, showing the distribution of Hndothia fluens 
mississippiensis and EH. singularis. The dots indicate collections of EL. fluens mississippt- 
 ensis and crosses indicate collections of LW. singularis. 


its hosts. Quercus and Fagus are both abundant farther north than 
Endothia gyrosa has yet been found, while Quercus is abundant 
north and south of the known range of /’. fluens. It may be worthy 
of note, however, that /’. gyrosa extends north as far as Liquidambar 
is found. Perhaps more significant is the relation of the range of 
E. fluens to that of the chestnut. As will be seen from a comparison 
of the maps (figs. 2-4), #’. fluens is not found abundantly at any point 
outside the natural range of the chestnut. Especially interesting is 
the fact that the southeastern limits of #. fluens and Castanea den- 
tata are practically coincident, for in this region H/'ndothia fluens 
was found only on Castanea, never on Quercus. This suggests the 


possibility that Castanea may be the original and favorite host of 
Endothia fluens. 


52 BULLETIN 380, U. S. DEPARTMENT OF AGRICULTURE. 


SOIL CONDITIONS. 


Greater opportunity for infection seems to be an important factor 
in the greater abundance of Endothia in the South. By far the most 
favorable places of infection, especially for Hndothia gyrosa, are 
bruised or broken but still living roots. Soil, cultural, and climatic 
conditions combine to make these many times more abundant in 
the Southern States than elsewhere. The more sandy and easily 
eroded soil, usually without turf, subject throughout the winter to 
the action of wind and rain, leaves innumerable oak roots exposed, 
which are readily injured by vehicles and the tramping of horses and 
cattle, leaving wounds suitable for the entrance of Endothia. In the 


Fic. 4.—Map of the United States, showing the distribution of Hndothia parasitica in 
December, 1915. The solid portion shows the area in which H. parasitica is generally 
present. The dots indicate scattered infections. The heavy line shows the limits of 
the range of Castanea dentata. 


- North, the more rocky soil, frequently covered with sod, protected 


through much of the winter by snow, makes exposed roots much less ~ 


common, and the roots so exposed are rather less subject to mechani- 
cal injury. In the writer’s experience the most favorable localities 
for collecting /. gyrosa are the unfenced public squares of Southern 
towns, where partial grading, erosion, and constant traffic have left 
hundreds of oak roots exposed, and the pastures of southwestern In- 
diana, where the roots of Fagus are often found injured by cattle. 


COMPETITION AMONG FUNGI. 


The writers’ extensive field studies and observations have con- 
vinced them that competition among fungi must be considered as a 


* saw 


i 


iia ee 


Qo te 
a oP 


ENDOTHIA PARASITICA AND RELATED SPECIES. 58 


factor in determining their distribution. As already stated, while 
Endothia fluens occurs on Quercus, it has been found toward the 
southwestern limit of its range (northern Mississippi and Alabama) 
only on Castanea, and in Tennessee the writers have sixteen collec- 
tions of this species on Castanea and only three on Quercus. In 
this same region, /’. gyrosa is everywhere abundant on Quercus. In 
numerous inoculations with /. gyrosa and £. fluens on oak it has 
been found that /. gyrosa is more generally successful than #. fluens. 
Moreover, /. gyrosa occurs abundantly on Liquidambar and Fagus 
in this region, thus providing more numerous sources of infection 
for this species than for /’. fluens. It seems highly probable, there- 
fore, that /. gyrosa, with its greater affinity for oak and greater 
opportunity for infection,*‘may occupy the available oak roots to 
the exclusion of Z’. fluens, even though climatic conditions are favor- 
able for the growth of the latter species. Castanea rarely serves as 
a host for #’. gyrosa,; consequently, on this host /’. fluens meets with 
little competition and is very abundant. 

In the northeastern limit of its range, Endothia fluens has been 
found only on oak roots. Whether it grows naturally on chestnut 
in this region can not well be determined, since practically all the 
chestnut trees here are dead or badly diseased with FE. parasitica. 
£. gyrosa is rare in this region, but #. fluens here evidently comes 
into competition with Valsa frustum-coni (Schw.) Curtis, which is 
common on exposed roots of various species of Quercus. 


CLIMATE. 


Since none of the species of Endothia in America extends to the 
limits of its host species, climate probably has an important part in 
determining their present ranges. 

In this connection it is of interest to compare several life zone and 
_ climatic maps which have been published with the range maps of 
the various species of Endothia. The map entitled “ Life zones of 
the United States,” by C. Hart Merriam (50, pl. 14), is based largely . 
on a study of animal life. Merriam deduces from his studies the 
conclusion that the northward distribution of animals and plants is 
determined by the total quantity of heat and their southern dis- 
tribution by the mean temperature of the hottest part of the year. 
The life zones which he outlines show, however, a striking relation 
with the known ranges of Endothia in America. With the exception 
of a single locality for Z'ndothia gyrosa in Michigan, all the known 
localities for 2. gyrosa and L. fluens fall within the Upper Austral 
and Lower Austral zones. All the known localities for Z. fluens and 
all the region where Z. gyrosa has been found abundantly fall within 
the humid divisions of these zones. The northeastern limits of the 
Upper Austral coincide very closely with those of Z. gyrosa; its 


54 BULLETIN 380, U. S. DEPARTMENT OF AGRICULTURE. 


limits in Pennsylvania include the northern localities known for 
i. fluens, while the southern limits of this zone coincide closely with 
the southern limit of /. fluens. 

The Livingstons (47) have published maps based on temperature 
summations and temperature efficiencies, as well as maps in which 
isoclimatic lines of temperature are combined with precipitation 
indices and evaporation indices for the mean frostless season. 

While no very definite relations between these maps and the ranges 
of Endothia can be traced it is noteworthy that the localities where 
E'ndothia gyrosa is known to be abundant are all south of or near 
the 600 line of temperature efficiency, and only one collection of 
FE’. gyrosa has been made north of the 400 line. JL. singularis, on the 
other hand, has thus far been found only north of the 400 line. 

Zon’s map (86) of vegetal regions of the United States is based on 
periods of growth and rest. The regions where Hndothia gyrosa 
and #’. fluens are abundant are all south of the line which marks the 
northern limit of seven months’ vegetation. In fact this coincides 
very closely with the northern limit of /. fluens, and no specimen of 
LE’. gyrosa showing ascospores has been found farther north. 

The relations pointed out above strongly suggest the possibility of 
some causal connection between climatic conditions and the present 
ranges of Endothia species, but just what factors may limit the 
spread of the species is not yet determined. The temperature tests 
recorded on pages 45 to 48 throw little light on this problem, for the 
maximum and minimum temperatures are about the same in the vari- 
ous species. “ndothia fluens seems to be less resistant to the effects of 
high temperature (40° C.), but it is difficult to see that this fact alone 
has any direct bearing on the question of distribution. 


DISCOVERY OF ENDOTHIA PARASITICA IN CHINA. 


For eight years after its discovery in the New York Zoological 
Park in the summer of 1904, Endothia parasitica was known only 
from eastern North America. During this time two quite different 
opinions as to the origin of the fungus were advanced. Some in- 
vestigators maintained that /. parasitica was an indigenous fungus 
(15); others that it had been imported from some foreign coun- 
try, probably oriental (51, 52.) In the fall of 1912, however, pyc- 
nospore material was sent from Agassiz, B. C., by H. F. Giissow, 
Dominion Botanist of Canada. Cultures made from this material 
were identical with ZH. parasitica, and a series of inoculations on 
Castanea dentata produced typical cankers. Later, a large quantity 
of material collected at Agassiz by Dr. James R. Weir was received, 
which included a few ascospores. These proved to be typical 
EL’. parasitica. 


| 


ENDOTHIA PARASITICA AND RELATED SPECIES. 55 


A brief description of the identification of other specimens of 
EF. parasitica from Agassiz is given by Faull and Graham (29). 
These writers report that in the material sent them in the summer 
of 1913 there were no perithecia, but that the pycospores were typical 
FE. parasitica and the characteristic mycelial fans were present in 
the bark. Cultures of the fungus proved it to be identical with 
EF. parasitica. They also state (p. 203) that the chestnuts grown 
at Agassiz “are of oriental, European, and American origin. The 
stock was purchased from nursery firms located in New Jersey, 
Ohio, and California. One of these at least ‘was a heavy importer 
of oriental trees and shrubs’.” They suggest that it “is significant 
that a connection with the Orient exists.” 

In support of this view, the statement of Mr. Sharpe, who had 
charge of planting the nut orchard at Agassiz, may be given. Dr. 
Weir visited Mr. Sharpe at Salmon Arm, B. C., and Mr. Sharpe 
stated definitely to him that he would be willing to furnish affidavit 
to the effect that in the main or entirely the chestnut trees in the 
nut orchard were originally imported from the Orient; in fact, a 
part of the trees, according to Mr. Sharpe, undoubtedly came from 
Japan or China and were shipped to Agassiz in the original wrap- 
pings, which consisted of the peculiar mats and casings of those 
countries. 

In a letter accompanying the specimens from British Columbia 

Giissow states that “these trees may be regarded as absolutely iso- 
lated. There is no other chestnut tree anywhere round it for 500 
miles and more.” It seems highly probable therefore that Z. para- 
sitica was carried to this locality on nursery stock, perhaps as sug- 
gested by Faull and Graham and by Weir by importation from the 
Orient. 
i The following spring (1913) Mr. Frank N. Meyer, agricultural 
_ explorer, discovered this fungus in Chihli Province, China, under 
such conditions as could leave no doubt that it is indigenous there. 
The account of this discovery and its corroboration in this country 
was published by Fairchild (27), and also by the writers (76). 

As outlined by Fairchild (27), Meyer first found the diseased 
_ chestnuts near Santunying, a small town 13 days journey by cart from 
 arailroad, northeast of Peking in Chihli Province, between Tsunhua- 
_ tcho and Yehol. 

A small specimen of diseased chestnut bark from this region was 
 inclosed in a letter from Mr. Meyer which was received by Mr. Fair- 
child on June 28, 19138. From this specimen, which showed only 
_ pycnospores, cultures were obtained, which proved it to be true /. 
parasitica. On July 23 more Chinese specimens were received from 
_ the same locality, as well as from Scha Ho in the same Province. 
_ These included a large canker on a chestnut branch about 6 cm. in 


56 BULLETIN 380, U. S. DEPARTMENT OF AGRICULTURE. 


diameter, which agreed in every respect with cankers produred on 
varieties of Japanese chestnuts in this country (Pl. XXII). 

Other specimens in this collection showed well-developed perithecia 
and ascospores. The ascospore measurements made at the time, as 
well as the cultures of the Chinese fungus and the inoculation experi- 
ments on (. dentata, are described in the previous paper by the 
writers (76, p. 296). 

Shortly after this first series of inoculations was made subcul- 
tures of the Chinese material were sent to several investigators who 
had been studying the chestnut-bark disease, in order that the 
Endothia from China might be tested as soon as possible under 
American conditions by inoculations at various points throughout 
the known range of the disease. 

A series of inoculations was made by Prof. J. Franklin Collins at 
Martic Forge, Pa., on July 14, 1913, using American and grafted 
Paragon and grafted Japanese chestnut trees. Another series of 
inoculations, 56 in number, was made at the same locality Septem- 
ber 10, 1913, by Dr. Caroline Rumbold on grafted Paragon chest- 
nuts. Twenty inoculations were made on native chestnuts at Ander- 
son, Pa., October 2, 1913, by Dr. F. D. Heald and R. A. Studhalter. 
Inoculations with the Chinese Endothia were made at Leesburg, Va., 
on both Castanea dentata and C. pumila by G. Flippo Gravatt and 
J. T. Rogers, August 16, 1913. 

All these investigators made duplicate inoculations with American 
material, and all agreed that the Chinese fungus was identical in its 
effects on the host with the American chestnut-blight fungus. Dur- 
ing the season of 1914 numerous inoculations with material from 
China were made by the writers at various points in New Hamp- | 
shire, Massachusetts, Connecticut, New York, Delaware, and Mary- 
land, while others have been made in Rhode Island by Prof. Collins 
with the same results. 


ADDITIONAL CHINESE SPECIMENS. 


Since the publication of the previous paper (76) additional speci- 
mens of /. parasitica from China have been received from Meyer; 
one collected at Changli, Chihli Province, China, October 13, 1918, 
by Mrs. Mary S. Clemens; a quantity of material collected by Meyer 
himself in the village of Tachingko, near Taianfu, Shantung, China, 
March 21, 1914; and another collected by him at Yatyeko, Shensi, 
China, September 2, 1914. A few cankers have also been sent by 
Meyer, collected by him at Shihbonshan, near Hangchow, Chekiang 
Province, China, June 26, 1915. The label on this specimen bears 
the further comment, “very destructive in this locality.” Cultures 


have been made from all these specimens and have invariably proved 


to be identical with cultures of £. parasitica found in this country. 


Bul. 380, U. S. Dept. of Agriculture. PLATE XXIl. 


AN OLD CANKER CAUSED BY ENDOTHIA PARASITICA ON A BRANCH OF CASTANEA 
MOLLISSIMA. 


Collected by Frank N. Meyer, May 381, 1913, near Santunying, Chihli Province, China. 


Bul. 380, U. S. Dept. of Agriculture. PLATE XXIll. 


Fia. 1.—JAPANESE CHESTNUT AT NIKKO, JAPAN, FROM WHICH THE CHESTNUT 
BLIGHT FUNGUS (ENDOTHIA PARASITICA) WAS COLLECTED BY F. N. MEYER, ON 
SEPTEMBER 17, 1915. 


Fic. 2.—Two BRANCHES OF A JAPANESE CHESTNUT. THE LARGER (TO THE LEFT) 
Was BROUGHT TO THIS COUNTRY BY F. N. MEYER, AND FROM IT ENDOTHIA 
PARASITICA WAS ISOLATED. 


ENDOTHIA PARASITICA AND RELATED SPECIES. 57 


As Tachingko is 300 miles south of Changli, where /. parasitica was 
first collected by Meyer, and Yatyeko is 500 miles west of Tachingko, 
it seems highly probable from the collections that Z’. parasitica is 
widely distributed in China (fig. 5). 

Meyer, writing from Hangchow, July 1, 1915, refers as follows to 
the condition of the chestnuts in that locality: 

Well, I have a few interesting discoveries to report. First, there are many 
specimens of Castanea mollissima scattered at the bases and on the lower 
slopes of the hills around here, and these chestnuts are seriously attacked 
by the bark fungus, and in my estimation are going to succumb to it these 
coming years. The chinquapins (Castanea spp.), however, which are very 
abundant on the higher and more sterile hill slopes, seem to be immune; 


Fic. 5.—Outline map of China and Japan, showing the localities in which Hndothia 
parasitica has been found. 


at least I did not see any evidences of damage or even of attacks. This 
brings another interesting point to my mind. I was told in Nanking that 
various missionaries at Kuling, the great summer resort in central China 
for missionaries, were cutting down their chestnuts, as the tops were all 
dying, due to borers working underneath the bark. 


Meyer has since stated to the writers that he believes the de- 
struction of the chestnut at Kuling is due to Endothia parasitica 
rather than to borers. 


In the writers’ earlier publication the following statement was 
made (76, p. 297): 


The Chinese organism has thus been shown to be practically identical with 
the American in all its morphological and physiological characters and in 
the production of the typical chestnut blight and the pycnidial fructifications 


4 


58 BULLETIN 380, U. S. DEPARTMENT OF AGRICULTURE. 


of the fungus. There is apparently but one other requirement that could be* 


made according to the strictest pathological canons to perfect the proof in 
this case, and that is the production of typical ascospores of H. parasitica 
on the lesions produced by the inoculations. : 

The last requirement has now been fulfilled. Specimens collected 
February 15, 1915, from inoculations made September 20, 1913, on 
chestnuts in Virginia, near Point of Rocks, Md., with Chinese ma- 
terial, show perithecial stromata with typical ascospores of /. par- 
asitica, thus completing the evidence. 


DISCOVERY OF ENDOTHIA PARASITICA IN JAPAN. 


More than two years after his original discovery of Hndothia 
parasitica in China (June 8, 1913), Meyer also discovered the fungus 


in Japan. A brief account of his discovery has already been pub- 


lished by the writers (78). It may be sufficient here to state that fol- 
lowing the discovery of E'ndothia parasitica in China the writers 
endeavored by correspondence to obtain the fungus from Japan. 
While not successful in obtaining Hndothia parasitica, the writers 
did receive several specimens of fungi, including species of Endothia 
on species of Castanea. These, together with several specimens of 
fungi found on chestnut nursery stock from Japan, make it clear 
that there are in that country several Pyrenomycetes other than 
Endothia parasitica more or less parasitic on Castanea. 

Meyer first discovered the chestnut-blight fungus in Japan at 
Nikko, September 17, 1915, on wild trees of Castanea crenata Sieb. 
and Zuce. A photograph of the trees from which he collected speci- 
mens of H'ndothia parasitica is shown in Plate XXIII, figure 1, and 
a branch from which the diseased material brought to the United 
Sates was taken is shown in Plate X XIII, figure 2. 

Shortly after Meyer’s arrival in Washington in December, 1915, 
the specimens collected at Nikko were turned over to the writers for 
study. Examination at once showed cankers and mycelial fans 
typical of E’'ndothia parasitica. 'The material also contained typical 
pycnospores and ascospores of the fungus. Cultures made from 
single ascospores on various culture media proved to be identical 
with those of Lndothia parasitica found in this country and in China, 
thus establishing beyond question the identity of the fungus. 

Meyer’s observations as to the resistance of the Japanese chestnuts 
to this disease are of great interest. He states that the trees vary 
considerably as regards their power of resistance, but that in general 
the Japanese chestnut is even more resistant to Endothia parasitica 
than is the Chinese chestnut (Castanea mollissima). 

As announced in the same publication (78), Endothia parasitica 
was collected by Dr. Gentaro Yamada at Morioka, northern Japan. 
These specimens, which show typical cankers as well as ascospores of 
the fungus, were received by the writers on January 8, 1916. 


ry. 


_ 


ENDOTHIA PARASITICA AND RELATED SPECIES. 59 
PRESENT DISTRIBUTION OF ENDOTHIA PARASITICA IN AMERICA. 


The present range of E/'ndothia parasitica in America, as shown by 
the map (fig. 4), is probably merely the extent to which it has been 
able to spread in the time since it was first introduced. 

Whether Endothia parasitica was introduced inte one locality or 
several is uncertain, but the studies of Heald (40, 41) and others have 
shown clearly that the spores of Z’. parasitica are carried by the wind, 
by insects and birds, and on nursery stock, which would account 
for its wide distribution and for its occurrence in isolated localities, 
long distances away from the main body of the disease. It also makes 
it seem probable that the fungus will continue to spread with some 
rapidity. | 

Certainly, there is no evidence that any factor, climatic or other- 
wise, is likely to prevent the spread of this fungus into the large area 
of chestnut south of its present range. On the contrary, the duplicate 
inoculations made by the writers show clearly that the fungus grows 
more rapidly at the southern limit of its present range than farther 
north, where it is much more common. The longer growing season 
in the South is also no doubt an important factor. 

In this connection, it may be noted that Ké6ppen (46), in his map 
of the vegetation regions of the earth, places the portion of China 
where “L'ndothea parasitica has been found indigenous in the same 
climatic region as that portion of the United States where it is now 
doing such destructive work. He designates this region as the 
“ Hickory ” division of the mesotherms. 


HOST RELATIONS OF THE SPECIES OF ENDOTHIA. 


ENDOTHIA GYROSA. 


Endothia qgyrosa occurs commonly on Liquidambar, Fagus, and 
Quercus, occasionally on Castanea, and has been found on Vitis in 
Alabama, but the writers were unable to obtain fresh material from 
this host. 

While Fagus and Quercus are, of course, closely related, it seems 
remarkable that a fungus should be abundant on hosts so different 
as Liquidambar and Quercus, yet so rare on any other host as to be 
only once reported. It seemed possible, indeed, that the fungus on 
Liquidambar, while morphologically and culturally identical with 
that on the various other hosts, might prove to be physiologically dif- 
ferent. In order to obtain more definite information on this point, 
several series of cross inoculations were made. 

It had been observed that Hndothia gyrosa was found most fre- 
quently on the cut or broken ends of branches or on exposed, bruised, 
or broken roots. In making inoculations, therefore, a small branch, 


60 BULLETIN 380, U. S. DEPARTMENT OF AGRICULTURE. 


1 inch or less in diameter, was cut off about 6 inches from the 
main trunk. Mycelium from corn meal in flasks was placed on the © 
cut end of the stub and covered with wet cotton, over which oiled 
paper was tied. In about two weeks the paper and cotton were re- 
moved. In all cases. branches similar to those inoculated were cut 
as checks. 


TABLE IIil.—Jnoculations with Endothia gyrosa. 


Source of fungus and Host inocu- Number | Number 


of inocu- | success- Remarks. 
date. lated. lations. ful. 
Fagus: 
May 8, 1913........ Castanea..:... 6 3 fae first observed on Oct. 16. 
May 29, 1913....... Fagust.* 35:>.- 3 3 | Pycnospores first observed on Aug. 29 for 
two and on Oct. 10 for the third. 
Sept. 15, 1913....... Liquidambar . 5 2| No growth until the spring of 1914; pyc- 
' nidia scattered and small on Oct. 13. 
Dorreenees ences Quercus® <2 acc. 4 2 | No growth until spring; well developed on 
Oct. 13, 1914. 
Apr. hE, Spe see ESGUS.. oc. 2-8 4 0 
ges Sd ee Quercus. -s2=<. 4 0 
Do ale Sain age ee Castanea ...... 4 2 he peo: stromata well developed on Oct. 
13, 1914. 
May 23, P14 Sc Se lesee = 7 ae. 4 4 Do. 
sat cue ei tates pa eerwos! 4 0 
Do 3 BER in RMR Quercus !... 4 0 
DO. cea nee Fagus: ..-- d= 4 3 Do. 
Quercus: 
May 29:°1912. . £23 $1) 20. do. =. <2 3 3 | Pycnospores first observed on Aug. 29, 1913. 
I caseos ck ae Liquidambar A 2 | Very slight indications of growth on Aug. : 
Fit ons a few pycnidia with 4 on 
c 
Sept. Ae, Ok eee eee tC eee oe 8 0 
v4 OP ket Me Castanea .....-. S| 2 — well-developed pycnidia on Oct. 13, 
Apr. “2 1914S... Wapisee.o. 3230 4 0 
Ss ciete Se Quercus!..... 4 0 
Do Gre scale = Sea Castanea ...... 4 4 eon, pycnidial stromata on Oct. 
May 23; 19142. tks ee G0c3culen 4 4 | Abundant well-developed pycnidial stro- 
mata on Oct. 13, 1914. 
DO. ssa eameeset 4 0 
Doyen ae Quercus !. 4 0 
Dein. casacsoeee Papus.. scicwk 4 3 
Castanea: 
May 20. 10Rss assy cele WO. an 208 3 3 | Pycnospores first observed on Aug. 29, 1913. 
Dose | nee eee Liquidambar . 3 3 | Slight indications of pyenidial formation on 
Aug. 29, 1913; pyenospores on all on Nov. 
Ue: 1913. 
ADToa told aoeee ae BFagus-ettecs 5 4 0 
Dac gees Bee? ob Quercus!..... 4 1 ins welleveloped pycnidial stromata 
on Oc 
Dasswsaseiit. Castanea...... 4 3 | Scattered, fairly well-developed pycnidia 
on Oct. oa 1914. 
May 23 104. co eee donceccen. 4 4 ete well-developed pycnidia on Oct. 
13, 1914. 
Dot. Pee ee Liquidambar 4 0 
DO ei case Quercus !..... 4 0 
Liquidambar: 
May 29, 1913....... MAgae os wens e 3 0 
Dee tas 24 eee Liquidambar . 3 3 | Pyenospores first observed on Aug. 29. 
Sept. 15, 1913......- eh eae ae 8 5 | No evidence of growth until the Spring: of 
1914; pycnidia few and small on Oct. i5. 
WG. ic Seca ee Castanea ...... 6 2| No growth until the spring of 1914; pyc- 
x nidia small on Oct. 13. 
FEY ee. Quercus....... 6 0 
Apr. 2, th Peete ree GGUS: tek oe 4 0 
WOrrete nes ven Quercus ! + 0 
Dor: ces. -¢e Castanea .....- 4 0 
May 23,1984: 503). -cck d0.<162533 4 0 
DOs oo cadteien Gs Liquidambar 4 4 | Abundant pycnidia on Oct. 13, 1914. 
DO see ee ee Quercus!..... 4 0 
Davee. gore ieees Fagus..c2. 5% 4 0 


1 The species used in this case was Quercus prinus, which proved to be an exceedingly unfavorable host 
for Endothia gyrosa. 


_ ENDOTHIA PARASITICA AND RELATED SPECIES. 61 


Inoculations with ELndothia gyrosa were also made on numerous 
hosts from which it had never been reported. Six or more inocu- 
lations were made on each host, in the manner described above, ex- 
cept that a part of each series was left unwrapped. The following 
inoculations showed no growth whatever: Those made in Virginia, 
April 4, 1914, on Cornus florida, Fraxinus americana, Juglans cinerea, 
llex opaca, Soe atrns variifolium; in Maryland, April 17 and 22, 
1914, on Carya glabra, Cornus florida, Liriodendron tulipifera, Nyssa 
sylvatica, Sassafras varufolium, and Quercus alba; and in New 
York, July 11, 1914, on Betula alba, Prunus serotina, Populus trem- 
uloides, Rhus glabra, Salix sp., and Sassafras variifolium. On Acer 
pennsylvanicum and Carya two out of the six inoculations developed 
a few stromata. These were found only on the tissue injured by 
the cut and there was no evidence of parasitism. 

On Castanea, Fagus, Quercus, and Liquidambar, however, a branch 
inoculated as described above dies back rather faster than the checks. 
- This would indicate, as suggested by Clinton (18, p. 419), that 
F.. gyrosa is a weak parasite; that is, that it is able to invade injured 
and dying tissue. 

It is evident from Table III that E'ndothia gyrosa coming from 
any of the four hosts named will, under favorable circumstances, 
grow on any of the others. Several other interesting facts are 
brought out by the table. Inoculations made with material from 
Liquidambar grew in general more rapidly on Liquidambar than 
on any of the other hosts. In many cases, material from, Liquidam- 
bar failed to grow on Castanea, Fagus, and Quercus, and even when 
inoculations were successful growth was somewhat slower and pyc- 
nidial production less abundant. 
| On the other hand, inoculations from Fagus, Quercus, and 
_ Castanea usually grew less rapidly on Liquidambar than on any 
_ of the other three hosts. This is, of course, what would be expected 
from the systematic relationships of the host species, and while the 
inoculations made are too few to permit any definite conclusions 
they are nevertheless suggestive. As shown by Table III, Quercus 
prinus proved a very unfavorable host for Hndothia gyrosa. 

In all cases inoculations made in the fall (Sept. 15) failed 
to show any growth until the following spring. This corresponds 
with the results in inoculations of E'ndothia parasitica, but it is, of 
course, impossible to determine whether this failure to grow is due 
to the dormant condition of the host or to unfavorable weather con- 
ditions. Perhaps correlated with the results just noted are the 
unusually poor results obtained from inoculations made in the early 
spring. It will be noted that inoculations made on April 2, 1914, 
were in general much less successful than those made on May 23, 
1914, in exactly the same locality and in many cases on the same 
hosts. 


62 BULLETIN 380, U. S. DEPARTMENT OF AGRICULTURE. 
ENDOTHIA SINGULARIS. 


The material of E'ndothia singularis distributed by Sydow as Calo- 
pactis singularis was on Quercus gambellit Nutt. The writers have 
seen abundant material on this species as well as specimens on Q. 
utahensis (A. DC.) Rydb., Q. leptophylla Rydb., and Q. nitescens 
Rydb. Specimens on the latter two hosts were sent by Bethel, who, 
in a letter, reports finding this species also on Q. pungens Liebm. — 

All of these species except Quercus leptophylla are chaparral- 
forming shrubs growing at an elevation of 4,000 feet or more. 


There is at present no evidence that the fungus is parasitic on any — 


of the species. 

Inoculations with the mycelium of /'ndothia singularis were made 
on Fagus and on Quercus alba, Q. velutina, Q. rubra, and Q. palustris, 
as well as on Q. dicifolia on Overlook Mountain in the Catskills. 
No growth has, however, been noted in any case. 


ENDOTHIA FLUENS. 


When these investigations were commenced, the writers thought 
that the Endothia found in Europe might be the same as Hndothia 
parasitica found in America. Inoculations were accordingly made 
in Maryland during October, 1912, with cultures from material col- 
lected on the chestnut by the senior writer at Stresa, Italy, and 
Etrembieres, Switzerland, using material of /'. fluens sent by P. J. 
Anderson from Pennsylvania; also material of that species and of 
FE. parasitica collected in Virginia as checks. In this case, as in all 
others where no special mention is made of the method, inoculations 
were made by cutting through the bark to the wood with a sharp 
knife. The inoculating material was then inserted with a freshly cut 
twig and the wound tied up either with cord or rubber bands. If 
cord was used it was cut away within two to four weeks. The rub- 
ber bands became loosened by exposure to the weather within about 
the same time. 

Inoculations were made with all the above material on sprouts of 
Castanea dentata and Quercus prinus. The results are summarized 
in Table IV. 


TABLE IV.—IJnoculations of Endothia in Maryland in October, 1912. 


Number | Number 
Fungus. Host inoculated. ofinocu- | showing 
lations. | growth. 


Endothia parasiticaias. soestess ere eee en eeee are Castanea dentata............ " 28 


DOS. anc s be teseb esas te Lee Reed een Quercus prinus:.:-.22 aera 0 
E. fluens 
MUrOpean.. A500 ak: See a Nee he ee Castanea dentata............ ; 14 14 4 
AMOPriCany 4. sWas Reiss ae pas a eeeie ee = oe me eee | Eee (0 Co PRE IES Gos. 26 23 
DO eso. See a: Ea ae Quercus prinus,.<.2- 2.2. see 12 9 


eS a a 


Te a 


a 
4 


ENDOTHIA PARASITICA AND RELATED SPECIES. 63 


The inoculations were examined every 10 days until December 1 
and. monthly thereafter throughout the winter. There was no per- 
ceptible growth until the last of April, when several of the inocula- 
tions of Endothia parasitica showed slight sunken areas. By May 
20 all inoculations checked as showing growth (last column of table) 
showed the slight yellowish elevations of the bark which indicate 
the beginnings of pycnidia. On August 30 all the inoculations of 
E. parasitica checked asyshowing growth had spread rapidly and 
attacked the living tissues of the host, producing typical cankers with 
mycelial fans and abundant pycnidia. 

No signs of growth were noted in the inoculations of E'ndothia 
fluens until about the middle of May, 1913, when most of them 
showed signs of pycnidium formation. By August 30 all those 
marked as showing growth had produced characteristic pycnidia 
with spores, which when cultured proved to be typical /’. fluens. In 
no case, however, did this fungus spread for any appreciable distance 
beyond the injured portion or show signs of active parasitism. These 
results agree with those given by Anderson and Anderson (2, p. 206) 
with American material of /’. flwens, and have since been fully con- 
firmed by further observation. 

During the summer of 1914 about 1,100 inoculations of E'ndothia 
fluens from both European and American sources and of £. fluens 
mississippiensis were made on Castanea sprouts. In no cage was 
there any evidence of active parasitism, as in /’. parasitica. 

Although E’ndothia fluens has been found in Europe on a con- 
siderable number of deciduous host plants (as recorded on p. 18), 
the writers have thus far failed to find it in this country on any 


except Castanea and Quercus. It seemed possible that the European 


strain of the fungus might be somewhat more plurivorous' in its 
habits than the American. In order to throw some light on this 
point, the following inoculations were made: 


On March 31, 1914, 10 inoculations were made, half of European and half 
of American material, at Francis, Md., on the following hosts: Alnus rugosa, 


Betula nigra, Carpinus caroliniana, Carya glabra, Fagus grandifolia, Lirio- 


dendron tulipifera, and Liquidambar styracifiua. Pycnidia appeared only on 
Carya glabra and Carpinus caroliniana. Of the inoculations which actually 


_ produced pycnidia, four on Carpinus and three on Carya, one of each was the 


Huropean strain. 

On April 22 inoculations were made with American material of EH. fluens at 
Kensington, Md., on Acer rubrum, Carya glabra, Cornus florida, Fagus grandi- 
folia, Prunus serotina, Quercus prinus, Sassafras variifolium, Vaccinium sp., 


—17his term is proposed to apply to fungi occurring on two or more hosts or substrata 
and may be applied to all fungi except true parasites. It is derived from plus (plur-), 


_ more, and vorare, to devour. Compare omnivorous already in use for fungi. 


The term pleioxonous might be derived from De Bary’s proposed word pleioxony and 
applied to true parasites having the power to invade more than one species of host plant, 
and the term plurivorous restricted to nonparasitic organisms, 


64 BULLETIN 380, U. S. DEPARTMENT OF AGRICULTURE. 


and Vitis sp. Of these, Acer rubrum and Carya glabra gave numerous small — 


pycnidia. 

On July 10 the following hosts were inoculated at Woodstock, N. Y., with 
E. fluens from Europe: Acer rubrum, A. pennsylvanicum, Carya ovata, Corylus 
americana, Fraxinus americana, Hamamnelis virginiana, Kalmia latifolia, Popu- 
lus grandidentata, Prunus serotina, Rhus glabra, Salix sp., Sassafras variifo- 
lium, and Syringa vulgaris. Each host was inoculated in six or seven places, 
but all failed to develop except two inoculations on Acer pennsylwanicum and 
one on Corylus americana. 


The results cited above are so largely negative that they prove very _ 
little except that the European strain shows no special affinity for 


these hosts in America. 


ENDOTHIA FLUENS MISSISSIPPIENSIS. 
Only five collections of L'ndothia fluens mississippiensis have thus 
far been made, three on Castanea dentata and two on Quercus sp. 
From the results of the inoculations its host relations appear very 
similar to those of /. fluens. The results are, shown in Table V. 


TABLE V.—IJnoculations with Endothia fluens mississippiensis on Castanea and 


Quercus. 
Number | Number | 
Source of culture. Host inoculated. Date. of inocu- | showing 
lations. | pycnidia. 
Castamensiies 222 che hee es ae Castanedaigs.2...£0k fete Jan. 20,1912 8 
DO a Sa eee os eeto seed oc aa eee eee roo Pea OE EYEE eee May 8, 1913 4 
IDO. 032.255 PoS ee ee eee doj2i JIT See doi.tau 4 
Gass hie Fano a cee Cota epee. ee “Quercus prinus ..),52<0)~2 See rs | eee 9 
DO: sa 2S SSh. ERE eet ee Castamenic.. Aik. Aeeseee Apr. 18,1914 12 1 
Quercus) s.262 002 ease ee ve 6 osOOD copes de ange cee eee eee do2s 38 12 1 


The inoculations of January 20, 1912, showed no signs of growth 
until early in May, when the first signs of pycnidium formation were 
observed. The inoculations with Hndothia fluens mississippiensis 


made May 8, 1913, showed within three weeks discolored areas near ~ 


the cut which were larger than those about the check cuts. On July 


25, 1913, all of the inoculations of 1’. fluens mississippiensis marked Ei 


“successful” showed the beginnings of pycnidium formation. By 
August 30, 1913, they were producing pycnospores, which when cul- 
tured proved to be £. fluens MASSISSip PLENsis. 

Inoculations were made in April, 1914, for the purpose of com- 
paring the material collected on oak oan that collected on chest- 
nut. No difference was detected, and there was no indication of active 


parasitism. This form behaved in this respect exactly as did the £. 


fluens from Virginia both on Castanea dentata and Quercus prinus. 


A series of inoculations parallel to that made with /. fluens was 


made with EZ. fluens mississippiensis. The same hosts were used, 


and in most cases the dates and places of the inoculation were the | 
same. The results of all that showed any growth are given in ~ 


Table VI. 


ENDOTHIA PARASITICA AND RELATED SPECIES. 65 


TaBLE VI.—IJnoculations with Endothia fluens mississippiensis on Acer and 
Carya. 


; Number | Number 
Location. Host. ofinocu- | showing 
| | lations. | pycnidia. 


ye naw nino ine owes bee seas ACEP PUDTUM sac. oak ae ae 6 3 
ok te a ee ¥o} COR VMS IAMEAR Se sthe fora n wes 6 2 
a i Se alae ene te SPD High SN ia At ae 6 1 
a Aiéér rari. «- 5.20 te 1 if 
te a Carya slabranec se cce acess. 2 2 


As in L'ndothia jfluens the growth was confined to the injured tis- 
sues, and there was no evidence of parasitism. 


ENDOTHIA TROPICALIS. 


The material of Hndothia tropicalis from which the writers se- 
cured their cultures, was collected by T. Petch in Ceylon. As the 
species of Endothia in the Northern Hemisphere are chiefly on 
members of the Fagacez, Petch’s statements with regard to hosts 
are of considerable interest. In a letter of March 6, 1914, he writes: 

We have no Fagacex native in the island. We have introduced various 
species of Quercus and Castanea, but subsequent to Thwaite’s discovery of 
this fungus. I do not think there can be any doubt that the fungus is native 
toxCcyion —*. * * 

Of the speciments now sent * * * those in the packet * * * are 
from a tree which was producing shoots from the base. This tree is Hlaeocar- 
pus glandulifer Mast. From the bark and habit, I believe that all my “ finds” 
of Hndothia have been on this species. 

In the accounts of the American chestnut disease, I notice that several 
authors speak of ‘“ cankers,” and give their rate of growth. I never see 
“cankers” (Krebs) on the Ceylon trees. The bark appears to die regu- 
larly and smoothly from above downward, and is quite unbroken except for 
the minute cracks through which the stromata emerge. 

Inoculations—As already noted, ascospores of EYndothia tropi- 
calis resemble those of /. parasitica even more closely than do those 
of E. fluens. This fact, together with its similarity on culture media 
and its oriental origin, led the writers to fear possible parasitic 
tendencies. 

Inoculation experiments were accordingly made only on the chest- 
nut and under carefully guarded conditions. In all, about 30 
inoculations were made on 2-inch chestnut sprouts, using the methods: 
described for other species. 

Of 25 inoculations made in May and June, practically all had de- 
veloped a few pycnidial stromata by October 20. These stromata 
were a somewhat brighter orange than those of /’. fluens or I’. fluens 
“mississippiensis, and the spores when cultured produced typical /. 
tropicalis. In no case, however, was there any evidence of parasitism. 


' 43737°—Bull. 3880—17——5 


66 BULLETIN 380, U.S. DEPARTMENT OF AGRICULTURE. 
ENDOTHIA PARASITICA ON HOSTS OTHER THAN CASTANEA. | 


The first collection of Endothia parasitica on a host other than 


Castanea of which the writers have any knowledge is that made by _ 


J. Franklin Collins at Martic Forge, Pa., June 30, 1909. As an- | 
nounced by Dr. Metcalf at the Boston (December, 1909) meeting 
of the American Phytopathological Society, the specimen consisted — 
of a small dead branch of Quercus velutina with several spore — 
tendrils typical of £. parasitica. This material, which consisted of | 


a terminal branch with leaves still retained, was at once sent to the 
laboratory at Washington, and cultures obtained from it were sub- | 


sequently used in making numerous inoculations on Castanea dentata ~ 
on Long Island, N. Y., in July, 1909. On November 17 of the same — 
year, Metcalf reported that the inoculations were entirely successful — 
and had produced typical lesions, thus establishing without question — 
the identity of the fungus. | | 
Fulton (37, p. 53) reports 2’. parasitica on the dead bark of Quer- 


cus alba and Quercus velutina, but found no evidence that the fungus 


_ produces in any sense a disease of such trees. Clinton (18, p. 428) 

mentions cultures from three different species of Quercus and (p. | 

376) reports specimens on Quercus alba, Q. rubra, and Q. velutina. | 
Anderson and Babcock, as quoted by Anderson and Rankin (6, p 


564), found Lndothia parasitica on Quercus velutina, Q. alba, Q.— ‘ 


prinus, Rhus typhina, Acer rubrum, and Carya ovata, but it seemed | 
parasitic only on Quercus alba. They made inoculations with mate- 
rials isolated from Castanea on Quercus prinus, Q. velutina, Q. alba, 
Q. coccinea, Rhus typhina, Acer rubrum, Liriodendron tulipifera, and ~| 
Carya ovata. Two trees of Rhus were girdled and killed by the — 


growth of the fungus. On Quercus alba the fungus seemed slightly © 


parasitic, but none of the trees were killed. The fungus grew and — 
produced spore horns on the wounded tissue near the point of inocu- 
lation on all the hosts except Acer and Liriodendron. 

Rankin (62, p. 238) also made inoculations with Endothia para- — 
sitica from Castanea on Quercus prinus, Q. rubra, Q. alba, and Q. — 
coccinea. He found that the mycelium advanced into the living © 


tissues for a short distance in a few cases, but that in no case were ~ | 
typical cankers formed. Pyecnidia were produced abundantly on the | 


injured tissues of all the hosts. , q 
During the course of this work only four specimens of Endothia | 


parasitica on hosts other than Castanea have come to the writers. ~ 


One was on chestnut oak (Quercus prinus) collected by F. W. Besley, 1 
at Towson, Md., December 26, 1911; one from Quercus velutina, at 
Germantown, Pa as well as one aR white oak (Quercus alba), at 
Kennett Square, Pa., were collected by S. B. Detwiler; and one 4 
from dead maple, Acer sp., at Florence, Mass., by Roy G. Pierce. ~ 


ENDOTHIA PARASITICA AND RELATED SPECIES. 67 


The specimen collected by Besley on Quercus prinus showed the fan- 
shaped mats of mycelium typical of /£. parasitica on Castanea spe- 
cies. The fungus had apparently girdled the tree. The specimen on 
Quercus alba, collected by Detwiler, was similar to one on Quercus 
| prinus in appearance and came from a dead tree which had appar- 
ently been killed by the growth of the fungus. The specimens on 
Acer sp. and on Quercus alba were received in the spring of 1914, 
and cultures isolated from them were used in making inoculations 
for the purpose of determining whether the fungus had either lost 
or gained in virulence by passing through other hosts. 


INOCULATION EXPERIMENTS. 


_ The cultures secured from Acer and Quercus, together with one 
made from Castanea at about the same time, were inoculated into 
three separate sprouts of Acer rubrum, Oustanea dentata, and Quer- 
cus prinus. The sprouts chosen were of nearly the same size, 2 
inches in diameter, and similarly situated, and each was inoculated 
in five places, with two check cuts above. The inoculations were 
made the usual way on March 31, 1914, and were examined at least 
once a month during the summer. 
None of the inoculations on Quercus produced any growth what- 
ever. On Acer the inoculations with the culture from Quercus all 
failed to develop; one of the inoculations with the culture from 
Acer showed a few pycnidia, while four of the inoculations with 
material from the chestnut developed a few pycnidia. On Castanea 
the three series of inoculations were almost identical, every inocula- 
_ tion producing a typical canker. 
Of course, these inoculations are too few to be conclusive, but it 
is evident that there was no decrease in virulence on the chestnut 
in passing through Acer or Quercus and that no particular affinity. 
for either Acer or Quercus was gained. On the maple, in fact, the 
culture direct from chestnut produced the most growth. 
In addition to those listed above, numerous inoculations were made 
‘in order to determine whether H'ndothia parasitica had any parasitic 
tendencies on other deciduous hosts. 
These inoculations were all made during the spring of 1914 by 
‘the usual method of cutting well through the bark and inserting 
mycelium and spores from a pure culture, usually on corn meal. 
‘The wounds were then wet, some bound with wet cotton, others with 
paraffin paper, and about half were left unwrapped. 
_ Seven or more.inoculations were made on April 4 in Maryland on 
Alnus rugosa, Betula eg Carpmnus caroliniana, Fagus grandifolia, 


68 BULLETIN 380, U. S. DEPARTMENT OF AGRICULTURE. 


22 in this locality on Acer rubrum, Carya glabra, Cornus florida, — 
Fagus grandifolia, Liriodendron tulipifera, Quercus prinus, Sas- 
safras variifolium, Vaccinium sp., and Vitis sp. without success. — 
On April 18, the following hosts were inoculated in Virginia: Acer 
rubrum, Betula nigra, Benzoin aestivale, Carpinus caroliniana, Carya 
glabra, Cornus florida, Fagus grandifolia, Liriodendron tulipifera, 
Prunus serotina, Quercus alba, Ulmus americana, and Vitis sp. 
Each host was inoculated in from four to six places. Of these, 
pycnidia were produced only on Acer rubrum, Carpinus, and Lirio- 
dendron. A similar series was made on the same hosts in the same 
place on May 27. Inoculations on one tree of Quercus alba showed — 
undoubted evidence of parasitism and is described below. 

On July 9 and 11 from five to fourteen inoculations were made 
on each of the following hosts at Woodstock, N. Y.: Acer rubrum, 
Betula alba, Carya ovata, Fagus grandifolia, Fraxinus americana, 
Hamamelis virginiana, Juglans cinerea, Kalmia latifolia, Nyssa syl- 
vatica, Ostrya virginiana, Populus grandidentata, Prunus serotina, 
Rhus typhina, Quercus rubra, Salix sp., Sambucus canadensis, and 
Sassafras variifolium. Pycnidia appeared on Acer rubrum and 
Ostrya only. The fungus made considerable growth on two plants 
of Rhus typhina, partly girdling branches one-half inch in diameter 


and producing distinct fans. The fans were, however, much smaller . : 


than those usually found in Castanea. Inoculations were made at | 
Avon, Conn., July 15, on Acer saccharum, Betula alba, Carya glabra, 
Cornus florida, and Ostrya virginiana. Pyecnidia developed only 
on Ostrya. The successful inoculations with Endothia parasitica 
are shown in Table VII. 


Taste VII.—Successful inoculations in 1914 with Endothia parasitica on hosts 
other than Castanea. 


. Number | Number 
Locality. Date. Host. ofinocu-| success- 
lations. ful.! 


Vareiniais s/c set ate eee Apr, 18.| Acer rubrum’. 2..\., 2.222 ee eee 9 ie 
I) OS ee a icrelers eae oeiaye etal epeve doze Carpinus caroliniana . << 1.2.7 0e eee 6 2 
DOE in wink peewee eRe ee do.....| Liriodendron tulipifera........ 2. -2ccuseee 6 1 
PQS oie eres ence Seater ee May 27 | Quercusalbalcl toe. cose seen ee eee 4 4 

Nem Mork :)\5. ca9-5). antes July iL | Acer pennsylyanicum.....-..2--.-2).peeeeem 14 4 
DOr coe Geta nie eine store toe eee d0s..a: Ostrya virginiana. /.2..2..-2 eee 6 2 

Connecticut 2 oSateee- ater ae July Scie cee DO wis « censicee's s\sicien te alee eee 15 4 


1 Inoculations producing pycnidia are classed as successful. 


It must be noted that while pycnidia were produced in the cases 
listed as successful, there was no indication of parasitism, nor did 
the growth extend beyond the tissue injured by the cut except in 
Quercus and Rhus. 

Out of about 400 inoculations with Hndothia parasitica on hosts | 
other than Castanea, about 70 of which were made on different ; | 


ENDOTHIA PARASITICA AND RELATED SPECIES. 69 


- species of Quercus, chiefly @. prinus and @. alba, only one case has 
- been noted in which the fungus assumed a typically parasitic role. 
The data in this case may be summed up as follows: Four inocula- 
tions were made May 27, 1914, on a small tree of Quercus alba. This 
tree was suppressed, and although when cut down it showed about 
30 annual rings it was only 16 feet high and about 2 inches in diam- 
eter. It was in a moist, shady locality close beside a stream, and in 
spite of its small size was apparently healthy. The inoculations 
were made in the usual way from a culture of /. parasitica on corn 
meal. On August 1 it was noted that all four inoculations were pro- 
ducing pycnidia, and in at least one case typical fans had been 
developed. On October 15 all four cankers had more than half 
girdled the seedling. No observations were made during the winter, 
_ but at the time the leaves had reached half the normal size, in the 
_ spring of 1915, the tree was completely girdled. On July 1 this tree 
presented an appearance closely similar to that of a small chestnut 
tree girdled by Endothia parasitica. All the leaves above the point 
of inoculation were dead and remained attached to the branches. 
Below the girdled portion, water sprouts had developed, as has been 
frequently described for chestnut trees affected with 2. parasitica. 
Cultures made from this tree showed the fungus to be typical of 
EL. parasitica. Whether this case of parasitism was due to unusual 
virulence on the part of the fungus or to unusual susceptibility on 
the part of the host is, of course, merely a matter of conjecture; the 
latter alternative seems, however, somewhat more probable, as other 
inoculations with this strain of the fungus on Q. prinus and Q. alba 
- failed to show similar results. 

In addition to the above, a somewhat panties observation has been 
made by the writers near ee Mass. In connection with other 
work, a sprout of Quercus niciite about an inch in diameter was 
inoculated with H’'ndothia gyrosa on July 15,1914. When this inocu- 
lation was made the tree was partly (about one-fourth) girdled. 
£. gyrosa developed normally and by October 1, 1914, had produced 
several pycnidial stromata. No change was apparent when the inocu- 
lations were examined in May, 1915. 

LE’. parasitica was abundant in the region, however, and apparently 
gained entrance through the cuts originally made, for when the plat 
was next visited, August 17, 1915, the sprout appeared quite dead, 
though still retaining its full-sized dead leaves. Further examina- 
tion showed numerous pycnidia of /. parasitica in addition to those 
of L’. gyrosa near the region of the original inoculation. The pycnidia 
of /. parasitica were on all sides of the stem, while those of ZL’. gyrosa 
were confined to the portion above the cuts made in inoculating. The 
mycelial fans typical of 2. parasitica were abundant also. These 


70 BULLETIN 380, U. S. DEPARTMENT OF AGRICULTURE. 


observations leave no doubt that the tree was girdled and killed by 
LE’. parasitica. 

Endothia parasitica in exceptional cases undoubtedly attacks othard 
hosts than Castanea, producing cankers and sometimes causing the — 
death of the host. The results of the inoculations just recorded | 
appear to indicate that some unusual conditions of host or parasite — 
must obtain in such cases. Whether such a combination of conditions | 
or factors will ever become sufficiently frequent to lead to serious | 
destruction of Quercus or other forest trees remains to be determined. | 


ENDOTHIA PARASITICA ON CASTANEA SPP. 


Although found occasionally on species of other genera, Xndothia 
parasitica is dangerously pathogenic only on members of the genus 
Castanea. The parasitism of this fungus on the American chestnut 
(Castanea dentata) was first proved by Murrill (57) and has since 
been demonstrated by numerous investigators. "i 

When ELndothia parasitica was discovered in the United States it . 
was considered by some investigators to be a native fungus which | : 
had suddenly become parasitic, and various theories were advanced — 
to account for the supposed unusual susceptibility of the host. As 4 
enumerated by Clinton (18, p. 391), the factors suggested include ¥ 
winter injury, drought injury, fire injury, weakened condition due : 
- to continued coppicing, and reduced amounts of tannic acid due 

perhaps to weather conditions. | 3 

Continued study by many investigators in different localities has, — 
however, fully confirmed the observation originally made by Met- — 
calf and Collins in 1910 (53) that “a debilitated tree is no more © 
subject to attack than a healthy one” and that E'ndothia parasitica 
is actively parasitic on the healthiest specimen of Castanea dentata 
in case there is opportunity for wound infection. The writers have - 
personally made over 1,200 inoculations of /. parasitica on Castanea 
dentata without finding a single individual that showed any re- ~ 


sistance. 
CASTANEA ON LIMESTONE SOILS. 


Not only are all trees susceptible, but so far as is known no con-— 
dition of soil, altitude, or moisture renders them more resistant to 
the disease. The idea has been held by some writers that chestnuts 
grown on limestone soils were immune to the disease, and the plant- 
ing of chestnut orchards on such soils was advocated. This view 
is held by Gulliver (38, p. 53), who sums up his observations in two 
regions in Pennsylvania as follows: 

In every series of tracts taken from limestone to vette shale soils, the 
percentage of blight is least at a comparatively short distance * * * from — 


the edge of the limestone. Tracts on soils derived from limestone whic a 
show the highest percentage of blight seem to be those where the soil has 


cee! 


ENDOTHIA PARASITICA AND RELATED SPECIES. TE 


4 become acid from underground drainage. Chestnut trees on soils. derived 
from other alkaline rocks show less blight than is found in the trees on shale 
soils with limestone underneath. 

On the other hand, Detwiler (24, p. 67) reports observations in 

the Lizard Creek valley which seem to show that these relations do 
not always occur. He says— | 

A belt of limestone borders Lizard Creek valley on the south, and the per 
cent of infection is as high in that region as elsewhere. Infection centers 
have been found near limestone quarries, where the roots of the chestnut pene- 
trated to bedrock. 

Actual proof or disproof of the truth of this idea was peculiarly 
difficult, since chestnut is but rarely found growing naturally on 
calcareous soils. During the summer of 1914, however, a careful 
study of the chestnut on certain portions of limestone areas in west- 

_ ern Maryland and western Connecticut was made. These localities 
- were chosen because they were convenient in connection with other 
work, the blight had been present for several years in both States, 
and thorough State geological surveys made the location of the lime- 
stone areas very easy. The two States also are sufficiently far apart 
to eliminate sources of error that might arise from local weather 
conditions. | 
___In western Connecticut chestnut was abundant on glacial till over 
the Stockbridge limestone of this region. Chestnut was also grow- 
ing directly over limestone at various points near Danbury, Twin - 
Lakes, Chapinville, and Lakeville. Several localities near the latter 
place were kindly pointed out by Dr. George E. Nichols. Near Dan- 
bury every tree examined showed the blight in a more or less ad- 
vanced stage, while near the other towns, all in the northwest corner 
of the State, nearly 50 per cent of the trees were blighted. About 
- 80 inoculations were made on sprouts in this region, and all 
_ except two developed cankers quite as rapidly as did check inocula- 
tions made on the trap ridge west of Hartford. 
_ Chestnut is very rare on the Shenandoah limestone in the Hagers- 
town and [Frederick valleys of western Maryland. A number of 
_ chestnut trees were, however, located growing on limestone soil near 
_ Frederick Junction and Adamstown in the Frederick valley. The 
_ disease was already established west of Adamstown, where 20 per 
cent of the chestnuts were either diseased or dead. Twenty-two in- 
 oculations were made on niné chestnut sprouts in these two regions, 
and all developed typical cankers quite as rapidly as the checks made 
in similar sprouts growing over Baltimore gneiss 50 miles east. 


RECESSION OF THE CHESTNUT IN THE SOUTHERN STATES. 


_ While it has been definitely proved that Hndothia parasitica is 
_ pathogenic on healthy chestnut trees, one of the points brought for- 


72 BULLETIN 380, U. S. DEPARTMENT, OF AGRICULTURE. 


ward by the advocates of the “ weakened host” theory seems to be ~ 
fully established; that is, that the chestnut trees have suffered se- — 


verely in the southern Appalachian regions previous to the present | 


epidemic, in some cases being practically exterminated, so that the 
range is now considerably less than formerly. The evidence on this 
point has been summarized by Clinton (18, pp. 408-418). Various 
writers quoted by him cite fire injury and borers and other insects 
as causes for this recession. 
Long (48, p. 8) considers a root rot due to Armillaria mellea as — 
“very probably an important factor in the gradual recession of the 
chestnut” in North Carolina. It seems probable that all of the 
above-mentioned factors, and perhaps others, have played a part in 
the destruction of the hese a in this region. 


RELATIVE SUSCEPTIBILITY OF SPECIES OF CASTANEA. 


The importance of Castanea dentata as a timber and nut tree and 
its abundance in eastern North America, where the blight is preva- 
lent, has made the chestnut bight an object of much investigation. | 
Descriptions of the nature and importance of the disease, the rate 
of its spread, methods of distribution, and attempted methods of 
control have been given in detail by Anderson (1-5), Clinton (12-15), 
Heald (89-41), Metcalf (51 and 52), Metcalf and Collins (53), Ran- 
kin (62), and others. It may be sufficient here to state that the 
fungus enters the host through a wound in the bark, probably never 
or very rarely through lenticels or natural cracks, grows chiefly in 
the cambium, penetrating for only short distances into the wood, 
and kills the tree or branch by girdling. Once a tree is attacked, 
it is only a question of time till it succumbs. 

The chinquapin (Castanea pumila) was found by Murrill (58) in 
1908 to be attacked by E'ndothia parasitica. Rogers and Gravatt — 
(65) in 1915 made inoculations of 2. parasitica on C. pumila and 
found that the parasite grew as rapidly on this host as on (C.. dentata. 
They attribute the apparent resistance of the chinquapin to its com- 
parative freedom from bark injury, a view also held by other writers. 
Pantanelli (60) and Metcalf (52) have proved that the European 
chestnut is readily susceptible to the disease. 4 

The only chestnuts thus far observed which show any resistance 
to Endothia parasitica are those of oriental origin. Metcalf (51) 
first pointed out the resistance of the Japanese chestnut. This 
observation has since been confirmed by Clinton (18, p. 375), who 
“failed to produce the disease in a Japanese variety in the [Conn.] 
station yard, although the bark was inoculated in 16 different places.” 

Van Fleet (84), in describing the spread of the chestnut blight in 
his breeding plats at Washington, D. C., says (p. 21): “ The Asiatic 
chestnuts and the chinquapin-Asiatic hybrids are plainly highly 
resistant.” 


-ENDOTHIA PARASITICA AND RELATED SPECIES. fis’ 


Morris (56) sums up eight years’ observation of the effect of the 
chestnut blight on 26 species and varieties of chestnuts at Stamford, 
Conn., as follows: 

Every one of the 5,000 American chestnut trees became blighted * * * 
None of [the grafted varieties or seedlings of European and Asiatic varieties 
appear] to be as vulnerable as the American chestnut, but most of mine are 
now dead. Korean chestnuts and chestnuts from the Aomori regions in 
Japan resisted the blight until six years of age. Since that time they 
have shown a marked tendency to blight, but resist it better than does 
the American chestnut * * * None of the American species of chinquapin 
+ * * has blighted with the exception of two limbs * * * None of the 
specimens of Castanea alnifolia for] * * * of Castanea mollissima has 
blighted, but these latter include only five trees. 

These observations as to the resistance of the oriental varieties of 
chestnut when grown in America are of particular interest in con- 
nection with the observations of Meyer in the region where he dis- 
covered Endothia parasitica native. In his letter to Fairchild, writ- 
ten from Santunying, China, June 4, 1913, Meyer makes the following 
notes with reference to the effect of the blight in that region: 

This blight does not by far do as much damage to Chinese chestnut trees as 
to)the American ones * * * 

Not a single tree could be found which had been killed entirely by this 
disease, although there might have been such, trees which had been removed 
by the ever-active and economic Chinese farmers * * * 

Dead limbs, however, were often seen and many a saw wound showed where 
limbs had been removed * * * 

The wounds on the majority of the trees were in the process of healing 
eng = | * 

Old wounds are to be observed here and there on ancient trees. 

Meyer’s photographs taken near Santunying substantiate his state- 
ments. Certainly no specimens of C. dentata in a blight-infested 
region in this country could survive to the age of the Chinese chest- 
nuts shown in his photographs. 

That the Chinese chestnuts are by no means uniformly resistant, 

however, is clearly shown by Meyer’s later notes. On the label of a 
package of L'ndothia parasitica collected on chestnut at Tachingko, 
Shantung, China, March 21, 1914, he writes, “ Trees very severely 
attacked, many dying off,” and in a letter written from the same 
place he says, “ A serious canker; many of the trees here were killed 
By py it.” , 
Further evidence that the virulence of Endothia parasitica on Chi- 
nese chestnut differs in different parts of China is found in subse- 
quent communications from Meyer. From a point near Chingtsai, 
Chekiang, China, on July 15, 1915, he writes: “ All around Hang- 
chow and west of it one finds the chestnut trees seriously attacked by 
this destructive bark fungus.” 

On July 11, 1915, near Changhua, Chekiang, China, he com- 
ments, “ With the exception of near Taianfu, Shantung, chestnuts 


7 


. % 
74 BULLETIN 380, U. S. DEPARTMENT OF AGRICULTURE. ee 


are much more severely attacked in the Chekiang Province than 
either in Chihli, Shansi, or Shensi. Could the greater humidity of 
central China be of assistance to a more vigorous development of @ 
this destructive fungus?” - 


COMPARISON OF HOST RELATIONS. 


It will be seen from the above description of the host relations of — 
the various species that while some other members of the genus 
(2. gyrosa, e. g.) may have slight parasitic tendencies, Hndothia — 
parasitica alone is an active parasite. The contrast is still more 7 
striking in the section of the genus to which Z. parasitica belongs, ~ 
for ’. fuens and L. fluens mississippiensis, which resemble /. para- — 
sitica so closely in their morphological characters, and to a less 
degree on culture media, and are common on Castanea, are almost. 
purely saprophytic. This fact is established by the work of Ander- — 
son (2), Clinton (18), and others, and by two years’ field observa- 
tions and several thousand inoculations made by the writers and 
their colleagues. a 

The host relations of the Sinai are equally striking. Although 
Endothia parasitica is so pathogenic on Castanea dentata that this 
tree has been practically exter minated over several hundred square ~ 
miles of its natural range and its extinction is threatened, the fungus 
has been only occasionally found as even a weak parasite on the ~ 
closely related genus Quercus, and never, to the writers’ knowledge, ~ 
on Fagus. 

During the course of this work the writers have fipeee continually — 
impressed with the possibilities of a physiological study of . para- 
sitica and one or more closely related species which might throw ~ 
some light on the fundamental question of the nature and cause of — 
parasitism. No other case is known to the writers of a virulently 
parasitic fungus and a closely related purely saprophytic one which ~ 
will grow readily and fruit on a large variety of artificial media, 
which are readily distinguishable on those media, and remain con- 
stant for hundreds of generations. . 


SUMMARY. 


The pathological and economic importance of this group of fungi ~ 
was first recognized when the chestnut-blight fungus was discov- | 
ered in New York in 1904. E 

This organism was first referred to the genus Diaporthe, but 
was later shown to belong to the genus Endothia, : 

The specific identity, relationships, and native home of this para- 
site were at first uncertain. Some pathologists considered it a native — 
organism which was attracting attention and causing injury chiefly — 


ENDOTHIA PARASITICA AND RELATED SPECIES. 75 


by reason of the weakened condition of the chestnut trees. Others 
believed it to be of foreign origin. Its recent discovery in China 
and Japan has settled this question. 

To determine positively the identity of the organism, a thorough 
study was made of the types or authentic specimens of all the species 
of Endothia obtainable. Asa result of this work a revision of avail- 
able species of the genus is presented. This is based upon the field 
and laboratory study of over 600 collections. Over 4,000 cultures 
have also been studied. 

Endothia gyrosa (Schw.) Fr. is the type of the genus, which is 
naturally divided into two sections, chiefly by the character of the 
ascospores. In section 1 they are short, cylindric to allantoid, and 
continuous or only pseudoseptate. This section contains two species, 
E£’. gyrosa and LF’, singularis. 

Section 2 has oblong-fusiform to oblong-ellipsoid uniseptate as- 
-cospores. This contains four species and one variety, Hndothia 
fluens, F. fluens mississippiensis, EF’. longirostris, EF. tropicalis, and 
FE. parasitica. FE. tropicalis is a hitherto unrecognized species. 

Radiating layers of yellowish or buff mycelium situated in the 
bark and cambium of the host are found to be constant and dis- 
tinctive characteristics of Yndothia parasitica. None of the other 
species studied shows this character. 

All species of the genus possess a stroma having a distinctive 
yellow to reddish color. 

There is no division of stroma into distinct layers, as deseribed by 
some authors. Pycnidia or perithecia may arise in any portion of 
the stroma. Most commonly where pycnidia and perithecia are both 
present the pycnidia are above the perithecia, though the reverse 
arrangement is sometimes observed and all intermediate conditions 
frequently occur. 

The stromata of the species of section 1 are larger, more erumpent, 
and contain more numerous pycnidia than those of section 2. E’n- 
_ dothia singularis is especially striking in this.respect. The stromata 

of section 2 are smaller and very similar in all the species. 

The pycnidia consist of more or less irregular chambers or locules 
- in the stroma. 

_ The pyenospores are small in most species and furnish no very 

distinctive specific characters. The pycnospores of Yndothia trop- 

icalis are, however, constantly larger and more variable in size than 

those of the other species. 

_ Paraphyses have been described by some authors, but have never 
been observed by the writers. 

___ The ascospores in the species of section 1 are very similar in size 
and shape. Those in section 2, though similar, have been found by 

_ thorough study and careful measurement to show constant though 


76 BULLETIN 380, U. S. DEPARTMENT OF AGRICULTURE. 


slight differences, as indicated in the tables of measurements and 
ratios. . 

Numerous cultures of all the species on a variety of media show 
that each species has constant and distinctive characters of growth 
and color. 

All the species grew equally well in light or darkness, and no de- 
cided differences in temperature relations have been demonstrated. 

The species appear to have well-defined geographic limits of 
distribution, which have been approximately determined for the 
American species. The distribution of the species does not coincide 
with that of the hosts, but seems to be determined in part by soil 
and climatic conditions. 

Endothia fluens has the widest distribution, being frequent and 
widely distributed in Europe and the eastern United States, and also 
occurring in Asia. 

Endothia parasitica is evidently of oriental origin. Specimens 
have been received from five rather widely separated localities in 
China and from two localities in Japan. In the eastern United 
States it is now abundant from Maine to North Carolina and is 
rapidly spreading south and west. It has already destroyed most 
of the chestnut trees within a radius of 100 miles of New York City. 

The species have rather definite host relations. 

Endothia gyrosa has been found on five genera of plants, viz, Cas- 
tanea, Fagus, Liquidambar, Quercus, and Vitis. 

Endothia singularis occurs, so far as known, only on Quercus 
species. 

Endothia fluens has been found in America only on Castanea and 


Quercus, but in Europe it occurs on Alnus, Carpinus, Castanea, 


Corylus, Quercus, and Ulmus, and has been reported on Aesculus, 
Fagus, and Juglans. 

Endothia fluens mississippiensis has been found only on Castanea 
and Quercus. 

Endothia tropicalis is known only on Elaeocarpus. 

Endothia parasitica has been found on Acer, Carya, Castanea, 
Quercus, and Rhus, but at present is only ey as a serious para- 
site on Castanea. 

Upon the American species of Castanea it is actively parasitic 
under all the conditions of soil and climate observed. Oriental 
species of chestnut are more or less resistant to the disease both in 
America and their native homes. 

None of the species except HYndothia DOr ORCS has thus far been 
found to be actively parasitic. 


ae. ee 


LITERATURE CITED. 


(1) ANpERsSon, P. J. 

1914. Morphology and life history of the chestnut blight fungus. Com. 
Invest. and Control Chestnut Tree Blight Disease in Penn. Bul. 
7, 44 p., 17 pl. 1918. 

and ANDERSON, H. W. 
1912. The chestnut blight fungus and a related saprophyte. In Phyto- 
pathology, v. 2, no. 5, p. 204-210. 
(3) 1912. Hndothia virginiana. In Phytopathology, v. 2,-no. 6, p. 261-262. 


(4) 19138. The chestnut blight fungus and a related saprophyte. Penn. 
Chestnut Tree Blight Com. Bul. 4, 26 p., 6 fig. 


(5) and Bascock, D. C. 
1913. Field studies on the dissemination and growth of the chestnut 
blight fungus. Penn. Chestnut Tree Blight Com. Bul. 3, 45 p., 
14 pl. 
(6) and RANKIN, W. H. 


1914. Endothia canker of chestnut. N. Y. Cornell Agr. Exp. Sta. Bul. 
347, p. 531-618, fig. 77-101, pl. 36-40 (1 col.). Bibliography, p. 
611-618. 
(7) Batts, W. L. 
1908. Temperature and growth. Jv Ann. Bot., v. 22, no. 88, p. 557-591, 
11 fig. 
(8} BerKetry, M. J. 
1836. British Fungi . . . 886 p. London. (Smith, J. HE. English 
Mlora, v. 5, pt. 2.) 


and Brooms, C. E. 
1875. Enumeration of the fungi of Ceylon. Jn Jour. Linn. Soc. [London] 
Bot., v. 14, p. 29-140, pl. 2-10. 


(10) 1877. Supplement to the enumeration of fungi of Ceylon. Im Jour. Linn. 
Soc. [London] Bot., v. 15, p. 82-86, pl. 2. 


(11) CrsatiI, ViINcENzo, and Noraris, G. DE. 
1863. Schema di classificazione degli sferiacei Italici aschigeri ... In 
Comm. Soc. Crittog. Ital., v. 1, p. 207, 240. 
(12) CrintTon, G. P. 
Chestnut bark disease [1907]. Jn Conn. Agr. Exp. Sta. 31st/32d Ann. 
Rpt. [1906]/08, p. 345-346. 
(13) 1908. Chestnut bark disease, Diaporthe parasitica Murr. [1908]. In 
Conn. Agr. Exp. Sta. 31st/32d Ann Rpt. [1906]/08, p. 879-890. 
(14) 1911. Chestnut bark disease. In Conn. Agr. Exp. Sta. Bien. Rpt. 1909/10, 
p. 716-717, 725. 


(15) 1912. Some facts and theories. concerning chestnut blight. Jn Penn. 
Chestnut Blight Conf. Rpt. 1912, p. 75-83, 9 pl. 

(16) 1912. Chestnut blight fungus and its allies. In Phytopathology, v. 2, 
no. 6, p. 265-269. 

(17) 1912. The relationships of the chestnut blight fungus. Jn Science, n. s., 
v. 36, no. 989, p. 907-914. 


(9) 


vi 


78 BULLETIN 380, U. S. DEPARTMENT OF AGRICULTURE. 4 


(18) 1918. Chestnut bark disease, Endothia gyrosa var. parasitica (Murr.) _ 
Clint. Jn Conn. Agr. Exp. Sta. Ann. Rpt. 1911/12, p. 359-453, _ 
pl. 21-28. : 

(19) Cook, M. T., and TAUBENHAUS, J. J. , 

1911. Relation of parasitic fungi to the contents of the cells of the host — 
plants. I. The toxicity of tannin. Del. Agr. Exp. Sta. Bul. 91, 
W7 p., 48 fig. 

(20) CooKE, M. C. ‘ ; 

1878. The fungi of Texas. Jn Ann. N. Y. Acad. Sci, v. 1, no. 5/6, p. 
177-187. 

(21) CurRrREY, FREDERICK. 

1858. Synopsis of the fructification of the compound Sphaeriae of the 
Hookerian herbarium. Jn Trans. Linn. Soc. London, vy. 22, pt. 3, 
p. 257-287, pl. 45-49. 

(22) 1865. Supplementary observations on the Sphaeriae of the Hookerian 
herbarium. Jn Trans. Linn. Soc. London, v. 25, pt. 2, p. 239-262. 

(23) Curtis, M. A. 

1867. .. . A catalogue of the Indigenous and Naturalized Plants of the 
State. 158 p. Raleigh, N. C. (Geological and Natural History 
Survey of North Carolina, pt. 3, Botany.) 


(24) DETWILER, S. B. 
1914. Observations on sanitation cutting in controlling the chestnut blight 
in Pennsylvania. Final Rpt. Penn. Chestnut Tree Blight Com. — 
1913, p. 638-73, 1 pl., 3 maps. 
(25) ARLE, | F. S. 
1901. Some fungi from Porto Rico. In Muhlenbergia, v. 1, no. 2, p. 10-23. 
(26) Extzis, J. B., and EverHart, B. M. | 
1892. The North American Pyrenomycetes. ... 793 p., 41 pl. Newfield, 
Nid. i 
(27) FAtgcuirp,. 1: °G: 
1913. The discovery of the chestnut bark disease in China. Jn Science 
n. s., v. 38, no. 974, p. 297-299. 
(28) Fartow, W. G. 
1912. The fungus of the chestnut-tree blight. Jn Science, n. s., vy. 35, no. 
906, p. T1 7-722. 
(29) Faut1, J. H., and Granam, G. H. 
1914. Bark disease of the chestnut in British Columbia. Forestry Quart., 
v. 12, no. 2, p. 201-208. 


(30) Fries, EK. M. 


1882. Systema Mycologicum. ...v. 2. Lundae. 
(31) 1828. Elenchus Fungorum. ... v. 2. Gryphiswaldiae. 
(32) 1830. Eclogae fungorum. . . . In Linnaea, Bd. 5, Heft. 4, p. 497-553. 
(33) 1849. Summa Vegetabilium Scandinaviae. ... sect. 2. Upsaliae. 


(84) FucKEL, LEOPOLD. 
_ 1861. Enumeratio Fungorum Nassoviae. 126 p., 1 col. pl. Wiesbaden. 
(35) 1869-70. Symbolae Mycologicae. Beitrige zur Kenntniss der Rheinis- 
chen Pilze. 459 p., 6 col. pl. Wiesbaden. (Jahrb. Nassau. Ver. 
Naturk., Jahrg. 23/24.) 


ENDOTHIA PARASITICA AND RELATED SPECIES. 79 


(36) FUISTING, WILHELM. 
1867. Zur Entwickelungsgeschichte der Ge daksaycbbcits In. Bot. Ztg., 
Jahrg. 25, No. 23, p. 177-181; No. 24, p. 185-189; No. 25, p. 
193-198; No. 39, p. 305-811. 


(37) Futon, H. R. 
1912. Recent notes on the chestnut bark disease. Jn Penn. Chestnut 
Blight Conf. Rpt. 1912, p. 48-56. 


(38) GULLIVER, F. P. 
1914. [Report of] geographic work. Jn Final Rpt. Penn. Chestnut Tree 
Blight Com. 1913, p. 52-53. 


(39) Heaxp, F. DE F. 
1913. The symptoms of chestnut tree blight and a brief description of 
the blight fungus. Penn. Chestnut Tree Blight Com. Bul. 5, 
15 p., 16 pl. 


(40) 


GARDNER, M. W., and STUDHALTER, R. A. 
1915. Air and wind dissemination of ascospores of the chestnut blight 
fungus. Jn Phytopathology, v. 3, no. 6, p. 493-526. 


(41) and STUDHALTER, R. A. 
1918. Preliminary note on birds as carriers of the chestnut blight fungus. 


In Science, n. s., v. 38, no. 973, p. 278-280. 


(42) HitcHcock, Epwarp. 
1829. A Catalogue of Plants Growing without Cultivation in the Vicinity 
of Amherst College. 64 p. Amherst, Mass. 


(43) HoOwHNEL, FRANZ VON 
1909. Fragmente zur Mykologie. IX. Mitteilung, Nr. 407 bis 467. In 
Sitzber. K. Akad. Wiss. [Vienna], Math. Naturw. K1., Abt. 1, 
gr Bd. 118, Heft 9, p. 1461-1552, 1 illus. 


(44) 1913. Fragmente zur Mykologie. XV. Mitteilung, Nr. 798 bis 812. In 
Sitzber. K. Akad. Wiss. [Vienna], Math. Naturw. Kl, Abt. 1, 
Bd. 122, Heft 2, p. 255-309, 7 fig. 


(45) Kererer, W. E. 
1914. Pathological histology of the Endothia canker of chestnut. In 
Phytopathology, v. 4, no. 3, p. 191-200, 3 fig. 


(46) Koppen, W. P. 
1901. Versuch einer Klassification der Klimate vorzugsweise nach ihren 
Beziehungen zur Pflanzenwelt., 45 p., 2 illus., tab., 2 fold. maps. 

Leipzig. 


(47) Livineston, B. E., and LivinesTon, GRAcE J. 
1913. Temperature coefficients in plant geography and climatology. In 
Bot. Gaz., v. 56, no. 5, p. 349-875, 3 fig. 


{48) Lone, W. H. 
1914. The death of chestnuts and oaks due to Armillaria mellea. U. S. 
Dept. Agr. Bul. 89, 9 p., 2 pl. 


{49) Merrxet, H. W. 
1906. A deadly fungus on the American chestnut. Jn 10th Ann. Rpt. 
N. Y. Zool. Soc. 1905, p. 97-108, illus. 


80 BULLETIN 380, U. S. DEPARTMENT OF AGRICULTURE. 


(50) Merriam, C. H. 
1895. Laws of temperature control of the geographic distribution of terres- 
trial animals and plants. In Nat. Geog. Mag., v. 6, p. 229-238, 
pl. 12-14 (col. maps). 


(51) MeEtTcaLr, HAVEN. 
1908. The immunity of the Japanese chestnut to the bark disease. Jn. 
U. S. Dept. Agr., Bur. Plant Indus. Bul. 121, p. 55-56. 


(52) 1912. Diseases of the chestnut and other trees. Jn Trans. Mass. Hort. 
Soc. 1912, pt. 1, p. 69-95. 


and CoLtins, J. F. 
1910. The chestnut bark disease. Jn Science, n. s., v. 31, no. 802, p. 748. 


(54) Monraens, J. F. C. 

1834. Notice sur les plantes cryptogames récemment découvertes en 
France, contenant aussi Vindication précise des localités de 
quelques espéces les plus rares de la flore francaise. Jn Ann. Sci. 
Nat. Bot., s. 2, t. 1, p. 295-307, 337-349, pl. 11-138 (2° ol). 


(55) 1855. Cryptogamia Guyanensis ... Jn Ann. Sci. Nat. Bot. s. 4, t. 3, p. 
91-144, pl. 5. 


(56) Morris, R. T. 
1914. Chestnut blight resistance. Jn Jour. Heredity, v. 5, no. 1, p. 26-29, 
fig. 14-15. 


(57) MurRRILL, W. A. 
1906. A new chestnut disease. Jn Torreya, v. 6, no. 9, p. 186-189, fig. 2. 


(58) 1908. The chestnut canker. Jn Torreya, v. 8, no. 5, p. 111-112. 


(53) 


(59) NowELi, WILLIAM. 
1915. Diseases of lime trees in forest districts. Imp. Dept. Agr. West 
Indies, Pamphlet Series 79, 41 p., 2 fig., 5 pl. 


(60) PANTANELLI, ENRICO. 
1912. Su la supporta origine europea del cancro americano del castagno. 
In Atti R. Accad. Lincei, Rend. Cl. Sci. Fis., Mat. e Nat., s. 5, 
v. 21, sem. 2, fase. 12, p. 869-875. 


(61) Petri, Lvict. 
1913. Sopro una nuova specie di Endothia, EH. pseudoradicalis. In Atti 
R. Accad. Lincei, Rend. Cl. Sci. Fis., Mat. e Nat., s. 5, v. 22, 
sem. 1, fasc. 9, p. 653-658, 2 fig. 


(62) RANKIN, W. H. 
1914. Field studies on the Endothia canker of chestnut in New York 
State. In Phytopathology, v. 4, no. 4, p. 233-260, 2 fig. pl. "ae 


(63) RrHM, HEINRICH. 
1907. Ascomycetes exs. fase. 39. Jn Ann. Mycol, v. 5, no. 3, p. 207-218. 


(64) RipG@waAy, RoBERT. 
1912. Color Standards and Color Nomenclature. 43 p., 53 pl. Washing- 
ton. 


(65) Rocers, J. T., and Gravatt, G. F. 


1915. Notes on the chestnut bark disease. in Phytopathology, v. 5, no. 1 
p. 45-47. 


ENDOTHIA PARASITICA AND RELATED SPECIES. 81 


(66) RupotpeHt, FR. 
1829. Plantarum vel novarum vel minus cognitarum descriptiones. Decas 
secunda. Jn Linnaea, Bd. 4, Heft 3, p. 887-395. 


(67) RUHLAND, WILLY. 
1900. Untersuchungen zu einer Morphologie der stromabildenden Sphae- 
riales auf entwickelungsgeschichtlicher Grundlage. In Hed- 
wigia, Bd. 39, Heft 1, p. 1-79, pl. 1-3. 


(68) Saccarpo, P. A. 
1878. Mycologiae venetae specimen. In Atti Soc. Veneto-Trentina Sci. 
Nat. Padova, v. 2, fase. 1, p. 53-96, pl. 45 (col.); fase. 2, p. 
97-264, pl. 6-17 (col.). 


(69) 1882-1905. Sylloge Fungorum, v. 1, 8, 17. Patavii, 1882,.1889, 1905. 
(70) 1883. Genera Pyrenomycetum Schematica Delineata. 8 p.,14 pl. Patavii. 


(71) 1906. Notae mycologicae. Series VII. Jn Ann. Mycol. v. 4, no. 3.7 pe 
273-278. 


(72) ScHWEINITz, L. D. von. 
[1822]. Synopsis Fungorum Carolinae Superioris ...105 p., 2 col. pl. 
ft. D: 
(73) 1825. Description of a number of new American species of Sphaeriae. In 
Jour. Acad. Nat. Sci. [Phila.], v. 5, pt. 1, p. 3-16, 2 pl. 


(74) 1832. Synopsis fungorum in America boreali media degentium ... In 
Trans. Amer. Phil. Soc., n. s., v. 4, p. 141-316, pl. 19. 


(75) SHEAR, C. L. 
1912. The chestnut-blight fungus. In Phytopathology, v. 2, no. 5, p. 211- 
za. 


and STEVENS, NEIL EH. 
1913. The chestnut-blight parasite (Hndothia parasitica) from China. 
In Science, n. s., v. 38, no. 974, p. 295-297. 


(77) 1918. Cultural characters of the chestnut-blight fungus and its near rela- 
tives. In U.S. Dept. Agr., Bur. Plant Indus. Cir. 131, p. 3-18. 


(76) 


(78) 1916. The discovery of the chestnut-blight parasite (Hndothia parasitica) 
and other chestnut fungi in Japan. Jn Science, n. s., v. 48, no. 
1101, p. 173-176. 


(79) SowrErRBy, JAMES. 
1814. Colored Figures of English Fungi or Mushrooms. Sup. London. 
Pl. 488 is pt. of pl. 420. 


(80) SPRENGEL, KURT. 
1827. Systema Vegetabilium. v. 4, pars 1. Gottingae. 


(81) Sypow, Hans, and Sypow, PAvut. 
1912. Novae fungorum species—VII. Jn Ann. Mycol., v. 10, no. 1, p. 
77-85. 


(82) ‘TRAVERSO, G. B. 
1906. Pyrenomycetae ... In Societa Botanica Italiana, Flora Italica 
Cryptogama. pars 1, Fungi, v. 2, fasc. 1, p. 180-182. 


(83) TuLasng, L. R., and TULASNE, CHARLES. 
1863. Selecta Fungorum Carpologia ... t.2. Parisiis. 


43737°—Bull. 3880—17——6 


82 BULLETIN 380, U. S. DEPARTMENT OF AGRICULTURE. 


(84) VAN FLEET, WALTER. 
1914, Chestnut breeding experience. Jn Jour. Heredity, v. 5, no. 1, p. 19- 
25, fig. 9-13. 


(85) WINTER, GEORG. 
1887. Die Pilze... 928 p. Leipzig. (Rabenhorst, Ludwig. Krypto- 
gamen-Flora... Aufl. 2, Bd. 1, Abt. 2.) 


(86) Zon, RAPHAEL 
1914. Meteorological observations in connection with botanical geography, 
agriculture, and forestry. In Mo. Weather Rey., v. 42, no. 4, p. 
217-223, 1 fig. 


ADDITIONAL COPIES 
OF THIS PUBLICATION MAY BE PROCURED FROM 
THE SUPERINTENDENT OF DOCUMENTS 
GOVERNMENT PRINTING OFFICE 
WASHINGTON, D. C. 
AT 


35 CENTS PER COPY 
V 


wf be 


e 


UNITED STATES DEPARTMENT OF AGRICULTURE 


BULLETIN No. 453 % 


Contribution from the Bureau of Plant Industry 
WM. A. TAYLOR, Chief 


Washington, D. C. PROFESSIONAL PAPER January 20, - 


THE CONTROL OF DAMPING-OFF OF CONIFEROUS 
4 SEEDLINGS. 


By Cart Hartiey, Forest Pathologist, and Roy G. Pirrce, Forest Assistant, Office of 
= 4 Investigations in Forest Pathology. 


CONTENTS. 

5 Page Page 
SSE ee ea a 1 | Cost of disinfectant treatments..........-... 19 > 
Economic importance of damping-ofl........ 1 | Secondary advantages from disinfectant treat- 
Relation between nursery methods and the NOIIE GH Seer 8 ees ce SO ke ee 21 

Pemmniror OLGampime-Ofi ---.....2....-...:... 3 | Conclusions as to soil disinfectants........... 24 
Tests of soil disinfection for the control of Soil treatments reeommended..............- 28 
’ MEMES -OUEp os See LS 5h Sables se iss ses GON SUDIN inthe cits Reman os hei soe oracc, . eee 31 
_ #soil-disinfection tests summarized ..........- 14 


THE DISEASE. 


: Damping-off is a term commonly used to describe the disease caus- 
ing the death of very young seedlings due to various: parasitic fungi. 
' The damping-off of conifers in the United States has been found to 
be caused by the fungi Pythium debaryanum Hesse, Fusarium mo- 
_ niliforme Sheldon, and the common American Rhizoctonia, usually 
‘= referred to as Behm vagum B. and C. var. solam Burt: Other 
species of Fusarium and other fungi are probably also concerned to 
_aless extent. Most affected seedlings promptly fall over and decay. 
_ Those which are not attacked till they are 4 to 8 weeks old may have 
such wiry stems that they merely turn brown and remain standing 
iter death. This later type of injury is caused by parasites in the 
a way as the decay of the more succulent younger seedlings, 
t though nurserymen do not always recognize it as the same thing. 


ECONOMIC IMPORTANCE OF DAMPING-OFF. 


~ Damping-off has been a handicap to nearly all nurserymen who 
‘raise conifers from seed. In most nurseries a large number of seed- 
lings are lost every year. The loss is ordinarily considerably heavier 
than the nurseryman realizes. Very young seedlings decay and dis- 
appear so soon after infection that the number of dead seedlings 
60142°—Bull, 453—17——1 


Me, 


2 BULLETIN 458, U. S. DEPARTMENT OF AGRICULTURE. 


visible at any one time is but a small part of the total loss. Fur- i 
thermore, many of the seedlings are killed immediately after the 


seed sprouts and before the seedlings appear above the soil surface. 
Many failures hitherto attributed to poor germination are in reality 
due to the work of the damping-off parasites in the sprouting seed, 
underground. The high price of most evergreen seed makes this loss 
of young seedlings a serious matter. 

The cost of seed’ ranges from a minimum price of 50 cents per 
pound for western yellow pine (Pinus ponderosa Laws.) collected by 
the United States Forest Service to $2 to $4 per pound quoted by 
commercial seedsmen for the native spruces and $5 to $10 per pound 
for Norway pine (Pinus reswnosa Ait.). The regular annual loss is, 
however, not the most serious result of the disease. The most trouble- 
some thing from the commercial standpoint is the great variation im 
the prevalence of the disease. In some seasons the loss is relatively 
_ slight, while in others the seed beds may be almost a total loss, The 
results of a damping-off epidemic are shown by the poor stand in 
the untreated plats in Plate I. Such epidemics make it impossible 
for a nurseryman to secure any regularity in production. The diffi- 
culty of controlling damping-off has caused many nurserymen to 
give up raising their own seedling conifers. | 

The loss from damping-off can not be figured merely on a basis of 
the number of the seedings destroyed. The most serious aspect of 
the disease is the extent to which planting is discouraged by it. Re- 
forestation of watersheds is one of the great needs of the present time. 
When interest on the cost of a forest plantation is compounded for 
the 80 er 100 years which must elapse between forest planting and — 
timber cutting, a very slight initial increase in the cost of planting © 
stock becomes a heavy charge against the ultimate timber value of 
the plantation, on which the owner must depend for direct returns. 
It is necessary in order to encourage forest planting to eliminate all 
possible cost items in the establishment of plantations. Both the 
average loss and the irregularity in production due to damping-off 
are reflected in the prices of coniferous planting stock, so that the 
disease must be controlled to give the maximum opportunity for 
profitable reforestation. It has previously been possible to import 
pine stock from Europe cheaply. This has resulted in the introduc- 
tion of very dangerous insect and fungous pests. The importation of 
all pines is now prohibited, and the danger of the further introduction 
of parasites on imported stock of other conifers makes it necessary 
that the domestic nursery industry be developed on an economic 
scale that will eliminate all need or incentive for importation. To — 
do this, all important native diseases, of which damping-off is the © 
most serious, must be controlled. 


1 Information furnished by the Office of Forest Investigations, United States Forest Service. 


‘quantity. 


} 


DAMPING-OFF OF CONIFEROUS SEEDLINGS. 3 


RELATION BETWEEN NURSERY METHODS AND THE CONTROL OF 
DAMPING-OFF. 


A great deal has been written, largely in horticultural journals, on 
the methods best calculated to prevent damping-off. It has been 
generally agreed that beds should be well drained and aerated and 
should have no more water or shade than absolutely necessary. Sur- ~ 
facing beds with gravel, coarse sand, or heated sand has also been 
recommended. Alli of these measures have value, but all have their 
limitations. All of them combined are not sufficient to prevent 
heavy losses when the damping-off parasites are present in sufficient 


THE BEST SOIL FOR SEED BEDS. 


In general, where there is a chance to choose between different seed- 
bed sites it is safest from the standpoint of damping-off control to 
select a site with a sandy soil. Either because such soils are better - 
drained or because they contain less organic food matter for fungi, 
damping-off is commonly less troublesome on light than on heavy 
soils. A sandy soil is by no means a guaranty of freedom from 
disease, the heaviest damping-off losses in the writers’ experience 
having occurred on a soil consisting of nearly pure sand. Alkaline 
soils are believed to favor damping-off. If this is found to be the case, 
it may explain the fact that some of the heaviest losses from damping- 
off occur in Nebraska and Kansas rather than in the more humid 
Eastern States. 

Where it is necessary to put seed beds on a soil where damping-off 
is troublesome, the soil may be improved in various ways. Where 
sand is easily available, it may pay to haul it in and mix it with the 
surface soil. Excellent results have been obtained in one case in the 
writers’ experience by making the entire upper 3 inches of the bed 
of very sandy subsoil just dug up. A less expensive procedure which 
has also given indication of value is to cover the seed with subsoil 
taken from a point so far below the surface that it is likely to be free 
from parasitic fungi and an unfavorable medium for their growth. 
It is usually better to cover seed with sand than with heavy soil, and 
- surfacing the beds with coarse sand or gravel after the seed is sown 
and covered is considered helpful, Surfacing the beds after germi- 
_ nation with heated sand applied as hot as the hand can stand has also 
been recommended. ‘Tests by the writers of hot sand on seed beds 
_ Inasandy western soil had no perceptible effect on the disease. 


AVOIDANCE OF EXCESSIVE MOISTURE. 


_ To secure drainage, seed beds are commonly raised from 2 to 3 ° 
_ inches above the paths, and at some nurseries the surface of the bed 
_ is arched to increase run-off. This is probably good practice at most 

nurseries, but on very sandy soils in a dry climate it does not appear to 


4. BULLETIN 4538, U. S. DEPARTMENT OF AGRICULTURE. 


have any value whatever. To secure aeration the best eastern ~ 
nurseries leave their beds entirely open to the wind, or, if side walls — 
are needed to exclude seed-eating animals, they use wire netting 
only. Yet, at a nursery in western Kansas, after trying the rather 
expensive netting sides, it was found by forest officers that as good 
or better results were obtained by using beds with tight board sides. 
It is well known that excessive moisture and shade must be avoided 
in the seed beds. However, in sandy soils or in a dry country there 
is nearly as much danger of getting the beds too dry as of keeping 
them too wet. Drought often kills large numbers of seedlings in 
beds left without water. ; 

Aside from common drought injury the effort to keep seed beds dry 
may result in an entirely different type of trouble. Ifseed beds are 
insufficiently shaded and the soil surface is not kept moist, there is 
at some nurseries serious loss from ‘‘white-spot’’ injury. This injury 
in seedlings up to 3 weeks of age appears as a whitening and shrink- 
ing of the stem just above the ground line. The shrunken area in 
most cases girdles the stem, the seedling falls over, and death follows. 
When the injury occurs on one side only it is usually the south or 
southwest side of the stem that is affected. The symptoms are very 
much like damping-off, the decided white color of the part of the 
stem first affected being the most noticeable difference. This white- 
spot injury is caused not by parasites but apparently by heat, with 
which possibly may also be combined the direct effects of intense 
light. The temperature at the surface of a dry, loose soil exposed to 
the sun may exceed 140° F., a very high temperature for most tender 
plant tissues to endure for any length of time. White-spot injury is 
almost always mistaken for damping-off, and has been observed to 
kill more than half of the seedlings in unshaded beds of even so heat- 
resistant a species as western yellow pine (Pinus ponderosa). In 
withholding water and shade from coniferous seed beds, nurserymen _ 
must be very careful or the loss from drought and white-spot will* 
much exceed the advantage from decreased damping-off loss. Keep- + 
ing the beds dry is impossible in wet weather and dangerous in dry 
weather, and it therefore will never be more than a partial control 
method for damping-off. 


FERTILIZERS. 


The relation between soil fertilization and damping-off has been 
but little investigated. In preliminary tests dried blood and nitrate 
of soda have apparently favored the damping-off parasites, and their 
use on pine seed beds is considered inadvisable. However, in Ver- 
mont‘! tankage has given excellent results against damping-off. It 
is evident that further tests of nitrogenous fertilizers are needed. © ~ 


1 Gifford, C. M. The damping-off of coniferous seedlings. Vt. Agr. Exp. Sta. Bul. 157, p. 170. 1911. 


DAMPING-OFF OF CONIFEROUS SEEDLINGS. 5 


Lime in small quantities has had no appreciable effect, while applica- 
tions at the rate of 1 ton per acre to beds of jack pine (Pinus banksi- 
ana Lamb.) in Nebraska have had bad effects. At Burlington, Vt.,! 
wood ashes have been added to seed beds with disastrous results. 
Lime also caused trouble at Burlington. At Providence, R. L., ° 
a mixture of coal and wood ashes tested by Prof. H. H. York 
seemed to give bad results. Heavy applications of imperfectly rotted 
horse manure have been known to greatly increase damping-off at 
the Nebraska nursery, but at the same nursery well-composted 
manure seems'harmless. It is probably safest to manure beds at’ 
least a year before seed is to be sown on them. No trouble has been 
observed to result from the use of green manures, but it may be- 
found that some such crops harbor damping-off parasites and should 
be avoided. The perennial ragweed of the Southwest (Ambrosia 
psilostachya DC.) serves as a hold-over host for parasitic strains of 
Corticium, so that this and any other weeds known to carry seedling 
parasites should be eliminated from nursery areas. 


DENSITY OF SOWING. 


As with truck crops, it is found that pines suffer most from damping- 
off when sown too closely. A bed containing a stand of seedlings 
which is too dense will not only lose more seedlings than a less 
crowded bed, but it will lose a higher percentage of its seedlings. 
This is due to the ease with which the parasites spread from one 
seedling to another in dense stands. It has also been found with 
jack pine that in tests at two nurseries the damping-off loss in seed- 
lings sown broadcast was only four-fifths as great as in adjacent 
plats sown in drills. In general, beds sown broadcast seem to suffer 
less from damping-off than beds sown in drills, though with western 
yellow pine broadcasting has given no better results than the drill 
method at the nurseries where comparative tests were made. 


TIME OF SOWING. 


Another item in nursery practice in which variation may affect 
damping-off is the time at which seed is sown. At some nurseries 
it makes little difference when seed is sown. In one season beds 
sown in early spring suffer least from the disease. The next season 
the latest sown beds may come out the best. However, at some 
nurseries it is found that there is a best time and a worst time for 
seed sowing. In a New Mexico nursery it has been demonstrated 
that July, the local rainy season, is the worst sowing time from the 
damping-off standpoint. At two western nurseries (in Nebraska and 
Colorado) the Forest Service has found that yellow-pine seed beds 

sown in late autumn are comparatively free from damping-off. 
Repeated tests during two or three successive seasons are necessary 


1 Gifford, C. M. Op. cit. 


4 


6 BULLETIN 453, U. S. DEPARTMENT OF AGRICULTURE. 


to determine for any particular nursery whether or not damping-off 
losses are regularly less in beds sown at a particular time. It. is 
thought that fall sowing is least likely to succeed in localities in 
which the soil does not remain constantly frozen during the winter. 


TESTS OF SOIL DISINFECTION FOR THE CONTROL OF DAMPING-OFF. 


The entire matter of the factors controlling the work of the 
damping-off parasites and the methods of seed-bed management 
most likely to decrease the disease needs a great deal of further 
examination. At present adherence to the best known nursery 
practice will not avoid considerable annual losses at most nurseries 
or prevent epidemic years in which the beds of certain species are 
entire failures. The multiplicity of parasites and the different con- 
ditions of soil and climate to be met so complicate the problem that 
it has been found most profitable to make a direct attack on the 
parasites by the use of disinfectants rather than wait for results by 
the indirect means of changed nursery management. 

Experiments in seed-bed disinfection have been carried on by the 
writers or in pursuance of their recommendations for the past seven 
years and at a number of nurseries. At different times assistance 
has been rendered by Mr. R. D. Rands, Dr. J. V. Hofmann, Dr. T. C. 
Merrill, Mr. S. C. Bruner, and Mr. G. G. Hahn. 

Definite and satisfactory control of the disease has been secured 
by soil disinfection at every nursery in which extensive experiments 
have been conducted, and preliminary tests at additional nurseries 
indicate that while different places require somewhat different pro- 
cedure, damping-off everywhere can be controlled by proper disin- 
fection of the seed beds. The economic results at all of these nurs- 
eries are briefly described in the following pages, together with a 
summary of the published results of other investigators. 

RESULTS OF SOIL DISINFECTION AT NURSERIES WHERE REPEATED TESTS HAVE BEEN 
MADE. 

The first tests were made in pine seed beds in the very sandy soil of 
the United States Forest Service nursery at Halsey, Nebr. The ex- 
perience at this nursery was in many ways typical and will therefore 
be described in some detail. 

The first attempt was to control the disease by applying disin- 
fectants after the seedlings appeared above ground. This failed, 
partly because the disinfectants injured the seedlings and partly be- 
cause the parasites were found to do a great deal of their work before 
the seedlings came up. A number of disinfectants were then tested in 
applications at or before seed sowing. Of these, commercial sulphuric 
acid appeared the cheapest and most effective. Both heat and formal- 
dehyde, the means usually recommended for disinfecting greenhouse 
and truck soils, proved less reliable as well as more expensive. 


DAMPING-OFF OF CONIFEROUS SEEDLINGS. Pi 


The treatment finally adopted consists of three-sixteenths fluid 
ounce of sulphuric acid per square foot of seed bed, applied in solu- 
tion immediately after the seed is sown and covered. The amount of 
water used to dissolve the acid varies from 1 pint per square foot 
when the soil is wet to 2 pints when the soil is dry. In all disinfec- 
tion of seed beds by chemicals the quantity of the disinfectant used 
per unit area of soil surface seems to be the important variable. The 
disinfectant must be dissolved in sufficient water to permit its dis- 
tribution through the soil to a depth of several inches, but within 
certain limits the concentration of the solution as applied does not 
appear to be an important factor. The adherence of some investi- 
gators to the concentration of the solution used as a measure of soil 
treatment makes their work difficult to correlate. 

In the earlier tests of acid at Halsey chemical injury to the pines 
occurred in beds treated with acid at the time of sowing. It was 
found that dormant pine seeds were not injured by acid, but that the 
root tips of the seedlings in acid beds were often killed just after 
germination commenced. The way in which this injury occurred 
- made it evident that it was due to the concentration of the acid in 
_ the surface soil. Evaporation of water from the soil surface seemed 
_ to bring up the disinfectant from the lower soil, just as alkali salts 
come to the surface in alkali soils. Watering the beds frequently 
during the germinating period prevents such surface concentration 
and in practice has been found entirely to prevent injury to the seed- 
* lings. The method of protecting the seedlings from acid injury at 
this nursery is to water the seed beds frequently from the time seed 
is sown until a few days after germination, when the root tips have 
penetrated one-half inch into the soil. After this time they are prac- 
_ tically safe from further injury. The beds are watered daily in ordi- 
‘ary spring weather, every other day in misty or rainy weather, and 
twice daily when the maximum temperature exceeds 80° F. In 
clear weather each watering is at the rate of approximately 14 pints 
_ per square foot of bed. In cold, cloudy weather 1 pint per square 
foot is-found sufficient. (Two-tenths inch of rainfall is equivalent 
to 1 pint per square foot.) 

_ ‘The acid treatment was repeatedly tested on different species of 
_ pine during different years and at different times of the year. In all 
_ cases it resulted in increased stands. The results of all the acid tests 
in which the above watering system or its equivalent was followed 
are given in Table I. 

In addition to the three species given in this table, a test on a 
series of plats of Corsican pine (Pinus laricio Poir.) gave excellent 
results; an accident prevented the securing of exact figures. Some 
of the tests included in the table were conducted on a considerable 
‘seale, the total area involved being 8,350 square feet in the treated 


8 BULLETIN 4538, U. S. DEPARTMENT OF AGRICULTURE. 


” 


plats and 547 feet in the untreated plats. In the case of the larger 
plats, counts of seedlings. were made only on sample areas scattered 
through the plats. The percentages of germination and of death 
are based on counts of all seedlings on 246 square feet in the treated — 
plats and 145 square feet in the untreated plats. The surviving 
seedlings were counted on these sample areas and also on additional 
areas, totaling 406 square feet for the acid plats and 196 square feet 
for the untreated plats. Damping-off is so variable that only 
repeated and extensive tests of this sort are-entirely reliable. 


TaBLE I.—Control of damping-off of pines by three-sixteenths fluid ounce of sulphuric acid 
per square foot of seed bed applied at sowing time, Halsey, Nebr. 
Absolute results. Relative results. 
Number 
Species. of sepa- Eee Death Final 
rate tests. * |Germina-| per hun-| stand |Germina- Death Final 
tion.! /dred seed-| based on | __ tion. S stand. 
lings.2 |jseedsown. 
Per cent. Per cent. 
Pinus banksiana 3... 114) Aeid 5... 32.0 15.2 26.4 161 35 267 
None.... 20.3 43.7 9.9 i 100 100 
P. ponderosas. 62. - 3 | Acid... 66.3 12.0 58.7 132 33 178 
None 59.3 36.7 33.0 100 190 100 
IPs FeESMOSA eres oe. ce 3 | Acid. 70.0 38.7 40.7 112 53 254 
None. 62.7 73.7 16.0 100 100 100 
Average 8.00.00: 17| Acid....| 56.3 22.0 41.9 135 43 233 
None 44.4 51.4 16.3 100 100 100 


1The germination percentage takes into account only seedlings which appear above the soil. Seeds 
which started to germinate but did not reach the point of breaking through the soil are not included. 

2 The death percentage includes all seedlings which died from damping-olf and also any which may have 
died from drought or chemical injury after the seedlings came up. Seedlings broken by hail or other 
mechanical means or killed by insects are not included. 

3 Germination and death figures obtained from only 9 of the 11 jack-pine tests. 


The acid in practically all cases caused a marked increase in the 
number of seedlings that came up, as well as a decrease in the death 
rate after coming up. Damping-off was not entirely controlled. 
There was still a loss of 22 per cent after germination in the treated 
plats, but the loss in the untreated plats was nearly two and one-half 
times as great. The combined effect of increased germination and 
decreased death rate was a large increase in the number of healthy 
seedlings produced. (See Table I, columns headed “Final stand.”) . 

It is especially to be noted that in jack pine and Norway pine, 
the species with which the most extensive tests were made, more 
than 250 healthy seedlings were obtained in the treated plats for 
every 100 obtained from equal quantities of seed in the untreated 
plats. The results of the acid treatment of Norway pine are strik- 
ingly shown by the difference in stand in the treated and untreated 
plats shown in Plate I, figure 1. , 

Since the foregoing tests were conducted, the acid treatment has 
been put into regular use on all spring-sown beds at this nursery and 
the success of the treatment further confirmed by the continued 
good results secured. 


ee 


Bul. 453, U. S. Dept. of Agriculture. PLATE I. 


Fic. 1.—NORWAY-PiNE SEED BED, 1 YEAR OLD, HALSEY, NEBR. 


Plat in center untreated Remainder of bed treated at time of sowing with a solution containing 
three-sixteenths fluid ounce of sulphuric acid per square foot of bed. Practically allofthe seedlings 
in the untreated plat have been destroyed by damping-off. Photographed by Charles B. Pool 
(F 1). 


Fic. 2.—WESTERN YELLOW-PINE SEED BED, KANSAS SANDHILLS. 


Foreground untreated. Background treated at time of sowing with a sulphuric-acid solution. Most 


. of the seedlings in the untreated plat have been destroyed by damping-off. Phot hed by Dr. 
’ J. V. Hofmann (F 2). “ Per py danipins- otographed by Dr 


Bul. 453, U. S. Dept. of Agriculture. PLATE II. 


Foreground untreated. Background treated with sulphuric-acid solution before germination. 
cake. te 3) in inches. Note the difference in height of the seedlings after the first season’s 
growt - 


x 


ke ahead WS. 


Fia. 2.—JACK-PINE SEED BED, KANSAS SANDHILLS. 


Plat at left treated with one-fourth ounce and plat at center with three-eighths ounce of sulphuric 
acid per square foot. Plat at right untreated. Note the relative freedom from weeds in the 
treated plats. The apparently thin stand of trees in the treated plats is due to the very small size 
of the young seedlings of this species of pine. Actual counts in these plats showed the stand to 
ne as rey (ns can be grown without subsequent overcrowding. Photographed by Stephen C. 

runer 4). 


DAMPING-OFF OF CONIFEROUS SEEDLINGS. 9 


At nearly all of the other nurseries sulphuric acid was also found 
successful in controlling damping-off. However, because of dif- 
ferences in soil and climate, the treatments required elsewhere dif- 
fered in some details from that at Halsey. On a still lighter sand 
_ in Kansas sand hills, which was probably also somewhat more alka- 
line, it was found that damping-off could be controlled best by a 
- heavier treatment of acid—one-fourth fluid ounce per square foot in 
ordinary spring-sown beds, and five-sixteenths or three-eighths ounce 
in beds sown in the fall or very early spring. The watering required 
during the germinating period to prevent injury to the pines was 
less than at Halsey. The losses in untreated beds at this nursery were 
exceptionally heavy. In the treated beds it was not possible to 
reduce the damping-off loss to as low a figure as at Halsey, probably 
because of the common occurrence of Fusarvum monliforme, a fungus 
exceptionally able to quickly reinfect treated beds. The success of 
the treatment from the economic standpoint, however, was greater 
than at Halsey. Without the treatment, failure occurred in the 
_ seed beds more often than success, and stock could not be raised at 
a reasonable expense. With the treatment, success was the rule, 
and the economical production of stock became possible. The dif- 
ference in stand between treated and untreated plats at this nursery 
is shown in Plate I, figure 2. _ 

At a single nursery on a fine sandy soil near Morrisville, Pa., it was 
found that it was more difficult than at Halsey to prevent acid injury 
to germinating seedlings. This was a nursery at which tests were 
made during asingle season only. Itis mentioned at this point merely 
to show the difference in behavior of acid in different soils. Even one- 
twelfth fluid ounce per square foot caused injury to the pines at Mor- 
risville. indications from the small series of tests conducted there 
were that one-eighth ounce of acid per square foot would probably 
prove effective against damping-off and harmless to coniferous seed- 
lings if followed by sufficiently frequent watering during the germi- 
nating period. It is likely that this soil was slightly acid to start 
with. 

In marked contrast to the experience at Morrisville are the results 
obtained at Fort Bayard, N. Mex., Monument, Colo., and Haugan, 
Mont. At all of these places acid atthe rate of three-sixteenths ounce 
or more per square foot has been applied to the beds at sowing in - 
repeated tests, without any injury to the seedlings that could be 
detected by the forest officers in charge at the nurseries. At Fort 
Bayard Mr. H. C. Turner has tested the acid very thoroughly for four 
successive seasons and in quantities up to five-eighths ounce per square 
foot without finding any injury to seedlings. Even three-sixteenths 
ounce proved reasonably efficient in decreasing damping-off, and the 
_ five-eighths ounce treatment reduced the loss to less than 1 per cent. 
60142°—Bull. 453—17——2 


Le, tok 


-_— 


10 BULLETIN 453, U. S. DEPARTMENT OF AGRICULTURE. _ i ® 


At Haugan the acid has been used for three years and damping-off — 
has been practically abolished in the beds treated. These three — 
nurseries differ from the preceding three in that the soil is heavier 
and there is no need of any extra watering in order to prevent chem- 
ical injury to the seedlings. st 

At a seventh nursery an entirely different condition was encoun- 
tered. The seed beds were located on a rather heavy soil near 
Garden City, Kans. This soil effervesced vigorously when treated 
with acid, yielding 0.23 per cent of carbon dioxid from the surface 
soil and over 1 per cent from the subsoil in a test made by the Bureau 
of Soils. Acid treatments had no effect on damping-off in this soil, 
owing presumably to the high carbonate content and consequent 
alkalinity which the effervescence indicated. Tests with copper 
sulphate, one-fourth ounce per square foot, and zinc chlorid, one-half 
ounce per square foot, showed that both these and heavier treatments 
were effective against damping-off. The results are given in Table II. 
TasLe I1.—Control of damping-off of pines by one-fourth to three-fourths ounce copper 


sulphate and one-half to one ounce zinc chlorid per square foot of seed bed, Garden City, 
Kans. 


Absolute results. Relative results. 


a FS 
er O : 
Species and time of sowing. Disinfectant. cla oes corte pins Com tee ne 
mina-| dred | based | mina- | Death. 
tests. | tion, | seed- lonseed| tion. stand. 
lings. | sown. 
Pinus austriaca: Per ct. Per ct 
ee espe ay" 9 { ree oa ce oot Pe sab 
ODO 2 se kc ee soe 5. 91.0 3} 210 
PIINR 5 soe aaa eee see zi 
Zine chlorid......- 1 |f 37-5 99.0 ms 192 99 | (a) 
Ltr oe oes } { 19.5 | 106.0 0 100 100 | (a) 
P. banksiana: 
Copper sulphate... 3 |f 27-1 35.2 | 16:4 105 56 212 
WOR 5. see an cece \ 25.9 62.3 7.6 100 100 100 
1c: pa Be, eee oy ate LE a 
Zine chlorid......-. . 9 |f 30.7 | 27: 6a -2150 130 40 362 
None..2: 50.30 \ : { 33.7 69.0] 5.8] 100} 100 100 
y s 
Copper sulphate. .. 16.6 67.8 9.0 143 101 143 
Nee ee \ 2 {is 67.0| 63} 100] 100] 100 
SPLINE >. 5155. 230b sae ee 
is Zine chlorid.....-. 2 37.5 20.0 | 28.9 264 30 452 
WONG, 2 seg 2 oe ap - \ 14.2 66.0 6.4 100 100 100 
Copper sulphate |.___... 28. 0 37.7 | 188 148 57 289 
Average, fall and spring. .|{ and zinecchlorid. x 
Nofiei}2.. ee-htcks 18.9 66.1 6.5 100 100 100 
P. ponderosa: . 
Copper sulphate... 9 |f 46.1 20.1 | 34.8 113 34 217 
Nones. fs. asst i \ 40.9 59.8 | 16.0 100 | 100 100 
12 Ee a MPC i OC) pe a 
Zine chlorid...-.-. 9 |f 42.9 16.1 | 33.1 117 28 183 
C0 a Sage ge \ { 36.6] 57.4} 181 100 | 100 100 
Copper sulphate... 58. 1 24.0 | 42.2 114 53 147 
‘ Gee 7 ee \ ss { 50.9| 45.1 | 287| 100] 100] 100 
Sprig 2 So soe eee he eae 
iaere Zine chlorid.....-- 6 61.3 | b11.8 | .46.6 116 30 150 
BONG ..2 >. pees \ { 52.7 | 639.1] 31.0 100 100 100 
Zine chlorid and he ee 52.1| 180] 39.2| 115 36 167 
Average, falland spring..|{ copper sulphate. : : 
Bi atria in ar Pages pape ge) eee 45.3| 50.4] 23.5! 100} 100} 100 


a No expression possible. 6 The damping-off percentage was determined in but five of the six tests. 


s 


DAMPING-OFF OF CONIFEROUS SEEDLINGS. 11 


Copper sulphate could probably have been used with success in 
_ quantities less than one-fourth ounce per square foot. A three-eighths 
ounce zinc-chlorid treatment proved unsuccessful. Both disinfect- 
ants were dissolved in water and applied in most cases just after seed 
sowing, as was done with acid. Both were found harmless to the 
dormant seed in these concentrations, but both were capable of 
injuring germinating seedlings in just the same way as is described 
for acid at Halsey. This injury was prevented by extra watering 
during the germinating period, in the same way as acid injury was 
prevented at the Halsey and Kansas sand-hill nurseries. The 
amount of this extra watering needed at the Garden City nursery was 
very slight. 

An interesting thing that developed at this nursery, as well as at 
the Kansas sand-hill nursery, was the control of spring damping-off 
by treatments applied during November of the preceding year. Part 
of the fall-sown plats whose results were shown in Table IL were 
treated at the time of sowing and part as soon as the soil thawed the 
following spring. Though the seedlings did not appear until the 
following April, disinfectants applied in November seemed to protect 
them from damping-off as well, or practically as well, as disinfectants 
applied in March. At this nursery and at the five preceding at which 
repeated tests were made, the treatments developed have been put 
into regular large-scale use by the nurserymen, with good results. 
RESULTS OF SOIL DISINFECTION AT NURSERIES WHERE TESTS HAVE BEEN LIMITED 

TO A SINGLE SEASON. 

At Porvenir, N. Mex., Dundee, Ill., Lincoln, Nebr., the nursery of 
_ the State Board of Forestry in Vilas County, Wis.,and the greenhouses 
of the United States Department of Agriculture at Washington, D.C., 
single-season tests of sulphuric acid have given good results. At all 
of these places no need was found for any special watering provision for 
the prevention of chemical injury from the acid. The tests at 
Dundee and Lincoln were made during an unusually rainy season. 
It may develop that in years with less rain more watering will be 
needed at these places. 

At four other nurseries where disinfectants were tested in this pre- 
_ liminary way the results were less definite. At Morrisville, Pa., 
already referred to, there was distinct evidence that a very weak Wee 
treatment with sufficient watering during the germinating period will 
be entirely successful in controlling the small amount of damping-off 
which normally occurs there. One-eighth ounce of acid per square foot 
it is thought will be sufficient. Insufficient watering prevented the 
securing of exact information from the tests conducted. At Poca- 
tello, Jcahia, a single test of acid on beds of Douglas fir had no con- 
spicuous effect on the amount of damping-off. As the soil is found 
to effervesce on the addition of acid, success with acid does not 


12 BULLETIN 453, U. S. DEPARTMENT OF AGRICULTURE. 


appear probable. At Cass Lake, Minn:, acid was tested on seed beds 
of Norway pine (Pinus resinosa) during a period of weather so abnor- 
mally cold and wet that the seed lay in the ground for a number of 
weeks before germination was completed. ‘Under these conditions, 
for the first time in the writers’ experience, the acid treatment of the 
beds at the time of sowing resulted in decreased germination. No 
special watering was needed to prevent injury to the tips after the 
seedlings began to come up; in fact, very frequent watering given one 
bed resulted in less germination and therefore poorer results than in 
acid beds with no extra watering. Despite the decrease in germina- 
tion, the acid beds, because of the almost complete control of damping- 
off by the treatment, finished the season with an average of 135 seed- 


lings for every 100 in the untreated plats, and the acid plats which. 


were not given excessive water had 151 seedlings for every 100 
in the untreated plats. This fact and the fact that acid beds which 
had first been treated with lime and were thereby kept from injury to 
the seed produced 228 seedlings for every 100 in the untreated plats 


indicate that in ordinary seasons the treatment with acid alone will - 


be entirely successful. The use of lime with acid is usually undesirable 
because by neutralizing the acid it permits the parasites to resume 
work soon after treatment. Formaldehyde gave better results than 
acid at Cass Lake. While it is thought that this would not be the 
case in a normal season, it is evident that further tests are needed to 
determine what treatment to use. 

The danger in drawing conclusions from the results of three or 
four test plats is shown especially well by the results obtained by 
Prof. H. H. York, of Brown University, in testing treatments recom- 
mended by the writers. Treatments involving five-sixteenths ounce 
of sulphuric acid, five-eighth ounce of zine chlorid, and 24 ounces 
of cane sugar, respectively, per square foot of bed, resulted in final 
stands from 44 to 15 times as dense as in most of the untreated plats. 
One untreated plat, however, gave a stand as dense as that on the 
treated plats. This throws doubt on the reliability of the results on 
the other plats and indicates that only repeated tests, each with 
plenty of untreated plats for abundant comparison, are reliable 
enough to be used as a basis for conclusions. 


At several of the nurseries mentioned above other soil treatments 


were tried with success. At Glenview, IIll., where acid failed, copper- 
sulphate treatment resulted in doubling the final stand. The good 
results obtained on otherwise untreated soil at Dundee, Ill., by the 
addition of cane sugar were rather surprising; indications of damp- 
ing-off control by sugar were also observed at Garden City, Kans., 
East Tawas, Mich., and Providence, R.I. Further tests are required. 
At East Tawas, a test of acid in an unfavorable season did not give 


as good results as desired, while formaldehyde resulted in a doubled | 


stand. 


: 


ee ee eee eee 


eee 


DAMPING-OFF OF CONIFEROUS SEEDLINGS. 13 
RESULTS OF SOIL DISINFECTION IN GREENHOUSE TESTS. 


In the greenhouses of the Department of Agriculture at Washing- 
ton, D. C., disinfection of soil by steam pressure has proved reason- 
ably effective in controlling damping-off of pine seedlings in most of a 
rather large number of tests conducted during the winter months. 
During the summer there is so much reinfection that the results of 
heat disinfection are uncertain. A single test of sulphuric acid in 
the spring of 1915 indicated the value of acid treatment in reducing 
damping-off in the greenhouse. Four flats of jack pine were treated 
with sulphuric acid in quantities of three-sixteenths to three-eighths 
ounce per square foot just after sowing. The relative survival in the 
acid flats, taking the average survival in the untreated flats as 100, 
was 128. The relative survival in flats disinfected by steam was only 
105. Three-sixteenths ounce of acid per square foot gave as good 
results as heavier treatments. The soil used in this experiment was 
a mixture of seven parts loam, four parts sand, two parts manure, 
and one part leaf mold. 


RESULTS IN DISINFECTING THE SOIL OBTAINED BY OTHER INVESTIGATORS. 


Spaulding,’ who appears to have been the originator of the use of 
sulphuric acid for soil disinfection, has tested acid and other disin- 
fectants at several places. In greenhouse tests formaldehyde and 
copper sulphate were found valuable, but the sulphate injured seed- 
lings. At Saranac Inn, N. Y., formaldehyde apparently increased 
damping-off one season and controlled it in a later season, while 
sulphuric acid injured seedlings and gave results which from the 
economic standpoint were inconclusive. 

At Burlington, Vt., results with disinfectants in pme-seed beds have 
been reported by Spaulding,? Jones,’ Gifford,t and Burns.» Formal- 
dehyde applied five days before sowing and allowed to evaporate for 
two days before sowing killed part of the seed. All of the writers 
found formaldehyde of decided value in controllmg damping-off. 
Jones and Spaulding report a single test in which but one-tenth 
ounce (0.106 ounce) of formaldehyde was used per square foot and 
excellent results obtained. The subsequent tests reported have been 
with amounts of 0.48 ounce or over per square foot. The treatment 
used by Burns, of 0.58 ounce of formaldehyde per square foot, applied 


1 Spaulding, Perley. The damping-off of coniferous seedlings. In Phytopathology, v. 4, no. 2, p. 73-88, 
2fig., pl. 6. 1914. 

—— The treatment of damping-off in coniferous seedlings. U.S. Dept. Agr., Bur. Plant Indus. Cire. 
4,8p. 1908. 7 

2 Spaulding, Perley, 1914. Op. cit. 

» Jones, L.R. The damping-off of coniferous seedlings. In Vt. Agr. Exp. Sta. 20th Ann. Rpt., 1906-7, 

p. 342-347. 1908. 

4  aleg C.M. The damping-off of coniferous seedlings. Vt. Agr. Exp. Sta. Bul. 157, p. 141-171, 10 fig., 
4pl. 1911. . 

> Burns, G. P. Studies in tolerance of New England forest trees. I. Development of white pine seedlings 
in nursery beds. Vt. Agr. Exp. Sta. Bul. 178, p. 125-144, 2 fig.,4 pl. 1914. 


14 BULLETIN 453, U. S. DEPARTMENT OF AGRICULTURE. 


11 days before sowing, with the beds tightly covered during the — 
interim, appears to have been entirely harmless and very effective 
against the disease. Burns found the sulphuric-acid treatment used 
by the writers at Halsey, three-sixteenths ounce per square foot 
applied at time of sowing, as effective as the formaldehyde and non- 
injurious. Spaulding,’ reportmg tests made in 1907 and 1908, also” 
obtained excellent results with acid, which was not tested by Jones 
and Gifford. He in addition obtained good results in preliminary 
tests with copper sulphate and with sulphur. 

Acid was also used at an unnamed locality by Giissow,? with 
excellent results. 

Charcoal, an amendment rather than a disinfectant, is reported by 
Retan? to be of value against damping-off in the clay soil at Mont 
Alto, Pa., and to result in the increased size of pine seedlings. A layer 
3 inches deep was spaded into the soul. Annual treatment. with this 
amount would, of course, be impracticable. However, Retan states 
that the effect of such charcoal addition is permanent. Further 
experience seems necessary to confirm the permanent value of char- 
coal for preventing damping-off on this and other soils. A single test 
by the writers of a lighter application of charcoal at the Cass mare 
nursery proved unsuccessful. 


SOIL-DISINFECTION TESTS SUMMARIZED. 


The writers’ experience with soil disinfectants at the different 
nurseries, as well as the experience of other experimenters, has been 
so varied that it is rather difficult to correlate the results. Correlation 
will be made easier by reference to Table III, in which are summed 
up all of the successful tests of treatments of coniferous seed beds of 
which the writers have been able to learn. In the tests at Halsey, the 
Kansas sand hills, Garden City, Lincoln, Cass Lake, Dundee, Glen- 
view, and Kast Tawas, the experimental treatments were applied by 
the writers or their assistants, with the cooperation of those in 
charge of the nurseries. At Fort Bayard the tests were conducted by 
Mr. H. C. Turner, at Monument by Mr. W. H. Schrader, at Porvenir 
by Mr. H. D. Burrall, at Pocatello by Mr. Arthur P. Say, im Vilas 
County, Wis., by Mr. W. D. Barnard, at Providence by Prof. H. H. 
York, at Morrisville under the direction of Mr. John Foley, and at 
Haugan by forest officers, following recommendations made by the 
writers. 


1 Spaulding, Perley, 1914. Op. cit. 

2 Giissow, H. T. Diseases of forest trees. Jn Com. Conserv. Canada, Rpt. ist Ann. Meeting, 1910, p. 
136-137. 1910. 

3 Retan, G. A. Charcoal as a means of solving some nursery problems. In Forestry Quart., v. 13, no. 4 
p. 25-30. 1915. 


15 


DAMPING-OFF OF CONIFEROUS SEEDLINGS. 


<CSYIVUIeY ,, IapuN veg + 


“you ATqeqorg ¢ 


*Aimfur [vormeyd yuoaoid OF, z 


*po}Vo1{UN UL ONT Youe 10; s}eyd poyees} ur JequINN 7 


‘ayeyd 
-[ns zeaddoo I0j enjea 948d 
-IpurSsjse} AreurultTerd {4804 
Q[SUIS UT JUET[IOXe OseyUe 


*qoojied AyTvorj0vid poyiod 
-0.1 [0.1}U00 OSBESIp ‘S}UNOD ON 


eN[VA JoVxe ‘s}[Nsel poos 


JIA. pejsey eyeydins soddog 


“plio[yo oUuiz pus’ 


‘eyeydtns 1eddoo soy entea 


O}VOIPUL S$}Se} AIVUTWITTOIg 


*peurul 
-19j0p JOU eN{VA JO ooIs 
-8p ‘PIIO[YO OULZ IOJ oNTVA 
e}eoIpuL sysey ArvULUToIg 


or 


‘sy IeUIEYy 


oe ete (e) | : , 
Societe Skokie Meee Se eet fra fd ee OL $10}V31]SOA UI 
4 Hy mee hoa mee £04 a I0q30 ea syNsey 
Gee eoy cee wane ea OR eta i. tees oe ee at ae NL, | See () | *sre0d ¢ 
ri Roe chan Soe a ene et Pe pare til he eit SO LLI g 
=25 Jes g 
ene ae a Me Sg Se epsyepreariot{ see ae s 01 § ee te 
eee mise dyandndy) f° ee ope at eee he ere ye ve 
“Voy 
Slavica: co tlalh ate hee | pue opAyopremio7 |-----sox |} 32045 9I¢ al 
gee 
pue ‘oyeqdns Jo 
ge nee rere lee ais ous ee) -doo ‘epAyepreulioy |--"" "sex | €&% Jat 
s20uNnO 
6 8 L 9 g F 
*ys0q se 
mane poe zeorpul Sey 
: p ul 400} rpueys | yuepue 
PA ON ons Bao a. -1ayem | arenbs |Surjnsay| -eputjo 
e14XA red IequnNn 
qunoury 


—Dpo}PoIpUl YOY Syueuryve14 yWeyIOd UIT 


Sh | ab cere 3s esByuey) | 
= ~" pros ormyding 7)"""~-"-"  seroeds ¢ ‘sould 
103° |--epAygoepreurs0,7 
SLA ‘UOJsUILINgG 
“pas PR eh ee ata <t OD s ~----9urd MOTToA TL109S0 AA 
:WIBOT : “yuo; ‘uesne_y 
‘gonids uueul 
-jesuq ‘Ig sevi[snog 
t ""prov ofinydyng | ‘eurd mMoTjeaA ureise A 
:MVOT ‘O[0D ‘yueTINUO_, 
8 0} “++ **praoTyo oUTZ\}... 2. 
i on bs Ep aia STG -----9utd Moros 119480 A\ 
smreoT AABOY 
b “xXOoW ‘“N ‘paedeq 4107 
TUT “77 *"pHopyo oUTZ|).........- 
Foi |-eyeydyns paeaea sopoods ¢ ‘Sour 
:7U9}09 9} BU0q, 
-180 YSTYy WIT ‘ureo] Apues 
euy ‘suey ‘AIO Uepley 
Oe Aste se Opseees Segoe ee seroeds fF ‘sourg 
:puvs OUY ‘ST[IU PUBS SBSUByT 
ot i" pos opmading |s-“""*~ 5" seroeds ¢ ‘seurg 
SadUngQ :pues ouy SIqeNn ‘Aes[t yy 
& rg I 
* JOO} 
eienbs 
Jed ‘poppe sourysqns 
Seta *pesn satoeds 
un I 
oes ae pure ‘ed 44 [Ios ‘A4I;v00'T 
*qU9UIYBOLT, 4 


*sqWeur} eel} [NJssooong 


‘ACV NGG FAV SISAL CALVaAdTY AUAHAA SHOVIG LV 


‘suafvuos fo fJfo-burduwp fo ,01,U00 ayy sof s7Uawydad) quos fo ssa. —]I]T AIAVI, 


Se 
’ 
f 


—_ soo er are, 5 et ih i 


BULLETIN 453, U. S. DEPARTMENT OF AGRICULTURE. 


16 


Sere AS ca feral ee eae ee ee “(e) | Le T af ~* prow opmmydyng jo“ 7 soos ooe “ould 
:pues 
eug ‘stm ‘AjUNOD SseirA 
: t $074" | prow ormydyns 
COME). sat ie 
Or ‘d 4 SIT) ge Nad one ox 86% T 4q poeMmol[[Ow ire: Pra ape 
S05. uoUL ely PIOG. JOP Fy eres inqdjng dad [ns seddoo § § ** OUIT] PoYB[s-ITV ~-*-eurd ABMION 
eINSy MO] JO Uoryeuv[dxe 10,7 ‘prio yo ouiz “yeyq] |... Co) N £01% OFZ T $04 ¢ -- epAYop[eulso 7 
; See Po (e) | “098% | cer 7 *OYF |° plow’ opmnydng 
:pues Suu ‘exe sseg 
| ‘ourd MOTTOA 
uleyseoM pues ‘sonids 
Seo BaS . os ae eae ee Aa pelle ee plioyyo ourz |°"-"~-*(e) | = OST Z S20, 4% |--provormydmng | enjq ‘eonids ABMION 
SURO 
Apues AJoA SiqeN ‘upoouly 
“praoyyo 
"seyeUogivo sulejuo0N Pog |"-------prowormydng |-°--- 27° CUPS SO ae SCs See ee A ee ane oe ee cee an ee na ee ig ey Cai at? ea “IY sv[snog 
. UIBOT ‘OYVpyT ‘ojjezV00g 
‘ayeydins 1eddoo 
pues opAyopleuliog |---------*" Pl4o[yo ourzy |--"" >" (c) | $03 891 " $0942 |--provormydyng | ~~ ----vonids uuempesuy 
"S20UNO "S2IUNO SURO] 
Apues !xew ‘N ‘iTWeAIOg 
Or 6 8 L 9 g F | $ G I 
*j00J 
*ys0q SB erenbs 
z pepeeu |pezvorpul aoa Jod ‘peppe soueysqng 
pee, ; sul 4ooj rpueys | yuepue pesn 
Bel eg as! oe Saad | -10jeM | orenbs | 3ury[nsey] -epurjo | yanoury 5 
"syIeVUE Y BIYXT red Jequiny __pasn saroeds 
qunoury pue ‘ed 44 [Los ‘A41]vo0'yF 


—po}BOIpUl OIA SyUIUT} VET} JU IOdUIT 


*U9UI}BAI J, 


*S}USUT4BET4 [NJsseoong 


"NOSVGQ FIONIG V OL GXLINI'T NATG FAV SLSAT, AUTH AA SHOVIG LY 


‘ponutju0j—suafiwoo fo ffo-buidwuop fo 7017U09 ay} sof syuawmjna.) pros fO 878A], —]]][ ATAV 


Li 


¢CSYIVUISY ,, JopUN 909 5 “you ATQeqold ¢ *Aimfut peorureyo WwueAeId OF, z *pozeeT]UN Ul OOT Foe 107 syed poyver) Ul JoquUINNy 1 
eB | “soTU} 
7, *pesveioep Atjuervdde yo | soyour 
4 SIGUE PaUEIO MOMS] |LISO Me scmecaa Le RES kor fates ce eee [oes eee | Serre keine cbt tomar. Tir mere eNgnee SATO LG Hem tak: GLCOOLEU DE |p wate ao Aepo Seg ‘oipy yuoyy 
4 *JUeT[eOXe SB Psqr1os \ 
2 -Op JOeye ‘Mossny JO Sqnsey | "7-7 epee Ree a ee eee ee SSR ee men gy Soi ee Ti mee Feet og ee proe pee ee ek eee epeury 
CMe llin te eae Se a Oa, ee ea ee ree BOX | eae ae a eee a ee ee {prose a1mMYy[Ng ||... prow Gy our 
RA od { we ee ee See Settee wm elees ee mee reese eet e sete meslassecs ON SS AOS odie a!) O10 eS wale ain al|/o & oS em mimia © 0.6 S'S a's la) e 6'a\} = {opAYopl[eulso 7 Apuvs . A N uur ovUBIES 
Oe nT eee fo a ee a ere eS COR ts aero ape Sele SSS nee ae Se a One. ORI Le 
oD) “Surprnedg jo sinsouy Gi tds ae coal Fad a aa ke Oo nae Ee A Nets Cael ED SON where We ane a TA co me yah aes ome -eyeydrns soda} "oy ‘stno’yT 4g “esnoyueery 
EUS DEI CER lie 0 are Sees ulito a eet tet gic. ey 2S aes all Zale oR AR ET Ia ONGC asic (eee. ale See eT Onlemeres saa opAYOP [CULO iT 
EY SIE etal oie a! ee oe ae" = Sa ere eer 8 TE feo |" "* 7 “(c) | 07% | 8zr I 0s as POP See” Mees eurd your 
SG suvo[ Apues Oo °C 
ical ‘TOUSUIYS A ‘osnoyueely 
~ *pouruliejep 
7, SoUidiee soleorplT OMG A Ws to reas Pee Geahc ea soe a hee sox | ? G) Teas oS cies <a oe >> prov ormydyng jsonids AeMION pue sould 
SURO] 
3 Apues ouy ‘eg ‘Ol[IAsoW 
SPOUTMUCTOP HOU UIEOTR Opn Wie Pete cole enh Ok GI =n) aii ets sa CE so Sate ON | £2 (+) T Br Hib Wer eer resns eur 
ica SPIAO HeROLUrZ DIKE = plow JOR ta Ent" The eee eesls sensi os epAYopleulsoy4|----- sox | 3 (+) ii ae * spice Qrinyd yng, a6 > ee eurd ABMION 
(Ss) WIVUPowSa* = DOTEOTDUIe ORGAN cart atc nae sie ee Bae Sk a ees sox | $092 G) Ti 8 --*"*pTOTYO OULZ : 
SURO 
2 Apues “]T ‘y ‘eouepraoig 
° ‘ould 
Rian eee) ot. nie se me ae Sel eee Ge prow opmmgdyng |---------- $04; | 002 z £07 | gepAyopreursog | ory pue curd AvMION 
7, :puvs oUyY “Yor ‘SVMBT, SVT 
= *plio[yo oulz 
py DUBIN OR. OLIN ae ss = Fe ee eee cline “(e) | $092 10z z y -ayeydyns aeddog |*~*** yooyuey ‘ay sepsnoq 
= :ureo] Apues ‘TTT ‘MoTATELD 
— } *(porreut 
QA 4OU [IOS UO) 
: “poq ig ne eo a es See ON : 042 I8L T r 04 : Sa i ous 
JO j00} elenbs rod 1018M Jo ; : J 5 
quid syjinoy-o0ry} ATuo uy }| P®l1@ UI Wo) resus Kouore Dest I —Aq | )..----+-++-gurd uerysny 
euvo ‘(9uoTe pesn Uses) plworyo ourz ON LLT Z SUIMOS 109JB 
ose err ee ela wey) epAyopreUurso,T , asnl pemorjog 
y : Il iy pI 1a IZ, g T 03 g " “epAyopleulo yy 
; ale ees os CHT 7 g eyeydyns seddop 4 
pee (8) | ¢ OFT 7 POUT ee ep sso 
3([IVUL WTA peqeer} 
\ Apjsoul) ureoy -"[[T ‘eopung 
f 


-~ 


18 BULLETIN 453, U. S. DEPARTMENT OF AGRICULTURE. 


In most of the treatments listed in Table III the substance used 
was applied just after the seed was sown and covered. Formaldehyde 


kills some of the seed if so used and was accordingly applied several 


days before seed sowing. Either the soil was treated a week or more 
before sowing in the formaldehyde plats and kept covered with heavy 


paper for a few days after treatment, or else the treatment wasmade | 


but two or three days before sowing and no paper was used. Even 
with these precautions part of the seed was killed in the tests at 
Burlington, the Kansas sand hills, and Glenview. Zinc chlorid killed 
the dormant jack-pine seed in two heavily treated plats at Garden 
City which were sown and treated in the fall and remained dormant 
throughout the winter. It ordinarily produces no such effect. Sul- 
phuric acid has also shown a tendency to decrease the germination 
percentage in two or three tests of fall treatments, but ordinarily has 
no such effect in spring-sown beds. It has never had more than a 
slight delaying effect on germination except during very wet, cold 
weather, and its harmful effect on dormant seed in spring-sown beds 
is negligible. Copper sulphate shows even less tendency than sul-’ 
phuric acid to injure dormant seed. Sulphuric acid, copper sulphate, 
and zine chlorid are all inclined in some soils to injure the root tips 
of seedlings just after germination begins; on such soils the injury 
to seedlings can be prevented by very frequent watering during the 
germinating period. Column 7 of Table III indicates for the best 
strength of each successful treatment whether or not such extra 
watering is required. It will be noted that in formaldehyde beds 
extra watering is nowhere necessary. For the other three disinfec- 
tants it is more commonly necessary on very light sandy soils than on 
heavy soils. 

Air-slaked lime, powdered sulphur, and charcoal were applied any 
and in the tests aA by the writers were raked into the upper 
3 inches of soil. Copper sulphate was applied in the form of dry 
powder in the tests reported by Spaulding. Sulphuric acid, formal- 
dehyde, zine chlorid, and in the tests reported by the writers copper 
sulphate were applied in solution. The strength of all treatments 
is expressed in the number of ounces of substance per square foot of 
bed. For sulphuric acid and formaldehyde the fluid ounce (29.574 
ce. c.) is the unit of measure, while for all other substances the avoir- 
dupois ounce (28.35 gm.) was used. Three-fourths of an ounce per 
square foot is practically equivalent to 1 ton per acre. The amount 
of water used in dissolving the disinfectants varies from 1 to 24 pints 
per square foot. For a soil already wet 1 pint is sufficient; for a dry 
fine-textured soil 24 pints may be needed to secure a proper distri- 
bution of the disinfectant. Ordinarily, 14 or 1% pints per square 
foot are satisfactory.. 


1 Spaulding, Perley. The treatment of damping-off in coniferous seedlings. U. 8. Rect Agr., Bur. 
Plant Indus. Cire. 4,8 p. 1908. 


DAMPING-OFF OF CONIFEROUS SEEDLINGS. 19 


COST OF DISINFECTANT TREATMENTS. 


Because of the differences between the nurseries where tests have 
been made, both in the details of the treatment used and in the scale 
of the operations and the equipment of the nursery in such matters 
as water supply, it is impossible to make any statement as to the 
exact costs of treatment. 

At two of the nurseries (Fort Bayard, N. Mex., and Haugan, 
Mont.) mentioned in the foregoing pages, at which the treatments 
have been in use long enough to permit a definite statement, all that 
is needed is an application of acid solution to the beds just after 
sowing. The treated beds thereafter require no more attention than 
do those untreated. At six other nurseries, where the acid has 
been in use for a less time, the same appears to be true, while for a 
seventh nursery, where copper sulphate gives the best results, the 
same simple method of application appears satisfactory. For these 
nine nurseries, then, the treatment which has so far appeared most 
effective involves no expense except that of the single disinfectant 
application. Different amounts of disinfectant are required for 
different soils, and because of the rather high cost of transporting 
sulphuric acid the price of that disinfectant varies greatly in different 
localities, so that exact costs of the treatment can not be given. It 
is very evident, however, that both the sulphuric-acid and the 
copper-sulphate treatments applied in this way are decidedly cheaper 
than either the formaldehyde or heat disinfection methods as used 
in out-of-door seed beds of tobacco and other truck crops. At 
many railroad centers sulphuric acid can be obtained in carboy lots 
_ for 24 cents per pound * or even less, while copper sulphate should not 
_ ordinarily exceed 8 cents per pound.t With copper sulphate one- 
_ fourth avoirdupois ounce and sulphuric acid one-fourth fluid ounce 
3 per square foot will be sufficient or more than sufficient at most 
nurseries. Judging from the experience of truck-crop experimenters 
and from the results of the writers and others with formaldehyde at 
_ several nurseries, one-fourth to one-half fluid ounce per square foot 
of the more expensive formaldehyde will be néeded on most soils to 
secure sufficient disinfection. If it develops that it is necessary to 
use the tight cover prescribed by most writers to prevent premature 
evaporation and to treat additional soil for use in covering the seed 
after sowing, these items will further increase the expense of for- 
-maldehyde treatment. The expense of steam disinfection of out-of- 
door seed beds of tobacco is given by Johnson ? as $7.50 to $10 per 
thousand square feet of bed. This is a much higher cost than is to 
be anticipated with acid or copper-sulphate treatment. 


4 1 These prices prevailed prior to the outbreak of the European war. It is assumed that the present 
higher prices are temporary. 

_ 2Johnson, James. The control of diseases and ‘eet of tobacco. Wis. Agr. Exp. Sta. Bul. 237, p. 10, 
1914, 


~ 


20 BULLETIN 453, U. S. DEPARTMENT OF AGRICULTURE. 


Sugar, at first glance an excessively expensive amendment for use _ 
on soil, is not so much more expensive than formaldehyde in the — 
quantities which appear of value in preventing damping-off at three | 
of the nurseries. If some unrefined sugar-bearing substance could | 
be substituted for the table product used in the experiments, itis _ 
entirely possible that for certain soils sugar would become an eco- | 
nomically satisfactory treatment for coniferous seed beds. Zine | 
chlorid also, while probably somewhat more expensive than formal- | 
dehyde, is not so costly as to be economically impossible on soils | 
where it may prove to be the most effective disinfectant. Both of | 
these substances are, however, decidedly more expensive than sul- _ 
phuric acid or copper sulphate. 

The most troublesome thing about the treatment with acid is that 
at some nurseries it is necessary to give treated beds frequent water- 
ings during the germinating period for the protection of the roots of © 
the seedlings against chemical injury. This has been found to be © 
the case in acid plats at three nurseries, and with copper and zinc — 
salts at one nursery, respectively, where these disinfectants have 
given evidence of greatest commercial value. At one of these © 
nurseries (Halsey, Nebr.) figures are available which indicate the — 
cost of the treatment with acid and subsequent watering. The © 
additional labor cost of the seed sowing, due to the use with it of the 
acid application, was furnished by the forest officers. The figures | | 
follow. ; 


Additional cost of seed beds at isles): Nebr., due to acid treatment, per 1,000 square feet } d 
(space occupied by paths excluded). ¥ 


Cost of acid (allowing for freight, drayage, and waste)..........-- LS $1.00 
Additional labor in seed sowing, due to application of acid...............---- | 
Labor cost of extra waterings required by acid beds during germinating period. 2.70 
Depreciation of containers for applying acid solution, and increased supervisory 

cost (estimated), not to exceed .....5...2--...6--+2+-.ne = 5 See 


Total charge against treatment... 2.45.02 +240. oe oe 5.00 


The above figures were obtained in 1912. Subsequent changes in ~ 
nursery practice have probably changed the costs, but no later fig- 
ures are available. 3 

This cost of $5 per 1,000 square feet, or one-half cent per square © 
foot of seed bed, would seem very high if put on an acreage basis. — 
For extensive farming operations it would, of course, be excessive. 
But because of the very high cost of coniferous seed and the very small — 
area on which the seed-bed operations of even a large nursery are — 
usually concentrated, this cost is easily offset by even a slight increase 
in the stand of seedlings secured. -The actual cost of production of — 
seedlings is seldom less than 50 cents per thousand by the end of the 
first growing season. ‘The prices commonly quoted by commercial 
nurseries for seedlings of most species which have remained in the 


DAMPING-OFF OF CONIFEROUS SEEDLINGS. 21 


- 


sced bed for a second year run from four to ten times this figure. If 
the minimum stand commonly desired, 1. e., 100 seedlings per square 
foot, is obtained on untreated beds, an mince in stand of only 20 
er cent will mean an increased production of 20,000 seedlings, of a 
minimum value of $10 for the 1,000 square feet taken as a unit. 
Even in this minimum case, therefore, the treatment may be con- 
sidered to have paid for itself twice over. The ordinary: net results 
should be still more favorable, for the following reasons: 

(1) At nurseries where acid or copper sulphate can be used without especially 
frequent watering the cost of the treatment will be less than at Halsey. At only 
one other nursery has it been found necessary to water the treated beds as much as 
at Halsey. 

(2) The average increase in stand resulting from the treatment is much greater 
than the 20 per cent used in the preceding calculations. Figures based on exact 
counts for two or more seasons are available from five localities (Halsey, the Kansas 
sand hills, Garden City, Fort Bayard, and Monument). The average increase in stand 
resulting from the best treatments at all of these nurseries is exactly 100 per cent. 

(3) An additional advantage, of greater value than the average increase in stand, 
is the stabilization of output through the prevention of damping-off epidemics. 

(4) A further advantage is the development of more uniform stands in the beds by 
the prevention of damping-off patches. 

(5) In addition to the advantages from increased stands and decreased damping-off, 
disinfectant treatment often has incidental results in the way of weed control or of 
increased growth of the conifers which may by themselves more than pay all costs 
connected with the treatment. These secondary advantages are discussed in the 
following paragraphs. 


SECONDARY ADVANTAGES FROM DISINFECTANT TREATMENTS. 


STIMULATION OF GERMINATION CAUSED BY DISINFECTANTS. 


‘It is common and, in fact, almost invariable with all of the disinfect- 
ant treatments which have been successfully used to find a higher ger- 

mination percentage in the treated plats than in the controls. In 
_ some cases this increase in germination (or, more accurately speak- 
‘ing, in the number of seedlings which appear above the soil surface) is 
very large. Whole groups of treated plats have in some cases given 
an apparent germination percentage three times that prevailing in 
the untreated plats in the same group. While such large increases 
are not common, it is a very frequent thing for the advantage in 
increased germination to be greater than that resulting from the 
control of damping-off after germination. (Compare the first and 
second columns under the head of ‘‘Relative results’ in Tables I 
and II.) Such increases are mainly due to the control of parasites 
by the treatments; in the untreated plats Pythium and Rhizoctonia 
‘sll many seedlings or sprouting seeds before they break through the 
‘soil cover. However, in some cases at least, disinfectants, by direct 
action or by their effect on the soil, appear to cause seed to germinate 
which would otherwise have remained dormant. The advantage 
from this apparent stimulation of dormant seed can not be quanti- 


-> a 
\ Faas? 
+ 


4 


22 BULLETIN 453, U. S. DEPARTMENT OF AGRICULTURE. > 


tatively separated from the advantage due to the control of parasites. 
The sum of the results of the treatments in stimulating germination, — 
protecting the germinating seed from parasites, and in preventing — 
damping-off are all cumulatively expressed by the increase in final — 
stand in the treated over the untreated plats at the end of the season. — 


se, 


INCREASED SIZE OF SEEDLINGS CAUSED BY DISINFECTANTS. 


At three of the nurseries where experiments were conducted for | 
several seasons if was found that there was a distinct Increase in the ; 
size of pine seedlings as a result of treatment with sulphuric acid. © 
Immediately after the seedlings come up, the only effect, when there ~ Ei 
is a noticeable effect, is a decreased growth rate in the acid plats. 
This effect later disappears, and during the latter part of the season — 
the seedlings normally grow faster in the acid plats than in the con- — 
trols or in plats.treated with most other disinfectants. Atthe nursery — 
at Halsey during 1912 and 1913, seedlings were measured in five © 
experimental series, three of jack pine, one of western yellow pine, 
and one of Norway pine. The average of all five shows that the acid © 
caused an increase in height of 37 per cent. z 

At the nurseries in the Kansas sand hills and at Garden City acid 
had a much more surprising effect. The results with western yellow 
pine indicated a moderate increase in the first season’s growth, im 
agreement with the Halsey results, this increase being still distinctly 
noticeable, at least at the sand-hill nursery, at the end of the second 3 
year’s growth. But with jack pine at these nurseries unexpectedly 
large increases were secured. At both nurseries jack pine ordinarily 
makes a slow growth during the first season. In plats sown in Novem- — 
ber, 1912, and treated with sulphuric acid early the following spring, 
the average height of jack pine after a year’s growth was found to be ~ 
more than three times that of the seedlings in the untreated plats. 
The effect of acid treatment on the seedlings at the Garden City 
nursery is shown in Plate II, figure 1. At the Kansas sand-hill nurs- — 
ery, root systems as well as tops were examined. The increase in — 
root development appeared entirely commensurate with the increased — 
size of the tops. The air-dry weight of the tops at the sand-hill 
nursery was 74 times as great in these acid plats as in the untreated — 
plats. | 
It is not to be expected that the acid will result in increased growth 
of any species in all soils, as the effect on growth is apparently due : 
not to direct stimulation Of the conifers, but rather to the effect of — 
the acid on the soil. It is interesting to note that the only great — 
increases in growth have been found at the nurseries where the soil 
water contained the largest quantities of acid carbonates. 

The economic value ae a smoderate increase in growth, such as 
is secured at Halsey, depends largely on the system of handling stock. | 
If the seedlings are to be held in the seed bed for two years an increase — 

= ey. 


DAMPING-OFF OF CONIFEROUS SEEDLINGS. 23 


in the first season’s growth is not very important. If, however, it is 
desired to transplant the stock at the end of the first season the 
increase in size due to acid, at least in the jack pine, which is ordi- 
narily most helped, may mean the difference between success and 
failure. In a case of great increase in size, such as was secured by 
the acid treatment of jack pine at the two nurseries in Kansas, the 
economic results are more positive. It was entirely impossible to 
raise 1-year-old stock large enough to transplant without the use of 
acid. With the acid treatment i-year-old seedlings were produced 
which appeared to be in every way the equal of untreated 2-year-old 
stock for transplanting purposes. The time and expense involved in 
holding the stock for a second year in the seed beds were avoided. 
At the Garden City nursery the advantage went even farther than that. 
The seedlings in the untreated beds were so small that they could 
not withstand winterkilling and were practically all killed before the 
second growing season. ‘The seedlings in the acid plats immediately 
adjacent came through the winter practically without loss. While, 
as already stated, the acid proved ineffective at this nursery so far as 
the control of damping-off is concerned, on account of the carbonates 
present in the soil, its effect on growth and the resultant freedom from 
winter loss alone positively indicated its use on jack-pine beds in 
combination with the toxic salts found most valuable for damping-off 


control. 
h WEED CONTROL BY DISINFECTANTS. 


At the nurseries where weeds are troublesome in the seed beds the 
effect of the disinfectants on the weeds is probably the most important 
of the secondary results of the treatment. The plants commonly 
occurring as weeds seem on the whole much more sensitive to acids 
and to copper and zinc salts than do the conifers. The result is that 
treatments so worked out as to be entirely harmless to the coniferous 
seedlings in the beds are found at a number of nurseries to keep the 
beds almost entirely free from weeds during the first three or four 
weeks after the germination of the conifers. This is just the time 
when most weeds can be expected to appear in the untreated beds 
and when the delicacy of the young conifers makes it difficult to do 
_ even hand weeding without breaking or pulling up many of the seed- 
“lings. The economic value of this weed-control feature varies with 
_.different nurseries. At some places the efficiency with which weeds 
are controlled is less than at others. At some places weeds are not 
_ numerous enough to make weed control a consideration of any very 
_ great importance. The only place at which an attempt has been 
_ made to reduce to a dollars-and-cents basis the value of the weed- 
controlling effect of a damping-off control treatment is at Halsey, 
Nebr. Approximate figures obtained from forest officers indicate that 
_ the entire cost of the hand weeding required during the seasons consid- 


24 BULLETIN 453, U. S. DEPARTMENT OF AGRICULTURE. 


ered was approximately $7.60 per 1,000 square feet; that for the season 


of 1912 the cost in the acid beds was $5.40 less than in the untreated 


beds; and in 1913, $5.20 less. This saving in cost of weeding exceeds 
the entire cost of the acid treatment as estimated during the first of 
these years. While the net value of weed control will not be as great 
as this in all seasons or at all nurseries, it appears that at several of 
the nurseries where tests have been carried on the benefit from weed 
control (Pl. I, fig. 2) or from increased growth of the seedlings, or 
from both of these effects combined, will be sufficient to more than 
justify the treatment. In such cases the control of damping-off 
secured by the treatments will be clear gain. It is especially inter- 
esting to note that in the seed beds of the Feather River Forest 
Experiment Station (California) a light sulphuric-acid treatment is in 
regular-use simply on account of its value as a weed killer, entirely 
irrespective of any effect on damping-off. 


CONCLUSIONS AS TO SOIL DISINFECTANTS. 


The results listed in Table III indicate the complexity of the 
problem of soil treatment to control damping-off parasites. Itis 
at once evident that a single season’s experiments conducted on a 
single soil do not furnish a basis on which it is safe to make recom- 
mendations for general use. It furthermore appears that even after 
as extensive experiments as are here reported, it is not possible to 
prescribe any one treatment which will be safe and effective at all 
nurseries. Heat, the disinfecting agent most commonly employed 
by workers with truck soils, has proved inferior to other methods at all 
of the nurseries at which it has been tried. Sulphur, which is re- 
ported to have given excellent results against certain root diseases of 
other plants, has on the whole given disappointing results in pine 
seed beds. Formaldehyde, sulphuric acid, copper sulphate, and zinc 
chlorid, the four most generally satisfactory substances, have each 
failed at one or more nurseries. Especially at nurseries where no 
adequate watering system has been installed the frequent watering 
which beds treated with acid or with copper and zinc salts sometimes 
require means considerable trouble and expense. 

However, after all these difficulties and drawbacks have been con- 
sidered, analysis of the results indicates that it will be practicable to — 
control damping-off by some soil treatment at any nursery where it ¥ 
is troublesome. The first part of Table III, containing results at the 
seven nurseries where repeated tests have been made, is, of course, 
the most important. At all of these nurseries soil treatment has 
proved successful. It is significant that at all but one of these seven 
sulphuric acid has proved successful. The acid failed at the seventh 
nursery only because of the high carbonate content of the soil, a con- 
dition rarely found at coniferous nurseries. At this seventh nursery 


DAMPING-OFF OF CONIFEROUS SEEDLINGS. 25 


’ the cheap and simple copper-sulphate treatment proved entirely sat- 
-isfactory, with the alternative of zinc chlorid in case the copper salt 
should ultimately prove in any way unsatisfactory. At four of the 
seven, all that appears necessary to be done is to apply the disin- 
fectant, and thereafter let the beds take care of themselves. Al- 
though specially frequent watering is required during the germinating 
season by treated beds at the other three nurseries, the cost of this, 
as has been shown for Halsey, is not excessive, and the amount of 
extra watering required to protect the germinating seedlings at the 
- remaining two nurseries is less than at Halsey. 

At the localities considered in the last part of the table, where the 
tests have been mainly or entirely limited to a smgle season, some 
facts of interest have been developed, though at none of them have 
the best control methods been definitely determined. At Dundee 
and Cass Lake a sufficient number of independent series of tests were 
made to show without doubt that some one of the treatments which 
resulted well will be found satisfactory for regular use. At most of 
the other nurseries in this second division the tests have been 
preliminary in character and are only indicative. At 13 of the 
14 localities listed in the second part of the table, the results of 
the tests indicated the value of one or more of the treatments 
tested. At 9 of these 13 the indications were that the disease 
could be controlled by a treatment which would not make neces- 
sary any special watering of the beds. At the one nursery where no 
results were obtained (Pocatello) sulphuric acid was the only substance 
tested under proper watering conditions, and its failure is easily ex- 
plained by the presence of soil carbonates. 

Considering separately the soil treatments employed, it appears 
that there are four reasonably promising disinfectants for use on 
coniferous seed beds. The writers have experimented with approxi- 
mately 50 different substances, alone or in combination, in the 
treatment of seed beds, and these tests, in conjunction with the re- 
sults of the writers and of others which are summarized in Table ITI, 
indicate that the most generally satisfactory substances for such use 
are sulphuric acid, copper sulphate, zinc chlorid, and formaldehyde, 
of which the acid is the most promising. 

The use of sulphuric acid has been reported at 20 different 
localities. At 17 of these it has given indications of value. Its 
failure at Pocatello and Garden City is merely an indication that 
it will not succeed in the presence of large quantities of soil car- 
bonates. At Glenview, Ill., the tests were very prelimmary and 
therefore not sufficient to show that it was valueless. It has become 
_ established as a regular part of nursery practice at all nurseries where 
it has been repeatedly tested, with the exception noted of the one 
where the soil contained carbonates. At several nurseries in the 


26 BULLETIN 453, U. §. DEPARTMENT OF AGRICULTURE. 


Middle West, where the acid in single-season tests did not give as. 
good results as other substances, there is reason to believe that the — 
results of the acid treatment will be much better in normal seasons, — 
The acid has to recommend it, in addition to its effectiveness against 
damping-off, the elements of cheapness, efficiency in killing weeds, ~ 
and in many places of causing an increased growth of the conifers. 
Copper sulphate, tested at 11 different places, gave no indica- 
tions of value at three of them and very doubtful indications at the — 
fourth. At-the others it gave more or less indication of value, reaching 


the stage of regular nursery use at one nursery and at two others giving 
better results than the acid in single-season tests. Copper-sulphate 


treatment costs about the same as treatment with acid and is nearly ~ 
or quite as effective in killing weeds, but has not been observed to 
result in any marked increase in growth of the conifers. 


Data as to the value of zine chlorid were secured from ten nur- — | 


series. Atone of these it failed. At three others the tests were very 
preliminary, and while value was indicated the extent of value was 
not determined. At four it indicated value, but to a less extent 
than other treatments used. At the remaining two it indicated 
sufficient value to rank as a successful treatment. At both of the 
nurseries where it has been given repeated tests it has proved as 
good as any other treatment. ‘At both of these, however, it has not 
been shown to be decidedly better than cheaper treatments (copper 
sulphate at Garden City and sulphuric acid at Fort Bayard), and 


therefore is not likely to replace them in regular use. Like copper — i 


sulphate, it kills weeds in addition to decreasing damping-off and 
has not been observed to cause increased growth of the conifers. 
The relatively high cost of this disinfectant, approximately one-half 
cent per square foot on heavy soils for material alone, is a point 
against it. Both copper sulphate and zinc chlorid cause injury to 
pines on some soils where acid seems entirely harmless. This means 
that their use will at most places necessitate more watering during 
the germinating period than is necessary when acid is used. 

Data as to the value of formaldehyde im controlling damping-off 
have been secured from 12 places. At two of these it has failed. 
At another it has indicated value; extent undetermined. At five 
others it has indicated less value than sulphuric acid, while at the 
four remaining places it has been reported as successful. It also 
kills weeds, has little effect on the growth of pmes, and has the 
advantage of never making necessary any extra watering in treated 
plats. The points against it, in addition to its inferior efficiency in 
controlling damping-off at many nurseries, are its high cost and its 
tendency to kill seed if applied at or near the time of sowing. It4is 


1 At Dundee, formaldehyde alone was considered a failure, as the only successful formaldehyde plats 


were those also treated with zinc chlorid. 


* DAMPING-OFF OF CONIFEROUS SEEDLINGS. aT 


necessary to treat beds some time before sowing, this period varying 
from two days to two weeks in different soils. The generally pre- 
scribed practice of covering the beds to prevent reinfection or pre-. 
mature evaporation of the formaldehyde during this period is 
troublesome and expensive. Further tests may prove it unnecessary. 
In considering disinfectants, the ultimate as well as the immedi- 
ate results should be taken into account. No data are at hand to 
show the effects of repeated treatments of soil with toxic salts or 
formaldehyde. The effects of single treatments seem to be purely 
temporary. Treatments of one-eighth and three-sixteenths ounce 
of copper sulphate per square foot (equivalent to 341 and 511 pounds 
per acre, respectively), which are expected to be quite sufficient for 
use against damping-off at most nurseries, involve additions of only 


_ one-sixth and one-fourth, respectively, of the amount which has 


been used in single treatments at Garden City without any notice- 
able permanent effect. Sulphuric acid might ultimately bring about 
an acid condition of the soil if used repeatedly, but this could be 
easily remedied at any time by the addition of lime. The only 
possible bad effect of continued use of the acid would therefore be 
an accumulation of sulphates. The sulphur added in a treatment of 
three-sixteenths fluid ounce of acid per square foot would be, roughly, 
300 pounds per acre. If repeated every year, this would, of course, 
mean a considerable change in sulphur content. However, it would 
be a very rare thing for a treatment to be applied two consecutive 
_ years on the same soil, and where rotation is practiced five or six 
years commonly elapse between the growing of two crops of seed- 
lings of susceptible species on the same soil. This minimizes the 
likelihood of any bad cumulative effect by the treatments. 

The comparison of the four disinfectants considered in the fore- 


- going paragraphs does not make possible a final statement as to 


their relative value. At most of the localities listed in Table III there 
have not been enough tests to give conclusive results. It is believed 
- from the somewhat incomplete evidence secured that at most nur- 
series soil treatment with sulphuric acid will be found a satisfactory 
and probably the most satisfactory means of decreasing damping- 
off and that where it is not satisfactory success can be secured with 
some one of the other disinfectants—copper sulphate, zine chlorid, 
_ or formaldehyde. } 

It is, of course, recognized that the treatments so far devised are 
not as simple and effective as are desired. Further tests of these 
disinfectants and of numerous others are under way. The problem 
of damping-off control is also being attacked from other directions 
than that of simple soil disinfection. It is hoped that a single disin- 
fection method may be found which can be used on any soil and which 
will not require any unusual precautions against chemical injury; or, 
failing this, that some less direct procedure against the parasites 


28 BULLETIN 453, U. S. DEPARTMENT OF AGRICULTURE. 


will be found satisfactory. The securing of final results along these 
lines will of necessity require several years’ experimenting, because 
of the differences between different soils and the number of species 
of parasites and of conifers which have to be considered. Meantime, 
the foregoing results are published to enable nurserymen to make use 
of the experience already gained. Under the following heading are 
outlined a number of treatments, at least one of which should be 
found successful and profitable at any coniferous nursery where — 
damping-off is prevalent. 


SOIL TREATMENTS RECOMMENDED. 


No treatments can be guaranteed as either safe or effective on all _ 
soils. However, it is nearly certain that for any nursery at least one 
of the following will be found successful. It is therefore recom-— 
mended that any nurseryman who has serious losses from damping- 
off test some of these treatments on a small scale until he finds which — 
one is best suited to his conditions. At least two successful tests — 
should be made before a treatment is judged safe for large-scale use. 


Treatments for heavy soils. 


1. Sulphuric acid, three-sixteenths fluid ounce per square foot of bed, dissolved in 
from | to 2 pints “ water per square foot of bed and applied immediately after the 
seed is sown and covered. 

2. Same as treatment 1, but use one-fourth ounce acid per square foot. | 

3. Copper sulphate, one-eighth avoirdupois ounce per square foot, dissolved in water _ 
and applied immediately after the seed is sown and covered. 

4. Same as treatment 3, but use three-sixteenths ounce per square foot. ry 
5. Zine chlorid, one-half ounce per square foot, dissolved in water and applied — 
immediately after the seed is sown and covered. 

6. Formaldehyde, one-half fluid ounce per square foot, dissolved in water and — 
applied 10 days before the seed issown. Keep the bed covered with paper, tarpaulin, 
or tight shade frames during these 10 days. Do not spade up formaldehyde beds after 
treatment. If necessary to cover the seed with soil from outside of the plat, which 
has not been treated, use subsoil just dug up from at least 1 foot below the surface. 

7. Same as treatment 6, but apply the treatment only three days before sowing and 
do not cover with paper. 

8. Air-slaked lime, one-half avoirdupois ounce per square foot, applied dry and 
raked into upper 3 inches of soil just before sowing. (If hydrated limes is used, three- 
eighths ounce per square foot will be sufficient.) Immediately after seed is sown and 
covered apply three-tenths ounce of sulphuric acid per square foot, dissolved in water. 

9. Same as treatment 3, but use one-fourth ounce per square foot. 


In dissolving disinfectants, use sufficient water to make from 1 to 2 
pints of solution per square foot. ‘Two pints should be used if the 
soil is dry; 1 pint is sufficient when the soil is wet. 


Treatments for sandy soils. 


1. Sulphuric acid, one-eighth fluid ounce per square foot, dissolved in water and 
applied immediately after the seed is sown and covered. 
2. Same as treatment 1, but three-sixteenths ounce per square foot. 
e 


DAMPING-OFF OF CONIFEROUS SEEDLINGS. 29 


3. Copper sulphate, one-tenth avoirdupois ounce per square foot, dissolved in water 
and applied immediately after the seed is sown and covered. 

4. Same as treatment 3, but one-sixth ounce per square foot. 

5. Zine chlorid, five-sixteenths avoirdupois ounce per square foot, dissolved in water 
and applied immediately after the seed is sown and covered. 

6. Formaldehyde, five-sixteenths fluid ounce per square foot, dissolved in water and 
_ applied 10 days before seed is sown. Keep the bed covered with paper or tarpaulin 
during these 10 days. Do not spade up formaldehyde beds after treatment. If 
necessary to cover the seed with soil from outside of the plat, use subsoil just dug up 
from at least 1 foot below the surface. 

7. Same as treatment 6, but apply only three days before seed sowing and do not 
cover beds with paper. 

8. Air-slaked lime, three-eighths avoirdupois ounce per square foot, applied dry 
and raked into the upper 3 inches of soil just before sowing. (If hydrated lime is 
used, three-tenths ounce per square foot will be sufficient.) Immediately after the 
seed is sown and covered, apply one-fifth ounce of sulphuric acid per square foot, 
dissolved in water. 


In dissolving disinfectants for sandy soils, use sufficient water to 
make from 1 to 14 pints of solution per square foot. One and one- 
half pints should be used if the soil is dry; 1 pint is sufficient if the 
soil is already wet. 


GENERAL DIRECTIONS FOR TREATMENTS. 


Commercial or technical grades of all the disinfectants are satisfac- 
tory. The sulphuric acid purchased should be concentrated, having 
a specific gravity of at least 1.82, while the formaldehyde solution, or 
“formalin’’ as it is sometimes called, should be the strongest obtain- 
able, so-called 40 per cent solution, containing 37 per cent by weight. 
All disinfectants should be kept from the air as much as possible, as 
they change in strength if exposed. Copper sulphate requires the 
least care in this respect. Acid should be dissolved by pouring it into 
the water—never by the reverse process, Copper sulphate is quickest 
dissolved by putting it in a burlap sack and hanging it in the water 
just below the surface. Both of these solutions are corrosive to metal 
and should be handled only in wooden or earthenware containers and 
applied with sprinklers which have been coated inside with hot 
paraffin. Acid is also hard on the hands and clothes. Men who use 
it on a large scale are very careful to keep their shoes heavily greased. 
Canvas gloves treated with hot paraffin or with a mixture of paraffin 
and a lighter grease, such as vaseline or lard, should be a valuable pro- 
tection for the hands. The charring of wooden containers used in 
-tImaking up dilute acid solutions probably can be largely prevented by 
washing them out well with water containing washing soda before they 
preserves. Shave off some of the paraffin into the sprinkler, and heat the sprinkler till all the paraffin is 
melted. Then turn the sprinkler around so that the liquid paraffin runs over the entire inside surface 
and finally pour what is left of the paraffin out through the spout. The whole can should be hot during 


_ the process, so that the paraffin will leave a thin coating; a thick coating cracks off too easily. The holes 
in the sprinkler head will have to be cleaned out with a pin or toothpick after the paraffin has hardened. 


30 BULLETIN 453, U. S. DEPARTMENT OF AGRICULTURE. 


are put away at the close of work. A coating of linseed oil, very 
thoroughly dried, should also prevent the charring of wood. Acid ~ 
which gets on the hands does no harm if washed off at once with water. _ 
In applying treatments on a large scale the sprinklers used should — 
have the holes in the rose or sprinkler head enlarged, to permit | 
faster work. | 

In trying out the treatments in the foregoing lists, Nos. 1 and 2, 
the most promising, should be tested first. If both fail, the other 
treatments should be tried. If the acid solutions 
Not cause the soil to effervesce, some of the other treat- | 
ments should be tried at once, as on such a soil the — 
acid is likely to fail. | 

The treatments should be applied to small plats — 
which are intermingled with untreated plats for com- — 


treated. 


Treatment 


No. 1. parison. For test plats, 3 by 4 feet has been founda ~ 


convenient size. Good results can be obtained with 4 
Tieatment even smaller areas than this, but all plats should be 

2 : 2 = | 
hg the writers have found satisfactory is shown in figurel. — 
The seed for each plat, treated and untreated, should 


Not 


at least 2 feet wide. An arrangement of plats which + 


be measured out separately, so that all plats will get © 


treated, equal quantities of seed. Then the number of seed- | 


—__————] lings living on each plat at the end of the season will — 

Treatment show which treatment is most valuable. In watering, | 
shading, and in every other way treated plats should | 
be handled just like the untreated beds, to make the 
test a fair one. i 

As soon as the seedlings begin to drop their seed ~ 
No. 4. coats, plats treated with acid, copper sulphate, or zinc — 
chlorid should be examined for chemical injury to the — 


Bs 


Treatment 


found to occur, two courses will be open: (1) To test 
the same treatment again, watering the treated plats — 
«<——4'---—» thoroughly every day from sowing till germination 
Fic.1.—Suggestea 18 complete; or, (2) to abandon the treatment which 

arrangement of test ¢aysed injury and try to get sufficient control of the © 

nae disease by a weaker treatment or by another dis- 
infectant. Treatments 6, 7, and 8 are inserted especially for use at 


treated. 


roots of the seedlings: If such chemical injury is 


places where acid causes injury and where frequent watering is not | 


practicable; they are reasonably certain not to cause injury to seed- — 
lings under any circumstances. 


1 The method of detecting chemical injury and illustrations of injured and uninjured seedlings have _ 
been given in a previous publication: Hartley, Carl. Injury by disinfectants to seeds and roots in sandy 
soils. U.S. Dept. Agr. Bul. 169, p. 9, pl. 1. 1915. This bulletin can be obtained bysending 5centsin ~ 
coin to the Superintendent of Documents, Government Printing Office, Washington, D. C. 


DAMPING-OFF OF CONIFEROUS SEEDLINGS. spr gee 


SUMMARY. 


(1) By, damping-off is meant the killing of very young seedlings by 
parasitic fungi. It is the most serious difficulty encountered in rais- 
ing coniferous seedlings. | 
(2) To decrease losses from the disease excessive moisture and 
shade should be avoided. Caution must be used in following this 
recommendation or many seedlings may be killed by drought or by 
white-spot injury to the base of the stem. Damping-off can often 
be decreased by putting beds on very sandy soil. Seed should not 
be sown any thicker than necessary. It appears better to sow 
broadcast than in drills. Late fall sowing results in decreased losses 
at some nurseries and is worth trial. Proper attention to all of these 
_ measures will decrease the losses from damping-off, but at most 
nurseries they are not sufficient really to control the disease. 
(3) The addition of lime, wood ashes, and in some cases nitrog- 
enous fertilizers seems to increase damping-off. Soil alkalinity 
appears to favor the disease. No effect has been noted from green 
manures. The use of unrotted stable manure has had very bad 
results; properly rotted manures seem less objectionable. Tankage, 
charcoal, and cane sugar are the only nondisinfectant substances 
which to date have given any hope of disease control. 
(4) Soil disinfection has so far proved the best method of combat- 
ing damping-off. Of many methods tested, treatments with sul- 
phuric acid, copper sulphate, zinc chlorid, and formaldehyde have 
proved the most satisfactory. The disinfectants behave quite differ- 
ently at different nurseries. The results of treatments at many 
different localities are summarized in Table III. The acid has on 
the whole given the best results. Heat disinfection has been only 
_ partly effective. Disinfection by acid or copper sulphate is cheaper 
| than by the other methods commonly recommended. 

(5) In addition to decreasing damping-off after the seedlings come | 
q up, the chemical disinfectants above mentioned, when properly used, 
cause an increase in the apparent germination and are very helpful i in 
‘controlling weeds. This latter effect alone at some nurseries pays 
the entire expense of the treatment. Sulphuric acid has, further- 
more, at some places resulted in marked increases in the lnte-season 
g owth of pines. (See Pl. IT.) 

- (6) In some soils formaldehyde kills dormant seed, and the other 
three most satisfactory disinfectants at some nurseries kill the root 
tips of germinating seedlings. By proper precaution, all such injury 
may be prevented. 

_ (7) The results obtained to date show that it is entirely possible 
and practicable to control damping-off by soil disinfection. Unfortu- 
nately, the varying behavior of disinfectants at different places 


32 - BULLETIN 453, U. S. DEPARTMENT OF AGRICULTURE. 


renders it impossible to recommend any single treatment which will — 
be everywhere successful. Directions are given for simple tests, by — 
which it is believed that any nurseryman can develop a treatment 
that will succeed under his conditions. | a 
(8) Further experiments are being conducted, with the hope of 
discovering either a more generally applicable disinfectant method 
than any of those so far tested or else a means of controlling the 
disease without the use of disinfectants. 


ADDITIONAL COPIES 
OF THIS PUBLICATION MAY BE PROCURED FROM 
THE SUPERINTENDENT OF DOCUMENTS 
GOVERNMENT PRINTING OFFICE 
WASHINGTON, D. C. 
AT 
5 CENTS PER COPY 


V > 


WASHINGTON : GOVERNMENT PRINTING OFFICE : 1918 


UNITED STATES DEPARTMENT OF AGRICULTURE 


%)\, BULLETIN No. 490 (2h 


ANd Contribution from the Bureau of Plant Industry 
. WM. A. TAYLOR, Chief 


Washington, D. C. PROFESSIONAL PAPER. January 18, 1917 


A PRELIMINARY REPORT ON THE OCCURRENCE 
OF WESTERN RED-ROT IN PINUS PONDEROSA. 


By W. H. Lone, 
Forest Pathologist, Office of Investigations in Forest Pathology. 


CONTENTS. 

Page. Page 
U URG IS SOG: 6S gee eee 1 | External signs of western red-rot............. 4 
Description of western red-rot....-.-.......- 1 | Areas examined for western red-rot....-..... 5 
Development of western red-rot in the tree... 2 | Number and kind of trees examined........- 5 
Comparison of western red-rot and true red- Western red-rot in black jack and yellow pine. ih 

Ra eae ile cisiciate be seeclnacie succes 3 | Western red-rot and the rotation for western 
Cause of western red-rot ........-...--------- a Selo Mibes Faerie an tein n ete ag Sa aera 7 
Entrance of western red-rot into living trees. Gt EUAN ore ea Seas oak «cae anna afeietele ailln s 8 
INTRODUCTION. 


In the national forests of Arizona and New Mexico a varying per- 
centage of the trees of western yellow pine (Pinus ponderosa) is 
affected by an undescribed heart-rot, known locally as red-heart, red- 
rot, gray-rot, top-rot, and heart-rot. The amount of this rot present 
_ varies materially with the exposure, slope, and soil on which the 
yellow pine is growing, as well as with the age of the timber itself. 
_ It is the main heart-rot found in western yellow pine in Arizona and 
New Mexico and causes an annual loss of thousands of dollars. 

This heart-rot is here called “ western red-rot” in order to dis- 
tinguish it from the true red-heart or red-rot, a very similar heart- 
rot common in many species of conifers throughout the world. 
True red-rot or ring scale is caused by Trametes pini, while western 
red-rot is produced by an entirely different fungus. 


DESCRIPTION OF WESTERN RED-ROT. 


CROSS-SECTIONAL VIEW. 


Western red-rot may show in the end of a freshly cut log any one 

of the following stages: (1) An early stage, in which the heartwood 

is firm but shows reddish to dark-brown discolored areas. Such 
64936°—17 


2 BULLETIN 490, U. S. DEPARTMENT OF AGRICULTURE. 


areas are often fan shaped and radiate outward from the center of 
the log, like spokes from the hub of a wagon wheel, or they may be 
isolated and occur anywhere in the heartwood. (2) A more ad- 
vanced, or what might be called an intermediate stage, of the rot, in 
which the affected heartwood is whitish or grayish in color and is so 
disintegrated that small pieces can be pulled out. The rotted wood 
consists of soft white strands of cellulose, intermixed with less rotted 
wood particles. The rotten wood in this stage is often so wet and 
soggy that water can be squeezed out of it. The white-rot or gray- 
rot stage is usually in the center of the log and is often surrounded 
by the brownish fanlike areas seen in the first stage of the rot. (3) 
A third or final stage of the rot, in which much of the heartwood 
has been destroyed, leaving the remainder in a very brittle, rotten 
condition, so that it easily crumbles when handled. Im this final 
stage of the rot all of the cellulose has been absorbed by the fungus, 
while the wood particles left are reddish to dark brown in color. © 
This stage sometimes occupies only a small portion of the heartwood 
in the center of the log and may be surrounded by one or both of the 
other stages. | 
LONGITUDINAL-SECTION VIEW. 

In a longitudinal section, as seen in sawed lumber, the different ‘ 
stages of the rot gradually merge into one another. In the place 
where the fungus entered the tree will be found the oldest stage — 
which the rot has reached in that particular lesion. If the entire 
lesion originated from only one center of infection (one dead branch) 
and the rot has been in the tree for many years, then the three stages 
described will probably be represented in the one lesion, which may 
be anywhere from 12 to 20 feet long. There will usually be some 6 
to 10 feet in the center of the log which belong to the second and 
third stages of the rot, while the extremities of the rot lesion will 
consist of the first stage of the rot. 


DEVELOPMENT OF WESTERN RED-ROT IN THE TREE. 


This rot advances nearly as rapidly radially as it does longitu- 
dinally in the heartwood of the affected tree. Its radial development — 
in the wood is rather peculiar. From the central cylinder of the rot, — 
at irregular intervals along its entire length, narrow radial patches 
of rot extend outward toward the sapwood. ‘These radial patches — 
are the fanlike or spokelike discolored areas on the end of the log, 
described under the first stage of the rot. The centers of these radial - 
patches usually consist of whitish delignified tissue, bordered by red- — 
dish to dark-brown areas of heartwood which have not yet been de- 
lignified but are in the early stages of the rot. Often some of the 
cellulose in the center of these patches has been entirely absorbed, — 
leaving small irregular cavities extending to the sapwood. 


“WESTERN RED-ROT IN PINUS PONDEROSA. 3 


From these radial patches the rot spreads in all directions, until 
finally the entire heartwood is involved. In tangential sections 
these radial patches of rot appear as irregular elliptical reddish to 
brown areas with white centers. These areas are two to several 
times longer than broad, with their greatest diameter lying parallel 
with the grain of the wood. There is often a small cavity bordered 
by the unabsorbed remnants of the delignified tissue in the center of 
each rotted area. Usually two to six of these discolored areas are 
grouped together, giving the sawed lumber a very peculiar appear- 
ance. 


COMPARISON OF WESTERN RED-ROT AND TRUE RED-ROT. 


When examining the rot in the end of a freshly cut pine log it 
is often difficult to determine whether it is western red-rot or true 
red-rot. A longitudinal view of the rot, however, usually will settle 
the question beyond any reasonable doubt, since the following con- 
stant characters are then in evidence: (1) True red-rot, or red-heart, 
caused by 7rametes pint, has many small but sharply defined pockets, 
or cavities, in the heartwood, lying parallel to the grain of the wood, 
while western red-rot never has these typical pockets. (2) The 
attacked wood in true red-rot is usually very firm, even in the final 
stage of the rot, while western red-rot in its last stage is much dis- 
integrated and easily crumbles when handled. (3) The mycelium 
of true red-rot when growing in heartwood which is more or less 
exposed to the air is brown, while the mycelium of the western red- 
rot is always white. (4) The attacked heartwood in true red-rot 
never becomes wet and soggy, as it often does in certain stages of 
western red-rot. 


CAUSE OF WESTERN RED-ROT. 


The fungus which causes western red-rot never forms brown, 
_ woody, perennial fruiting bodies on the boles of living affected pine 
_ trees, as Trametes pini does, but forms annual fruiting bodies, which 
are usually developed as white encrusting layers on the under side 
of logs lying on the ground. This fungus is also the main agent in 
rotting the sapwood of the cull logs and large branches of the yellow- 
pine slash. 

The fruiting bodies, or sporophores, of this fungus, as they occur 
in Arizona and New Mexico, are usually resupinate, with a hymenial 
layer consisting of minute tubes or pores. However, fruiting bodies 
have been found which have distinct and well-formed pilei. The 
pileate form of the fungus resembles very closely Polyporus ellisianus 
(Tyromyces ellisianus of Murrill in North American Flora); the 


-iLong, W. H. A new aspect of brush disposal in Arizona and New Mexico. In Proc. 
Soc, Amer. Foresters, v. 10, no. 4, p. 383-398. 1915. 


4 BULLETIN 490, U. S. DEPARTMENT OF AGRICULTURE. 


writer, however, does not wish to call it by this name until the in- 
vestigations now under way as to its identity are completed. 

Lloyd reports a specimen of the same fungus from the State of 
Washington, collected by J. M. Grant,’ and refers it to Polyporus 
ellisianus. The writer (through the kindness of Mr. Lioyd) has been 
able to examine a portion of the collection from Washington, and it 
agrees in all essential characters with the fungus which causes west- 
ern red-rot in Arizona and New Mexico. Concerning the host of the 
Washington specimen Lloyd writes, “There was no note with the 
specimen regarding its host, excepting that it grew on a pine of some 
kind.” 

A sporophore of what is apparently the western red-rot fungus 
has been examined from Idaho. > 

Von Schrenk? in 1903 published a figure of a heart-rot of living 
trees of Pinus ponderosa from the Black Hills Forest Reserve in South 
Dakota, which is typical of the second stage (cross-sectional view) 
of this rot as it occurs in yellow pine in New Mexico and Arizona. 
It is therefore highly probable that this fungus is widely distributed 
throughout the West, both as a saprophyte in slash and dead trees 
and as a heart-rot in living timber. The writer has examined a speci- 
men of the same fungus collected in New Jersey on Pinus sp. and one 
of both fungus and rot from Vermont on P. strobus. 


ENTRANCE OF WESTERN RED-ROT INTO LIVING TREES. 


The western red-rot fungus enters the living tree through dead 
branches in the crown. It first attacks the sapwood of the dead 
branch; then the heartwood. It then travels down the sapwood and 
heartwood of the dead branch into the heartwood of the living tree. 


Once established in the tree, the fungus apparently continues to grow - 


as long as the tree is alive, spreading in all directions, until often the 
heartwood of the entire bole of the tree, as well as that of the large 
branches, is invaded and rendered worthless for lumber. 


EXTERNAL SIGNS OF WESTERN RED-ROT. 


No external signs were found which would absolutely determine 
whether or not a given standing yellow-pine tree was defective. 
Trees having large dead branches intermixed with living limbs and 
ragged and unhealthy looking crowns were often attacked by western 
red-rot. Such defective trees were usually located on very thin soil on 
steep south or east slopes, where growth conditions were very poor. 
However, many trees which showed no recognizable external evi- 
dences of decay were found to have western red-rot when they were 
felled. | 


1ZLloyd, C. G. Mycological writings, v. 4, letter no. 60, p. 4. 1915. 

2 Schrenk, Hermann von, The “ bluing” and the ‘‘ red rot” of the western yellow pine, 
with special reference to the Black Hills forest reserve. U. 8S. Dept. Agr., Bur. Plant 
Indus. Bul. 36, p. 34, 40, pl. 14, fig. 2. 1903. 


WESTERN RED-ROT IN PINUS PONDEROSA. 5 


AREAS EXAMINED FOR WESTERN RED-ROT. 


Before marking an area for cutting it should be determined 
whether the rotation is to be short, medium, or long. Often the 
amount and character of the defect present in the timber will be an 
important factor in determining what rotation is best for the area in 
question, especially in stands of virgin timber. 

In order to throw some light on the presence of defects, especially 
western red-rot, in western yellow pine and its probable influence on 
the rotation period, studies were conducted on certain areas in the 
Santa Fe National Forest where both tie trees and saw timber were 
being cut. The main problem which demanded immediate attention 
was the relative amount of rot present in the black jack on these areas 
compared to that in the yellow pine. The special areas examined 
were located in Cienega, Ocho, Amole, Gallegos, and La Junta 
Canyons and on adjacent mesas, all of which are situated in the 
Cienega ranger district. The data given here were obtained mainly 
from Cienega, Ocho, and Amole Canyons on areas which had been 
cut for hewn ties. A small area near the Cienega ranger station on 
which both ties and saw timber had been cut was also examined for 
rot. The tie trees ranged from 10 to 16 inches, d. b. h., while those 
over these diameters were saw timber. These areas were especially 
suitable for a study of this character, since an unusually large per- 
centage of the black jack (30 to 50 per cent) and nearly all of the 
yellow pine (85 to 100 per cent) were being cut. 

There are two forms of western yellow pine called, respectively, 
black jack and yellow pine. Black jack is the form which this pine 
assumes before it reaches the age of 125 to 150 years.t. During this 
period its bark is blackish to dark brown, with narrow furrows, while 
the yellow-pine form has lighter colored, widely furrowed bark. 


NUMBER AND KIND OF TREES EXAMINED. 


In the vicinity of the Cienega ranger station, 1,691 felled black 
jacks and 547 felled yellow-pine trees were examined for rot. In 
addition to this, all of the trees 4 inches, d. b. h., and over on a 
sample strip 1 chain wide and 140 chains long, located on the mesa 
between Ocho and Cienega Canyons, were tallied by the district 
marking board of the Forest Service, carefully examined, and any 
evidences of disease or defect noted. One hundred and twenty-four 
felled black jacks (10 to 16 inches, d. b. h.) and 16 felled yellow 
pines (12 to 16 inches, d. b. h.) had been cut for hewn ties on this 
sample strip. 

Table I shows the number of sound and defective trees on each 
of the areas examined and in a general way the character of the 


1 Woolsey, T. S., jr. Western yellow pine in Arizona and New Mexico. U. S. Dept. 
Agr., Forest Serv. Bul. 101, 64 p., illus, 4 pl. 1911. 


6 BULLETIN 490, U. S. DEPARTMENT OF AGRICULTURE. _ 


site on which the trees were located. The amount of butt-rot (prob- 4 


ably caused by Polyporus schweinitzii) present on the areas ex- 
amined was so small that it was not included in the table. This ex- 
plains any apparent discrepancy between the sum of the sound and 
defective trees and the total number of trees listed in the table. 


TABLE I.—Data on sound and defective felled trees of black jack and yellow pine. 


Defective trees 
Sound trees. (western red- 
Num- rot). 
Area.| Kind oftimber. ! ber of Remarks. 


Num- Per Num- Per 


ber. cent. ber. cent. 

1 Black jaek..0.% Js. © 210 206 | 98 4 1.9 es ofridge; growth conditions fair, 
Yellow pine......- 20 18 | 90 2 et0 5 mainly black ee " 

Black jack.......-. 294 293 | 99.66 Pt So Ly ower portion o sout east slopes 

2 |\Yellow pine......- 84 73 | 86.9 10 | 11.9 and hed ot canyat, @y ae 

: South and southeast slopes; thin 
Black jack. ...'...-2 126 124 | 98.4 2 1.6 « : 

3 : soil; slopes steep, rocky; growth 
Yellow pine......- 132 87 | 65.9 40 | 30.3 | conditions poor. ae : 
Black jack......... 206 | 193} 93.7 9| 4.3 |JPouth and east slopes, at aor 

4 \\Yellow pine....... 76 57| 75 14| 18.4 sedis steep; growth conditions 

5 Black jack......... 855 836 | 97.7 14 1.6 |\Mesas; soil good; growth conditions 
Yellow pine....... 235 223 | 94.9 8 3.4 good. 

6 Black jack.......:. 124 123 | 99.2 iDidhh. hice eps: sample strip across mesa; 
Yellow pine....... 16 13} 81.25 33 18.75 growth conditions fair. 

Black jack......... 1,815 | 1,775.| 97.8 29] 1.59 
1-6 Yellow pine....... 563 471 | 83.6 mee 13.6 Total for all areas. 
Both kinds....| 2,378 | 2,246] 94.4 106| 4.5 


DISCUSSION OF THE DATA PRESENTED IN TABLE I. 


A study of Table I shows several interesting facts: (1) There is a 
marked difference in the percentage of black jack and of yellow pine 
affected by western red-rot. (2) The site seems to have a decided 
influence on the occurrence of this rot, especially in the yellow pine. 
(3) The variation in the percentage of western red-rot on the dif- 
ferent areas shown in the table is due to several factors, the three most 
prominent ones being the relative proportion of black jack and yellow 
pine which had been cut on each area, the influence of the site on the 
growth of the trees, and the age of the timber. For instance, on area 
No. 3 the percentage of this rot in yellow pine is high, due apparently 
to unfavorable growth conditions and the age of the timber cut. 

Table I should give a fairly accurate idea of the occurrence of west- 
ern red-rot in black jack of merchantable size in this region, since 
1,855 trees of this kind were examined over areas where 30 to 50 per 
cent of the black jack 11 inches, d. b. h., and over had been cut. 
As an indication of the amount of this rot present in the yellow pine, 
Table I is not so conclusive, since, with the exception of areas 3 and 
4, all of the yellow pine shown in the table was of small diameter (12 
to 18 inches, d. b. h.) and was cut for hewn ties only. This means 
that the percentage of trees showing western red-rot in the yellow 
pine on these areas will be greater than is shown in the table, except 


WESTERN RED-ROT IN PINUS PONDEROSA. i 


areas 3 and 4. The older the trees are, the greater the amount of rot 
present, since such trees have had more opportunities for infection 
than younger trees. However, taking the area as a whole, probably 
20 per cent of the yellow- pine trees (exclusive of black jacks) will 
show western red-rot in some portion of the bole. The areas shown 
in this table are mainly covered with black jacks intermixed with only 
a small number of yellow pines. For instance, in the sample strip, 1 
chain wide and 140 chains long, 195 black jacks were marked for cut- 
ting and 1,270 left, a total of 1,465 black jacks 4 inches, d. b. h., and 
over, while 108 yellow pines were marked and 22 left. Of the 1,465 
black jacks present on this area, there were 605 trees of merchantable 
size (10 inches, d. b. h., and over) to only 130 yellow pines. This 
means that on such areas the percentage of western red-rot in the mer- 
chantable timber will be small compared to similar areas where the 
proportion of yellow pine is greater than that of black jack. 


WESTERN RED-ROT IN BLACK JACK AND YELLOW PINE. 


The percentage of western red-rot in black jack for all the areas is 
very small, since only 29 trees out of 1,815 (1.59 per cent) showed this 
rot, while in yellow pine it was much greater, 77 trees out of 563 (13.6 
per cent) being infected. Even then, this percentage is not high when 
compared with some other areas in Arizona and New Mexico. For 
instance, on certain sale areas on the Upper Pecos River, 70 to 95 per 
cent of the yellow-pine trees were attacked by western red-rot. Since 
this rot enters mainly through dead branches it is easily seen why 
fewer black jacks are attacked by it than yellow pines. The total 
percentage of trees attacked by western red-rot, both bla¢k jack and 
yellow pine, is only 4.5 per cent for all the areas shown in Table I. 

Of the black jacks infected with western red-rot, nearly all were 
suppressed or grown under very unfavorable conditions. This indi- 
cates that all such trees should be marked for cutting when possible, 
not only on account of their susceptibility to this rot, but also be- 
cause they will never make strong, thrifty trees. When the soil is 
deep and capable of producing vigorous growth in the trees, western 
red-rot is present only in a small degree unless the trees are very 
old and overmature. Such soil conditions are found on many of 
the mesas and near the bottoms of small canyons. There is always a 
marked increase in the amount of western red-rot in yellow pine 
erowing on very steep slopes and on poor, thin soil. 


ee ae RN RED-ROT AND THE ROTATION FOR WESTERN YELLOW 
PINE. 


As to the relative efficiency of a long rotation and of a medium or 
short rotation period in finally eliminating this rot from the forest, 
the answer is very evident, judging from the viewpoint of the rot 


8 BULLETIN 490, U. S. DEPARTMENT OF AGRICULTURE. 


alone. Table I clearly shows that during the black-jack period the 
trees are practically free from this rot, but as they grow older the 
increasing number of dead branches makes them more open to the 
attacks of this fungus; that is, after the trees enter the yellow-pine 
stage of their growth they are more and more subject to infection by 
heart-rotting fungi. 

In the Cienega ranger district western yellow-pine trees up to 125 
or 150 years old (the black-jack period) are rarely attacked by 
western red-rot, for the reasons previously given, while trees over 
200 years old show a much higher percentage of rot than the younger 
trees (black jack). Any system of cutting that will take out most 
of the older trees (yellow pine) and many of the larger black jacks, 
as well as all suppressed trees, will do much to rid the future forest 
of this serious heart-rot. It also follows that a short rotation will 
be better for the future health of the forest so far as heart-rots are 
concerned. It is a fundamental fact that the older a tree is, the 
more liable it is to be attacked by heart-rotting fungi. 


SUMMARY. 


(1) A varying percentage of western yellow pines in Arizona and 
New Mexico is affected by a serious heart-rot called in this bulletin 
western red-rot. 

(2) Western red-rot has three stages in its development: (a) An 
initial stage, in which the affected heartwood is firm but shows red- 
dish to dark-brown discolored areas; (6) an intermediate stage, in 
which the diseased heartwood is whitish or gray in color and more 
or less delignified; (¢) a final stage, in which much of the heartwood 
has disappeared, owing to the absorption of the delignified por- 
tions, while the wood particles left are brittle and crumble easily 
when handled. 

(3) Western red-rot attacks both the sapwood and the heartwood 
of dead branches on living trees. It then travels down the dead 
branches into the heartwood of the living tree. 

(4) No constant external signs were found which would abso- 
lutely determine whether or not a given living yellow-pine tree was 
attacked by western red-rot. However, trees growing on very thin 
soil on steep south or east slopes where growth conditions are very 
poor have a higher percentage of this rot than yellow pines situated 
where the growth conditions are good. 

(5) Of the 1,815 black jacks examined for western red-rot, only 
29, or 1.59 per cent, had this rot, while out of 563 yellow pines ex- 
amined, 77, or 13.6 per cent, were attacked by this rot. 

(6) So far as heart-rots are concerned a short rotation is better 
for the future health of the forest than a long one. 


WASHINGTON : GOVERNMENT PRINTING OFFICE : 1917 


UNITED STATES DEPARTMENT OF AGRICULTURE 


Contribution from the Bureau of Plant Industry 
WM. A. TAYLOR, Chief 


Washington, D. C. PROFESSIONAL PAPER February 16, 1917 


INVESTIGATIONS OF THE ROTTING OF SLASH IN 
ARKANSAS.’ 


By W. H. Lone, 
Forest Pathologist, Office of Investigations in Forest Pathology. 


CONTENTS. 

Page Page 
LICHE CCG OID = 6 oo ae aD OSE nESE: Eee een 1 | The growth of wood-rotting fungi.............. 9 
Methods of brush disposal................--..- 2 | Why brush in the center of the pile does not rot.. 10 
\Meiiteon UeSi GS! ee hh ea a 35in Generali discussionis+-c-- on. - 3 cu/: sscee eae il 
Black-oak and post-oak slash..........-...-.-- de. Wenn. 5 Se eee at es. ah ee as ele 14 
Bnortieni-pime slash...-...............2:.::.--. fed 

INTRODUCTION. 


Two very important factors must be considered in administering 
timber-sale areas, viz, the conservation of the present second growth 
and the leaving of the area in the best possible condition for future 
reproduction. The particular method of brush disposal over such 
areas is therefore of importance from the reproduction viewpoint. 
In the semiarid regions of the Southwest the dominant factor gov- 
erning reproduction is the obtaining and conserving of sufficient 
- moisture to germinate the seeds and to carry the seedlings over the 

first four or five years of their existence. In the forests of Arkansas 

_ the conservation of the moisture is of minor importance, since the 
annual rainfall is usually sufficient to supply all of the moisture 
necessary for the germination of the seed and for the continued 
growth of the seedlings. 

Fire is a very important factor from a reproduction viewpoint 
in the National Forests of Arkansas. The Ozark National Forest 
consists almost exclusively of mixed stands of timber in which hard- 


1The writer is under obligations to Mrs. Flora W. Patterson and Drs. E. A. Burt, 
C. L. Shear, and W. A. Murrill for assistance rendered in identifying many of the fungi 
mentioned in this bulletin. 


66552°—Bull. 496—17——-1 


>, BULLETIN 496, U. S. DEPARTMENT OF AGRICULTURE. 


wood trees usually predominate, while the Arkansas National Forest — 
is dominated by pines. The annual leaf fall from the deciduous 
trees accumulating year after year on the ground and the large 
growth of underbrush present constitute a perpetual fire menace. 
Even on areas in these two forests where shortleaf pine (Pinus 
echinata)* is being logged there are usually enough deciduous trees — 
and underbrush present to make a ground litter from the fallen 
leaves, to which must be added the usual leaf litter found under pine 
trees. 

The method of brush disposal that will give to the reproduction 
over these areas protection from fire and yet leave as much as pos- — 
sible of the forest litter, leaves, twigs, etc., on the ground to rot, 
thereby adding fertility to the soil and protecting it against exces- — 
sive erosion by restraining the run-off, is the one that should be 
adopted. The best method of brush disposal when the slash remains 
on logged areas is that which leaves the brush in such a condition 
that it will rot most rapidly, thus removing as soon as possible the 
fire menace from this source. 


METHODS OF BRUSH DISPOSAL. 


The three methods of brush disposal discussed in this bulletin are 
(1) pulling, (2) piling, and (3) scattering. 

By “pulling” is meant that the brush in the tops of the felled 
trees is not lopped, but is left exactly as the tree tops fall except when 
they fall on or near reproduction. When brush is too close to repro- 
duction it is pulled away from the young trees and merchantable 
timber, to decrease the danger from possible fire; hence the term 
“ pulled brush.” 

The terms “ piling” and “scattering” are self-explanatory. ; 

Piling is the usual method of brush disposal followed in the ~ 
National Forests of Arkansas. However, a few Forest Service areas ~ 
were examined where the brush had been scattered as an experiment. 
In this State pulling the brush has not yet been practiced on Govern- 
- ment sales, but on alienated or patented lands all of the brush in © 
the tops of the felled trees is generally left as it falls. This is really — 
a combination of “ pulling” and “scattering,” since the tops are left — 
unlopped while the branches cut from the merchantable portion of — 
the bole are scattered on the ground. The character and rate of 
rotting of the brush left on these private areas will therefore be the — 
same as when the brush is pulled or scattered. < 

This bulletin deals specifically with the rapidity with which the ~ 
brush rots and with the fungi causing this rotting under each of — 


list of the forest trees of the United States, their names and ranges. U. 8S. Dept. Agr., 
Div. Forestry Bul. 17, 144 p. 1898.) . a 


INVESTIGATIONS OF THE ROTTING OF SLASH IN ARKANSAS. 3 


these methods. It will be necessary in discussing the various methods 
of brush disposal to take into consideration the types of timber being 
cut. In the Ozark National Forest the main timber is white oak 
(Quercus alba) intermixed with black oak (Q. velutina), post oak, 
(Q. stellata), and several other species of minor importance, while on 
certain areas some shortleaf pine is found. In the Arkansas National 
Forest the bulk of the timber to be logged is shortleaf pine. 

The investigations of the rotting of slash in Arkansas were car- 
ried on in the Arkansas and Ozark National Forests on areas which 
had been logged from 1 to 10 years. All of the areas examined which 
had been logged for more than five years were on private or patented 
lands, but located within these National Forests. The conclusions 
reached from these studies should be applicable to all of the other 
areas in these two forests, since the underlying principles are identical 
and the climatic conditions very similar. 


WHITE-OAK SLASH. 


FUNGI WHICH ROT THE SLASH. 


Four main fungi were found rotting the white-oak slash, viz, 
Stereum rameale, S. versiforme, S. umbrinum, and S. fasciatum. All 
are sap-rotting fungi which cause but little apparent change in the 
texture of the wood. They produce what might be called indeter- 
minate rots, since there are no well-defined characteristics which 
mark any one of them. All slightly discolor the wood, which later 
becomes whitish in color, lighter in weight, and easily broken. 
Strange to say, each of these fungi rots its own special portion of 
the slash. Stereum rameale is usually found attacking twigs which 
_ bear the leaves and very small branches (1 inch or less in diameter). 
This fungus seems to begin on the twigs and works gradually down 
them to where the branches are about 1 inch in diameter; there two 
other fungi (S. versiforme and S. umbrinum) take up the work and 
rot the small branches up to 2 or 3 inches in diameter, where a fourth 
fungus (S. fasciatum) usually begins its attack on the wood. This 
is the main fungus which rots the sapwood of the logs and large 
branches 3 inches or more in diameter, and it is often found rotting 
the sapwood of the stumps as well as the boles and large branches 
of standing dead oak trees. None of these fungi destroys the 
attacked wood completely, its final disintegration being left to 
other groups of fungi, insects, etc. 

_ The heartwood of the large branches and trunks remains for many 
years after the sapwood is destroyed, but meantime it is being slowly 
rotted by a delignifying fungus (Sterewm frustulosum), which pro- 
luces small cavities or pockets in the wood. 

_ Other fungi of minor importance were found attacking the oak 
slash, the most important of which was a small, dark-brown, gelat- 


4 BULLETIN 496, U. S. DEPARTMENT OF AGRICULTURE. 


inous fungus (/'2dia glandulosa) found at irregular intervals along 
the twigs and small branches. Its action on the wood is to produce 
whitish rotten areas, usually extending entirely through the branch, 
thus forming a line of weakness which ultimately causes the branch 
to break into small sections (2 to several inches long). These pieces 
fall to the ground, where complete disintegration follows. 

Merulius corium, Hymenochaete curtisii, Diatrype stigma, and 
Stereum hirsutum are other fungi occasionally found attacking the 
twigs and small branches, while Merulius tremellosus, Polystictus 
pergamenus, P. versicolor, Polyporus gilvus, P. cinnabarinus, P. 
benzoinus, Lenzites betulina, Flammula sp., Panus stipticus, Stereum 
spadiceum, Lycoperdon pyriforme, Xylaria hypoxylon, and several 
species of Poria are occasionally found rotting logs, aig and 
large branches. 

Panus stipticus, Flammula sp., Merulius tremellosus, Xylaria 
hypoxylon, and Lycoperdon pyriforme are fungi which apparently 
attack wood which has been more or less rotted by other fungi. 

Polystictus pergamenus, P. versicolor, Polyporus gilvus, P. cinna- 
barinus, P. benzoinus, and Lenzites betulina rot both the sapwood 
and heartwood, but unfortunately none of them are common on oak 
slash in the forests of Arkansas. None of the fungi found rotting 
the oak slash produces a heart rot in the living tree. However, cer- 
tain fungi which cause heart rots in living oak trees will continue to 
grow in the infected wood after the trees are felled. The most impor- 
tant of these are Hydnum erinaceus, Polyporus pilotae, P. sulphu- 
reus, and Stereum subpileatum. 

BRUSH WHEN PULLED. 


Soon after a living tree is felled, wood-boring insects and various 
fungi begin their work of disintegration and decay. The first evi- 
dence of fungous activity in slash is a discoloration of the sapwood 
in the twigs, branches, and trunks, which usually begins a few 


months after the trees are felled. Marked evidences of decay in the ® 


shape of well-defined rotten spots and areas in the wood and the 
formation of fruiting bodies or sporophores of the wood-rotting 
fungi do not appear until one or two years after the trees are felled. 

All of the leaves in the tops of felled oak trees will usually fall in 
from one to three years, depending more or less upon the age of the 
leaves at the time the oak was cut and to a slight extent on the 
locality in which the timber is situated. 

The small branches and twigs gradually rot, and the majority of 
them will have fallen to the ground at the end of four years. By 


the end of six years practically all of the branches in the tops will § 


have rotted and fallen except some of the very large ones which 
have much heartwood. Also, practically all of the sapwood in the 
boles and cull logs will have rotted away during this time. 


» 
~ a 


INVESTIGATIONS OF THE ROTTING OF SLASH IN ARKANSAS. D 
BRUSH WHEN PILED. 


White-oak brush piles were examined, ranging from 1 to 5 years 
in age. During the first year after the trees were cut but little evi- 
dence of rot could be seen except a discoloration of the sapwood. By 
the end of the second or third year all of the leaves had fallen from 
the twigs which were exposed to the sun’s rays, and the brush at the 
tops and sides of the piles where exposed to the sunlight had rotted 
to some extent, while the slash in the middle of the piles not in actual 
contact with the ground and yet protected from the sunlight was 
rotted but slightly, if at all. The twigs and small branches at the 
bottoms of the piles were more or less rotted by certain other fungi 
(called “ ground” fungi in this bulletin), which apparently entered 
these branches from the soil. These ground fungi seem to rot the 
brush more rapidly and more thoroughly than the regular slash-, 
rotting fungi. 

Usually there is but little evidence of rot in the center of the piles 
during the first four years after piling. However, around the edges 
and through crevices in the top the sunlight sometimes penetrates 
sufficiently to permit slight fungous growth. Nevertheless, there is a 
marked difference between the rotting of the brush in the center of 
the piles not adjacent to the ground and that at the top and bottom 
of the pile. 

By the end of five years the top and bottom of the piles have rotted 
to a considerable extent, while the brush in the center of the piles, 
where it had become more or less exposed to the sun’s rays, was 
beginning to rot. 

For the brush in the center of the piles to rot completely it appar- 
ently (1) must be brought within range of the soil moisture by the 
rotting of the brush below it and by the settling of the pile, or (2) 
the upper portion must disintegrate sufficiently for the sun’s rays to 
reach the center of the pile. Undoubtedly, both conditions finally 
develop and aid in the rotting of the brush which was originally in 
the center of the piles. 

In a white-oak brush pile the layer of brush at the bottom would 
be the only one even in partial contact with the soil, while the 
remainder of the pile would be held from the soil by this first layer 
and therefore could not receive any benefit from the soil moisture. 
Neither are the piles dense or compact enough to raise the moisture 
content of the air around the brush in the piles sufficiently to encour- 
age the growth of the ground fungi in branches not in actual contact 
with the soil. On the other hand, the brush not in contact with the 
soil in the piles and yet sheltered from sunlight is deprived of the 
activity of the fungi which normally rot slash in the open; that is, 
slash when left as it falls in the tree tops. 


6 BULLETIN 496, U. S. DEPARTMENT OF AGRICULTURE. 


Since piles more than five years old were not found, the writer | | 


can not state positively the length of time necessary for a medium- 
sized compact brush pile of white oak to rot completely. Apparently 
it would take from three to six years longer than if the brush were 
either pulled or scattered. However, if the piles are very small, the 
brush will rot with about the same rapidity as when the tops are 
Jeft unlopped, since the sunlight can then penetrate to the bottom. 


SPOROPHORE DEVELOPMENT ON PILED BRUSH. 


The difference between the development of sporophores at the top, 
middle, and bottom of brush piles is very marked. Practically every 
twig and limb at the top of the pile bore the characteristic sporo- 
phores of Sterewm rameale, S. umbrinum, and S. versiforme on the 
rotting limbs, while no sporophores whatever were found on branches 
in the center of brush piles which were large and compact enough to 
exclude the sunlight. Very rarely were any sporophores of wood- 
rotting fungi ee on the material at the bottom of the piles, 
‘although sterile mycelium was frequently present on the brush so 
situated. It was therefore difficult to determine what fungi were con- 
cerned in the rotting of the brush in the bottom of the piles. How- 
ever, sporophores were found of Merulius tremellosus, Peniphora 
flavido- alba, Odontia sp., Poria pulchella, and two anlene eat 


species of Potie* 
BRUSH WHEN SCATTERED. 


When the brush is lopped and scattered it rots much more quickly 
than when piled, and in some localities somewhat more quickly than 
when left attached to the tops. On the areas examined the gain in 
the rotting of brush when scattered compared to that when pulled — 
was usually about one year. : 

When white-oak brush is scattered, only small portions of the limbs 
are actually in contact with the soil. The same fungi, therefore, that 
rot the unlopped brush will also rot most of the scattered brush, and 
with about the same rapidity. 

Brush lying on the ground sometimes absorbs from the soil suffi- 
cient moisture for the growth of ground fungi in those portions of 
the limbs which are in actual contact with the soil. On many of the 
areas examined the additional moisture obtained from the soil by the 
scattered brush was not sufficient to cause the ground fungi to attack 
the prostrate limbs. 

. The influence of soil moisture on the branches lying on the ground 
usually does not extend more than 4 to 6 inches from the point where 
the limb is in contact with the soil. This means that the benefit to be 
derived from the ground fungi rotting a branch is limited to that por- 
tion directly in contact with the soil. On account of the small quan- 


INVESTIGATIONS OF THE ROTTING OF SLASH IN ARKANSAS. 7 


tity of the brush thus situated, little of it is attacked by the ground 
fungi, and the benefits thereby derived are correspondingly slight. 

At the end of five to six years all of the brush (twigs and small 
branches) which was scattered will have rotted, and much of it will 
have disappeared. It was also no uncommon thing to find partially 
rotted brush, whether piled, scattered, or lopped, attacked by white 
ants (termites) and the partially rotted wood replaced to some extent 
by dirt. 


BLACK-OAK AND POST-OAK SLASH. 


Black-oak and post-oak slash was attacked by practically the same 
fungi which rot the white oak; however, but little of this type of 
slash was seen. The twigs and small-branches of the black oak in 
most of the cases examined seemed to rot somewhat more slowly 
than white-oak slash of the same character, while the post-oak slash 
seemed to rot with about the same rapidity as the white oak. 
Polyporus cinnabarinus was occasionally found rotting the large 
limbs and boles of the black oak, while the small twigs and limbs of 
_ the post-oak slash were sometimes attacked by Schizophyllum com- 
mune, and cull logs and stumps were occasionally attacked by 
 Lentinus lecomter. , Stereum ochraceo-flavum was the principal 
fungus found rotting fire-killed oak bushes 2 inches or less in diam- 
eter, while Polystictus pergamenus was the fungus usually found 
attacking fire-killed trees and fire-killed areas on standing living 
trees of all species of oak. 


SHORTLEAF-PINE SLASH. 


Shortleaf-pine slash was examined on areas which had been logged 
from two to nine years. 


FUNGI WHICH ROT THE SLASH. 


Two main fungi were found rotting the shortleaf-pine slash. One 
_ begins work in the ends of the small branches and works downward 
toward the trunk. This is usually Lenzites sepiaria, a dry-rot organ- 
ism prevalent throughout the United States. This fungus has never 
been found by the writer attacking slash which was not exposed to 
the direct rays of the sun. 

The second fungus enters the cull logs, boles of the tree tops, and 
branches 2 inches or more in diameter. It is what the writer pre- 
viously has called the “white-fir fungus” (Polystictus abietinus) 
It is a sap-rotting organism and usually rots but little, if any, of the 
heartwood. 


 ifiong, W. H. A new aspect of brush disposal in Arizona and New Mexico. In Proc. 
Soc. Amer. Foresters, v. 10, no. 4, p. 383-398. 1915. 


8 BULLETIN 496, U. S. DEPARTMENT OF AGRICULTURE. 


At the bottom of brush piles a fungus which has been identified as 
Polyporus amorphus was rather common. It apparently does not 
attack branches and limbs which are not in contact with the soil. 

Merulius ambiguus was occasionally found on small branches, 
while Yomes annosus, Poria subacida, and P. vaporaria were found 
on large prostrate limbs, trunks, and stumps. Polyporus palustris, 
Fomes annosus, and Corticium galactinum seem to be the principal 
fungi rotting the pine stumps. 


BRUSH WHEN PULLED. 


All of the needles in the tops of felled shortleaf-pine trees will 
fall in from one to three years, depending somewhat on the locality 
in which the timber is located. The branches will gradually rot, 
and many of them will have fallen from the trunk at the end of 
three to four years. By the end of five years practically all of the 
branches, large and small, in the tops will have rotted and fallen 
to the ground. Also, est of the i in the boles and cull logs 
will have rotted in this time. 

Pitchy limbs and trunks containing ie resin rot very slowly 
and may be found long after the less resinous wood has dis- 
appeared. 

Polystictus abietinus and Lenzites sepiaria seem to rot branches 
which are 8 to 10 feet from the ground just as rapidly as those near 
the ground. Lenzites sepiaria also attacks decorticated logs and the 
exposed portions of railroad ties after they are laid in the track. 


BRUSH WHEN PILED. 


Shortleaf-pine brush piles were examined, ranging from 1 to 5 
years in age. It was found that during the first year after the tree 
was cut but little rotting occurred, even in the small branches. By 
the end of the second or third year practically all of the needles had 
fallen from the limbs which were exposed to the sun’s rays, while the 
needles in the middle of the piles, which were protected by the 
overlying brush, were in good condition and still attached to the 
limbs. In five years, brush at the top of the piles had practically 
rotted as far as the fungi which were attacking them could rot it, 
while the brush in the middle of the piles showed few signs, if any, 
of rotting. In the bottom of the piles the brush was well rotted, but 
by fungi different from those rotting the brush at the top of the piles. 
In other words, a brush pile of shortleaf pine will be rotted at the 
top by Lenzites sepiaria and Polystictus abietinus, the center of the 
pile will be rotted but little, while the brush at the bottom of the pile 
in contact with the soil will be rotted by certain ground fungi, one 
of which has been identified as Polyporus amorphus. This means 
that before the center of the brush piles will rot, both the top and 


INVESTIGATIONS OF THE ROTTING OF SLASH IN ARKANSAS, 9 


bottom of the piles must disintegrate sufficiently to expose the center 
of the pile either to the sunlight or to the moisture of the soil. This 
would probably add from three to five years at least to the length of 
time it would take to rot the slash in the brush pile as compared to 
that required if pulled or scattered. 


BRUSH WHEN SCATTERED. 


Practically the same conditions hold for shortleaf-pine slash when 
lopped and scattered as for oak slash; that is, the same groups of 
fungi which attack the pulled pine slash will attack the slash when 
scattered on the ground unless it be covered with leaf débris. Ground 
fungi will also attack that portion of the brush immediately in con- 
tact with the soil, provided the area under consideration is not too 
dry, like the south and southeast slopes of steep hillsides. In such 
locations no evidence was found of ground fungi attacking the scat- 
tered brush, or even the brush in the bottom of the piles. This means 
that the pine brush when lopped and scattered will rot much quicker 
than when it is piled, and on some sites shghtly quicker than when 
left attached to the tops or pulled. 


THE GROWTH OF WOOD-ROTTING FUNGI. 


There is this physical factor to be kept in mind when considering 
the rotting of slash, viz, that the quantity of water which a limb or 
branch obtains is practically limited to the precipitation which that 
limb or branch receives and is able to absorb through its bark into the 
sapwood and that, so far as the amount of moisture in the wood itself 
is concerned, the humidity of the air around the branch would not 
be an important factor, since conditions would have to be very unique 
which would enable a branch covered with bark to absorb from the 
surrounding air a sufficient quantity of water to make any appreci- 
able difference in the water content of the branch or limb. This 
would mean that the distance the branch was from the ground, 
whether 1 foot or 5 feet, would make but little difference in the rela- 
tive supply of moisture obtainable from the atmosphere which the 
wood-rotting fungi in the branch could utilize. It might, however, 
determine to a slight extent the amount of moisture which the limbs 
could lose, especially in the bottoms of the piles. In regions of heavy 
dews the brush lying within 1 or 2 feet of the ground might obtain 
more moisture than brush farther from the ground. 

This indicates that the slash would have to be practically in con- 
tact with the soil to gain any appreciable quantity of moisture other 
than that obtained from precipitation, and from the very nature of 
the oak brush only small portions of any given limb would be thus 
placed. 


10 BULLETIN 496, U. S. DEPARTMENT OF AGRICULTURE. 


Different groups of fungi seem to have adapted themselves to 
certain growth conditions. For instance, Stereum rameale and S. 
hirsutum were usually found only on the twigs and small branches, 
while S. wnbrinum and S. versiforme occurred mainly on twigs and 
branches 2 inches or less in diameter. None of these four fungi were 
found attacking large limbs and trunks of the felled trees, while S. 
fasciatum, very common on stumps and trunks, rarely occurred on 
branches less than 3 inches in diameter. None of them were found 
growing on timber which was entirely shaded from the sun. 

The fungi which rot that portion of the branches lying in actual 
contact with the ground under the brush piles belong to an entirely 
different group. Such fungi apparently need a large supply of 
moisture and probably enter the wood from mycelia already growing 
and ramifying in the leaf débris in the soil. This group of fungi 
includes those which are normally found attacking wood partially 
or entirely buried in the soil, such as stumps and posts. 


WHY BRUSH IN THE CENTER OF THE PILE DOES NOT ROT. 


Why the fungi which are found attacking the limbs exposed to 
the sunlight will not usually attack the brush in the center or bottom 
of the piles when protected from the sun’s rays is not known. Ap- 
parently temperature and moisture are not the only prominent fac- 
tors controlling fungous growth and activity in nature. Is it pos- 
sible that sunlight is a factor in the germination and growth of 
wood-rotting fungi in their natural habitats? 

In a previous article by the writer,’ the theory was advanced that 
the reason why the brush in the center and bottoms of the piles in 
the semiarid regions of Arizona and New Mexico did not rot was 
due to temperature conditions prevailing in the high altitudes. That 
the temperature in Arkansas could be a prominent factor in the 
rotting of the brush, or, rather, in the lack of the rotting of the brush 
in the middle of the piles, seems hardly possible, since the tempera- 
ture there is sufficiently high during a large portion of the year for 
fungous mycelia to grow vigorously, provided the other factors 
necessary for fungous growth are also present. 

The precipitation in Arkansas is sufficient to supply all the mois- 
ture necessary throughout the entire brush pile for the active growth 
of wood-rotting fungi. It seems, therefore, that enough moisture 
would persist in the center of the piles for the brush to rot at least 
as rapidly as the pulled brush. The fact that twigs and branches in 
the center of piles large enough to be shaded from the rays of the 


sun were the only ones not rotted seems to indicate that sunlight may 4 


possibly play a part in the rotting of the brush, not only in Arkansas, 


1Long, W. H. Op. cit., p. 395-396. 


INVESTIGATIONS OF THE ROTTING OF SLASH IN ARKANSAS. 11 


but also in Arizona and New Mexico, where the same conditions as 
to the rotting of the limbs in the center of the piles were found to 


exist. 


It is very evident that certain groups of fungi capable of rotting 
the small twigs and branches of trees which have died in the forest 
or of trees which have been felled are not capable of thriving under 
the conditions found in the center of large and compact brush piles. 
This is further accentuated by the fact that the bottoms of the brush 
piles in Arkansas, when rotted at all, are not rotted by these fungi, 
but are attacked by other fungi, such as Yomes annosus, which are 
known to live in more or less shaded and underground habitats. 

What the factors are that dominate the growth and activity of 
these various groups of fungi is not known. For instance, why 
is it that usually Sterewm rameale and S. hirsutum rarely attack 
limbs above 1 inch in diameter, while S. wmbrinum and S. versi- 
forme are rarely found in limbs larger than 2 or 3 inches in diameter ? 
Why do not these fungi usually attack logs and large branches? Is 
the moisture content too high or the temperature too low? On the 
other hand, Sterewm fasciatum, the common fungus rotting the cull 
logs and boles of the oak slash, usually does not attack the twigs and 
small branches. Of course, the explanation for this fungus might 
be that the twigs and small branches have not a sufficient amount of 
moisture, but such an explanation could not be offered for the failure 
of Stereum rameale, S. versiforme, and S. umbrinum to attack the 
large branches and trunks. 

It would seem that but little is known concerning the real factors 
controlling fungous activity in wood. It is evident, however, that 
certain groups of fungi are capable of rotting the wood as it is nor- 
mally found in nature; that is, when a tree dies, is killed by light- 
ning, or is wind thrown. These are conditions which have been oc- 
curring in nature through centuries, and certain fungi have adapted 
themselves to such conditions. The same could be said of limbs and 
logs which are in contact with the soil, or even buried in the soil, 
since such conditions are normal and found generally in nature. 
Apparently there are no fungi capable of vigorous growth under 
the artificial environments found in the center of large brush piles, 
_ where the conditions do not approximate those existing either when - 
the brush is in contact with the soil or when it is exposed to the 
— sunlight. 

GENERAL DISCUSSION. 


Several factors, such as fire, reproduction, and the rotting of the 
_ brush, are so intimately associated that it is impossible to discuss 
_any one phase of brush disposal without noting, at least briefly, the 


ee 


1Long, W. H. Op. cit., p. 889-390. 


12 BULLETIN 496, U. S. DEPARTMENT OF AGRICULTURE. 


possible influence of these other factors. It is obviously impossible 
to arrive at any legitimate conclusion concerning the best method 
of brush disposal by limiting the discussion to the pathological side 
of the question as seen in the rotting of the brush itself. The fire 
hazard, as it seems to exist in Arkansas, is therefore briefly discussed 
in connection with brush disposal from the pathological viewpoint. 

In the Arkansas National Forest about 3 to 5 white-oak trees are 
felled to the acre, and about 5 to 10 pine trees to the acre. In the 
Ozark National Forest the proportion of white-oak trees felled is 
somewhat greater, running probably from 5 to 10 trees to the acre, 
while there is but very little pine cut on this forest. This means 
that on any area in either of these two National Forests where timber 
is being cut, especially white oak, a much greater percentage of 
standing trees of all sizes, including those below the merchantable 
diameter limit, is left than is cut. This standing timber will add its 
annual quota of fallen leaves to the ground cover, irrespective of 
what method of brush disposal is followed. The amount of litter in 
the shape of slash, on account of the small number of trees cut per 
acre, in many cases will not make fires more likely to start or prevent 
their control, since there will always be a sufficient quantity of leaf 
litter and underbrush present to make a good ground fire, even if 
there be no slash on the ground. If the deciduous trees are cut with 
the leaves on them the amount of leaf litter will not be increased, 
since these leaves would fall to the ground in the autumn even if the 
trees were not cut; in fact, there would really be less leaf litter on 
the ground, because the leaves persist on the felled tree tops and 
branches from one to three years. 

There is also this fact to be borne in mind, that oak trees cut from 
November to March, inclusive, are leafless or practically so, and the 
brush from them will net materially increase the fire hazard unless 
it is piled. 

In 1912 and 1913 the writer visited areas in the Ozark National 
Forest which were then being logged. In the studies made in 1915, 
only two to three years later, many of these areas had been burned 
over. It can probably be said truthfully that the greater portion of 
the Ozark National Forest, except about 100,000 acres in the middle 
of the central division, will be burned over at least once within a 
period of five years, and often within a much shorter interval. It 
seems, therefore, that whatever system of brush disposal is followed 
in this forest should take into consideration the certainty of fire as 
well as the rotting of the brush. 

In the Arkansas National Forest many areas are not burned over 
more than once in every 20 years. Under such conditions the rot- 
ting of the brush is the main factor to be considered. 


et omc Ge eee s/h 


ae 


ee - — 
ee ee een ee 8 OS 


INVESTIGATIONS OF THE ROTTING OF SLASH IN ARKANSAS. 13 


No areas were seen on which brush had been cut and scattered 
where there had been fire. What effect, therefore, a fire would have 
on such areas as compared with those on which brush had been piled 
or pulled can not be stated from actual observation. However, areas 
were seen on which there had been fires where brush had either been 
pulled or piled. Many trees whose tops had been left with the limbs 
unlopped were seen with the needles or leaves burned from only 
the lower half of the tops. This leaving unburned the leaves and 
needles in the upper half of the felled tree tops seemed to indicate 
that fires in the forests of Arkansas in pulled brush do but little, 
if any, more damage than the regular ground fire which is fed by the 
normal annual leaf débris and underbrush. Many areas on which the 
brush had been piled were seen where forest fires had killed a large 
portion of the young reproduction up to 4 inches in diameter. 

Brush when lopped and piled rots much more slowly than under 
either of the other methods of disposal. Such piles may be expected 
to persist from three to six years longer than the same brush when 
pulled or scattered, depending upon the size and compactness of the 
piles. This would eliminate the large brush piles from consideration 
in disposing of the slash on these areas. 

The best method of brush disposal over such areas would be that 
which is the least expensive, which reduces to a minimum the damage 
to the forest when fires occur, and which leaves the slash in such 
condition that it will rot most rapidly. It is very evident in view of 
these three things that the lopping and piling of the brush is the 
poorest method to follow, since not only is it the most expensive, but 
brush when piled rots the slowest and the reproduction on such areas 
is apparently damaged most by forest fires, judging from the burned 
areas seen. This would leave the choice between scattering and 
pulling. 

Pulling, as practiced in coniferous timber, would not be practicable 
in certain types of hardwood sales, such as stave sales, since the oak 
tops are usually too heavy to be moved as a whole by the methods of 
logging in use on such areas. However, when tree tops fall near 
reproduction or near trees to be left, it is immaterial whether the 
top is pulled away by a team or by hand or whether the objectionable 
sections of the top are sawed out and rolled away. 

Brush when pulled or left in the tops rots with nearly the same 
rapidity as when lopped and scattered. The difference in time be- 
tween the rotting of the pulled and of the scattered brush is appar- 
ently about one year in favor of the scattered brush. Whether a 
possible maximum gain of one year in the time of rotting between 
the brush that is pulled and that which is scattered is sufficient to 
offset the difference in cost between these two methods must, of 
course, be considered. 


14 BULLETIN 496, U. S. DEPARTMENT OF AGRICULTURE. 
SUMMARY. 


(1) When the brush is lopped and scattered it rots more rapidly 
than when either piled or pulled. This is due to the fact that two 
types of fungi rot the brush, one entering the limbs and branches 
not in direct contact with the ground and the other entering those 
portions of the brush in actual contact with the soil. 

(2) The maximum gain in the rapidity of the rotting of the brush 
when scattered over the same brush when left unlopped in the tree 
tops is about one year. On dry areas, such as steep hillsides with 
southern and western exposures, there is practically no difference in 
the rate of rotting of the brush when scattered and when the tree 
tops are left unlopped. 

(3) Brush when lopped and piled will apparently take from three 
to six years longer to rot than when scattered or when left unlopped. 

(4) Brush when piled is rotted at the top by one group of fungi 
and at the bottom by another group, while the middle of the pile, not 
in contact with the soil and yet protected from the sunlight, ap- 
parently will not rot to any extent until the pile disintegrates sufii- 
ciently to expose these central layers to the soil moisture on the one 
hand or to the sunlight on the other. 

(5) The same general facts as to the rotting of the slash hold for 
all species of timber (pine, oak, etc.) examined in Arkansas. 

(6) Four fungi are the main agents in the rotting of oak slash in 
Arkansas, viz, Stereum rameale, S. wmbrinum, S. versiforine, and 
S. fasciatum. 

(7) Two main fungi rot the shortleaf-pine slash, viz, Polystictus 
abietinus and Lenzites sepiaria. 

(8) No definite conclusions could be reached concerning the prin- 
cipal fungi which rot the bottom of the piles, since but few sporo- 
phores of such fungi were found. 

(9) None of the main fungi concerned in rotting either the oak 
or the pine slash in Arkansas produce heart rots in living trees. 


PUBLICATIONS OF THE U. S. DEPARTMENT OF AGRICULTURE 
RELATING TO DISEASES OF TREES. 


AVAILABLE FOR FREE DISTRIBUTION BY THE DEPARTMENT. 


The Death of Chestnuts and Oaks Due to Armillaria mellea. (Department Bul- 
letin 89.) 

The Life History of Lodgepole Pine in the Rocky Mountains. (Department 
Bulletin 154.) Asc) 

Life History of Shortleaf Pine. (Department Bulletin 244.) 

A Disease of Pines Caused by Cronartium pyriforme. (Department Bulletin 
247.) 

The Care and Improvement of the Woodlot. (Farmers’ Bulletin 711.) 

The Preservative Treatment of Farm Timbers. (Farmers’ Bulletin 744.) 

Fire-Killed Douglas Fir: A Study of Its Rate of Deterioration, Usability, and 

, Strength. (Forestry Bulletin 112.) 
Practical Tree Surgery. (Separate 622 from Yearbook, 1913.) 

Forest Tree Diseases Common in California and Nevada. (Forest Service, Mis- 
cellaneous Publications. ) 


FOR SALE BY THE SUPERINTENDENT OF DOCUMENTS, GOVERNMENT PRINTING 
OFFICE, WASHINGTON, D. C. 


The Control of the Chestnut Bark Disease. (Farmers’ Bulletin 467.) Price, 
5 cents. 

Sap-Rot and Other Diseases of the Red Gum. (Bureau of Plant Industry Bul- 
letin 114.) Price, 15 cents. 

The Mistletoe Pest in the Southwest. (Bureau of Plant Industry Bulletin 166.) 
Price, 10 cents. 

The Timber Rot Caused by Lenzites sepiaria. (Bureau of Plant Industry Bul- 
letin 214.) Price, 10 cents. 

Forest Pathology in Forest Regulation. (Department Bulletin 275.) Price, 
10 cents. 

15 


ADDITIONAL COPIES 
OF THIS PUBLICATION MAY BE PROCURED FROM 
THE SUPERINTENDENT OF DOCUMENTS 
GOVERNMENT PRINTING OFFICE 
WASHINGTON, D. C. 
AT 


6 CENTS PER COPY 
V e 


> 
2: 3 x 
f F 
a a eg a) ” eet 
. ves Se ie ies 
¥ s 
‘ ' 
< 
4 a 
7 bd ; ‘ ‘J 
or ee tS aay tnx Seta pied 
ie? Ue kp oe j Re c? foe LF t 
ke Ok be a 
aie | ie pe z! 
— 
A ’ 10 
, E 
' 
.¢ 4 + 
F ; 
| ; ‘ i= f 
“ay i 
. < 
} 
} ’ i= 
. ” 5 
| 
| » 
; 
; ’ 
| 
; 
‘ 
Ss 
wey FP 
iy 
“~~ FF 
. > 
: ; 
Py : he 
: oral te 
P 
a to" 
Hoke AAAS: 
bsg ya sane 
Mga th Te. ‘i ; ; ; 
: + ae Se 
= ‘ te fy Digegeae Oa Y ae ot Oe 
; SRP (Mate y itet? 3 
{ “pan 
. ge 
.f af I 


ee a Sh er ne 


UNITED STATES DEPARTMENT OF AGRICULTURE 


, BULLETIN No. 510 


Contribution from the Bureau of Plant Industry 
WM. A. TAYLOR, Chief 


Washington, D. C. PROFESSIONAL PAPER May 17, 1917 


TIMBER STORAGE CONDITIONS IN THE EASTERN AND 
SOUTHERN STATES WITH REFERENCE TO DECAY 
PROBLEMS. 


By C. J. HUMPHREY, reer eat Office of Investigations in Forest Pathology. 


(In cooperation aoe the Forest Products Laboratory of the United States Forest Service, 
Madison, Wis.) 


CONTENTS. 
Page Page 
PON EAGT ee ee) toe tice acininihene4 a einewe ~2e 1 | Condition of storage yards at mills........... 11 
HUatispiOndecay Il GINIDED... 5... -22.---c----- _ 2 | Handling timber at retail yards.............. 27 
Handling timber at sawmills....... EGE Eb e 7 | Fungi which rot stored lumber.............. 30 
Location of mills and its relation to decay... 8 | Wood preservatives in the lumberyard....... 38 
Quality of stock with reference to decay...... 9. || Branding structural timber... 2.2 -<-.5...5..- 40 
Condition of storage sheds at mills........... 10'\)\ AGC NSIGMS Ii a. S02 oe eee t dees boone 41 
INTRODUCTION. 


During the past few years a large number of requests for infor- 
mation on the control of decay in building and factory timbers have 
reached the United States Department of Agriculture. In many 
instances the cases reported have involved serious losses, often run- 
ning into the thousands of dollars. 

The rapidly rising interest in the question on the part of the public 
may be attributed to two general causes: (1) The greater publicity 
being given to this work in the Department of Agriculture, partic- 
ularly through the activities of the Office of Investigations in Forest 
Pathology of the Bureau of Plant Industry and the Forest Products 
Laboratory of the Forest Service, and (2) the increasing use of 


_ timber less resistant to decay, which has become very marked during 


the past decade. 
As a preliminary to an investigation into the prevalence of decay 
in building timbers, with the prime object of securing some basis for 
71022°—17———1 


2 BULLETIN 510, U. S. DEPARTMENT OF AGRICULTURE, 


the effective control of such losses, a field study covering about seven | 
months’ active work was undertaken during 1914 to determine the 
conditions under which lumber and structural timbers are stored, 
for it is a well-known fact that timber infected with wood-destroying 
fungi during storage may be the direct cause of outbreaks of rot in 
buildings when such timber is placed in situations favorable to decay. 

On account of the many failures in timber in important structures 
during recent years, sich an investigation is of the highest impor- 
tance, both from the standpoint of owners and contractors and from 
that of the timber interests themselves. 

The writer has encountered a number of instances where he was 
informed that wood has been replaced by steel or concrete for no 
other reason than the failure of locally available timber to withstand 
decay. An increasing use of these structural materials is bound to 
occur unless the lumber industry takes steps to improve the quality 
of its product for the North American market, and the first step in 
this process of regeneration les in the better sanitation of lumber 
storage yards, so as to remove the danger of directly transferring 
fungous infections from the lumber dealer to the consumer. 

During the course of this study a large number of sawmills and 
wholesale and retail lumberyards were visited in the eastern half 
of the United States. The region comprised 10 States along the 
Atlantic coast from Maine to Florida, all of the Gulf States, and 
the Central States of Arkansas, Iowa, Illinois, and Wisconsin. In 
addition to a personal inspection of the yards, much valuable in- 
formation was obtained directly from the operators. 


CAUSE OF DECAY IN TIMBER. 


Decay in timber is almost exclusively due to the action of fungi, 
the greater part of the destruction being referable to one of the 
higher groups of these organisms, namely, the Hymenomycetes. In 
the life cycle of these fungi there are two distinct phases of develop- 
ment: (1) The vegetative stage (mycelium) and (2) the fruiting 
stage. 

MYCELIUM. 


The mycelium consists of microscopic threadlike filaments, usually 
branched, which penetrate the wood either by traversing the natural 
longitudinal passages, such as the pores, resin canals, or cell cavities, 
or by passing through the walls or through the pits in the walls of 
the wood fibers or tracheids (PI. I, fig. 1). The mycelium also in- 
vades the pith rays, which contain a great abundance of food mate- 

1JIn this connection, see the report by F. J. Hoxie, entitled ‘‘ Dry Rot in Factory Tim- 


bers,” 34 p., 19 fig., Boston, 1915, published by the Inspection Department of the Asso- 
ciated Factory Mutual Fire Insurance Companies, Boston, Mass. 


ES 


——————————— 


a 


TIMBER STORAGE IN THE EASTERN AND SOUTHERN STATES. 3 


rials readily available to the fungus and whose walls are thinner 
than those of the wood fibers and hence more readily penetrated. 
The growth of the mycelium is conditioned by four factors: 
(1) The presence of satisfactory food supplies, (2) a suitable amount 
of moisture in the wood, (3) a temperature favorable for growth, 
and (4) at least a small supply of air to furnish the necessary oxygen. 
Food supplies—The mycelium, being a living, growing plant, 
must have nourishment for growth, and so utilizes for this purpose 
various constituents of the wood substance. These consist of the 
different compounds which go to make up wood tissue, the celluloses 
and ligno-celluloses being utilized as well as sugars, starches, and 
certain organic acids. To break down the woody tissues, which are 
chemically very complex, and thus render them assimilable to the 
fungus, certain imperfectly understood chemical substances (en- 
zyms or ferments) are secreted by the organism. These act upon 
the wood substance, reducing it to simpler nutritive compounds. A 
number of these ferments have been isolated and studied by various 
investigators and their physiological and chemical action deter- 
mined. They are quite specific in their action; different substances 
which enter into the composition of wood require different ferments 
to disorganize them. In general, however, the wood-destroying 
fungi are well supplied with the ferments necessary to produce ‘seri- 


ous disintegration of most of the constituents of woody tissues. 


Moisture-—A considerable amount of moisture is necessary for — 
rapid decay. Timber in an air-dry condition during dry weather 
will not ordinarily be affected, but during periods of rainy weather, 
when the atmospheric humidity is high, fungous infections may 
become serious. In highly humid stagnant air a surface development 
of mycelium (PI. I, fig. 2) is possible, but under conditions of free 
air circulation the surface is usually kept too dry for this to occur, 
although the interior of large timbers may still retain sufficient 


moisture for decay to progress within them. 


Temperature.—W ood-destroying fungi can maintain themselves 
over rather wide ranges of temperature, but have an optimum. for 
most rapid development within comparatively narrow limits. Ac- 
cording to German investigations Merulius lachrymans (Wulf.) Fr. 
has an optimum between 65° and 72° F. (18° and 22° C.); Conio- 
phora cerebella (Pers.) Schrét. (=C. puteana (Schum.) Fr.) be- 
tween 72° and 79° F. (22° and 26° C.), and Lenzites sepiaria (Wulf.) 
Fr. between 82° and 90° F. (28° and 32° C.). 

Growth below these points is often considerably retarded, while 
a rise of 4 to 8 degrees above the optimum often causes total inhibi- 
tion of growth or even death, as in the case of Merulius lachrymans, 


_ which is very sensitive to temperature changes above the optimum. 


4 BULLETIN 510, U. S. DEPARTMENT OF AGRICULTURE, 


Air.—Under ordinary conditions the air supply within and sur- 
rounding the timber is amply sufficient for decay. Fungi develop 
best in still air in closed spaces, but this is due to the greater humidity — 
rather than to air requirements, for a good air circulation dries the _ 
timber to a point unfavorable to the development of the organisms, 

In the case of timber thoroughly saturated with water, however, 
so that the cell cavities are filled with the liquid, decaxa is prevented 
entirely through lack of sufficient oxygen. 


FRUITING BODIES. 


Fruiting bodies are an expression of fungous activity within the 
wood. They form only after decay has well started. They appear at 
the surface in the form of single or imbricate shelves or brackets, 
leathery or waxy incrustations, or, in a few cases, as mushrooms ~ 
(PL. I, fig. 3) with central or eccentric stems bearing an expanded 
cap at the top. 4 

The fruit bodies of the many fungi which cause decay i in timber 
may vary in color from white through reds and yellows to dark © 
brown or blackish. The consistency or texture is also highly vari- — 
able, from fleshy to tough and leathery, and occasionally hard and — 


woody. In some species the under side, or outer surface where the ~ 


fungus is spread out as a crust (resupinate), is smooth (Stereum, — 
Corticium, Peniophora, Coniophora (frequently warted)). In other — 
cases, the under side, or the outer surface where resupinate, bears 
numerous pores (Polyporus, Poria (Pl. I, fig. 5), Merulius, Tra- 


metes, Daedalea, Fomes). Still other species have platelike gills on — 


the under side (Schizophyllum, Lentinus, Lenzites). Occasionally, 


forms with distinct spines (PI. I, fig. 4) or teeth are encountered — 


(Hydnum). Various other species are illustrated in Plates III © 
to X. 


HOW WOOD-DESTROYING FUNGI SPREAD. 


There are two general methods by which wood-destroying fungi — 
spread from infected to sound timber: (1) By a direct overgrowth of — 
mycelium from an infected stick to adjoining or near-by timber, and — 
(2) by the blowing about of spores produced by the fruit bodies or — 
by the mycelium. | § 

Infections by mycelium—tIn wholly or partially inclosed moist — 
spaces, such as are often found in the basements of buildings, in 
mines, or beneath low, poorly ventilated lumber piles, the mycelium ~ 
finds sufficient moisture in the air to allow it to develop on the © 
surface of timbers, and in this way may progress along the timber — 
for considerable distances. Such may be the case also where timber — 
is close piled; the writer has records where severe infections have ~ 


| 


TIMBER STORAGE IN THE EASTERN AND SOUTHERN STATES. 5 


thus passed during rainy weather from the bottom upward through 
piles 12 to 15 feet high. In lumber storage sheds or in the base 
of close piles the mycelium of several species of fungi has frequently 
been observed developing in great abundance, not alone on the moist 
foundations and lower layers of lumber (PI. II, fig. 1), but also 
spreading profusely on the soil (PI. II, figs. 2 and 3). 

With some species of wood-destroying fungi the mycelium within 
infected timber may remain alive for long periods, even under air- 
dry conditions, a fact which makes the use of infected timber in 
building operations a dangerous procedure. As an example, we have 
the experimental evidence advanced by Bayliss: that the mycelium 
of Polystictus versicolor in wood can survive a period of four years 
under the dry conditions of a herbarium. 

Infections by spores——The chief purpose of spore formation in 


_ fungi, just as in seed formation in ordinary green plants, is the 


bok 6 I ue be tA i aie Lae A 


perpetuation of the species through reproduction. Spores serve 
the two-fold purpose of tiding the fungus over unfavorable periods 
and of allowing its rapid spread under favorable growth conditions. 
Nature is lavish in her methods, and the number of spores produced 
is often enormous. For instance, Buller? computed from partial 
counts that each pore on the under side of Polyporus squamosus 


_ produced in the course of a few hours an average of 1,700,000 spores, 
or a total of over eleven billion for the entire under surface of a 


fruit body having an area of 250 square centimeters (38.75 sq. in.). 


_ When one recalls that spores are either constantly or intermittently 


produced by a single fruit body over a long period the further state- 
ment made by Buller that “the number of spores produced by a 
single fungus * * * in the course of a year may, therefore, 
be some fifty times the population of the globe ” becomes intelligible. 

At least two general types of spores are recognized for most wood- 
destroying fungi, the most easily observed being the basidiospores 
produced by the fruit bodies. These may frequently be seen en 
masse as a white or colored powdery deposit which has fallen from 
the sporophores (Pl. II, fig. 4). These spores are produced on 
short stalks at the ends of club-shaped cells which form a palisade 
layer (Pl. II, fig. 6) covering the under surface of the fruit body, 
or, in case the fruit body is of the incrusting type, covering its outer 


surface. When mature, the spores are cast off the basidia into the 


air and are blown about by the wind. When they lodge in.a moist 


place, favorable for growth they readily germinate and produce a 
new infection. 


1 Bayliss, Jessie S. The biology of Polystictus versicolor (Fries). In Jour. Econ. 
Biol., v. 3, no. 1, p. 1-24, 2 pl. 1908. 

£Buller, A. H. R. The biology of Polyporus squamosus Huds., a timber-destroying 
fungus. Jn Jour. Econ. Biol., v. 1, no. 3, p. 101-138, illus., pl. 5-19. 1906. 


6 BULLETIN 510, U. S. DEPARTMENT OF AGRICULTURE. 


Both the fruit bodies and basidiospores vary greatly in vitality 
among the different species of fungi. - External temperature and 
moisture conditions exert a great influence, particularly when the 
two are working together in an unfavorable réle. 

Low temperatures appear far less injurious than high temperatures, 
Buller and Cameron? report gathering living fruit bodies of Schizo- 


phyllum commune from a woodpile at Winnipeg,.Canada, in March 


at a temperature of —17° C. (1° F.), after exposure for several 
months at winter temperatures ranging between —15° and —40° C. 
(5° and —40° F.). After thawing for a few hours the fruit bodies 
cast spores readily. They further report that immersing an active 
fruit body of the same fungus in water and placing it in the open 
over night at a minimum temperature of —31° C. (—24° F.) did not 


suffice to kill the organism, although it was frozen into a solid block — 


of ice. 

Carrying the work still farther, Buller? exposed fruit bodies of 
the same fungus (previously kept dry for two years and eight months 
in ordinary air) to the temperature of liquid air, —1902 C. (—310° 
F.), for three weeks in a vacuum tube. Upon removal and moisten- 
ing, the fruit bodies were still alive and cast spores in abundance. 

In his larger work* and certain later articles, the same author 
shows that at ordinary temperatures dried fruit bodies retain their 
capacity to produce spores for long periods; for instance, Daedalea 
unicolor can remain alive in the dark at least 84+ years and Schizo- 
phyllum commune at least 64 years. Certain others may retain their 
vitality. for only two or three years. 


In the case of temperatures above the optimum, however, the in- 


jurious effect may become marked within a comparatively small 


range. For instance, Falck* states that fruit bodies of Lenzttes } 
abietina fail to produce spores after five days at 26° (78° F.) and ~ 
the spores fail to germinate at 42° C. (108° F.). A corresponding — 


relation is also said to exist with Merulius lachrymans and other 
species, for the same author ® states that fresh fruit bodies of Meru- 


lius domesticus (=M. lachrymans in part) are killed in 30 minutes . 
at 40° to 42° (104° to 108° F.) and in 15 minutes at 46° C. (115° » 


F.) ; at 42° C. (108° F.) dry spores are killed in 12 to 16 hours. 


In addition to spores produced in fruit bodies, another set of $ 


reproductive bodies is often produced directly by the mycelium. 


1 Buller, A. H. R., and Cameron, A. T. On the temporary suspension of vitality in ~ 


the fruit bodies of certain Hymenomycetes. In Proc. and Trans. Roy. Soc. Canada, s. 3, 
v. 6, 1912, sec. 4, p. 78-78. 1913. 


2Buller, A. H. R. Upon the retention.of vitality by dried fruit bodies of certain 4 


Hymenomycetes, including an account of an experiment with liquid air. In Brit. Mycol. 
Soc. Trans., v. 4, 1912, pt. 1, p. 106-112. 1913. 
3 Buller, A. H. R. Researches on Fungi . . . 287 p., illus., 5 fold. pl. London, 1909. 


4HWalek, Richard. Die Lenzites-Fiule des Coniferenholzes. In Moller, Alfred. Haus- — E 


- sechwammforschungen. Heft 3, p. 69 and 98. 1909. 


5 Falck, Richard. Die Merulius-Fiiule des Bauholzes. Jn Moller, Alfred. Haus- — 


schwammforschungen. Heft 6, p. 339. 1912. 


~ —————— ee 7 _ 


TIMBER STORAGE IN THE EASTERN AND SOUTHERN STATES. 7 


These bodies may be borne on short stalks on the mycelial threads 
(conidia), or the mycelium itself may break up into short cells 
(oidia), or specialized thick-walled cells (chlamydospores) may form 
within the mycelium. The last kind of spore, on account of its 
thicker wall, is adapted to withstand unfavorable weather conditions; 
the two former kinds are usually thin walled, minute, and readily 
blown about by the wind. 

With these fundamental facts in mind, let: us now turn to a discus- 
sion of the present conditions under which timber is stored and see 
wherein these conditions contravene the known facts regarding the 
development and 
spread of decay-pro- 
ducing fungi. 


HANDLING TIMBER 
AT SAWMILLS. 


The practice at 
different sawmills va- 
ries widely. A few 
of the larger mills, 
particularly in the 
longleaf-pine belt, put 
almost their entire 
cut through the dry 
kiln and then store it 
under closed sheds. 
This practice is to be 
highly commended, 
and if the storage 
sheds are well 
drained and properly 


ventilated beneath, no peor 
- Fig. 1.—Bird’s-eye view of a clean lumber-mill yard in 
trouble from fungi : ‘ 


: Arkansas, showing the usual method of open storage. 
should be experienced. 


However, comparatively few mills have the facilities for handling 
their product in this approved fashion, and the great majority have 
kiln capacity for only the B and better grades of lumber. The re- 
mainder of the output is piled in the open yard (fig. 1), the higher 


grades of lumber often being dipped in sodium bicarbonate or sodium 


carbonate to prevent blue stain. 

Some few mills of the poorer class and smaller type dispense with 
both kiln drying and dipping and pile their entire green stock in the 
open yard. The few mills of this type which the writer has visited 
are usually also very lax in their methods of piling and of yard 
sanitation. 


8 BULLETIN 510, U. S. DEPARTMENT OF AGRICULTURE. 


—_——— ee 


LOCATION OF MILLS AND ITS RELATION TO DECAY. 


The location of sawmills is usually determined by certain economic 
considerations which do not readily admit of change. Many of the 


P64F 
His: 2.—Lumber piled at the water’s edge on the Atlantic Abe High waves sweep over 


this during storms, wetting the lumber and pr oducing rot. ‘ 


mills are located either on streams or along the low and swampy 
Atlantic or Gulf coasts. Very often Pieper dry land is not available 
for storage purposes 
and then, particu- 
larly in the South, — 
the conditions for — 
decay are excellent. 
In some instances at- 
tempts have been ~— 
made to fill in this ~ 
low land with saw- 
dust, bark débris, — 
etc., with the result — 
that the soil is made 
over into a most ex- 
cellent culture me- 


P65F 


Fig. 3.—Silt deposited in the base of a lumber stack during dium for the devel- 


a Mississippi River flood. This condition permits the 


lumber to rot rapidly. opment of wood- 


destroying fungi. In 

other cases yards, even when on comparatively high ground, are so 

graded as to allow drainage into the yard rather than away from it. 

In the coastal regions, where mills are at times located just above 
the level of high tide, storm waves frequently beat in from the sea 


Bul. 510, U. S. Dept. of Agriculture. PLATE I. 


OO ..auitinan Pat 
ms er 


Pe 


LUMBER SANITATION: WOOD-ROTTING FUNGI.—I. 


Fig. 1.—Thin section of ‘‘red-heart’”’ pine, showing fungous threads and holes where these have bored 
through the walls of the wood cells. Fia. 2.—Mycelium on a board from a clay mine, Joplin, Mo. 
Fic. 3.—The mushroom Pluteus cervinus on a rotten log. Fic. 4.—A species of Hydnum., 


Bul. 510, U. S. Dept. of Agriculture. PLATE II. 


: sisal nk 
te. Sot 
eee & 


LUMBER SANITATION: WooD-ROTTING FUNGI.—II. 


Fic. 1.—Strands of mycelium of the ‘‘dry-rot”’ fungus, Merulius lachrymans, on the face of pine planks 
inalumber pile at Portland, Me. (the fungus has progressed to a height of six layers or more). FIG. 2.— 
The same fungus on the ground and in litter beneath an open storage shed, Philadelphia, Pa. 
Fic. 3.—Mycelium of a white Poria on the ground and on wood fragments beneath a cotton mill, 
Adams, Mass. Fic. 4.—Powdery deposit of spores cast by a mushroom over night (after Atkin- 
son). Fic. 5.—A species of Poria from a porch ceiling, Madison, Wis. Fic. 6.—Thin section of 
ct ener tine fruit body of Merulius lachrymans, showing palisade layer of basidia bearing spores 
after Falck). 


TIMBER STORAGE IN THE EASTERN AND SOUTHERN STATES, 9 


and sweep over the lumber, wetting it and depositing silt over great 
quantities of the stock (fig. 2). The writer has seen instances along 
the Atlantic seaboard where lumber stacks at least 12 feet high were 
thus silted completely to the top. A somewhat similar condition 
exists along certain rivers during times of flood (fig. 3), 

Where it is necessary to store lumber upon low swampy ground 
(figs. 4 and 5), the weed problem also becomes a serious factor. In 
the first place the growth of vegetation is so luxuriant as to require 
constant attention, and in the second place the ground is not even or 
firm enough to allow convenient mowing. The result is that some- 
times the weeds are allowed to develop above the height of the foun- 
dations, thus cutting 
off air circulation be- | ~ ee | 
neath the piles and 
hence increasing the 
danger from fungi 
many fold. 


QUALITY OF STOCK 
WITH REFERENCE 
TO DECAY. 


The fact that 
American mills are 
utilizing their timber 
to a smaller size than 
formerly throws a 
greater quantity of 
the inferior grades_ 
upon the storage 
yards. Rapid deter- 


P66F 


oration in this low- Fig. 4.—Lumber piled on low swampy land at a Texas 


grade stock may: re- sawmill. The serious decay in this yard is due to the 
r excess of soil moisture and poor circulation beneath 
sult unless it be care- the stacks. 


fully handled. Inthe 

case of many yellow-pine structural timbers it is a matter of common 
observation that the quality is growing decidedly poor, this being in 
large part due to the fact that small second-growth trees are being 
- logged and cut into dimension sizes. In the shortleaf-pine business, 
in particular, a single mill rarely attempts to cut both board and 
dimension stock. As a rule, it is said to be more profitable to cut the 
better grade larger shortleaf and loblolly trees into 1 and 2 inch 
stock. Hence, for structural sizes the trade largely depends on cer- 
tain timber mills, as well as a multitude of small portable mills 
operating in young second-growth timber. The storage of these less 

71022°—Bull. 510—17——2 


10 BULLETIN 510, U. S. DEPARTMENT OF AGRICULTURE. 


durable grades at times becomes a considerable problem, not alone at 
the mills but also in the retail yards. In fact, the writer has been 
told by certain retailers that deterioration due to decay in these low 
grades had become so serious with them that they had discontinued 
carrying such hazardous stock. 


In the case of hemlock, spruces, firs, low grades of pine, and cer-. 


tain of the less durable hardwoods, storage difficulties are bound to 
develop at times during exceptionally wet seasons, but much of the 
trouble can be fore- 
stalled by applying 
the proper methods 
of sanitation. 

It is necessary that 


enter into the con- 
struction of buildings 
it should be entirely 
free from fungous 
infection. Responsi- 
bility for clean lum- 
ber must rest with 
the lumberman. 


CONDITION OF 
STORAGE SHEDS 
AT MILLS. 


Re Spee: As noted before, 
Fig. 5.—Pine lumber piled in a swamp on high skids over 


standing water at New Orleans, La. Note the luxuriant Many mills, includ- 
vegetation, which checks proper air circulation beneath ing some of the larger 


the piles. ti 
ones, are operating 


under serious disadvantages of location as far as decay is con- 
cerned. The better types of storage sheds are inclosed at the sides, 
with ample ventilation beneath (fig. 6), but those open on both 
sides are not uncommonly met with. The exclusion of water from 
stored lumber becomes a necessity when such material is put in close 
piles under cover, where the drying action of wind and sun does not 
have full play. This is particularly true where sheds are built over 
low swampy ground where the vapors on rising from the wet soil are 
more or less imprisoned, keeping the air at a high humidity. A little 
extra moisture in such cases may be sufficient to permit the outbreak 
and rapid spread of fungous infections. 

The greatest source of danger in storage sheds lies in placing the 
lumber too close to the ground, and several instances have been noted 


if such material is to. 


ah ge 


TIMBER STORAGE IN THE EASTERN AND SOUTHERN STATES. Il11 


where widespread infections of some of the worst building fungi in 
the country have been prevalent in the foundation timbers and stored 
lumber in contact with them (PI. X, figs. 1 and 3). Many of the 
sheds over low ground have drainage canals beneath to carry away 
excess water, and in some instances, where the pitch of the ground is. 
not sufficient, stagnant water may accumulate over long periods. 
This may cause high humidities, approaching saturation, which per- 
mit the white cottony mycelium of wood-destroying fungi to develop 
rapidly over the surface of the timber. In general, it has been the 
experience of the writer that 
- moisture conditions around 
the foundations of storage 
sheds are often very favor- 
able to decay. 

Leaky roofs at times be- 
come a source of trouble. A 
few instances have come to 
the writer’s attention where 
comparatively small leaks 
have caused a considerable 
amount of visible, material 
decay in the upper parts of 
lumber piles. However, 
when we realize that in 
many cases the infection, on 
account of the short time in 
storage, does not have the op- 
portunity to cause marked Tic. 6.—Large storage shed at Laurel, Miss., set 
deterioration, but still is on concrete piers, high off the ground, with 
present in an incipient sta ge er ee nee eae sides. This is the 
ready to progress farther 
when placed under moist conditions, we can readily see the serious 
consequences which may ultimately accrue. 


P70F 


CONDITION OF STORAGE YARDS AT MILLS. 
GENERAL SANITATION. 


The vital necessity, viewed from the standpoint of decay, for abso- 
lute cleanliness around lumberyards is perhaps not fully appreciated 
by most lumbermen. The question of fire hazard, however, has led 
most mills to take certain steps in this direction which are of very 
great importance. These steps have usually assumed the form of 
keeping grass and weeds down, particularly in the dry season, e 
of removing rotten débris to a considerable extent. 


12 BULLETIN 510, U. S. DEPARTMENT OF AGRICULTURE. 


A broad survey of the lumber industry shows some instances where 


Fig. 7.—A small, very insanitary mill 

The conditions at this mill are a disgrace to the lumber 
Note the rotten, dilapidated tramway, the 
lumber stacks placed within 2 to 4 inches of the 
ground, and the débris scattered about and breeding 


industry. 


infection. . 


Any decaying tim- 
ber which has been 
allowed to accumu- 
late about the yards 
should be collected 
and burned. The 
mere carting of such 
débris to a conven- 
lent near-by pile (PI. 
ITT, fig. 1; text fig. 9) 
is not sufficient, for 
the fungi will con- 
tinue to thrive in 
such material for 
long periods and to 
produce fruit bodies 
which will liberate 
millions upon mil- 
lions of spores into 


mill in Louisiana. 


in Louisiana. 


absolutely no atten- 
tion is given to yard 
sanitation (fig. 7) and 
also a few other in- 
stances where the 
yards are sodded and 
handled like a well- 
kept lawn (fig. 8). 
The great majority, 
however, fall between 
these extremes. As a 
rule, grass and weeds 
are kept under fairly 
good control either by 
mowing or by pastur- 
ing. In most in- 
stances some rotting 
débris is scattered 
about. The factor of 
location often plays 
an important part in 
sanitation, for on 
swampy land the les- 
sened fire danger 
tends to encourage 
carelessness, 


P73F 
Fic. 8.—The well-kept grounds of a high-class longleaf-pine 


Practically all the lumber is run 


through the dry kiln and stored in large sheds, thus 
eliminating the problem of storage rots, 


j 


TIMBER STORAGE IN THE EASTERN AND SOUTHERN STATES. 13 


the air to infect whatever sound lumber may be in the vicinity. The 
writer has seen scores of instances where small piles of rotting débris 
have been scattered about lumberyards and even at times piled di- 
rectly against sound lumber (fig. 10). Very frequently this débris 
consists of old ties (fig. 11) or timbers from the tramway platforms. 
In other cases it may be yard stock which has rotted in storage and 
has been left in situ or carted a few rods and discarded just beyond 
the confines of the yard. One such mill yard was visited where 
several hundred 
thousand feet of pine 
and hardwood lum- 
ber had been thrown 
into an adjoining rice 
swamp in close prox- 
imity to and extend- 
ing for nearly a mile 
along a row of lum- 
ber stacks (see fig. 9). 
In this same yard it 
was also commonly 
noted that sound 
lumber fresh from 
the saw was piled 
upon the bases of old 
lumber piles which 
were thoroughly rot- 
ted (fig. 12). 

Also in this yard, 
as well as in a yard 
in Mississippi, vines 
were allowed to grow 


P74F 


up over some of the Fic. 9.—Pine and hardwood lumber which has rotted in 


lumber piles (fig. 13) ‘ storage in the yard shown in figure 11. Instead of burii- 
; ; >) ing the débris it was thrown into an adjoining rice 
This 1S, of course, swamp. Fungi developing on this débris will again 


highly objectionable infect the sound lumber. 
y) 
since such vegetation tends to collect moisture and impedes venti- 
lation. | 
Such conditions as these are bound to be a serious menace to the 
effective storage of lumber. 


TRAMWAYS AND RAILWAYS. 


Practically all sawmills have a more or less extensive tramway or 
railway system for the distribution of lumber from the mill to the 
yard and other units of the plant (fig. 14). It is quite the uni- 
versal condition that these structures harbor multitudes of various 


14 BULLETIN 510, U. S. DEPARTMENT OF AGRICULTURE. 


wood-rotting fungi, which cast off innumerable viable spores to be 
carried about by air currents to sound lumber. The elevated posi- 
tion of these fruit bodies on high tramways gives much greater 
facility to the wide distribution of their spores. 

Since the tramways require large amounts of timber in their con- 
struction, the use of wood preservatives in protecting them from 
decay is worth careful consideration. This would effect a direct 
saving both by prolonging the life of the timber and by preventing 
the development. of 
the fungous fruit 
bodies. 

In only one part 
of the tramway 
structure is decay 
secondary to other 
deteriorating fac- 
tors, and this is in 
the planking. Where 
the trucks or “bug- 
gies” operate con- 
stantly, the wear at 
the center very often 
nicely balances the 
decay at the ends, 
but even here, from 
the standpoint of 
sanitation alone, a 
light preservative 
treatment sufficient 
to immunize the tim- 


ar _-ver so that fungous 


Fic. 10.—Partially rotted hardwood boards piled against a fruit bodies ean not 


lumber stack. Infection will spread by contact to the - 
sound lumber, | develop is strongly 


recommended. 

The initial cost of constructing extensive tramways from 10 to 25 
feet high reaches a considerable figure, even at the actual mill cost of 
the timber. In the upkeep of these structures replacements are 
necessary as rapidly as the timbers fail, the resulting maintenance 
charges being a considerable item of expense. In none of the mills 
visited had thorough wood preservative treatments been applied. 
Partial attempts were noted in several instances, where brush treat- 
ments, usually of some patented coal-tar compound, had been applied 
at the joints. Ordinarily it is the more widely advertised trade prod- 


ucts which reach the attention of millmen. The cheaper preserva-. 


t 


PEt ee 


TIMBER STORAGE IN THE EASTERN AND SOUTHERN STATES. 15 


tives appear to be little known. In the opinion of the writer, thor- 
ough preservative treatments would effect an ultimate saving in 
maintenance charges, a considerable part of the cost of application 
being offset by the use of cheaper grades of timber, which when 
treated properly will last longer than the highest grade of natural 
wood available. 

In very few lumberyards are the railway ties preserved in any 
way. In most cases they consist of inferior timber which readily 
decays. Many fruit bodies of dangerous fungi are usually present 
(Pl. ITI, fig. 2), so 
that it is important 
from the standpoint 
of sanitation to re- 
move this source of 
infection by the ap- 
plication of wood 
preservatives, such as 
creosote or zinc chlo- 
mae! track in 
which the ties are 
creosoted is shown in 
figure 15. 


FOUNDATIONS. 


Probably no other 
factor involved in 
the storage of lumber 
in yards is open to 
more criticism from 
the sanitation stand- 


point than the foun- _ PT6F 
Fig. 11.—A highly insanitary mill yard in South Carolina. 


dations to the piles Hundreds of thousands of feet of stored lumber have 
(figs. 16 and 34). rotted in this yard as a result of these conditions. All 
this rotten débris should be removed and burned. 


Almost invariably 
these timbers are severely infected and often abundantly supplied 
with sporulating fruit bodies of serious wood-rotting fungi (Pl. ITT, 
figs. 3 and 4). 

Various types of foundations are in use. The most primitive and 
most insanitary type consists in laying planks directly on the ground 
and stacking the lumber upon them. This procedure occurs at only 
a few of the smaller mills. A few of the mills make use of built-up 
plank foundations (Pl. III, fig. 3), but the more usual method 
is to use 6 by 8 or 8 by 10 stringers, blocked up to a height of 


16 BULLETIN 510, U. S. DEPARTMENT OF AGRICULTURE. 


1 to 2 feet (fig. 16) or set on short posts. A few of the best mills 
make use of concrete piers for this purpose. The latter type of 
foundation would be greatly improved by the use of stringers treated 
with a wood preservative. 

The dangers arising from partially rotted foundations are evident, 
as has been seen from the earlier discussion of the activities of wood- 
destroying fungi. Where wood blocks are used to support the skids, 
fungi often progress directly from the moist soil upward, in this way 
frequently infecting the skids, thus adding the possibility of direct 

: mycelial infection to 
that of spore infec- 
tion. The infected 
skids themselves are 
dangerous, since the 
fungous mycelium 
can progress directly 
from them to the bot- 
tom of the lumber 
piles (Pl. IV, fig. 3; 
text fig. 17). Once 
started, and the 
weather conditions 
being warm and 
moist, such infections 
may pass through an 
entire stack. In con- 
sidering the menace 
of infected skids, we 
must also not lose 
sight of the fact that 
e7F such timbers are a 


Fic. 12.—Rotten base of an old hardwood stack upon a 
which sound lumber has been piled. This is a most prolific source of 
insanitary practice, as fungous infection will be spread fyyjt bodies (Pl. ITI, 
both by the contact of the diseased with the sound lumber : x 
and indirectly by the production of fruit bodies and fig. 3) with their 
spores, the latter blowing about, reaching sound mate- many spores, to be 
rial, and germinating to produce new infections. 


borne up into the 
lumber piles either directly by the wind or by convection currents 
which occur in relatively still air. The proof of this latter form of 
air currents is often before us in the form of rising mists or fogs. 

The first requisite in building foundations is to get them well off 
the ground, so as to allow ample ventilation beneath, which will 
dry out the timbers themselves as well as the soil below. A height 
of at least 24 inches from the top of the skids to the surface of the 
ground should be adhered to. 


ee ee 


oe 


Bul. 510, U. S. Dept. of Agriculture. PLATE lil. 


LUMBER SANITATION: WOOD-ROTTING FUNGI.—III. 


Fic. 1.—A pile of rejected hardwood logs which should have been removed or destroyed and not left 


to breed fungi (fruit bodies of 6 or 7 different organisms were identified from this pile). Fie. 2.— 
Lenzites berkeleyi fruiting on a hardwood tie. Fic. 3.—Hardwood pile foundations severely infected 
with Polystictus versicolor. Fia.4.—Daedalea quercina fruiting around a foundation block in a Penn- 
Sylvania storage yard. Fic. 5.—A badly infected piling stick in use at a Florida mill. Fia. 6.—A 
group of infected piling sticks at a Tennessee hardwood mill. Fic. 7.—Pile of 3-inch hard pine planks 
badly infected with Peniophora gigantea (a very common condition at Portland, Me.; the fungus is 
introduced from the South and develops rapidly in close piles). 


Bul. 510, U. S. Dept. of Agriculture. PLATE IV. 


LUMBER SANITATION: WooD-ROTTING FUNGI.—IV. 


Fic. 1.—Shortleaf pine which has rotted during 10 months’ storage in a retail yard at New Orleans. 
Fic. 2.—A structural pine timber which lay on the ground until severely rotted and was then thrown 
up into a pile of sound lumber. Fic. 3.—Mycelium of a wood-destroying fungus on the face of pine 
boards just uncovered in breaking down a pile (at a height of 6 to 8 boards from the bottom, but 
probably has gone much higher). Fias. 4 to 6.—Polystictus versicolor: 4, Upper surface; 5, lower sur- 
face; 6, plant growing on the end of a hardwood board ina lumber pile. lias. 7 and 8.—Polystictus 
hirsutus: 7, Upper surface; 8, lower surface. 


wae yl 


' tramways rebuilt be- 


TIMBER STORAGE IN THE EASTERN AND SOUTHERN STATES. 17 


The use of untreated wood blocking, particularly on low, moist 
ground, should be discouraged, as such material invariably harbors 
fungi. 

The most desirable practice, and one which would be free from all 
objections, is the use of concrete or brick piers, preferably the former, 
and skid timbers treated with some preservative. Such skids, about 
24 inches high, treated with creosote, are now in use at the Forest 
Products Laboratory 
(fig. 18). 

Foundations with 
concrete piers and 
untreated skids are 
at present in use in a 
number of yards and 
have given entire sat- 
isfaction. At one 
Mississippi mill (figs. 
14 and 19) unfavor- 
able conditions of 
low ground have been 
mainly overcome by 
good drainage, care- 
ful attention to the 
removal of débris, 
and the use of con- 
crete foundations 
well off the ground. 
A description of the 
foundations and their 
cost may be of in- 


terest. : ’ % . P78F 
* Fic. 13.—Vines growing over lumber piles. From a patho- 
The foundations logical standpoint this condition should be condemned, 
were placed and the because the dense foliage prevents the lumber from rap- 
idly drying out after rains, thus promoting decay. 


tween 1908 and 1910, after a number of years of unsatisfactory expe- 


rience with wood, at a reported cost of about $30,000 for a mill having 


an annual cut around 60,000,000 feet of pine a year. In the two years 
preceding the placing of the concrete foundations and the rebuilding 
of the tramways, the annual charge for material and labor in the 
upkeep of the yard was $18,000 and $17,000, respectively. Follow- 
ing the equipment of the yard with concrete foundation piers and 
concrete footings for the tramway posts, this charge was materially 
reduced. The present maintenance cost as reported by the company, 


71022°—Bull. 510—17——3 


18 BULLETIN 510, U. S. DEPARTMENT OF AGRICULTURE. 


~PT9F 

Fie 14. Zs oral view of a mill yard in Mississippi, show- 
“ing conerete pile foundations and tramway footings. 
_The ditch assists materially in draining the yard. No 
débris is°allowed to accumulate. The stacks are high 
off the ground and amply ventilated beneath. The tram- 
way and pile foundation timbers would be improved by a 
_ preservative treatment’ with creosote. 


mind the advantage 
gained in preventing 
deterioration in the 
stored lumber itself, 
due to improved sani- 
tation. While this 
item is very difficult to 
estimate, the company 
believes it a very ap- 
preciable asset of its 
storage practice. 

The approved type 
of concrete foundation 
pier now in use by this 
company is of the form 
illustrated in figure 20, 
consisting of a_ base 
block 3 feet square, 
tapering upward and 
cast in position. Upon 
this base block is cast 


based on a consump- — 


tion of 600,000 feet 
of timber a year at a 
value of $12 per 1,000 


feet b. m., is $7,200, 


or 12 cents per thou- 
sand of millcut. The 
timber used consists 
of pine heart seconds 
having an average 
life of 5 to 6 years 
and a maximum life 
of 8 to 10 years for 
material not in con- 
tact with the ground; 
pile foundations and 
tramway footings 
average 4 to 5 years. 
In addition to the 
direct saving in main- 
tenance charges, we 
must also keep in 


— PIOSF 
the top block, y) feet Fic. 15.—A clean, sanitary retail yard, having concrete 


foundations throughout and creosoted ties in the rail- 
square and also taper- raat tence 


_— _~— Pi 


the piers in two 


at heights never less 


TIMBER STORAGE IN THE EASTERN AND SOUTHERN STATES, 19 


ing upward, being 1 foot square at the top, which gives a good bear- 
ing surface for the horizontal wooden skids or for the vertical posts 
where it is necessary to elevate the skids to a height consistent with 
the height of the tramways. 

A concrete mixture of 1-21-5 is used, at a cost for labor and ma- 
terial of $5 per cubic yard, or an average cost of about $5 per pier. 

The foundations follow the slightly varying contour of the ground. 
To compensate for the more marked differences in soil elevation 
the skid timbers are frequently blocked up to an approximately level 
condition by the use of short sections of pine pgsts treated at the 
ends with a tar or 
cresote preparation. 

There are two ad- 
vantages in casting 


pieces: (1) The re- 
duction in weight of 
the individual blocks 
when it becomes nec- 
essary to shift them 
about the yard, and 
(2) the greater ease 
of alignment when 
erecting the skids. 
All the skids are 
well off the ground 


P380F 
than 18 to 24 inches Fic. 16.—Thoroughly rotted pine skids in a mill yard in 
Texas. Such decayed foundation timbers are very com- 
and frequently 36 mon. Fungous infection can pass directly from these 
inches and over. The timbers to the lumber piled on them. Creosote would 
have prevented this condition. 


lumber is not piled 7 2 
directly on the wooden skid timbers, but rests on a 1-inch pine strip, 
usually about 3 inches wide, to give.a smaller bearing surface. This 
method is not uncommonly employed in various yards. It is of 
distinct advantage where lumber is piled on infected skids, and if the 
dry strips are freshly laid for each pile they materially assist in 
reducing infections in the base of the stack. 

In direct contrast to these concrete foundations with ample venti- 
lation beneath, one frequently meets with the type illustrated in 
figure 21. The one figured is built of 2-inch pecky cypress planks 
about 14 feet long, resting directly on the ground. The amount of 
lumber used was computed for one of the squares and totaled ap- 
proximately 585 feet b. m. While pecky cypress is often used in the 
South for foundations of this type, in many other cases either non- 


20 BULLETIN 510, U. S. DEPARTMENT OF AGRICULTURE, 


durable hardwoods or the cheaper grades of pine are used. Decay 
is often serious in such foundations. There is very little chance for 
ventilation, and this often leads to storage rots in the base of the 
piles. | ith 

The open type of foundation is always much the better from a - 
pathological standpoint. In certain of the Gulf cities, where munici- 
palities in cooperation with the United States Public Health Service 
are making strong efforts to get rid of rats to safeguard against 
the bubonic plague, certain ordinances have been passed requiring 
structures to be yaised at least 12 inches from the ground and left 
open beneath. This requirement will react very favorably upon — 
lumber storage, for the first 
necessity is to get the timber 
off the ground, with ample 
ventilation beneath. Figure 
22 illustrates the method of 
elevating the skids em- © 
ployed in a retail lumber- — 
yard at Mobile, Ala., which 
has only recently occupied 
the premises. 

Timber foundations are 
frequently the cause of con- 
siderable trouble on account 
of decay failure under heavy 
loads, thus allowing the 
piles to.topple over or to 
crush to the ground, where 
they have every opportunity 
. to rot. Figure 23 shows two 
Tie 17a 12 by 12 Asch inbeoaine oe such piles at a South Caro- 

showing a rotten hole in the face which lay in lina mill. Rot in founda- 

contact with infected skids. . tion timbers is extremely 
common and, in fact, has been encountered in practically every yard 
examined where timbers are employed for this purpose. 


PILING STICKS. 


Practically all yards in which the lumber is “ stuck” fail to appreci- 
ate the necessity of keeping the sticks free from infection. The strong 
tendency is to scatter them about on the ground wherever they hap- — 
pened to fall when the previous piles were taken down (fig. 24). In 
a very few yards attempts are made to improve the appearance of the 
premises by gathering the sticks endwise into conical piles or by 
stacking them carefully on the ground beneath the skids (fig. 25). 


a“ 


TIMBER STORAGE IN THE EASTERN AND SOUTHERN STATES. 21 


This question of the sanitary handling of the piling sticks is of 
very great significance, particularly in regions of high humidity, 


where every precau- 
tion must be taken 
to safeguard stored 
lumber. Plate III, 
figures 5 and 6, shows 
such infected sticks 
found in Florida 
and Tennessee lum- 
beryards, where sev- 
eral species of wood- 
destroying fungi 
were frequently 
noted in the piles. 
When one keeps in 


‘mind the fact that 


the soil in and about 
lumberyards often 
becomes, in the 
course of time, thor- 
oughly intermixed 
with sawdust and 


P82F 


Fig. 18.—Pile foundations consisting of creosoted timbers 


resting on concrete piers in use at the Forest Products 


Laboratory, Madison, Wis. 


type of foundation. 


This is a yery satisfactory 


partially decomposed woody matter which offers a fertile field for the 
development of wood-destroying fungi, the necessity of keeping all 


bers in general use in a mill yard at Laurel, Miss. 


P83F 
Fie. 19.—Concrete foundations with untreated skid tim- 


Only 


two rows of piers are used for stock 14 feet or less in 


length. 


sound material out 
of contact with it be- 
comes very evident. 
In cases where saw- 
dust and bark or 
wood débris are used 
to produce artificial 
fills the danger is 
further increased. 
Such filling mate- 
rials are not infre- 
quently used. 

Such situations in- 


~troduce the further 


question as to what 
material should be 
used for filling in 


low portions of the yards. While the material used will necessarily 
be governed largely by local conditions, it is the opinion of the writer 


22 BULLETIN 510, 


‘ 


U. §. DEPARTMENT OF AGRICULTURE, 


that clean clay or sandy soil will serve the purpose admirably. While 


sandy soil allows fungi to spread within it more rapidly than clay, 


it offers the advantage of rapid seepage, and where the surface is 


amply ventilated no 
difficulty should be 
experienced. (PI. X, 
figs 1 and 3.) 
‘The principal need 
is to have the yards 


face water will not ac- 
cumulate. Ordinary 
ashes are not consid- 


or surfacing material, 
since they absorb 


Fic. 20.—Sketch of a concrete foundation pier in use in Moisture readily and 


a mill yard in Mississippi. 


for convenience in aligning and moving about the yard. 


It is cast in two sections, 


hold it tenaciously, 
particularly when 


they are ina finely pulverized condition. Less finely divided mate- 
rial, such as coarse cinders, gravel, or slag, is better adapted on 


account of the rapid 
appear to grow 
through ashes quite 
readily when they 
are in a moist condi- 
tion. In fact, the 
writer has a record 
of one case where 
fungi developed lux- 
uriantly in a pile 
of ashes in the open 
when _ exposed _ to 
prolonged rainy 
weather. (Pl. IX, 
fig. 3.) 


METHODS OF STACKING 
LUMBER. 


Lumber piled in 
the open must be al- 
lowed _ ventilation 
around the individ- 


seepage. Moreover, wood-destroying fungi 


| 


 POLICRE ENS ar Fs ne en 


P84F 
Fic. 21.—Pecky cypress foundations in use at a mill in 
South Carolina. Each large square contains from 500 to 
600 board feet. This type of construction does not 
allow sufficient ventilation beneath the piles. 


ual pieces, and this is usually arranged for in storage pragetice. 
In some instances, however, this necessity is ignored in certain 


so laid out that sur-— 


sidered a good filling 


TIMBER STORAGE IN THE EASTERN AND SOUTHERN STATES. 23 


retail yards where it is the custom to dispose of the stock within 
very short periods, say, two or three months. In some of. the 
northern retail yards along the Atlantic coast, where southern pine 
comes in by boat in a comparatively green condition, this prac- 
tice often leads to severe fungous infections throughout. entire 
piles. This infection undoubtedly gets a good start in the hold 
of the vessel during transit and propagates- further when close 
piled in congested lumberyards. Such a pile of diseased pine is 


‘ 


P85F 
Fre. Aa. Se maaehitions at Mobile, Ala., built to conform to an ordinance requiring all 
“structures to be raised at least 12 inches off the ground and left open underneath. 


shown in Plate III, figure 7, where the infection extends up high 
into the stack. 

It is not the intention in the present bulletin to enter into a dis- 
cussion of detailed methods of stacking lumber. The primary con- 
cern, from the standpoint of sanitation, is to dry the lumber as 
rapidly as possible and maintain it in this condition. However, 
other considerations, such as checking and warping, must be taken 
into account in many instances. The humidity or dryness of the 
chmate will be of great weight in determining the proper amount 
of ventilation to give the best results from all standpoints, 


24 BULLETIN 510, U. 8. DEPARTMENT OF AGRICULTURE, 


Certain general considerations, however, apply to practically all 


cases. ‘The method of using special narrow cross sticks is probably 


this offers certain 
advantages when the 
sticks are handled in 
a sanitary manner. 
In the first place, the 
strips are kept in an 
air-dry condition, 
which offers consid- 
erable advantage 
over green material; 
in the second place, 


row, do not offer a 
bearing surface 
Fie. 23.—Foundations which! have failed through ne sb than 1 to 4 
permitting the piles to topple over. This would have inches wide. A dis- 
been prevented by the use of a good preservative. tinct advant age 
would also accrue with the use of sticks cut from highly durable 
material; for instance, resinous heart pine or resistant hardwoods, 
such as white oak 
and heart red gum. 
The second gen- 
eral method of. pil- 
ing lumber consists 
in using the nar- 
rower widths of the 
lumber itself for 
crossing strips (fig. 
26). -The wider 
boards ordinarily 
offer too much of a 
bearing surface for 
good air circulation. 
At one of the Arkan- 


=| etc . P87F 
sas mills visited a Fic, 24.—Piling sticks lying on the ground at a mill in 
was customary in South Carolina, showing the insanitary method of han- 


. dling them. Such sticks lying for only a week or two in 
the earlier days to contact with fungus-infected ground may themselves 
use the regular run become seriously infected, and decay may in turn pass on 


of lumber up to 12 to the lumber stacks. 

inches wide as crossers, but this practice was discontinued on account 
of the serious loss from decay. The manager of the mill informed 
the writer that considerable rot would occur in 8 to 12 inch stock 


in greatest use, and 


_ the strips, being nar- 


TIMBER STORAGE IN THE EASTERN AND SOUTHERN STATES. 25 


within a year under such conditions. The present practice is to use 
strips 4 inches wide and 1 inch thick of air-dry No. 2 pine. This 
method has proved entirely satisfactory. 

In laying sticks careful attention should be paid to placing the 
successive strips vertically one above the other. If they are placed 
hit or miss, certain ones may fall in the span of the next tier below, 
thus producing much unnecessary warping of the lumber, due to 
the pressure of the overlying layers. 

In all cases of flat piling of green lumber care should be taken to 
leave a space of:at least half an inch between the edges of the stock. 
This gives a vertical air circulation, which is particularly effective. 


ene P88F 
Fig. 25.—Piling sticks placed on wet ground beneath the skids, In order to keep them 
free from infection, such sticks should never be placed in contact with the soil. 


Two other methods of piling 2 to 3 inch stock are used to some 
extent with good results. The edge piling of 2 by 4’s (fig. 27), 
sticking the pieces in the usual way, has given good results at several 
mills where flat piling produced an appreciable amount of deteriora- 
tion. The method of fiat piling without the use of sticks, occasion- 
ally employed with 2 by 6’s, in which horizontal circulation is pro- 
vided for by leaving wide spaces between the edges of the stock 
(fig. 28), would not appear to offer as good opportunities for drying 
lumber in a moist climate as the more usual method which makes use 
of sticks. 


4 


°6 BULLETIN 510, U. 8. DEPARTMENT OF AGRICULTURE. 


Besides the proper sticking and lateral spacing of lumber, a cen- 
tral flue one board wide running vertically through the middle of 
the pile is often of decided advantage. Many millmen recognize 
this as good practice, but few of them consider they have sufficient 
yard space to carry 
out the method con- 
sistently. 

Another factor 
which enters into the 
storage of lumber is 
the piling of stock in 
even or approximately 
uniform lengths (see 
fig: 26). A few mills 
consider that such pre- 
lhminary sorting is 
feasible from an eco- 
nomic standpoint, on > 
account of the greater 
facility with which 
such stock. can be 
billed out. From a 
—— pathological stand - 


‘Fic. 26.—Lumber piled in even lengths in a southern point the. practice is 


mill yard. The crossing strips consist of the narrower highly commendable. 
widths of lumber. 


Wah tangy 
ity 


h 
ANY \ . i 
A 


yi 


ae 


LRT 


My : iLL ti | 


eres 


WA 


4 b ang Rais 


| Uneven lengths allow 
rains to beat in, and also offer convenient and favorable lodging 
places for fungous.spores. Likewise, marked disparities in length 
permit considerable warping of the ends, which often project out 
several feet from the main body of the pile. Figure 29 shows this 
condition in an exag- Se. 
gerated form. To. eee 
protect the ends of f MMOS 
the lumber from TH AAN\\\ 
beating rains as far 
as possible, the cross 
strips should be 
placed at least flush [PA Oe eS 5 oo 
with the ends, both in Shae 


d bal ind Fig. 27.—Edge-piled 2 by 4 pine atan Arkansas mill. This 
front an enna. method of piling permits better vertical air circulation | 
There still remains and consequently more rapid drying and less danger 


: . from decay during storage. 
the question of roof- fi | 


ing the piles. The commonly accepted pitch for lumber piles is 1 
inch to the foot, and with a loose roof of lapped boards the greater 
part of the rainfall will drain away. The roofs must necessarily 
extend somewhat beyond the piles, in order to carry the drip clear of 


Fk ee ee ig 


TIMBER STORAGE IN THE EASTERN AND SOUTHERN STATES. 27 


the stack at the rear. Roofing the piles should never be omitted, as 
the protection afforded against rain is of undoubted value and the 
operation itself adds very little to the cost of piling. 


HANDLING TIMBER AT RETAIL YARDS. 


The storage problems involved at retail yards are somewhat dif- 
ferent from those at mills, although they may be discussed under 
exactly similar heads. 
| LOCATION OF YARDS WITH REFERENCE TO DECAY. 


As a first observation, we may say in general that retail or whole- 
sale yards, as opposed to yards in connection with a sawmill, have the 
advantage of a higher and drier _ 
location, which, in turn, should 
make sanitation measures easier 
to practice. The necessity of lo- 
cating on streams or bodies of 
water is not ordinarily a prime 
consideration, but rather the lo- 
cation on or near a railway line 
and as convenient as possible to 
the actual consumer. Naturally, 
in the seaport towns, where much 
of the lumber comes in by boat, 
the most favorable location from 
the standpoint of transportation 
is along the water front, but. in 
inland towns, where the shipment 
of lumber is by rail, the other 
factors of accessibility to the 
local market and the price of 
land play the important part. 

This general advantage of lo- 


P9IF 


cation, however, is often consid- Fie. 28.—Two-inch stock piled without 


erably offset bv th 4S] sticks, a method rarely used in the yards 
4 ¥ 3 necessity for visited. Not used, as far as observed, 


close piling, without adequate with stock less than 6 inches wide. 
ventilation either between the : 
piles or through them, due to the higher cost of land. When this is 
coupled with the fact that much of the product has been in storage 
elsewhere for varying periods, sometimes a year or more, it can 
readily be seen why decay is rather frequently encountered in the 
retail yard. , 

The salvation of the retail dealers usually lies in disposing’ of their 
stock rapidly. Most of them aim to turn it at least three or four 
times a year, for they recognize that long storage will prove disas- 
trous. Timber showing deterioration through decay is not difficult 
to find in most retail yards. However, this is very often only in the 


e 


28 BULLETIN 510, U. S. DEPARTMENT OF AGRICULTURE. 


incipient stage and is not readily noticed by the casual observer. 
Yards which dress the lumber just’ before filling orders can in this 
way supply to the trade clean-looking lumber, but this does not 
always imply freedom from fungous infection. The opinion seems 
to be prevalent among many lumber dealers that the mere brightening 


of the lumber by running through the planer serves to remove all © 


objection to infected stock. This is far from the fact, however. It 
merely gives it a better sale appearance, and the danger to the ulti- 
mate user still remains. The adage that “ beauty is only skin deep ” 
‘ applies to such infected stock with particular force. 

While perhaps the majority of lumber dealers have merely over- 
looked the full significance to the building trades of the dangers 
which lurk in diseased stock and are trying in every way to satisfy 
their trade and meet competition, there still remain a considerable 
number who do not look into the future but are content to get the 
stock off their own hands without any care as to the service which it 
will give the constmer. This is a thoroughly mistaken policy, for 
the lumberman 
should in every way 
strive to increase the 
value of his product. 
In the first place, it 
is good business pol- 
icy, and, second, 
there remains the 
question of moral 
and legal responsi- 
bility. 


P9oF STORAGE SHEDS. 
Fic. 29.—A stack of pine lumber of uneven lengths. Note 
the irregular distribution of the piling sticks and the In many retail 


consequent warping and twisting of the boards. 


tions are very poor. The closed type of shed is in the minority. 
Since lumber under cover is as a rule piled closely in bins, the need 
for ample ventilation beneath and a tight roof above is imperative. 
All the decay observed in lumber sheds is directly traceable to one or 
the other of these factors; mainly, however, that of improper ventila- 


tion. It has frequently been the custom merely to lay a narrow timber. 


sill directly on the ground, or at best within a very few inches of it, 
to serve for the foundation (fig. 30). The best practice, however, has 
been to place the sills on brick or concrete piers not less than 18 to 24 
inches high, running the siding of the shed only to the bottom of the 
sills, so as to allow a free circulation of air regardless of the direction 
of the wind. Such a construction is represented in figure 31. 


Another defect of the open shed which has been frequently noted | 


is the strong tendency to allow the ends of the longer stock to project 


yards shed _ condi- 


; 


TIMBER STORAGE IN THE EASTERN AND SOUTHERN STATES. 29 


beyond the eaves (fig. 32). Very few sheds are equipped with gut- 
ters (fig. 31), andthe drip during rains may run back along the 
projecting pieces well into the center of the piles. When once 
wetted the close piles will retain this moisture for long periods, 
during which a serious outbreak of decay may be initiated. 

A few cases of severe outbreaks in retail lumber sheds will be de- 
scribed and illustrated later. 

YARDS. 


On account of very limited storage space, nearly all retail yards 
fail to observe the proper spacing of lumber to insure ample ventila- 
tion. The general tendency is to pile altogether too close to the 
ground for safety, and in many instances the lumber is not spaced 
as well in the piles as 
it should be (fig. 33). 
The principal danger 
lies in the foundations, 
which are very often 
seriously infected with 
rot (fig. 34) or are not 
adequately constructed 
to insure proper venti- 
lation. The danger in 
allowing lumber to 
come in contact with 
the soil is evident in 
figure 35. As the ques- 
tion of foundations in 
mill yards was dis- 
cussed in considerable 


detail earlier in this posF 
Fic. 30.—An old, dilapidated shed on the Mobile River 


publication and since in which the lumber is too close to the ground. Many 
the fundamental con- seyere cases of rot have developed under just such 


siderations apply with ‘"™"°"* 

equal force to retail yards, only certain features which serve to 
connect these fundamentals with the direct problems of the retail 
yard will be added here. 

Many retail lumber yards use solid or latticed foundations of 
built-up plank running parallel to the alleys (figs. 86 and 87); 
others resort to wood blocking for the support of the skids. The 
use of concrete is very limited, but has given complete satisfaction 
wherever introduced. It is usually laid down as solid foundations 
parallel to the alleys. In one yard at Birmingham, Ala., the founda- 
tions were 8 to 10 inches high, 6 inches thick at the top, and placed in 
triple parallel rows spaced 7 feet apart (fig. 38). The advantage of 
reinforcing the concrete is well shown in figure 39. 


30 BULLETIN 510, U. S. DEPARTMENT OF AGRICULTURE. 


Somewhat higher foundations than these are to be preferred in 
many situations, but in this yard, where every precaution was taken 
to keep the ground free from all infected débris, and where the 
drainage was excellent, this height has proved satisfactory. 

Piers have the advantage over a solid wall in permitting better 
ventilation, but piers also involve the use of wooden skids, which if 
not treated with a good preservative may more than offset the ad- 
vantage gained in better ventilation. 

The careless handling of crossing: sticks and lumber in retail yards 
is just as evident as in 
mill yards. The gen- 


of the yards visited is 
to throw sticks about 
on the ground when 
.the stacks are torn 
down, and there they 
often remain until 
they are needed again. 
This insanitary prac- 
tice needs no. further 
comment. A compari- 
son of the yard shown 
in figure 40, where the 
lumber is scattered 
about promiscuously 
on the ground, with 
the yard shown in fig- 
ure 15, where concrete 


PO5F 


Fic. 31.—A retail shed in’ Tenbealer! well roofed, pro- foundations and treat- 


vided with gutters, and set on brick piers with ample 


ventilation beneath from all sides. ed ties are In use and 


all débris is carefully 
collected into a wagon (fig. 41) and hauled away, may be of interest 
in this connection. 


FUNGI WHICH ROT STORED LUMBER. 


A considerable number of different species of wood-destroying 
fungi have been encountered in lumberyards. These, of course, are 
more frequently found fruiting on the foundations, tramway timbers, 
and ties than on the stored lumber, but this is only a question of the 
time which the timbers have been in the yard. The fact that elevated 
tramway posts and girders will rot in the South in a few years is 
proof conclusive that lumber stored in the open will also rot if it 
becomes necessary to hold it in storage too long. In the Gulf States 
low-grade lumber stored in the ordinary manner will show consider- 


eral practice in many > 


—_—-)h eee — ee — ae ae 


within a comparatively 


TIMBER STORAGE IN THE EASTERN AND SOUTHERN STATES. 31 


able deterioration within a year. Plate IV, figure 1, shows a small 


pile of shortleaf pine seriously rotted after a period of only 10 


months in a retail yard at New Orleans; in fact, the owner of this 
yard suffered so much loss from decay in the less durable grades of 
pine that he has discontinued handling them. 

Fungi are in evidence in lumberyards in the vegetative stage 
(moldlike growths; Pl. I, fig. 1, and Pl. IV, figs. 2 and 3) and in 
the fruiting stage. Almost any species occurring in a given region 
may occasionally be introduced into storage yards, but the great 
majority of the speci- 
mens found fruiting fall 


few species. 

One of the common 
forms, Polystictus versi- 
color (L.) Fr., is shown 
in Plate IV, figures 4, 
5, and 6, growing both 
from the ends of stored 
hardwood. lumber and 
from built-up plank 
foundations (PI. III, 
fig. 3). This organism 
is profusely distributed 
throughout the entire. 
United States_and is 
more destructive to 
hardwood timber than 
any other fungus. 

Other members of this 
genus, such as Poly- |e 
stictus hirsutus({Schrid.) pos 
Br. (PL IV, figs. 7 and #9, 924 rll sed in alabame tn vote the Ta 
8), P, pargamenus Fr. from rains. This condition favors decay when the 
(PL. V; figs. 1 and oye water runs back along the boards into the piles. 
and P. abietinus Fr. (Pl. V, figs. 3 and 4) are likely to be found in 
most lumberyards throughout the United States, occasionally fruit- 
ing on stored lumber, but more often causing sap rots of tramway 
timbers, foundations, and ties. The last species grows on coniferous 
timber almost exclusively; the other two on hardwood timber. | 

Among other members of the true pore fungi may be mentioned 
Polyporus adustus (Willd.) Fr. (Pl. V, figs. 5 and 6), which is usu- 
ally thin, tough, and leathery, creamy above and smoky below; 
P. sanguineus (L.) Fr. (Pl. VI, fig. 4), of a bright red through- 


32 BULLETIN 510, U. S. DEPARTMENT OF AGRICULTURE. 


out, shiny above, rather thin and shelflike, which is found abun- 
dantly throughout the South on hardwood timbers; and P. gilvus 
Schw. (Pl. VI, figs. 2 and 3), a firm, comparatively thin, rather 
rigid species, yellowish within and reddish brown without as it ages. 

In the northeastern United States one occasionally finds on oak 
or chestnut timbers the heavy, tough, corky fruit bodies of Daedalea 


quercina (l.) Pers. (Pl. VI, fig. 1). When the plant develops nor- 


mally it forms large and sinuous pores, but in lumberyards it more 
often appears as abortive clay-colored cushions (Pl. III, fig. 4). It 
is one of the few fungi which attack white oak and chestnut. 
Another destructive group of fungi is represented by the genus 
Lenzites. Among the brown species there are three principal. ones to 
be feared: Lenzites 
sepiaria (Wulf.) Fr. 
(Pl. VI, figs. 5 and 
6),.L. berkeleyi Sace. 
(Pl. VI, fig. 7), and 
L. trabea (Pers.) Fr. 
(Pl. Vase ya 
The first two con- 


ous enemies of conif- 


ber in the United 
States. The last spe- 
cies rots both the 
heartwood and sap- 
wood of many differ- 
ent kinds of hard- 
woods. All three are 
Fig. 338.—A very congested retail yard at New Olieans, Las brown throughout 

showing lumber temporarily placed on the ground in solid and leather 22 to 


piles. This is a bad practice, because under such condi- corky in texture. In 
tions decay may start in a very short time. 


some fruit bodies the 
under surface may consist of distinct gills; in others, the gills may 
more or less run together to form sinuous to subcircular pores, easily 
visible to the naked eye. 

Another species, Lenzites betulina (L.) Fr. (Pl. VII, figs. 2 and 3), 
of a general creamy color, with an upper surface frequently banded 
with shades of yellow, orange, and brown, occurs on hardwood tim- 
ber throughout the United States. It has commonly been noted in 
lumberyards on timbers used in various structures. In one large 
mill yard where oak was largely used for planking the elevated tram- 
ways, this species, in conjunction with Polystictus versicolor, suc- 


stitute the most seri-_ 


erous structural tim- » 


f 


Bul. 510, U. S. Dept. of Agriculture. PLATE V. 


LUMBER SANITATION: WOOD-ROTTING FUNGI.—V. 


Fias. 1 and 2.—Polystictus pargamenus: 1, Upper surface; 2, lower surface. Ficas.3 and 4.—Polystictus 
abictinus: 3, Typical form from a pine log; 4, plants showing upper and lower surfaces, Fias. 5 and 
6.—Polyporus adustus: 5, Upper surface; 6, lower surface. 


Bul. 510, U. S. Dept. of Agriculture. PLATE VI. 


LUMBER SANITATION: WOOD-ROTTING FUNGI.—VI, 


Fic. 1.—Daedalea quercina growing on an oak tie. Fia@s, 2 and 3.—Polyporus gilvus: 2, Upper surface; 
3, lower surface. Fia. 4.—Polyporus sanguineus, paper surface. Fics. 5 and 6.—Lenzites sepiaria: 
5, Upper surface; 6, lower surface. Fic. 7.—Lenzites berkeleyi, upper and lower surfaces. 


Bul. 510, U. S. Dept. of Agriculture. PLATE VII. 


LUMBER SANITATION: WoOOD-ROTTING FUNGI.—VII. 


Fig. 1.—Lenzites trabea, upper and lower surfaces. Fias. 2 and 3.—Lenzites betulina: 2, Lower sur- 
face; 3, upper surface. Fic. 4.—Lentinus lepideus, typical form on railway ties. 


Bul. 510, U. S. Dept. of Agriculture. PLATE VIII. 


LUMBER SANITATION: WooD-ROTTING FUNGI.—VIII. 


Fia. 1.—Lentinus lepideus, under surface. Fic. 2.—Schizophyllum commune, upper and lower surfaces. 
Fias. 3 and 4.—Stereum fasciatum: 3, Upper surface; 4, lower surface. Fics. 5 and 6.— Coniophora 
putcana: 5, Smooth form growing on spruce sheeting in a mine; 6, warted form from a mine. 


ee 


Bul. 5.u, U.S. Dept. of Agriculture. PLATE IX. 


LUMBER SANITATION: WooD-ROTTING FUNGI.—IX. 


Figs. 1 and 2.— Merulius lachrymans: 1, A well-developedfruit body with porous moisture-conducting 
strand (from a residence in Pennsylvania); 2, mycelium growing over the surface of the rotten wood. 
Tics. 3 and 4.—An unidentified fungus in a Mississippi cotton warehouse; 3, flooring rotted hy the 
organism; 4, fruit bodies developing on other parts of the floor. (This is the same species illus- 
trated in Plate X, figures 1 and 2.) 


Bul. 510, U. S. Dept. of Agriculture. 


PLATE X. 


LUMBER SANITATION: WooD-ROTTING FUNGI.—X., 


Fics. 1 to 4.—A severe infection of an unidentified fungus in an Alabama lumber yard: 1, Open shed 
where the fungus has progressed upward to the second bin, 5 feet from the ground; 2, corner of closed 
shed on the same premises where rolls of tarred roofing paper resting on the floor (not shown in the 
picture) were severely rotted at the ends; 3, the shed shown in figure 1, showing how the infection 
started by piling too close to the ground over a cinder fill; 4, the same shed after the lower bins had 
been raised in an effort tocontrol thespread ofthe rot. Fics. 5 and 6.—Peniophora gigantca: 5, Inter- 
mixed with molds and developing on moist pine shingles in a close pile in a Tennessee retail yard 


(growth, which an antiseptic dip at the mill would have prevented, had started during transit); 
6, the mature stage growing on a pine log. 


TIMBER STORAGE IN THE EASTERN AND SOUTHERN STATES. 883 


ceeded in rotting the planks at practically the same rate at which 
they wore down mechanically. 
Of the true gill fungi may be mentioned two species—Schizophyl- 
lum commune Fr. (Pl. VIII, fig. 2) and Lentinus lepideus Fr. (P1. 
‘VII, fig. 4, and Pl. VIII, fig. 1). The former occurs everywhere in 
the United States on both coniferous and hardwood timber. It is 
white to grayish, very thin and flexible, woolly above, and has very’ 
distinct gills below, which are split longitudinally at the edge and 
each half curled over, much as a dandelion stem curls when split. 
It is a comparatively 
small. fungus, usually 
not projecting out 
more than 1 or 14 
inches. At times it is 
attached at the center 
of the back and then 
presents a circular out- 
line with the gills ra- 
diating from a common 
center. When dry it is 
much curled and in- 
rolled, but during 
rainy weather it readily 
revives and appears 
fresh and expanded 
again. Fortunately, it, 
deteriorates wood but 
slightly and need occa- 
sion no fear among 


lumber users. | ae ae 

Lentinus lepideus Fr. Fis. 34.—Built-up pine foundations in a retail yard in 
F Tennessee. Many of the foundation timbers are seri- 
IS a fungus of the ously decayed and infection may pass to timbers piled 
“toadstool ” type, with in contact with them. Figure 17 shows what hap- 


- l b dl pened to a structural timber placed on a foundation 
a circular, roa y in this yard similar to these. 


convex, scaly cap, anda 4 

stout, fibrous, central or eccentric stem. It is white throughout, 
except for the brownish scales on the upper side of the caps and on 
the stem. The under side is provided with coarse gills, which become 
considerably toothed and split as the plant ages. 

This fungus is a very rapid grower and primarily attacks timber 
in contact with the soil. It rots pine railway ties very rapidly, 
growing through sandy soil from one stick to another. Serious out- 
_ breaks of the fungus in pine warehouse floors have been reported 
_ several times, and it should be carefully guarded against in lumber 
\ storage yards. : 


34 BULLETIN 510, U. S. DEPARTMENT OF AGRICULTURE. 


Of the fungi having a smooth under surface, two species are 
common enemies of structural timber—Sterewm fasciatum Schw. 
(Pl. VIII, figs. 3 and 4) and S. lobatum Knze. These fungi are 
too much alike for the layman to attempt to distinguish between 
them. They are very thin and flexible, the individual shelves often 
growing one above the other. The general color is grayish to creamy., 

Among the incrusting forms three deserve particular attention, 
viz, Merulius lachrymans (Wult.) Fr., Coniophora puteana (Schum. ) 
Fr. (=C, cerebella (Pers.) Schrot.), and Pentophora gigantea (Fr.) 
Mass. The first two species are notoriously dangerous and have been 
found in a number of lum- 
beryards extending from 
Massachusetts to the Gulf 
of Mexico. They are also 
the most frequently re- 
ported of all fungi occur- 
ring in buildings, and also 
the most destructive. 

Merulius lachrymans 
(Pl. IT, figs. 1,-2, and’6, 
and Pl. IX, figs. 1 and 2) 
is a soft, subgelatinous 
fungus, forming a brown, 
crumpled growth with a 
white, fluffy margin over 
the surface of timber. As 
it develops it produces 
dirty gray to brownish 
minutely porous strands, 
which serve for the con- 
i] duction of water, thus en- 

fay px abling the fungus to 

Fis, 35.Proteting ends of Iumber which 8 0% spread rapidly over com- 

paratively dry substrata. 

For this reason it has been frequently termed the “ dry-rot fungus.” 

On account of its destructiveness to buildings in Europe it also goes 

under the German name “ Hausschwamm.” It rots cone timber 
for the most part. 

Coniophora puteana (Pl. VIII, figs. 5 and 6) resembles Merulius 
lachrymans in color and general habit of growth. It is less gelati- 
nous, however, and produces no porous strands. In some situations 
it produces a smooth, very thin, membranaceous layer on the surface 
of timber; at other times the surface is quite warted or convolute. 
The danger from the fungus is enhanced by its ability to rot hard- 
wood as well as coniferous timber. 


TIMBER STORAGE IN THE EASTERN AND SOUTHERN STATES. 385 


The fact that we are dealing here with two fungi which are known 
to be widely distributed in lumberyards in the United States, not only 
in the region covered by this study, but also along the Pacific coast, 
coupled with our knowledge of the rather common occurrence and 
seriousness of the same organisms in buildings throughout the same 
range, is a cause for grave concern on the part of both lumbermen 
and builders. 

Both fungi can readily be introduced into buildings by means of 
diseased lumber, and it is very probable that at least some of the 
outbreaks in compara- 
tively new buildings 
which have come to 
the attention of the 
writer can be attrib- 
uted to this source. — 

Besides Merulius 
lachrymans and Co- 
niophora cerebella the 
writer has twice en- 
countered another or- 
ganism of much the 
same habit of growth 
and _ destructiveness. 
This organism, the 
identity of which has 
not yet been deter- 
mined, was first found : 
in a retail lumberyard 
in Alabama and later 
in a cotton warehouse [2a , 
in Mississippi. The Poor 


Fic, 36.—The solid type of built-up plank foundation. 
owner of the lumber- This permits air circulation beneath the piles in only 


- one direction. The ends of the stock have been . 
painted to prevent checking. 


yard had appealed to 
the writer for assist- 
ance in eradicating a very serious infection, so a careful inspection 
was made at the first opportunity and the organism was found in 
great abundance in all three of the open storage sheds, where it had 
destroyed many of the foundation timbers and also passed upward 
into the stored lumber (PI. X, figs. 1-4). The first serious infection 
noted in this yard occurred six years ago, when two carloads of 6 by 6 
pine timbers piled in the open yard were so badly decayed to a height 
of 6 to 8 feet in the piles as to be rendered useless for building pur- 
poses. This material was at once disposed of for firewood. Three 
years later a further outbreak occurred in two of the open storage 
sheds and in an addition attached to the small office building. Dur- 
ing 1913 a serious infection was also found in a third open shed 


36 BULLETIN 510, U. S. DEPARTMENT OF AGRICULTURE. 


According to the owners, the immediate loss of this yard in stock 
and repairs up to October, 1914, was estimated to be between $1,000 
and $2,000. This represents, however, only the actual loss to the com- 
pany in lumber, figured at wholesale prices, and labor necessary in 
making repairs. The potential danger to the consumer using such 
stock, even though but very slightly infected, would amount to very 
much more than this sum, for a single stick introduced into each of 
a number of new buildings would occasion an incalculable amount of 
damage if such timbers happened to be placed in a moist situation 
favorable for the further development and spread of the fungus. 

As soon as the infec- 
tions were noted as seri- 


tempted eradication’ and 
control measures. In the 
office building the spread - 
of the fungus has been 
checked by proper ven- 
tilation, and in the sheds 
the same methods are be- 
ing applied by removing 
the cinder fills beneath. 
them and raising the 
foundations to a height’ 
of 18 to 24 inches, plac- 
ing the sills on brick 
piers. In future repairs 
the writer has suggested | 
the application of either 
mercuric chlorid or some 
creosote compound to the 
Fic, 87.—The latticed type of built-up plank founda- NeW timbers. 

tions. This is an improvement over the solid type, One member of the 

as it allows better ventilation beneath the piles. company 80 firmly be- 
lieved that the cinders used for filling about the yard had been 
highly favorable to the development and spread of the infection 
that orders were given to remove all of them from beneath the 
sheds. While it is possible that the infection may have been in- 
troduced by means of the cinders, the rapid growth of the fungus 
‘was mainly due to poor ventilation. Cinders have been used by a 
considerable number of other yards with complete satisfaction. 
Ashes, however, are not to be recommended. There are records in 
German literature where ashes used for filling between floors to 
deaden them have been the source of fungous outbreaks. The case 
of a cotton warehouse investigated by the writer, where pine flooring 


PIOOF 


ous, the company at- | 


TIMBER STORAGE IN THE EASTERN AND SOUTHERN STATES. 37 


laid on flat 2 by 6’s resting on ashes was very quickly rotted out by 
this same fungus (Pl. IX, figs. 3 and 4), likewise offers circum- 
stantial evidence. 
The remaining fungus which needs consideration is Peniophora 
gigantea (Fr.) Mass. (Pl. X, figs. 5 and 6). This is a white to 
pale creamy moldlike growth when immature. When mature it 
forms a waxy incrustation on the surface of the timber, closely ad- 
herent when fresh, but when dry tending to become hard and horny 
and to curl up at the free edges. This organism is widely distrib- 
uted, mainly on pine timber, throughout the southern pine belt, and 
also occurs on conifers in the Rocky Mountain region. In the South 
it is frequently found in the woods, whence it readily passes to 
stored lumber. Many lumberyards hee been abundantly infected 
_ with it ever since they 
started in business; so 
long, in fact, that to 
sever the attachment 
would be like losing 
an old acquaintance. 
From the southern 
yards it has been in- 
troduced northward 
and is very conspicu- 
ous at certain points 
along the North At- 
lantic coast (PI. ITI, 
fig. 7). The timber 
reaches these points 
mainly by boat. Close 
storage of the green or 
partially dried stock 
in the hold of a vessel 
‘during an ocean voy- 


PIOIF 


age of perhaps cceral Fic. 38.—Concrete foundations in the retail yard in 


Al a 
weeks usually permits abama shown in figure 15. 


a vigorous development of the fungus. As a result of this, infections 
are so abundant in some of the North Atlantic yards that one would 
have difficulty in finding any clean material whatever. _ 
It is fortunate that the organism does not approach in destructive- 
ness such forms as have been previously described, else many lumber- 
yards would be doomed immediately. It is a wood-destroying fun- 
gus, however, which limits its action to the sapwood. Although the 
deterioration is comparatively slow, it does weaken the timber to a 
considerable extent and should be puirded against along with the 
more dangerous fungi. 


/ 


38 BULLETIN 510, U. S. DEPARTMENT OF AGRICULTURE. 


WOOD PRESERVATIVES IN THE LUMBERYARD. 


Aside from the advisability of preserving permanent structures in 
the lumberyard by the use of antiseptics applied to or injected into 
the wood, the question of preserving the lumber itself from incipient 
infection until it reaches the consumer is one which merits careful 
thought. During the past decade the use of soda (sodium carbonate 
or bicarbonate) dips to prevent blue stain has become general 
throughout the southern pine belt. Within the writer’s own experi- 
ence, sawmill men who in 1909 scoffed at such a measure had within 
three or four years fallen in with the procession and were enthu- 
siastic advocates of it. As yet the idea of dipping the lumber to 
prevent infection from true wood-rotting fungi has not been con- 
sidered by the lumber- | 
men. The soda dip is — 


plish the desired end, 
so we must look else- 
where for a_ suitable 
preservative. Mercuric 
chlorid is a hazardous 
thing to use on general 
stock, on account of its 
extremely poisonous 
nature, but is very efli- 
cient and safe enough 
for special purposes. 
Zine chlorid is objec- 
tionable mainly on ac- 
rior ~=>s count of its capacity to 


Fic. 39.—Broken foundations, a result brought about 3 
by not reinforcing the concrete. The company later attract moisture. Of 


embedded some old 20-pound steel rails in the con- the remaining colorless 
crete near the top. 
salts in use for wood 
preservation sodium fluorid or some colorless salt of hydrofluoric 
acid would probably meet the needs of the situation very well. So- 
dium fluorid is highly toxic to fungi, but can be handled by workmen 
with no danger of poisoning. It is colorless, easily soluble, and can 
be handled in any way that the soda dip can. It is more effective 
than soda and so could readily be substituted for it, thus protecting 
against both the blue stain and the wood-rotting fungi by a single 
treatment. 
This whole feature of dipping lumber in, this way to keep it in 
a clean condition for the consumer must necessarily involve the 
close cooperation of millmen, wholesale men, and retailers. The 
millman may feel indifferent to the proposition, claiming that the de- 


not sufficient to accom- 


TIMBER STORAGE IN THE EASTERN AND SOUTHERN STATES. 39 


terioration in his yard is not sufficient to warrant it. But this is 
not merely a mill problem; it is a lumber problem which involves 
the entire industry and the cooperation of all its members. Even 
though the mill operator may not in many cases suffer personal 
monetary loss, still he is often a contributing factor in the losses 
borne by the retailer and consumer, for incipient decay originating 
in mill yards and passed over to retail yards may during the later 
period of storage progress rapidly. } 

The added cost of treatment would be insignificant in comparison 
with the benefit derived, and if the lumber trade would take the 
trouble to explain the benefits to the consumer the slight additional 
expense would in all 
probability readily be 
met by him. Even 
though it should not be 
deemed feasible to add 
the cost of treatment 
to the finished product, 
the direct saving ac- 
cruing to the lumber 
dealer himself should 
warrant the expense. 
It is imperative that 
something be done by 
the lumberman to put 
his product on a more 
favorable competing 
_ basis with other struc- 
tural materials if he is | 
to safeguard the lum- PLO 


b f f Fig. 40.—A southern retail. yard, showing a most in- 
ber business for the sanitary way of handling lumber. Structural timbers 


future. should never be thrown promiscuously about on the 
: ground in this manner to become infected with wood- 
Another line of en-  Gestroying fungi 


deavor which would © 

reflect favorably on the whole industry is for the lumber dealer to 
carry in stock, or at least be in a position to produce on order, 
timber thoroughly treated for construction purposes by certain of 
the well-known preservative processes. The wood-preserving in- 
dustry to-day is primarily conducted for the benefit of the heavy 
consumer. ‘The builder who may need only small quantities of 
treated stock to place where decay is most likely to occur in his 
structure is usually unable to obtain it except at prohibitive cost. 

_ The preservative treatment of timber is no magic process and in- 
volves no heavy expenditures for necessary apparatus, especially 
In connection with the simpler methods of treatment. The kyaniz- 


40 BULLETIN 510, U. S. DEPARTMENT OF AGRICULTURE. 


ing process consists merely in the immersion of the timber in an 
open wood or concrete tank containing a solution of mercuric chlorid. — 
Any of the other water-soluble salts could be applied in the same — 
way. Creosotes and carbolineums can also be applied in this manner. — 
While in many cases the amount of preservative which can be in- 
jected in this way would not be sufficient to fully protect timber in 
direct contact with the ground, in most cases where treatment is 
indicated in buildings it would be sufficient. Such treatments could 
be carried out by any one at any point, and the local treatment of 
timber would probably be cheaper than when done at a distant cen- 
tralized plant. In the East, such a local method of treatment is 
being carried out by at 
least two lumber dealers 
within the writer’s ac- 
quaintance. 

If treated timber were 
put on the local markets as 
a standardized product, as 
readily available to the 
man who needs 100 feet as _ 

-to him who uses it by the 
100,000 feet, the favorable 
results experienced by the 
public in the use of the 
treated product would in 
the course of a few years 
create a demand and be a 
stepping stone toward a 
more profitable lumber in- 
dustry. 


BRANDING STRUCTURAL 
TIMBER. 


PIO6F 


Fic. 41.—Wagon loaded with fragments of lumber Th = J 1 4 
to be hauled away. This is the highly com- ae discussion now leads — 


mendable practice by which one lumber company yg to a consideration of the 
keeps its yard clear of débris. 4 
advantages of branding 
timber in order to safeguard both the reputable timber producer 
and the consumer. Such a practice is of particular value in the 
case of dimension timbers where a standardized uniform product, 
graded particularly on strength and durability, must be supplied. It 
is customary at the present time to’so brand longleaf pine for export, 
but the ‘practice is very little followed for the interior trade. Some 
few retailers stencil their name or brand on certain stock, but this is 
with them more a matter of advertising than a guaranty of quality, 


TIMBER STORAGE IN THE EASTERN AND SOUTHERN STATES. 41 


and this must necessarily be the case until a standard and succinct 
set of grading rules is put into practice by all dealers. 

Branding not only puts the company’s guaranty of quality behind 
the product, but indicates as well the kind of timber supplied. Thus, 
for example, an operator in Douglas fir and western white pine in 
Idaho could not then possibly confuse his product with southern pine 
or eastern pine when it reaches the eastern market. For the architect 
it is very essential to know that the kind of timber he receives accords 
with the specifications. 

The biggest and most enduring reputations in any line of indus- 
trial activity are based on the best type of service. When the lum- 
berman who has the highest desire for good service throws his prod- 
uct: promiscuously on the market with the lower grade materials, he 
is at the same time throwing away an industrial asset of no doubtful 
value. This will become more and more the case as the building 
public wakes up to the dangers lurking in the use of inferior or 
fungus-infected timber. 

The timber of the United States is a national asset in which the 
citizens have a certain vested interest which calls for the best util- 
zation possible. The lumberman as guardian of these interests cer- 
tainly owes to the public no less than his’best efforts to convert the 
forest into a finished product which shall ultimately reach the con- » 
sumer in prime condition. 


CONCLUSIONS. 


Improvement of lumber storage conditions can be brought about 
by modifying present insanitary practices along the following lines: 


(1) Strong efforts should be made to store the product on well-drained 
ground, removed from the possible dangers of floods, high tides, and standing 
water. 

(2) All rotting débris scattered about yards should be collected and burned, 
no matter whether it be decayed foundation and tramway timbers or stored 
lumber which has become infected. In the case of yards already filled in to 
considerable depths with sawdust and other woody débris the situation can be 
improved by a heavy surfacing with soil, slag, or similar material. 

- (3) More attention should be given to the foundations of lumber piles in order 

to insure freedom from decay and better ventilation beneath the stacks. In 
humid regions the stock should not be piled less than 18 to 24 inches from 
the ground. Wood blocking used in direct contact with wet ground should be 
protected by the application of creosote or other antiseptic oils or else re- 
placed by concrete, brick, or other durable materials. Treated horizontal skid 
timbers would also be highly advantageous, for stock should never be piled 
in. direct contact with diseased timber. 

(4) Instead of throwing the “stickers” about on the ground, to become 
infected, they should be handled carefully and when not in use piled on sound 

foundations and kept dry as far as possible. If resinous pine or the heartwood 
_ of such durable species as white oak or red gum be employed, the danger of 
possible infection will be greatly decreased. 


4Y BULLETIN 510, U. 8. DEPARTMENT OF AGRICULTURE. 


(5) In most regions lumber should not be close piled in the open, but should 
be “stuck” with crossers at least 1 inch thick. Lateral spacing is also very 
desirable. Roofing the piles should not be neglected. 

(6) In storage sheds the necessity for piling higher from the ground is very 
apparent in many cases. The same remedies apply here as for pile foundations 
in the open. The sheds should be tightly roofed and the siding should not be 
run down below the bottom of the foundation sills. Free air circulation should — 
be allowed from all sides beneath the inclosure. Only thoroughly dry stock 
should be stored in close piles under cover. 

(7) Should fungous outbreaks occur in storage sheds not constructed to meet 
sanitary needs the infected foundation timbers should all be torn out and 
replaced with wood soaked in an antiseptic solution or by concrete or brick. 
In all cases the new foundations should be so constructed as to keep the lumber 
well off the ground, and the soil and timber immediately adjoining the infected 
area should be sprayed or painted with an antiseptic solution of a water-soluble 
salt, like sodium fluorid, mercuric chlorid, zinc chlorid, or copper sulphate. 

Stock which has become infected should never be sold for permanent con- 
struction purposes. The placing of such infected stock in buildings may lead 
to disastrous results, for which the dealer may be held responsible. 

(8) The dipping of yard stock in a water solution of sodium fluorid appears 
advisable from the standpoint of preventing blue stain and incipient infection 
with wood-destroying fungi during storage. 


PUBLICATIONS OF U. 8S. DEPARTMENT OF AGRICULTURE RELAT- 
ING TO TIMBER STORAGE CONDITIONS, ETC. 


AVAILABLE FOR FREE DISTRIBUTION. 


Cottonwood in the Mississippi Valley. (Department Bulletin 24.) 

The Southern Cypress. (Department Bulletin 272.) 

Measuring and Marketing Woodlot Products. (Farmers’ Bulletin 715.) 

The Preservative Treatment of Farm Timbers. (Farmers’ Bulletin 744.) 
Preservation of Piling Against Marine Wood Borers. (Forestry Circular 128.) 


FOR SALE BY THE SUPERINTENDENT OF DOCUMENTS, GOVERNMENT PRINTING 
OFFICE, WASHINGTON, D. C. 


Uses for Chestnut Timber Killed by the Bark Disease. (Farmers’ Bulletin 
582.) Price, 5 cents. 

Rocky Mountain Mine Timbers. (Department Bulletin 77.) Price, 5 cents. 

The Toxicity to Fungi of Various Oils and Salts, Particularly Those Used in 
Wood Preservation. (Department Bulletin 227.) Price, 10 cents. 

Forest Pathology in Forest Regulation. (Department Bulletin 275.) Price, 
10 cents. 

Wood Preservation in the United States. (Forestry Bulletin 78.) Price, 
10 cents. 

Preservative Treatment of Poles. (Forestry Bulletin 84.) Price; 15 cents. 

The Preservation of Mine Timbers. (Forestry Bulletin 107.) Price, 10 cents. 

Experiments on the Strength of Treated 'Fimber. (Forestry Circular 39.) 
Price, 5 cents. 

The Preservative Treatment of Loblolly Pine Cross-Arms. (Forestry Circular 
151.) Price, 5 cents. 

The Prevention of Sap Stain in Lumber. (Forestry Circular 192.) Price, 
5 cents. : ; 

The Absorption of Creosote by the Cell Walls of Wood. (Forestry Circular 
200,) Price, 5 cents. 


43 


v 
. wy 
“4 ‘ 
' 
~ ¥ tv 
Pre: oe mae 
7 + 
: - 
7 <3 
7 
s 
‘ 
: a 
Pwr bak - po) - 
airy =e ie eee X 
7 ie! my Terie “4 
. 
> he a eS 4 
aipaie 2 
‘ iy ¥ 4h See 
af 
t be by é ha A \ 
sed fe 
‘ ., \ Site 
‘ o “Ed 
<2. Pee 


ADDITIONAL COPIES 

OF THIS PUBLICATION MAY BE PROCURED FROM 
THE SUPERINTENDENT OF DOCUMENTS ~ 

GOVERNMENT PRINTING OFFICE 
WASHINGTON, D.C. 

AT ites se 

20 CENTS PER COPY 


; i Vite Se 


? 
« - 2 5 
. 
r 
‘ 
‘ 
~ 
' 
4 
! 
t 
t 
‘ 
1 d 
ay 
oe 
: f 7F 
. f 
i ‘ 
t i 
4 ~ 
' 

3 bs te 

. - . 


te 


op), 


?- 


a 


* 
A, p: I 
# | 
C 
‘ 
- 
& 
' * 
- 
‘ 
‘ 
. , 
ee 
4 
* > 
* 


ache Pian . 
feng! TP chy ees 


2 tn 
ae oe Tt 


# 
+ 


‘ 
* 


UNITED STATES DEPARTMENT OF AGRICULTURE 


Contribution from the Bureau of Plant Industry 
WM. A. TAYLOR, Chief 


"Washington, D. C. PROFESSIONAL PAPER June 12, 1918 


FOREST DISEASE SURVEYS. 


By James R. Wetr, Forest Pathologist, and Ernest E. Husert, Scientific Assist- 
ant, Office of Investigations in Forest Pathology, Bureau of Plant Industry, 
Missoula, Mont. 


CONTENTS. 
: Page. Page. 
Impecugnme ss 1. |. Pathological intaps.6. uo 27 oe ae 19 
Object of forest disease surveys__-- 2 |, UTE TMs ae eee 2 Sn ee et 23 
- Disease-survey methods —__---.--~-- 13 
INTRODUCTION. 


The National Forests are administered with the expectation of 
their becoming self-supporting through the medium of returns from 
such activities as timber sales, grazing, and special-use privileges. 
Of these operations, that of the sale of timber is, in the National 
Forests of the northwestern United States, unquestionably of the 
greatest importance in respect to paying the expense of administer- 
ing the forest. In district No. 1 in the year 1916 the total receipts 
from timber sales equaled $439,880 and grazing $50,836. These figures 
show the relation between the two incomes derived from the princi- 
pal forest activities of this district. Some few of the forests have al- 
ready attained a position of self-support. One forest in particular 
is reported to have outdone all expectations and in so doing has aided 
in the administration of forests whose incomes have been less than 
their expenses. In such self-supporting forests it is always found 
that a ready market and available timber supply have resulted in a 
maximum of timber sales. It is, then, a foregone conclusion that 
timber sales in the National Forests of the Northwest are the main- 
stay of a self-supporting policy and that all data of value to timber- 
sale operations are bound to be of value in their successful super- 
vision. The data and recommendations included in this paper are 
based on conditions prevalent in district No. 1 of the United States 
Forest Service. 

39732°—Bull. 658—18——1 


2 BULLETIN 658, U. S. DEPARTMENT OF AGRICULTURE. 
OBJECT OF FOREST DISEASE SURVEYS. 


Timber surveys have as their prime object the gathering of such 
data upon proposed sales areas as will be of use in the appraisal and 


Po PS ee 


administration of the sales, and it is this survey which makes the — 


sale possible. The collection of valuable data on the board-feet con- 


pet 

Sea a 
LPYEO = la, ain, 

oS 


\ 
t 
‘ 


Fic. 1.—Pathological map of sections 22, 23, 24, 25, 26, and 27, T. 2 N., R. 15 W., 
the Big Hole area, based upon the map of the timber survey of that area in > 
the Deerlodge National Forest, Mont., showing timbered areas infected with disease. 
The rot percentages are indicated for heart-rot (Trametes pini (Brot.) Fr.) and 
butt-rot (Polyporus schweinitzii Fr.) only. Crosshatching indicates infection areas. 
Other symbols on the map are part of the Forest Service map legend, such as Spr. 
200, which indicates Engelmann spruce, 200-year age class; L. P. 60, 0.7 equals 
lodgepole pine 60-year age class, density 0.7; Gr. equals grassland; Br. equals brush. 
A, Pine rust (Cronartium coleosporioides (D. and H.) Arthur), gall and blister 
forms, on lodgepole pine (Pinus contorta) ; B, smelter-smoke injury, principally of 
alpine fir (Abies lasiocarpa) and Douglas fir (Pseudotsuga tavifolia) ; C, honeycomb . 
rot (Trametes pini (Brot.) Fr.), principally on Engelmann spruce (Picea engel- 

_manni); D, porcupine injury—peeling of bark and girdling of lodgepole pine; 
E, cubical butt-rot (Polyporus schweinitzii Fr.) on lodgepole pine and white-bark 
pine (Pinus albicaulis) ; F, mistletoe (Razoumofskya americana (Nutt.) Kuntze) 
on lodgepole pine. : : 


tents of the stand, cull percentages, forest types, age classes, topog- 
raphy, and logging factors is followed by an accurate map portray- 
ing the topography, types, density, age classes, and timber estimates. 


A careful stumpage appraisal of the area based upon these available — 
data and upon the various economic and topographic factors forms — 


the final step before contracts are let. 7 e; 


a. | ee 


FOREST DISEASE SURVEYS. 1 3 


In most cases the appraisal of a timber-sale area is based somewhat 
low in respect'to the total feet board measure of sound material, 
principally on account of the unknown amount of defect or rot to be 
encountered and sometimes partially for other causes, foremost of 
which is the desire to prevent overestimation. 

In timber surveys the estimating of timber is performed by mem- 
bers of the party who have been trained to estimate stands of varying 
mixtures, age, and soundness and who are thoroughly capable of 


Fic. 2.—Fruiting bodies of Trametes pini on lodgepole pine. Notice the swell- 
ing of the trunk where the fruiting bodies are attached. (Photographed by 
G. G. Hedgcock.) 


judging the board-feet contents of trees within reasonable limits of 
error. The addition to the party of an expert cruiser has been 
made as a means of aiding the estimators in this work and checking 
their results. The determination of the correct cull percentage due 
to rot is the aim of this arrangement in the crew. 

In certain types and ages of stand the-estimate may come close to 
the true scale, but, again, too small a percentage is deducted for cull 
due to rot, and consequently the estimate runs too high. A. sale con- 
tractor figuring possibly on a conservative margin and accepting the 


4 -BULLETIN 658, U. S. DEPARTMENT OF AGRICULTURE. - 


estimate at its face value may find upon cutting the stand that a great 
deal more rot is encountered than was expected. This fact alone 
could easily result in the logging operation turning out a loss instead 
of a profit, especially if the logging chance is not a favorable one. 
Such failures doubtless do not encourage the undertaking of further 
contracts, and fewer timber sales are the result. This has its ultimate 
effect upon the forest as a whole in an economic way. 

Recent studies made of the rots occurring? in forest trees have 
given information concerning the amount of decay prevalent 1 in: dif- 
ferent age classes and in different sites for a particular species of tree. 
These studies have indicated that the decay in a tree or a stand 
varies with such factors as age of stand, site, density, injuries, and 
moisture relations. Such being the case, a disease survey of the sales 
areas made either as a separate pathological survey or in conjunc- 


H1g..3.— Typical rot of Trametes pini (honeycomb rot) in white eae 


tion with the usual timber surveys would prove of 1 immense value in a 
closer estimate of the sound board-feet contents of the stands. A 
disease survey in conjunction with the timber-survey work would no 
doubt be the more feasible plan of the two, since it would require 
no additional men for the crews and should not appreciably affect 
the cost per acre. All that would be required in order to secure the 
disease data in more accurate form is the training of one of 
the members of each unit crew in the proper methods by which the 
‘various pathological determinations are made. This would mean the 
‘ability to judge more accurately the cull percentage due to rot and 
the ability to recognize all the outward indications of decay as well 
as the principal fungi attacking forest trees. ‘Preferably, the esti- 
mator should be the one selected to assume this duty, as it is his indi- 
vidual work which determines the total estimate and the eull percent- 
age of the stand. ' ! 


t geineeke, E. P. ‘Forest pathology in ‘forest regulation. D. S. Dept. Agr. Bul. 275, 
62 p. 1916. 


FOREST DISEASE SURVEYS. 5 


The topographer, while sketching in the type lines and indicating 
the age class divisions, can at the same time indicate the boundaries 


Fig. 4.—Typical rot of the Indian-paint fungus on Abies grandis. Note the spines on 
the fruiting body of the fungus. (Photographed by G. G. Hedgcock.) 


of the heavier disease infections and also pencil in the cull percent- 
ages. In this way a pathological map? can be secured for the area 


1 Weir, J. R. Some suggestions on the control of mistletoe in the National Forests of 
the Northwest. In Forestry Quart., v. 14, no. 4, p. 567-577. 1916. 


6 BULLETIN 658, U. S. DEPARTMENT OF AGRICULTURE. ‘ 


~ 


surveyed, and along with careful notes of the estimator upon the 
diseased areas and upon data secured by means of a few small sample 


plats a very close 
estimate of the cull 
percentage to be ex- 
pected can be had. 
Checks can be made — 
upon the estimator’s 
work by the expert 
cruiser. Members 
of the Office of In- 
vestigations in For- 
est Pathology can 
render excellent 
service by aiding 
each unit crew in 
the field in becom- 
ing familiar with 
the various diseases 
and their causes. 

If properly ad- 
Fic. 6.—Typical rot of the velvet-top fungus in the end of a justed, this work 

white-pine log. Note the cubical character of the rot. would cause no va- 


riations in the amount of line run per day by the unit crews. The junior 


FOREST DISEASE SURVEYS. sf 


writer has tested and proved this assertion in practice while employed 
by the Forest Service on the Big Hole timber survey made in 1914 
in the Deerlodge Na- 
tional Forest of 
Montana. From the 
data thus collected 
pathological maps 
were made, giving 
in colors the areas 
of the stand in- 
fected, respectively, 
with the pine rust 
(Cronartium coleo- 
sporioides (D. and 
H.) Arthur), both 
gall and blister 
po. mistletoe Fic. 7.—Fomes pinicol h d-belt F i 

( WG SL fs ke ya a ale pinico ae e a belt Fomes growing on 
americana (Nutt.) 

Kuntze), heart-rots (Trametes pini (Brot.) Fr. and Polyporus 
‘schweimiteu Fr.), and various other diseases (fig. 1). Careful notes 


Yi3W ] 
li ad 


SAS 3 
ener 


> 
PLLELS 


devs | 


.~ 
= 


a 
ie 
7s 
ee 
Ae 5 
Ll 
. a 

3 


Fic. 8.—Typical rot of the red-belt Fomes in grand fir; cross and tangential sections. 
Note the strands of white felty masses (mycelium) throughout the rotted areas. 


were taken as to the percentage of infection in each case, and a closer 
estimate of the amount of cull was made possible. In one particular 


8 BULLETIN 658, U. S. DEPARTMENT OF AGRICULTURE. 


case an estimator wished to give a full estimate of a stand of white- 
bark pine (Pénus albicaulis Engelm.) growing upon a flat ridge. The 
trees of this stand upon closer examination were found to be almost 
universally heart-rotted with Polyporus schweinitzii for a distance of 
5 to 12 feet up from the base. The trees were fairly large and if 
sound would have made excellent stull material, the chief product 
in the Big Hole Basin region of Montana. Giving a full estimate to 
these trees would have meant a serious overestimation of the stand, 
since it was finally estimated that about 40 to 50 per cent by volume 
was cull due to the heart-rot. Fruiting bodies of the causal fungus 
almost hidden in. the dé- 
bris at the base of the 
trees gave the determin- 
ing clue, and soundings 
upon the trunk followed 
by notching completed the 
determination. 

There has always been 
a serious need for some 
method by which a fairly 
accurate estimate can be 
made of the rate of decay 
of a stand of timber. 

Good results as to the 
probable cull percentage 
to be expected from rot 
upon a certain stand have 
been secured by expert and 
experienced cruisers and 
appraisers. Timber sur- 
veys have in most cases 
placed the estimates of 
Fig. 9.—Polyporus sulphureus, sulphur fungus, at sound timber within a rea- 

base of larch. sonable limit of error; but 
evidently no attempt has ever been made to secure a more accurate 
result in respect to the cull in a stand due to rot other than those 
results secured by ocular estimates. Occasionally in the administra- 
tion of National Forests the question arises concerning the probable 
rate of increase in rot per annum in a certain stand of timber. The 
resultant decision as to the time of disposal of the timber hanging 
in the balance depends upon the amount of accurate knowledge and 
the data at hand regarding the decay in the trees. If proper and 
sufficient data are secured, these will furnish the total volume and 
the total volume of rot for the stand in question. With these as a 


FOREST DISEASE SURVEYS. 9 


basis and figuring in all the economic and silvicultural factors con- 
cerned, a cutting age can be computed, aimed to secure the greatest 
amount of sound material at a minimum of cost. No definite rule 
ean be given as to the value of the ratio between the total volume and 
the volume of rot required in determining the cutting age. Too 
many factors are concerned even to generalize, and each stand must 
be judged according to the conditions present at the time it is under 
consideration. But it is unquestionably true that data giving the 
relation between the sound and the decay increment in a stand, as 
well as giving an approximation of the rate of increase in decay to 
be expected, will aid 
greatly in solving the 
question of the proper 
cutting age for that 
stand. 

Forest management 
of .this kind can be 
practiced to a profitable 
end provided intensive 
methods are employed 
in making a _ special 
disease survey of the 
area in question. Sure- 
ly this would be a step 
toward more intensive 
and more economic for- 
est management and 
would aid in solving 
many of the perplexing 
problems hinging upon 
the decay in_ timber. ' if Ay 
The cost of such a sur- JU ety 

etricsystem@} | ae 
vey would not be pro- EL | 
hibitive by any means, Fig. 10.—Typical rot of the sulphur fungus in larch. 
even in case the stand | 
were composed of more than one age class, since sample plats of 
small dimensions could be successfully used in securing the necessary 
data upon the decay. To supplement these and aid in the diagnosis 
of the stand, such available data previously secured for similar tree 
species, age classes, sites, etc., could be used to advantage. 

Aside from the advantage secured in arriving at a more accurate 
rot percentage for a stand, a disease survey accompanied by a patho- 
logical map would be extremely useful after the sales are closed, the 
brush burned, and preparations made for the reforestation of the 
cut-over area. Looking into the future is the forester’s basic prin- 

39732°—1S—Bull. 658——2 


10 BULLETIN 608, U. S. DEPARTMENT OF AGRICULTURE. 


ciple, and whenever forestation of an area either by natural or arti- 
ficial reproduction is contemplated it would be extremely unwise to 
overlook the risks to the young growth incurred by possible disease. 
A pathological map would serve to give the previous location of dis- 
easecl trees, as well as the location of diseased uncut areas surround- 
ing the sale area and the localities and sites where diseases seem most 
prevalent, and would also serve to indicate’ whether the seed trees 
left, if any, were of a group which was heavily diseased or not. Dis- 
eased trees of any kind left as seed trees or otherwise on or surround- 
ing a cut-over area always act as distributing points of disease to the 
| young growth occupy- 
ing the near-by areas. 
For this reason atten- 
tion has recently been 
centered upon the in- | 
troduction and strict 
enforcement of sanita- 
tion clauses in all tim- 
ber-sale, . operations.t 
These clauses include 
the removal by burn- 
ing of all heavily in-: 
fected standing trees 
and all cull material 
left on the area and 
strongly advise the use 
of healthy trees as seed 
trees instead of dis- 
eased ones. 

For the same reason 
as given above for the 
protection of young 
growth in cut-over 
areas, a disease survey 
is even more necessary 
upon proposed nursery sites, present nursery sites, and all plantation 
sites. Wherever young trees are grown in close proximity to heavily 
diseased native trees or alternate hosts of forest-tree rusts there 


Fic. 11.—Fomes officinalis, chalk fungus, on western larch. 


1 Meinecke, E. P. Forest-tree diseases common in California and Nevada. U. §S. For- 
est Service Manual, p. 62. Washington, D. C. 1914. 

Weir, J. R. Some factors governing the trend and practice of forest sanitation. Jn 
Iorestry Quart., v. 13, no. 4, p. 489. 1915. 

Meinecke, E. P. Forest pathology in forest regulation. U. S. Dept. Agr. Bul. 275, 
62-p: » 1916, : 

Weir, J. R. Larch mistletoe: Some’ economic considerations of its injurious effects. 
VU. 8. Dept. Agr. Bul. 37, p. 24. 196. 

Weir, J. R. Mistletoe injury to conifers in the Northwest. U. 8S. Dept. Agr. Bul. 360, 
p. 83-37. 1916. ; 


Olin em nara 


= 


i te) 


— 
- 


a eS I, ee ee ee Fs 


FOREST DISEASE SURVEYS. 11 


always remains a great danger of infection spreading to the young 
stock, with consequent loss. This has been shown in several recent 
cases where forest nurseries were located in close proximity to dis- 
eased trees and alternate hosts. At the forest nursery at Haugan, 


Fic. 12.—Fomes officinalis, chalk fungus, showing typical rot in lodgepole pine. Note the 
white mycelium in the cracks. (Photographed by G. G. Hedgcock.) 


Mont., yellow-pine seedlings became seriously infected with Cronar- 
tium coleosporioides (Peridermium filamentosum Pk.). The disease 
was transmitted by means of the alternate form of the rust occurring 
on the Indian paintbrush (Castilleja miniata Dougl.), which was 
found growing at the very edge of the nursery beds.1. A survey of 


1 Weir, J. R., and Hubert, E. E. A serious disease in forest nurseries caused by Peri- 
dermium filamentosum. Jn Jour. Agr. Research, v. 5, no. 17, p. 781-785. 1916. 


12 BULLETIN 658, U. S. DEPARTMENT OF AGRICULTURE. 


the site, made at the time the nursery was contemplated, would no 
doubt have resulted in the discovery of the same rust upon the near- 
by lodgepole pines as well as upon the Indian paintbrush plants, and 
future losses would have been prevented. The infection with a 
needle fungus* of Douglas fir seedings at the Boulder nursery, Boul- 
der, Mont., and the occurrence of a mistletoe upon the seedlings? 
were due o these diseases being extremely prevalent upon the sur- 
rounding native trees of this species. The young and crowded seed- 
lings became ready hosts for the fungus, and considerable damage 
pecaitees 


Fig. 138.—Poria weirii, brown-cedar poria. Fruiting surface. 


In the State nursery at Roscommon, Mich.,’ a similar proximity 
of native infected trees and susceptible nursery stock resulted in a 
serious epidemic. 

No less care should be taken with proposed plantation sites upon 
burned-over or cut-over areas. A disease survey should be made 


1 Weir, J. R. A needle blight of the Douglas fir. In Jour. Agr, Research, y. 10, no. 2, 
p. 99-1038, 3 figs: 1917. J 

2 Weir, J. R. Mistletoe injury to conifers in the Northwest.. U. S. Dept. Agr. Bul. 
300.—pysoos LOG: 

3’ Kaufman, C. H., and Mains, E. B. An epidemic of Cronartium comptoniae at the 
Roscommon State Nurseries. In 17th Ann. Rpt. Mich. Acad. Sci., 1915, p, 188-189. 1916. 


Ls 


FOREST DISEASE SURVEYS. 13 


upon all such areas in which the newly transplanted seedlings are 
subject to infection by fungi or mistletoe. Many of the plantaticn 
sites of this region are located upon burned-over areas, and the 
majority of these are so badly fire swept that very little has been 
left in the form of coniferous hosts for forest-tree diseases. How- 
ever, to review the succession of plant hfe on a burned-over area, 
after a fire which has been sufficiently intense to destroy every vestige 
of humus and litter, is to find that the alternative hosts of some viru- 


\ 
Wic. 14.—Typical rot of brown-cedar poria in butt and roots of cedar. Note 
the laminations of the rot and (on the left) the fruiting of the fungus. 


lent needle or twig diseases have invariably appeared. In many cases 
the new plant succession carries with it alternate host plants of im- 
portant forest-tree rusts which soon bear their parasitic fungi, and 
some of these are found to menace the young tree growth upon the 
area. A disease survey of such a site is very necessary, especially 
if the site is to be used as a plantation area for susceptible seedlings. 


DISEASE-SURVEY METHODS. 


The most practicable methods only are to be applied by unit 
crews in gathering forest-disease data. These methods should be ap- 
plied with a reasonable knowledge of the principal destructive disease. 


14 BULLETIN 658, U. S. DEPARTMENT OF AGRICULTURE. 


agencies, such as fungi, mistletoes, smoke, frost, wind, and snow 
injury, their outward recognition, and their possible and actual dam- 
age to the trees. Sample plats of small dimensions can often be 
resorted to in order to ascertain the extent of a heart-rot in a certain 
age class. Borings can be made with an increment borer on a few 
sample trees and thus the kind of rot and in the case of butt rots 
the extent of decay can be determined. Soundings on the trunk, 
the presence of sporophores, the number of dead branches or in- 


HUD 
ni tac Osestem & : “al Sat a : 


I'ig. 15.—Fomes annosus, root Fomes. Typical fruiting bodies. 


juries, and the presence of the unmistakable swells and pitch flows 
occurring at old branch whorls all aid in the determination of the 
presence and extent of decay within a tree. The amount of decay 
bears a certain relation to the age of a stand, becoming greater as 
the stand grows older. 

Owing to this fact, a table similar to the cull table given on page 
25 of the Reconnaissance Manual of District 1, United States Forest 
Service, but giving the rot percentage only nee a range of age classes 
for each tree species would prove of value in judging the decay in 
the stand. Such a table would give a range in rot percentages to be 


FOREST DISEASE “SURVEYS. 15 


found in a certain age class, a certain site (slope and bottom) for a 
given tree species for 
a given kind of rot, 
and would be com- 
piled from intensive 
field studies made 
upon felled trees. It 
would properly be 
termed a “table of 
rot percentages ” and 
would be used by 
the estimator of each 
unit crew to deter- 
mine the rot percent- 
ages for each type of 
- forest encountered. 
Further deductions 
for other defects 
could then be esti- 
- mated and the total 
cull percentage etl Fic. 16.—Typical rot of the root Fomes in grand fir. Note 
cured by the addition ‘the black dots in the white areas. 
_ of the rot. percent- , | 
® age. In conjunction 
; therewith, another 
_ table giving (1) the 
; class of defect, (2) 
~ common name of the 
defect, (3) the fun- 
gus causing it, (4) 
the various tree spe- 
cies affected, (5) the 
general external and 
internal characteris- 
tics of the defects, 
and (6) the average 
oxtent of the rots 
and the general form 
of the rot within the 
tree would be of 
great service to the . : eo 
estimator. Such a Fic. 17.—Pholiota adiposa, the scaly Pholiota. (After 
table prepared from | wae | 
field data secured during the past three seasons is here submitted. 
(Table I; figs. 2 to 28.) 


ee Cee 
ES) edie i eth 
3) 4 oe 


{ 


BULLETIN 608, U. S. DEPARTMENT OF AGRICULTURE. 


16 


*S0] Js1y puosoq 
Sutoueape jou Ajrensn Bol xs) paeadn 
991} 944 JO OsBq OY} WO |VOTUOD :401 BUTZI 
-uoqied ‘euTyuUedIMy Jo JOpo ‘(umNT,soA ur) 
[BI19{VUL OYT[9[9} OJITA JO S}sN.o SNOUISEL 
UIY} YIM AT[VUOTsBO00 ‘AIP Woy 9[}}TI 
pue ‘A;quimio ‘jeorqno ATpeounouos 
‘UMOIG YsIpper ‘e8eqys peoIddA, SuMOIG 
YSIppel4ysi ‘sosejs A[1V9 UT: (S}OO1 S199 


Os[®) 901} JO 44nq Jo 4or-y1e0q ULIO;TUGQ 


“poomMy.IBey OY} JO [[e 10 
ysour SsurAdnooo Ur us0jyTun AuoA ‘ABOOp 
4S9}O18 JO VaIe 94} WOIJ SUOTIOeITp 440q 
UI [BOTUOD {Avoop poel0;00-yIep SUIONp 
-01d ‘asojn{[eo Sutonped ‘z1A “401 SutzTU0q 
-IVD $poeqjOL MOT[OY WoO ‘sUOTIeIO[OOSTP 
UMO1q YSIPped AIM ‘ASuTIY4s pus ‘Uayo1q 
“poqqid ‘( WOT}DeSSs0.10) BORJINS POMS :10[00 
per-Aysni daep @ Surmoys syouy ‘10;00 ut 
pot Aysni 04 ysTUMOI ‘AZUTIYS “470s ‘a3eIs 
jeordAy ‘poutejs Morjek ‘ASuods poom 


* ‘soseqs Arve Ut {(ATaI1{UO YsoUr[e SoToeds 
901} UBALS 0} PeUyUOdD) 4OI-jIvEYy ULIOJUQ 


*poom 
-LIvey ey} SuDpoe{ye ATULIOJIUN 40U sBole 
Ayoyed se uaqjo ‘sy aeddn 4e Sursede} 
‘[eoTuod ‘401-443Nnq sv fyuNIy UL ABoep 4so 
-{8913 JO VAI OY} WIOIJ SUOTIOOITP 440 UT 
[BOTUOD °401-99TYM SesSO[N[[IO 07 POOM ZUT 
-J19AUOD ‘ZTA “401 SULAJTUSTOp ‘poeyeiedes 
ssUlI jenuUs ‘poVos SULI sesvis poouvA 
-pe Ul pues sevore poqyid yyIM po[surat 


seyoyed ojmyM [[eUIs ‘UOTJD0s ssoJo Ut. 


‘(P910]OdSIp ) UMOIG ‘4jOs ‘AyuNd ‘sayoyed 
yeondyje oy ese, JO [VWs YUM 
‘U0T}09s JTS UT IO[OO YSTppe ‘seseys Ay Ivo 
UI ‘UIsoL OU JO 97441] JO Sool} UT 4O1-des 


JO 40J-J1VOY ‘S903 SNOUIseL UI 4OJ-]1V0]T 


‘ABOOP JO SOLSTICJOVICYO 


"40.1 [eord.44 Jo souesoid 
:$}00I pesodxe uo pue 991) 94} 
jo uoljzJ0d jeseq oy} UO ssurpunos 
‘$3001 posodxe oy} UI 4OI-UMOIG 
JO SUOT]BoIpUT {(yUNIy Oy) HO dn 
Ysty JOA9U) 901} OY} JO oseq 944 4B 
solnfur wmo1y Sumsst snsuny 4e 
-Yoviq SB puNnOojJsouTjeuIOS ‘(STIqep 
Aq peseaoo Apjred skemye A[Ieou) *)) pue 
0911 OY} Iveu puNnois oy} UO sns “ay ‘so ‘aa “at 
“uny ey} Jo sorpoq surmuay peorddy, |“daM ‘dd T ‘dA ‘dM 
"40.1 [VOTdA4 JO 9oUesaId 
‘079 ‘seze[q ‘sIvos o1y ‘ses SUIS 
-s0] SB yous ‘solmfat Auew {yunIy 
94} UO Opvul ssUTpUNOS ‘sqnys 
Yyouevlq P[O UL 10[00 pes-Aysni deep 
‘S[IOUM 9B SsUT[[eMs PoouUNouOId 
Aq porueduioose ‘sqnjs youriq 
peep jo 1equinu es1e{ :yo peddoip 
oe. seIpoq Sumy yeyy ‘s}ouy 
yund poi-Ajsni deep Aq 10 s8ut 
-[[9Ms Aq IOYITO ‘soy Lee 
y@ suoTyeoIpuT ‘9013 ey} UO s “HW 
“UNY oY} JO seTpoq suTyINIy ywordAy, | pue ‘HM ‘GD ‘AV 


“ULIOF 401-39Nq 
OY} PONPUT osBq OY} 7B S90BJ7BO $401 
[eo1d44 Jo gouesold ‘spuly snorea 
jo sormn(ur Aueur ‘Avoop SUTYOIpPUT 
‘ssouTyund 10 ssouMmoyTjoy 4097ep 04 
yUnI} oy} WO epeur ssUTpPUNOs ‘yo 
poddoip savy sorpoq surymay yey 
‘gouejsqns AyUNd yYsTUMOIq Aq "TT pue 
IO sj[aMs Aq IoyA1O ‘spIOWM YouRrG “Ta “Or {WD sary 
plo 78 suOT}VOIPUT :901} OY} UO | ‘HW ‘HM ‘Sa ‘dT 
snguny oy} JO solpog Surymaypeorddy, |‘daM ‘dd'Il‘'dA ‘dM 


‘peyoeyye 


‘qoojep 10 Avoep Jo susIs [VUIO} xX] Aypesoue see, 


‘(¢ ‘3y) sn3 
-uny doj-yoaloa ‘11z 
-JIUIeMYOS snsodAjo gy 


"(F 
*39) snsuny 4ured 
-uUeIpuy ‘wnt0}4 


' “(9 


(F 


-oul} UINTUOpouTYyoY |-3y) JoI-uMoIq AsUTYg 


*(g °30) snsuny 9yevos 


-sull ‘turd sojoureiy, 


phe 
*3Y) “401 quriooAguoyy 


“dn yo0j 
9 04 ¢ Ajyensn {(1e, 
“Noto “u1oyTUN) 8O[ 
4sIy 04UT 409} ZT 09 dn 
“$joOL WoOly ‘yor-49ng 


*901} 0119U9 {(IeNdITO 
‘uuiojtun)  4O1-yULIy, 


‘Ayoved Al[e1oues :401 
-430q sB suTyoR AIR 
-UOISB000 = ‘40.1-YUNTY, 


*(sommeu 
UOUWIUIOD pus OUT} 
-UdTDS) oyIsvied [esned 


"409Jep Ot} 
Joy oulvu WOUIUIORD 


-409]ap JO ssvIO 


: [-ourd moyjod Ul0jsom = X ‘ould 971YM UW19}sSOM =I M ‘yooTUIOY W10}SsoM =F] M ‘ould yieq-eqTYyM = Tg M ‘Yooyurey, UTeyUNOUI 
=HN ‘ourd ojodespoj=q qq ‘eurd 1equiy=q’{ ‘yore, U10}soM ="] ‘IY PULIZ=yH ‘oonids uuBUjesug =o ‘I svjsuog = qq ‘1vpeo Pol UlejsoM =_ ‘IY ouldje=q Vv ssuOTVIAVIEGG Vy] 


‘suaoifo Burysou pun ssojounjsa fo asn ay} sof saau, burpunjs sof suoyourwsajap fivoag— | A'TAV J, 


ke 


FOREST DISEASE SURVEYS. 


‘pooMIvoY UT PeoTMOS {401 SUIzZTUOGIvO ‘peijo1 MOT[OY SuTMIODN ATTeuy ‘ssuII yenuUE ZUTYeIedo9s pu soseis ysl UI dN SUTYvoIq puUv UTeIs 9Y} SsOlo’ SuTUUNI sosseur A4] 9] oytyM JO 


UB} JUST 04 YSLMoTpod ‘sYVor4s YSIUMOIG ‘10[00 AouUOY IO MOTLOA ‘a8BYs [BOTdA} SUTeys MO][9A-74 RT] B 


4ou) poomM puUnNos jo svole Je]jeus Aq poyeredes svoie YsTITyA ‘9984S 


‘1os1ey seyoyed yey ‘seyoyed yeoiqno ueeM4o 
Ajiea Ul ‘soumMlar ysno1yy soueijUe SUITES 


‘soseys A[IvO UT ‘(WISI OU IO 919}, YILM $901} JO Appedroutsd) 101-1VEY UIOJIUL ¢- 


‘poomdes jo [{8 10 qed pue poomzreey sully ‘uOjTUN ‘[eoTUOD 1401 BULAJTUSI[Op ‘se[eos 
yreq repun (umyookur) sesseu Ayjoy ouy ‘ASuods Ayjeuy ‘poqyeredes ssulz jenuue ‘soseys Js Ul ‘Sele O4IM JO 19}U90 UT s}Op YouTq yyIM AT[euotseoo0o ‘(payyid A[yueuTMOId 


[Bord 44 ‘20[00 UT YSIPpo1 0} OV[T] WOT] SUIZUEI ‘sedvys ATIVE UT :44Nq JO 4OI-yIeoYy Pues 4OI-des ULIOJTU x 


*ULIOJIUN ‘[eoTUOd {401 SUIZIUOGIGO ‘snsuUNy doj-J9AT[OA 9} JO VSO} 0} PoreduIOD SB SHOUIsoIUOU PU 1OxOIy} 


wmnTeokur JO sLoAVT ONTIL[9] OTM ‘AIP UsyA 9}I1Iq pue ATquimso ‘peoiqno ‘UMOIq YsIPpor ‘odeVxS [eoIdAY ‘UMOIG ZYST 4OI ‘seseys 


Q S001} SUIAT[ UT 4OJ-jIvEy SB ZUTJOe A[[eUOISvo00 ‘10qUIT} UMOP pu ZUIpUeys peop UT AT[edrourid punoy ‘401-y1v9q ULIOJIUL 1 


*19ABT 
sunmiy 10 JeapMod MoT[94-e8URI0 SOTO 
-SIp [[LM s1eyUvO puUv SSsUT|[OMS UO YZIeQ 
jo suiddiyo 44s] & ‘Isn3ny 03 Av; sur 
-INp snonojdsuooul st ose4s SUTJMIy UO MA 


(e) 


(z) 


*uLIojTun ‘TeoTuo £401 
Zurzaoqseo fs1eAVe[ UsEeM40q UNIT ‘eoAur 
Aqjo} WMOIG ‘sose}s PooUvAPe UI SsuULI 
jenuue Zuyeiedes poom Zurids petvo 
-9P {10[OO MOT[OA-ZUST] °4O1-J1V0y ULIOJTUGQ 


*mLIojTUn ‘feoTUod {401 
ZuIzTUOgIeD ‘s}Jao UI sessveur [eIjeaoAUr 
Aqay Ug, yyw ‘A[quindo ‘Arp ‘919411q 
‘UMOIG YSIPPol Zep ‘e8e4s [VOId AY SUMOIG 
qysy ‘sesejs A[Iwe Ul ‘4O1-yre0y ULIO}IUQ 
. . “aqoyron 
‘[BOTMOD £401 ZUIZTUOG IO [UOTIOeS SSOID UT 
podeys 1e}3s ‘s}jo[o0 UI sesseur [eITeoAuT 
Aqey AOI? WIM ‘(TVorqno A;psounouoid 
jou) Aquino ‘AIp usyM 97}41Iq ‘UMOIG 
Ystpport yiep ‘eseys yeoiddy ‘umoiq 


qysy ‘sedeys Ajreo Ut *JO1-YBeq ULIOJTU 


(1) 


‘sleyqueo pue sjes wodn yueld 
90} Q[}STU JO gotesYe ‘soyouRIG Pus 
YUN} JO SIOYUVO 10 S9dRJ}BO :SsUT 
-[[9MS psounouold uo sesseut AIOp 
-mod ‘moyjjeA-esuel0 jo (ysnsny 
0} Avy jo syjuOWM ZULINp) sousSseIg 

: ‘soqoueiq 10 YUNIy oy 
UO SsUT]TOMS SNONoIdsuod ‘suI00I1q 
-SoojIM ‘ssIM} pus seyouel 
uodn sjuejd o0j0;3stur yeordAy, 
401 [eotd44 Jo soueseid ‘yun UO 
9peUl SsUIPUNOS £901} OY} UO sns 
un} ey} JO sefpog suTyInIy peordAy, 
"$1001 posod 
-xo UO puUv 991} OY} JO OSeq OT} 
4@ S8UIpUNOS ‘{s}001 10 9913 OY} JO 
9seq oY} 38 MOT User ‘dn poiea00 
Ajjensn ‘saqo4010 4001 oy} UI sn3 
-UNJ 9} JO soIpog suTymMAy peordA J, 
‘sands 4001 pesodx¢6 UO pus 9913 84} 
JO 9seq oY} 78 SsUIPUNOsS ‘(sseur 
Ayund €& OJUT sj001 oY} yNOQGe 
SLIQ9P 4S910J OY} SUIZUEUIGD 194jO 
$91[0}010 4001 9} U1) 99.11 94 WO sns 
“UN 9y} JO sefpoq ZuTmMy jeordAy, 

"401 [BoIdA4 JO goussoid ‘yanI4 
ey} UOepeuUL ssUTpUNOs ‘(snzuUny 
Imydns ey} Jo yey} pue soroeds 
STq} JO S}JOI W99M40q UOTJOUTISIp Jo 
suvoul [edtoutid 943) 901} 94} U0~ 
snsuny oy} JO SeIpog SUI}IMy jwords J, 


“401 [eoIdA4 Jo gousseid ‘yUNI4 sy? 
U0 SPVU SSUIPUNOS ‘901} 944 UO SNS . 
-un} oy} JO sotpoq suryindy peordé J, 
401 [eoTd 44 Jo gousseld : yun) oy} 
UO 9pvUI SsUTPUNOs ‘sqnjs You! 
PIO 92 JOL VoIdA4 :9014 943 UO sn 
“Uny OY} JO seTpog Surytnay peotdAy, 


ee 


Hee Es ddI pue dx 


é ‘ “ad Lee oF 
HW ‘HM ‘ddI ‘dX 


‘ aM Bee ‘Sa 
HW ‘HM ‘AV ‘ED 


rs é “TJ pue “ad 
wo “A9) “dv, “HW 
HM ‘dT , dam 
‘ddI ‘d& ‘dM ‘SO 


“eqA 
Joqie Ulejsve pues 9g 


"Qa pue ‘7 
‘dk ‘TY Apredrout 


‘s1ajJTuOo 4UB4.10d unt [TV 


"dM ue ‘g 
‘dA ‘Aa i area 
-loulid ‘Ss I9yIuoD 
que,10dult |[@ 2sowlTy 


aS eels 
firm 5 


HM “T. 
sJayIu00 
queyiodwmt 9} 


uv 


*(@ pue 
Iz ‘ssy) ysni ourd 
‘9eIPUBUIOD UINT}ICU 
-O1Q :SULIOJ I9YSTIq 
pue [[e3 ‘soprolods 
-09[00 wny1eUuo01,D 


"(61 “8Y) 9040/}STUI 
“dds eAysjournozeyy 
"CAT 
*3y) Bjyoyoyd Ayeus 
‘esodipe eyoroyg 


“(GT “3y) SeuI0.T 
yoor ‘snsouue soul0q 


“(eT ‘8y) vli0d repoo 
UMOIq ‘“WITeM vlIOg 


“CIT 
‘3y) snsuny [eyo 


*‘SI[BULOTJJO somo 


"(6 39) 
snzunj imydyns ‘sn 
-einydins sniodsjog 


‘(2 “By) snsuny 4[9q 
-pol ‘ejoorurd seui07 


' 


**(eg *By) sIoyueo oUTg |*-**~“sIoxURO PUR s[TeH 


"(02 

*3y) Spinq 90Je[}sIW |°*"""°" "77" Armfut pang 
“(ST *(aepnodto 

‘3Y) JO1-j1v0eq MOT[IA | ‘ULIOJIUN)  4OJ1-yUNI, 
"BOT 141g 04UT 399] g 07 
“(OL dn s}001 wi01j ‘(1epno 

*3y) yor AZu0ds 0414 MM | -dTO ‘ULIOJIUN) 4OI-43Ng 
“20 
“(PT “3y) 901 =| 49Nq OFUT 99} g 07 dn 


poyeurure, AMO[[aX | S}JOOI wWOIP ‘yo1-43ng 


"901 94} JO qed 10d - 
-dn soidno00 gx Ut 
(9017 011}U9) JO1-YUNIT, 


"(I “sy) 401 
Ivey WMOIG YSIPpey 


“(OT “3y) 404 
-qivey UMOIG YSIPpey | ---- og 


-(enoato 
‘uniojyrun) 401-yUnIY, 


. —*(g *8y) 


18 BULLETIN 658, U. S. DEPARTMENT OF AGRICULTURE. 


It is readily seen that Table I will aid greatly in determining the 
rot in the tree by means of external characters, and after the class of 
defect and the cause have been determined by its use it will be com- 
paratively easy to select the proper rot column in the table of rot 
percentages for any one tree species. In this manner the two tables 


can be used conjunctively in securing a more accurate rot percentage 


for the stand.t. Until it is possible to obtain accurate data from a 
large number of trees of all the species composing the prevalent 
forest types of this 
region, no table of 
rot percentages will 
be presented. — 
Since the type 
lines are sketched on 


on the basis of age 


to study and record 
the rot data upon 
such a basis. This 
will make it easier 
to produce patholog- 
ical maps of the 
area by using white 
prints from the type- 
sheet tracings of the 


In a unit crew 


| onsisting of two 
Fig. 18.—Typical rot of the scaly Pholiota in grand fir. come & . 
Note the horizontal streaks formed by the yellowish felty Men (an estimator 


sb Seaicg and a topographer), 
the estimator can be trained to determine the cause of the dis- 
ease and the amount and therefore the rot percentage, recording 
such data accurately for the strip which is being surveyed. Since 
the estimate sheets have blank spaces for the recording of all disease 
and other injuries suffered by the stand, as well as for the estimated 
loss in cull due to each, the only change that a more intensive disease 
survey will incur will be the additional work done by the topog- 
rapher. He will be required to indicate upon his map the boundaries 


pe gun {1 IMU} timber survey maps. 


etric!'system < 


1Weir, J. R. Difficult problem of the control of fungus diseases in the forest. In 
Timberman, vy. 14, no. 9, p. 27-29, illus. 19138. 

Weir, J. R. Some problems in conservation with reference to forest hygiene. In Tim- 
berman, v. 14, no. 11, p. 28-31, illus.. 1918. z 

Meinecke, E. P. Forest tree diseases common in California and Nevada.. Washington, 
D. C. 1914. These publications may be found useful in the determination of various 
kinds of defects. 


class, it will be 
found advantageous - 


the topographic map > 


‘ 


a 


FOREST DISEASE SURVEYS. 19 


of the various infections and to show therein the estimated cull due 
to each. This information can easily be secured by coobservation 
with the estimator, who can supply the actual figures for the rot 
percentages and aid in determining the boundary lines of infec- 
tion. This will produce sufficient reliable data upon which to base 
valuable pathological maps, which can be compiled either with col- 
ored. areas to indicate the diseases and inclosed figures indicating the 
rot percentages or can be drawn in black and white, using lines dif- 


Fic. 19.—Razoumofskya campylopoda, mistletoe, on yellow pine. 


fering from type lines to indicate the boundaries of the infected 
areas and placing the rot percentages in figures within this area. 


PATHOLOGICAL MAPS. 


Maps indicating the distribution of diseases in forest areas have 
not been used to any great extent. In German literature, articles 
are to be found dealing with plant diseases which have such maps 
illustrating the distribution of the disease. Very few contain maps 
dealing with the distribution of forest-tree diséases and none at 
all dealing strictly with the distribution of fungous infection in 


_ forests. : 


In this country considerable use has been made of disease-distribu- 
tion maps by the various workers along the line of plant and forest 


Try 


20 BULLETIN 658, U. S. DEPARTMENT OF AGRICULTURE. 


pathology. This is noticeable in the work done in the study of the 


chestnut-blight fungus’ and in the study of two of our important. 


forest-tree rusts.? These are all maps of the plain black-and-white 
type, showing by means of symbols the localities where infection 
was reported and thus indicating the distribution of the disease. 
The earliest colored maps used in forest-disease investigations are 
found in German literature and deal mainly with the distribution of 
zones of timber damaged by smelter fumes. 


hae 


Fig. 20.—Mistletoe burl affecting one side of larch log. Size of burl, 334 feet long by 
13 inches in diameter. The cull equaled 25 feet board measure. 


Colored maps giving the distribution of smelter-smoke damage 
were published in a book on smoke damage to vegetation by 


1 Rankin, W. H. Field studies on the Endothia canker of chestnut in New York State. 
Phytopathology, v. 4, no. 4, p. 2387. 1914. 

2 Spaulding, Perley. The blister rust of white pine. U.S. Dept. Agr., Bur. Plant Indus. 
Bul. 206, 88 p., 2 pl. (1 colored). 1911. Bibliography, p. 61-78. Map showing 
distribution of blister rust in Europe, p. 14. 

Hedgcock, G. G., and Long,,W. H. A disease of pines caused by Cronartium pyri- 


forme. U. S. Dept. Agr. Bul. 247; 20 p. 1915. Literature cited, p. 20. Map showing 


distribution of Cronartium pyriforme, p. 8. 


FOREST DISEASE SURVEYS. 3 oF 


Schroeder and Reuss in 1883.1. Other works by Schroeder and 
Schertel in 1884? and Borggreve in 1893 * also give maps in connec- 
tion with studies of smoke, the latter maps being uncolored. No 
references were found which contained colored maps of the dis- 
tribution of forest-tree diseases. 
In the making of timber-survey maps, type boundaries are indi- 
cated by continuous dotted lines inclosing within the areas so 
formed the figures 
indicating. type 
mixture, density, 
and age class, the 
age class also being 
separated by dotted 
lines. Very often 
these areas are col- 
ored by the use of 
wash inks or cray- 
ons, so as to make 
a greater distinc- 
tion between them. 
A number of stand- 
ard colors are used 
and are applied 
upon white prints, 
which are found to 
give the best re- 
sults. A similar 
method is proposed | 
for use in making | 
pathological maps, 
the only variation 
being the addition 
to the type-sheet 
maps of boundary 


lines indicating the Fig. 21,—Cronartium colcosporioides, pine rust, gall form, 


infected areas and on young lodgepole pine. The two galls on the main stem 
: are fruiting. Note the small white cups scattered over the 
a special set of col- ee | ps 5c 


surface of these two galls. 
ors indicating va- 
rious diseases. In the pathological maps only those colors Aeatoe 
the various infections should be used, leaving the type areas uncolored. 


1 Schroeder, Julius von, and Reuss, Carl. Die Beschiidigung der Vegetation durch 
Rauch und die Oberharzer Hiittenrauchschiiden. 333 p., 2 maps (colored). Berlin, 1883. 
2Schroeder, Julius von, and Schertel, A. Die Rauchschiden in den Wildern der 
umgebungder physikalischen Hiittenwerke bei Freiberg. Separat-Abdruck Jahrb. Berg. w. 
Hiittenw. Koénigr. Sachsen, 1884, p. 93-120, map (colored). 1884. 
. 8’ Borggreve, B. Rauchbeschidigung in dem von Tiele Winkler’schen Yorstreviere 
Myslowitz-Kattowitz. 236 p., 2 maps. 1893. 


yi BULLETIN 658, U. S. DEPARTMENT OF AGRICULTURE. 


The maps will be found valuable not only as an interpretation of 


the data taken in intensive disease surveys in connection with timber 
surveys but in the appraisal, marking, and general administration of 
the sale area. With regard to appraisal the map will indicate the 
location of seriously infected areas and also the rot percentages. 
With respect to marking, the map will show the exact area of the 


Fig. 22.— Cronartium Fig. 23.—Cronartium coleosporioides, pine rust, blister 
coleosporioides, pine form, an old infection, on the main trunk of lodge- 
rust, blister form, pole pine, known locally as ‘‘ hip canker” or ‘“‘ cat- 
on 2-year-old_ seed- face.”’ 


lings of yellow pine. 


most seriously infected trees and aid in the exclusion of infected 
trees for seed trees. From the standpoint of general administration, 
the maps will show the location of sites and age classes upon which 
heavier marking must be employed in order to conform with the most 
effective sanitation clauses. c | 

With regard to reforestation by artificial or natural means, these 
maps will show the proximity of infected stands'and whether or not 
the site has been or apparently is favorable to excessive disease. 


a? ee awe | 1 


i 


Se Ae ee pe tn be a 


> Peel pitt Ate ee 


~ 


FOREST DISEASE SURVEYS. oe 
' SUMMARY. 


Forest disease surveys when carried out in conjunction with tim- 
ber-survey projects will furnish data of economic value in. conducting 
future sales of the areas in question. 

Pathological maps indicating the principal infection areas can be 
compiled from the data secured by these forest disease surveys. 

These maps will be found of practical value in the appraisal, mark- 
ing, and general administration of the sale area. They will prove of 
practical use in both artificial and natural reforestation and will also 
prove useful in indicating the general distribution of forest-tree 
diseases in our National Forests. 3 


WASHINGTON : GOVERNMENT PRINTING OFFICE : 1918 


t2 
\ 
aa 
* 


es 
CV 
’ " 
+a 4 
$7735 é 
; Aten 
x t 
2 - K 
= 5 
FX; : 
rs j 
. % A 
Seg 
- i? 
Saki 
Fs 
? 
° 
' 
3 
e 
? A 
‘ 
2 


{5 

4 * 
"7 
§* aint 


Oe 


=“ 


TAY enti 
yEurs 
4 o ey é 


Pi 


: 
: 


BULLETIN No. 722 ¥ 


Contribution from the Bureau of Plant Industry 
WM. A. TAYLOR, Chief 


Washington, D. C. PROFESSIONAL PAPER October 22, 1918 


A STUDY OF HEART-ROT IN WESTERN HEMLOCK. 


‘By James R. Weir, forest Pathologist, and Ernest E. HuBert, Scientific Assist- 


ant, Office of Investigations in Forest Pathology. 


CONTENTS. 
Page. Page. 
iM fat WELTON TS Salo APS ee 1 | Methods used in presenting data...........-. 14 
Present status of western hemlock in. the Infectiomaretice: tts. Sess ee ee 16 
TAP RG i Se re 2 | Relation of decay to site and to age.......... 18 
Echinodontium tinctorium..........-.-....-. 3 | Relation of decay to vigor, crown rating, size, 
Thetungus.and its hosts............2...- 3 HIG WViGlMGMNGeE Rho sae Se Ae noo eee oe 22 
Geographic distribution ................. 5 | Relation of decay to injury and to sporo 
The disease caused by Echinodontium DIOTESHEr ee Sema oo) eee ee ae 24 
TROUT ee eS oe 6m | Theoryiciimlection 6 ee i. Tee ea ee 30 
Outward signs of the disease............. 6.4 DDISCHSSiGnTOLTrestlisi 8.45.0 ee oe A ae 31 
General characteristics of the rot... .. ie 9.4), Methodstohecontroloy 22... 2-252 22 ou ero 24 
- Areas studied and field methods used.....-.. Aikes |) SUimanye ese se et eee, ee eee 36 
INTRODUCTION. 


From the fact that the experience and methods of the European 
countries have been worked out and are at present practiced under 
an entirely different set of conditions, forestry in America is con- 
fronted with the necessity of formulating its own fundamentals as 
regards forest organization, working plan, and general silvicultural 
procedure in the virgin forests of the Northwest. Since a large 
number of the basic principles of an ideal forest organization depend 
upon a proper understanding and appreciation of the progress of 
decay in the forest and the general deterioration of the stand and of 
individual trees, the problem is largely one of a pathological nature. 
The need of reliable figures from which an adequate conception of 
the loss to the forest through the death and disease of individual 
trees or stands and through various other causes instrumental in 
reducing the maximum annual increment is self-evident when any 
attempt is made to establish a rotation or cutting age for any one 
species. It is necessary also to concentrate the collection of these 
data upon a single tree species or ee a single ty Be in order to secure 

63424°—18—Bull. 722——1 


2 BULLETIN 722, Uh DEPARTMENT OF AGRICULTURE. 


figures which can be applied to the practical operations of foroaen , 
Meinecke,' in a recent paper on this subject, has clearly expressed 
the need of concentrated work upon single tree species, with a special — 
aim to secure accurate data adaptable to practical use. In order to 
make a beginning in supplying the fundamental knowledge for a 
solution of some of the more vital problems bearing on the regula- 
tion of the forest with regard to the peculiarities and activities of 
the more economic fungi, a series of detailed studies has been in- 
stituted, beginning with the western hemlock (Tsuga heterophylla). 
In the present study, an attempt has been made to secure for two 
principal types of the typical stand all available data bearing on the 
relationship of decay tp the many factors concerned in its inception, 
development, and spread, and to determine, if possible, which of the 
factors concerned in the life history of western hemlock has the 
greatest influence in the development or retardation of decay. 


PRESENT STATUS OF WESTERN HEMLOCK IN THE TRADES.. 


' The regulation of hemlock in the northwestern forests is probably 
one of the most difficult silvicultural problems with which foresters 
have to deal. Not only ‘has this species for many years in some | 
parts of the West been considered little more than a “‘weed”’ in the 
forest, to be removed in as expedient and thorough a manner as 
possible, but a widespread prejudice on the part of the lumber trade 
has kept the products of western hemlock much in the background. 

The common occurrence of heart-rot, the susceptibility to fire and 
frost, etc., have also led to a much advanced theory. of a general — 
decadence of this really valuable species. Western hemlock can not 
be considered in any sense a decadent tree, as is evidenced by its 
splendid height and diameter growth in localities where it reaches its 
best development. There are approximately 90,000,000,000 feet board 
measure of western hemlock in the United States and Alaska, and — 
most of this is found in Washington and Oregon.? Only recently 
have the millmen placed hemlock upon the market under its rightful 
name. In 1908, 90,000,000 feet of western hemlock were reported 
cut, and this increased to 248,000,000 feet in 1910.2 The rapid 
increase in cut tends to show that the true value of western hemlock 
is hereafter to be recognized and that the prejudice against its name 
is gradually disappearing: 

Several mill owners with whom the subject of the soundness and 
durability of hemlock lumber has been discussed state that too fre- 
quently the lumber decays rapidly after being sawed. This is not 

1 Meinecke, E. P. Forest pathology in forest regulation. U.S. Dept. Agr. Bul. 275,62 p. 1916. 


2 Hanzlik, E. J., and Oakleaf, H. B. Western hemlock; its forest characteristics, aie and uses, 
In Timberman, v. 15, no. 12, p. 25. 1914. 


A STUDY OF HEART-ROT IN WESTERN HEMLOCK. 3 


due to a poor physical quality of the wood, but usually arises from 
the fact that great difficulty is experienced in determining the actual 
extent of the advance decay from the more evident heart-rot when 
the trees are bucked and scaled in the woods. Some of the logs go 
to the mills to all appearances sound, but in reality with a part of 
the log in the incipient stages of decay. Consequently, when the 
log is sawed into boards they check or completely fall into a dry 
crumbly decay when exposed to drying conditions for any con- 
siderable length of time. Such conditions cause a discrimination 
against western hemlock by those who have witnessed this deteriora- 
tion after sawing. A better understanding of the real causes under- 
lying this result and a true conception of the usefulness of hemlock 
wood will aid greatly in removing such objections as the trades now 
hold against lumber sawed from this species of tree. 


ECHINODONTIUM TINCTORIUM. 


THE FUNGUS AND ITS HOSTS. 


With few exceptions, as will be shown, Echinodontium tinctorvum 
_E. and £. (figs. 1 and 2) is the cause of practically all the heart-rot so 
widely prevalent in hemlock throughout the Northwest. Being the 
only hydnaceous fungus of its kind and the only member of its genus, 
something of its history should be given. The fungus was lirst 
described as Fomes tinctorwum by J. B. Ellis from the original speci- 
mens collected in Alaska by J. G. Swan. The teeth were broken 
from these specimens, and Ellis. mistook the pits or scars for pores 
and called it a Fomes.t' The fungus was next collected at Jansville, 
Idaho, by C. V. Piper, who sent it to Lloyd. Lloyd published it as 
Hydnum tinctorum. In a letter to the senior writer, Lloyd states 
that Ellis suggested that the fungus might well be the type of a new 
genus and should be called Hchinodontium tinctorwum. Lloyd used 
this name in his article and it was the first time the name was 
employed. In 1900, Hennings, of the University of Berlin, received 
some small specimens from Japan. Ignorant of the work of Ellis 
‘and Lloyd, he published the fungus as representing a new genus, 
calling it Hydnofomes tsugicola.2 The name Echinodontium first 
published by Lloyd has become so thoroughly established in forestry 
circles that any attempt to depose priority and use any other names, 
which in some respects are far more applicable, for instance, Hydno- 
fomes, would lead to some confusion in the ranks of practical foresters; 
hence the name given by Ellis and Lloyd will be used. 


_1Ellis, J. B. New fungi, mostly Uredinex and Ustilagine from various localities, and a new Fomes 
from Alaska. Jn Bul. Torrey Bot. Club, v. 22, no. 8, p. 362, 1895. 
2 Lloyd, C. G. Mycological notes, no. 1, p. 2-3. 1898. 
_ * Hennings, Paul. Fungijaponici. In Bot. Jahrb. [Engler], Bd. 28, Heft 2, p. 268. 1900. 


4 BULLETIN 722, U. S. DEPARTMENT OF AGRICULTURE. 


The chief gross character by which the fruiting organ of the fungus 
may readily be recognized is a hymenium consisting of numerous 
firm, thick, sharp-pointed teeth of a light-brown color (figs. 1 and 2). 
The upper surface is almost black in old specimens (figs. 3 and 4), 
usually of a lighter color when young, and concentrically zoned, 
each zone representing a year’s growth. In a growing condition the 
outer zone is white or brown, context solid, and of a Mars-orange 
to orange-rufous color.'. The minute characters of the fruiting organ 
are: Spores hyaline, broadly ellipsoid, 4 by 6 u, teeth covered with 


Fig. 1.—Sporophore of Echinodontium tinctoriwm on hemlock. Bottom view, showing fresh hymenium 
or spore-producing surface. 


short colorless sets or microscopic spines. - The hymenium of the 
young growing fungus is by no means toothed in the beginning 
but is typically deedaloid, a character often misleading to the unin- 
itiated when the interior has not been examined. 

On account of its tinctorial property, the powdered fungus mixed — 
with tar or oil is used by the Indians as a war paint. The fungus 
is likewise employed by the Indians of Alaska for medicinal purposes 
and as a dye. For the latter reason it has received the common 
name of Indian-paint fungus. Since an oily alkaloid has been 
detected by the analysis of the fungus, there is a possibility of its 


1 Ridgway, Robert. Color Standards and Color Nomenclature, pl. 2. Washington, D. C., 1912. 


A STUDY OF HEART-ROT IN WESTERN HEMLOCK. 5 


possessing therapeutic properties of some value. Tannin has been 
found in considerable quantities in the fungus. 

From specimens preserved in the Laboratory of Forest Pathology 
at Missoula, Mont., the host range ‘of Hchinodontium tinctorium 
is as follows: Tsuga heterophylla, T. mertensiana, Abies grandis, 
. A. concolor, A. lasiocarpa, 
A. nobilis, A. magnifica, 
‘and A. amabilis. The 
fungus has not been re- 
ported on A. venusta. 
Its occurrence on A. 
arizonica is reported by 
Hedgecock. In the very 
rarest of cases Ff. tinc- 
torium occurs on Picea 
engelmanni and Pseudo- 
_ tsugataxifolia. 'Thefun- 
gus rarely occurs on ally 
but its common hosts 
and is only of economic 
importance in the con- 
sideration of problems 
relating to the genera 
Abies and Tsuga. The 
specimens which reached 
Berlin from Japan grew 
on Tsuga diversifolia. 


GEOGRAPHIC DISTRIBUTION. 


_In view of the fact that 
- many of the more serious 
wood-destroying fungi 3 
are distributed over the ie. 2—E£chinodontium  tinctorium growing out of a blaze, 
world, it is interesting to which was the source of infection. Note the spines on the 
note tliat the geographic re 
range of Hchinodontium tisictoriuim is limited. Except the speci- 
mens from Japan, it has not been found outside of western North 
America. To judge by specimens on hand in the Laboratory of 
the Office of Investigations in Forest Pathology of the Bureau of 
Plant Industry and as reported by others, the range of this fungus 
in North America extends from Alaska to northern Mexico and as 
_ far eastward as the limits of the range of grand fir and hemlock on the 
western slopes of the Continental Divide in Canada and Montana. 


5 poe, G. G. Notes on some diseases of trees in our National Forests. In Phytopathology, 
v. 2, no. 2, p.78. 1912. 


6 BULLETIN 722, U. S. DEPARTMENT OF AGRICULTURE. 


The fungus is most abundant and of greatest consequence in western 
Montana, Idaho, Oregon, Washington, and British Columbia. 


THE DISEASE CAUSED BY ECHINODONTIUM TINCTORIUM. 


OUTWARD SIGNS OF THE DISEASE. 


To be able to recognize or discriminate between the more dangerous 
and less harmful diseases should be a part of the everyday knowledge 
of the forest officer in charge of the marking. The following state- 
ments will be of some value in this respect. 

The decay-producing fungus proper is the mycelium in the wood, 


not the ‘‘conk”’ (fig. 5) without. The appearance of a fruiting body — 


Fic. 3.—Sporophore of Echinodontium tinctorium, showing upper surface. 


is in most cases an index of the intensive development of the fungus, 
at least within a certain volume of the tree infected. It means that 
a good part of the food materials of the heartwood at that point 
are exhausted. A single average-sized sporophore situated on the 
first 16 feet of the trunk for all practical purposes may be taken to in- 
dicate an unmerchantable condition of the heartwood of all points 
below and into the next 16-foot log above the first. A sporophore 
situated well up on the trunk may be taken to indicate undesirable 
material throughout the main part of the tree. Little need be said 
concerning the presence of more than one sporophore. It will be 


observed that the largest usually has smaller ones above and below it. 


7 


A STUDY OF HEART-ROT IN WESTERN HEMLOCK. 7 


This generally indicates that the largest sporophore marks the area 
of greatest decay and that the decay has traveled both ways. In any 
case, trees bearing more than one sporophore situated some distance 
from each other are not merchantable and should be cut down and 
burned or fire-girdled. 

The presence of sporophores on the tree is an indication of a fairly 
advanced stage of decay throughout a good portion of the tree. On 
the other hand, the absence of sporophores does not always indicate 
soundness. A few cases may occur where the tree is so old in decay 
_ that the sporophores have died and fallen away. The discoloration 
_ of the bark at the point of attachment or the hole left by the rotting 


_Fia. 4.—An old sporophore of Echinodontium tinctorium on hemlock. Top view, showing the zonation 
and the relation to intensive decay. 


branch may readily be noted. The old sporophores, which have a 
remarkable resistance to decay, may be observed on the ground at 
the base of the tree. Pounding on the tree is a fairly accurate 
method of determining soundness, down to a particular stage of rot. 
In doubtful cases, remarkably accurate results may be obtained by 
pressing the ear firmly against the tree while pounding. Previous 
to this, the bark should be removed over a small area in order to 
secure an uncushioned sounding point. } 

_ Probably the most practical method for the average marking officer, 
in the absence of visible defects, is the presence of red color a half inch 
or so within the dead branch stubs. This reddish coloration of the 
rot £. tinctorium is an index of an advanced stage, and its appearance 
so far out on the dead branch as to be detected by merely breaking 


8 BULLETIN 1722, U. 8. DEPARTMENT OF AGRICULTURE. 


off the branch is a sure sign of the typical rot within. The red color 
may not show at the base of every branch, in which case several may 
be examined. If the red color does not show after the knot has been 
opened with the corner of an ax, the branch may still show a yellow- 
ish, dry-rot or the usual flinty consistency of a naturally pruned 
branch has given way to a loosened condition of its annual rings. 
This may be taken to indicate an initial stage of the rot only at this 
point, however, for the heartwood of the tree may be entirely decayed, 
due to the fungus having entered at another point. Knocking off 


Fig. 5.—Sale area after logging (private logging operations), showing defective hemlocks left standing, a 
waste of valuable material and a menace to the surrounding forest. Note the ‘‘conks”’ on the trunks. 


a few dead branches with an ax does not require much time and is a 
very good method to use in such a case. 


In general, individual trees growing under suppressed conditions © 


or a type developing in a close stand can be expected to disclose a 
Jarge amount of decay, especially when growing on moist river- 
bottom sites. The slope type of stand must be judged more care- 
fully, and it is often the case that in vigorous stands an infected tree 
will yieid the first two logs sound while the upper portion of the trunk 
will be in the last stages of decay. Under such conditions sounding 
by blows will not be found practicable, but the presence high on the 
trunk of many branch stubs, dead branches, and sporophores will 


aN 


A STUDY OF HEART-ROT IN WESTERN HEMLOCK. 9 


always indicate the true condition. Moist sites of various slopes 
and exposures are generally found to produce a greater development 
of decay, and invariably the older trees in such stands are badly 
infected. This is indicated by the data secured from lumbermen 
given in the pages that follow. The early formation of branch stubs 
through the premature dying of the lower crown due to overshad- 
ing can always be depended upon as an indication of existing decay, 
and it will usually be found that the center of infection is located in 
that portion of the trunk bearing the largest number of dead branches 
or branch stubs. The presence of many branch stubs, the presence of 
branch stubs show- 
ing unmistakable rot 
- colorations, the ap- 
pearance and num- 
ber of sporophores, 
many injuries (in- 
cluding frost cracks), 
old age, and unmis- 
takable signs of re- 
duced vigor are all 
very reliable indica- 
tions upon which a 
marking officer may 
learn to base his judg- 
ment for the. deter- 
mination of decay in 
western hemlock. 


GENERAL CHARACTERIS- 
TICS OF THE ROT. 


The spores of ie 
ae ! Fig. 6.—Cross section of a young hemlock, showing heart-rot at a 
Echinodontvum tinc- + whorlot branch stubs. In this case there are five dead branch stubs, 
torium upon germi- all of which were possible agencies in conveying the disease into 


5 the heartwood. 
nation penetrate the 


host mainly through the dead broken branches or branch stubs 
(figs. 6 and 7). This has been confirmed by the data taken in the 
_ study of the relation of injuries to decay. A few infections are trace- 
able to fire and logging scars, frost cracks, or other injuries.* In a 
few instances, on areas other than those upon which data were 
secured, it has been found that the burls on hemlock caused by 
— Razoumofskya tsugensis were points of infection. | 
The hyphe on germinating follow the central nonresinous heart- 
wood zone of the branch stubs and continue inward to the main 
heartwood of the tre¢ (fig. 8), spreading more or less uniformly up 
and down the trunk from the point of infection. The decay is char- 
re 63424918 Bult. 722-2 , 


10 BULLETIN 722, U. 8. DEPARTMENT OF AGRICULTURE. 


acterized in hemlock and grand fir by its uniformity in occupying 
the heartwood (figs. 4 and 8). In alpine fir the rot in cross section 
takes on a somewhat stellar development, due principally to the 
concentration of the hyphe along certain of the medullary rays. _ 
In badly decayed living trees it is invariably the case that the rot 
not only occupies the entire heartwood of the trunk but the heartwood 
of the branches as well (fig. 9), extending 1 in some of the larger ones 
a distance of several feet,! causing the formation of sporophores at 
some distance from the trunk. , 
The advance rot of Echinodontium tinctorium is very difficult of 
detection and unless accompanied by small brownish discolorations 
or by reddish or 
brownish streakscan 
not be detected with- 
out a very close ex- 
amination. In the 
early stages of the 
decay the wood as- 
sumes a faint yel- 
lowish, spongy tex- 
ture. Sometimes this 
stage is intensified 
by the presence of 
small, hardly dis- 
cernible brownish 
areas, which later de- 
velop into the typi- 
calrot. The exten- 
sion of the advance 


Fic. 7.—Section of hemlock, showing a branch stub asa meansoffirst rot beyond the typi- 
infection of heart-rot. The decay has commenced spreading into : 

the heartwood from the end of the branch tissue. ° cal rot i gr eatly 

: according to the con- 


ditions. Some accurate data are at hand to determine the average 
height of the advance rot beyond the typical rot. Such data will 
be found very useful to scalers in determining the amount of cull to 
deduct from the gross scale in order to cut out all the advance rot 
which might later develop into the crumbly decay complained of by 
dealers in hemlock lumber. Meinecke? states that in the white fir 
(Abies concolor) of this region the advance rot produced by EL. tinctorvum 
extends about 2 to 6 feet beyond the typical rot. From the data 
collected on more than 200 hemlocks of all ages and sizes an exten- 
sion of 1 to 5 feet has been found to be general. A single figure 


1 Weir, J. R. Dostvuaeies effects of Trametes pini and Echinodontium tinetorum. In Phytopathol- 
ogy, V.3, no. 2, p. 142. 1913. 

2Meinecke, E. P. Forest-tree diseases common in California and Nevada, p. 52. 1914. Published by . 
U.S. Department of Agriculture, Forest Service. ’ 


¢ 


A STUDY OF HEART-ROT IN WESTERN HEMLOCK. If 


‘can not be used to express this relation, since it varies with all the 
factors influencing the progress of the decay. As a rule, it would 
be safe to add to the linear estimate of the cull 14 feet beyond the last 
recognizable punky area or area showing the slightest yellowish dis- 
coloration. The typical rot (figs. 4, 8, and 9) is readily recognizable 
and has a characteristic reddish brown to brownish yellow color, 
often spotted with areas of a more vivid rust color and occasionally 
showing streaks or lines of a dark red to reddish brown hue. Its 
texture is very pronounced and this, combined with its color, forms 
the basis for the scaler’s common name for the defect ‘‘stringy 
-brown-rot.” In the last stages of decay the heartwood is entirely 
disorganized, giving place to large cavities in the butt logs and some- 
times in the logs above. The stringy nature of the rot can be readily 
~ seen in this stage and also in the ends of logs badly but not hollow 


' Fig. 8.—Longitudinal section of an old sporophore of Echinodontiwm tinctoriwm on hemlock, showing its 
relation to branch stubs. 


rotted, especially in the grass-stubble effect (figs. 4 and 10) produced 
by the sawing. The brick-red color of the sporophores is often found | 
distributed through the typical rot and in the branch stubs in the 
final stages of decay. 


AREAS STUDIED AND FIELD METHODS USED. 


The areas selected for study lie in the drainage basin of the Priest 
River in Idaho. Throughout this region western hemlock is rather 
evenly distributed, extending downward from the subalpine zone 
into the upper limits of the yellow-pine zone. The species attains 
its best development on damp north slopes and is found greatly 
suppressed when growing as an understory in the dense bottom 
stands. 

One of the factors promoting the development of forest-tree fungi 

of the region is the high annual precipitation. The dry periods of 


12 BULLETIN 722, U. S. DEPARTMENT OF AGRICULTURE. 


the year are comparatively short, so that the sporophores of peren- 
nial fungi may never at any time be entirely dried out. During the 
late fall, extending into December and coincident with the formation 


of new fruiting surfaces of the Indian-paint fungus, rain falls almost’ 


constantly. The average annual precipitation is between 20 and 30 
inches, increasing rapidly with elevation, reaching a maximum of 
more than 40 inches in the higher slopes. 

In the spring of 1915 investigations were begun on the river- 


bottom and slope sites of the Priest River valley in Idaho. The’ 


general altitude of the region is about 2,450 to 2,500 feet. The 
meanderings of the Priest River in former times created a number of 


Fig. 9.—Cross sections ofa hemlock branch in which heart-rot extended 10 feet out from the trunk, showing 
how the larger branches may be affected. 


swamps and bayous, which are filled with water during the greater 
part of the year. The interlying areas are poorly drained. 

The whole region is one of dense forests, composed of western white 
pine (Pinus. monticola), western red cedar (Thuja plicata), western 
larch (Larix occidentalis), Engelmann spruce (Picea engelmanni), 
Douglas fir (Pseudotsuga taxifolia), western hemlock (Tsuga hetero- 
phylla), grand fir (Abies grandis), western yew (Taxus brevifolia), 
western birch (Betula occidentalis), and cottonwood (Populus tricho- 
carpa). : 

The soil is a moist sandy loam, with much alluvial material and 
not well drained on the river-bottom sites. There is a great depth 
of humus, litter, and needles. On the above-described site, ten 


A STUDY OF HEART-ROT IN WESTERN HEMLOCK. 13 


separate plats were laid out, comprising 5.7 acres. The river-bottom 
and slope types were first selected for investigation, for the reason 
that at. these elevations and under the existing conditions grand 
fir and hemlock are heavily diseased. The plats represented a 
variety of age classes, mixtures, and successions. 

The investigations on grand fir and hemlock were carried out 
simultaneously, but the data on the former are reserved for a future 
report. The influences of site and elevation on the distribution and 
amount of decay were considered, and the data were consequently 
divided according to the two sites indicated. In order to get the 
percentage of rot of hemlock and grand fir, a clean cut of these species 


Fic. 10.—Section through a trunk of hemlock, with an old sporophore attached. The stringy nature of 
the heart-rot and the grass-stubble effect due to sawing are both characteristic. 


was made. The trees were bucked in such lengths (16 feet and 
shorter) as to determine the transverse and longitudinal extent of 
the decay; also the point at which the decay was greatest. That 
section of the trunk contaiming the upper extension of the decay was 
fully dissected, in order to determine the exact upper limit. The 
diameter of the rot at each log end was measured and recorded. 
The rot in each tree was measured in detail. A full analysis of the 
stump was also made. A uniform stump height of 18 inches was 
maintained throughout. The age of the tree was determined at this 
point, and four years added to the age at the stump, giving the 
entire age. Before the’ trees were felled, full notes on the external 


1 This average age at stump was secured by taking data on a number of seedling hemlocks in the same 
stand and determining the age corresponding to the stump height of the felled trees. 


! 


14 BULLETIN 1722, U. S. DEPARTMENT OF AGRICULTURE. 


appearance relative to environment, etc., were recorded. Each 
tree was designated by a number. Altogether, 201 trees of western 
hemlock were cut on the ten areas, and about an equal number of 
grand fir. The hemlocks considered in this study are numbered from 
1 to 201. No selection of trees was practiced, but all trees on the 
areas laid out were cut. 

Aside from a few cases of saunas decay, the cause ‘of which 
could not be definitely determined from a chemical and anatomical 
study of the rot alone, the occurrence on hemlock of the more common 
fungi of the associated species was practically nil. In a few cases 
the rot of Trametes pint and Polyporus schweinitzii was found in 
hemlock, but since the merchantable parts of the same trees were 
wholly decayed by Echinodontium tinctorium, all decay of the species. 


on the areas is attributed to the latter. This is equivalent to saying ~~ 


that practically 100 per cent of all cases of decay in living hemlock 
were due to £. tinctorium. This is by no means an unusual condition 


for the region. In fact, the finding of any other fungus working asa 


first agent of decay in fatale is a rarity. 


METHODS USED IN PRESENTING DATA. 


The methods used in preparing the data for presentation and com- 
parison are the result of an attempt at standardizing such factors 
as, in ordinary field observations, are usually determined by an 
ocular method not involving exact measurements. Any attempt at 
standardization of such factors as are included under ‘‘Seriousness of 
injury,” ‘‘ Degree of vigor,’’ or ‘‘Crown rating”’ is bound to meet with 
difficulties. So long as the same standard is used consistently 
throughout the Sao a slight amount of arbitrary standardization 
will not in the least i: the value of the results. 

The total volume of the tree, less the stump, inside of the bark was 
first secured in cubic feet by means of the paraboloid formula,! — 
V=(BH~+2), and the table of basal areas.2. The diameter (inside of — 
the bark) at the stump was used to secure the above figure. The — 
total volume of rot in the tree, less the stump, was secured in cubic 
feet by a similar method. As an experiment to determine the shape 
of the rot column, the outlines of the rot column of several infected 
hemlocks’ were plotted on coordinate paper. It was found that 
these rot outlines conformed closely to the general outlines of the — 
trees. It was also found that the formula used to secure the volume ~ 
of rot more nearly included all the rot found within the trunk than ~ 
did the Smalian method. The dissection of the trees and the plotting © 
of a few of them on coordinate paper showed that the formula as — 


1 Graves, H. S. Forest Mensuration, ed. 1, p. 88. New York, London, 1906. 
2 Graves, H.S. Op. cit., p. 430. 


A STUDY OF HEART-ROT IN WESTERN HEMLOCK. 15 


here used allowed for such rot as was to be found outside of a straight 
line drawn from points on the rot sections appearing at both ends of 
the logs and such rot as was found extending outward from the heart- 
wood along the branch whorls. The advance rot is included in the 
total rot in every case. The rot percentage was secured from the 
two given volumes. 

The basis for classifying the seriousness of injury is given as follows: 

0 = No injuries. | ; 
x = 1 to 4 branch stubs, no frost cracks, and very few miscellaneous injuries 
(less than 2). 
xx = 5to9 branch stubs, one frost crack, and a superficial blaze, logging scar, 
or other slight injury. ‘ 
xxx = 10 to 15 branch stubs, not more than 2 frost cracks, deep blazes, logging 
sears or fire scars, and slight lightning injury. - 
_xxxx = 15 or more branch stubs, more than 2 frost cracks, and heavy injuries 
(injured and broken top, severe lightning, and other injuries). 

The grouping of trees according to the crown class has, in general 
forestry practice, been almost entirely done by ocular estimate. In 
the present study the four gradations of the crown class were taken 
from Forest Service Bulletin 611 and were used with the crown size 
in composing the standard for crown rating. The actual size of the 
crown and the crown class are used to determine this rating. The 
crown sizes in square feet (length by width of crown) for each age 
class are grouped together, the largest and smallest sizes compose the 
extremes of the large and the very small crown divisions, respectively, 
the remainder ranging in order of size between these two. The 

.group is then divided into four equal classes: Large, average, small, 
and very small. The individual trees are then given their respective 
crown rating according to the following outline: 
(1) Crown size, large. (Crown class 1.) * 
_ (2) Crown size, average. (Crown class 2.) 
(3) Crown size, small or onesided. (Crown class 3.) 
(4) Crown size, very small. (Crown class 4.) 

The vigor of a tree is indicated by the size and condition of its 
crown and by the favorableness or unfavorableness of the position it 
occupies, as well as by the narrowness of the sap zone and the fineness 
of its annual rings. The injuries which the tree receives during the 
course of its development also play an important part in influencing 
its vigor. ‘The rating for vigor has therefore been based upon the 
following three factors, in the order of their importance: (1) Width 
of average ring in sap, (2) crown rating, and (3) the degree of injury. 

This rating for vigor at least comes nearer registering the true condi- 
tion than a mere ocular estimate. The fixing of the standard or 
average width (as in 00 where the width is 0.12 to 0.19 inches) was 


! Terms used in forestry and logging. U.S. Dept. Agr., Bur. Forestry Bul. 61, 53 p. 1905. 


16 BULLETIN 722, U. S. DEPARTMENT OF AGRICULTURE. 


secured from a careful checking of all the data and from the table 
by Hanzlik and Oakleaf ‘ giving the average annual diameter growth 


for western hemlock as obtained under average conditions in western — 


Washington. 
Rating of Vigor. 


o=Thrifty.—Width of average ring in sap 0.20 inches and 1 up; 1 in crown 
rating; classed as 0 or x under degree of injury. 
oo=Fair.—Width of average ring in sap 0.12 to 0.19 inches; 2 in crown 
rating; classed as x or xx under degree of injury. 
ooo=Poor.—Width of average ring in sap 0.04 to 0.11 inches; 3 in crown 
rating; classed as xx or xxx under degree of injury. 
oeoo=Low.—Width of average ring in sap 0.03 inches and less; 4 in crown 
rating; classed as xxx or xxxx under degree of injury. 


Other methods specially adapted to develop certain data will be | 


found explained under the headings which follow. 

The size of the average ring in the sap is the most important 
factor in the vigor determinations. The injury ratings (as x or za) 
in the 00 vigor class are intended to give a certain leeway in so far as 
the injuries found on the trees are concerned. Many trees have an x 
rating for injury, yet the vigor as indicated by crown size and by 
width of average ring in sap indicates a thrifty tree. A similar 
leeway is given the other vigor classes. 


INFECTION AGE. 


In studying the life history of a particular type, such as the river- 
bottom type of western hemlock, it becomes evident in the course 
of the work that certain age classes within that type represent a 


definite stage in the development of decay. This has been brought 


out by Meinecke ? in his work on white fir (Abies concolor). The 


factors governing the entrance and development of a fungus in its | 


host tend to determine a certain average age which indicates the age 
of first infection, an age at which the stand is most liable to first 
infection by the fungus and below which the infection rarely occurs. 

Judging from Meinecke’s* discussion of the age of infection, he 


defines it as the age at which ‘‘infection rarely leads to more than | 


negligible decay unless the tree is handicapped by quite unusually 


severe conditions.’ An attempt has here been made more accu- 


rately to define this average age. The youngest trees only were 


used and of these only those which were infected. This age is briefly J 
outlined as the average age of the youngest trees open to first — 


infection by the fungus. 


1 Hanzlik, E. J., and Oakleaf, H. B. Western hemlock; its forest characteristics, properties, and uses. 
In Timberman, v. 15, no. 12, 1914, p. 25-33, tab. 3. 5 

2 Meinecke, E. P. Forest pathology in forest regulation. U.S. Dept. Agr. Bul. 275, p. 47-48. 1916. 

3 Meinecke, E. P. Op. cit., p. 48. : 


Li 


A STUDY OF HEART-ROT IN WESTERN HEMLOCK. 


Table I represents all the trees of the 41 to 62 age class, inclusive, 
taken from plats classed in the river-bottom and southwestern-slope 
types. The 15 and 9 youngest trees of each site (river bottom and 
southwestern slope), respectively, were used to secure an average age 
representing the infection age. This age for each tree was secured 
by means of the formula, A,=A—(V~+V,), where A, equals age 
of first infection, A equals age of tree, V equals volume of rot of 
the tree, and V, equals the average annual increase in rot volume 
for the age class in which the tree is included. This last figure is 
obtained from Table IJ. It was attempted to use the first 15 trees 
of the southwestern-slope type. This gave an infection age of 70 
years but included trees as old as 99 years, while the oldest tree 
of the river-bottom type was only 62 years. In using 9 trees, the 
oldest tree of the slope site is 75 years, giving a more equal 
comparison. | 


TasBLE I.—Data relating to the infection age of heart-rot in western hemlock on plats of 
the river-bottom and southwestern-slope types. 


Approxi- | Probable | Number of 
Age. ae Ree of mate value age of infected 

: ; 3 for V+V1. | infection.! |trees(basis). 
River-bottom type: ? Cubic feet. Years. Years. 
Lo (OSS... post 2 Seo eee 82 0. 07 2 44 
LS WOES soc SoS G0o8 Joc one 83 . 03 if 47 
Soy WES 5 4.6.03. en Cope ee ee 84 - 06 2 52 
Sal (OD0S-socn 4G eS 85 . 68 19 35 
G0 eS. oot eee 86 oz 9 46 
OS WE Sic eioeSbac Sd See eee 87 0 0 0 
Se Wass 0) aae Oe 88 . 36 10 46 

Of SGT. on é6.dhe ioe See 89 ~20 8 49 13 
WEY Es te dn 4s eee 90 19 5 52 
25) SHITE. ovio+ Gee Neate ee 91 . 44 13 45 
AD) WOO. ob adsee oes 92 0 0 0 
GU VG@iug.. ok 93 . 59. U7 44 
Ue CE. 54360 Se Se rr S 94 Leal 32 30 
(OF SOUS s 3. peep eee 95 jadi 32 30 
(A (GGUS... ogee ee 96 12 3 59 

IEE Ses ois ae Foon] ae ws wm ello awiotlnenot -afe ae wines come > 44.5 
Slope type: 3 

Ps Es ae ono oe Ae ih 0 0 0 
29 SPO Si 245 4e ech SSeS eee 2 .07 4 53 
OD WEDS. 5 3 -.S Sete pee eee eee 3 0 0 0 
(A Sees. 2 a0 ae eae er ae 4 0 0) 0 

(OC ROD OS I 5 0 0 0 4 
FO G5 Roe ee 6 aly 9 61 
Te Sie 2 5 Bos oes Soe 7 51 26 46 
WE WGRIS. | SO CSRS aoe fr 8 Bal 6 69 
iS) WETS. 40 SS ete deen ee eee eee 9 0 0 0 

teal seen OEE SE Se ec eee Seen ee Dias in 302 32 


1 Formula: Ay=A—(V+V}1). Vi=0.035. . 
_ 2Site description.—River-bottom flat, very moist; soil not well drained; stand very dense. Almost 
_ allindividuals of the tolerant species, such as western hemlock and grand fir, were overtopped or suppressed. 
3 Site description.—Southwestern slope, partly flat; old-age class of a white-pine type in which the 
hemlock has become a climax species; soil fairly moist and well drained; stand not overcrowded. 


_ Table I shows that the average infection age for the river-bottom 
type is 44.5 years and for the southwestern-slope type 57.3 years. 


It thus appears from a comparison of the results shown in this table 
63424°—18—Bull. 722 3 


18 BULLETIN 722, U. S. DEPARTMENT OF AGRICULTURE. 


that the average infection age for the slope type is higher than that 
for the river-bottom type. This is undoubtedly due to the fact that 
the environmental factors in the river-bottom type are more fayor-— 
able to early attack by the fungus. Crowded stands, much shade 
and suppression, and a higher percentage of atmospheric and soil 
moisture all presumably contribute to the earlier infection in es 
stands situated along the river bottoms. 

It is to be understood that the figures as given in the tables that 
follow are not to be taken as absolute. The small numerical basis — 
for some of the data, especially in Table I and part of Tables II and 
III, and other sources of unavoidable error, make it plain that the 
figures given are to be interpreted as indicative of the true conditions 
and not as an absolute analysis. The general tendencies must first 
be ascertamed and the methods for determining them developed 
before absolute figures are presented. 


Tasie Il.—Average annual increase in the volume of we rot in infected wesiern hem- 
lock trees of the several age classes, on plats of the river-bottom and southwestern-slope 


ty pes. 


Average volume of 
rot (cubic feet). 
Interval - rpc aed 
Age class. ge Se: pete Annual | fected 
. : : _| increase trees 
classes. er between | (basis). 
age 
classes. 
River-bottom type: Years. Years. } . 
46. to S6:V ears woos seta Sk ls ees ee 62,2322 see 0. 27 0 6 
07. 10'62) Vearsiseo. 45 Eile eee eee ee 60 8 55 . 035 7 
63:to 70; years =<. atk a 2 ee eee 66 6 . 82 045 32 
7L-tO‘8O WORKS’... ..c. 228 eee doko eee ee ae eee 75 9 2.23 16 39 
81: to: 90l years: cs. - J52c5e8 200 See pase be ee 86 ati 3. 62 13 19 
91 to LOZ; yeams= 2. 2- aie = eee re eee | 95 9 4.04 05 
HOA COULZO eViCaliSeet cee ee cer an =e ee 114 | 19 4.21 Ol 6 
All age eldsses...-24... ot vag pact ask ads ee ee 225 07 116 
Slope type: 
54:70 70t years: 5326 31). Noe,e age soe oe O2e os oaeeee 12) \ peed 
72 GO 75) YOQES= 2.2256 5 2 eee eee eee 74 | 10 31 02 
90. tO. 991 VeaESs, é 2-22 Aas in pee era eee 94 20 1.42 - 06 
1LOL:TOAZ0y cars, .22) Seco e ee eo ee eee 110 17 14.31 81 
134 to160. yeas. <5 neck sees eee ee 149 38 16. 89 07 
162 toDL7O years 5402S 228. 5 Oe. aene eee 172 23 19.16 .10 11 
184 to 200WearS ==. spose esa oat aoe Se-eneeee 193 21 46. 62 1.31 12 
207 tO: 225 years: © ats. Soa. aero ins eee 216 23 46. 56 a .62 13 
226 0.306: V@alS 522-2 e225 les Socata eae 254 38 73. 43 rida 12 
All age elasses..2. 2 2). 20a arsees nom a ee eer | or ote 24.30 | - 46 | 73 


a Interpolated. 


RELATION OF DECAY TO SITE AND TO AGE. 


Western hemlock, which ranges in decay from 50 to 100 per cent © 
of trees infected in some localities and quite generally so over large 
areas where the species occurs in nearly pure stands, may be entirely 
free from its principal disease (heart-rot, caused by Hchinodontium 
tanctorvum) in some regions. > 


A STUDY OF HEART-ROT IN WESTERN HEMLOCK. 19 


In order to determine the distribution of Echinodontium tinctorium 
and the extent of the damage produced by it as influenced by various 
environmental factors, a series of questions was prepared and sub- 
mitted to the timber and mill owners in all parts of the Northwest. 
In response to a total of 151 letters sent out, 44 replies dealing with 
hemlock were received. A certain number of the replies were con- 
fined to grand fir alone. The replies to the questions were prepared 
by experienced scalers and cruisers, to whom the writers desire to ex- 
press their thanks for the careful attention and willingness shown to 
further the progress of the investigation. In most cases the “conks”’ 
(figs. 1, 2, 3, and 4) of the fungus chiefly responsible for the decay in 
- hemlock for the region were sent by the recipients of the letters. In 
practically every instance the fungus was F. tinctorium. Many of the 
northwestern regions not covered by these letters were visited; hence 
it was possible to gain a fairly accurate knowledge of the range and 
destructiveness of this disease along with the data on other phases of 
the study. Since the questions given out dealt with a variety of 
factors, the information thus obtained is submitted under the various 
sections of this paper covering the particular point under discussion. 
Four of the questions concerned the influence of site on the distribu- 
tion and prevalence of decay. . 

The belief that conditions of soil, moisture, exposure, and altitude 
ereatly influence the distribution and prevalence and the amount of 
decay caused by a particular fungus in the forest is supported by the 
data thus obtained. Out of 44 different observations covering a 
great range of territory, including the entire economic range of the 
tree in the United States, only three observers report a uniform dis- 
tribution of decay in hemlock for all conditions. All other replies 
indicate great differences in the amount of heart-rot as influenced by 
soil, slope, and elevation. The topography and soil of those regions 
from which a uniform condition of defect is reported are so uniform 
in themselves that no great variation could be expected. The ques- 
tion of the influence of the site on the prevalence of the fungus 
Echinodontium tinctorvum, it appears, depends on the moisture condi- 
_ tion of the soil and its porosity and not upon soil quality. The fungus 
_ may occur on hemlock growing on any type of soil, but occurs to a 
greater extent on trees growing on wet, undrained sites. This is 
found to be true at any elevation, showing very clearly that the ex- 
cessive moisture conditions of the site are highly favorable to the de- 
velopment of the principal attacking fungus. The answers indicate 
that the soundest hemlock is usually associated with a rich, well- 
drained soil. In wet, shallow soil the root system can not attain its 
normal position but must stay near the surface. If the soil is suffi- 
ciently loose to enable the roots to penetrate deeply, but is undrained, 


20 BULLETIN 722, U. S. DEPARTMENT OF AGRICULTURE. 


as in semiswamp, bottom sites, decay is prevalent and a retardation 
of growth also results. No relation between the composition of the 
soil and the prevalence of the fungus has been observed. Hemlock 
growing on lime, sand, or clay soils as a base for the regular humus 
layer exhibits no greater proclivity to fungus attack than do other 
species. Of the total answers received, 41 stated definitely that the — 
least defective hemlock was found at the upper elevations and slopes 
and upon well-drained soils. The most defective stands were en- 


CROWN $12E SQRFK 
VOL. ROT - CUFT 
PER 1O TREEF 


ee oee. ROWN RATING 


x DEGREE OF INFECTION 


HIEVGALT - FEET 


* 


S 
~ 
: 
a hy 
a 
¢ 
é 
/ 

¢ 
8 {8 

N 

‘ SEE 


> Re 3.38 S E TOTAL VOL CUFT 


= 
Re 
iS) 
oe 
x 
iN) 


Q ' 
N 
‘ iN 
G IN G I 
8 4 
wy GQ 
I j 
Sun 
nah 
| ‘t 
Teel & hs ROT PERCENT 
PS 


tte 
‘ 
Tey 
JES 
pa 


Sue 
ik 
aS 
7 
e 


Fic. 11.—Diagram showing the relation of various factors to the age classes of western hemlock on plats 
of the river-bottom type. 


countered at lower elevations, on flats and bottom sites, and upon 
poorly drained soils. ) 
As the tree grows older it reaches a certain period 1n its life at which ~ 
its vigor seems to have rached its maximum, after which time the 
vitality of the treeebbs. This is often spoken of merely as old age and 
is the resultant lowering of vigor due to the increased unfavorable 
environment of its surroundings. Many factors enter into this rela- 
tionship, competition with younger and sturdier trees for light, water, 
and food being the principal ones. Not the least of these factors is 
the effect of cumulative injuries received throughout its life. Many 
writers on forest pathology have expressed this opinion, and the data 
following (Table IV) convey a like conclusion. Von Schrenk* states 
that ‘‘it has been pointed out that as trees grow older they become 


1 Schrenk, Hermann von. Some diseases of New England conifers: A preliminary report. U.S. Dept. 
Agr., Div. Veg. Phys. and Path. Bul. 25, p. 51. 1900. 


A STUDY OF HEART-ROT IN WESTERN HEMLOCK. 21 


more liable to insect and fungus attack. An old tree has many 
vulnerable points, such as old branches and wounds,” and naturally 
these injuries open the tree to more and greater infections. Hartig * 
does not believe that old age is a natural inherent condition, but says: 
“Tn itself, the feebleness of old age is not a natural condition attribu- 
table to internal causes. The older a tree is, so much the more 
numerous are the dangers through which it has had to pass, and so 
much the greater is the number of its Injuries and wounds through 
which parasites and saprophytes can find an entrance into its inte- 


CROWN RATING 
TOTAL VOL. CUFT 
YOL ROT-CU FT. 
OT, PERCENT. 
NO.OF SPOROPHORES. 
PER 10 TREES 


ba 
bss 


Fe 
*& ODLGHELE OF INFECTION. 


=| DEGREE OF INIURY. 


A” 


Q 
N 
S 
x 
AY) 
Q 
2S TREES 
co 


Pa 
ae 


y) 
A “Vaeeb oo LACK OF WEOR. 


E 


(Le 


¥ 2000 Pee | eae 


Fic. 12.—Diagram showing the relation of various factors to the age classes of western hemlock on plats 
of the southwestern-slope type. 


rior.” From the data secured by questions sent to a large number 
of lumbermen in the Northwest, it was found that a majority of the 
answers received indicated that the older age classes of hemlock were 
very much more defective than the younger. Mdller? has shown 
: that, with the increase of age in stands infected with Trametes pini, 
there was a corresponding increase in the percentage of trees infected, 
and the data given in Table III and figures 11 and 12 also show 
plainly that with increasing age there is a definite increase in the 
amount of decay. 


1 Hartig, R. Textbook of the Diseases of Trees. Translated by William Somerville, p. 7. London . 
and New York, 1894. 

- 2Moller, A. Uber die Notwendigkeit und MOoglichkeit wirksamer Bowers fille des Kiefernbaum- 

eatsyraramos Trametes pini (Thore) Fries. In Ztschr. Forst. u. Jagdw., Jahrg. 36, Heft 11, p. 677-715, 

- 2pil. (partly col.). 1904. . 


22 BULLETIN 722, U. S. DEPARTMENT OF AGRICULTURE. 


TasBLe III.—Averajes computed from field data relating to heart-rot in western hem-— 
lock based uron trees of the several age classes on plats of the river-bottom and south- 
western-slove ty es. : . 


Vol Pent 
(oubindestas R-t percentage. 


Num- | Diam- Crown 


Lack 
Type and age ber of | eter size | Crown For stand. 
piace foes breast Height. en rating. cats ; 
asis ig et eha8 For 
). Total. | Of rot.| Glass 
Total. | fected. 
trees. 
River-bottom Square 
type: Inches.| Feet. feet. |Degree. 
41 t) 100 years. 113 5.9 47.0 400. 0 3.9} 3.1 7. 2 oe 27.1 \ 96 6 96.7 
101t> 160years 7 8.4 65. 7 609. 5 2.6). 3.4) 15.315 236 23. 6 " 
Slope type: 
4it 100 years. 15 8.4 62.6 574. 2 2.63) 288 AOS . 62 3.1 
101 to160 years 18 13.6 88.9 833.3 2.8) 3.1; 52. 6-1 132205) se25 <a 
161 to 200 years 23 17.5 | 106.0- 761. 6 3.5 | 3.3] 107.6] 33.50] 31.1-|> 3058 90. L 
201 years and ‘ 
ONT oc cistortee 25 21.5.) 117.0} 1,458.6 2.4) 3.5] 175.5 | 59:40 | 33.8 


From the viewpoint of the natural increase in heartwood due to — 
larger size, etc., coincident with age, it is presumed that the amount — 
of decay would increase proportionately. The figures obtained in — 
the case of the southwestern-slope type show this to be not only true — 
in this respect, but the proportion of the volume of decay to the 
total volume of the tree is also much higher. In the river-bottom 
site (Table III) the average volume of rot increases from 1.9 cubic 
feet in the 41 te 100 year age class to 3.6 cubic feet in the 101 to 160 
year age class. In the southwestern-slope type (Table III) a better 
comparison between age classes can be made. Here a definite 
increase in rot volume from the 41 to 100 year age class to the 201 ~ 
year and older age class is evident. Table II also shows an irregular — 
increase in the average annual increase in rot volume between age ~ 
classes, though the general trend of the figures in Table II shows a — 
Daat increase from the younger to the older trees up to the age © 
class 81 to 90 years, after which a gradual decline is noted. ‘This — 
fact might possibly reflect the rate of growth of the tree and therefore 
of the hearewood and indicate a dropping off in rot activity simul- 
taneously with a slowing up of the annual growth. 


RELATION OF DECAY TO VIGOR, CROWN RATING, SIZE, AND VOLUME. 


Decay in western hemlock is the main factor of depreciation outside — 
of fire. No other destructive agency operates upon this tree to cause — 
so much waste and none is so difficult to control. The preceding 
data have shown how the tree, especially when growing in river- — 
bottom sites, is subject to attack by this fungus at an early age, and ~ 
for the youngest age classes the river-bottom type shows a greater — 
average volume of rot than the southwestern-slope type. In the ~ 
data secured from lumbermen of the Northwest it is found that a G 


A STUDY OF HEART-ROT IN WESTERN HEMLOCK. 23 


high rate of decay is general in western-hemlock and grand-fir stands 
and especially so in low, poorly drained bottoms. The hemlock and 
‘also the grand fir reacts more favorably in the sites where the factors 
concerned in the growth of the tree are less favorable to the advance 
of the attacking fungus. | 

The relation which such factors as vigor, crown rating, size, and 
volume bear to the inception and progress of decay has never been 
thoroughly demonstrated. A difficult part of this task lies in ob- 
taining comparable figures to indicate the rating for lack of vigor, 
the crown rating, the degree of infection, and the degree of injury. 
By standardizing these factors on numerical data, a basis for com- 
parison has been secured. In the first part of Table HI are arranged 
the averages of 120 trees, taken from the various plats worked as 
growing on the river-bottom site. In this table the total height 
represents a measurement from the ground to the tip of the tree. 
The crown size is given as the product of the height of the crown by 
the width. The crown rating and lack of vigor are determined from 
the field sheets, according to the standard outlines given. Simi- 
Jarly, the total volume and the volume of rot determine the rot per- 
centage. In the column ‘‘Lack of vigor,’ the figures represent the 
relative numerical values, determined in the following manner: All 
trees (18) of the 101 to 160 age class were grouped together (second 
part of Table III). Three of these trees had a lack of vigor repre- 
sented by 00, 10 trees by 000, and 5 trees by 0000. 3(00) equals 
6(0), 10(000) equals 30(0), and 5(0000) equals 20(0), which gives a 
total of 56(0). This figure divided by 18 gives 3.1(0), which is indi- 
eated by 3.1. This gives a numerical basis for the relative values 
__ of lack of vigor in plotting the graphs. A similar method was applied 
to the data in the column under crown rating, and the results secured 
were used in the plotting of the graphs (figs. 11 and 12). This method 
was also used in the ‘‘Average degree of injury” column in Table IV 
and in plotting points for the graphs in figures 11 and 12. 

The process was applied to the trees of the various plats which were 
growing upon the southwestern-slope sites, and the resulting data 
are arranged in the second part of Table III. Pathological graphs 
were then constructed from each of the two parts of Table IIT, using 
all the factors concerned and arranging the units in such a manner 
as to secure the Jeast confusion in following the individual graphs. 
_ In the graph in figure 11, constructed from the figures relating to 
- river-bottom plats in Table III, the first points to be noted are that 
_ the diameter, height growth, crown size, total volume, and volume 
of rot all increase with the increase in age. This is found to be true 
also in figure 12 (with the exception of crown size), which graphically 
_ expresses the data given for plats of the southwestern-slope type in 
Table III. In searching for those factors most prominent in their 


24 BULLETIN 722, U. S. DEPARTMENT OF AGRICULTURE. 


relations to the degree of infection and included within the first 
eight factors of the graph, there is apparently no one which stands 
out. The factors of height, diameter, crown size, total volume, and 
lack of vigor show increase with increased age, so that no special 
importance can be attached to these in so far as any one directly 
influences the rate of decay. The data herein given are not sufficient 
proof that vigor is the one outstanding factor influencing decay; 
since vigor is expected to decrease with increased age, the parallelism — 
of increased decay and decreased vigor can not be interpreted as a 
direct influence exerted by vigor. No doubt vigor plays an im- 
portant part in the speeding up or slowing down of the rate of decay — 
in a tree, if only this relation could be determined accurately and 
definitely. ; 

The total rot percentage for the entire stand of the bottom type 
is 26.6, as compared with 30.8 per cent for the slope type. This 
slight difference in the percentage of total rot for the two types (where 
a greater difference might be expected) is significant and is no doubt 
due to the fact that under each site are grouped all the trees, ranging 
from the youngest to the oldest. A comparison of the percentages of 
infected and uninfected trees for the two sites shows a striking differ- 
ence in results from different methods of presenting the amount of 
infection in a stand. In the river-bottom type, 97 per cent of the 
trees were infected and 27 per cent of the wood decayed. In the 
slope type, 90 per cent of the trees were infected and 31 per cent of 
the wood decayed. A comparison of these figures indicates that ease 
of infection is the factor in which the bottom type exceeds the slope 
type and the rate of spread of decay in the trunk is less speeded by 
bottom location, if at all. The latter belief seems to be borne out by 
the fact that the rate of spread in the bottom type must necessarily 
have been slow, since the stand was composed of comparatively young 
trees of small heartwood content. 

In the slope type the environment is favorable to the full develop- 
ment of tree growth, with an environment equally unfavorable to the 
development of fungi. The reverse is true of the river-bottom type. 
This is evidenced by the facts brought out in Table ITI (figs. 11 and 12), 
which show that decay is more pronounced in the river-bottom type 
than in the other. The graphs also show that in the 41 to 100 year 
age class (Table III) the conditions for-the best development of the 
health of the trees were far below those for the 101 to 160 year age 
class. 


RELATION OF ‘DECAY TO INJURY AND TO SPOROPHORES. 


The relation of injuries to decay in respect to furnishing entrance _ 
points for infection has been accepted with little opposition, and in 
many instances in culturing fungi it has been found that the opening 


A STUDY OF HEART-ROT IN WESTERN HEMLOCK. 25 


of the protective tissues of the host plant was necessary in order to 
produce infection. A portion of the field data was obtained with the 
principal object of determining the part played by the degree of injury. 
All injuries were noted as to size, height on tree, side of tree affected, 
total number, and condition (whether healed or not healed); when- 
ever possible the age when the injury was inflicted and the time taken 
to heal were also noted. A special effort was made to determine, if 
possible, the particular injury causing the originalinfection. This was 
generally taken to be at the point on the trunk where the oldest sporo- 
phore appeared. Table IV gives summaries for the river-bottom 
and southwestern-slope types, respectively, based upon an age-class 
division of the trees. 


TaBLE IV.—Relation of injuries causing heart-rot to the age and to the total stand of 
a western hemlock trees on plats of the river-bottom and southwestern-slope types. 


Infection traced to— 


Uninfected | Av- 
Branch Frost Broken Miscellane- trees. erage 


: 2, ee >’ |Num- 
Type and age class. stubs, cracks, tops. ous injuries. at ber of 
; Fj trees 
ofin- 
Num-) por |Num-| per Num-| per [Num-| poy |Num-| Per [27% 
ber off cent, |Pet Of! cent, [Pet of! cent, [Per Of} cent. | ber. | cent 
trees ‘| trees. * | trees, * | trees, * . k 
River-bottom type: 
41 to 100 years.......... 103 | 91.2 1| 0 Sle etabs| a Di 1.7 4) 3.5] 1.19 113 
101 to 160 years......... 7 1100.0 Os\trone Quite ees Orr Onl say 2.05 7 
MOLAbee ee sce. oS 110 | 92.5 1 Ji 3 2.5 z 136 4 3.8 | 2014 120 
Slope type: 
41 to 100 years.......... 9 | 60.0 sls Oise 0. neat Opa sek Si lta. |ideo 15 
101 to 160 years......... J2 | 66.6 Or eee Perec 2 jeden Ol LOsGu | 2e 0 18 
161 to 200 years......... 16 | 70.0 1 4.0 3° |, 13.0 3. | 13.0 ON ie Bay 2.5 23 
201 years and older..__. 22 | 88.0 ON een 2) | 18: 0 ] 4.0 Ai eae 2.6 25 
SEO Ss 59 | 72.8 DP 26 Gul 74: 6] 7.4 S529 SEQ 81 


a Windfall sears. 


Table IV shows that by far the greatest percentage of infection was 
attributed to branch stubs (figs. 6, 7, and 8). 

This amounted to 92.5-per cent in the river-bottom type and 72.8 
per cent in the slope type for the total stand in each type. Broken 
tops come second, and miscellaneous injuries, such as windfall and 
logging scars, etc., reached a percentage of 7.4 in the slope type and 
1.6 in the river-bottom type. Grouped under miscellaneous causes 
_ were such injuries as blazes, logging, windfall and fire scars, lightning, 
etc., and a considerable amount of sapsucker injury. The first infec- 
tion was not attributed to a certain injury unless the development of 
a sporophore on it (fig. 2) showed this to be the most apparent point 
of infection. The relative degree of injury as determined upon a 
basis of age class is shown in figures 11 and 12, taken from Table IV 
under the head of “Average degree of injury.’”’ This shows an increase 


26 BULLETIN 722, U. S. DEPARTMENT OF AGRICULTURE. 


in degree of injury with an increase in the degree of infection and with — 
increased age. With increase in age the cumulative chances for 
infection due to injuries of all kinds, and especially to branch stubs, z 
increase appreciably, and it is but tual that the older trees beating j 
many injuries and a high degree of injury should show an equally | 


high degree of infection. 


The two types of stand compared on the basis of the amount of | 
injury are found to vary but little in the general relation between 
the degree of infection and the degree of injury. In both types the | 
groups of higher rot percentage also show a higher degree of injury, | 
and similarly the groups of lower rot percentage show a smaller degree q 
of injury. In both sites the infections traced to branch stubs bore — 
the largest percentage and the frost cracks the smallest. Broken : 


tops in both instances camé second in importance. 


In the southwestern-slope type (Table IV), the percentage attrib- i 
uted to broken tops was larger than in the river-bottom type (Table — 


IV), due to the more exposed location and to the older stand. Infec- 
tions traced to branch stubs in the slope type equaled 72.8 per cent 
of the total, while in the river-bottom type it equaled 91.5 per cent. 
It would appear that in spite of the younger age class the river- 
bottom type developed more infection-producing branch stubs than 
the other. A reason for this may be found in the fact that the 


crowded, suppressed condition of the river-bottom stand was much 


more favorable to the infection of branch stubs than the other more 


open type of stand. The high proportion of branch-stub infections — 


to injury infections can be partly explained by the fact that the 


trees of the river-bottom type, being younger, had fewer injuries. _ 


In the slope type the largest amount of injury was found in the 
oldest age class (201 years and older), and in the river-bottom type 
it was also found in the older age class (101 to 160 years). In the 
slope type 10 per cent of the trees were uninfected, and in the river- 


bottom type a much smaller percentage (3) was uninfected, showing — 
by this comparison a more favorable environment for the athaetang 


fungus in the river-bottom sites. 
The slope type exhibited more frost cracks, broken tops, and mis- 


cellaneous injuries to the stand than the river-bottom type, which is — 
due partly to the older age and partly to the more exposed situation. . 
The wind plays an important part in both the formation of frost — 
cracks and in the broken-top condition of many of the trees. It was — 


particularly interesting to note that most of the oldest and largest 


frost cracks were found to have formed in the hollows between the — 
root spurs. This seems to be more general in the slope type, where - 


the exposure to high winds and the height of the t.ees (in connection 


with low temperature) appears to play an important part in their — 


a = the > 2 


A STUDY OF HEART-ROT IN WESTERN HEMLOCK. ate 


formation. The swaying of the trees by the wind when the low 
temperature has set up a stress within the tissues of the lower trunk 
would cause the cracks to form at right angles to the swaying move- 
ment and in the root-spur hollows, where the least resistance to 
splitting was to be encountered. The swaying of the tree alone 
sets up varying forces of strain and rupture in the lower part of the 
tree, and when the tissues are contracted or prevented by low tem- 
peratures from adjusting themselves, a frost crack eventually occurs. 
Sporophores of fungi, if they develop at all, appear after a certain 
period has elapsed from the time of first infection. ‘This period, up 
to the present time, has not been determined for most of the xyloph- 
ilous fungi, at least not for Hchinodontium tinctorvum. Such deter- 
mination would involve a considerable amount of careful inoculation 
work upon trees absolutely free from fungous infection, which in the. 
case of wood-destroying fungi would extend over a period of several 
years. The relation which sporophores bear to the development of 
decay in the host and to the degree of infection can more easily be 
determined. A careful field study of the tree in question with 
reference to recording all possible data relating to the sporophores 
has developed several interesting facts. Little work has been done 
along this line tending to give actual figures as a basis for con- 
clusions. The data collected are grouped under the two parts of — 
Table V for the river-bottom and slope types, respectively. Under 
the heading ‘‘Position on tree,” the sporophores were grouped to 
indicate whether the northerly growing sporophores. were more 
numerous than those growing on the southerly side of the tree. The 
remaining columns in Table V are self-explanatory with the excep- 
tion of the column headed ‘‘Relative position along trunk.” This 
refers to the vertical position of the largest sporophore with respect 
to the other sporophores on the same tree. For example, tree 
No. 50 had a total of five sporophores, of which the third one from 
the ground was the largest. This condition was expressed by the 
figures 3-5, indicating that the position of the largest sporophore 
was in the center of the group. This method was used throughout, 
and the resulting figures were used to determine whether the largest 
_ sporophore was found more commonly in the center or toward either 
end of the group. 
- The river-bottom type with sahehed to its sporophore data 
(Table V) is in general very similar to the slope type. Out of a 
total of 119 trees, 70 (59 per cent) were sporophore-bearing trees. 
- On these 70 trees a total of 149 sporophores were found, of which 
131 (88 per cent) were living and 18 (12 per cent) were dead, giving 
an average of 1.8 live sporophores to a tree and 1 dead sporophore 
to every 4 trees. These figures show a much larger percentage 


28 BULLETIN 722, U. 8S. DEPARTMENT OF AGRICULTURE. — 


of live sporophores than those of the slope type. Almost all (96 | 
per cent) of the largest were living, which was equally true of the 
sporophores in general. The average height from the ground is 
8.7 feet. The northwest to north-northeast grouping held 53 per | 
cent of the total sporophores, the southwest to south-southeast | 
grouping 27 per cent, the east 9 per cent, and the west 11 per cent. | 
Most of the sporophores are grouped on the northern aspect of the _ 
trunks, with a smaller percentage on the southern. Upon dividing — 
the sporophores into groups corresponding to the eight principal — 
points of the compass, it was found that most of them (23 per cent) — 
were on the northwest side, the next largest on the south a8 per 
cent), and the smallest number on the southeast (3 per cent). - 

The figures in Table V, river-bottom type, relative to the ata 
of sporophores are plotted in figure 11 and show the relation between — 
the degrees of infection and the number of sporophores. To avoid — 
the awkwardness of using such an expression as ‘‘1.3 sporophores” 
in the diagrams, it was thought proper to term this factor ‘“Number 
of sporophores per 10 trees’? and use the same figures after multi- 
_ plying each by 10. This does not alter the comparative value of 
the figures. These data and the pathographs indicate how theg 
increase in the number of sporophores keeps pace with the i increase _ 
in the degree of infection. 

In the southwestern-slope type (Table V), out of a total of 81_ 
trees 54 (67 per cent) bore sporophores in varying numbers. These 
54 trees carried a total of 210 sporophores, of which 141 (67 per 
cent) were alive and 69 (33 per cent) were dead, giving an average of 
2.6 live and 1.2 dead sporophores per sporophore-bearing tree. 
More than half (60 per cent) of the largest were living. These data 
indicate that the number of sporophores increases with increased 
age and with increase in the degree of infection as expressed by the rot 
percentage. ‘This holds true for all the age classes except the oldest, 
which is found to have a smaller total number of sporophores and a 
smaller number per 10 trees than the 161 to 200 age class. This 
may be due to the fact that the maximum sporophore production 
has been reached in the 161 to 200 age class and to the further fact 
that on old trees the older sporophores are often found to have 
dropped to the ground. An average of all the figures relative to 
the vertical position of the largest sporophore gave a figure which 
placed it at or very near the middle point. This would seem to 
indicate that the decay spreads more or less in both directions up 
and down the trunk from the point of original infection; consequently 
the sporophores are produced on either side of the largest as the | 
decay progresses. This is, of course, not true in every case, but the 
average condition is a to be such. | 


29 


Md ‘soroydoiods jsesiv] JO o8B osVIOA YW f£ ‘soloydosods 4so8Iv] Jo o8e O8VIOAY 90 
O *A[10Y}.A10U [TV a : *So01} INOJ AIOAV 0} BUG Q 
iS “IOMO] PUB O[PPTUL W9eM4Og p *popnNyjourl OU Sem IIOJOLIOY} YOU ‘991} 9UO WO 4SOT BYeVp o1oOydorOdg v 
| | 
a "9014 el eet 
q -d1loydoiods 
ec ene ae WUVcehe @eisin Shhh = CS GOS ae ae “SIPPIW. |"" "FAQ 9 Aq 2 [on | eee | OV eit te | Weg at eae tod  osvioay 
7, Bae aCe 1596 mel Ce Cece ie, eRe Te ie BN SEt |) ko ils i oe ee el coe” Med sed Sas Poot ag GRE S | ST NOE) eto le eee GcBe-| 1, 2OR 0200 eae des yu90 dh re0 1 
2 v z L 09 | Sr | 8% iS ele ie at eee e “OIPPIW, |" "8 4q 8 Aq OT | 12 aN alae iia O1Z | 69 ThT | ¥¢ T8 |" “ftoquinN 
i) aera = os | Le ca a>. hel a ae et peer le el ma kd) emerson rr! 
a rte gama 4 GG ce eel lage | 06s iS abs" e AG BcRg" eon ee “¢ AQ IT AQ TI | 6 €l |;8 I] Or) 98 | 08 | 9 | 2 | Sz _ |dJopjopuesiBed 10z 
D. -@ I 7 9t | OT OE 8 Vee OV ek POP ico Agug Aq ere" Opes" = SAqghq9t} Or | OT TST | 00'7| 26 | 62 | 89 | 0% | €% |°>“sIBeA 00% 07 TOT 
ey ie 0 T a ¢ 0 Ce TT A OrOe at, (40 Fe BU 8 i OP aie GAQGAQ6 |Z 6 G8 OT 1S al OF 1Z IT | 8T  |77*Sxe04 Q9T 02 TOT 
Se ae pt eps 8 Lee kee oe ln eee OG alas kes ee “opp |" -g Aq¢ Aq 8] 0 I 0°86 |-20%" FT 0 T I GI \""""sreoA QOT 09 TF 
sil me :3d44 edo[s | 
A Sse eee ae mite toe et te | gy ogee ees | as ial jane! APMED Lo GU Sea A oa mas) a iy eee 
E -a1oydoiods 
hee ot te oa Inge a as rm (ays | Zee ae ee 1 tee Cap (0) +|-#¢ Aq ¥g Aq g |--- ~~ 6 fey A [ie OS: 8 PR i lS el ee Tod  o3tI0A Vy 
2 EOD ca Lebo VELGHE LT 6 Bex WRC trclamee. Aala ena eter: Bes fuel ee ee ee Cae 20Gb. | ee oleae ee LS) dO 28°) 8°86 4 ed 7099 dl ergy 
| Sil PA oa z SUL. OL || -eT Te neh) lees lee PAG TAG Tass 5 Sires ¢4q94q 6! ¢ Oe i” ae 6FI | 8T Tel 102 | 6IT |**zequin 
= —— | [> [| | _$ |__| cr) yer 
cs 0 0 0 L if I g rat T'€1 | #1 Aq $2 Aq € | olpprw | "¢ 4G #9 44 8 | 0 9 OOL [tee 2LE. 2 rae er | 9 Lo |-~ "sivas 09T 0} TOT 
< I 0 z GOL | ST Sle) 88" +19" 1-658 ("7 Aq-y Aq T_|-"reao™y |-“"7 AGi9 hq 6.6 19 |9°9'| ZT | cl | PL | SIL | | SIL |--~"Szeed OOT 01 Te 
: POON “SaYyouy “Ssayouy "SLA 20d A} U10}10q-IOATIT 
ky ; op > 4 
e 5 a 4 = = 5 ou a\e8n z < yun = = 2 a So 2 Z g 2 
Bas Set |x So] ages le Ire Carte Pat | aed out Bs loos g Slick E z 2 
i a = a Teal Se) a “azIg aor “9219 "fe | 8 Be ees) oe ee 
fa) Set ce laser | ge a eure | ee wortsod : o | 4° 5 is el gf 
= ° S ct o4| Bal & © | ap E a p | 3 ° 
Pp #2) 8) 8-|-5 | | os 8 |8e|¢| 8] # | 8s) 
c : g x oa 3 “MOTJIpuo : . ® < : 
a a DB Bete: hue a4 ; ia ee o ” Pe e Fs : “SSBlO Os 
< EB. 5 se | s 
7 201} UO WOT}ISOg “4soT]/eUlg "4S03Ie'T me a S 
: si - Sues 
3 5 = YY. 
—0} pose} WOTJOIUT ‘sotoydoiodg t= z | =i 


"sed hy adojs-usajsamyynos pup 10}109-49art ayn fo szopd Uo saau yoojwmay wsajsan fo 104-).10aY4 07 Burznjas Diop asoydosods fo huvuung— a ae 


30. - BULLETIN 122, U. S. DEPARTMENT OF AGRICULTURE. 


The distance from the ground of the rece sporophore ranges 
from 4.5 feet in the case of younger suppressed trees to 78.5 feet in 
the case of a large 300-year-old veteran. The average height in- 
dicated 39.9 feet. The grouping of the sporophores in respect to 
their cardinal positions on the tree gave some very interesting 
figures. The largest number of the sporophores (38 per cent) was 
found in the northwest to north-northeast grouping, 27 per cent in — 
the southwest to south-southeast, and 21.5 and 13.5 per cent in | 
the west and east groupings, respectively. Upon dividing the — 
sporophores into groups corresponding to the eight principal points ~ 
of the compass, it was found that 25 per cent were on the north — 
side, the next largest on the west (21 per cent), and the smallest — 
number on the southwest (4 per cent). The data for the slope type — 
show the largest number on the northerly side of the tree. No — 
such overwhelming percentage was secured as in the work of Moller,! — 
who assembled data on the sporophores of Trametes pini (Brot.) Fr. ~ 
and found that 45.8 per cent of the sporophores appeared on the — 
west side of the tree and 89.4 per cent on the westerly side. This — 
westerly side included all sporophores listed in the north, south, and — 
west columns. 

Figure 12, the southwestern-slope type, represents in the respec- ~ 
tive column the sporophore data taken from Table V. The same 
relation is found to exist between the degree of infection and the © 
total number of sporophores as is found in the river-bottom type. 
The number of sporophores per 10 trees ranges from 13 in the 41.to — 
100 age class to 24 in the 101 to 160 age class, exhibiting a con- 
siderable increase between the two. In the slope type a similar ~ 
rate of increase can be noted, which is constant between all the age — 
classes except the two oldest. 


THEORY OF INFECTION. 


Suppression caused by shade combined with a crowded condition — 
of root spacing as well as crown spacing tends to reduce vigor appre- 
ciably. A poorly drained soil having a large amount of soil moisture 
is another factor to be considered in this connection. ch 7 

Upon the vigor of a tree depend all its vital functionings, its ability © 
to enlarge and elevate its crown toward better lighting, to secure 
raw material and manufacture food, to compete with its neighbors, — 
to quickly heal wounds, and to resist attack by fungous enemies. — 
The predisposition or inherent susceptibility of a tree to disease is — 
not considered a sufficient cause for the extensive attack and devel- 

opment of a fungus in that tree. It is believed that low vigor or a © 


1 Moller, A. Uber die Notwendigkeit und Méglichkeit ait Wadecior Bekampfung des Kiefernbaum — 
schwammes Trametes pini (Thore) Fries. Jn Ztschr. Forst. u. Jagdw., Jahrg. 36, Heft 11, p. 677-715, 2 
pl. (partly col.) 1904. 


A STUDY OF HEART-ROT IN WESTERN HEMLOCK. 31 


~ natural weakness in healing injuries, producing resin, etc., combined 
_ with environmental factors is responsible for the intensive and 
_ extensive fungous activity within this species of tree. At the same 
_ time it must be borne in mind, especially in the case of hemlock, 
that such a natural trait as the absence of any great amount of 
protective resin must be considered as playing an important part 
in the entrance of the disease. The foregoing data have clearly 
_ shown that one fungus is responsible for almost the entire amount 
of heart-rot found in western hemlock, that the river-bottom type 
exhibits more decay than the other (comparing the youngest age 
class), that this type also exhibits a remarkably early decay, and 
that as a whole a large amount of heart-rot is te in hemlock at 
_ early periods in its life. 

Dense stands growing in moist, poorly drained soils develop a 
_ large number of suppressed or eth -vigor trees. This is more com- 
monly the case when the stand is overtopped by older trees of 
other species. The low vigor due to the overshading of the lower 
crown causes the early and numerous formation of shade-killed 
branches. These in time produce branch stubs which are believed 
_ to be responsible for most infections by HKchinodontium tinctorwum. 
The shading of the crown, especially the lower crown, not only | 
- causes the eventual formation of branch stubs but produces a moisture 
and shade condition favorable to the germination and entrance of 
the fungus. As a theory of infection for hemlock types, this is 
corroborated by the fact that in thinnings made by cutting out the 
_ more merchantable species the secondary crowns formed rapidly and 
vigorously by an enlargement and thickening of the regular crown. 
_ This fact, coupled with the observation that very few living sporo- 
_ phores were found 10 years after the thinning, strengthens the theory. 


DISCUSSION OF RESULTS. 


As a preliminary to the discussion of the main points brought out 
in the foregoing pages, it is essential to review briefly the main 
silvicultural characteristics of the tree in question. It will then be 
easier to point out the importance of the various factors influencing 
decay and to arrive at certain conclusions regarding the action of 
the fungus Echinodontium tinctorium during its life history on the 
host. ) 

The western hemlock, as indicated by its distribution, requires a 
cool and moist climate for its development, and an important fact 
in this connection is its splendid maximum development along the 
western slope of the coast ranges, where it receives an annual rain- 
fall of from 70 to 100 inches.' 


1 Allen, E. T. The western hemlock. U.S. Dept. Agr., Bur. of Forestry Bul. 33, p. 10. 1902. 


32 BULLETIN 722, U. S. DEPARTMENT OF AGRICULTURE. 


Its moisture requirements seem to be the principal limiting factor 
of its distribution, since it is found growing on a variety of soils. 
Its altitudinal range extends from sea level in Alaska, British Colum- | 
bia, Washington, and Oregon to an altitude of 6,000 feet, and in — 
Idaho and western Montana it is found at a maximum altitude of | 
5,000 feet. It is always at its best in cool moist draws or north slopes. — 
Regions with a relatively high humidity favor its development, 
although at some of the higher altitudes the humidity i is much less 
than in the bottom-land sites. 

A very tolerant species, it is found to thrive in Idaho and Montana 
in the white-pine type, generally in a mixed stand. Referring to its 
tolerance, Sudworth ' says it is “very tolerant of shade throughout — 
life, especially in seedling stages. In later life vertical light is neces- 
sary for best growth. Allowed overhead light; it recovers remarkably _ 
well from long suppression and renews rate of growth. Prolonged — 
suppression in dense shade greatly checks growth. It thrives in cool, 
open, humid places with abundant soil moisture.” 

No natural thinning takes place under normal conditions, and in 
mixed stands the pruning of the lower branches is a slow and imper- 
fect process. Shade causes the lower branches of the crown to die, 
and these remain on the trunk until broken by wind, windfalls, or 
other causes. This condition leaves the tree with a large number of 
branch stubs open to infection by fungous spores. 

Hemlock in its green condition contains 40 to 60 per cent of its own 
dry weight of moisture,’ a relatively large amount compared to the 
other trees of the rele This fact has a direct bearing upon the 
action of the fungus in the heartwood and accounts for the water- 
logged condition of the base of the tree which is often encountered in 
stands growing on poorly drained soils. 

- In summing up the points brought out by this study the most pro- 
nounced results are found in the variations in the action of the decay 
in the two types studied. A glance at the plat descriptions given for — 
each type (Table I) will show the variation in slope and exposure as" 
well as the marked difference in soil and atmospheric moisture. The 
river-bottom type, growing as a dense suppressed stand on a heavy 
undrained soil in close proximity to the river and to its numerous 
sloughs, presupposes its greater susceptibility to the attack of the 
fungus. In the absence of trees of an older age class it can only be ~ 
assumed that the rot percentage would increase with age. The fact — 
that the rot percentage in the older age class was lower does not 
invalidate this assumption in view of the small number of trees it — 


* east ng Li 


esis 


1 Sudworth, G. B, Forest trees of the Pacific Slope, p. 95. 1908. Published by U. 8. Department of 
Agriculture, Forest Service. 

2 Hanzlik, E. J., and Oakleaf, H. B. \Vestern hemlock; its forest characteristics, properties, and uses. 
In Timberman, v. 15, no. 12, 1914, p. 25-33, tab. 3. 


A STUDY OF HEART-ROT IN WESTERN HEMLOCK. 88 


contains. The total percentage of infected trees as well as the total 
rot percentage of this type in comparison to the slope site bear out 
this statement (Table III). The relation of moist sites to the degree 
of infection of a stand has been noted by Hartig,' who says: ‘The 
climatic conditions peculiar to a given district may render it especially 
liable to outbreaks of certain diseases. Thus, in alpine districts 
proximity to lakes and narrow valleys specially predisposes to cer- 
tain fungoid diseases, because the moist air of such places favors the 
fructification of fungi in a high degree.’’ The loss of vigor due to the 
unfavorable environmental conditions and principally due to sup- 
pression by shade is responsible to a certain extent along with other 
factors in the rapid and universal spread of the decay on this site. 
_ Meinecke ” states: ‘The relative extent of decay by HEchinodontium 
tinctorium is far greater in slow-growing, suppressed white firs than in 
thrifty ones.”’ And in discussing the susceptibility of hemlock to 
injury Hanzlik and Oakleaf * state: “Broken branches and injuries 
to the bark account largely for the spread of conk (Trametes pini) 
and the stringy brown-rot (Hchinodontium tinctorvum), these being 
more abundant in overmature stands and in suppressed stands over- 
_ topped by mature growth.” 3 
That on the river-bottom type the trees are decayed at an earlier 
age, is brought out by a comparison of the data given. The river- 
_ bottom type in comparison with the slope type exhibits not only 
- extensive decay at an earlier age and a younger age of infection but a 
larger number of branch stubs and sporophores for similar age classes 
for the stand. The data secured from the lumbermen of the north- 
western region also aid in determining the fact that hemlock is more 
defective on lower elevations, on bottom or flat sites, and on poorly 
drained soils. 2g | 
In making use of pathological data in the determination of patho- 
logical cutting ages for a stand, the rot percentages as given here for 
separate age classes of the stand are of some value. With the rot 
percentages as a basis (indicating the ratio of the rot volume to the’ 
total volume of the stand for each age class), the forester can deter- 
mine a cutting age for that stand, using all the economic and silvicul- 
tural factors to aid him in a correct determination. The average 
annual increase in rot volume between age classes can also be used 
to advantage in determining the rapidity of increase in rot volume. 
Forest pathology can thus serve to furnish pathological data for 
particular stands, which data can be applied by the practical forester 
wd Hartig, R. Textbook of the Diseases of Trees. Translated by William Somerville, p. 10. London — 
and New York, 1894. 
2 Meinecke, E. P. Forest-tree diseases common in California and Nevada, p. 27. 1914. Published by 


U. S. Department of Agriculture, Forest Service. 
3 Hanzlik, E. J., and Oakleaf, H. B. Op. cit. 


34 BULLETIN 722, U. S. DEPARTMENT OF AGRICULTURE. 


in a solution of such forest-regulation problems as are appreciably 
influenced by the presence of decay in the stand. When once the 
forester reaches the point in his calculations upon a proposed sale 
where he can determine a certain rot percentage as the maximum to be 
considered in a stand in order to secure the required amount of sound 
material at a minimum cost, with this rot percentage as a basis it’ 
wil be comparatively easy to compute the cutting age of that stand. 


METHODS OF CONTROL. 


The methods of control applicable to such types as are here under ~ 
discussion can be little other than extensive. The foregoing data, © 
owing to the small number of trees included in some of the age classes 
and to apparently unavoidable errors, are not to be taken as exact 
in determining the cutting age but are given merely as an aid to this 
determination. Intensive control methods can not be applied to 
logging operations where extensive logging methods are practiced. 
Methods such as can be readily incorporated into the usual routine of — 
logging operations and contorming to the practice of the Forest 
Service are the only ones which can hope to fill the need for forest 
sanitation among the all-practical lumbermen and foresters. Inten- 
sive control can be practiced to a limited extent only upon such sales 
areas as warrant the additional cost. 

The control of wood-destroying fungi is not a matter comparable to 1 
the curative treatment of human disease, but is solely dependent for — 
its success upon prevention. With few exceptions there is no help for 
a stand after it is once attacked by the fungus; hence, if preventive — 
measures are to be effective they must Bree the inteuea or at 4 
least precede the period when the production of spores ona the — 
remaining healthy trees. There are several methods applicable to the : 
hemlock type, and these can be grouped under two heads, sanitation 
clauses in timber sales+ and pathological rotations. Uaeer the 
first come such suggestions as girdling, killing by burning of infectious” 
cull material and piled brush, thinning, and the direct cutting and — 
burning of infected material. Under the second appear such methods — 
based upon a study of the area in question as would lead to a cutting 
cycle aiming to secure the maximum amount of sound material with — 
a minimum risk of future infection and at a minimum of cost. Each 
particular sale area has its individual variations affecting the patho- 
logical condition of the stand. The species in the mixture and the 
relative percentage of each, the slope and exposure, the moisture 
conditions, the cost of logging, the value of the species in the stand 
(in fact, all the environmental and economic factors) have to be 
taken into consideration before an attempt can be made to determine 
a method of control. : 


1 Meinecke, E. P. Op. cit., p.62. 1914. 


A STUDY OF HEART-ROT IN WESTERN HEMLOCK. 35 


A pathological survey of sales areas made with the object in view 
of determining the best method of incorporating sanitation clauses 
or of establishing pathological cutting ages would be’ an important 
step toward a practical and effective means of reducing the, total 
amount of good timber going to waste every year in our forests. 
Girdling by the ax as a method of removal of infected trees left 
standing on a sale area is not to. be recommended as an effective 
means of control. .If the situation allows of no better method, then 
the girdling should proceed, the utmost care being exercised in 
severing all the transporting tissues. The recuperative ability of 
hemlock in regard to the-healing of wounds is very great (fig. 13). 


Merely cutting a cleft in the outer sapwood, leaving the chip in 


Fic. 13.—Cross sections of grand fir (at left) and western hemlock (at right), showing the result of imperfect 
girdling by the use ofan ax. 


place, will not suffice. The wound is very apt to heal, and even if 
it does not the tree may continue to live for years because the trans- 
porting tissues have not been actually severed. It is to be remem- 
bered that the wood of hemlock, owing to its nonresinous nature, 
probably retains its ability to conduct water and food substances 


longer than that of many of its associates; hence it will be found 


necessary to insist upon thorough girdling. Some notable instances 
of the longevity of even thoroughly girdled hemlocks and firs have 
come to notice in which the trees continued to live for five to eight 
years although the bark and part of the wood had been removed 
entirely around the tree for a foot or more. Trees’ under the shock 
of this wounding will sometimes produce as much seed in the year 
following as during several years of normal life. This point is im- 


36 BULLETIN 722, U. S. DEPARTMENT OF AGRICULTURE. 


portant in ‘connection with the girdling sometimes done for the pur- 7 
pose of removing seed trees of ‘idohnrdbi species. 
In view of the need of a rapid destruction of fungus-infected trees, 
viz, those that may not be considered safe to leave on sales areas, — 
there is much in favor of burning the trees severely and allowing 
them tostand. Girdling trees by fire is an old and successful practice. — 
There should be sufficient loppings from the other merchantable — 
trees that when piled about the base of the hemlocks and burned ~ 
will effect their death without much injury to the forest soil or to the — 
seeds of desirable species which may be embedded in the soil. — | 
Thinnings whenever conformable to the conditions of the sales — 
areas are of importance in greatly increasing the vigor and_there- — 
fore presumably the ability to resist fungus attack in the remaining ~ 
infected trees, and apparently reducing the number of viable and 7 
spose peaidbing fruiting bodies produced. 
Under certain conditions where it is found practicable, a method — 
of control by fire can be very effectively used. It has been observed 
that in cases where the down logs of hemlock were left in a suffi- 
ciently shaded and moist situation sporophores of Hchinodontium — 
tinctorium were developed, which were a source of infection to the — 
remaining stand. The cutting of all infected trees and the piling © 
and burning of all infectious cull material along with the brush will 
not only remove the fungus-infected wood but will prevent the 
formation of infection-spreading sporophores. | 


SUMMARY. 


Western hemlock, a tree subject to prejudice by Jumbermen and — 
now beginning to find its place in the lumber markets, is abundantly — 
distributed throughout the northwestern United States and western — 
Canada. 

It is found to be subject to a large percentage of decay, which is 
partly accountable for the prejudice against it. 

Echinodontium tinctorium EK. and E., the Indian-paint fungus, is 
responsible for practically all the decay in standing timber of western — 
hemlock, causing a stringy brown-rot of the heartwood which extends” 
to all parts of the tree. 

In general, the sites and associations of western hemlock are — 
favorable to the development of decay, and the moisture relation 
seems to play an important part in this respect. The absence of 
large quantities of resin, the tolerant habit of the species, the early — 
and abundant formation of branch stubs, and the large number of — 
spores produced -yearly—all these are important factors in the Tae | 
and extensive development of decay in the stand. | 


A STUDY: OF HEART-ROT IN WESTERN HEMLOCK. oe 


The fungus enters mainly through branch stubs. Frost cracks 
_ play a minor part as first-infection injuries. From the point of first 
infection, apparently coincident with the largest sporophore, the 
decay extends up and down the heartwood until all the susceptible 
heartwood is attacked. The extent of decay is found to increase 
with age. A high degree of injury, large numbers of sporophores, 
_ low vigor, and smaller crown sizes appear to develop more or less 
_ parallel with the increase in decay. | 

The environmental factors in the river-bottom type are more. 
favorable to the early and extensive development of decay. A large 
percentage (97) of the total trees of the northern Idaho plats examined 

were found to be infected. Of 10 trees less than 60 years old and 
_ 3.5 inches in diameter breast high, 9 were infected. 

The environmental factors in the southwestern-slope type are less 
- conducive to early decay. The maximum development of the fungus 
is not reached until the stand is old. 

A large number of sporophores are produced on both sites, the 
river-bottom site on a comparison basis of age class showing the 
greater number. The 48 trees over 160 years of age bore an average 

_of 3.7 sporophores per tree. 

Pathological cutting ages based upon data secured by thorough 
pathological surveys and adjusted to the economic factors concerned, 
if applied to all stands of hemlock, would aid greatly in checking the 
spread of the disease and would determine the cutting age of the 
stand before the increase in rot became too great for economic 
logging. In the present study this could be applied to the slope 
type only, since the trees of the river-bottom type are all below 
merchantable size. 

A rigid sanitation clause inserted in all timber-sale contracts 
involving western hemlock should be aimed principally at the destruc- 
tion by fire of all infectious cull material as well as all infected trees 
left standing. Girdling by the ax is not recommended. 

These two control methods, when adapted to the situations they 
best serve, will pave the way to the sanitation of the western hemlock 
stands as well as other types of forests in the Northwest. 


THE PRESIDENT TO THE FARMERS OF AMERICA. 


[Extracts from President Wilson’s message to the Farmers’ Conference at Urbana, Tll., January 31, 1918.] 7 | 


The forces that fight for freedom, the freedom of men all over the world as well as 
our own, depend upon us in an extraordinary and unexpected degree for sustenance, — 
for the supply of the materials by which men are to live and to fight, and it will be — 
our glory when the war is over that we have supplied those materials and supplied ~ 
them abundantly, and it will be all the more glory because in supplying them we 


have made our supreme effort and sacrifice. 


In the field of agriculture we have agencies and instrumentalities, fortunately, — 
such as no other government in the world can show. The Department of Agriculture — 
is undoubtedly the greatest practical and scientific agricultural organization in the — 
world. Its total annual budget of $46,000,000 has been increased during the last — 


four years more than 72 per cent. It has a staff of 18,000, including a large number 
ot highly trained experts, and alongside of it stand the unique land-grant colleges, 
which are without example elsewhere, and the 69 State and Federal experiment 


stations. These colleges and experiment stations have a total endowment of plant 
and equipment of $172,000,000 and an income of more than $35,000,000, with 10,271 ~ 


teachers, a resident student body of 125,000, and a vast additional number receiving 


instruction at their homes. County agents, joint officers of the Department of Agri- — 
culture and of the colleges, are everywhere cooperating with the farmers and assist- — 
ing them. The number of extension workers under the Smith-Lever Act and under ~ 


the recent emergency legislation has grown to 5,500 men and women working regu- 
larly in the various communities and taking.to the farmer the latest scientific and 


practical information. Alongside these great public agencies stand the very effective 


voluntary organizations among the farmers themselves, which are more and more 
learning the best methods of cooperation and the best methods of putting to practical 


use the assistance derived from governmental sources. The banking legislation of — 


the last two or three years has given the farmers access to the great lendable capital 
of the country, and it has become the duty both of the men in charge of the Federal- 
reserve banking system and of the farm-loan banking system to see to it that the 
farmers obtain the credit, both short term and long term, to which they are entitled 
not only, but which it is imperatively necessary should be extended to them if the 
present tasks of the country are to be adequately performed. Both by direct 
purchase of nitrates and by the establishment of plants to produce nitrates, the 
Government is doing its utmost to assist in the problem of fertilization. The 
Department of Agriculture and other agencies are actively assisting the farmers to 
locate, safeguard, and secure at cost an adequate supply of sound seed. 

The farmers of this country are as efficient as any other farmers in the world. 
They do not produce more per acre than the farmers in Europe. It is not necessary 
that they should do so. It would perhaps be. bad economy for them to attempt it. 
But they do produce by two to three or four times more per man, per unit of labor 
and capital, than the farmers of any European country. They are more alert and 
use more labor-saving devices than any other farmers in the world. And their 
response to the demands of the present emergency has been in every way remark- 
able. Last spring [1917] their planting exceeded by 12,000,000 acres the largest 
planting of any previous year, and the yields from the crops were record-breaking 
yields. In the fall of 1917 a wheat acreage of 42,170,000 was planted, which was 


(38) t 


a ee See  eerrrrrcreereorrrrmrmee eer ere 


A STUDY OF HEART-ROT IN WESTERN HEMLOCK. 39 


1,000,000 larger than for any preceding year, 3,000,000 greater than the next largest, 
and 7,000,000 greater than the preceding five-year average. 

But I ought to say to you that it is not only necessary that these achievements 
should be:repeated, but that they should be exceeded. I know what this advice 
involves. It involves not only labor but sacrifice, the painstaking application of 
every bit of scientific knowledge and every tested practice that is available. It 
means the utmost economy, even to the point where the pinch comes. It means 
the kind of concentration and self-sacrifice which is involved in the field of battle 
itself, where the object always looms greater than the individual. And: yet the 
Government will help and help in every way that is possible. 

_ It was farmers from whom came the first shots at Lexington, that set aflame the 
Revolution that made America free. I hope and believe that the farmers of America 
will willingly and conspicuously stand by to win this war also. The toil, the 
intelligence, the energy, the foresight, the self-sacrifice, and devotion of the farmers 
of America will, I believe, bring to a triumphant conclusion this great last war for 
the emancipation of men from the control of arbitrary government and the selfishness 
of class legislation and control, and then, when the end has come, we may look each 
other in the face and be glad that we are Americans and have had the privilege to 
play such a part. 


ADDITIONAL COPIES 
OF THIS PUBLICATION MAY BE PROCURED FROM 
THE SUPERINTENDENT OF DOCUMENTS 
GOVERNMENT PRINTING OFFICE 
WASHINGTON, D.C. 
AT 


10 CENTS PER COPY 
ew 


| 
y” “ ; " 
ae be 
’ ‘ ; ft 
ve , - a 
ees ae | 
5 5 f- 2 . ) 
¥ Poy 
2 ; : ¥ i . 
ny PA -49 my 
. . H 
* ‘ ~ 
4 r : e 
; ae é 
nt, s * . 
“i * ah 
‘ + : tea “v : par Ss , ' Feet ai stot 
[As i s 5 e b ts 
| 1 4 hy ‘eo 
Y i Peet } » Py re 
“ ¥ . x ‘ 
z 4 ‘ . € 
. * , ” f 
: 4 : 
- . ; 
I. i : 
t i f yo , 
4 ¥ 
; - 
, F 
; Hf 
‘ 7 ? : 
‘ , q 
« . ; j 
, 
: ' 
‘ 4 4 
: ¥ 
. 
' 
. f } 
. . =; ML 
‘ 
° 
’ : 
4 ’ 
‘ / ; 
. . : i 
. ’ 
: 
. 
. 
- 
s 
. i 
. 
! 
* 
5 
4 i) 
‘ 
. 
2 » t . 
' 
- 
. LA band 4 
1 


UNITED STATES DEPARTMENT OF AGRICULTURE. 


Contribution from the Bureau of Plant Industry 
WM. A. TAYLOR, Chief 


Washington, D.C. ©= += PROFESSIONAL PAPER November 10, 1919 


ASTUDY OF THE ROTS OF WESTERN WHITE PINE. 


By JAmes R. WetR, Forest Pathologist, and Ernest H. Hupert, Scientific As- 
sistant, Office of Investigations in Forest Pathology, Bureau of Plant 
Industry, Missoula, Mont. 


CONTENTS. 

Page. Page, 

UPA SE ES 2G gh a 1 | Relation between rot and various fac- 

Local pathology of western white pine_ 2 tors—Continued. 

Field studies of the rots in western Infection ages a tS tee ae 11 
OE ee ee 4 Ton ji eget ee a ae EO a 13 
Relation between rot and various fac- SPOMODMOLCS = a eee 15 
api eae eee ee ey Gt) lDiscusston ‘of resultsi22 4 ret eee 19 
aS G?') Methods of. comtwel 2. ee 22 
ee ye LL at ala BA 0015 FNC 1 py age lk lie SS Wn 23 


LOSSES DUE TO FUNGI. 


The estimated stand of western white pine (Pinus monticola) in 
British Columbia, Oregon, Washington, Idaho, and Montana is about 
23,685 million feet B. M., valued at approximately $102,875,000. 
The average loss due to the activities of fungi in western white pine 
for the entire white-pine belt, based on data from logging operations 
in northern Idaho, is 1,658 million feet B. M.1 This figure, 
on a basis of the above given valuation, shows a loss of $7,201,250 
_ from this cause alone. These figures, taken as an average condition 
throughout the merchantable range of the species, indicate the loss 
from decay to be enormous. The limited area occupied by 
merchantable white pine, the adaptability of its wood to a wide 
range of uses, and the ease with which it is worked so establish its 
value as a timber tree that it becomes imperative to investigate any 
cause of financial loss in the species, the amount of this loss, the 


__ 1Based on the recorded data, which give 6.9 as the average rot percentage for the 
entire area upon which the data were collected. The actual loss due to rot would no 
doubt be greater if figured on a basis of cull percentage or actual volume discarded, 
according to scalers’ practice. 


128265°—19—Bull. 799-1 


2 BULLETIN 799, U. S. DEPARTMENT OF AGRICULTURE. 


relation of various factors to the rots, and the means by which the 
loss may be reduced. This, in short, states the purpose of this 
bulletin. | : 


~ 


LOCAL PATHOLOGY OF WESTERN WHITE PINE. 


With the exception of the principal fungus (chinodontimm tine- — 
torium) attacking western hemlock and grand fir, all fungi occur- 
ring on other trees of the western white-pine type attack white pine 
to a greater or lesser degree. Until it is determined that the inter- 
relations of these fungi vary with different species of trees the con- — 
ditions for fungous development may be considered very favorable. 
The western white-pine type of forest is described as having western 
white pine as the key tree and forming approximately 15 per cent 
or more of the stand. In some parts of its range (northern Idaho) in 
young stands western white pine forms as much as 50 per cent or 
more of the stand. The other species in the mixture are grand fir © 
and western red cedar, the predominant trees of the type, and Doug- 
las fir, western larch, western yellow pine, and lodgepole pine. In ~ 
many of the mixtures of the western white-pine type, the white pine, — 
although intermediate as to tolerance, very rapidly gains on its asso- ~ 
ciates and eventually overtops them or may even drive them from ~ 
the stand. One of the results of this suppression of associate species — 
is to promote the activities of fungi in the associate species, which 
in turn react on the white pine. Fully stocked or even pure stands © 
of western white pine may be found extensively attacked. In the 
fully stocked stands the trees do not prune readily, causing the de- 
velopment of larger and older dead branches which are open to 
breakage and infection at an earlier age and also affecting the grade 
of lumber of the tree. In the pure stands, much suppression naturally 
results and fungous diseases are just as prevalent as in a mixed stand. ~ 
Suppression in white pine is not always brought about by overcrowd- — 
ing or by adverse conditions on sites having little protection. Needle — 
fungi may cause retardation by destroying the needles. Lophoder- 
mium pinastri, in its ascigerous stage and also in its pyenidial stage 
(Leptostroma), is a very common needle fungus throughout the 
white-pine type and is a factor to be considered in suppression. 
Mistletoes rarely attack white pine within its merchantable range 
and may be overlooked as a cause of suppression. 

The three main wood-destroying fungi’ for the areas studied are 
Trametes pini, Polyporus schweiniteti, and Fomes annosus. ‘The first- 
named fungus, as the most important, is particularly active in west- 
ern white pine throughout its merchantable range. é 


1Weir, J. R., and Hubert, E. E. Forest disease surveys. U. S. Dept. Agr. Bul. 658, © 
23 p., illus. 1918. 


THE ROTS OF WESTERN WHITE PINE. 3 


The sporophore (conk) of 7rametes pint (ring-scale fungus) is 
brown, woody, usually stratified, and varies in shape and thickness. 
The usual form in the Northwest is a thin shell or scallop shaped 
structure, but it may become hoof shaped or resupinate, depending 
upon the position of the substratum or point of exit. Owing to the 
’ tendency of the mycelium to spread more rapidly vertically than hor1- 
zontally in individual annual rings, a cross section of an infected 
tree shows the decay in the form known as ring-rot. The wood when 
first invaded by the mycelium of Trametes pint assumes a deeper 
reddish brown than when normal. It first becomes visibly character- 
istic with the appearance of pits in the wood lined with cellulose 
fibers. This is the well-known “honeycomb” stage and is the most 
characteristic stage of the rot. The decay, as indicated above, is not 
uniformly distributed in the heartwood, but the rot column may vary 
in location within the tree. This is also due to the fact that several 
separate infections may occur in the same tree, the diseased areas 
being separated by sound wood. As a butt rot, the general form of 
the rot column is conical, tapering at the upper limits. In the upper 
parts of the tree the rot column may be conical in both directions 
from the area of greater decay or from the point of first infection. The 
range of the vertical extent of the rot column in the tree may be from 
a few feet to the entire length of the tree when acting as a trunk rot 
and from 5 to 6 feet as a typical butt rot. External signs of the 
_ decay are the fruiting ‘bodies, swellings of the trunk in a region of 
earlier infections, especially at branch whorls, due to the tendency of 
the tree to heal the old “ punk knots,” resin flow at swelled whorls 
or other points on the upper trunk, brownish punky material in old 
branch knots from which old sporophores have fallen, hollowness or 
_ punkiness indicated by soundings on the trunk, and the presence of 
various injuries. 

Polyporus schweinitzii (velvet-top fungus) is usually not as con- 
spicuous as the ring-scale fungus, owing to the fact that the sporo- 
_ phore rarely appears on the trunk but usually develops on the 
roots near by, and it may be partly obscured by the forest mold. 
It often appears a considerable distance away from the base of the 
tree. The fruiting body is in most cases stalked, the segments of 
the top incurving and colored a deep, rich brown. The margins 
when in a growing condition -are of a lighter color. It sometimes 
appears from old wounds on the trunk in the form of brackets with 
or without a lateral stalk. The under side of the pileus is yellow- 
ish green, which turns reddish if injured. The fungus usually pro- 
- duces a uniform heart-rot of the butt of the tree. It enters the roots 
_and decays the heartwood and may travel in this manner from root 

to root to neighboring trees. The decay produced is a light reddish 


4 BULLETIN 799, U. S. DEPARTMENT OF AGRICULTURE. 


brown in early stages, but in its typical stage it becomes reddish | 
brown, brittle and crumbly when dry, with a tendency to break ~ 
into cubical blocks. The rot has sometimes the characteristic odor © 
of turpentine. The rotted wood is carbonized by the action of the © 
fungus and the cellulose is reduced. ¥ 

The rot caused by Trametes piné is characterized by the delignifi- — 
cation of the wood cells attacked. White patches of unreduced © 
cellulose are left. The decay produced by Polyporus schweinitei 
seldom advances beyond the first. log and is usually not more than 5 | 
to 6 feet up. The form of the rot column is conical from the base | 
of the tree upward. 1 

Fomes annosus (root Fomes) on the areas studied was least im- — 
portant. The sporophores of this fungus are generally found close 
under the surface attached to the roots and hidden by the forest | 
mold. They are brown above, with a white spore surface and usually — 
very irregular in outline. The early stages of decay range in color — 
from lilac to reddish. In the typical stages the annual layers are sep- — 
arated by the more rapid decay of the summer wood. Im a radial © 
section white-pitted areas with black centers may be prominent. ~ 
Finally the wood is converted into a spongy mass. The fungus © 
causes a resin flow from the base of the tree and the roots. A fine © 
felty mycelium is present under the bark in the early stages of decay. © 
The rot column is uniformly circular in advanced stages and may ~ 
extend from 6 to 8 feet into the first log. 


FIELD STUDIES OF THE ROTS IN WESTERN WHITE PINE. 


Field studies of the principal rots of a particular species of tree — 
which aim to develop results of practical importance must neces- — 
sarily be based on data taken from a large number of felled trees. 
It was decided that 100 trees of each age class for each of the two 
types of site would be a sufficiently large number to insure the best 
results. Seven age classes were determined upon as follows: 41 to 
60, 61 to 80, 81 to 100, 101 to 120, 121 to 160, 161 to 200, and 201+ 
years. These are the age-class divisions used by the Forest Service 
in silvicultural practice in district 1. The two types of site, slope and 
bottom, were used, under each of which the seven age classes were 
ranged. Figuring 100 trees per age class and 7 age classes for each 
of the two types of site gives a total of 1,400 trees upon which 
accurate data on each tree are required in order to be fairly certain 
of the results. | 

Previous to the opening of the summer logging operations, all 
information relative to the age classes, sites, and locations of the 
various sale areas scheduled for cutting in the western white-pine 


Ned dio «= a ‘ Ie 


THE ROTS OF WESTERN WHITE PINE. 5 


type in northern Idaho and western Montana during the field season 


of 1916 were secured. With this information plans were outlined 
and arrangements made to secure data on as many of the areas as 


were necessary in order to comply with the outline previously given. 
Thanks are due to the officers of the Coeur d’Alene National Forest 
for their helpful cooperation throughout the season. 

In all, seven separate sale areas and one private cutting were 
covered in the study, and data were secured from each. The Lind- 
berg, Honeysuckle, and Cathcart chances, or sale areas, are located 
within the drainage of the Little North Fork River. -The Tent, 
Silver, and Boro Creeks sale areas are located in the drainage of the 
- main Coeur d’Alene River, near Nelson, Idaho. The Bennett-Miner 
chance is located on the slopes adjacent to the North Fork of the 
Coeur d’Alene River, 20 miles above Prichard, Idaho. The private 
cutting is located near Priest River, Idaho, and is on the Humbird 
Lumber Company’s land. All of the sale areas, with the exception 
of the private cutting on the Priest River, are located within the 
general drainage of the Cour d’Alene River in the Cceur d’Alene 
National Forest of Idaho. All the areas studied are typical of the 
western white-pine type of forest. 

Data were secured on the trees soon after the trees had been 
felled and before any of the logs had been removed by the skidding 
teams. In this manner it was possible to obtain data on a large 
number of trees each day. The entire tree was always available, and 
references to all the trees cut on that portion of the sale area included 
within the study were covered by the data. No selection of in- 
dividual trees or groups of trees was practiced, the aim being to 
record accurate information on the general run of the stand according 
to age class and site. The sawing of the trees into standard log 
lengths of 8, 12, 14, and 16 feet by the logging crews offered splendid 
opportunities to obtain the rot dimensions and other data. The in- 
fected culled logs of merchantable size were opened up sufficiently 
to disclose the rotted area. The top portions of the tree beyond the 
merchantable limit were cut open by the data crew to determine the 
exact extent of the rot in cases where the rot ran into the top. 
Cooperation with the logging contractors and foremen aided greatly 
in keeping ahead of the skidding teams. 

_ For data on the younger age classes not found on the sale areas, 
special permission was obtained to cut certain small areas of the 
younger trees on adjacent areas. 

The trees on both the sale areas and the young age-class plats were 
numbered consecutively as they were measured and recorded, the 
number being placed on the stump, so that no duplication of trees 
occurred. Similar extensive and intensive data were obtained for 


as / 


. 


6 BULLETIN 799, U. S. DEPARTMENT OF AGRICULTURE. 


the white-pine study as were secured for the hemlock study,’ and all 
available factors were taken into consideration in the final results. 
Forest descriptions were written for each sale area, and notes were 
made of the moisture and shade conditions existing on each. 

The data obtained from a total of 1,417 trees, of which 135 were 
grand fir (Adzes grandis), were first arranged according to site and 
age class. While in the field it was found that the number of trees 
needed in the two youngest age classes could be considerably reduced 
from the 100-tree standard. It was found that the trees on the 41 
to 60 age-class in both types of sites, slope and bottom, were uni- 


formly free from visible decay. Owing to this condition and to the ~ 


fact that young white pines of this age class are too small to be 
merchantable and should not be cut needlessly, it was decided to 


reduce the number of trees required. In the 61 to 80 age class it — 


was found that the rots were in the beginning stages, and 60 trees 


per age class for each type of site were considered sufficient. In all — 
the other age classes the number of trees was either above or but ~ 


slightly below the 100 mark, except in the 121 to 160 age class on 


the slope sites, where the number was doubled in order to make a . 
comparison between a similar age class and site for two widely 
separated sale areas, and in the 201+ age class, where it was impos- | 


sible to find more than the recorded number of trees. There was, 


fortunately, one sale area which furnished a fairly large number — 


of trees of the very old age class (201-++). 


Tables were prepared from the data collected, and these will he ; 


volumes were figured by means of the Smalian formula. In these © 


presented in the order of their consideration in the text. The 


tables the word “ Infected” as used at the head of certain columns 
is intended to cover all trees visibly infected. Early stages ot 
infection not determinable by field observations and not measur- 
able as recognized cull are not included. 


RELATION BETWEEN ROT AND VARIOUS FACTORS. 


AGE. 


In Table I are found the data which show the relation between the 
rot volume and the age class of the stand. These data are separated 
under heads of “ Bottom sites” (upper part of table) and “Slope 


sites” (lower part of table), and the data under each head are © 


grouped according of the seven principal age classes. 


Trunk-rot, indicated in the table by the initials T. R., represents ; 
mainly 7rametes pint. Butt-rot, indicated by the initials B. R., 
represents Trametes pini when acting as a typical butt-rot, but in- © 


1 Weir, J. R., and Hubert, E. E. A study of heart-rot in western hemlock, U. S. 
Dept. Agr. Bul. 722, 39 p., illus. 1918. 


THE ROTS OF WESTERN WHITE PINE. 7 


cludes Polyporus schweiniteti and Fomes annosus as well, and Armil- 
laria mellea is sparingly represented. 

In comparing the slope sites with the bottom sites it is well to keep 
in mind that the differences in these comparisons are made even more 
striking by the fact that the average age of the slope type of sites 
is greater by 14 years than that of the bottom type. 

In Table I the average total. volume per age class shows a steady 
increase for both types of site. The trunk-rot for both types also 
shows a definite increase from the 41 to 60 to the 201-++ age class, the 
bottom sites indicating a greater percentage of rot than the slope 
sites. The bottom sites for the 61 to 80 age class show 0.8 cubic feet 
as the average volume of rot and 85 cubic feet for the 201-++ age class, 
as compared to the slope sites, which have 0.055 cubic feet for the 
61 to 80 age and 72 cubic feet for the 201+ ¢lass. The figures for the 
average rot volume for the butt rots on the two types of site vary 


considerably and do not show any consistent increase between the 
youngest and the oldest age classes. The 161 to 200 age class on the 
bottom sites runs extremely high, which may be due to the fact that 
the site from which these trees were taken was very favorable to 
butt-rot and supported a great deal of Polyporus schweinitzii. On 
the slope sites the average is less for the 161 to 200 age than for the 
class preceding it. This again must be accounted for by the local 
environmental] differences present in the varrous afeas upon which the 
trees included in this study were found growing. This is especially 
true of the 201-++ age class on the bottom sites, in which no butt-rot is 
recorded and where the rot is almost entirely due to Trametes pini 
acting as a distinct trunk-rot. 

The “ T. R. + B. R.” column gives figures for the combined rots, 
and in general indicates an increase in rot volume and in rot per- 
centage with increased age. 

Table I shows computations of the average annual increase in rot 
volume between the age classes per infected tree. These figures are 
intended to serve as an approximation of the rate of increase in rot 
volume during the life of the stand and are used later to determine 
the infection age. 

A study of the relation between sound and infected trees reveals 
the fact that as the age increased, the percentage of infected trees in- 
creased at a quite rapid rate. The bottom sites show the more rapid 
increase of the two types of site. It is significant to note that the 
proportions of trees infected for the bottom and slope sites are almost ~~ 

identical, being 55 per cent and 55.3 per cent, respectively. If, in 
order to remove to a certain extent the source of error due to the 
larger percentage of trees of the older age class on the slope sites, 
the averages of the percentages for the different age classes are com- 


8 BULLETIN 199, U. S. DEPARTMENT OF AGRICULTURE. 


pared, it is found that the bottom sites show a greater tendency to- 
ward favoring fungous development. The average percentage of 
infected trees for the bottom sites by this method is 52, and forthe | 
slope sites 47. On the bottom sites the rot percentage is 7.8, and on 
the slope sites 6.1. These figures indicate that although a slightly 
larger percentage of trees was infected (55.3) and although the trees 
were considerably older on an average on the slope sites, the bottom 
sites carry the larger rot percentage. Considering the various areas 
upon which data were taken as a unit, the total volume of rot was 
found to be 13,359 cubic feet and the total volume of the stand 
193,432 cubic feet. This gives a rot percentage of 6.9, or 7.0 figured 
on a basis of 1,282 sound and infected trees, ranging from the 40 
years’ growth to the veterans of 450 and more years. 


TABLE I.—Relation of rots to age classes in western white pime on sites of the 
bottom and slope types. 


[Abbreviations: T. R.=trunk-rot: B. R.=butt-rot.] 
ee 


settee ones). Average volume (cubic feet). Begg) eg 
3 Rot per infected tree. Infected. 
a| 2 
n n”n 
@] & Annual increase 
Age classes. ol = between age 
A re) classes. 
® 
Ee ; 
° © ms 0 >) 
allie he a 4 3 
S § g a - : a ; + E 
Sls|/eo;/8 | m&| S|] ae] eo] & ] B ° 
> =| o o o ° . . ° . Oo 
< | 4 a a & i <a — (aa) a Ay 
Bottom sites: 
41 to 60 years. .... Lay) ee eee 0.99) 0 0 0 0 0 0 
61 to 80 years. .... 73) 21; .16| 30.7 -8| 0 -8 | .04 | 0 - 04 
81 to 100 years... 88) 1d . 72) 82.7 u TY Le Fa Ol ealle 08 | .055 
101 to 120 years... = «1 113)" 25) 167) 15009 | 4525" 204) AON ao .05 | .09 
121 to 160 years... ee 18] 3.12)196.2| 9.5 ]-2.5 19.2 | 229 .007| .29 
161 to 200 years. .. 49) 15. 67|203.0 | 19.0 |281.3 |33.6 | .19 | 5.7 | .50 
20T-F years. ooo 2: 289 109) 18.3 |450.5 | 83.6 1135.9 |85.0 59 | 0 -47 
Total 4 e500 135)\2 eee Sees. 1802 (6146: 12156" |. 22a eee eee 
Slope sites: ceed Sande an ‘saab in 6 
41 to 60 years..... 481 0} 0 24h) 90 0 0 0 0 
61 to 80 years. .... 65} 17) .06; 4.6 03} .14] .055) .0015) .008} .003 
81 to 100 years....| 91] 26 ollewe 2 19 16 17} .006| .001} .0045 
101 to 120 years...) 110] 19) .45) 57.9 .8 295} .6 | .03 . 007) .025 
121 to, 160 years. :.|. 137) 9 27| 2.341789). 5.7 |/6.0. 44.78) 18 +21 | .19 
161'to 200 years. #2)’ 164)" 27) 2362803") C7 Si\toets [ibe |) 200s joeerer 
2014- years.....---| 343] 179] 14. 67/485. 2 | 76.3 {56.0 |72.2 | .38 28 | .36 
i ae rae herr eae | 12--62112,9°4 (16. 7, toon. E) oop eee 
SITE. 


The western white pine is found in situations which supply suffi- 
cient moisture and shade to fill the requirements of the tree. Mois- 
ture plays an important part in its establishment and development, 
and this is emphasized by the fact that the western white pine attains 

| its best growth in the regions where rainfall is plentiful. 


THE ROTS OF WESTERN WHITE PINE. 9 


In order to get a first-hand impression of the characteristics of 
western white pine from the point of view of the logger, question- 
naires were sent to a large number of lumber and logging concerns 
operating in the Northwestern States. Out of the total answers re- 
ceived 18 were selected in which the replies to the questions were 
complete. Most of these answers were received from companies oper- 
ating in the States of Oregon, Washington, Idaho, and Montana. 

In respect to site, most of these answers state that the rot is 
greatest in trees occurring on flat, low, and poorly drained land, and 
that the best sites, where trees are freer from rot, are well-drained 
slopes or benches. Altitudes ranging from 1,500 to 7,500 feet are 
given as most favorable to healthy stands, and conversely the greatest 
proportion of rot is found in stands at altitudes below 1,500 feet. 

In Table I it is seen that thé proportion of rot on the bottom sites 
(7.8 per cent) is somewhat greater than on the slope sites (6.1 per 
cent). Apparently, this difference is directly due to the site and 
corroborates what has already been said in reference to environment 
favorable to fungous development. The above comparison of rot 
percentages for the two types of site is made more exclusive when 
the figures for the percentage of infected trees for each type are 
considered. The difference, presumably, would have been still 
greater if the proportion of the trees on sites of the slope type in 
certain of the older age classes had not been so much greater than 
for sites of the bottom type. In Table IIT a comparison is made be- 
tween two sale areas in the same forest but separated by a consider- 
able distance. The trees occurring on the slope sites only were used, 
and these were restricted to the age class of 121 to 160 years. A 
glance at Table II will show that the trees from the Honeysuckle 
sale area averaged 132 years and those of the Silver Creek sale area 
_ 142 years, a difference of 10 years. 

Taste II.—Comparison of two sale areas of western white pine of the 121 to 

160 age class growing on slope sites, showing the relation of rots to site. 

7 [T. R.=trunk-rot, B. R.=butt-rot.] 


Volume of rot 


Total volume (cubic feet). (per cent). Number of trees (basis). 
‘ Average 
Salearea. | age Rot. Infected. 
(years). (a a TR. ial kcal 
Stand. TR, |T-R.| BR} + | Total.|Sound.| mp | por. 
T.R.|BR| B.R. +” | cente 
iB. B. R. | age 
Honeysuckle. 132 | 22,172 | 323.5 | 96.1 419.5 | 1.45 | 0.43 1.89 122 36 86 70.5 
Silver Creek.} 142 | 18,095 | 536.6-] 1.6 538.3 | 2.96 . 01 2.97 106 24 82 ied 


ee Se ee ee 


128265°—19—Bull. 7992 


7 


10 BULLETIN 799, U. S. DEPARTMENT OF AGRICULTURE. 


This indicates a greater number of the older trees of the 121 to 
160 age class on the Silver Creek sale area than on the Honeysuckle 
area. Continuing the inspection of the data in the table it is seen 
that the total volume of rot, the rot percentage, and the precentage 
of infected trees for the combined rots are all greater in the case of 
the Silver Creek area. The difference of 10 years between the average 
age for the two areas is apparently responsible for the difference in 
the rot activity just noted and gives further evidence that, the site 
being similar, the age of the stand affects the amount and percentage 
of rot as well as the number of trees infected. Eliminating the 


difference in the average ages between the two sale areas, the slope — 


sites of the two areas should yield more nearly equal values for total 
volume of rot, rot percentage, and percentage of infected trees. 


Another interesting point brought out in Table II is the variation — 


in the amount of butt-rot for the two areas. Very little butt-rot 
is found upon the Silver Creek area (1.6 cubic feet) in comparison 
~ to that found on the Honeysuckle area (96.1 cubic feet). 

In Table III comparisons are made between the rot percentages of 
trees occurring on the slope and bottom sites of the same sale areas. 
This method of comparison removes all possible variations which 
might be due to comparisons of plats occurring upon widely separated 


areas. In general, the figures show a higher rot percentage in trees — 


occurring on the bottom sites than in those growing on the slopes. 
On the Bennett-Miner sale area plat 1 was laid out upon the slopes 
and plat 2 on the bottoms. The bottom sites have a greater average 
by 38 years and also a greater rot percentage by 6 than the slope sites. 
In comparing the slope and bottom sites of the Silver Creek plat 1 


area it is seen that the difference in average age is only 4 years, — 


while the difference in rot percentage is approximately 5. Again, in 


comparing the Honeysuckle,plat 1 with the Honeysuckle plat 4 area 


the difference in average age is 7 years and that of the rot percentage 
4.5. The greatest difference in rot percentage is found in comparing 
the Humbird area with the Tent Creek area, between which are found 
differences of 39 years in average age and 7 per cent in the rot. This 
last comparison is not as dependable as the ones preceding, since the 


slope and bottom areas compared were taken from two widely sepa- — 


rated sale areas. Similar criticism also applies to the comparison 


of the Honeysuckle plat 3 with the Silver Creek plat 2 area, which — 


comparison indicates the possibility that the difference in average 
age may not be entirely responsible for the small rot percentage in 
the Honeysuckle plat 3 area. Comparing the same Honeysuckle plat 
3 area with the Honeysuckle plat 1a area it is seen that a difference 


— oe 


in rot percentage of 0.538 is more than balanced by a difference of 50 


‘ years, which latter is no doubt accountable for the larger rot percent- 
age found on the slope sites. 


THE ROTS OF WESTERN WHITE PINE. 11 


Table I shows that for each type of site the rot percentage gradu- 
ally increases from the youngest to the oldest age class, reaching 18 
per cent in the bottom sites and 14.7 per. cent on the slope sites. 
Comparing similar age classes of the two types of sites, the figures 
for rot percentage on the bottom sites run consistently higher than 
those of the slope sites. 

TABLE III.—Comparison of bottom and slope sites of different sale areas of 


western white pine, showing the relation of rots to site, independent of age 
classes. 


Bottom sites. Slope sites. 
Sale area. Num Sale area. Hig Num 

Plat | ber “ol Average; Rot Plat bear's. of Average| Rot 

No. | trees a5e iy No. | trees age e. vos 
Bennett-Miner......... 2 15} 379.1 |20.53 | Bennett-Miner........ 1 | 71 | 340.6 | 14.62 
Silver Creek............ 1 18 | 146.4 | 8.01 Be Stee: eda 1 a 2 2. oS 

? ilver Creek......./..- 2 14 9. ; 

Honeysuckle........... 3 i. 72.0) 002 Gee enekts Seloseccnee la 16 | 122.0 . 54 
1D Ig SS 5. eee ae 1 AT iis Lo Ot De De58 iow zy DOs sa cnaieia oon beds = 4 33 | 118.0 . 70 
Sita... -2-..-|.2 er dae | hoo G | Onde | Dent Orel. s7ac6 ihe Ss 2 241 |} 120.7| 2.19 
JG se ae i eae SYA Jal > Seatac | a Sa Rotalev<s-s4enc spe ALQE os Seo pete 


In comparing the average volume of rot for the two types of site 
in Table I a striking contrast is found between the butt-rot volumes. 
The average butt-rot volume on the bottom sites is found to greatly 
exceed the average volume for the slope sites, the average volume of 
trunk-rot is approximately equal, while the average volume of com-- 
bined rots is shown to be somewhat larger on the bottom sites. 


INFECTION AGE. 


The average infection age, as defined in a previous work,! repre- 
sents the average age of the youngest trees in the stand open to first 
infection by fungous enemies. It is the average age at which the 
stand is most lable to first infection and below which infection 
rarely occurs. Subsequent to this age infection is to be guarded 
against, as the chances of infection, up to a certain point, will con- 
tinue to increase with the increase in age, number of injuries, etc. 

In this bulletin the term age of earliest infection is used in place 
of “average infection age.” It is believed the newer term will more 
accurately convey the meaning intended. 

On the bottom sites, Table IV, the age of the earliest infection for 
the combined trunk and butt rots can be placed approximately in 
the 61 to 70 age class, since the first tree with visible decay is found 
in the 71 to 80 age elise and is 73 years old. It must be remembered 

- that actual infection is expected to take place some time before visible 


-iWeir, J. R., and Hubert, E. E. A study of heart-rot in western hemlock. U. 8. 
Dept. Agr. Bul. 722, 39 p., illus. 1918. 
- 


12 —s- BULLETIN 799, U. S. DEPARTMENT OF AGRICULTURE. 


decay is present in the tree examined, and this fact would tend to 
place the age of earliest infection somewhat below the age of the 
tree at the time visible decay is noted. 


TABLE 1V.—Relation of rot to age classes, with reference to the infection age — 


of western white pine on sites of the bottom and slope types. 
| 


Bottom sites. Slope sites. 
Number of trees (basis). | 4 ver- Number of trees (basis). | 4 ver- 
Age class. age rot age rot 
Average per in- pee er in- 
: Per. fected , Per- | fected 


age 
(years). In- centage tree ence In- |centage| tree 
Total. | tected. | in- | (cubic Total. | tected. : in- | (cubie 


fected. | feet). ected. | feet). , 


—— 


41 to 50 years.....-. 48 16 0 0 0 45 33 0 0 0 

51 to 60 years...... 56 21 0 0 0 56 ty 0 0 0 

61 to 70 years...... 66 21 0 0 0 63 48 2 4 - 035 

71 to 80 years...... 80 41 4 10 79 74 12 2 1 075 

81 to 90 years...... 85 80 26 33 1.78 85 46 10 22 - 213 
17 47 1.38 95 52 1 25 145 


91 to 100 years..... 94 36 


In Table IV the youngest trees found visibly infected on the slope 


site are in the 61 to 70 age class, and the age of the earliest infection 


would be found in the 51 to 60 age class. The youngest tree on the 


slope sites found to have visible decay is 61 years old. From these 


data it appears that the age of the earliest infection would be found ~ 
between the ages of 50 and 60 years, and to be reasongay safe it may — 


be placed at approximately 50 years. 

Most of the answers received from the logging companies in refer- 
ence to the question of the age at which western white pine is first 
infected give 50 years as the approximate age below which very 

little infection occurs. 

It is apparent that factors other than that of site influence the per- 
centage of infections as expressed by the figures in Table I. On the 
bottom site (Table 1), the 61 to 80 age class, with an average age of 
73 years, has only 6 per cent of the total trees infected, as 
compared to 7 per cent on sites of the slope type for a similar 
age class with an average age of 65 years. Density of stand and in- 
juries such as fire scars could well be responsible for the increased 
infection of the trees on the slope sites. Farther along in the table it 
is found that for the bottom sites in the 81 to 100 age class, averag- 
ing 88 years, the percentage of infected trees is 37 as compared to 24 
for the slope sites with a similar age class, averaging 91 years. : 

On both the slope and bottom types of site it is found that the 41 
to 60 age class is entirely free from visible infection; that is, no 
measurable rot recognizable to the naked eye was found in these 


trees. This fact alone would indicate that an age of earliest infec- — 


tion placed at 50 years would be as nearly correct as the practical ap- — 


plication of such an age demands. The site, apparently, is not the 


THE ROTS OF WESTERN WHITE PINE. 13 


determining factor as to the earliest age when infection may take 
place. The earliest visible infection for the groups of trees included 
-in this study was found in a tree on the slope type of site, 61 years 
old. Table I shows that in the 61 to 80 age class the greater percen- 
tage of infected trees is found on the slope sites, while the bottom 
sites have the larger rot percentage. 


INJURIES. 


Since injuries play the principal roéle in the infection of living 
trees, it is important to consider them in relation to the various fac- 
tors such as age and site and especially in relation to the rot volume. 
In Table V are given the data for bottom and slope sites, respec- 
‘tively, showing the relation of injuries to age class and to site, as 

-well as indicating the percentage of infection traced to the various 

kinds of injury. The determination of the particular injury which 

was primarily responsible for the initial infection of the tree was 

most difficult in many cases, and no doubt a few of the individual 
decisions may be classed as doubtful. In the main such factors as the 
appearance of sporophores and the location of the largest ones, the 
region of greatest decay within the trunk, and the overwhelming oc- 
currence of butt-rot in trees having large fire scars at the base give 
substantial evidence for the determination of most of the injuries 
responsible for infection. 

The basis for the determination of the degree of injury rests on 
the following standard : 

0 = No injuries. 

x = 1 to 60 dead branches, no frost cracks, and very few miscellaneous in- 

juries (less than 2). 
xx = 61 to 120 dead branches, one frost crack, and a superficial blaze, logging 
scar, or other slight injury. 
xxx = 121 to 180 dead branches, not more than 2 frost cracks, deep blazes, log- 
ging scars, or fire scars; slight lightning injury. 

xXxxx = 181 to 250 and more dead branches, more than 2 frost cracks, and heavy 
injuries (injured and broken top, severe lightning, and other in- 
juries). 

Dead branches were considered of prime importance in determin- 
ing the degree of injury for individual trees. Fire scars proved an 
exception in a certain group of trees where the fire had caused in- 
juries at the base, and these injuries were believed to be primarily 
‘responsible for the entrance of the fungus. These trees were of an 
age class bearing many dead branches. The younger trees had fewer 

_ dead branches than the older ones. Frost cracks were entirely ab- 
sent in the younger age classes, so that no difficulty was experienced 
such as would arise in case a tree was found having only 60 dead 
branches and bearing 2 frost cracks. The older trees bore the few 
frost cracks found, and these trees had numerous dead branches. 


14 BULLETIN 199, U. S. DEPARTMENT OF AGRICULTURE. 


In rating the averages for the various age classes x was given the 
valuation of 1, xx of 2, etc. In this manner averages such as 0.32 


and 2.9 were computed (see Table V), indicating the average degree — 


of injury. 


TABLE V.—Relation of injuries to age and to total stand of western white pine 
on sites of the bottom and slope types.* 


Infection traced to— Total trees 
wi es EEE SY) ES A MES eS 
. = ead ae De- | Total 
Branch Broken Frost are Scare Wee oreo: ae 
and other | infection of | ber 
Age class. stubs. tops. cracks. injuries. | was traced.| in- of 
jury. | trees. 


ss | | eS | 


Num-| Per |Num-| Per |Num-} Per |Num-| Per |Num-| Per 
ber. |cent.2} ber. |eent.2) ber. jcent.2| ber. jcent.2} ber. jcent.3 


Bottom sites: 


41: to0,60' years! . 02.255 0/ 0 0 “AG O70 0; 0 0. 32 37 
61 to 30 years.; - 3. «~ - 42 3 | 75.0 0 0 0; 0 1 | 25.0 1. 74 62 
81 to 100 years.......... 23 | 53.5 0 0 0; 0 20 | 46.5 2. 09 116 
101 to 120 years... .<.... 50 | 70.4 0 0 0; 0 21 | 29.6 2.6 111 
120 to 160" years:2..<- 2.: 68 | 79.1 0 0 1) i eae BW fy a 6 | 2.9 129 
161 to 200 years......... 65 | 90.3 0 0 2] 2.8 5} 6.9 2.6 76 
201+ ‘years.......-...-- 32 | 84.2 0 0 2] 5.3 4] 10.5 3.0 39 

Vota eds Se 241 | 76.7 0 0 By 16 68 | 21.7 2.4 570 

Slope sites: 

41 to 60 years..........- 0; 0 0 0 Oo; 0 0; 0 0 50 
61 to 80 years..........- 3 | 75.0 0 0 0; 0 1 | 25.0 -16 60 
81 to 100 years.......... 15 | 62.5 0 0 oO] 0 9 | 37.5 Bey 98 
101'to 120 years:- -5-2 2. 26 | 63.4 0 0 0; 0 15 | 36.6 1.41 100 
121 to 160 years......... 137 | 78.7 0 0 1 6} 36| 20.7 rR 235 
161 to 200 years..:...... 47 | 57.3 0 0 3] 3.6 32 | 39.0 2. 68 99 
201-4- years. =. 22. .seeee 67 | 97.1 0 0 0} 0 2) 2.9 3. tia 70 

og! W's) °F PC 295 | 74.8 0 0 AS 120 95 | 24.1 1.9 712 


1 Percentage of total trees (infected and sound) bearing injuries to total trees in stand = 70. 
§ Percentage taved gut totad nupaher wgeaea:r ARlETE 
Table V shows certain interesting results. On both types of site 
the infections traced to branch stubs bear the largest percentage 
over infections traced to other injuries, with 77 per cent for the 
bottom sites and 75 per cent for the slope sites. Broken tops as 
sources of original infection were not found, although a considerable 
number of broken-top trees were recorded and some of these trees 
gave evidence that a certain amount of infection took place through 


the exposed tip. In nearly every case it was found that infection ~ 


in the lower part of the trunk had taken place some time previous 
to the breakage of the top, as indicated by the difference in the stage 
of development of the two rotted areas. On the bottom sites ap- 
proximately 2 per cent of the infections were traced to frost cracks 
and 22 per cent to miscellaneous injuries, which latter included fire 


scars, blazes, windfall scars, etc. On the slope sites only 1 per cent 


of the infections were traced to frost cracks and 24 per cent to 


miscellaneous injuries. On the slope sites a larger percentage of — 


infection traced to miscellaneous injuries is found than is recorded 


THE ROTS OF WESTERN WHITE PINE. | 15 


for the bottom sites. This is due principally to the larger number of 
basal fire scars recorded for the trees on the slopes. On both types 
of site a steady increase of the total number of trees with injuries is 
recorded, ranging on the bottom sites from 0 in the 41 to 60 age class 
to 97 per cent in the 201+ class. On the slope sites the percentage 
ranges from 0 in the 41 to 60 age class to 99 per cent in the 201+ 
class. Comparing the entire stand of each type of site it is seen that 
the percentage of total trees infected is 55 on the bottom sites and 
55.8 on the slope sites. A more correct comparison of the amount of 
injury found in the stands of each type of site is made by con- 
trasting the percentages of total trees, both sound and infected, bear- 
ing injuries. For the bottom sites this percentage is 90 and for the 
slope sites 70, indicating that a larger number of trees on the bottom 
sites bore injuries. This difference may be partly due to the presence 
of a larger number of branch stubs on the trees of the bottom sites. 
These data clearly indicate the increasing danger of infection through 
injuries with the increase in age for both sites. 

From a study of Table V it appears that frost cracks as sources of 
infection are more common in the older age classes and not present 
at allin the younger. The recorded field data show that frost cracks 
were more frequent in the older trees, which accounts for the pre- 
_ ceding statement. 

The degree of injury for the two types of site shows a fairly steady 
increase with increased age and a slight difference in degree of injury 
for the total stand of the two types of site. The bottom sites have 
but a few tenths greater degree of injury. 

Table V shows that 10 to 30 per cent of the trees are without in- 
juries. ‘These trees are principally in the youngest age classes and 
bear no dead branches. 


SPOROPHORES. 


Most of the sporophores encountered in the western white-pine study 
were those of 7vametes pint. Very few sporophores of Polyporus 
schweimitzu or of Fomes annosus were found attached to the trees. 
Most of the Polyporus schweinitzii fruiting bodies developed on the 
ground at the base or near the host, and the logging operations 
nearly always disturbed these from their original positions. A very 
few sporophores of Polyporus schweiniizit were found attached di- 
rectly to the base of the tree. The data in Table VI, therefore, are 
principally from field notes on one fungus, Z7’rametes pint. In this 
table it will be noted that the 41 to 60 age class is omitted, since no 
rot and therefore no sporophores were present on the trees of this 
class. On the bottom sites out of a total of 533 trees approximately 
_ 380 per cent were found bearing sporophores. On these sporophore- 
_ bearing trees a total of 604 sporophores were recorded, of which 561, 


16 BULLETIN 799, U. S. DEPARTMENT OF AGRICULTURE. 


or practically 93 per cent (92.8), were alive and 438, or over 7 per 
cent (7.2), were dead, giving an average of 35 sporophores to every 
10 trees for the live sporophores, 8 to every 10 trees:for the dead 
sporophores, and an average of 38 sporophores both dead and alive — 
for every 10 trees. An average of 11 sporophores both dead and 
alive for every 10 trees is found when all the trees of the six age 
classes are considered. Of the largest sporophores, which varied in — 
size up to 6 by 6 by 8 inches, 92 per cent were found alive and 8 per 
cent dead. The average of the ages of the largest sporophores is 
approximately 15 years, and the average height on the trunk is 5.1 
feet. 


/ 


' 
Oe —— 


17 


THE ROTS OF WESTERN WHITE PINE. 


~ 


"$90.11 OT AIDA 04 GZ 
901} SUIIvOq-o104dol0ds 19g q 


*S0014 OT AIOAO 01 98 2 


°S0011 OT AIOAS 04 FE B *seroqdosods Jsosrv] Jo ose osvIOAY f *Se0T} OT AIOAO 04 8G a S001] OT £10A9 01 ¢ p 
*S001] OT AT9Ae 04 CE 9 


“gout [ Aq T Aq T Sem pojou st soloydoiods os1e] Jo sousseid OY} JOASIOYM PUNO; e10YdoIOds 4se][eUIS 944 JO OZIS OIL, v 


oy ae |< Se <o-=)~ ee AS See Sie aS “er ae IS =< oe “Wak Oc. 2 |" “SiIppiy jf =>" S5r- sae: sa” “OMT A saa 9°St | Sou | BEB [on Ro ong OB BIO 
6ST £°S P°9 0°9 Gm) abl Sin We Biel Lb icelc le at aS Sit eS ore. Sp as eee eae 8.9 [2 Se: Lame eae “*"e8eqUe0IEg 
#9 Gel yee | GE Te eo Tm ee: I 98 SOI" OPPHA jOTAqoTsqg| 8 | 98L| ET} 8° Teg] 98] 6h} HPT | 299 eet 
1R10L, 
¢ T T C By ee a ee eget op-- ot Aq oT Aq 9 3S L €°ZT | re" oZ 9 ST 6 02 “***"sreed +103 
Z 7 7 P 6 7 02 Cte) ee Lee op---|-9 4q 9 Aq F rd 1Z L°91 | 29° 29 Gg 1g &% 66 SIvet 00% 04 I9T 
ug 1Z 9% &Z 92 19 CF €6 |e8'e | -SIppr |-2 44 F Aq 9 ¥ TOT | PZT | €8°T Og GZ COF GOT | S&z “sreod Q9T 0} IZT 
wer a | eT I Sn ee OL LSS | "oy des FZ | moW0g |-¢ Aq Eg AGE 0 z 9°8 | ST < 31 p a ‘ Lo aeecmcd 
eeeeoe- =< -~-|ee@e ere sice Pere rleert were lee eee eel we we ee wwe lee ee eel we eel bie Ce id ed D ee o- 03 T 
Bee ee ES Ph Ee Sal” “See es San cia cae ey eee ee | eee ed er Be he ees aS a SN ee ee ae 0 0 0 0 0 09 --"sivod 08 04 19 
:soyzIs edorg 
ae eee | eee ee | eee ee SASOINAS aS lee | ket omar | eS Ses Ig -=#" "qo, ie ie ae | ee oe "ITV Tcts ‘ie 8°Ea LZ °P Ca SF Lge Same | Han ce (ge q OSBIOAY 
8°L ¢°¢e bP Fi OBC ek Gi IRL CT C. es0le | Se ee ee Soe EEE meek Cae eke Ge ae | eet GL 8'26 BB Ca aS <a th 938} 00010 g 
| OLT &% CF SPI POT £9 °° ial ial heat ibe “doz, |-s 4q4 9 4q 9 €I OFT | I'ST] IT £09 eh 19S 6ST | Es or pe ih . 
0 0 0 0 8 8 0 Os Sees op’-"|"9 AQF AGT] O 6 08% | 9F° st 0 8I 6 68 “--*"sIvek +10 
oT z 0 0 cT I eT 0 £9 |°""""op--"|-g Aq 9g Aq F T 02 9°6T | $L° 9g 6 Lt 1 9L “sIe0A 00Z 03 TOT 
Gs 8 II #E €¢ 1g 0g CG) | Gh ota op--*|"g Aq 9 Aq 9 L 6F G8] 2% £62 0z E12 9¢ 621 “sievod O9T 04 IZT 
G p L OT GF r1 6 Siz) Os oh dog, |"¥¢ Aq g Aqe 7 oP eel | FT 9ST II CFT OF IIT “sIeo0A 0ZT 04 TOT 
v g g T &Z IT Ot €l | 8°T | -°MPIA |S 4q g Aq F I 7 ¢°¢ | €9° PL g i G QIT ““s1v0A QOT 04 18 
0 0 0 0 7 T Z 0 80 | moyW0g |-7 4q 2 AQT 0 Z o’¢ | ITO L 0 l z 29 ~**siv0A 08 03 19 
"JOT *Sayoury *SL00X - S0}JS 010940. 
be qn “peo| ‘eary ge | on 
“4sem | *4Se0 | “4sem | -4Se0 |. 4 , f uoje : ‘ese | JO . 
-aanog | yanog |-q20N -qyz0N] “*S°AL | “3S€SL [UNOS [AON UBIO uornsod | "S971 -roay | age | Te}0L| Peed | “eat | ‘sozogd j n 
OATIRIO ~IOAV “01048 |. (sigeq) : 
“OAV *MOTIIpUoD sur gama 
-80q | Gon “ssel0 Os y 
seer, | $9204 
-manN 
“0014 O44 UO MOT}ISOd ove IO} IEQUINN “4S03I0'T *IequUInN ai at 


a a EE ee 
 *sezoydorodg 
a ee ee ee 
‘sodfg adojs pup wo0z20q ay42 Jo says uo oud ayy Usaysom UO sasoydosods 02 6u4zpja4 sazou pjey fo isanwung—tIA aTav TL, 


a + n = "> 


18 BULLETIN 799, U. S. DEPARTMENT OF AGRICULTURE. ~ 


In classifying the sporophores according to the positions occu- 
pied on the trunk of the host it was found that the largest percentage 
of them (28 per cent) developed on the west side of the tree, with 
the smallest percentage (3.3) on the southeast side. Most of the 
largest ones were found near the upper end of the group on each tree. 
On the slope sites, out of a total of 662 trees 22 per cent were 
found bearing sporophores. In this connection it must be remem- 
bered that a much higher percentage of the trees on the slope sites 
was in the 120 to 160 age class, which bore the maximum number of > 
sporophores. The sporophore-bearing trees carried a total of 531 
sporophores both dead and alive, of which 495, or over 93 per cent 
(93.2), were alive and 36, or nearly 7 per cent (6.8), were dead. 
These figures give an average for the total stand of 34 live sporo- 
phores to every 10 trees, 2.5 dead sporophores to every 10 trees, and 
36 live and dead sporophores to every 10 trees. Considering all of © 
the trees of the six age classes given and not limiting the figures to — 
sporophore-bearing trees alone, an average of eight sporophores both ~ 
dead and alive was found for every 10 trees. Of the largest sporo- — 
phores, which varied in size from 1 by 1 by 1 to 6 by 10 by 10 inches, © 
94 per cent were found alive and 6 per cent dead. The average of the © 
ages of the largest sporophores is recorded as approximately 12 © 
years and the average height on the trunk was 5.5 feet. Most of the © 
sporophores on this site were found grouped on the north side of the © 
trunks, 21 per cent being on the north side and the smallest, or 5 per — 
cent, on the southeast side. Most of the largest ones were found at 
about the middle of each group of sporophores. 

In comparing the two types of site some interesting figures are ~ 
disclosed. The bottom sites, to begin with, have a larger percentage — 
of sporophore-bearing trees and a slightly larger average number © 
both of living and of dead sporophores per sporophore-bearing tree. 
In the 81 to 100 age class the bottom sites have 22 per cent of the 
total trees bearing sporophores, while for the slope site there are 
none. In the 101 to 120 age class on the bottom sites 41 per cent of © 
the total trees were found bearing sporophores, with only 7 per cent 
in the slope sites. In the 121 to 160 age class are found the maximum ~ 
figures. In this age class for the bottom sites 43 per cent of the total 
trees bore sporophores and for the slope sites 45 per cent. The aver- 
age of the ages of the largest sporophores is also greater on these sites. 
On the other hand, the slope sites have a greater percentage of the 
larger sporophores alive than the bottom sites. It is very interesting 
to find that the percentage of live and dead sporophores to the total 
number of sporophores is practically the same for both types of 
site. This would seem to indicate that site does not appreciably © 
affect the vitality of the sporophore, although it apparently affects — 
the number of sporophores produced. 


THE ROTS OF WESTERN WHITE PINE. 19 


On the bottom sites it is observed that sporophores are recorded for 
all the age classes, including that of 61 to 80 years. In the slope sites 
both the 61 to 80 and the 81 to 100 age classes have no sporophores 
_ fecorded. The first sporophores appear in the 101 to 120 age class. 
They increase in number in the 121 to 160 age class and decline in the 
161 to 200 and the 201+ age classes. The column indicating the 
average number of sporophores per tree indicates this very clearly. 
_ The column recording the number of sporophore-bearing trees shows 
a similar increase, reaching a maximum in the 121 to 160 age class, 
-and a rapid decline is noted in the two succeeding age classes. These 
data indicate a maximum of sporophore production attained in 
the 121 to 160 age class and show the rapidly decreasing numbers of ~ 
sporophores present on the trees of the two oldest age classes. Two 
factors are responsible for the decline—first, the fact that the fungus 
in the tree has reached and passed its maximum development and so 
produced fewer new sporophores, and second, the fact that in the 
old-age classes the old sporophores are observed to have died, be- 
come loosened from the trunk, and dropped off. The relation of rot 
percentage to sporophores is evident when compared on a basis of 
site: On the bottom sites the rot percentage is nearly 8 (7.8, Table 1), 
and an average of 1.1 sporophore per tree or 11 sporophores to every 
_ 10 trees is recorded. In the slope site the rot percentage is over 6 
_ (6.1, Table I), and the average number of sporophores per tree is 
0.8 or 8 sporophores to every 10 trees. The bottom sites show a 
greater rot percentage and a greater average number of sporophores 
per tree. 

Another interesting point brought out by the table is the fact that 
on both types of site the smallest groupings of sporophores were 
found on the southeast side of the trees. 


DISCUSSION OF RESULTS. 


From the foregoing data it appears that age is the important factor 
_ in determining the amount of rot to be expected in a western white- 
pine stand. This factor of age is significant in the application of | 
proper silvicultural methods to the care and disposal of the timber. 
From the forester’s point of view two things stand out in consider- 
ing the stand in relation to rots. The one is the age of earliest infec- 
tion of the stand, or the period when infection by fungi can first be 
_ expected. This is undoubtedly controlled by the formation of heart- 
_ wood and the appearance of injuries susceptible to infection. This 
Infection age is found to be approximately 50 years for western white 
_ pine, and it indicates the period when the young stand is in need of 
the utmost protection against infection by fungous spores. Infection 
_ takes place in this tree earlier than at 50 years in certain individuals, 


20 . BULLETIN 799, U. S. DEPARTMENT OF AGRICULTURE. 


and, of course, infection continues to take place in all stands after the — 
50-year period is reached, and no doubt at an increased rate. 

The other consideration of importance to the forester is the period 
in the age of the stand at which the net increment of sound material 
passes its maximum. This period is more or less indefinite and diffi- 
cult to express in actual age figures. It depends primarily upon 
_ what the forester considers the dividing line between a stand haying ~ 
sufficient sound material to pay a profit for logging and one having ~ 
so much rot that logging would not be profitable or the profit a small — 
one, all factors considered. From the viewpoint of annual inecre- | 
ment the forester has determined that a rotation of 100 to 120 years 
for western white pine gives a maximum yield.’ If this holds true, 
then it also appears that this will mean the cutting of the stand when 
the average rot percentage for the bottom sites is 1.7 and for the 
slope sites 0.5. Glancing at Table I it is seen that for both types 
of site an appreciable increase in the average annual increase in | 
rot volume is recorded between the 101 to 120 and the 121 to 160 ~ 
age classes. i 

In the sporophore summaries (Table VI) an apparent maximum | 
point is reached in the 121 to 160 age class in respect to the number 4 
of sporophore-bearing trees and to the number of sporphores pro- — 
duced. The 101 to 120 age class would, therefore, represent the age 
class having, on the average, a stage of development of the rot below 
the maximum stage for sporophore production. These facts point 
to the 101 to 120 age class as a possible felling age from the patho- 
logical point of view, and it remains to discover whether an average 
rot percentage of 1.7 on the bottom sites and 0.5 per cent in the slope ~ 
sites conforms to the most economical logging or whether a higher ~ 
rot or cull percentage is possible without a sacrifice in the returns — 
on the operation. The next higher age class (121 to 160) records © 
a rot percentage of 3.1 for the bottom sites and 2.3 for the slope sites. — 

In the relation of age to injuries the data have shown that with 
increased age comes a greater degree of injury. This is evident for 
both types of site in all the age classes excepting the 161 to 200, © 
which drops slightly below the preceding age class in degree of in- — 
jury. It is so well understood that increased age brings cumulative ~ 
risks of greater injury that a discussion seems unnecessary. : 

A steady increase in the number of trees with injuries to which | 
infection was traced is noted with increase in age for hoeR the bot- | 
tom and slope types of site. é 

It is readily seen that age up to a certain limit has a definite re- 


lation to the sporophore production of a stand. If rot increases with | 


*Mason, D. T. Management of western white pine. Jn Proc. Soc. Amer. Foresters, 
ve 9, mo.. 1; p,-64,5. .2014. 


THE ROTS OF WESTERN WHITE PINE. SE 


age, then it follows that the production of sporophores will also in- 
- erease as the decay develops to that stage where fruiting bodies 
are produced. It is also to be expected that when the period of 
“maximum sporophore production is passed there will be a gradual 
decline in- the numbers produced and also in the numbers retained 
upon the trunk. Fewer new sporophores are produced in the old- 
aged trees of the stand, and of the old sporophores already on the 
tree many die, become loosened from the trunk, and drop off. The 
data show for both types of site that there is an increase in the 
number of trees bearing sporophores and in the average number of 
sporophores per tree, from the 61 to 80 to the 121 to 160 age classes, 
inclusive, while a decrease is noted for the 161 to 200 and the 201 
age classes. This indicates a maximum sporophore production in 
the 121 to 160. age class and a declining production. for the age 
classes following. 

Figures have been given which show that site plays an important 
part in the development of rot in a stand. The consensus of opinion 
~ among practical loggers is that low, flat, and poorly drained sites 
bear stands having the greatest amount of rot and that the sites 

where trees are freest from rot or where the rot percentage is small 

are well-drained slopes or benches. The comparison of slope and 
bottom sites in respect to rot percentage, both for age classes and 
for the total stand, indicates that a greater amount of rot is preva- 
lent on the bottom sites. A comparison between trees taken from 
similar sites upon widely separated areas and having a difference 
mm average age of 10 years shows a difference of 1 per cent in rot be- 
tween these two areas. The percentage is greater on the area having 
the greater average age. The same indication is given by the figures 
for the percentage of infected trees. These data also furnish evi- 
dence of the influence of age upon the amount of rot to be found 
in a stand. Further comparisons of trees occurring on slope and 
bottom sites on the same sale areas also indicate that the trees on 
the bottom sites bear a greater percentage of rot than those on the | 
slopes. 

In respect to the influence of site upon degree of injury the data 
do not show conclusively that a greater degree of injury exists upon 
_ bottom sites. The bottom sites with 2.4 and the slope sites with 1.9 
(Table V) leave too small a difference to attribute them to the in- 
fluence of site. Apparently greater percentages of infections are 
_ traced to branch stubs on the bottom sites than on the slopes. This 
may be due to the formation of a larger number of. dead branches 
on the bottom sites as a result of greater shade. Light more easily 
_ reaches the lower branches of trees growing on a slope than of trees 
growing on the bottom sites, providing the densities are about equal. 
This might be a possible explanation of the formation of a greater 


22 BULLETIN 799, U. S. DEPARTMENT OF AGRICULTURE. 


. number of dead branches on trees of the bottom sites. Site is ap- 
parently responsible for a greater percentage of sporophores de- 
veloping on the trees of the bottom sites. An average for the bot-— 
tom sites gives a distribution of 11 sporophores to every 10 trees, 
while the slope sites have 8 sporophores to every 10 trees. The pro- 
portion of live and dead sporophores to the total sporophores is 
about equal on each type of site, 93 per cent alive and 7 per cent 
dead. The proportion of live and dead sporophores to the total, in 
the case of the largest sporophores, shows a percentage approaching 
that already given, also showing very little variation in respect to — 
site. A greater number of sporophore-bearing trees are found upon 
the bottom sites. | 
METHODS OF CONTROL. 


From the study of the data presented, it appears that the control — 
of diseases in western white pine under the present stage of forestry — 
in the Northwestern States will be a difficult matter and subject to 
extensive rather than intensive methods. The high economic value — 
of the tree and the large amount of loss due to rot are two important — 
factors which make it imperative that steps be taken at least to 
check the diseases and that attempts be made to reduce the annual © 
loss of sound material brought about by the spread of the casual — 
organisms. 

There are two methods of control which present themselves as 
practicable under the present methods of forest management. These 
two methods work hand in hand. The first method is primarily — 
based upon the rotation of the stand or the felling age. It is evident — 
from a study of the data presented that if the stand is cut before any — 
sporophores are produced, or before they are produced in any great 
numbers, the spread of the diseases will be effectively checked. The ~ 
data show that a certain age class represents the period in the stand 
which develops a maximum of sporophores. This period in western’ 
white pine is represented by the 121 to 160 age class. This age 
class has 43 per cent of the total trees bearing sporophores for the 
bottom sites and 45 per cent for the slope sites. Both the next lower 
and the next higher age classes have smaller percentages for the two 
types of site than the 121 to 160 age class. If the felling age of west- 
ern white pine is kept within the 101 to 120 age class there is every 
reason to believe that the infected trees will be cut down before they 
reach the age of maximum sporophore production. Most of them 
will no doubt be cut down before any fruiting bodies whatever 
appear. This is the most desirable result and is particularly true 
for the slope sites. a 

The second method is fundamentally concerned in the strict apphi- 
cation of proper pathological marking rules and the consequent re- — 


THE ROTS OF WESTERN WHITE PINE. | 23 


moval of all infected slash on the sale areas. The marking rules 
should provide definite instructions to fit each distinct sale area and 
should include the consideration of the classification of stands in 
the western white-pine type and the methods of cutting employed on 
each. The pathological marking rules should specify the cutting of 
all diseased trees on a sale area where selection cutting is employed 
and the retention on clean-cut areas of seed trees free from all root, 
butt, and trunk rots, as well as from rust and mistletoe. These two 
recommendations will insure a healthier second growth in the case 
of selection or improvement cuttings, and in the case of clean-cut 
areas will insure the reserved seed trees against windfall and wind- 
break due to fungous activity.t. In the case of the clean-cut area 
the retention of sound seed trees will also prevent distribution of 
diseases by these trees. If seed trees other than western white pine 
are reserved, the selection of sound trees will prevent infection of 
young growth by the rust? and mistletoe* diseases which are pe- 
culiar to certain tree species, such as Engelmann spruce and western 
larch, found in stands of the western white-pine type. The removal 
of all infected slash left on a sale area after logging is an important 
part of the successful control of fungous diseases. In order to pre- 
vent the spread of the diseases which have caused rot in the trees of 
the stand all infected slash liable to develop sporophores should be 
disposed of in such a manner as to check the development’ of the 
fungus and thus prevent subsequent sporophore production, or it 
should be destroyed outright in some manner consistent with eco- 
nomic requirements. 


SUMMARY. 


_ Data obtained in a study of the rots of western white pine show 
the following conclusions as presented in this bulletin: 

The three main wood-destroying fungi in the order of their im- 
portance are Z'rametes pini, Polyporus schweinitzii, and Fomes an- 
mosus. Most of the rot found in the tree is traceable to 7. pini. 

Trametes pini attacks all portions of the trunk, acting in some 
cases as a typical butt-rot. Polyporus schweinitzii is found to pro- 
duce a typical butt-rot, and Fomes annosus is chiefly confined to the 
roots and butt of the tree. 


1 Hubert, HE. E. Fungi as contributory causes of windfall in the Northwest. Jn Jour. 
Forestry, v. 16, no. 6, pp. 696-714. 1918. Bibliography, pp. 713-714. 

2 Weir, J. R., and Hubert, HE. H. Notes on forest-tree rusts. In Phytopathology, v. 8, 
no. 3, pp. 114-118. 1918. 

Notes on the overwintering of forest-tree rusts. In Phytopathology, 
v. 8, no. 2, pp. 55-59. 1918. 

8 Weir, J. R. Larch mistletoe: Some economic considerations of its injurous effects. 
U. 8S. Dept. Agr. Bul. 317, 25 p. 1916. 
Some suggestions on the control of mistletoe in the national forests of the 
Northwest. Jn Forestry Quart., v. 14, no. 4, pp. 567-577. 1916. 


24 BULLETIN 799, U. 8S. DEPARTMENT OF AGRICULTURE. 


It is found that an average rot percentage of 7 represents the 


proportion of sound wood rotted by these agencies in the stands of | 


timber classified under the western white-pine type. This represents 


a loss of $7,201,250, or 1,658 million feet B. M., in the forests of q 


British Columbia, Oregon, Washington, Idaho, and Montana. 


The data indicate that the factor of age is prominent in deter- a 


mining the amount and stage of decay in a stand. The age of 


earliest infection was found to be approximately 50 years for the 4 


trees in general for the Coeur d’Alene region of Idaho. 


Site is found to have a bearing upon the rot in the stand. The_ 
bottom site, in general, is found to be more favorable to the devel- — 


opment of fungous diseases. Site, apparently, has no great effect 
upon the percentage of trees infected, both sites showing approxi- 
mately the same percentage. A larger percentage of the slope trees 
were in the heavier infected age classes. This was not the case for 
the bottom sites, and therefore a direct comparison of the total 
percentage of trees infected gives figures which are higher for the 
slope sites than would otherwise be true. In general, a greater rot 
percentage, a greater percentage of infected trees, a greater amount 
of butt-rot, a greater degree of injury, and a larger average num- 
ber of sporophores per tree are recorded for the bottom sites than 


for the slopes. This indicates that the bottom sites are more favor- — 


able to the development of fungous diseases. 

With increased age up to a certain point comes an increase in the 
number of sporophore- bearing trees and an increase in the ae 
of injury. 


The maximum production of sporophores is found to occur in the 
121 to 160 age class. The 101 to 120 age class presents, in so far as © 
the rot data show, favorable figures upon which to determine a — 


pathological felling age. 


The high economic value of the tree coupled with the large amount ‘ 


of loss annually sustained through heart-rotting fungi makes it 
highly necessary to attempt control methods. 


The loss due to rots may be reduced by the application of control | 


methods aiming to prevent the spread of the organisms bg mi 2 
decay. 


Proper pathological marking rules and practical methods for the 
disposal of infected slash on sale areas are recommended as methods — 


of control. 


ADDITIONAL COPIES 
OF THIS PUBLICATION MAY BE PROCURED FROM 
THE SUPERINTENDENT OF DOCUMENTS © 
GOVERNMENT PRINTING OFFICE 
WASHINGTON, D.C. 
AT 


5 CENTS PER COPY 
vy ; 


“ 
: —— 
= ss on 


i 
4 


UNITED STATES DEPARTMENT OF AGRICULTURE 


BULLETIN No. 871 


Contribution from the Bureau of Plant Industry 
WM. A. TAYLOR, Chief 


Washington, D. C. PROFESSIONAL PAPER November 10, 1920 


THE DRY-ROT OF INCENSE CEDAR. 


By J. S. Boyce, Assistant Pathologist, O fice of Investigations in Forest Pathology. 


CONTENTS. 

Page. Page. 
Importance of incense cedar.............-.-- Ly |}; AC DPMCALION OL TESUMUS. acc asio6 a-\re- Se oc nee 49 
Camis 1BCLOMS ss bi). Se eee 2 Relative importance of dry-rot.........-- 49 
Method of collecting data.......-.. a Se 4 Control of GEy-FOb ses seweess opekan me  sacxde 49 
0 Sy ee Ce IAPOMR RR Yo arsine che oi dare ie wiane emia eye S asain Ao iw 55 
oe eee Sp Eerperacere Cited. hil. cree ei Ra 57 


IMPORTANCE OF INCENSE CEDAR. 


Incense cedar (Libocedrus decurrens) is of considerable economic 
importance on the Pacific coast. The available supply of this species, 
which never occurs alone but always in mixture, chiefly with yellow 
pine, Jeffrey pine, sugar pine, Douglas fir, and white fir, averaging 
about 8 per cent of the stand, although often forming as high as 30 
to 50 per cent, is estimated at 11 billion feet, 10 billion of which 
occurs in California (17, pp. 9-10).. That the wood is very valuable 
for special purposes on account of certain qualities has been clearly 
pointed out by Mitchell (17, pp. 2-9) recently and was mentioned by 
Von Schrenk (26, p. 69) 20 years ago. However, in spite of the well- 
known value of the wood, only about 30 million feet is cut annually 
in California. The stumpage rate is low and the price for the finished 
product often little more than pays the cost of logging and manufac- 
ture, according to Mitchell (17, p. 6). 

The reason for this is obvious. The heartwood of incense cedar is 
commonly rendered totally worthless by the so-called dry-rot caused 

by Polyporus amarus. An idea of the quantity of timber rendered 
unmerchantable by this dry-rot may be obtained from Mitchell’s 
statement (17, p. 3) that so common is this defect that it is the usual 
practice to cut estimates of this species from 30 to 50 per cent on ac- 


1 The serial numbers in parentheses refer to “‘ Literature cited” at the end of the bulletin. 
182803°—20—Bull. 871——1 


2 BULLETIN 871, U. S. DEPARTMENT OF AGRICULTURE. 


count of it. This leads to a distinct prejudice against the species 


on the part of both the lumberman and the forester. The lumber- 
man is naturally averse to handling a large quantity of practically © 
worthless material for which there is little or no market in order to 


secure a small amount of valuable material, when the profit on the 
more valuable product is not sufficient to carry adequately the entire 
product. The forester sees a species of very little value, as attested 
by the low stumpage rate, occupying space which might be given 
over to surrounding species on which a much higher stunts rate 
could be realized. 

This prejudice, which has resulted in the classification of incense 
cedar as an ‘‘inferior” species, is not based on any inherent quality 
of the tree itself, for sound cedar wood, as has already been stated, 
is quite valuable, finding a ready market; and the tree, on account of 
its relatively high tolerance of shade, particularly during its earlier 
life, is a valuable component of the mixed stand in which it occurs. 

Incense cedar is a thrifty, aggressive species, quite tolerant of shade, 
and has a definite, permanent place in the forests of the Pacific coast. 
Its aggressiveness makes it almost an impossibility to eradicate the 
species entirely, and such an attempt would be highly inadvisable 
and might result in unforeseen disastrous consequences resulting 
from an artificial change in the composition of the stand. Greeley 


(6, p. 112) and Meinecke (16, pp. 21-22) have specifically advised © 


against this. The lumberman, logging in types with incense cedar 
represented, faces the necessity of handling a large quantity of almost 
worthless timber, which if sound would be of high value. 

Since incense cedar probably can not be eliminated from the stand, 
the problem presents itself of the proper treatment of an inferior 
species which in time will undoubtedly become quite valuable. 
Foresters and lumbermen are showing more and more interest in the 
question, fully realizing that this species will always have to be 
reckoned with. We must have exact, far-reaching studies not only 
to handle properly and utilize the cedar at present, but to lay the foun- 
dations for a rational system of silvicultural management for the 
future. Production is inevitable; proper treatment must be evolved. 
Consequently, the study on which this paper is based was under- 
taken in an attempt to throw light on certain of the phases involved. 


TOTAL-LOSS FACTORS. 


Throughout American forestry literature dealing with regulation 
and management are found statements in regard to individual com- 
ponents of mixed stands to the effect that ‘in virgin forests incre- 


ment equals decay,” or sometimes “deterioration” is used in place 


of ‘“decay.”” Chapman (2, p. 317) and Meinecke (16, p. 3-4) have 


waa ae” se Ue RY 


eg ee & 


* —_ 


shown this generalization to be of absolutely no value, since the as- 


DRY-ROT OF INCENSE CEDAR. 3 


sumption is based on the factors of increment and decay, of which 
almost nothing is known. When deterioration is used in place of 
decay, it is an impossibility to reach a conclusion as to just what 
factors of loss are included in the term. 

The term “total loss’’ has been introduced by Meinecke (16, p. 4-5) 
to cover all factors which lead to any reduction of increment or 
actual volume in a stand, and he makes a strong plea for exact studies 
of all components of the total-loss factor for individual species before 
any effort is made to determine this for the mixed stand. 

To determine the components of the total-loss factor for any given 
species is merely a matter of simple observation, but to gauge accu- 
rately their relative importance is not easy, calling for careful com- 
prehensive work. 

In the case of incense cedar the numerical dropping out of indi- 
vidual trees, the mechanical injuries caused by fire, frost, light- 
ning, the breaking of branches, and other causes, a mistletoe, and 
several fungi play a more or less important part in the total-loss 
factor. These components may be divided into two broad classes, 
those reducing the future capital of timber (lessening the increment) 
and those reducing the present capital of timber (destroying actual 
merchantable material). It is impossible to draw a sharp line 
between these two classes, since some components find a place in 
both. 

The unavoidable yearly dropping out of certain trees, varying in 
size from seedlings to veterans, affects both the increment and mer- 
chantable material in a stand. Mechanical injuries, while primarily 
causing a loss in the merchantable timber, to some extent interfere 
with the normal growth of the tree, thus reducing the increment. 

A mistletoe (Phoradendron juniperinum libocedri), the incense-cedar 
rust (Gymnosporangium blasdaleanum) (15, p. 35-37; 11), a leaf-in- 
habiting fungus (Stigmatea sequoiae) (3, p. 87; 4, p. 314), and the black 
cobweb fungus (Herpotrichia nigra) all primarily cause a loss in the 
future capital of timber by reducing the annual increment of infected 
trees. The amount of this loss is exceedingly difficult to gauge 
accurately, but it is so small in relation to the damage caused by 
the agencies reducing the present capital of timber that the above- 
mentioned organisms are given no consideration in this paper except 
incidental mention. Under certain conditions, the mistletoe is 
responsible for a slight reduction in the merchantable contents of 
the host tree by causing spindle to barrel shaped swellings on the 
boles of mature and overmature trees (14, p. 37). The wood of 
these swellings is rendered valueless for lumber, owing to the pres- 
ence of the mistletoe ‘‘sinkers,’’ or roots, either living or dead. 
Swellings are rarely, if ever, found on the boles of younger trees. 


4 BULLETIN 871, U. S. DEPARTMENT OF AGRICULTURE. 


Most important of all, however, is the loss of the present capital 
of timber through ne The organisms causing decay in incense 
cedar are the pouch fungus (Polyporus volvatus), Polystictus abietinus, 
Polystictus versicolor, Lenzites sepiaria, the red-belt Fomes (Fomes — 
pinicola), some unknown fungi, and the incense-cedar dry-rot fungus © 
(Polyporus amarus). The first five listed have never been found 
attacking living incense cedars. There are several forms of decay 
of trifling importance in living treés, the causes of which have not 
been determined. Polyporus schweinitzii has been found in one case. 

Standing out above all the other components of the total-loss— 
factor is Polyporus amarus, causing dry-rot in the heartwood of the 
tree. Since the first utilization of incense cedar, the great destruc- 
tion wrought by this fungus has been a matter of extreme concern 
to lumbermen and foresters, as is shown by the constant references — 
to the decay found throughout the literature wherever incense cedar — 
is mentioned. 

The importance of dry-rot can not be overestimated, and it is on 
this point, together with the related mechanical injuries, that a study 
of the total- Wess factor must be concentrated; the gos considera- 
tions play a distinctly secondary rdle. 


METHOD OF COLLECTING DATA. 
SELECTION OF AREAS. 


The first step in carrying on a study of the total-loss factors in 
any given species is the selection of proper areas for work. The 
areas selected, if the results are to serve for any but strictly local 
application, must be representative of the larger unit or region of 
which they form a part. It is self-evident then that areas located 
in the altitudinal or horizontal extremes of the range of the species 
under investigation must be avoided. The results of a study on 
such areas, while scientifically interesting, would be absolutely with- 
out practical value, since they would only answer for a limited unit — 
on which the stand is abnormal and would fail to answer any ques- 
tions in regard to the major and more valuable portion of the range 
of the species. 

All indications tend to show that there is a considerable variation 
in the growth and development of incense cedar in different parts 
of its range. This has already been hinted at by Mitchell (17, p. 9, 
13, 23, 24). The writer distinguishes three distinct ranges based 
on the development of the tree, and these are termed, for conve- — 
nience, the optimum, intermediate, and extreme ranges. | 

The best development is found in the southern Sierras, particularly 
on the Sierra, Sequoia, and Stanislaus National Forests, and the 
southern portion of the Eldorado National Forest, where the species 
is relatively rapid growing and thrifty. 


-DRY-ROT OF INCENSE CEDAR. 5 


In the intermediate range, comprising the northern Sierras and 
the Coast Ranges, slower growth is the rule, and in the mixed stand 
where the cedar always occurs it plays a distinctly secondary part 
and might almost be classed as an understory tree. 

The poorest development is found in the extreme range, which 
includes stands at the horizontal and altitudinal extremes of the dis- 
tribution of the species. In such situations the trees are short, 
scrubby, and relatively of little value. 

With the above facts in mind, it was considered essential to choose 
areas representative of the intermediate and optimum range; the 
extreme range could be neglected, since it is of no practical im- 
portance. 

In the uneven-aged stands care had to be observed to select areas 
on which all age classes were represented, since if there is a relation 
between any of the total-loss factors and age of the tree, this would 
fail to appear if even-aged or nearly even-aged trees alone were con- 
sidered. 

Observation and a preliminary study by Memecke! showed con- 
clusively that the total-loss factor of supreme importance in the 
case of incense cedar is dry-rot caused by Polyporus amarus. Above 
all, then, it was essential to select stands in which dry-rot was com- 
mon, using discretion not to make the selections where loss from 
dry-rot was far above or below normal. Other total-loss factors, 
particularly mechanical injuries, could not be disregarded and were 
carefully considered. 

With a knowledge of the habits and condition of incense cedar 
throughout its range, several possible areas were tentatively chosen, 
a careful examination made in each case, and then the most suitable 
stands were decided upon. 


DESCRIPTION OF AREAS. 


The area selected to represent the intermediate range is at Sloat, 
Calif., within the boundaries of the Plumas National Forest, in the 
northern Sierra Nevada Mountains. In general, the region is one of 
heavy snowfall, with moderate winter temperatures and a long, 
dry, warm summer season. Lightning storms are not very frequent. 

The tract has a relative altitude of 4,300 to 4,700 feet. The fairly 
deep soil is a decomposed lava, normally dry and loose. 

The virgin uneven-aged stand, with a strong representation of 
mature and badly overmature trees of all species, is principally 
composed of western yellow pine (Pinus ponderosa), Jeffrey pine 
(Pmus jeffreyr), and Douglas fir (Pseudotsuga taxifolia). Where 

_1The writer wishes to acknowledge his indebtedness to Dr. E. P. Meinecke, who first inaugurated astudy 
of incense cedar in 1912, the data obtained being included in this paper, for advice and direction through- 


out the course of allthe later work. The essential methods followed in this study are outlined by him in 
United States Department of Agriculture Bulletin 275 (16). 


6 BULLETIN 871, U. S. DEPARTMENT OF AGRICULTURE. 


Douglas fir predominates, the two pines take second place, and vice 


versa. Third in order comes incense cedar, while sugar pine (Pinus 
lambertiana) and white fir (Abies concolor) are but lightly represented. 

In the more dense stand on the lower slopes and in the draws 
incense cedar forms a distinct understory, overtopped by all the other 
species; it is in such localities that the cedar shows every indication 
of slow growth and strong suppression. On the higher slopes and 
along the ridges, where the stand is more open, the cedar in individual 
cases often assumes a better position in the stand, and all the trees of 
this species, with few exceptions, appear to be more thrifty and to 
have made a more rapid growth. Badly suppressed trees are rare. 

The three areas selected to represent the optimum range are on 
the Stanislaus National Forest in the southern Sierra Nevada Moun- 
tains. One of these is at Strawberry, at an altitude of 5,300 to 5,600 
feet; a second at Cow Creek, about 5 miles north and east of the 
first and at about the same elevation; and the third at Crockers 
Station, about 30 miles to the south and a little east of the Straw- 
berry area and at an altitude of about 4,500 feet. Since the areas 
are so nearly alike, a composite description will suffice. 

The soil is a rather deep, loose, decomposed granite, with many 
large granite bowlders. It is normally somewhat dry. 
' The virgin uneven-aged overmature stand is rather open and is 
composed of sugar pine, western yellow pine, Jeffrey pine, white fir, 
incense cedar, and Douglas fir. Normally the pines predominate, 
with white fir or incense cedar next in order, Douglas fir being found 
sparingly only on the Crocker area. Incense cedar is represented 
by trees of all ages, and on the whole appears very thrifty. There 
are many individuals of large size, comparatively young. The cedar 
here is far from forming such a distinct understory as on the Sloat 
area, so the stand has made a much more rapid growth. 


NOTES ON INDIVIDUAL TREES. 


After the general notes were completed on an area, work was 
commenced on individual trees. ‘Trees of all ages and conditions 
must be cut for a study of this kind, the primary purpose being to 
determine the age of the stand at which dry-rot becomes extensive. 
Observations on logging operations and the results of Meinecke’s 
preliminary study had shown that trees between 100 and 240 years 
old would yield the essential data on this point, and it was within 
these age limits that the investigation was concentrated, but the 
lower and higher ages were not neglected by any means. ‘This 
resulted in clear cutting within the ages mentioned, except that those 
trees in which it was plainly apparent an accurate age count could 
not be made were left standing, while only a portion of the trees in 
the stand above and below these ages were cut. Thus, since a given 


| 
F 
| 
" 
} 
; 


ee ee oe en ee ee 


ee ee ee 


DRY-ROT OF INCENSE CEDAR. 7 


tract was not clear cut, the representation of age, diameter breast 
high, and height classes obtained from the study must not be assumed 
as an exact expression of the actual conditions. 

Each tree was cut as closely as possible to a stump height of 18 
inches, then limbed and bucked. The first or butt log was made 
7 feet long and the others 14 feet long, the number of cuts depending, 
of course, on the length of the tree. The last cut was always made 
well in the top near the upper limit of the heartwood. The reason 
for bucking in 7 and 14 foot lengths was purely a practical one; any 
sound heartwood could then be utilized for 7-foot posts. The age 
count at stump height was taken as the age of the tree instead of 
adding a few years corresponding to the height of the stump, since 
the aim is to have all figures taken directly comparable. In this 
case with a minute constant variation no error can be introduced. 
Trees with wounds which destroy the center at stump height were 
avoided when possible, since in such cases an accurate age count 
could not be obtained; hence, trees of this kind are valueless for all 
further calculations in which the exact ageis afactor. The sap width 
was obtained from an average of six or eight measurements. Three 
radii were measured to secure the average diameter. Separate 
measurements were made for the area covered by decay. The dates 
of occurrence and closure, when healed, were determined for all 
wounds present. Each log was split at least once in order to reveal 
completely all decay and internal wounds. Great care had to be 
observed in splitting the logs in order to be certain not to miss any 
decay, since the dry-rot occurs in pockets which may be separated 
in a linear direction by several feet of sound wood. ‘This habit of 
‘“jumping”’ also made it exceedingly difficult to trace the entrance 
of the decay in certain cases where the decay might be several feet 
removed from any possible point of entrance. It often became 
necessary to split log after Jog into many small pieces. 

In all, 1,075 trees were analyzed, 509 at Sloat, 266 at Strawberry, 
100 at Cow Creek, and 200 at Crockers Station. 

In all future references i in this paper, for the sake of convenience 
the term ‘‘intermediate area’’ will be used to designate the area at 
Sloat, since it represents conditions in the intermediate range, and 
the term ‘‘optimum area”’ to designate the combined areas at Straw- 
berry, Cow Creek, and Crockers Station, since they represent condi- 
tions in the optimum range. The results of the field work follow. 


SECONDARY ROTS. 


Under this heading are grouped all decays the causes of which 
are unknown. Such decays are of various types and are almost 
invariably found immediately adjacent to open or healed-over 
wounds, particularly fire scars. Instances were encountered where 


8 BULLETIN 871, U. S. DEPARTMENT OF AGRICULTURE. 


the decays were so badly eaten out by insects as to preclude any 
description of the rot. By reason of this, some light infections of — 


Polyporus amarus may have been included under secondary rots, | 


but such cases have undoubtedly been very rare. : 

Of the 59 infections of secondary rots examined, only 9 resulted — 
in culls of any importance, the highest percentage of unmerchant- 
able timber in relation to the total volume of the tree being 19.5 
percent. In all the remaining 50 trees the infections were negligible. 
These figures show secondary rots to be of only trivial importance in 
reducing the merchantable volume; hence, such decays are not 
further considered in this paper. | 


THE DRY-ROT. 


The dry-rot of incense cedar, termed by eastern workers ‘ pecki- 
ness’’ or ‘‘pin-rot,”’ caused by the fungus Polyporus amarus Hedgc., 
was first described and figured by Harkness (7) but no cause was 
given. Next Von Schrenk (26, 67-77, pl. 2, 4, 5) described and 
figured the disease without stating the cause, and later (28) he 
mentions Polyporus libocedris, but without giving a description of 
type specimens. Hedgcock (10) first definitely assigned the cause 
of the dry-rot to Polyporus amarus sp. noy. and described the fungus. 
Later Meinecke (15, p. 35-37) presented a brief description of the 
sporophore, accompanied by a photograph of a typical fully devel- 
oped bell-shaped specimen, with the upper surface partially destroyed 
by insects. Murrill (24, p. 25) places the fungus in the genus Fomes, 

Harkness and Moore, Mayr, and Sargent have attributed the cause 
of the dry-rot to Daedalea voraz Hke., but Von Schrenk (26, p. 67-68) 
has shown this to be an error. Farlow and Seymour (5, p. 169) and 
Bryant (1, p. 15) have made the same mistake. 

The dry-rot is very widely distributed. It has been found at 
elevations varying from 650 to 6,480 feet as far north as Oakridge, 
Lane County, Oreg., west to the west of China Flat, Humboldt 
County, Calif., east to Shaver, Fresno County, Calif., and south to 
the north and east of Mentone, San Bernardino County, Calif. In 
fact, from all indications and hearsay evidence it is quite reasonable 
to presume that dry-rot is more or less prevalent in incense cedar 
throughout the range of the host (30, p. 150-152). 


THE SPOROPHORE. 

Since Hedgcock’s description was published, so many sporophores 
have been collected that the original description may be supplemented 
_ by the following, which is based on the examination of 25 sporophores, 
both fresh and old: | 


Polyporus amarus.—Pileus soft and mushy when young, then rather tough and 
cheesy, finally becoming hard and chalky when old, ungulate, bell shaped or occa- 


Bul. 871, U. S. Dept. of Agriculture. PLATE I. 


— 


; 
; 
} 


A FRESH SPOROPHORE OF POLYPORUS AMARUS ON A DOWN TREE. 
Photographed by Gravatt. 


PLATE II. 


Bul. 871, U. S. Dept. of Agriculture. 


AN OLD SHOT-HOoLE CuP. THE ORIGINAL SPOROPHORE ISSUED FROM THE 


KNOT HOLE AT THE TOP. 


Photographed by Meinecke. 


DRY-ROT OF INCENSE CEDAR. 9 


sionally subapplanate, often spuriously stipitate from knot holes, 4 to 15 by 5 to 22 
by 5 to 20 cm., commonly 7 to 10 by 11 to 13 by 8 to 13 cm., occasionally abortive 
without hymenial layer, then assuming irregular shapes; surface pubescent when young, 
rimose and chalky when old, at first buff, then tan, and often blotched with brown 
when attacked by insects; margin obtuse, frequently having an outer band of darker 
brown, often slightly furrowed; context homogeneous,! lemon-yellow, later buff to 
- tan, usually darker near the surface when old, slightly bitter to the taste, 4 to 14 cm. 
thick, commonly 9 to 11 cm., usually friable when dry but occasionally becoming 
partially horny, hard; tubes not stratified, lemon-yellow within, cylindric 0.2 to 3 
em. in length, shorter next the margin, mouths circular or slightly irregular, 1 to 3 
to a millimeter, lemon or sulphur yellow during growth, turning brown when bruised 
or old, becoming lacerate; under surface of the hymenial layer sometimes exuding 
clear yellow drops of liquid, sweetish to taste; spores hyaline or slightly tinged with 
yellowish brown, smooth, ovoid (200) range 3 to 6.5 » by 4.5 to 9 uw; standard size 
3.5 to 4.5 pw by 6.5 to 7 yp, oP ccntad: cystidia none. 


The following table presents detailed measurements of 24 sporo- 
phores of Polyporus amarus: : 


TaBLE I.—Sporophore measurements of the incense-cedar dry-rot fungus. 


cm. cm. cm. cm. cm. cm. cm. Cm. -- Cm, 
3.8by 4.8by 8.3 8.0 by 13.0 by 13.0 9.5 by 17.0 by 13.3 
4.2by 5.5 by 5.5 9.0by 11.5 by 9.9 9.8 by 13. 2 by 13.0 
6.0 by 7.3 by 8.6 9.0 by 10.0 by 10.0 10.3 by 14.9 by 14.8 
6.8 by 11.2 by 12.3 9.0 by 10.5 by 11.0 11.4 by 20.7 by 19.8 
7.5 by 11.4 by 9.0 9.0 by 13.3 by 12.0 12.0 by 16.4 by 10.8 
7.5 by 17.0 by 8.1 9.1 by 10.7 by 8.5 DL by 2. 2 byA2: 5 
7.6by 11.4 by 9.5 9.1 by12.4by 8.9 14.5 by 22.0 by 13.0 
8.0 by 12.5 by 10.0 9.5 by 14.7 by 11.0 14.8 by 12.7 by 16.5 


The sporophores, which last for one season only even at best, are 

not at all common, a statement which is supported by the number 
of years the dry-rot was known before the cause was definitely 
determined. During certain years sporophores seem to be very 
rare. They most commonly occur in the summer, and especially 
in the fall, but occasionally are found at other seasons. Observa- 
tions record two fresh ones in March in a rather mild climate at an 
altitude of about 3,000 feet in the Sierra Nevada. Another was 
- found in a different locality in June. No sporophores have been 
found developing later than October, but occasional fresh ones 
may be carried over from a previous fall into the winter in a frozen 
condition. They are then destroyed in the spring. 

Typically the sporophores are produced on living trees but are, 
on occasions, found on dead fallen trees. (PI. I.) Seven such cases 
have been observed during the past five years. In five of these it 
was possible to determine the time which elapsed between the felling 
of the tree and the appearance of the sporophore. Three of the 
,sporophores were produced 3 years, one 4 years, and one 27 years 
after the trees had been cut. As to how long the mycelium may 


1 The substance of the sporophore not including the outer layers. 


182803°—20—Bull. 8712 


10 BULLETIN 871, U. S. DEPARTMENT OF AGRICULTURE. 7 


persist in a dead fallen tree it is impossible to state, but the last 
figure given indicates a rather extended period in some cases. These ~ 
cases refute the statements of Harkness (7) and Von Schrenk (26, — 
p. 75) that the mycelium does not grow after the death of the tree. ; 
On dead down trees the sporophores were never half bell shaped or _ 
ungulate, but were more typically near the subapplanate type. a 
Since so few cases of sporophores on dead fallen trees have been — 
recorded during a rather extended period, it is safe to assume that 
infected fallen trunks are of slight importance from the standpoint 
of forest sanitation in infecting living trees through the production _ 
of sporophores. | 
Although sporophores are rather rare, an accurate indication of — 
the place formerly occupied by a sporophore is supplied by the ~ 
shot-hole cup (Pl. II), so termed and described by Meinecke (15, © 
p. 23, 46). These shot-hole cups appear as cup-shaped depressions 
.below a knot, the depression being riddled with numerous fine holes. 
At first they have the color of the freshly opened bark of the tree, 
but later become weathered and gray with age. They are formed 
in the followmg manner: The soft fleshly or cheesy sporophores 
issuing through knots are usually soon eaten by squirrels and micro- 
lepidopterous larve. Some of these larve then bore into the bark 
of the tree, where they are sought after by woodpeckers, which 
chop out a cup-shaped depression in the bark, corresponding to the 
place formerly occupied by the sporophores. This depression is 
riddled with what appear to be numerous fine shot holes, the burrows 
of the insect larve. . 
The presence of a shot-hole cup is just as reliable an index of dry- ~ 
rot in a tree as is a sporophore. However, the same diagnostic 
values in relation to the age of the fungus plant in the tree, and 
consequently the extent of the resulting decay, must not be attached 
alike to sporophores and fresh and old shot-hole cups. An old, 
gray, weathered shot-hole cup would indicate the most extensive 
serious decay, while a fresh shot-hole cup, in turn, would indicate 
more extensive decay than a sporophore, since it is evident that 
more time must elapse before a shot-hole cup is formed than a sporo- 
phore and the longer the fungus plant lives in the heartwood the 
greater the amount of decay resulting. 
The number of sporophores occurring on a standing living tree is 
typically one. Von Schrenk (27, p. 205) gives the number as : 
: 


usually one, but it must be remembered that at this time no descrip- 
tion of Polyporus amarus had appeared, so it can not be stated 
definitely that Vou Schrenk was referring to this fungus. However, 
Meinecke (15, p. 46, pl. 12) gives the number as typically one. Some- 
times two have been found. As many as five shot-hole cups have 
been observed on a single living tree, but an examination of their con- 


-DRY-ROT OF INCENSE CEDAR. 14 


dition invariably showed that they had been developed successively, 
or at least not more than two in the same year. But on dead down 
trees the above rule does not hold. Of the seven known occurrences 
‘(see p. 9) several trees had two or more fresh sporophores. 

During the course of the actual work of dissecting the trees exact 
data were secured on three sporophores and 17 shot-hole cups dis- 
tributed on 15 trees, as follows: Two abortive sporophores on separate 
trees, one normal sporophore and two shot-hole cups on the same 
tree, 10 shot-hole cups on separate trees, 2 shot-hole cups on the 
same tree, and 3 shot-hole cups on the same tree. 

That there might be a definite orientation of the sporophores in 
standing living trees was suggested by the work with Trametes pini of 
Moller (18), in which he found 89.4 per cent of the sporophores on the 
westerly side of the trees, attributing this to the facts that the pre- 
vailing winds were from the west, the trees were most strongly struck 
by rain on the west side, and therefore the branch stubs (a very com- 
mon point of infection) were more moist on that side. Furthermore, 
he states that the sporophores appear at the same spot at which the 
infection commences. Weir and Hubert (32, p. 30), working with 
the Indian-paint fungus (Echinodontiwm tinctorium) on western hem- 
lock (T'suga heterophylla), found that most of the sporophores had a 
northwest to north-northeast orientation. However, the sporo- 
phores and shot-hole cups of Polyporus amarus are rather equally 
distributed to all points of the compass, showing no definite relation 
to any particular direction, and in not a single case was the sporophore 
developed at the same point at which the infection apparently com- 
menced. 

These sporophores and shot-hole cups occurred on trees ranging 
from 24.2 to 44.2 inches diameter breast high. The youngest tree 
which bore a shot-hole cup was 193 years old at stump height (1.5 
feet), the next youngest was 221 years of age (28 years older), and 
the oldest, 379 years. Between the ages of 193 and 379 years the 
trees with sporophores or shot-hole cups were rather equally dis- 
tributed. These figures are not given for the purpose of establishing 
a diameter breast high or age range for trees in which Polyporus 
amarus fruits; the number of trees examined forms entirely too 
meager a basis. 

Sporophore formation did not seem to be in any way related to the 
width of the sapwood, since the sapwood in the trees which had 
formed sporophores varied from comparatively narrow in somé cases 
to rather wide in others. 

The heights at which the sporophores and shot-hole cups were 
found varied from 9.6 feet to 48.7 feet from the ground level, but 
thirteen of them occurred between 15 and 30 feet and only two at a 
greater height than the latter figure. Sporophores or shot-hole cups 


12 BULLETIN 871, U. S. DEPARTMENT OF AGRICULTURE. 


always indicate that there is well-developed dry-rot in the heartwood. 


In such infections it is generally possible to distinguish three stages in 
the affected heartwood, with upper and lower limits. These stages — 
for convenience are termed total extent, unmerchantable extent, and’ 


maximum concentration. ‘Total extent’’ is expressed by giving 


the height in feet in relation to the ground level of the lowest and — 


highest point in the bole of the tree invaded by the fungus without 
regard to radial extent. By “unmerchantable extent” is meant the 
portion of the bole rendered valueless for lumber by the dry-rot, 
while ‘‘maximum concentration”’ covers that portion of the bole in 
which the decay seems to be at its worst. The upper and lower limits 
of all three of these stages may at times coincide, but especially 
that of the unmerchantable extent and maximum concentration. It 
is self-evident that these last two mentioned can never exceed the 
total extent. 

The sporophores and shot-hole cups invariably appeared between 
the upper and lower limits of the maximum concentration. The 
lower limits varied from 3 to 25 feet below the sporophores or shot- 
hole cups, and the upper limits from 4 to 45 feet above them. In every 
case except one the lower limit of the unmerchantable extent was at 0. 
In other words the bole of every tree was unmerchantable, at least 
from the ground level to the sporophore or shot-hole cup. In the one 
exception the unmerchantable extent did not commence until 8.2 
feet from the ground level. This was due to the presence of a large 
open fire scar extending from 0 to 10.8 feet. The fungus distinctly 
avoids the dried-out wood around open wounds, which habit will be 
fully discussed laterin thispaper. The upper limits of the unmerchant- 
able extent were variable. In the two abortive sporophores the un- 
merchantable portion extended for 10 and 24 feet, respectively, 
above the sporophores, while the extent above the shot-hole cups was 
23 and 53 feet. 

The total extent in every tree with sporophores except one (see 
above, under unmerchantable extent) reached from the sporophore or 
shot-hole cup to the ground level, but the upper extent was variable, 
being for the two sporophores 24 and 25 feet, respectively, and for the 
shot-hole cups ranging from 24 to 53 feet. 

From the figures available it is impossible to make an exact state- 
ment as to the range of the total extent, unmerchantable extent, and 
maximum concentration of the dry-rot in trees with sporophores or 
shot-hole cups, except that it may be safely assumed not only from 
the figures at hand but from observations on logging areas that the 
bole of a tree will always be unmerchantable from the ground level 
to a variable height above a sporophore or shot-hole cup. But it 
must be remembered that an old shot-hole cup indicates a greater 
development for the fungus plant in the tree than does the first 


i.e ee 


a 


©. OC RR il ee ee Ee EE I ALAS 


- -DRY-ROT OF INCENSE CEDAR. 13 


appearance of a sporophore or fresh shot-hole cup, and one should 
be influenced accordingly in judging the condition of a standing tree. 


THE DECAY. 


The dry-rot, described and pictured by Harkness (7), Von Schrenk 
(26, p. 68, pl. 2), and Meinecke (15, p. 46, pl. 12), is a very characteris- 
tic decay, most closely resembling the so-called peckiness of the 
- eastern cypress (Taxodium distichum). Von Schrenk (26, p. 52-53) 
points to this analogy, even suggesting that the two diseases may he 
caused by the same fungus, but Long (12) has disproved this theory. 
The former investigator (29, p. 30) also calls attention to the macro- 
scopical similarity between this dry-rot and the brown-rot of redwood. 

Typically, the decay consists of vertically elongated pockets, 
varying in length from one-half inch to about a foot, which are filled 
- with a brown friable mass, and the line of demarcation between the 
sound and decayed wood is very sharp. In some of these pockets 
small cobweblike or feltlike masses of white mycelium occur. The 
pockets are separated from each other by what appears to be sound 
_ wood, although in some cases streaks of straw-colored or brownish 
wood may extend vertically between two pockets. This is especially 
noticeable between young pockets. When immature the decay is 
faintly yellowish brown, soft and somewhat moist, and not broken 
up in the pockets. At times the mature pockets may be several feet 
long and rather broad; this type always occurs in connection with 
healed-over wounds, particularly healed fire scars in the butt of the 
tree. The decay has never been found in living sapwood and is 
usually confined to the heartwood of the trunk, but in very badly 
decayed trees the dry-rot sometimes extends into the heartwood of 
the larger limbs. . 

In the aggregate, the immature decay or advance rot extends but 
a short distance vertically in advance of the typical decay, and a dis- 
tance of 2 feet beyond the last visible evidence of decay to the average 
eye will usually exclude all immature decay. This immature decay 
is very difficult to detect, occurring as it does in pockets, with the 
color in the very earliest stages differing but slightly, if at all, from 
the normal wood. 

An occasional pocket may occur several feet in advance of the main 
‘body of decay, and while the wood of the pocket itself is of course 
greatly weakened, the intervening wood is probably very little 
affected, since the fungus hyphe are very sparingly found between 
- pockets of decay. In all, 566 trees containing typical dry-rot were 
dissected. 

Typical dry-rot with small masses of white mycelium in some of 

the pockets is shown in Plate III. 


14 BULLETIN 871, U. S. DEPARTMENT OF AGRICULTURE. 
STRUCTURE OF THE DISEASED WOOD. 


The structure of the decayed wood in mature pockets was found 
to be practically as described by Von Schrenk (26, p. 70-71). Inthe | 
very early stages of decay (Gmmature pockets), cracks in the cell walls 
such as he describes for old pockets, which were most common in the 
pits, were rather rare. It was also found that cracks often started 
from the holes in the cell walls made by the hyphe of the fungus. — 
The color of the decayed wood varies from light to dark brown, de- 
pending on the state of decay. | 

In some of the decayed wood examined the bordered pits gaye | 
much the same appearance as is often presented by starch grains in _ 
a plant cell which have been partially corroded by diastase. Further 
examinations showed this condition of the bordered pits to exist in 
badly decayed wood, in slightly decayed wood, in the straw-colored 
wood between the pockets, and in sound wood. Immediately upon 
treatment with xylol, and more slowly with oil of turpentine, the pits 
resumed their normal smooth appearance; consequently, the con- 
dition is the result of a deposit on the membrane of the pits, but as to 


the nature of the substance deposited or the cause of its deposition q 


the writer is unable to give any information. At least, the fact that 
the deposit was found on the pits in sound wood proves that it is in 
no way a result of the action of the fungus. 

Badly decayed wood, slightly decayed wood, straw-colored and 
brownish colored wood Heteces the pockets, and sound wood were 
treated with various reagents, the results in each case being practi- 
cally identical. Anilin sulphate colored the cell walls a brilliant 
yellow. A cherry to violet-red stain was produced by treatment 
with phloroglucin and hydrochloric acid. Chloriodid of zine and 
alcoholic iodin with sulphuric acid both stained the walls a yellowish 
brown color. After treatment for 12 hours with Javelle water, the 
wood turned a yellowish brown upon the application of chloriodid of 
zinc, and a brilliant yellow with the addition of anilin sulphate. 
The above tests demonstrate that the lignin compounds in the cell 
walls are not changed, in so far as our present knowledge of the nature 
of so-called lignin enables us to judge. Therefore, it seems probable 
that the fungus extracts from the cell walls either the cellulose or 
some other compound yet unknown. 


THE MYCELIUM. 


Hyphe were very rare in the pockets of badly decayed wood or in 
the apparently sound wood immediately surrounding these. Proof of 
their having been quite commonly present, however, was afforded 
by the tiny holes in the cell walls of the decayed wood through which 
the hyphe had passed. In the slightly decayed wood and the wood 


DRY-ROT OF INCENSE CEDAR. 15 


immediately surrounding it hyphz were found abundantly. They 
bore through the cell walls in all directions, showing no preference 
for the bordered pits and apparently making no distinction between 
spring and summer wood. ‘They were rarely found in the medullary 
rays. 

Harkness (7) states that ‘‘the mycelium does not leave behind the 
slightest microscopical trace of its presence in the sound wood when . 
passing from pocket to pocket.” In some of the brownish and straw- 
colored streaks of wood which extended vertically from pocket to 
pocket of immature decay, hyphze were found sparingly. These 
usually followed the lumen of a tracheid, but sometimes passed through 
the wall into the lumen of the adjacent tracheid. The writer was 
unable to follow the entire course of the hyphe in any case from 
pocket to pocket and therefore could not verify Von Schrenk’s 
statement (26, p. 73) that ‘‘between the rotted areas the hyphe 
usually extend directly from hole to hole.’”’ In some cases no hyphe 
were encountered in the discolored streaks between the young pockets, 
but this was probably due to the failure to make sections at the proper 
place. Hyphse were commonly present in the apparently sound 
wood surrounding young pockets to a distance of 4 mm. (0.157 inch), 
and sparingly from that point to 8 mm. (0.314 inch) in a horizontal 
direction. Owing to lack of proper material it was possible to make 
only a limited study of the vertical distribution of the hyphz. In 
the case of the last (highest) pocket in a diseased tree the hyphee 
were abundant to a distance of 1.5 cm. (0.6 inch) above the pocket, 
and sparingly from that point on to 7.8 cm. (3.07 inch), where they 
ended. 

Observation leads to the inference that the hyphe are able to 
pass for some distance through the sound wood without causing the 
slightest microscopical change in the color or structure other than 
an occasional hole in a cell wall as the hypha passes from the lumen 
of one tracheid to that of another. In certain cases isolated pockets 
of decay have been found at a maximum distance of approximately 
4.3 meters (14.3 feet) from the nearest pocket of decay, yet a very 
careful analysis showed that there was only one possible means of 
entrance for the fungus into the tree, and consequently the hyphe 
must have traversed this distance through the sound wood before 
causing another pockét of decay. 

As to why the fungus decays only the wood in localized pockets 
which are separated by areas of practically sound wood it is im- 
possible to state, since nothing is known of the influence of a possible 
variation of the chemical and physical properties of the wood on the 
fungus. Orit may be that the answer to the question lies in another 
direction; that is, the hyphe in their work of destruction after a 


16 BULLETIN 871, U. S. DEPARTMENT OF AGRICULTURE. 


certain time produce conditions unfavorable for their further develop-— . 
ment and are forced to seek another field. 
In the wood the hyphe are hyaline, varying in diameter from 


0.8 to 3.34 but being most commonly 0.8 to 1.7 u, branching and 


rebranching into the finest threads, anastomosing, sparsely septate, 
rarely constricted at the septa, and sometimes having clamp connec- 
- tions. They never become so abundant as to fill the tracheids 
completely. Usually the hyphe pass from the lumen of one tracheid 
into that of an adjoining tracheid and then extend up or down 
the lumen, but occasionally a single hypha may cross several 


tracheids in a radial or tangential direction without extending upor — 


down their lumens or giving off any branches. The holes in the 
walls of the tracheids made by the hyphe are very small, particularly 
so since the hyphe are often sharply constricted when passing through 
the walls. Rarely the hyphe are irregular in shape. 

The hyphze composing the cobweblike and feltlike masses of 
mycelium in the badly decayed wood (see p. 13) are usually 
hyaline, but sometimes have granular contents. They vary in diam- 
eter from 0.8 to 40 w, are richly branched, more commonly septate 
than the hyphe found in the wood cells, and sometimes constricted 
at the septa. No clamp connections were found. They frequently 
anastomose. They were often very irregular in shape, and globose 
or spindle-shaped swellings were frequent. 


OTHER FORMS OF DECAY. 


Besides the typical decay already described, two other very 
characteristic forms were found. One of these is characterized by 
small spots or pockets of brown decayed wood varying in width from 
0.5 to 2 mm. (0.02 to 0.08 inch) and in length from 1 to 4 mm. 
(0.04 to 0.16 inch), with the long axis running vertically in the wood. 
In some cases larger decayed spots are formed by the joining of two 
or more smaller ones. The tiny decayed spots are separated by 
apparently sound wood. As for the structure of the decayed wood 
and its reactions with various reagents, these agree exactly with the 
typical form of dry-rot (see p. 14), and this decay is very probably 
an abnormal form of the typical decay caused by Polyporus amarus. 

The other form of decay consists of very small white spots (measure- 
ments as given above) in which the wood has been reduced to cellulose, 
separated by apparently sound wood. ‘The structure of the decayed 
wood is practically as described by Hartig (8, p. 53-54; 9, p. 36-37) 
for decay caused by the ring-scale fungus (Trametes prs cid the rot 
under consideration is undoubtedly caused by this fungus, since, 
through the courtesy of Dr. James R. Weir, the writer has been 
privileged to examine sporophores of Trametes pint with the typical 


Ee ent 


a 


PLATE III. 


TYPICAL DRY-ROT IN INCENSE CEDAR CAUSED BY POLYPORUS AMARUS. 
Photographed by Meinecke. 


Bul. 871, U.S. Dept. of Agriculture. 


DRY-ROT OF INCENSE CEDAR. 17 


decay collected on incense cedar in Oregon. As far as the writer can 
ascertain, this is the only collection of its kind now known. Neither 
of these two decays affects the living sapwood. 

The mycelium of both is the same and differs from the mycelium 
of typical dry-rot. Studies were made where these two decays were 
distinct, where they graded into one another, and where they graded 
into the typical dry-rot. The hyphe vary from hyaline to dark 
brown in color, with a diameter ranging from 0.8 to 6.7 » but most 
- commonly 3 ». The heavier brown hyphe often branch profusely, 
_ the branches becoming smailer and lighter in color. The smallest 
ones are usually hyaline, and so are some of the larger hyphe. In ~ 
some instances the smaller hyphz are merely continuations of the 
heavier strands. The hyphe are sparsely septate, often constricted 
at the septa and without clamp connections. They bore through the 
cell walls in all directions, but seemingly more often through the 
tangential walls. No preference is shown for the bordered pits. ‘They 
are characteristically sharply constricted when passing through the 
walls of the tracheids and have marked attachment organs. The 
hyphe did not enlarge in the secondary lamelle when boring through 
the wall, as is shown by Hartig (8, 9) for Trametes pini. Quite typi- 
cally, a single strand may pass tangentially through as many as 20 
or 30 tracheids, often completely traversing an annual ring, without 
sending any side branches into the lumens. This mycelium appears 
to agree closely with that described and figured by Von Schrenk 
(26, pp. 73-74, pls. 4-5), but which he assumed to be secondary and 
in no way connected with the dry-rot. Often the hyphe seem to 
pierce a cell wall without developing in the lumen of the tracheid 
entered, a condition recorded by Hartig (8, p. 46) for Trametes pini. 
However, in so many cases unattached fragments of hyphe were 
found in tracheids through the walls of which the hyphz had pene- 
trated without developing in the lumen that most probably the hyphe 
did develop but were broken off in sectioning. 

In all, 80 trees which contained one or both of these decays were 
dissected. The Trametes pini decay eccurred alone in 61 of these, 
the dry-rot in small pockets in 11, and both forms in 8 trees. In 28 
of the 61 trees having the Trametes pini decay, this was either inter- 
mingled, graded into, or very close to pockets of typical decay without 
_ there being any line of demarcation between the two. In certain 

cases the two decays could be absolutely traced to the same source of 
infection. Tree No. 40 on the intermediate area forms an excellent 
example. This tree had two small open fire scars in the butt just at 
ground level. There was a light infection of typical pockets of dry-rot 
extending from ground level to a height of 7.3 feet. At this point 
Trametes pini decay appeared without any line of demarcation and 
182803°—20—Bull. 871——3 


18 BULLETIN 871, U. S. DEPARTMENT OF AGRICULTURE. 4 


extended to 29.4 feet, and then the typical pockets of dry-rot reap- — 
peared, which ultimately ended at a height of 41.4 feet. The only — 
possible means of entrance for the two forms of decay were the small — 
open fire scars at the ground level. A similar condition is presented — 
in tree No. 7 on the intermediate area. This tree had a large open 


fire scar extending from the ground level to a height of 8feet. Typical | 


dry-rot entering through this open wound began at 6 feet, extending 
to 9.7 feet, where it merged into Trametes pint decay, which then gave 
place to the typical dry-rot at 14.7 feet, and the latter finally ended 
at a height of 20.7 feet. No line of demarcation could be distinguished 
_ between the two decays, and the point of entrance of the infection was 
at the open fire scar. Other examples could be cited, but these seem 
sufficient. 

In the eleven trees in which the dry-rot in small pockets occurred 
it was either very close to or intermingled with typical dry-rot in six, 
and in four of these six trees both forms of decay could be exactly 
traced to a common point of entrance. There were no apparent lines 
of demarcation in any instance between the two forms of decay.* In 
tree No. 392 in the intermediate range typical pockets of dry-rot 
extended from ground level to 28.7 feet. At this point the typical 
decay changed to the small pockets, and this form occupied the 
heartwood to 36.9 feet, where the decay stopped altogether. 

Finally let us consider the eight trees in which both the dry-rot in — 
small pockets and the Trametes pini decay were found. In two of 
the trees the two decays occurred in different parts of the bole. In 
two trees the decays were very close together, while in four trees the 
two were accompanied by pockets of typical dry-rot. Tree No. 296 
on the intermediate area offers an excellent illustration of this last 
condition. In this tree the dry-rot in small pockets, the Trametes pim 
decay, and typical pockets of dry-rot were intermingled, and transi- 
tion stages between the three forms were apparent from ground level — 
to a height of 30.3 feet. In four of the eight infected trees 1t was 
possible to trace the entrance of both decays to the same point, 
healed fire scars. There were-no lines of demarcation separating the 
various decays. ; 

The interesting point in connection with the two forms of dry-rot 


and the decay caused by Trametes pint is that they occurred in the — 


same substrata, either merging into one another or actually inter- 
mingling without any well-defined lines between them. That such 
lines of demarcation between different decays are the general rule © 
has long been accepted and has been most recently expressed again 
by Weir (81). Hence, it is particularly interesting to find two — 
exactly opposite types of decay intermingling so freely. It is quite — 
probable, however, that such occurrences in the future will come to 
be recognized as quite common, The writer has already found 


DRY-ROT OF INCENSE CEDAR. 19 


decays caused by Trametes pint and by Fomes laricis (the chalky 
quinine fungus) intermingled in the wood of living Douglas firs on 
several occasions, while down logs in the woods are often mycological 
gardens of wood-destroying fungi with the decays completely 
intermingled. 

Both the dry-rot in small pockets and the Trametes pini decay are 
nearly always found around decayed knots or following along healed 
wounds, mainly those caused by fire. Where the infections occur 
around knots the decay is almost invariably confined to the imme- 
diate neighborhood of the knot, resultig in little or no loss in the 
merchantable contents of the tree. Where any appreciable quantity 
of wood was rendered unmerchantable, the decays were almost 
invariably in intimate connection with healed-over wounds caused 
by fire, frost, or lightning, particularly the first, throughout their 
extent. Exceptions to this rule did occur. In one tree, for example, 
the Trametes pint decay extended for a distance of 23.5 feet in the 
center of the tree above an open fire scar without being in connection 
with any other wound. But the fire scar was very large, extending 
deeply into the tree and undoubtedly had a far-reaching influence 
on conditions in the heartwood. In another tree (tree No. 40 on the 
intermediate area; see p. 17) this same decay extended for 22.1 
feet in between two areas of typical dry-rot without following along 
any wound. The dry-rot in small pockets was found in one instance 
_to extend for a distance of 8.2 feet, not in connection with a wound 
but merely as an extension of typical dry-rot. This case has already © 
been cited (tree No. 392 on the intermediate area; see p. 18). 

The above fact suggests that the dry-rot in small pockets may be 
the result of the influence on the dry-rot fungus of changed condi- 
tions in the heartwood, either physical, chemical, or both, induced 
by the presence of wounds or knots. 3 

In further support of this hypothesis, it is almost invariably the 
rule wherever typical dry-rot is found along healed fire scars in the 
butt of a tree that instead of the pockets of normal size, one or more 
long continuous pockets of the dry-rot follow immediately along the 
scar throughout its length and invariably run out close to the end of 
the scar. A maximum length of 10 feet has been attained. Such 
pockets have never been found except in connection with wounds. 
This seems to prove that variations in the typical form of dry-rot 
may be induced by certain types of wounds in the tree. | 

The fact that the Trametes pint decay is usually found in the 
immediate vicinity of knots or healed-over wounds may be taken to 
indicate that incense cedar is an unsuitable host for Trametes pini 
and that the organism can rarely progress much beyond the point of 
‘infection. This would also explain the rare production of sporo- 
phores and the fact that in the only known collection, to cite Weir's 


20 BULLETIN 871, U. S. DEPARTMENT OF AGRICULTURE. 


words in a letter to the writer, ‘‘The sporophores are of the small — 
depauperate type which I find occasionally on trees at high eleva- — 
tions or on old punk knots from which the original sporophores have 
fallen and are reviving.” 

However, for the purposes of this paper these decays may all be 
treated as one and the same, since the dry-rot in small pockets and 
the Trametes pini decay are of negligible importance both in the 
number of infections and amount of cull resulting. Hence, except 
in the data on the rate of spread of the dry-rot, they are included in 
all subsequent pages with the typical decay of Polyporus amarus. 

No relation was found between the width of the sapwood and the 
extent of decay; trees with wide and narrow sapwood seem to be 
equally affected with the dry-rot. 


RAPIDITY OF SPREAD OF THE DRY-ROT., 


Although the rapidity of the spread of decay caused by heartwood- 
inhabiting fungi in standing trees has always been of interest, very 
little work has been done on this line. Hartig (9, p. 115-116), 
mentions this briefly in relation to the rot caused by Polyporus 
(Fomes) vgniarius in oak. More recently Miinch (23) has published 
some interesting results from studies of the same fungus and host, 
showing a wide variation of 3.8 to 37.5 cm. (0.12 to 1.23 feet) in 
the yearly vertical progress of the decay, with an average of 5 to 9 cm. 
(0.16 to 0.30 of a foot). No tangible difference was found between 


the upward and downward rate of spread from the point of infection. — | 


Miinch’s results are based on an analysis of only 15 cases, and 
their value is further reduced by the fact that in determining the 
age of the infection which entered a tree through an open wound, he 
assumed that infection must have occurred the year the wound was 
made, or at least a very few years subsequently, even though the 
wound was still open at the time of analysis. True enough, as 
shown by Minch (23), Fomes zgniarius attacks not only the heart- 
wood but the sapwood of many trees and kills the cambium, causing 
cankers with subsequent callusing, and by counting the number of 
annual rings in the callus at the point of infection the age of the 
decay can be determined, provided a canker was formed the year of 


infection; but this is not uniformly the case, to judge from Miinch’s ~ 


(23, p. 519) own statement that ‘‘ Homes igniartus produces exceed- 
ingly variable cankers. Sometimes small points of infection which 
are scarcely noticeable and are soon healed perfectly . . .” 

In securing the figures on the yearly rate of spread of the dry-rot, 
only those infections were considered the entrance of which could 


be absolutely traced, without any other possibilities, to a healed 


scar for which it was possible to determine the exact dates of q 


occurrence and closure, For example, an infection is found ina 


DRY-ROT OF INCENSE CEDAR. 91 


tree which was cut in 1915. The fungus entered through a healed 
fire scar which occurred in 1781 and was completely closed by callus- 
ing in 1816. By subtracting 1781 and then 1816 from 1915 it is 
seen that the fungus has been in the heartwood a minimum of 99 
and a maximum of 134 years. During this period resulting decay 
has progressed a vertical distance of 34.2 feet in the bole, or a yearly 
average of 0.25 to 0.34 of a foot. The radial extent of the decay is 
disregarded, since this is of little importance from a practical view- 
point. Any serious infection usually extends more or less through- 
out the heartwood in a radial direction. Of course, the above 
method does not give a single figure for the yearly average progress 
of the dry-rot, but it does give the exact minimum and maximum 
limits between which the true figure lies. 

In all 99 infections were possible of analysis by this method. 
The great majority of these commenced at ground level, entering 
through fire scars and extending up the bole. Ten of the infections 
were traced to wounds high enough up on the trunk, however, to 
make possible a comparison of the upward and downward progress 
of the dry-rot. This meager basis indicated that the dry-rot, in the 
main, progresses more rapidly downward than upward, although 
in individual cases this relation may be reversed. 

The yearly progress of the decay is exceedingly variable. At one 
extreme there is a tree in which the fungus had been vegetating be- 
tween 124 and 135 years, but the resulting dry-rot had only attained 
a length of 0.4 of a foot, or a minimum average yearly progress of 
0.002 and a maximum of 0.003 of a foot. The tree was 147 years 
old. At the other extreme, the fungus in from 10 to 58 years caused 
decay extending over 30.9 feet of the bole of another tree, that is,a 
minimum average progress of 0.53 of a foot a year and a maximum 
of 3.09 feet. This tree was 240 years old. Again, in a 107-year-old 
tree the fungus caused a decay with a minimum average progress 
of 0.87 of a foot and a maximum of 1.90 feet a year, extending a 
total of 40 feet vertically. In the main, however, the minimum prog- 
ress of the dry-rot varied from 0.01 to 0.20 of a foot a year, while the 
maximum ranged from 0.01 to 0.35 of a foot. Higher yearly rates 
than the upper limits stated were not uncommon, but lower rates 
than 0.01 of a foot were rare. 

These figures clearly demonstrate the slow progress of the dry-rot 
fungus in causing decay. Generally it required from 50 to 300 years 
to bring about any far-reaching dry-rot. In the heartwood of cer- 
tain individuals the fungus had vegetated for decades, the resulting 
decay only extending 1 or 2 feet from the point of infection. A 
similar condition was found by Minch (loc. cit.) for Polyporus (Fomes) 
wmarius attacking oak. As to why the development of the dry-rot 
fungus in certain cases is so inhibited the writer is unable to present 


a2 BULLETIN 871, U. S. DEPARTMENT OF AGRICULTURE. 


es 
q 


any definite information, but certainly the chemical and physical 
condition of the substratum must have a strong bearing on this 
phenomenon. Hartig (9, pp. 115-116) believes in the case of Poly- 
porus (Fomes) igniarius that the width of the annual rings of the 
wood is not without influence on the rapidity of decay. Minch (20, 
p. 156) states that the more rapidly grown coniferous wood, conse- 
quently that with the broader annual rings, is more speedily decayed — 

by Fomes annosus than slower grown wood with narrower rings, even — 
extending this to broad and narrow rings in the same individual. 
Later (22, p. 403-406), he shows that suppressed individuals of beech 
artificially infected with Stereum purpureum. S. rugosum, Polyporus — 
(Fomes) igniarius, and P. (F.) fomentarius were more seriously de- — 
cayed than dominant thrifty trees, yet it is just such suppressed trees © 
which must have the narrowest annual rings. Finally (23, p. 521), 
the same investigator finds no relation whatsoever between the 
breadth of the annual rings and the rapidity of decay in the wood of — 
oak attacked by Polyporus (Homes) igniarws. 


PURPLE COLORATION. 


Accompanying the dry-rot is a purplish coloration of the heartwood 
which is very characteristic. The writer does not find this mentioned 
in any description of the dry-rot so far available, but it is well known — 
to the lumberman. This color varies from a light salmon-red or pink ~ 
to a pronounced purplish red in trees with heavy decay, where it may — 
stand out strongly in cross section as a ring surrounding the decayed — 
area or present a mottled appearance over the entire heartwood. 
Where the coloration is faint it is sometimes impossible to detect it 
in cross section, but if the tree is split longitudinally the color is 
readily apparent, although it often fades out entirely after several — 
days’ exposure to light and air. It usually commences at ground © 
level and extends upward, but may start at varying heights. | 

Microscopical studies of this colored wood did not show any devia- 
tion from sound wood. No hyphe were found except at points im- — 
mediately adjacent to pockets of dry-rot. No chemical or physical — 
examination was possible. . 

In all, 634 trees were dissected in which the purple coloration was — 
present. The notes from Cow Creek did not include data on this — 
coloration. The youngest tree in which the coloration was present — 
had an age of 72 years, while the youngest tree cut was 52 years old. © 
No attempt can be made to set a minimum age limit for trees with ~ 
purple coloration, since not many trees were cut below the age of — 
70 years. | ia 

Of the 634 trees under consideration, the purple was present in 84 
in which no dry-rot was found. In these the coloration, varying — 
through all shades from a very faint salmon pink to pronounced red- 


DRY-ROT OF INCENSE CEDAR. 28 


dish purple, usually began at the ground level, extending up the heart- 
wood to a minimum height of 2.6 feet and a maximum height of 31.4 
feet. Of these trees 39 had open or healed-over wounds, mainly 
caused by fire, offering or having offered a means of access for the 
dry-rot, but the remaining 45 were without indications of wounds, 
the only possible mode of entrance for the decay being through 
branch stubs. It would be highly improbable that all of these trees 
could be infected by the dry-rot fungus without showing any indica- 
tions of decay, so the conclusion is obvious that purple coloration 
may exist unaccompanied by Polyporus amarus. 

In all, 510 trees with typical dry-rot alone or in conjunction with 
secondary decay were worked up at Sloat, Strawberry, and Crockers 
Station. Notes on 25 of these were incomplete so far as purple 
coloration is concerned, so they drop out of consideration. All but 
17 of the remaining 485 had purple coloration accompanying the 
decay. In certain cases the coloration did not extend over the entire 
decayed area, running out before the decay ended, or else isolated 
pockets of dry-rot were found outside the area of coloration. In the 
17 cases of dry-rot unaccompanied by any coloration, the decay as a 
rule was negligible. In four of these trees, however, there was a loss 
in volume caused by the dry-rot of 7.1, 21.3, 39, and 67 per cent, 
respectively, without any coloration being visible, indicating that 
serious decay can exist apart from the purple coloration. 

Of the 59 infections of the Trametes pini decay, 4 became impos- 
sible of consideration because of incomplete notes. Of the remaining 
55, 12 were unaccompanied by purple coloration, but all of these 
_ except two were very superficial infections. Even in these two the 
amount of cull was very small. This decay had already been shown 
almost invariably to follow wounds in the trees; hence, it becomes 
quite reasonable to presume that the absence of purple coloration 
was brought about in most instances by the change in the physical or 
chemical condition of the heartwood induced by the influence of the 
wounds. 

Where the typical decay and the Trametes pint decay were inter- 
mingled the coloration was almost invariably present, although not 
always throughout the entire infected wood. ‘This was also the case 
with the brown dotlike pockets. However, these data should not be 
judged as more valuable than indications, since the number of cases 
available was relatively few. 

Secondary rots comprised 43 infections; only 12 of these were in 
conjunction with purple coloration. The 31 without coloration only 
yielded one cull case; the amount of unmerchantable volume was 
very small, and furthermore these secondary rots were almost invari- 
ably in connection with healed or open wounds. 


24 BULLETIN 871, U. S. DEPARTMENT OF AGRICULTURE. 


Hence, on account of the failure to find any microscopical evidence 
of fungous action in purple wood, the presence of dry-rot outside the 
area of purple coloration in certain trees, the frequent occurrence of 
extensive coloration in trees free from dry-rot, combined with the 
usual presence of the purple coloration in wood badly enough decayed 
by Polyporus amarus to cause a noticeable reduction in the merchant- 
able contents of the individual tree, while it may be more often absent 
in light infections, the conclusion appears obvious that purple colora- 
tion is not a result of the action of the fungus, but, on the contrary, 
if it bears any relation whatever to the dry-rot, is merely a condition 
of the heartwood inducing favorable development of the vegetating 
hyphe. The fact that the Trametes pini decay is more often unac- 
companied by the coloration is offset by such infections usually being 
superficial and following wounds which probably exert a profound 
influence on the heartwood. No relation was found between the 
purple coloration and the width of the sapwood. Trees with sap- 
wood varying from very narrow to very broad alike had the colora- 
tion in the heartwood. 


RELATION OF DRY-ROT TO AGE AND CONDITION OF THE TREE. 


From previous hints in the literature (22, p. 403-406; 23, p. 520; 
16, p. 18-19, footnotes), Meinecke’s preliminary study on incense 
cedar and his later work on white fir (16), it was reasonable to assume 
that some relation should exist between dry-rot and the age and 
condition of the tree; i. e., the degree of dominance and suppression. 

Minch (22, p. 405), working with artificially infected red beech, 
found suppressed trees more susceptible to decay by Polyporus 
(Fomes) wgniarius, P. (F.) fomentarius, Stereum rugosum, and S. pur- 
pureum than thrifty, dominant ones and explains this by the theory 
that the wood of suppressed trees contains a greater amount of air, — 
consequently more oxygen, than thrifty dominants. In previous 
experiments the same mvestigator (19, 20, 21) had brought out the 
strongly favorable influence of oxygen in the host tissues on the — 
development of wood-inhabiting fungi. Meinecke (16, p. 48) recog- 
nizes three periods in the life of white fir in its relation to the stringy 
brown-rot caused by the Indian-paint fungus (Hchinodontium tine- 
torium): (1) The age of infection, at which ‘‘the infection rarely leads 
to more than negligible decay unless the tree is handicapped by quite 
unusually severe conditions, such as very large old wounds;” (2) the 
critical age, which ‘‘marks the point after which a combination of | 
pronounced suppression and heavy wounding generally results in 
distinct decay;” and (3) the age of decline, ‘‘when even dominant 
(that is, thrifty) trees become subject to extensive and intensive 
decay.” The relation between decay and suppression is brought out. 


DRY-ROT OF INCENSE CEDAR. 25 


The crown class, as determined by observation of the standing 
tree, expresses the past history, more or less strongly modified by 
conditions prevailing through a varying number of years previous to 
the time of observation; it may not give the real past history of the 
tree. “Dominance” and “suppression”’ are really incorrect terms, 
used for lack of better ones. They are based on the relation of the 
height of one tree species to others in the same stand. In this case 
height alone would be misleading. For example, consider a more or 
less second-story species in a mixed stand, in which category incense 
cedar falls. Practically all the trees would be included in the inter- 
mediate or suppressed classes when related to other species in the 
stand, thus entirely obscuring the true relation of the individuals 
within the second-story species. On the other hand, it is an exceed- 
ingly difficult undertaking, often leading to grave error, to attempt 
classification by the observation of individuals in a mixed stand 
with relation to other individuals of the same species. 

For our purposes we can not consider other tree species, but must 
compare individual trees with others of the same species. But here, 
also, height alone is not the deciding factor. Instead of giving 
dominance and suppression in the current meaning, these terms are 
expressed by the relation of the actual volume of the tree to the 
average volume of trees of the same age. Therefore, it was necessary 
to “curve” data collected on a number of trees to secure average 
volumes by age. Only trees of normal form with exact ages and free 
from severe wounds, malformations, and other seriously injurious 
factors which would interfere with the correct computation of the 
volume were used. Curves were constructed for the intermediate 
area and for the optimum area, since it was apparent that the 
volumes by ages would be much higher for the last-named areas 
than for the first, which fact was strongly brought out by the result- 
ing curves. ‘These curves are presented in figure 1, the higher curve 
based on 461 trees representing the optimum area and the lower 
based on 340 trees, the intermediate arca. The National Forests on 
which these areas were located are also indicated. Thence, the trecs 
for the intermediate area and for the optimum area were rated in 
regard to their respective curves, those with a volume higher than the 
average given by the curve for the same age being classed as dominant 
and those with a lower volume as suppressed. At first, an inter- 
mediate group was selected by designating an arbitrary volume above 
and below the average volume, trees between these limits being 
classed as intermediate. However, it was found that such trees 
inclined either toward the dominant or the suppressed in their charac- 
teristics, depending on whether they were above or below the average 
in volume for the same age. Furthermore, it was exceedingly difficult 

182803°—20—Buli, 871—_—-4 


26 BULLETIN 871, U. S. DEPARTMENT OF AGRICULTURE, - 


to determine just what the limits of the intermediate class should be, — 
so in order to preclude any error in judgment the procedure as first — 
stated of establishing just two classes, dominant and suppressed, to 
include all the trees, is followed pheetmhends ‘ 
The method of aieuiniae the volume of the tree in cubic feet 
requires a little explanation. Each tree was considered as a perfect 
cone over the stump, at which the age count had been taken, in 
order to obtain directly comparable figures for the different ages. - 
Figures from normal trees showing the relation of the diameter 
breast high to diameter of butt at stump height (1.5 feet) were plotted 
and curved, the strongest portion of this curve lying between 10 and 
50 inches diameter breast high. From this curve a table expressing 


60 


| CE i 
ZT ee 
40° 60 420 160 200 240 280 320 


A ge - Years 


Fic. 1.—Comparison of average volumes of incense cedar on the optimum and intermediate areas. 


the relation of the diameter breast high to diameter of butt at stump 
height for each inch class was read. It was then a simple matter to 
secure the diameter outside the bark at stump height for any tree, no 
matter how irregular the stump might be, due to wounds or other 
factors, and combining this with the height to work out the total cubic 
contents. Loss of volume caused by wounds or other factors was dis- 
regarded. In other words, each tree was treated as if it was absolutely 
normal, Let it be emphasized again that the volumes obtained were 
not meant to be an exact expression of the actual volume of each 
tree to the last cubic foot but merely had to be directly comparable 
to each other for the various ages. 

In considering the trees with decay, each separate focus of dry-rot 
is termed an infection, and there may be two or more infections in 


DRY-ROT OF INCENSE .CEDAR. OF 


the same tree, each one, however, the result of a separate and distinct 
inoculation. As soon as an infection causes a measurable amount of 
cull it becomes a cull case and is so termed. Hence, every infection 
is not a cull case, but every cull case is an infection. Only loss of 
merchantable timber through dry-rot is considered; cull from 
wounds, knots, limbs, insect borings, or crook is disregarded, since 
these Howe no flee on the loss from dry-rot except when the 
decay is directly traceable to a wound. In such cases loss from the 
wound is included with the volume of rot. 

For figuring from the field notes and measurements the cull caused 
by dry-rot, the amount and degree of damage with relation to the 
resulting loss in merchantable lumber was carefully taken into 
account, just as it is in scaling. For example, a cull case might 
have considerable linear extent but consist only of a few scattered 
pockets in a straight line, resulting in little or no loss n merchantable 
volume. The same number of dry-rot pockets, shorter in linear 
extent but radially scattered thrdughout the heartwood, probably 
would cause considerable cull. Again, a number of pockets close to 
the sapwood, mostly slabbing out when the log is sawed, would have 
far less weight than the same pockets in the center heartwood. 
Meinecke’s method (16, p. 37) of considering the entire bole of the 
tree over the linear extent of decay as cull, while justifiable with the 
commercially inferior white fir, could not be applied to the distinctly 
more valuable incense cedar. Here the lateral extent of the decay 
also had to be taken into account. This could be readily determined 
from the field notes and diagrams. For example, if the decay occu- 
pied one-fourth of the area as seen on cross sections and had a linear 
extent of 10 feet, the volume outside the bark of this 10-foot frustum 
(the tree bemg considered as a cone, see p. 26) was first secured 


and then one-fourth of it was considered as the volume of the decayed 


portion of the tree. Below one-fourth the decay was usually treated 
as negligible except when it had a linear extent of several feet. The 
volume was then computed as before. 

Separate tables contaming the above figures were worked up for 
the four areas, the trees being arranged progressively by ages, begin- 
ning with the youngest. It does not seem necessary to present these 
tables, since they were merely preliminary. 

In considering the trees on the intermediate area it was found that 
the first infection which resulted in cull occurred in a tree 98 years 
old. However, infection can take place at a much earlier age than 


this. For example, in a tree 104 years old there was a light cull case 


traced to a healed lightning wound. The tree was injured at the 
age of 50 years and the wound completely healed when the tree was 
63 years old; hence, the tree could not have been older than 63 years 
at the time of infection. Again, in a tree 146 years old there was a 


28 BULLETIN 871, U. S. DEPARTMENT OF AGRICULTURE. 


serious cull case traced to a healed fire scar. This wound healed ~ 
when the tree was 38 years old; hence infection could not have ~ 
occurred subsequent to that age, since the field notes seem to exclude 
any possibility of an entrance of the dry-rot through a knot. Numer- 
ous other examples might be cited, but none of them reduces the 
minimum age of possible infection below 38 years. 

An analysis of infections definitely traced to healed wounds in 
trees on the optimum area places the earliest age at which trees may 
be infected at 34 years, and this may be accepted as the age of infec- 
tion for all the areas, since there is no apparent reason other than 
chance as to why the various areas should differ in this respect. 
Infections were very common between the ages of 45 and 80 years. 
No tendency was apparent toward an earlier age of infection in ~ 
suppressed than in dominant trees, or vice versa. The foregoing 
figures are based on an analysis of 99 infections. Of course, this age 
may be even lower than here indicated, but it is evident that the 
earliest age of infection can not be lower than the age at which heart- 
wood formation takes place in incense cedar. Just when this occurs 
is not definitely established, but observation seems to place it some- 
where around 20 to 30 years. To be sure, there is a possibility of 
infection taking place in pathological heartwood resulting from an 
injury before the true heartwood is formed, the fungus mycelium 
vegetating in this type of heartwood until such time as true heart- 
wood develops and then attacking it. While absolute proof of this 
course of procedure is lacking, observations have all tended toward 
substantiating the theory. 

Furthermore, this age agrees approximately with that found by 
other workers with different species. Meinecke (16, p. 47) finds 
that for white fir (Abtes concolor) decay caused by the Indian-paint 
fungus (Hchinodontium tinctorium) ‘“‘may show in trees 60 years old 
or perhaps younger,” while Weir and Hubert (32, pp. 17-18), working 
with the same fungus in western hemlock (Tsuga heterophylla), set 
the average infection age for one type at 44.5 years and for another 
at 57.3 years. The figures are obtained by the use of a formula 
applied to the younger age classes. These same workers (33, pp. 
11-12) place the ‘‘age of earliest infection’’ at about 50 years for 
western white pine (Pinus monticola) attacked by several common 
wood-destroying fungi. 

Interesting as the determination of the age of infection or the age 
of earliest infection may be from an academic viewpoint, it is of little 
practical importance in this region. The questions of real import — 
in this as in other species are the age at which decay begins to result 
in cull of economic importance and whether there is any relation — 
between this and dominant and suppressed trees. The trees on the 
intermediate area and on the optimum area were first arranged 


DRY-ROT OF INCENSE CEDAR. 0 29 


by 40-year age classes, grouping dominant and suppressed trees 
separately, and the percentage of dry-rot was determined for each 
age class. This was done by relating the total volume of dry-rot 
in each age class to the total volume in cubic feet of the trees in that 
age class. From these tables it was apparent that while there was 
no tangible difference between the amount of decay in the dominant 
and suppressed trees on the intermediate area, on the optimum area 
there was a decided difference, most strongly shown in the younger 
age classes, the dominant group having a lower percentage of decay © 
than the suppressed trees. 

That the trees in the intermediate area fail to bear out the relation- 
ship between suppression and decay indicated by the results of other 
workers on different species is after all logical. The reason for this 
is not hard to find. ‘These trees are in the intermediate range for 
incense cedar, where the growth on the whole is relatively slow, and 
while they may be placed in dominant and suppressed groups within 
themselves, yet in relation to the trees in the optimum range they 
are slow growing, practically all being included under suppressed, 
with afew dominants. In other words, most of these trees are under 
the influence of regional suppression. Another glance at figure 1, 
which shows the great disparity between the volume-age curves for 
the two regions, brings this out more clearly. The term “regional 
suppression’’ is anew one. However, the concept which it embraces 
has long been advanced in ecology and silviculture. That there is 
a marked decrease in vigor and a decline in the rate of growth for 
each tree species outside its optimum, becoming greater as the dis- 
tance from the region of best. development increases, until finally 
the species becomes completely suppressed by other species either 
in or closer to their own optimum, has been pointed out by Mayr 
(13, pp. 73-79). This is exactly what has happened to incense cedar 
in the intermediate range. At best a second-story tree, in this 
region, away from its optimum, it has become, except for a few 
scattered individuals, badly suppressed by Douglas fir, Jeffrey pine, 
and yellow pine, which, while not in their own optimum, are yet 
closer to such a condition than the incense cedar. Mitchell (17, p. 33) 
recognizes how far this may go in suggesting that it may be advisable 
to eliminate the species entirely on the sites less adapted to it. 

An analysis of the field notes reveals that this regional suppression 
is not due to a pathological condition, which might be suspected from 
the presence of the mistletoe (Phoradendron jumipervnum lbocedri) or 
of the needle and twig parasite (Gymnosporangium blasdaleanum). 

A comparison of the trees on the intermediate area with the volume- 
erowth curve for the optimum area resulted in the classification of 
only 38 out of the total of 495 trees as dominant. In other words, 
457 of the trees on the intermediate area are actually suppressed 
when compared to the average for the optimum area. 


30 BULLETIN 871, U. 8. DEPARTMENT OF AGRICULTURE. 


It is not to be expected that the growth habits of the dry-rot _ 
fungus would vary to any extent in regions so closely related 


climatically as the intermediate and optimum ranges of incense cedar; 
therefore, it is reasonable to believe that no matter what the classifi- 
cation of the trees on the intermediate area may be in respect to 
dominance and suppression when compared with the volume-growth 
curve for that area, to find the true relation of the dry-rot fungus to 
dominant and suppressed trees it will be necessary to determine the 
classification of each tree by comparison with the volume-growth curve 
for the optimum area. 

This is brought out in Table IT, in which the trees from all the areas 
are combined, the dominance or suppression of all the trees being 
determined by comparison with the volume-growth curve for the 
optimum area. Only trees in which the progress of the decay or a 
fire scar did not make it impossible to determine the age at stump 
height are included in this table. This explains the slight dis- 
crepancy between the total number of trees dissected and the total 
number included in this and subsequent tables. 


TaBLE IJ.—Cull caused by dry-rot found in incense cedars of the combined areas. 


Number of trees Cull caused by dry-rot 


Average age. (percentage of the 
has). total volume). 
Age class. 

Dominant. |Suppressed.| Dominant. |Suppressed.| Dominant. |Suppressed. 
Oto 40 yea4rssrs: 2-52. cee ee D> lait ose eer 40“. 2 tage ne eee 0 
Al to'SO)y Carss. = 25% 5.<55-asee- 8 43 74 57 0 1 
Sl pout20 VOars: a. olsen oes ao te 60 125 105 105 4 2 
LAY to 160: Years: 2.) 4<-=yn-4 H-5- 6 66 218 142 140 4 4 
TOECO 200 yarns es ae5 oe = ore 42 191 180 179 7 12 
201.0 '240. yearseie. 5, sees 34 84 223 222 19 26 
Za FO 280KV OATS oc ace = oa ele 15 79 265 258 52 40 

281: tOS20:;VROTS...3 sp 23s Sheps 7 42 301 294 68 
SEL LO SOO Veal stems cee oe ce cee 3 16 341 332 68 66 
361 to 400 vears...--..... eens 2 2 372 368 83 68 

AOL to 440 years: acs sate wee 0 7 hal iN a 436 ||o.-3c cae 
Combined: acc: a seee. eee 237 803 166 173 16 20 


In Table II the dry-rot percentage in the age class 161 to 200 
years, for example, is figured on the total volume of all the dominant 
trees both sound and decayed in that age class and not on the total 
volume of both dominant and suppressed trees. This is the method 
used throughout the table. 

It will be noticed that the number of trees (basis) in the suppressed 
class far exceeds the dominant, this being a direct result of the 
influence of regional suppression on the trees of the intermediate area. 

The columns of greatest interest are the last two, in which the 
dry-rot percentages of the dominant and suppressed trees in the 
different age classes are directly comparable. By dry-rot percentage 


2 


is meant the percentage of cull caused by the decay resulting from 


DRY-ROT OF INCENSE CEDAR. 31 


_ ee 


the work of the dry-rot fungus. The reader should remember that 

the percentage of cull based on the merchantable volume of the trees 

would be higher than the percentages here given, since these are based 

on the total volume of the trees outside bark and including the entire 
: top. In the younger age classes up to 160 years the percentage of cull 
is small and variable, in one class higher in the suppressed, in another 
higher in the dominant, and in a third equal. But in the age class of 
161 to 200 years a decided jump in the percentage of cull occurs, 
particularly in the suppressed trees. While the increase in the case of 
the dominants is only 3 per cent, in the suppressed trees it amounts to 
8 per cent, bringing the cull percentage to 12. In the next age class 
a still further change is apparent. Here the cull percentage in the 
dominant trees increases strongly, as does also the percentage in the 
suppressed trees, the latter still remaining considerably higher than 
the former. But in those subsequent classes which have a sufficient 
numbers of trees to make the data of value, the cullis higher in the 
dominant than in the suppressed trees. When the age classes are 
combined, the total cull is 4 per cent more in the suppressed than in 
the dominant trees. — 

The salient features shown by Table II are the low percentage of 
cull in the younger age classes, the sudden increase earlier in the 
suppressed than in the dominant trees, which after it once begins goes 
steadily on with advancing age, and the higher percentage of cull in 
the suppressed trees as compared with the dominant trees in the two 
age classes which show the first sudden increase in this percentage. 

However, the percentage of cull caused by dry-rot is not the only 
figure of interest, since it is prerequisite that the trees first be infected 
and that these infections develop sufficiently to cause measurable 
cull. Table III gives the figures on percentage of infection and cull - 
cases. The number of trees used as the basis and the average age 
are the same as in Table II. 


—" — . SS << 


ti el i te es a i ee —_" _—- | _ —_ 


TaBLeE II1.—Jnfections and cull cases found in incense cedars of the combined areas. 


Infections (percentage | Infections causing meas- 
of total number of urable decay (percent- 


retinas: trees). age of total cullcases). 

Dominant. |Suppressed.) Dominant. |Suppressed. 

SS Sar ee | BE crit hte Oui ee sien ae. oo 0 
INUICMIMMRIERA! Sti a2. SOS. -\2 25008 sen kt Fee Salsa abel 12 5 0 5 
oui UU) SCO oe ae on ae as a 50 33 28 15 
REGIS 2058 Maras 28 9 18 2 ek ae 62 42 35 28 
Se ee, ee ; 57 62 36 44 
RS ES 822 Pe ee eee 71 74 56 63 
SE ee ae eee ee a 87 82 80 78 
MME MAGES: (2c GA. Soci. ao Sav ee eee el eee bbe eebe. 100 90 86 88 
321 to 360 years. .-.-.. US pL Gao ie Ob SH SSE ane 100 87 100 87 
UE GRE AAS SEE eee eee ee 100 100 100 100 
IN 905 yo ad | SL ie PES eee LCR aaa 100 


Combined... ... See I 61 54 41 42 


32 BULLETIN 871, U. S. DEPARTMENT OF AGRICULTURE. 


Table III shows that the percentage of infections is not in exact 
relation to the percentage of cull caused by dry-rot as given in Table 
II. In the age class of 41 to 80 years, while the percentage of 
infections is higher in the dominant trees the percentage of cull is 
slightly lower. In the age class of 81 to 120 years these percentages 
bear the same relation to each other as they do in all other classes 
-except the classes of 121 to 160 years and 361 to 400 years. In the 
former there is a much higher percentage of infections in the dominant 
trees, while the percentage of cull is equal, and in the latter the per- 
centage of infections is the same in both dominant and suppressed 
trees, while the percentage of cullis higher in the former. For all the 
age classes combined the percentage of infections is markedly higher 
in the dominant than in the suppressed trees. 

Now, considering the columns relating to the total trees with cull 
cases, that is, where infections cause a measurable amount of decay, 
it is found that in the age class of 41 to 80 years none of the infections 
in the dominant trees result in cull cases, while all of the infections in 
the suppressed trees do, thus accounting for the higher percentage of 
cull in the suppressed trees in that class. In the next age class (81 
to 120 years) the dominant trees have almost twice as many cull cases 
as the suppressed, and the percentage of cull is just twice as great in 
the former. But in the age class of 121 to 160 years, while the cull 
cases are in a higher percentage in the dominant trees the percentage 
of cull is equal in the two classes, showing that there is more loss per 
cull case in the suppressed than in the dominant trees. In the subse- 
quent age classes the cull cases and the percentage of cull are in the 
same general relation except in the age class of 361 to 400 years, 
where the difference is the same as explained for the infections. ‘The 
total cull cases for the suppressed trees is only 1 per cent higher than 
for the dominant trees. 

The idea might have been advanced that since inoculation by 
spores of any wood-destroying fungus is to a certain extent a matter 
of chance, the greater percentage of cull in the suppressed trees might 
have been due to a greater number of infections in these trees. But 
Table III shows more infections in the dominant trees, while the cull 
cases are about equal in both. Therefore the cull cases must be 
more severe in the suppressed trees. 

The infections, or even the cull cases, do not show the same pro- 
gression through the age classes from he youngest to the oldest as is 
shown by the cull percentage. In the former the sudden, sharp 
increase in the age class of 161 to 200 years for the suppressed and in 
the class of 201 to 240 years for the dominant trees is not apparent. 
The increase is more regular throughout, thus indicating that there 
is an influence other than merely the number of infections which has 


DRY-ROT OF INCENSE CEDAR. 33 


a strong bearing on the development of cull cases and the percentage 
of cull. 

Since neither the total number of infections nor cull cases follows 
the same law as the percentage of cull, it is self-evident that there 
must be an exact relation between this last and the more extensive 
or severe cull cases. Accordingly, in Table IV the severe cull cases, 
that is, those cases in which one-third or more of the total volume of 
the tree is a loss through dry-rot, are considered separately. The 
same basis is used as in Tables If and III and the percentages are 
based on the number of trees in the dominant and suppressed groups 
considered separately in each age class. 


TaBLE 1V.—Relation between dominant and suppressed trees in severe cull cases found in 
incense cedars of the combined areas. 


Severe cal eae (per : Severe cull cases (per 
cent). 
Age class. 5 Age class. 

Dominant. | Suppressed. Dominant. |Suppressed. 
One MO Weats ree eean cic. -|.2---2>-L-..- 0 || 281 to 320 years..........- 71 66 
AITO SOVVCars. 2. o5022-..-2 0 0 || 321 to 360ryears........... 67 81 
Sito 20;yeats...2.--.-.... 3 2 || 361 to 400 years..........- 100 50 
12P Tomooryearsx.. -......-. 2 241 P401NC O44 O-Viearssons 2. see | 205 SS S228 100 
161 to 200 years............ 5 14 Ss eee 
201 to 240 years...........- 26 31 Combined.........- 14 | 17 

241 to 280 years..........-. 73 48. | 

| 


In Table IV is seen the same form of progression for the severe cull 
cases as was shown for the amount of cull in Table II. Low per- 
centages in both groups up to an age of 160 years, with a sudden 
increase in the percentage of severe cull cases in the age class of 161 to 
200 years for the suppressed group are followed by a like increase in 
the class of 201 to 240 years for the dominant trees. After 240 years 
is passed there is a higher percentage of severe cull cases for the sub- 
sequent age classes in the dominant group, just as is the case for the 
percentage of cull. The only exception to this is found in the class of 
321 to 360 years, where the relation is reversed. 

The outstanding fact shown by Tables I, ITI, and IV is that incense 
cedar during the earlier stages of its life, even though heavily infected, 
is able to retard the progress of the dry-rot fungus in causing decay. 
Then comes a period, earlier in the case of suppressed than of domi- 
nant trees, at which the progress of the fungus can no longer be held 
in check and the trees become subject to severe decay, with the accom- 
pahying high percentage of cull. In other words, the decay becomes 
extensive. This period occurs in the age class of 161 to 200 years in 
the suppressed group and in the age class of 201 to 240 years in the 
dominant group. An analysis of the individual trees, in a table which 
is too long to present here, reveals the fact that this change begins at 
167 years in the suppressed and at 214 years in the dominant trees, 


34 BULLETIN 871, U. S. DEPARTMENT OF AGRICULTURE. 


At these ages extensive decay, as represented by severe cull cases, 
becomes common in the individuals of the respective groups. These — 
ages, using Meinecke’s nomenclature, may be termed the ‘critical — 
age’’ and “age of decline” for incense cedar—that is, the ages at 
which suppressed trees and dominant trees, respectively, become — 
subject to extensive decay. Meinecke found a combination of severe — 
wounding and pronounced suppression both contributing te the criti- 
cal age in white fir, but in incense cedar wounding is not necessarily 
afactor. This will be brought out later when mechanical injuries are 
considered. 

After the age of decline is passed, as shown by the percentage of 
cull in the classes older than 240 years, the dry-rot is more extensive 
in the dominant than in the suppressed trees. This means that 
while the dominant trees are able to ward off the extensive develop- 
ment of the dry-rot fungus for a longer period than the suppressed 
trees, after the age of decline is once passed dominance ceases to be 
a factor in resisting decay and, in reality, seems to favor it. This 
may be due to the fact that in the old, overmature dominant trees 
there is a higher percentage of food material (i. e., heartwood) for 
the fungus to work on in relation to the total volume than in the 
case of the suppressed trees. The fungus does not attack sapwood. 

Let us consider what the foregoing paragraphs mean from a prac- 
tical standpomt. Roughly, we may place the critical age at 165 
years and the age of decline at 210 years. This does not mean that 
there is no loss from decay previous to these ages, or even that 
there are no severe cull cases; but the latter are so rare, as shown by 
Table IV, that they may well be regarded as exceptions. Since all 
but a very few of the trees on the intermediate area are suppressed, 
taking this area as representative for the intermediate range we 
can not expect trees within this range to remain free from extensive — 
dry-rot after they have attamed the age of 165 years. In the opti- 
mum range this same age may be set for suppressed trees, while 
dominants will remain relatively sound until the age of 210 years is 
reached. On the optimum areas dominant individuals comprised 
36.5 per cent of the total, but on the intermediate area only 7.6 per 
ceir.“)*s : 

No relation was found between diameter breast high and dry-rot. — 
This could hardly be expected, considermg that mcense cedar is a ~ 
tolerant species In an uneven-aged mixed stand. | 

In Tables IT, III, and IV the comparison of the dominant and sup- 
pressed trees in their relation to the percentage of cull due to dry-rot 
has been emphasized to the neglect of other considerations in which 
the same relation might be found in both groups. In Table Vmany _ 
of the data given previously but separately for the dominant and 
suppressed groups are combined. | 


DRY-ROT OF INCENSE CEDAR. 35 


TABLE V.—Combined data relating to dry-rot found in incense cedars of the combined areas. 


Percentage of— 


Average | Number 
Age class. age of trees 


g 2 - 
(years). | (basis). Dry-rot | Severe Cull Infec 


volume. cull cases. | tions. 
cases. 

SENET ORES ea rece. cde e ds. oes s ec eee ceeek 40 1 0 0 0 0 
OOD DS ee a 60 51 1 0 4 6 
MINED EPDU OAR GE Sod ads oben koe ee ee te oe oe ee ; 105 185 3 3 20 38 
PMI MUEMORES ciated co .d oac 200s abn -- Fao See anie 141 284 4 2 29 46 
MG EOLN VeRUSenn sda kes ot ec eek lee ee ese 180 233 10 12 42 61 
(AD eve )S5 CE eS a nr 223 118 22 30 61 iis 
BEET IEL OIRO MV OOTS= ojoiaeia cic at « oo -- 5-0-5 -- nas. ees 259 94 44 52 79 83 
oo a Oe re 296 49 62 67 88 92 
eISUGRMOMORTS hy soascck fk li. ere ces 334 19 67 79 90 90 
LOO On 370 4 82 75 100 100 
CL a 2B OS SEE eS ee ee 436 2 D 0 100 100 
COTS 3 G0") 2 aS Se ee ees 171 1,040 18 17 42 56 


Table V strikingly demonstrates the cumulative risk to incense 
cedar from dry-rot with advancing age. Starting at 1 per cent of 
cull in the age class of 41 to 80 years it mounts to 67 per cent in 
the class of 321 to 360 years. With a very gradual increase up to 
160 years it then becomes rapid. The figure of 82 per cent in the 
class of 361 to 400 years, even though on an insignificant basis, is 
not without significance when considered in relation to the general 
previous progression. ‘That this figure should drop to 5 per cent in 
the last age class need not cause concern, since the basis is only two 
trees. Even though infected, a tree may escape extensive decay 
throughout its life. This is a rare occurrence, however. The percent- 
age of severe cull cases closely follows the percentage of cull throughout 
until the last two age classes with their small bases are reached. 
These two sets of figures show beyond doubt the high percentage of 
loss through dry-rot that may be expected in overmature cedars and 
clearly prove that the presence of such trees in our stands of the pres- 
_ ent and the future can be nothing but an economic loss. 

That the percentages of cull cases and of infections do not follow 
the same form as the two others just discussed was shown in previous 
tables, but is more clearly brought out here. The reasons for this 
_ have been touched upon. However, these two figures are of interest 
when compared. It is seen that with advancing age the percentage 
of cull cases becomes increasingly higher at a more rapid rate than 
does the percentage of infections, until finally in the class of 321 to 
360 years the two coincide. To be more explicit, the infections 
gradually begin to cause more and more measurable decay, until 
finally every infection has resulted in a cull case, no matter how slight. 
In the last two age classes both cull cases and infections have reached 
100 per cent; but again we are confronted by the small basis and this 
figure can not be accepted. There is no doubt that a tree by rare 
chance may escape infection throughout its life, but there is hardly 


36 BULLETIN 871, U. S. DEPARTMENT OF AGRICULTURE. 
any possibility that when once infected sooner or later some cull 
will not result. _ 

To make the relation just discussed even more apparent the 
four sets of data have been plotted in figure 2. From this, it can 
be seen that the form of the curves for severe cull cases and cull 
are the same, but differ quite markedly from the curve for infections. © 
This shows clearly that infections alone are not the sole influence 
on the development of the dry-rot fungus, for if so the curves would 
have the same form. The slow progress of the dry-rot in the younweayy ; 
trees is very apparent. 

The curve for the cull cases is somewhat intermediate, at first 
inchning toward the severe cull cases and later coinciding with the — 
infections, The younger trees are able to retard the fungus suffi- | 


1 heal 
ine HA en 
At 


Per cent 
ray 


Se ee 
Age - Years 


Fia@. 2.—Relation of the age of incense cedar trees to infections, cull cases, severe cull cases, and cull, 


ciently to prevent many of the infections from developing into cull 
cases, but later this characteristic is obscured. 

The relative percentages of cull due to dry-rot on the various © 
areas is not of importance from the standpoint of the present inves- 
tigation. That this will vary widely even within the optimum and — 
intermediate ranges is self-evident to anyone who has been on ~ 
logging operations where incense cedar is being cut. At times the © 
variation, even in localities quite close to each other, is surprising. : 
On the intermediate area the cull for all the trees amounted to 20.5 — 
per cent, while for the optimum area the figure was 16.8 per cent. 
These figures must not be taken as absolute, since it must be remem-— 
bered that the areas were not clear cut. Practically every tree 
between the ages of 100 and 240 years was cut except those in which — 
it was apparent that the age could not be accurately determined. — 
Not all the trees below 100 years or over 240 years were cut, how- 


ever, since this would have meant an enormously increased cost 
hi i 


DRY-ROT OF INCENSE CEDAR. 837 


without adding much to the investigation, the chief aim of which 
was to determine the age at which dry-rot became extensive and 
far-reaching. However, the relative representation of trees in the 
older age classes was maintained as far as possible, neglecting 
entirely, of course, the few very old veterans always found scat- 
tered through a virgin stand. 

The cull percentages given are indicative of the relative condi- 
tions that will exist in the intermediate and optimum ranges, 
although stands in the latter will on the whole be relatively more 
free from dry-rot than our figures indicate. However, the Office 
of Forest Pathology is now collecting figures for cull percentage 
by a less intensive method over various localities, and these will 
include not only cull due to dry-rot but to all other causes as well. 

Before drawing final conclusions there is one other factor which 
must be considered in relation to dry-rot, namely, wounds or 
mechanical injuries. 

MECHANICAL INJURIES. 


The mechanical injuries which must be reckoned with are those 
caused by fire, frost, lightning, and the breaking off of branches 
as well as such miscellaneous factors as snow, falling trees, mammals, 
and wind. These injuries are important from three standpoints. 
First, they often afford an entrance to the heartwood of the tree for 
spores of wood-destroying fungi; next, the growth processes of a 
tree may be somewhat interfered with, resulting in a lessening of 
increment and a consequent tendency to suppression; and, last 
and least important, an actual loss in merchantable volume may 
result from the mere presence of the injury. 

Spores of the dry-rot fungus (Polyporus amarus) must have an 
entrance to the heartwood before they can germinate and develop. 
As long as the tree is protected by a layer of bark and sapwood it 
is immune from the ravages of dry-rot or any other heartwood 
destroyer. Small superficial wounds are quickly protected by 
resin exudation from the bark, which forms an antiseptic dressing 
on the wound, safeguarding it from fungous spores until the wound 
is finally healed or callused over. But incense cedar is poorly 
supplied with resin. Normally it is found in a limited quantity in 
the bark only, active in the inner bark, dry and hard in the outer 
bark. Large superficial wounds may often prove tobe serious. 
If the bark is torn off over a large surface there is not enough resin 
available to form a dressing, the sapwood dries out and cracks into 
the heartwood, and these cracks offer an entrance for fungous spores. 
The most serious type of wounds, of course, are those extending 
deep into the heartwood, for then the heartwood is directly exposed 
to infection by wood-destroying fungi for the entire period of time 


38 BULLETIN 871, U. §. DEPARTMENT OF AGRICULTURE. 


from the occurrence of the injury until it is completely healed over, 
and such injuries heal slowly. Wounds heal much more rapidly 
in young than in mature or overmature trees. 

The causes of wounds are taken up in the order of their importance. 


FIRE. 


The most serious wounds, both numerically and in regard to 
the type of injury, result from fire. It is almost impossible to find 
a stand of timber anywhere in the Sierra Nevada or Coast Ranges 
which has not been visited by repeated fires. While the thick 
bark characteristic of incense cedar combined with the lack of 
resin in the wood makes it somewhat fire resistant, yet broad fire 
wounds commencing at ground level, reaching some distance up 
the trunk, and extending deeply into the heartwood are very fre- 
quent. These wounds are usually roughly triangular in shape, 
the base being at ground level and the apex at the top of the extent 
of the scar on the tree trunk, Considerable loss in merchantable 
timber results from the actual destruction of the wood, and there 
must be an appreciable decrease in increment until the tree read- 
justs itself to the loss in conducting tissue caused by the partial 
destruction of the sapwood and inner bark, which interferes with 
the conduction of water and soluble salts from the roots to the 
foliage and the return of elaborated food from the foliage to the 
roots. This loss is exceedingly difficult to gauge. Total .loss in 
the merchantable timber occurs when a tree is completely girdled 
and killed or when the supporting tissue is so weakened by the 
wound that the tree is blown down. , 

Large fire scars or ‘‘catfaces’’ are rarely caused by only one fire, — 
but usually by successive fires, each one hollowing out the heartwood © 
a little more. As many as 10 distinct fires have been found con- 
tributing to the formation of one catface. As long as the wood is 
completely covered by a charred surface the danger of inoculation by 
fungous spores is reduced to the minimum, but the wood dries out 
and checks, forming cracks extending into the unburned wood. In ~ 
time, the charred surface is weathered away, and finally the heart- 
wood is exposed over the greater surface of the catface. Here is offered 
an excellent place for the entrance of a heartwood-destroying fungus. 

Wounded trees make strong efforts to callus over the injury, and 


this is often accomplished in course of time if the wound is not too 4 


large. Very large catfaces, particularly on mature or overmature 
trees, are rarely healed over. The prevalence of wounds caused by 
fire may be seen from Table VI. 4 

Table VI clearly shows that fire injury was much more serious on _ 
the intermediate area than on the optimum area. The columns of — 
greatest interest are the third and last. The third column (per- — 


DRY-ROT OF INCENSE CEDAR. 3 89 


centage with open fire scars) shows that of the total number of trees 
analyzed on the intermediate area, 38.3 per cent had open fire scars, 
while on the optimum area the percentage is only 23.5. In other 
words, these percentages of the total number of trees cut on the 
areas under consideration were still exposed to infection by wood- 
destroying fungi through fire scars alone. The last column indicates 
that 72.2 per cent of the trees on the intermediate area and 49.3 per 
cent of those on the optimum area have had open fire scars at some 
period of their life history, thus exposing them to moculation by 
fungous spores. 


TaBLE VI.—Incense-cedar trees found in the combined areas having fire scars. 


Trees with fire scars (per cent). 


Number 
Locality. ch trees nei 
asis). iscella- 
Open. | Internal. | “jeous.1 | Total: 
| Br 
ee ee | 509 38.3 33.2 0.8 72.2 
RON asISATIRTAE ON ee Se ed ee ne se ce ce de 566 23.5 25. 4 4 49.3 
ES sewer teak? Ot Lf, 1,075 30.5 29.1 5 60. 1 


1 Includes wounds probably but not certainly caused by fire. 


The internal scars on the intermediate area exceeded those on the 
optimum area by less than 8 per cent, but there were 15 per cent more 
open scars. This points to the fact that the intermediate area has 
been visited by more serious fires than the other, since, as has already 
L en pointed out, large catfaces are normally the result of repeated 
fires. | 

The combined figures for all the areas show that a total of 30.5 
per cent of the trees had open fire scars, while 60 per cent suffered 
fire injury at some time. The column headed ‘‘Miscellaneous”’ in- 
cludes trees with scars not identified beyond all doubt as having been 
caused by fire. These are so few that they need not enter into the 
interpretation of the figures. 

FROST. 


Frost causes some injury in incense cedar but is not nearly as serious 
in this respect as fire. Frost cracks as a rule extend for some dis- 
tance up the tree and go deeply into the heartwood. A common place 
for the cracks to commence is just at the apex of an open fire scar, 
apparently a point of weakness in the tissues of the wood. Often 
they are somewhat spirally twisted around the trunk, distinctly 
reminding one of typical lightning scars. While frost cracks present 
only a very narrow opening for the entrance of fungous spores, yet 
in length those cracks or clefts are often quite extensive. Jn many 
cases the wood around a frost crack is badly discolored, causing 
considerable loss in the merchantable contents of the tree. 


40 BULLETIN 871, U. S. DEPARTMENT OF AGRICULTURE, 


Typical frost cracks are rarely found except on large trees. Table 
VII shows the percentage of frost cracks on the trees analyzed. 


TaBLE VII.—IJncense-cedar trees found in the combined areas having frost cracks. 


Trees with frost cracks 
Number (per cent). 
Locality. cs ad) 
asis). ; 
Open. |Internal.| Total. 


| |] | 


NITberineCAvE Area. . oc acc coe wee eee ee ne eee ee 509°] 4a 3.14 7.26 
Optimum area: -: so05 4... Resdbes 2) eee See ee ee eee 566 1.41 53 1.94 


Combined s «fc sucess UE ae eee eee eee 1,075 2.70 La 4.47 


Here again, as in the case of fire, the wounding is worse on the 
intermediate than on the optimum area. The percentage of trees 
exposed now or in the past to inoculation by fungous spores through 
the medium of frost cracks is rather low and not of great importance 
on any of the areas. Frost cracks in incense cedar are not nearly so 
prevalent as Meinecke (16, p. 31) found for white fir. 


LIGHTNING. 


Incense cedar suffers only slightly from injury by lightning. This 
is to be expected, since the dominant species in a stand and as such 
the taller trees (25, p. 36) are most subject to lightning stroke, while 
incense cedar rarely attains this position in the mixed stand in which 
itisfound. Plummer (25, p. 33) also shows that incense-cedar wood 
is a poor conductor of electricity. 

An incense-cedar tree in the forest badly shattered ee lightning © 
is an exceedingly rare sight and immediately provokes comment. 
However, trees with slight lightning injuries are more common. 
Such injuries show as superficial wounds on the trunk. Often the 
wood is not scarred, but the bark and cambium are killed. The 
bark then drops away, exposing the sapwood, which in turn dries 
out and checks, offering fungous spores access to the heartwood. 
Long wounds extending spirally around the tree, so common in white 
and red fir in this region, are an unusual occurrence on incense cedar. 

Table VIII indicates the prevalence of lightning scars. 


TaBLeE VIII.—Incense-cedar trees found on the combined areas having lightning scars. 


Trees with lightning scars 
Number (per cent). 
Locality. a aise 
asis). 
Open. | Internal.| Total. 


Intermediate area’. ¢ (2. een ee ee ee ee 509 1.76 2.50 4.31 
Optimiumiarea... 2 ee Be ee ee 566 3. 54 1.06 4.60 


a a el , 


Combined. <<... si Seek to a 1,075 2.70 1.77 4.47 


DRY-ROT OF INCENSE CEDAR. 41 


Besides the trees shown in Table VIII, there were seven on the 
intermediate area and five on the optimum area with slight wounds 
which appeared to have resulted from lightning; but an absolute 
determination was impossible. The meager basis in this table shows 
practically an equal number of lightning-scarred trees in the two 


localities. 
BREAKING BRANCHES. 


Incense cedar does not prune itself easily even when growing in a 
dense stand, a fact attested by the persistence of the lower limbs. 
In time, however, some of the lower branches die and break off. The 
dead stubs then offer a point of entrance for heartwood-destroying 
fungi; the spores lodging in the dead wood may germinate, develop, 
and the fungous hyphe pass through the bark and sapwood of the 
tree into the heartwood by way of the pin knot. The pin knot in 
this case plays exactly the same réle as an open wound, but it must 
be remembered that the area for lodgement of a fungous spore on a 
pin knot that is not healed over is exceedingly small in comparison 
with other types of wounds. On the other hand, there are normally 
from several to many open pin knots on each tree, and every tree, 
throughout all but the earliest years of its life, is thus exposed to 
inoculation by fungous spores through these open pin knots. Many 
of course heal over, but others take their places. 


OTHER CAUSES. 


Besides the causes of wounds eS discussed, there are a few 
others of minor importance. 

Strong winds will occasionally break off branches or tops, or over- 
throw entire trees, particularly those weakened by a bad open fire 
scar in the butt. The thick foliage of incense cedar collects a very 
heavy weight of wet snow, often causing the tops and branches of 
young trees especially to break off. Sometimes a falling tree will 
rake off the limbs and part of the bark of a neighbor. Such injuries 
are usually superficial unless very large branches have been broken 
off or the bark has been torn away from the trunk over a considerable 
area. 

Man is at times directly responsible for certain wounds. It is quite 
a common sight along a newly constructed road to see bark torn off, 
often rather high on the trunk, where the tree has been struck by a 
flying rock from a powder blast. Some wounds result from blazing 
trees to mark a boundary line or trail, but they are usually small and 
rapidly heal over. 

Broken or dead tops, the cause of which is often impossiblé to 
determine, are not at all rare. Trees with these injuries comprised 
6.9 per cent of the total number on the intermediate area and 7.1 
per cent on the optimum area. 


42 BULLETIN 871, U. S. DEPARTMENT OF AGRICULTURE. — 


PREVALENCE OF INJURIES. 


Most incense cedars do not attain any great age or size without 
suffering some injury. Many old trees, and more rarely young ones, — 
show numerous injuries, often fire, frost, and lightning having com- — 
bined in the wounding of a single tree. Of the 509 trees on the 
intermediate area only 116, or 22.8 per cent, escaped without injury, — 
while on the optimum area 38.9 per cent, or 220 of the total 566, were — 
free from wounds. This difference is explained by the fact that the — 
risk from injury has been greater on the intermediate area than on 
the optimum area, while a greater number of young trees were cut 
on the last-named area than on the first. The risk of injury is — 
cumulative, increasing with the age of the tree. 

This cumulative risk of wounding is shown clearly in Table IX, 
in which the trees from all areas are combined and arranged by 40- 
year age classes. Only those trees the ages of which it was possible 
to determine exactly are included in this table, while the data on 
wounds previdusly presented include all the trees. This accounts 
for the apparent slight discrepancy between the figures on the total 
number of trees involved. 


TaBLE IX.—JIncense-cedar trees showing cumulative wounding in the combined areas. 


Trees Trees 
with with 
Total severe Total severe 
Number} with wounds Number| with wounds 
Age class. of trees | wounds | (percent- _ Age class. of trees | wounds | (percent- 
(basis). (per age of (basis). (per | ageof 
cent). total cent). total 
wounds). | wounds). 
1 2 3 4 | 1 2 3 4 
0 to 40 years........- 1 0 0 281 to 320 years..... 49 98 62.5 | 
41 to 80 years........ 51 29.4 6.7 || 321 to 360 years..... 19 100 68.5 
81 to 120 years......- 185 48.6 14.4 || 361 to 400 years..... 4 100 100 
121 to 160 years...... 284 59. 2 28.6 || 401 to 440 years..... 2 100 50 
161 to 200 years....-- 233 74.3 35. 2 = |_ ——— 
201 to 240 years...... 118 82.2 44.4 Combined.... 1, 040 67.6 36.3 
241 to 280 years...... 94 92.6 43.6 
J 


In considering the figures in Table IX the reader should keep in 
mind the fact that since branch stubs are not treated as wounds, 
wounded trees practically mean fire-scarred trees, as the number of 
~ wounds from causes other than fire have been shown to be insig- 
nificant. 

Considering column 3, which expresses the ratio of the wounded — 
trees to the total trees, it is seen that the trees are subject to con- 
siderable wounding at a very early age and that this percentage 
increases very rapidly, until in the older age classes every tree has 
been wounded and consequently at some time exposed to infection. 


DRY-ROT OF INCENSE CEDAR. 43 


Not only does the total number of wounds increase with age in a 
stand, but the number of severe wounds becomes proportionately 
greater. Each tree was given a wound rating (x), x, xx, or xxx, the 
first symbol indicating very slight wounding and the last very | 
severe. In Table IX trees with a rating of xx or xxx are con- 
sidered as severely wounded. In all cases the character as well 
as the extent of the wounding and its relation to inoculation by 
spores of the dry-rot He se was carefully taken into account in 
applying the rating. 

In column 4 of Table IX it is seen that while in the age class of 
41 to 80 years only 6.7 per cent of the wounded trees are severely 
wounded, an almost steady increase brings this figure to 68.5 per 
cent in the class of 321 to 360 years. This is to be expected, espe- 
cially since fire scars predominate, because large scars of this type 
are almost invariably the result of recurring fires, and in the past 
virgin stands “in California have been fire swept time and again. 
The two oldest age classes can not be given much weight, owing to 
an insignificant basis. 

The above figures demonstrate the rather slight chance an incense 
cedar has of rounding out its life without a reduction in its normal 
increment through an injury interfering with the growth processes 
or a reduction in its actual content of merchantable timber, either 
directly from a wound or by a wound affording an entrance for a 
heartwood-destroying fungus, in this instance most probably the 
dry-rot fungus (Polyporus amarus). 


RELATION OF DRY-ROT TO MECHANICAL INJURIES. 


The intimate connection of various kinds of wounding, especially 
fire, with infection by the dry-rot are shown in Table X. The 
infections are grouped under their respective causes and percentages 
for each cause, figured on the basis of the total number of infections. 
Trees of uncertain ages are included in these figures, since it makes 
no difference in this table whether or not the absolute age of the 
tree is known. 


TaBLE X.— Mode of entrance of dry-rot infections of incense-cedar trees. 


Means of entrance of infections (per cent). 


ae aha 
Locality. qe rats Wounds 
tions Fire tise Light- Un- Frost | Broken 
(basis). ace Knots. cine ning | known racks. |. o dead 
| ster’ known, | SCars- | causes. ‘| tops. 

Intermediate area.......... iahTE VBR? |i WE. Bi 98 0.6 2.5 0.9 0.6 0.3 
Opiamum area. .....-..-..... 334 58.7 31.1 5.1 1.5 2. 4 9 3) 
Combined.............. | 656 | 67.1| | 25.3 2.9 2.0 1.7 8 Zs 


44 BULLETIN 871, U. S. DEPARTMENT OF AGRICULTURE. 


Table X shows that on the intermediate area nearly 76 per cent 
of all the infections entered through fire wounds; this means of 
entrance for the optimum area is approximately 59 per cent, while — 
for all the areas combined it is almost 70 per cent. Since fire scars 
are almost invariably found in the base of the tree, commencing at — 


ground level, these figures are at variance with Von Schrenk’s (26, — 


p. 69) idea that ‘‘the decay begins somewhere in the upper part of a 
tree.” , 
Besides fire wounds being responsible for such a high percentage 
_ of the infections, inoculations through wounds of this character 
quite commonly lead to very serious and damaging dry-rot, even 
in some of the younger trees. In many cases, even in old trees, a 
long continuous pocket of dry-rot, sometimes having a linear extent 
of 10 feet, will follow a healed fire scar, running out at the end of 
the wound, with no further decay extending up the tree. Such 
infections do not appear especially serious, but it must be remembered 
that the most valuable portion of the trees, the heartwood in the 
butt log, is damaged. On the other hand, the fungus evidently 
finds conditions highly unsuitable in the wood back of a large open 
fire scar. Almost every tree with this type of wound appeared 
sound on the stump when felled, but serious dry-rot appeared at 
the first cut above the open fire scar. When such logs were split, 
it was found that the pockets of dry-rot commenced just at or a 
little above the top of the open fire scar, but rarely lower down. 
The avoidance of the dried-out wood around an open fire scar by 
the mycelium of this fungus is not at all in keeping with the results 
of experiments of Minch (19, 20, 21), which emphasized the highly 
favorable influence of an increase in oxygen coupled with a decrease 
in moisture in the host tissues on the development of various wood- 
inhabiting fungi. There should certainly be a big increase in the 
oxygen content of heartwood directly exposed to the air over that 
protected by a heavy layer of bark and sapwood, thus, according to 
Miinch’s theory, causing very serious dry-rot in the wood around 
open fire scars. The exact reverse of this is the condition actually 
existing. However, every wood-inhabiting fungus must have cer- 
tain minimum physical requirements for its growth and development. 
Possibly the dried-out wood in this case falls below the minimum 
water requirement of Polyporus amarus, or it may be that certain 
chemical changes in the wood brought about by more or less ex- 
posure to the air inhibit the growth of the fungus mycelium. 

Not every fire scar is inoculated, but the chances for inoculation 
with subsequent infection are rather high, owing to the relatively 
large area of heartwood exposed offering a broad surface for the 
lodgment of spores of the dry-rot fungus. On the optimum area, 
70 per cent of the trees wounded by fire subsequently became infected, 


DRY-ROT OF INCENSE CEDAR. 45 


on the intermediate area 64 per cent, and on the combined areas 67 
per cent. The percentage of risk of a tree with a fire scar becoming 
infected is very high. 

Next in importance to fire scars as a means of entrance for dry- 
rot come knots. Of the infections on the intermediate area 19 per 
cent entered in this way and 31 per cent on the optimum area, while 
for the areas combined the figure is 25 per cent, a little more than 
one-third as many as were traced to fire scars. The greater part of 
such infections, because they rarely extend beyond the wood of the 
knot itself, are of little or no importance as compared with fire scars 
in promoting serious cull. Of the total infections entering through 
knots only 48 per cent resulted in cull cases and 12 per cent in severe 
cull cases, while in infections through fire scars, 80 per cent of the 
total became cull cases and 38 per cent severe cull cases. The above 
data were at first tabulated by 40-year age classes, but this brought 
_ out nothing of importance. In the case of infections through fire 
scars most of them developed into cull cases in every age class; 
while for infections through knots up to 200 years less than half 
developed into cull cases, but beyond that age the cull cases became 
more numerous. 

Considering all the severe cull cases as 100 per cent, it is found 
that fire is responsible for 84 per cent, knots for 10 per cent, and all 
other causes for the remaining 6 per cent. Furthermore, 81 per 
cent of the total volume of cull caused by dry-rot resulted from 
infections entering through fire scars. This demonstrates the 
serious réle played by fire in connection with dry-rot. Fire scars 
are responsible for by far the greater number of infections, and a 
high percentage of these infections results in severe cull cases. 

Knots are of some importance, though, in promoting severe cull 
cases throughout the life of the trees, even in the younger age classes. 
For example, of the fourteen severe cull cases occurring in all the 
trees up to 165 years of age, four entered through knots. - 

Of course, every tree is exposed to infection in this way throughout 
all except the very earliest years of its life, not only at one but at 
several points, since each tree usually has from several to many open 
knots or branch stubs, whose dead wood offers a bridge for the 
fungus from the outside through the bark and living sapwood into 
the heartwood. However, each knot presents only a very small 
surface for the lodgment of spores of heartwood-destroying fungi. 
- Qut of the total number of trees open to inoculation through knots 
on the optimum area only 18.2 per cent became infected in this way, 
on the intermediate area only 11.4 per cent, and for all combined 
just 15 per cent. In other words, in the trees studied the chances 
_ for a tree becoming infected with dry-rot through branch stubs were 
merely 15 out of 100. 


46 BULLETIN 871, U. S. DEPARTMENT OF AGRICULTURE. 


An examination of knots on the outside of a log or tree usually 
does not give any reliable indication of the condition of the heart- 
wood with respect to its degree of soundness. In this respect dry- 
rot differs markedly from the stringy brown-rot (Echinodontium 
tinctorvum) in white fir and the ring scale or red-rot (Z’rametes pini) 
in Douglas fir. th: 

Fire and knots are responsible for over 90 per cent of the infections 
and severe cull cases; other factors are of minor importance. 

About 3 per cent of the infections on the combined areas entered 
through wounds the causes of which it was impossible to exactly 
determine. Some of these may have been fire wounds, others 
lightning. Of all such wounds 23 per cent subsequently became 
infected. 

Lightning is of little importance as a means of entrance for dry-rot. 
On the intermediate area only 2.5 per cent of the infections are 
traced to this source, on the optimum area 1.5 per cent, and for the 
combined areas 2 per cent. Asa rule, lightning causes small super- 
ficial scars offering little opportunity for inoculation, but at times 
large areas of the cambium and bark are killed. This dead bark 
then drops off, exposing the sapwood, which dries out. Cracks 
opening up into the heartwood are formed, and such large areas 
offer a good chance for the lodgment of fungous spores. This con- 
dition is reflected in the percentage of risk of inoculation when it is 
found that 19.2 per cent of the lightning-struck trees on the optimum 
area, 31.8 per cent on the intermediate area, and 25 per cent for the 
combined areas were infected by dry-rot through lightning wounds. 
This figure is higher than that for all other factors except fire. The 
chief reason, then, that lightning wounds are of so little importance 


in relation to decay is not that the character of wounding on the 


whole is such as to offer little opportunity for inoculation, but rather 
that this type of wounding is rare. 

As an actual means of entrance of decay, frost cracks are even less 
important than lightning wounds. These cracks, while often of 
considerable length, even then present only a very narrow opening 
exposed to the air, the chances of fungous spores lodging in such a 
small opening being exceedingly small. Not quite 1 per cent of the 
infections for the combined areas entered through frost cracks, 
while the risk of infection is only 10.4 per cent lower than for all 
others except broken and dead tops. But though a rare source of 
infection, frost cracks sometimes carry an infection, entering through 
some other type of wound, over a greater linear extent in the heart- 


wood than might normally be expected, thus resulting in a large 


proportion of cull. The pockets of dry-ret do not occur in the wood 
immediately adjacent to the cleft or crack, but are usually found 
some distance removed, leaving the wood around the crack sound. 


DRY-ROT OF INCENSE CEDAR. 47 


This is because of the avoidance by the fungus mycelium of the wood 
around open fire scars. 

Infections through broken or dead tops may be absolutely disre- 
garded, both numerically and in respect to the resulting decay. 
Out of the 75 trees with these injuries only one infection occurred, 
and this resulted in a negligible amount of decay. 

However, the true relation of these various types of mechanical 
injuries to one another in respect to their importance as a means for 
the entrance and development of dry-rot on the areas studied is not 
expressed by the percentage of the total infections for which each 
type of injury is responsible, but must be shown by the relation of 
the number of trees infected through each type of wound to the 
total number of trees both sound and infected. The figures in 

‘Table XI express this relation, which might be termed ‘‘ percentage 
of risk of infection.”” In one set of figures is expressed, then, for the 
trees actually studied the numerical relation of the various types of 
injuries combined with the relative chances for inoculation offered 
by each. All the areas are combined. 


TaBLE XI.—Risk of infection of incense-cedar trees with dry-rot entering through wounds 
of the various types. 


_Risk of _Risk of 
Cause of wounding. mann Cause of wounding. ge 
cent). cent). 
USE ELAS 5 ube) Se AOSOM) | LAGIGMIN Gt: seca cca so dae cacti cee cece cee 1.2 
ATT TG ee ewes LSS Sa LOS Gn ate eek nao ee alteees owacenee 5 
(OU NCo) a0 ee er 1.6 || Broken or dead tops..:..........---..-- ok 


The figure 40 for fire expresses the fact that of all the trees analyzed 
each tree had 40 chances out of 100 of being wounded by fire and 
subsequently becoming infected with dry-rot through this wound, 
and so on for the other types of injury. 

The far greater importance of fire wounds as a means of entrance 
for dry-rot as compared with all other injuries is strikingly brought 
out. Knots, the nearest competitor, are far less important, while 
all the others practically can be neglected. 

The close relation of wounds and infections is shown even better 
in figure 3. The curve for wounds is plotted from Table IX, knots, 
of course, not being included, for had this been done the wound 
curve would have followed the 100 per cent ordinate throughout all 
the ages. The curves for infections and cull are the same as those 
given in figure 2. ; 

These curves show that infections are practically a function of 
- wounds, the two curves having almost the same form, but of course 
_ the infection curve being lower throughout until both have attained 
100 per cent. The curve for the percentage of cull is included in 


48 BULLETIN 871, U. S. DEPARTMENT OF AGRICULTURE. 


order to emphasize the fact that while the increase in the number of 
wounds is closely followed by an increase in infections, the increase 
in the amount of cull due to decay is not a direct function of the 
increase in infections, but is also dependent upon the factor of age 
and thrift, as previously explained. 

Meinecke (16, pp. 47-48) found in white fir that a combination of — 
suppression and severe wounding was a prerequisite for serious 
decay in trees up to the age of 150 years. This does not hold for 
incense cedar. Of the ten severe cull cases in suppressed trees up ~ 
to the age of 165 years, five occurred in trees slightly wounded, one ~ 
in an entirely unwounded individual, and only four on severely~ — 
wounded trees. Of the four dominant trees below the same age — 
with severe cull cases, two are severely wounded and two slightly — 


80 fy vap above ce 


ico 


| Percent 


80.200 20 40 60 80 300 20 40 60 400 
Age - Years 


ee? ee: 
hae eee) sh | 
RONG Se hes a 


Fic. 3.—Relation of the age of incense-cedar trees to wounds, infections, and cull. 


wounded. And, in fact, throughout all the age classes occur trees — 
slightly wounded but with severe cull cases. . 
The foregoing considerations lead to the following conclusions: — 
(1) Fire is responsible for by far the greatest number of dry-rot — 
infections, commonly leading to serious decay, resultmg in heavy 
cull. Fire is three times as important as its closest competitor, — 
knots. (2) Knots are responsible for some far-reaching decay, but 
most of the infections through knots are confined to the immediate 
vicinity of the knot. (3) Aside from fire and knots all other means — 
of entrance for decay are of little import. Lightning would be — 
serious except that wounding from this source is rare. Frost is of 
no importance in promoting inoculation, since the wounded surface 
presented is small and frost cracks are relatively few. However, — 
frost cracks often assist in carrying the dry-rot over a greater length 
of the bole than would be normal. Damage from unknown causes 
leads to some infection, but it is not of much importance. Infections 


DRY-ROT OF INCENSE CEDAR. 49 


through dead or broken tops are so insignificant that they may be 
entirely disregarded. (4) Severe wounding is not a prerequisite for 
severe cull cases or extensive decay at any stage in the life of incense 
cedar. 
APPLICATION OF RESULTS. 
RELATIVE IMPORTANCE OF DRY-ROT. : 


In the foregoing discussion the one big factor which stands out 
almost to the exclusion of all others is the dry-rot. Mechanical 
injuries of certain types play some rdéle, not only in destroying 
merchantable timber values but in lessening the annual increment. 
However, it is chiefly the fact that wounds are the means for the 
entrance of dry-rot which makes them of any but insignificant 
importance. 

Factors reducing the annual increment of the host, namely, Gym- 
nosporangium blasdaleanum, Phoradendron jumperinum libocedri, Stig- 
matea sequoiae, and Herpotrichia nigra are of minor importance. In 
fact, only the first two named, being decidedly ubiquitous, are 
worthy of the least consideration; but the resulting loss is so slight 
and intangible that under present conditions it may well be disre- 
garded except incidentally. The rare trifling loss in merchantable 
timber from burls of the mistletoe can not be of consequence. 

Fungi such as Polystictus abietinus, P. versicolor, Polyporus volva- 
tus, and others (see p. 4), only attacking dead wood and never 
found on living trees, are to be regarded as beneficial, since they 
hasten the decomposition of ground litter, thus increasing the humus 
in the soil and removing a serious fire menace. 

Loss resulting in the heartwood of living trees from the so-called 
secondary rots is very slight in the aggregate. It is rare that such 
decays are at all far-reaching, and, furthermore, it is possible that 
certain of them may be abnormal forms of the dry-rot. 

To repeat, then, the one big consideration from a pathological 
viewpoint which must hold above all in the silvicultural treatment 
and utilization of incense cedar is the dry-rot, together with the 
interrelated mechanical injuries. | 


CONTROL OF DRY-ROT. 


Very little can be hoped for in the line of any serious consideration 
or attempt at direct control of dry-rot on private holdings for years 
tocome. Tne private owner is averse to any increase in expenditures 
which does not show prospects of immediate gain. On certain private 
holdings where the incense cedar was heavily affected by dry-rot, all 
the trees have been left standing, only the more valuable species | 
being removed, leaving the diseased individuals to continue spreading 
the decay to uninfected members of the present and future genera- 
tions. 


\ 


50 BULLETIN 871, U. S. DEPARTMENT OF AGRICULTURE. a 


On the National Forests a great deal can be accomplished in the | 


way of control of mechanical injuries resulting in wounds through 
which the dry-rot fungus can enter. As has been shown, fire is by 


far the most important factor in promoting dry-rot, with knots, the — 
nearest competitor, of relatively far less importance both in regard — 


to the number and seriousness of resulting infections. 

Fire can be, in a great measure, directly controlled. The ever- 
increasing efficiency of the fire-protection methods on the National 
Forests, with the continual reduction in the number of damaging 
fires, speaks for itself. Certain private holdings are also protected 
from fire, either incidentally by falling within the boundaries of a 
National Forest or through a protection system handled on a coop- 
erative basis by the United States Forest Service. Knots, of course, 
can not be controlled. Natural pruning, with the continual produc- 
tion of dead branches, which later break off, is inevitable in any 
forest. However, it may be expected that infections through this 
source will become increasingly fewer as time goes on, in proportion 
to the reduction in the number of fire-wounded trees. All other 
factors, whether controllable or uncontrollable, and this includes frost 
and lightning, are of so little importance that they may be neglected 
in any consideration of mechanical injuries in the future stand. ) 

But fire protection works for the future welfare of the stand alone. 
It can not affect the huge number of individuals in the forest with 
healed or open wounds through which dry-rot has already entered 
or those uninfected individuals with open wounds still exposing them 
to attack by heartwood-destroying fungi; nor can it have any influ- 
ence on all the other injured, diseased, or distorted members of the for- 
est community. These have no place in the stand, are in most cases a 
direct menace to the sound trees, and should be removed as soon as 
possible. Unfortunately, we have not been able to attain the highly 
desirable intensive practice of eradicating such undesirable individuals 
by means of improvement thinnings applied at will wherever needed 
in the forest. 

Under present conditions this can only be done in the main through 
timber sales, with free-use permits playing a limited part. But the 
Government is far from able to sell the timber where cutting is most 
needed from a silvicultural point of view. Economic factors, espe- 
cially transportation, and in some cases the degree of soundness of 
the stand play the chief réle in determining. the exact location of a 
sale area. In fact, a mature or overmature stand badly in need of 
cutting may have to be left untouched, owing to the refusal of pros- 
pective purchasers to handle the high representation of inferior 
species. 

In the case of incense cedar, this prejudice on the part of the lum- 
berman does not arise from any inherent qualities or characteristics 


7) es 


ee eee Re) ee ee a 


Min S Sane, <i 7 


DRY-ROT OF INCENSE CEDAR. 51 


of the timber itself, but from the heavy infection of dry-rot in the 
mature and overmature trees, with the resulting high percentage of 
cull. Sound incense cedar is distinctly of high value and much 
sought after for special purposes, such as pencil slats, and in a lesser 
degree for cabinet material and interior finish. Wood not too badly 
decayed is of some value for posts and low-grade railroad ties. But 
the lumberman is naturally averse to handling a large quantity of 
unmerchantable material in order to secure a small percentage of a 
really valuable product. 

The first step in overcoming this objection must be the application 
of a careful scaling policy. 

d ; SCALING. 


In order to handle incense cedar properly on a timber sale the 
outward indications of hidden defect should be thoroughly under- 
stood. A valuable index to the condition of the timber will be 
found in the presence of sporophores or shot-hole cups on the trees. 
When found, their apparent age should be carefully taken into 
account in determining the degree and extent of the dry-rot (see 
p. 10). Excellent clues as to how a decayed tree should best be 
bucked are contained in the occurrence of shot-hole cups or sporo- 
_ phores. Since heavy dry-rot almost invariably extends from the 

_ground level to a varying height above the highest sporophore or 
shot-hole cup it would, of course, be a waste of labor to buck the 
tree again at any place between the stump height and the last- 
named point. 

The scaler should keep in mind the relation of wounds, particu- 
larly those caused by fire, to dry-rot in the tree. A large pocket of 
dry-rot occurring close to a healed wound, especially fire scars in 
the butt of the tree, usually diminishes in area as the height increases 
and ends in a point immediately above the termination of the healed 
fire scar it is following. For example, in case a butt log shows a 
large pocket of decay adjacent to a healed fire scar on its basal 
cross section, while the top cross section is absolutely sound, it is 
safe to assume that the decay will end about 6 feet from the base 
of the log, or in exceptional cases a length of 10 feet may be attained 
(see p. 44). 

Particular care should be used in scaling butt logs with an open 
fire scar at the base. As has been shown (see p. 44), dry-rot of any 
seriousness is rarely found in the dried-out wood around an open fire 
scar. The base of such a log is nearly always absolutely sound; 
the top may show the entire heartwood unmerchantable. It is 
quite possible, then, for the scaler to judge the decay as extending 
half way down the log from the top, giving the lower half full scale 
and judging the upper half unmerchantable. This procedure is 


52 BULLETIN 871, U. S. DEPARTMENT OF AGRICULTURE. 
particularly likely to be followed. on double-length logs (20, 24, 28° 
feet, etc.). But invariably the dry-rot will commence just at the 
top of the fire scar and almost immediately spreads out over the 
entire radius of the heartwood. In other words, in a log with an 
open fire scar showing on the base but otherwise sound and with — 
pockets of dry-rot in the top end, the decay should be considered as — 
beginning at about the top of the fire scar and extending from there 
to the upper end of the log in practically the same degree and radial 
extent with relation to the heartwood as is shown on the top end. 

Advance rot (see p. 13) should be treated just the same as mature © 
dry-rot. 

In the case of a large swelling on the bole caused by mistletoe it 
is best to have the tree bucked in such a manner as to exclude the © 
swelling rather than have such a defect reach the landing as part — 
of an otherwise sound log and then be scaled out. 


q 


MARKING. 


Timber sales at present offer the only extensive means of prac- © 
ticing intensive silviculture on our National Forests, and the entire 
results are absolutely based on correct marking. Fundamentally, 
the object of marking is to leave the stand in the optimum condition — 
for its future welfare and development. This goal should never be — 
lost sight of, no matter how clouded the issue may be by a com- © 
plexity of immediate and often pressing considerations. To attain 
this end requires a high degree of skill, grounded on a thorough 
understanding of all the factors involved, not the least of which are — 
those making for total loss in the species under consideration. 

The fundamental object of marking has been far from completely 
attained if, after cutting, diseased individuals are left standing to — 
carry infection to otherwise sound trees of merchantable size, besides — 
menacing the future of the advance growth and reproduction. © 
Obviously, then, trees with sporophores or shot-hole cups should — 
invariably be marked for cutting, for these are positive proofs of 
damaging dry-rot. Such trees are as a rule not oniy a total loss, — 
being unmerchantable from the butt to varying distances of 10 to 
50 feet above the highest sporophore or shot-hole cup, but are the — 
most potent factors in spreading infection to other trees, since infec- — 
tion can only be brought about by spores coming from sporophores ~ 
on diseased trees. True enough, shot-hole cups in themselves do 
not menace surrounding trees with possible infection, but they do 
indicate that the fungus has reached fruiting maturity and is very — 
likely to develop more sporophores, as is attested by the not un- — 
common occurrence of two or more shot-hole cups of varying ages © 
on the same tree. Furthermore, the fungus mycelium in any in- 


DRY-ROT OF INCENSE CEDAR. 53 


fected tree possesses the potential capacity of sooner or later pro- 
ducing sporophores. 

Remembering the great percentage of dry-rot infections entéfing 
through wounds, trees with injuries must be treated accordingly. 
Trees with healed wounds are of less concern than those with open 
wounds, since the former, if not already infected, are immune except 
for the inevitable, though fortunately not frequent, attack through 
branch stubs, while the latte: are still open to infection. Then, too, 
the area of heartwood exposed by the injury is of grave consequence; 
the larger the area the greater the opportunity for infection. We 
already know the high percentage of infections through fire scars 
which so commonly expose large areas of heartwood; therefore 
fire-scarred trees, above all, should be marked as heavily as possible. 
Large lightning wounds are a serious danger, but small superficial 
injuries, especially if high up on the bole, can be almost disregarded. 
Frost cracks, though by virtue of the exceedingly small amount of 
heartwood they expose offering slight chance for infection, often 
aid in spreading infection established through some other agency, 
and trees with such wounds should be marked for cutting whenever 
possible. From the pathological viewpoint spiketops or stagheads 
may be almost disregarded except for their suppressing influence 
on the injured individual, but sound silviculture demands the re- 
moval of such trees from the stand. 

Hven if the Utopian dream of a forest community without injured 
individuals could be attained, this in itself would not result in com- 
pletely controlling the ieckaadtion wrought by the dry-rot fungus, but 
only in minimizing it in a great measure. There would still be some 
loss from infections entering through knots. Then, too, no matter to 
what degree of intensive management a forest in this region may be 
brought in the future, some injuries will always occur, even from fire, 
while frost and lightning wounds are inevitable. The unavoidable 
injuries to a certain number of the seed trees during logging on any 
gales area must not be overlooked. 

Therefore, all wounded trees must not only be eliminated on sales 
areas, but trees, even though unwounded and thrifty, must not be 
left with the expectation that they will be sound at the next cutting 
if by the time the cutting takes place they will have attained or 
passed beyond the age at which loss from dry-rot becomes of serious 
economic importance. It has been shown that the critical age occurs 
at 165 years and the age of decline at 210 years. Beyond the age of 
165 years suppressed trees become subject to extensive decay, while 
up to that age they may be expected, with rare exceptions, to remain 
relatively sound, the same being true for the dominant trees at an 
age of 210 years. 


54 BULLETIN 871, U. 8S. DEPARTMENT OF AGRICULTURE. 


Since in the intermediate range all but an insignificant percentage _ 
of the trees are suppressed in a greater or less degree, it becomes — 
obvious that in this region incense cedar should be cut by the time — 
it reaches 165 years, the critical age. 

In the optimum range, suppressed trees must not be allowed to 
pass 165 years and dominant individuals 210 years (the age of decline) 
before felling. 

Even in the distant future, when the risk of wounding in the j 
forests is reduced to a minimum, it is highly problematical whether 
a new age of decline can be established at a higher age, on account of — 
the entrance of decay through knots. Damaging dry-rot has entered — 
trees through knots beginning at 105 years, and while such cases are 
rare in the years below the critical age and age of decline, yet they 
are sufficient to indicate that this condition will always have to be 
reckoned with. Furthermore, as time goes on, the increasing value 
of timber will result in noticeably lowering figures as to what con-_ 
stitutes an allowable percentage of cull in any species. 

From a pathological viewpoint the critical age must limit the robes 
tion of incense cedar in the intermediate range. It is doubtful — 
whether even in the managed stands of the future the incense cedars — 
in this range will be other than suppressed in most cases, since the. 
present widespread suppression does not seem to be the result of any 
influence that could be removed by a system of forest management, 
arising apparently from the fact that the cedar is removed from the 
region of its optimum development. 

In the optimum range the rotation must be limited by the age of 
decline. The critical age is not so important except during the period 
of transition, for suppressed trees, while common enough in the virgin | 
stands of to-day in this range, will have little place in the managed © 
stands of the future. Here, the species being in its optimum, nothing 
but thrifty, dominant individuals should be produced under a rational 
system of management. 

The influence of decay on harvesting a timber crop was hinted at 
years ago by Von Schrenk (27, p. 203) and clearly pointed out by 
Meinecke (16, p. 61) for white fir. Mitchell (17, p. 32) took this 
so-called pathological rotation carefully into account, recommending ~ 
a rotation of 150 years, at which time the species attains a good © 
merchantable size. The rotation recommended by Mitchell is based — 
on Meinecke’s preliminary study of dry-rot. : 

As a result of the present study, the pathological rotation for 
incense cedar must be placed at 165 years in the intermediate and — 
210 years in the optimum range. During the transition period, while — 
suppressed trees are still a factor in the optimum range, these should — 
be cut when not older than 165 years. This does not mean that in 
the two regions under consideration cedar can best be cut at regular — 


i 


DRY-ROT OF INCENSE CEDAR. 55 


intervals of 165 and 210 years, respectively, but simply that if it is 
left to a greater age there is a full realization of the resulting enor- 
mously increased loss through dry-rot. The pathological rotation 
becomes a maximum limiting factor for the actual rotation, which 
may be financial, silvicultural, or one of maximum volume, depending 
on conditions in the future. From present indications it is highly 
probable that all other rotations for incense cedar will fall below the 
pathological rotation in both regions; the difference will be quite 
marked in the optimum range. It is possible in the optimum range 
that during the transition period, if necessary to leave suppressed 
trees standing after cutting, the increased vigor of such individuals 
_ which may follow the opening up of the stand might raise the critical 
- age somewhat, but in the present state of our knowledge not only 
regarding the influence of thinning on the development of wood- 
destroying fungi in standing trees, but in the case of incense cedar 
_ regarding the actual response of the trees themselves, this consider- 
ation is entirely too hypothetical to influence our present conclusions. 


at ~ SUMMARY. 


The results of this study point to the following main conclusions: 

(1) Incense cedar is classed as an inferior species because of a 
uniformly heavy percentage of cull caused by the dry-rot fungus 
(Polyporus amarus). Judicious scaling and instruction in the proper 
methods of bucking will ultimately aid materially in changing this 
View. 

(2) Dry-rot can be eliminated in a large measure from future stands 
by intensive fire protection, but it can not be entirely controlled in 
this way, owing to the continued occurrence of unavoidable mechan- 
ical injuries caused by pruning, lightning, and frost. 

(3) The following directions should apply to marking on timber 
sales: 


(a) Trees with sporophores and shot-hole cups must be marked for cutting. 

(6) Seriously wounded trees, especially those with fire scars, should be marked to 
be cut. 

(c) In the intermediate range all but a very small percentage of the trees are sup- 
pressed. Since suppressed trees are subject to severe dry-rot after they pass the 
critical age of 165 years, trees left standing should be of such an age that they will not 
_ pass that age before the next cutting occurs. Dominant trees, being so few, may be 
classed with suppressed trees, but in reserving seed trees only the most thrifty indi- 
viduals should be considered. By this practice some dominants will be among the 
trees left, and these will be safe until the age of 210 years is reached. 

(d) In the optimum range, suppressed trees are subject to damaging dry-rot after they 
pass the age of 165 years (the critical age), while dominant trees are safe until 210 years 
_ (the age of decline) is reached. Therefore, suppressed trees left standing must be of 
_ such an age that they will not pass the critical age (165 years) before the next cutting 
occurs, and dominant trees left should not pass the age of decline (210 years) before the 
next cutting. Suppressed trees, however, should be heavily marked for cutting and 
only left unmarked if unavoidable. | 


56 BULLETIN 871, U. S. DEPARTMENT OF AGRICULTURE. 


(4) The rotation for incense cedar must not exceed 165 years in 
the intermediate and 210 years in the optimum range. 

If for any reason the pathological rotations, as determined in this 
paper, must be exceeded in future operations on cut-over lands, 
the forester in making the decision will have a full realization of the 
gadziuens Joss. in, manekantablasianadlc ta aeee through cumulative 
risk of cull due to dry-rot in the stands so handled. | 


DRY-ROT OF INCENSE CEDAR. 57 


LITERATURE CITED. 


(1) Bryant, R. C. 
1913. Logging . . . ed. 1, 590 p., 182 fig. New York, London. 
(2) CHapman, H. H. 
1913. Coérdination of growth studies, reconnaissance, and regulation of 
yield on national forests. In Proc. Soc. Amer. Foresters, v. 8, no. 3, 
p. 317-326. 
(3) Cooxs, M. C., and Harkness, W. H. 
1881. Californian fungi. Jn Grevillea, v. 9, no. 51, p. 81-87, 1881. (Con- 
tinued article. ) 
(4) Exuis, J. B., and Evernart, B. M. 
1892. The North American Pyrenomycetes ... 793 p., 41 pl. Newrfield, 
N. J. 
(5) Fartow, W. G., and Srymour, A. B. 
1888-91. Provisional host-index of the fungi of the United States. 3 v. in 1. 
Cambridge. 
(6) GREELEY, W. B. , . 
1907. A rough system of management for forest lands in the western Sierras. 
In Proc. Soc. Amer. Foresters, v. 2 no. 1, p. 103-114. 
(7) Harkness, H. W. 
1879. A foe to the lumberman. Jn Pacific Rural Press, v. 17, no. 4, p. 49, 


1 fig. 
Hartic, RoBERT. 
(8) 1874. Wichtige Krankheiten der Waldbiume .. . 127 p.,6 pl. Berlin. 
(9) 1878. Zersetsungserscheinungen des Holzes der Nadelholzbaume und der 
Eiche in forstlicher, botanische und chemischer Richtung... 151 


p., 21 pl. (5 col.). Berlin. 
(10) Hepecock, G. G. 
1910. A new polypore on incense cedar. Jn Mycologia, v. 2, no. 3, p. 
155-156. 
(11) Jackson, H. S. 
1914. A new pomaceous rust of economic importance, Gymnosporangium 
blasdaleanum. Jn Phytopathology, v. 4, no. 4, p. 261-270, 1 fig., 
pl. 12-13. Bibliography, p. 268-269. 
(12) Lone, W. H. 
1914. Preliminary note on the cause of ‘‘pecky” cypress. (Abstract.) In 
Phytopathology, v. 4, no. 1, p. 39. 
(13) Mayr, HEInRIcuH. 


1909. Waldbau auf naturgesetzlicher Grundlage. . . 568 p., 27 fig., 3 pl. 
MEINECKE, E. P 
(14) 1912. Parasitism of Phoradendron juniperinum libocedri Engelm. In Proc. 
Soc. Amer. Foresters, v. 7, no. 1, p. 35-41, 2 pl. 
(15) 1914. Forest tree diseases common in California and Nevada... A manual 


for field use. 67 p., 24 pl. Washington, D.C. Published by the 
U.S. Dept. Agr. Forest Serv. 
(16) 1916. Forest pathology in forest regulation. U.S. Dept. Agr. Bul. 275, 62 p. 
— (17) Mrrcwett, J. A. 
1918. Incense cedar. U.S. Dept. Agr. Bul. 604, 40 p., 3 fig., 5 pl., 1 fold. 
map: ~<. 


58 BULLETIN 871, U. S. DEPARTMENT OF AGRICULTURE. 


(18) M6utER, A. | 
1904. Uber die Notwendigkeit und Méglichkeit wirksamer Bekampfung det 
Kiefernbaumschwammes Trametes Pini (Thore) Fries. Jn Ztschr. 
Forst u. Jagdw., Jahrg. 36, Heft 11, p. 677-715, pl. 4-5. 
Miuncu, Ernst. 
(19) 1907-8. Die Blaufaiule des Nadelholzes. Jn Naturw. Ztschr. Land u, 
Forstw., Jahrg. 5, Heft 11, p. 531-573, fig. 1-28, 1907; Jahrg. 6, 
Heft 1, p. 32-47, fig. 29-31; Heft 6, p. 297-323, 1908. 
(20) 1909. Untersuchungen iiber Immunitaét und Krankheitsempfainglichkeit der 
Holzpflanzen. Jn Naturw. Ztschr. Forst u. Landw., Jahrg. 7, 
Heft 1, p. 54-75, fig. 1; Heft 2, p. 87-114, fig. 2-5; Heft 3, p. 129-160. 
(21) 1910. Uber Krankhafte Kernbildung. Jn Naturw. Ztschr. Forst u. Landw., 
Jahrg. 8, Heft 11, p. 533-547, illus.; Heft 12, p. 553-569, 2 fig. 
(22) 1910. Versuche itiber Baumkrankheiten. Jn Naturw. Ztschr. Forst u. 
Landw., Jahrg. 8, Heft 8, p. 389-408, 3 pl.; Heft 9, p. 425-447, fig. 18. 
(23) 1915. Untersuchungen iiber Eichenkrankheiten. Jn Naturw. Ztschr. Forst 
u. Landw., Jahrg. 13, Heft ee p. 509-522, 6 fig. 
(24) Murritu, W. A. 
1915. Western Polypores. 36 p. 
(25) PuumMeEr, F. G. 
1912. Lightning in relation to forest fires. U.S. Dept. Agr. Forest Serv. Bul. 
111, 39 p., 16 fig. 
ScHRENK, HERMANN VON. 7 
(26) 1900. A disease of Taxodium known as peckiness, also a similar disease of 
Libocedrus decurrens. Jn Mo. Bot. Gard. 11th Ann. Rpt., p. 23-77, 
6 pl. (partly col.). 
(27) 1901. Fungous diseases of forest trees. Jn U. S. Dept. Agr. Yearbook, 1900, — 
p. 199-210, pl. 21-25. . 
(28) 1902. Notes on diseases of western conifers. Jn Science, n. s., v. 16, no. 
395, p. 138. — 
(29) 1903. The brown-rot disease of the redwood. Jn U. S. Dept. Agr., Bur. 
Forestry Bul. 38, p. 29-31. | 
(30) Supwortu, G. B. 
1908. Forest trees of the Pacific slope. 441 p., illus., 15 fold. pl.; want 
Published by the U. S. Dept. Agr. Forest Serv. | 
WEIR, J. R. 
(31) 1915. Some observations on abortive sporophores of wood- destroying fungi. 
In Phytopathology, v. 5, no. 1, p. 48-50. 
—— and Husert, E. E. 
(32) 1918. A study of heart-rot in western hemlock. U.S. Dept. Agr. Bul. 722, 
39 p., 13 fig. 
(33) 1919. A study of the rots of western white pine. U. 8S. Dept. Agr. Bul. 
799, 24 pp. 


ADDITIONAL COPIES 


OF THIS PUBLICATION MAY BE PROCURED FROM 
THE SUPERINTENDENT OF DOCUMENTS 
GOVERNMENT PRINTING OFFICE 
WASHINGTON, D. C. 

AT 


15 CENTS PER COPY 


, 
- 
rat 
io 4 
or 


UNITED STATES DEPARTMENT OF AGRICULTURE 


BULLETIN No. 934 


Contribution from the Bureau of Plant Industry 
WM. A. TAYLOR, Chief 


Washington, D. C. PROFESSIONAL PAPER June 16, 1921 


-~DAMPING-OFF IN FOREST NURSERIES. 


By Cari Hartiry, formerly Pathologist, Office of Investigations in Forest 


Pathology. 
CONTENTS. 
Page. Page. 
Damping-off in general____________ 1 Damping-off fungi as causes of root- 
Damping-oll of conifers.—_..4.___~ it rot and late damping-off_-______ 70 
a ee ee 27 | Relation of environmental factors to 
eaten yarum 1. __..____ 3 Gaim IN Ofte ses ee EV 75 
INS aS of 7 Density of some. fe a 74 
Pythium debaryanum_______-~_-_ oo. | Moisture and temperature factors__ 75 
*Rheosporangium aphanider- | | Chemical factors = 2 he = 79 
Cub Sh 2s Cpa auntie Tee homnse: See 82 
7 eerepntuora spp-— = —-—___.___ 59 | Acknowledgments____ ar 86 
Miscellaneous phycomycetes____. GTP | es Tete Veet ie tice a et 86 
(5 BA ig ge) a CF teravare: cited or oe et ot 91 
Relative importance of the damping- 
Ofetuner on conifers... ._____ 65 


DAMPING-OFF IN GENERAL. 


Damping-off is the commonest English name for a symptomatic 
eroup of diseases affecting great numbers of plant species of widely 
separated phylogenetic groups. It is commonly used for any disease 
which results in the rapid decay of young succulent seedlings or soft 
cuttings. Young shoots from underground rootstocks may also be 
damped-off before they break through the soil (66). The same term 
is even used for diseases affecting the prothallia of vascular crypto- 
gams (2). The name apparently originated in the fact that the dis- 
ease is usually most prevalent under excessively moist conditions. 
In those cases in which the disease becomes serious without the pres- 
ence of unusual amounts of moisture the term is a misnomer. It is, 
however, so thoroughly established in practical use that it would be 
impossible, even if desirable, to establish any other name. 


1 The serial numbers in parentheses refer to ‘“ Literature cited,” at the end of this 
bulletin. : 


-19651°—Bull. 9834—21—_1 


2 BULLETIN 934, U. S. DEPARTMENT OF AGRICULTURE. 


While the parasites reported as causing damping-off are probably 
not as numerous as the host species which are subject to it, a con- 
siderable number are known. Two quite different types of damping- 
off parasites may be recognized. In the first type we have fungi, — 
such as Pythiwm debaryanum Hesse and Corticium vagum B. and C., 
soil inhabiting and primarily saprophytic, which attack a great 
variety of hosts, and are at least better known, if not more destruc- 
tive, as damping-off organisms than as parasites on older plants. 
They are specialized as to the type and age of tissues which they at- 
tack rather than as to host. The second type includes fungi less 
common as saprophytes and with a relatively limited, sometimes very 
closely limited, host range. Phoma betae, the systemic parasite of — 
sugar beet (37), is an excellent example of the host-specialized para- 
site, transmitted in the seed and capable of seriously injuring various 
parts of the older plant at different stages of growth as well as at- 
tacking seedlings. 

Most damping-off parasites are sntempiedinee in habit between the 
extremes of these two types. Of those which are somewhat host 
specialized, the following may be mentioned: 


Phomopsis verans, the cause of foot-rot of eggplant, reported by Sherbakoff 
(128) as a frequent cause of damping-off of this host and believed to be 
carried on seed. 

Gibberella saubinetit (Mont.) Sace. (29) we the imperfect fungi which kill 
grain seedlings as well as cause diseases of the older plants (80; 126, 
p. 218). Species of Gloeosporium and Volutella named by Atkinson (2, 
p. 269; 52) as able to kill seedlings or cuttings of particular host plants. 

Glomerella (Colletotrichum) gossypii, described by Atkinson (1) and Barre 
(4) as likely to cause damping-off of cotton (112). 

Fusarium lini, the flax parasite, reported by Bolley (14) as destructive .to 
young seedlings. 

Phoma lingam, the cause of black-leg of cabbage, at least under inoculation 
conditions able to kill quickly seedlings of cabbage and other crucifers 
(72). 

Peronospora parasitica (Pers.) De Bary, a downy mildew attacking cabbage 
and various other crucifers, reported as killing thousands of very young 
cabbage plants in Florida seed beds (41). 

The entomophthoraceous Completoria complens, on fern prothallia (1; 87, 
p. 208). 

Bacillus malvacearum, a parasite of the leaves of cotton plants, which can 
also cause damping-off of its favorite host (113) and the bacteria from 
diseased cucumber plants with which Halsted (53) caused typical 
damping-off of cucumbers. ; 


Damping-off fungi with wider host ranges include Phytophthora 
fagi, Aphanomyces levis (100), Rheosporangium aphanidermatus 
(38, 39), Botrytis cinerea, and certain Fusaria. The so-called prop- 
agation fungus, “ vermehrungspilz,” a sterile damping-off mycelium 
which Sorauer (133, p. 321) believed related to Sclerotinia and for 
which Ruhland (115) has erected a new genus, considered by both 


s 


DAMPING-OFF IN FOREST NURSERIES. 5) 


authors the most serious enemy encountered in growing softwood 
cuttings in Germany, if distinct would be a further addition to these 
generalized parasites. However, it is now believed (34) to be identi- 
cal with Cortictum vagum. Common generalized parasites of older 
plants, such as Sclerotinia libertiana, Sclerotium rolfsi (129), and 
Thielavia basicola (47), capable of attacking roots or other parts of 
older plants of numerous species, may also be considered among the 
damping-off fungi when they cause the death of small seedlings,.as 
occurs, for example, in attacks by Sclerotinia libertiana on lettuce 
(20, p. 28) and celery (103, p. 536) in seed beds. Further study will 
probably result in multiplying almost indefinitely the number of 
more or less important damping-off parasites, both of the specialized 
and unspecialized groups, although the most important of the latter 
type are probably already known. 

Most of the references in literature to damping-off describe its 
occurrence in truck crops and the losses caused in these crops. Ac- 
cording to Halsted (53, p. 342), weed seedlings are also very com- 
monly attacked. Duggar (33) names lettuce, celery, cotton, sugar 
beet, cress, cucumber, and sunflower as especially susceptible to 
injury by the two most important damping-off organisms. Except 
for the plant species in which damping-off by seed-carried parasites 
is common, it appears that the economic damage from damping-off 
is serious only with plants whose culture involves the raising of the 
seedlings in crowded seed beds for subsequent transplanting. For 
example, tomatoes do not ordinarily suffer from damping-off in the 
field (70), but the growing of seedlings in flats for subsequent trans- 
planting is sometimes seriously hampered as a result of the preva- 
lence of damping-off. This same principle holds in general for trees. 
Broad-leaved trees, which are usually not as crowded in the seedling 
stage as are the conifers, seldom give rise to complaint on the score 
of damping-off. The conifers, subject to serious losses in nursery 
beds, are not believed to be greatly affected in this country by the 
better known types of damping-off under forest conditions (68) 
except in the less common cases in which seedlings come up in close 
groups from squirrel hoards, artificial seed spots, or similar sources. 

A considerable number of broad-leaved trees have been reported at 
one time or another as injured by damping-off, though complaints 
of commercially serious losses are not common. The cases which 
_ have come to the writer’s attention are listed below: 


Cause not determined: 

Orange (48, 108). 

Olive, in greenhouse at the University of California. 

Russian wild olive (Hlaeagnus sp.), serious at an Iowa nursery; oral re- 
port by Mr. C. R. Bechtle, formerly of the United States Forest Service ; 
at another nursery in the same region this plant was reported as very 
little subject to injury. 


4 BULLETIN 934, U. S. DEPARTMENT OF AGRICULTURE, 


Cause not determined—Continued. " 
Magnolia (31), troublesome if the pulp is not washed off the seed before 
planting. 
Eucalyptus spp. (88, p. 45; 131), serious under moist conditions. : 
Betula spp. Communication by Dr. Perley Spaulding, of the Bureau of 
Plant Industry ; found especially susceptible in a Pennsylvania nursery. 
Carob, at United States Plant Introduction Garden, Chico, Calit. Dr. 
Mel T. Cook states that damping-off is more serious in carob seedlings 
if the seed is removed from the pod than if pods and seeds are sown 
together. 
Robinia pseudacacia (18). 
Apple, in greenhouse at the Michigan Agricultural College. 
Sclerotinia sp. (Europe) : 
Betula (79), a disease of seed and germinating seedlings. 
Phytophthora fagi (Europe): 
Fagus. Hartig (59) and many other writers; seriously affected, even 
in forest. 
Platanus (15). 
Acer (15), A. platanoides and A. pseudoplatanus (86, 104). 
Robinia (59, 73). 
Fraxinus (73). 
Acacia (59). 
Cercospora acerina (Europe) : 
Acer platanoides and A. pseudoplatanus (58). 
Pythium debaryanum: 
Tilia europea and T. ulmifolia (137), serious. 
Robinia (75, p. 18-14), killing germinating seed. 
Catalpa (126). : 
Rhizoctonia: 
Citrus seed beds (130) ; much loss. 
Catalpa (126). ‘ 
Botrytis cinerea: | 
Catalpa (126). 

Fusariwm sp.: 

Citrus seed beds (130) ; much loss. 

The sugar beet is apparently the only plant whose damping-oft 
diseases have been investigated with any degree of completeness 
by modern methods. While there is a great mass of literature on 
damping-off, it is mainly descriptive and on control measures. Most 
of the reports of the causal relation between the different fungi and 
the disease in the various host plants have been based on demon- 
strations of the presence of the fungus in diseased seedlings. In 
a great number of these cases identification has been doubtful. 
Even when a fungus is known to belong to a parasitic species, it 
is by no means certain that the mycelium found belongs to a para- 
sitic strain. It has been found, for example, that only part of 
the strains of Corticitum vagum occurring in sugar beets are able 
to attack that host vigorously (38, p. 154). Similar data for pine 
appear in figures 1 and 2.. Furthermore, even parasitic strains of 
several of the damping-off organisms are so widely distributed as 


DAMPING-OFF IN FOREST NURSERIES. 5 


‘saprophytes that one of them might easily get into a killed seedling 
after some other parasite had caused its death. Not only in the 
case of seedlings killed by fungi like Peronospora parasitica, but in 


HOST PINOS BANKSIANA OES saq| PINUS RESINOSA 
YEAR| 1913 1914 1914 1917 | 19/8 
Eel Ea a a 2 


804. 
4/00 


$8 


ie) 


LWWING SEEDLINGS PER /001N CONTRO. 


Fig. 1.—Diagram showing the relative activity of different strains of Corticium vagum 
in inoculations made at the time of sowing the seed. In experiments Nos. 36, 45, and 
47 the values are plotted for the number of seedlings appearing above the soil. For the 
other experiments the number of seedlings surviving at the close of the experiment have 
been taken. Explanation of symbols: O=Strain 147, from spruce seedlings, Washington, 
D. C., 1910; +—strain 50, from pine seedlings, Nebraska, 1909; O=strain 233, from 
Elaeagnus sp., Kansas, 1913; —§=strain 230, from the same lesion as strain 233; 
@ =strain 183, from bean, New York, 1910. 


eens “PINUS BANKHSIANA Ree PINUS RESINOEA 
Bis Beare a 
A 


HOST 


YEAR 
EXPT, 


150 


SEEDLINGS SURVIVING PER 100/N CONTROLS 
6) 
ie) ie) 


Fig. 2.—Diagram showing the relative activity of different strains of Corticium vagum, 
as indicated by the number of seedlings surviving in inoculated soil. Explanation of 
symbols: @=—Strain 189, from sugar beet, Michigan, 1910 (light-brown mycelium with 
few sclerotia) ; A==strain 211 and A= strain 212, from sugar beet, Colorado, 1910; 
@=strain 186, from potato, Ohio, 1910; [=strain 187, from potato, New York, 1910; 
+ strain 205, from Douglas fir, Colorado, 1911;, X=strain 192 and O-=strain 206, 
from pine, Nebraska, 1911. 


cases of true damping-off produced by the rotting type of parasite, 
much of the rapid decay of the seedling after death is brought 
about by bacteria and fungi other than the one causing death. 


6 BULLETIN 934, U. S. DEPARTMENT OF AGRICULTURE. 


Inoculation experiments are therefore probably even more neces- | 
sary in damping-off investigations than in studies of most other dis- _ 


eases in order to demonstrate etiological relationships. Unfortu- | 


nately, most of the inoculation work with damping-off organisms 
prior to 1900 was either crudely done by placing. diseased seedlings 
against healthy ones or consisted of experiments in which purity 
of cultures and validity of controls did not receive sufficient con- 
sideratién. Recent investigations not primarily directed toward 
damping-off, but which have decidedly increased our knowledge of 
the relation between Corticium and the disease, are those of Peltier 
(98) and Fred (43). The latter established a strong presumption 
that the difficulty in securing stands of various field crops having 
oily seeds in soil where green manures had been recently turned 
under is due to the killing of the sprouting seed by damping-off 
organisms. ; 

In tobacco, sugar beet, and pine, whose damping-off has received 
considerable attention, it has been found that the damping-off proper 
is commonly preceded by the killing of many of the sprouting seeds 
in the soil (38; 68, p. 522; 81, p. 5) and followed, after the plants 
become too large to be killed by the damping-off organisms, by root 
sickness and the death of small roots (88, p. 161; 64; 100). This latter 
has been reported also as a serious matter in the case of Corticium 
vagum for potato (51), a host on which damping-off is not important 
because of the lack of commercial propagation from seed. Pythiwm 
debaryanum further has been reported as continuing to work in the 
‘cortical tissues and leaves of tobacco plants which have been in- 
fected too late to result in death (81). 

The fact that a number of the damping-off fungi are able to attack 
young or soft tissues of so great a variety of plants and are much 
less able to kill older plants suggests that resistance to damping-off 
may be in part based on purely mechanical factors. Hawkins and 
Harvey (71) recently have extended to Pythiwm debaryanum the 
idea, developed by Blackman and Welsford (12) and Brown (16) for 
Botrytis cinerea, of the importance of mechanical penetration in the 
fungous invasion of plant tissues. While for 4. cenerea mechanical 
pressure was found to be the main factor only in cuticle penetration, 
with P. debaryanum the penetration of the cell walls of all parts of 
the potato tuber was apparently largely dependent on mechanical 
puncturing by the hyphee, only tubers with mechanically weak cell 
walls being susceptible to decay by the fungus. The extreme sus- 
ceptibility to P. debaryanum and Corticium vagum of soft, thin- 
walled tissues and the resistance of older stems and root parts would 
fit in well with such a theory as to the method of wall penetration, 
as in the older tissues the thicker cell walls would obviously be a 
serious bar to the extension of a fungus dependent partly or en- 


- 


DAMPING-OFF IN FOREST NURSERIES. if 


tirely on mechanical puncturing for its progress from cell to cell. 
Hartig (61, p. 147-150) shows a fungus which he does not name, but 
which is evidently a species of Fusarium, ‘dissolving the young un- 
cuticularized epidermis of pine seedlings; but he states that it.can 
not so dissolve older epidermis. The increased protective value of 
the epidermis of older plants can only in part explain the immunity 
most of them develop against serious attack by damping-off organ- 
isms, as lesions already started or which may later develop from the 
infection of young roots are unable to extend into the older parts 
of the plants. 

It may be mentioned here that the writer in a very preliminary 
test found strains of Corticium vagum and Fusarium moniliforme 
Sheldon which had been proved able to’ cause damping-off of pines 
also apparently able to destroy filter paper in inorganic salt solu- 
tion, while Pythiwm debaryanum seemed not so able. Ruhland 
(116), on the other hand, found the strain of the “ vermehrungspilz ” 
(Corticium vagum) which he tested to be very weak in ‘cellulose- 
destroying ability as compared with Botrytis cinerea. 


DAMPING-OFF OF CONIFERS. 
HISTORICAL. 


While the losses from damping-off in seed beds of dicotyledonous 
tree species are occasionally serious and in the case of beech in 
Europe have required considerable study, they have been so far 
overshadowed in this country by the losses in coniferous seed beds 
that practically all the attention thus far, both as to etiology and 
measures of prevention, has been devoted to the disease in conifers. 

The literature on the damping-off of conifers is considerable. 
A large part of it, because of the extensive early development of 
plant pathology and forest .planting in Germany, has been writ- 
ten by Germans. A large portion of the German articles on it 
was either by foresters or by botanists in the day when most patho- 
logical work was of the reconnaissance type. Therefore, while the 
work of one of the best known of the parasites on coniferous seed- 
lings was noticed in Europe as early as the eighteenth century (21, 
_ p. 252-253) most of the European data available are observational. 
The only fungi which were at all definitely connected with the dis- 
ease on conifers seem to have been Fusarium (/usoma spp.) and 
Phytophthora fagi (P. omnivora De Bary in part). The damping- 
off Rhizoctonia was described in Germany in 1858 and Pythiwm de- 
baryanum in 1874; the fact that neither of these, important in conif- 
trous seed beds in both the eastern and western United States, has 
ever been reported from conifers in Europe is perhaps the best evi- 


a 


8 BULLETIN 934, U. S. DEPARTMENT OF AGRICULTURE. 


dence of the relatively small amount of actual investigation carried 
on there on this disease in the nurseries. A number of references to 
the damping-off of conifers in the English horticultural and botani- 
cal literature yield even less definite information as to the causal 
fungi than do the German articles. : 

With the awakening of interest in reforestation in the United 
States between 15 and 20 years ago and the first efforts to grow 
pines in quantity for forestry purposes, attempts were made to de- 
termine the cause of the disease in this country and to develop direct- 
control methods. Duggar and Stewart (32) made what appears to 
be the first report of Rhizoctonia in connection with the damping-oft 
of conifers. Spaulding (136, 137), in work begun in 1905, con- 
tributed much to our knowledge of the etiology of the damping-off 
of pine in this country, especially in relation to Fusarium, and origi- 
~nated the sulphuric-acid method of control. The writer in 1910 re- 
ported preliminary inoculations on conifers with both Rhizoctonia 
and Pythiwm debaryanum (62). The work of Gifford (46) and 
Hofmann (77) added to the information on the causal relation of 
Fusarium spp. and P. debaryanum, respectively. Hartley, Merrill, 
and Rhoads (68) have recently established the parasitism of a num- 
ber of strains of the Corticium vagum type of Rhizoctonia on pine ~ 
seedlings under inoculation conditions, have confirmed Spaulding’s 
conclusions as to the parasitism of Fusarium moniliforme Sheldon, 
and have given preliminary data on other fungi. They consider P. 
debaryanum and C. vagum more important in pine seed bedsthan any 
single Fusarium species. Hartley and Hahn (69) have announced 
successful inoculations on pines with P. debaryanum and Rheospo- 
rangium aphanidermatus Edson, with less satisfactory evidence of 
the parasitism of Phytophthora sp. and a fungus tentatively referred 
to Pythium artotrogus. Hartley and Pierce (67) report the finding 
of P. debaryanum in Tsuga mertensiana and Pseudotsuga taxifolia 
as well as in the pines. In damped-off pine seedlings they find P. 
debaryanum more commonly than C. vagum, especially in beds which 
have received disinfectant treatments. Other considerations, how- 
ever, keep them from concluding that the former is necessarily the 
more important of the two. Both of these latter papers and all of 
the reports of Pythium with the exception of Hofmann’s are brief 
notes, presenting no evidence in support of the statements made. 


DESCRIPTION. 


The symptoms of damping-off in conifers have already been de- 
scribed in some detail (68). In the paper cited, injury due to exces- 
sive heat of the surface soil and injury caused by high wind, both of 
which may easily be confused with damping-off, are described and 
accompanied by colored illustrations both of different types of damp- 


————————— eee 


DAMPING-OFF IN FOREST NURSERIES. 9 


ing-off and of these nonparasitic troubles. The detailed descriptions 
will not be repeated here. A brief summary of the different types 
of disease recognized as included in damping-off follows: 


(1) Germination loss: The radicles are killed very soon after the seeds 
sprout and before the seedlings can appear above ground. This is an important 
type, which can be caused probably by any of the organisms commonly capable 
of causing the better known types of trouble (61, 68, 68, 187). 

(2) Normal damping-off (figs. 3, 4, and 5): The seedlings are killed by fungi 
invading either the root or hypocotyl after the seedling has appeared above the 
soil and while the stem is still dependent largely on the turgor of its cortical tis- 
sues for support. In sandy soils root infection is more common than hypocotyl 
infection, though the latter is the type most emphasized in the early horticul- 
tural descriptions. Biittner (26) some time ago recognized the frequence of 


Fie. 3.—Normal type of damping-off of Pinus ponderosa. At the left is a damped-off 
seedling or root sprout of the southwestern ragweed (Ambrosia psilostachya). (Photo- 
graphed by S. C. Bruner.). 


root infections. Damping-off in beds out of doors is primarily in most cases a 
root rot, either of this type or of the types preceding and following. 

(3) Late damping-off includes cases of the root-rot type occurring only after 
the seedling stems have started to become woody and the cortex has begun to 
shrivel. The damping-off parasites, or at least part of them, continue to kill 
seedlings by rotting their roots for some time after the stems become too woody 
to be decayed. The seedlings affected do not fall over till a considerable time 
after death. For convenience, all cases of this sort up to the purely arbitrary 
age of two months are classed as damping-off. However, in weather permitting 
of average speed of development the seedlings are usually able to resist attack 
before they reach this age. Seedlings at the marginal age between suscepti- 
bility and nonsusceptibility to killing infections are found often with the 
younger parts of their roots killed, but with the older portions apparently able 
to resist invasion by the fungus, recovery taking place by laterals. Dr. 
R. D. Rands and the writer in 1911 established the ability of seedlings from 
43-day-old beds of Pinus sylvestris, P. banksiana, P. nigra austriaca, and P. 
nigra poiretiana to survive such infections, even when more than half of the 
root system has been destroyed, by transplanting such root-sick seedlings and 


10 BULLETIN 934, U. S. DEPARTMENT OF AGRICULTURE. 


observing their continued growth (fig. 6). An article recently found (25) shows 
that Biittner had earlier made the same sort of demonstration of recovery of 
root-sick conifers. Observations on olive seedlings in 1916 showed cases of 
partially rotted roots which were recovering by sending out lateral root 
branches. 

(4) Top damping: The cotyledons or upper part of the stem are invaded by 
the parasite, sometimes before the seedling breaks through the soil. The infec- 
tion may or may not be fatal. A special case of this type, probably caused by a 
different parasite from those most commonly active, is that which in a publica- 
tion above referred to was described and figured as “black-top (68). ees 


Fic. 4.—The beginning of an epidemic in drill-sown Pinus banksiana. Black crosses (X) 
indicate disease foci where the germinating seed were apparently killed and from which 
the disease is now spreading to adjacent seedlings. (Photographed by Dr. J. V. 
Hofmann. ) 


distinguished from ordinary top damping by the very dark color of the invaded 
tissues and its apparent dependence on some unusual set of climatic factors for 
its progress in the seedling after infection. 

The killing of dormant seed by fungi is a matter of some practical 
interest in seed beds, and possibly still more so in forests, as it may 
help to explain the failure of certain conifers to reproduce except on 
mineral or certain other special soil types (68). With sugar beets 
Pythium debaryanum (100) is said to attack dormant seed as well 
as seeds which have sprouted. It is to be presumed that with conifers 
some of the damping-off fungi will be found to attack dormant as 
well as sprouting seed. ‘This matter is now under investigation. 


we 


il ital 


“ 


DAMPING-OFF IN FOREST NURSERIES. 11 


Something is already known about the seed fungi of herbaceous 
plants (76, 91), broad-leaved trees (79, 92), and juniper (95). 


RELATIVE IMPORTANCE OF THE DIFFERENT TYPES. 


Of the types of damping-off described in the foregoing pages the 
first two are ordinarily the most important. Late damping-off is 
rarely as serious as the normal type of damping-off. Top damping is 
only of importance in cases of excessive and unusual atmospheric 
moisture, so far as the writer’s experience indicates. In the Middle 
West it has proved relatively insignificant. The three types which 


Hic. 5.—Nearly complete destruction of the seedlings of Pinus banksiana at an unusually 
early age, at Garden City, Kans. (Photographed by Dr. J. V. Hofmann.) 


occur after the seedlings appear above the soil surface can, of -course, 
be evaluated by frequent counts during the damping-off season. This 
has apparently not yet been done by anyone. However, in experi- 
ments on damping-off control by soil disinfection, data have been 
obtained on comparative emergence (number of seedlings appearing 
above the soil surface) in treated and untreated plats and on the total 
parasitic losses after the seedlings appear which permit a certain 
amount of analysis of the losses due to damping-off parasites. The 


data from five nurseries bearing on this point are presented in 
Table I. 


ube BULLETIN 934, U. S. DEPARTMENT OF AGRICULTURE, 


TABLE I.—Relative importance of losses by damping-off before and after conife r 
seedlings emerge from the soil. 


Basis. Loss in control plats. 
Number of | - Emerged at 
Nursery and species. Series. plats. (viable seeds). ore \ 
Disinfectant: |—————_ > >| = sca 


ee 


to= 
Treat-| Con- | Be- After./Total. col.7. 


ed, /trols.| fore. 


ne 2 3 a | & |e yee 
Bessey (Nebraska sand hills): Pict. \ PCCP SCE. a. 
Pinus banksiana. .......... Average of 9....| Sulphuric acid} (ca) (b) | 37.8 |¢€27.2 | 65.0) 1.39 
ponderosa. oe Aweraceof2. 42) dese 6 8 | 28.1 | 27.3 | 55.4 | 1.03 
MESIMNOSAS: sete See Average of 3....|.... O22 sos 4 7 | 29.4 | 54.1 | 83.5 . 54 
Garden City (southwestern 
Kansas): 
Pinus ausitises: cee Average of 2.... COBPes sul- 4 3 | 69.0 | 27.5 | 96.5 | 2.52 
phate. 
Pinus banksianias as .e seer eee do: ees Zine chlorid. .. 3 2 | 80.7 | 12.0 | 92.7] 6.72 
Pinus ponderosa........... Average of 7....| Copper — sul- 17 29°) 15.3 | 30.9 | 46.2 .49 
phate. 
Cass Lake (northern Minne- ; 
sota): INO 10be asec Formaldehyde 6 3 | 3.8 | 37.2 | 41.0 . 10 
INO: 10525) eee eee Goro bee 6 3 | 25.7 | 36.2 | 61.9 é bc 
. : Notl053. os - - Zine chlorid. .. 4 4} 5. 712652 (3L9 : 
Pinus resinosa.............. Nas 1054.20. 5 odes Bisa 4| 3) -7ial-ag ee eee, 18 
Nos. 1057 and | Heat.2........ 4 2) 4.9] 16.9 | 21.8 . 29 
: 1061. 
East Tawas (Michigan): , 
: : UD ee Pee Formaldehyde 6 3] 5.9 | 45.3-| 51,2 . 13 
Pinus resinosa.............- (i078 oe e ee Sulphuric acid 2 7 | 58.2) 18.0 | 76.2) 3.25 
Nos. 791 and | Formaldehyde 7 8 |.12.6 | 36.1 | 48.7 .35 
Fort Bayard (New Mexico): 792. 
Pinus ponderosa.......-..: Nos. 891 and | Sulphuricacid 8 6 | 14.5 | 18.6 | 33.1 . 78 
892. 


a Area counted, 122 square ey b Area counted, 78 square feet. 
¢In Pinus banksiana at the Bessey Nursery, the loss after emergence is slightly low and the ratio slightly 
high, because of the closing of counts on afew of the series before damping-oft was entirely over. 

The procedure was to average the number of seedlings which 
emerged in the control plats in each series and subtract this number - 
from the average number emerging (that is, appearing above the 
soil surface) in the treated plats in the same series. The treated 
plats chosen were the ones which allowed the averaging of the 
greatest number of plats treated with the same disinfectant. Only 
those plats were taken in which there was no evidence of injury to 
the seed or seedlings by the disinfectant and in which the amount 
of normal damping-off during the first few days after emergence 
was so slight as to indicate satisfactory initial control of the parasites 
by the treatment. In such plats it was assumed that the germination - 
loss was unimportant, and the average number of seedlings appear- 
ing on them was taken as representing the number of viable seeds per 
plat. The difference between this emergence figure and the average 
emergence in the controls was taken as indicating the extent of para- 
sitic loss before the seedlings appeared, including any destruction 
of dormant seed by parasites which may have occurred as well as 
the killing of germinating seed. Both this figure and the number 


DAMPING-OFF IN FOREST NURSERIES. 13 


of seedlings which succumbed to damping-off after emergence were 
reduced to a percentage based on the indicated number of viable seeds, 
and they are directly. compared in columns 6 and 7 of Table I. At 
three of the nurseries the data of the same species of pine and with 
the same treatment were averaged. 

The data in Table I do not indicate any regularity either in the 
extent of loss before emergence, the loss after emergence, or in the 
ratio between these 
two values. For ob- 
vious reasons, no reg- 
ularity is to be ex- 
pected in any of these 
items. The table is 
of some interest, 
however, in confirm- 
ing the evidence of 
the inoculation ex- 
periments, of obser- 
vation of sprouting 
seed dug up in the 
beds, and of the par- 
tial or complete fail- 
ure of emergence at 
the centers of large 
damping-off foci 
(figs. 4,7, and 8) that 
the work of parasites 
before the seedlings 
appear may in some 
cases be of consider- 
able importance. It 
is obviously impos- 
sible to make any 
general quantitative 
statement of the se- 
riousness of such loss, 


: ‘ : Fic. 6.—Root sickness in Pinus nigra poiretiana. The two 
in vlew of the varla- seedlings at the right are healthy. The three at the left 


: : : have had their taproots decayed to within 13 inches 
tion in its extent at of the soil surface. All are putting out lateral roots from 
different times and the lowermost sound point. Similarly injured seedlings 
: ] ived isf g . 
places and of the in- when transplanted lived and made satisfactory growth 


accuracy of any computations based on the relative emergence 
of hosts as irregular in their germination as the conifers are 
known to be. The case is complicated in addition by the fact 
that, despite careful avoidance of treated plats known to have 
suffered chemical injury, it is probable that a few seedlings were 
killed before emergence by the disinfectants used in some of the 


14 BULLETIN 934, U. S. DEPARTMENT OF AGRICULTURE. 


cases. It may furthermore be that in other cases the disinfectant had 
a stimulating effect, resulting in better germination in the treated 
plats, entirely aside from that resulting from parasite control. The 
number of disinfectant methods which concurred in giving apparent 
increases in germination, however, makes it seem reasonably cer- 
tain that no great part of the increase was due to this stimulation. 
- In addition to the different disinfectants shown in the table, mer- 
curic chlorid, heat, hydrochloric acid, nitric acid, and ammonia all 
apparently resulted in approximately the same increases of germina- 
tion in tests at the Bessey Nursery as the sulphuric acid which was 
used as the standard for comparison in most of the series. Relative 
emergence in treated and untreated plats, as well as damping-off 


Fic. 7.—A clean-killed area in a bed of Pinus ponderosa, caused by Corticium vagum, 
Inside a 12-inch circle at the center of this ‘‘ patch” no seedlings appeared. It will 
be noted that the weeds as well as the pines have been killed with the exception of 
Salsola tragus. 


loss after the seedlings appeared, was determined at two nurseries 
in addition to those given in the table. The results at these nurseries 
in general confirmed those at the five nurseries covered by the 
table in showing lower emergence in the controls. Although it is 
impossible to draw positive conclusions, some idea of the seriousness 
of losses before the appearance of the seedlings above ground can be 
obtained by studying the data in Table I. The fact that such losses 
appear considerable, sometimes exceeding the losses from the damp- 
ing-off that occurs after emergence, is believed to explain the com- 
mon failure to secure satisfactory results from. control measures 
taken after the seedlings have come up and the disease has become 
noticeable. It is somewhat interesting to note that the data in the 


| 


ws 


: 
: 
| 


DAMPING-OFF IN FOREST NURSERIES. 15 


table tend to confirm field observations that, as compared with other 
species, Pinus resinosa is more susceptible to the later forms of 
damping-off than to germination loss. 

Further indication that the killing of germinating seed before 
emergence may be important enough to help explain cases of poor 
germination is obtained by an entirely different method, as follows: 
At the Wind River Experiment Station of the United States Forest 
Service counts of the seedlings emerging and of those which later 
died were made on a number of untreated plats by forest officers, 
who kindly permitted the writer to use the data obtained. The 


‘counts were made separately on 10 plats each of noble fir (Abies 


nobilis) and silver fir (Abies concolor). The plats of each species 
had been sown with equal quantities of seed. It appeared on in- 
spection of the figures that the plats which showed the poorest emer- 


Fig. 8.—The area shown in figure 7 after the bed had been weeded and damping-off had 
practically ceased. (Photographed by 8S. C. Bruner.) 


gence were also the ones which suffered the most subsequent loss. The 
coefficient of correlation between the number of seedlings emerging 
and the percentage of subsequent loss in the same plats was found 
to be —0.49+0.16 for the noble fir, and —0.50+0.16 for the silver 
fir, an average of —0.49+0.11 for the two species, confirming the 
conclusion drawn from inspection of the figures. In other words, 
poor emergence and heavy subsequent loss were in general associated. 
The simplest explanation of this association appears to be to suppose 
that both poor emergence and subsequent loss were largely due to 
the same cause, namely, the damping-off parasites. Another possible 
explanation of the correlation would be to neglect parasites as im- 
portant causes of the poor emergence in certain plats and to suppose 


that the higher subsequent loss in such plats was due to heat injury, 


the less dense stands affording less shade to the bases of the seedlings 
composing it. As damping-off is in general so much more important 
than heat injury as a cause of death after emergence and the dif- 
ference in the degrees of shade between the plats with the denser 


16 BULLETIN 934, U. S. DEPARTMENT OF AGRICULTURE. 


and the plats with the thinner stands must have been very slight, this 
latter explanation has not much to support it. The data are believed | 
to constitute further evidence of the importance of parasites in de- 
creasing the percentage of emergence in coniferous seed beds. That 
the effect of parasites on emergence should have been large enough 
in this case to make itself apparent on the face of the figures, despite 
the variations due to other sources, is especially interesting in view 
of the fact that the losses after emergence in these plats were not 
se ie ECONOMIC IMPORTANCE OF DAMPING-OFF. 
The importance of damping-off in coniferous nurseries in Europe ~ 
is indicated by frequent reference to the disease in the literature. 
Biittner (25, 26) states that whole beds are frequently destroyed by 
it. Baudisch (9) speaks of the death of entire stands in many 
nurseries as the result of damping-off. In the United States Spauld- 
ing (137) considers damping-off a serious obstacle in forestation 
operations. Clinton (28, p. 348-349) reports serious damage to 
conifers in New England nurseries. The writer has found the dis- 
ease especially prevalent in nurseries in Nebraska and Kansas, a some- 
what unexpected situation in view of the relatively dry conditions 
prevailing there. A correspondent has reported heavy loss in seed 
beds in Texas. | 7 
The economic importance of the disease in conifers is due in part 
to the rather heavy average losses experienced at many nurseries 
and in part to the irregular character of the losses. In one season 
losses may be negligible, while the next season the beds of certain 
species may be practically wiped out. Even without this element of 
uncertainty the losses experienced are expensive, because of the high 
cost of coniferous seed. The seed of some species costs from $3 to 
$5 a pound and seldom shows a germination of more than 60 per 
cent under nursery conditions. <A loss of half of this 60 per cent from 
parasites, both before and after the seedlings break through the soil, 


is therefore a matter which deserves attention. The figures in ~ 


column 8 of Table I, obtained by adding together those in columns 


6 and 7, show that the loss 1s frequently higher than this. At 


the nurseries at which control experiments have been conducted, the 
percentage of the seedlings in untreated beds which have been found 
by actual count damped-off after emergence is frequently more than 
50 per cent, in addition to the considerable but less accurately de- 
terminable loss indicated by the foregoing data as being caused by 
the parasites before the seedlings appear. 

It has been suggested by foresters and others that the net economic 
damage from damping-off is not as great as is indicated by the loss 
of seed and seedlings which it may cause. The argument is ad- 


Q 
a 
S 
: 
Zt 
w 
S 
S 
x 
XS 
% 
S 
P| 
; 
2) 


. ¢ 
DAMPING-OFF IN FOREST NURSERIES. 


* saeeeee" 
oor" 


o- 
oo" 
Fag 


eee pets Bek e 


8 


COPPER SALTS 


100}- 
74 
60 
90 
20 


FORMALDEHYDE | SULPHURIC ACID 


SULPHURIC AC/D 


70. 20 30 30 sO "70. 20. GO FO SO 
DAYS SINCE GERMINATION 


Fic. 9.—Diagram showing the progress of damping-off in treated plats 


(solid line) as compared with untreated plats (broken line). Graphs 
1 to 4 represent Pinus ponderosa; graphs 5 to 8, P. resinosa; graph 9, 
P. banksiana; and graph 10, plats each of which was half P. nigra 
poiretiana and half P. sylvestris. Nurseries in Kansas, Nebraska, Minne- 
sota, and Michigan are represented. The relatively high total number 
damped-off in the treated plats shown in two of the graphs is due to the 
fact that a large proportion of the seedlings in the untreated plats had 
been killed before they appeared above the soil surface. In both the 
cases in which the absolute number of seedlings killed was as great 


“in the treated plats as in the controls, the percentage of the seedlings 


killed was nevertheless lower and the survival more than twice as good 
as in the controls. 


19651°—Bull. 934—21——2 


17 


° : & 
18 BULLETIN 934, U. S. DEPARTMENT OF AGRICULTURE. 


vanced that damping-off may be a valuable selective agent in nursery- 
grown stock for forest planting, eliminating the weaker individuals 
and thus insuring the vigor of the trees which go into the forest 
plantation. This is a possibility which must be considered. It is by 
no means certain, however, that escape from damping-off is correlated 
with permanently superior vigor. It is believed that temperature, 
moisture, and other environmental factors, which as yet are very im- 
perfectly analyzed, together with the age of the seedlings and the — 
presence or absence of virulent strains of-the parasites, are much — 
more important factors than inherent differences in individual re- | 
sistance in determining whether or not seedlings are destroyed. Evi- 
dence from inoculation experiments and from field observation, sup- 
ported by data of the sort presented in Table I, indicate that damp- 
ing-off ordinarily does a considerable part of i damage by killing 
the sprouting seed before emergence from the soil, while the graphs 
in figure 9 show that of the Ss) which occurs nee emergence in un- 
treated beds a large part occurs very early in the life of the seedlings. 
Observation of the clean sweeps which the disease commonly makes 
in the immediate neighborhood of infection foci (figs. 3, 4, and 5) 
indicates that either before or just after the seedlings ree tigeuch 
the soil none of them have any considerable resistance to the really 
virulent strains of the parasites, which are believed to be the ones 
responsible for the major share of the damping-off. 

Even if there should be found to be an appreciable selective value 
in damping-off, this would not be a valid argument against control 
by seed-bed disinfection for the following reason: The graphs show- 
ing the course of damping-off in treated plats in figure 9, together 
with the decided differences in germination between treated and un- 
treated plats, indicate that the very early damping-off is more com- 
pletely controlled by disinfectants than the later damping-off. This 
early damping-off which the treatments so largely prevent is the 
part of the loss which has the least possibility of selective value. 
The later damping-off is rarely controlled at all thoroughly by disin- 
fectants. As shown by the graphs, it is often even heavier on the 
treated than on the untreated soil. It is the part of the loss which 
is most likely to have selective effect. At this stage beds are not 
taken clean, as earlier; only seedlings which are below normal re- 
sistance succumb. The damping-off in disinfected beds seems there- 
fore at least as likely to have true selective value as that which 
occurs in untreated beds. 

The only way in which the effect of damping-off as a selective 
agent can be positively determined will be to compare through sev- 
eral subsequent years the growth rate, or survival after transplant- 
ing, of trees from beds ae aut seriously from damping-off 
with the growth of trees from the same lot of seed in seed beds in 


“= enue ok 


eee a Ss ls ee eee Tt 


a a 
' 


eS ——E——E————— ee = 


DAMPING-OFF IN FOREST NURSERIES. 19 


which the disease is either accidentally absent or is artifically con- 
trolled. Such an experiment is within the silvical rather than the 
pathological investigative field. If it be found that there is some 
selective value in the action of the disease and that it is greater in 
untreated than in treated beds, it would still seem that a much more 
desirable and dependable selection could be obtained by discarding 
weak plants at the time of transplanting than by letting damping- 
off run uncontrolled in the seed beds. Damping-off is sometimes 
negligible and sometimes destroys practically all the seedlings in a 
given area, in neither of which cases can it have any material selective 


value. 
RELATIVE SUSCEPTIBILITY OF DIFFERENT CONIFERS. 


Biittner (25) writing of European conditions, states that exotic 
conifers are especially subject to damping-off. He includes fir, 
spruce, pines, larches, and cypress in this statement. He mentions 
the same subject in a later paper (26). Neger and Biittner (94) give 
a long list of different species of conifers from various parts of the 
world with statements as to their susceptibility to damping-off. 
Beissner (11, p. 656-657), Neger (93), Clinton (28), Bates and 
Pierce (7), Boerker (13), and Tillotson (139, p. 69) have all given 
information on the susceptibility of different conifers. The data re- 
ported by Tillotson are drawn from reports by various officers of the 
United States Forest Service which he has compiled. While it is 
probable that the nurserymen who are responsible for most of his — 
records have not observed the disease as closely as Neger and Biittner, 
the fact that their observations are mostly based on repeated seasons’ 
work with large-scale seed beds of the species they report on makes 
their observations in some respects more reliable than the other pub- 
lished data. Neger and Biittner presumably worked in most cases 
with small beds of the various conifers on which they report, and the 
variations which they attribute to differences in specific resistance 
might easily in such case be largely due to accidental variation. The 
error which nurserymen are most likely to make in their notes on 
susceptibility is to underestimate the loss, especially for the small- 
seeded species. The seedlings of small-seeded conifers decay and 
shrivel so quickly after they fall that in taking notes at any one time 
only a small proportion of the total loss is visible. Frequent counts 
of dead seedlings are the only way by which the loss after germina- 
tion in such species can be properly appreciated. 

The data given by the authors mentioned in the foregoing para- 
graph, together with unpublished data obtained by personal observa- 
tion or from commercial and other nurserymen in the United States, 
are summarized in Table II, the source of each report being shown 
by letters signifying the authority. The unpublished data on two 


20 BULLETIN 934, U. S. DEPARTMENT OF AGRICULTURE. 


nurseries in Illinois and Minnesota were obtained from the nursery- | 
men by Mr. R. G. Pierce and are indicated by the initial “P.” In- 
formation obtained directly from the nurserymen by the writer is in- 
dicated by “N.” For nurseries where the statements are based on 
the writer’s personal observation rather than on the authority of the 
nurserymen, his own initial (‘““H”) is given. Most of the writer’s 
own estimates of relative susceptibility are based on a comparison 
of detailed counts of the damped-off seedlings in a large number of 
untreated plats at different times, as well as on observation. The 
nurseries on which Tillotson reported were all west of the Missouri 
River, most of them being in the mountain region. The reports in- 
dicated by “H” and “N” were mostly from nurseries east of the 
Rocky Mountains. In cases in which the data permit it, the species 
are classified as most susceptible, intermediate, least susceptible, or 
immune. Ina number of cases, however, it is only possible to classify 
them as “more” or “less” susceptible. 


TABLE II.—Relative susceptibility to damping-off of different conifer species. 


[Figures in parentheses in this table indicate the number of nurseries from which the susceptibility noted 
- has been reported by the observer to whom the preceding letter refers. ] E 


Reports of relative susceptibility.6 


Host species. Not | Least hans Inter- | More sus- Mast 
sus- sus- co melt ceptible 
A edi- suscep- 
cep- | CeP- | average. | ate than the | “tiple 
tible. | tible. Be. £ average. $ 
Pinacez (Abietoidee): F 

ADIES- SPP ooo ce se ho be ees See ne eee eee ee (C2) een PP ee ee 
Abies balsamea:<.2s4.. aise ea oss. oe eee ND.2 25). 22.22000<l|.55. 20a 
Abies cephalonica. - 2.000... os esse seen eee lee eee eee Nb: .2¢\ce. coe 
Abies .concolor's...<- ce. tc84-4 es eee [-sa-cde-|oc-- peas =. wece- dpaee eee aan Bu, Nb. 
Abies nobilis... 8.3 tees eee eee [aes ae oo PE TY. oes ool one See fs 
Abies nordmanniana: 2 2228 22.24 322 eee a ee ee ee Nb.o2:|33-. ree 
Abies picea: (A. pectinata)s.- ——. 2ache tee see eee eee ee eis awe se ND.«;2 |ooeec eee 
Abies sacchalinensis (2) .aass22 . snows ence a leeeee bee ose eee Hee. Seeee Nbtc3|25) eee 
A Dies Sibiti@a >. .. =<... se en eee eee Nb... 3. |.252- +0 «<0l 06 eee eee 
Abies veitchii..........5..9...-..c0 9222 2c\e S0a 222 |th J gael ees 22 eee Nb. 
Cedrus deodara-=..... < 0sce =... See eee eee |e eee i) en ete 
Larix europea. toca. oss ayer 1 da oe ee oe ao ee eee Nb:. =}, ING@)22 see 
Larix leptolepis<- .. 2.2. 2022.2... 2022-20) oem cess |e ne eee eee = ee ee Nb. 
Larix oecidentaliss.. ) =. see ee Beri eaery eer’, .*- ho ee Ts eee 
iced Bjaneysis. |. 2. cee oe ae eee te ee Vek ee soto, «ee ha Nb... |. seceeeeeeee 
Picea canadensis £32. J57 assesses aes ee 2 oN eee N bose eee Pega Nise ees 
Picea engelmannt’ co. sac seee eee Sa raceel i. = ae TY (2). 53le ee ay , Ne, | Nb. 
Picea @XCelsSass.. 25. a eee ee i See Nb teal, But 4l-eeeeeee Nex Ne gee 
Picea omorika:...... 20.28 Ase seen ee eee oe Ne 342. Nb: ... |) 2. eeeeee 
Picea orientalis... 32.2 --ce see Pes cee weds cles wecceslecce need! INGs oe cs =a Nie |e 
Picea puNngens: <2). . aca seee Sete 6 eee ee eee eee INO) eee H, P.i}Nestpicee N ne 
Picea sitchensis..,.,.. .2..002 3:2) 2Seacss. 42224) a2. ele. See eee eee Ne 222 94: N 
Pinusianstata.2_° ') coh .de se eee eee ee NDenoc| foe 2 as os sins eee eee 
Pinus attenuata... .. . 0. weds oo sw afdoehe a acceccllen 2. cael eke euler © eee een 
Pinus bankers .°: ..-- 538, ee ee ee oe ee NDS SS soe Pie B, % H} BoE 
Pinusicontortas 2. 922.2. 6 cee ee Tock] NDS ee 3 or pees eee eee Ot te 
IPIintisiOG@uliss tees Fe eo ho soe eee / es a eee |e 


a Host names for American species follow the usage in the publications and a later verbal communication 
of Mr. George B. Sudworth, of the United States Forest Service. For exotic species the Standard Cyclo- 
pedia of Horticulture, New York, 1916,edited by L. H. Bailey, is taken as the standard. The classification 
follows Saxton (118). : 

b Symbols signifying the authority for the report: B= Boerker (13), Bu=Biittner (25, 26), Bp= Bates 
and Pierce (7), C=Clinton (28), H= Writer’s estimate, N= Nurserymen’s estimate (obtained by the writer), 
Nb= Neger and Biittner (94), Ne= Neger (93), P= Nurserymen’s estimate (obtained by Pierce), T= Forest 
officers’ estimate (compiled by Tillotson, 139). f 

c Susceptibility to Phytophthora fagi. 


DAMPING-OFF IN FOREST NURSERIES. 21 


TABLE II.—Relative susceptibility to damping-off of different conifer 
: species—Continued. 


Reports of relative susceptibility. 


More sus- 
ceptible 
than the 
average. 


Not 

sus- 

cep- 
tible. 


Least 
sus- 
cep- 

tible. 


Host species. Inter- 


medi- 
ate. 


Less 
than 
average. 


Pinaceze (A bietoidex)—Continued. 
Pinus excelsa 
[ECT G TCO S > a i Se ene ee ee (de Se 
Pinus jéfireyi 
Pinus lambertiana 
Sean emrrieatNe AAP TENTS 3 ac oe rn wn twain aw ma a olla 2 ae gece a cine aces 2 
insmmonticola.- 2. 2....3.2..2...5.4. 00. 
Pinus nigra austriaca (Austrian pine)... 
Pinus nigra poiretiana (Corsican pine)..-.| Bp 
OU. UST STNG)... 2 i a ee | (eee ee ek) (ela ease 
[MMe 0000/5245. 45 398 095 Soe ae ee 
Pinus ponderosa (type not specified) 


Pinus ponderosa (Eastern Rocky Moun- 
tain type) 
Pinus ponderosa (Pacific coast type) 
DUE DSS ein oo Sees ae ee org ae ee ee) eee 
Pus ThE. | Se eee |e ceet por! (ae imams 
Pinus strobus 
Pinus sylvestris 
Pinus taeda 
Pinus thunbergii 
Pseudotsuga taxiflolia (type not specified ). 
Pseudotsuga taxifolia (Colorado type). . - - 
Pseudotsuga taxifolia (Northwestern 


Number of reports 
Percentage of total 


Sciadopitoidez: 
Sciadopitys verticillata.................-- 
Cupressaceze (Cupressoidex): 


Chamaecyparis lawsoni 


Chamaecyparis pisifera. 


Cryptomeria japonica 
Cupressus spp 
Cupressus arizonica 
Juniperus communis 
Juniperus monosperma 
Juniperus pachyphloea 
Juniperus virginiana 


ana 


Libocedrus decurrens 


Damper GIstienap95. 22522-2422... 
Thuja Den leniie) ha a 
Thuja orientalis 
Thuja plicata 


Ses iP Bee ees eee i 8 eee ee ee ees 


Number of reports 
Percentage of total 


Sequoidez: 
Sequoia spp 
Sequoia washingtoniana 

Taxacese: 

Taxus cuspidata 


The fact most evident in Table II is the extreme variation between 
reports, not only on closely related species but even on the same 
species. While it is, of course, possible that the obvious lack of a 
definite basis and method of comparison in most of. the reports is 
responsible for most of this variation, it seems to the writer more 
probable that different species do actually vary in their relative sus- 
ceptibility to damping-off in different localities. In the first place, 


22 BULLETIN 934, U. S. DEPARTMENT OF AGRICULTURE. 


the conditions which might increase resistance of one host might 
very easily decrease its resistance for a host with different environ- 
mental requirements. To. illustrate by an extreme example, the 
pinon (Pinus edulis) of the arid or semiarid region might remain 
resistant in soils in which Picea engelmanni of the high mountain- — 
stream bottoms or Picea mariana of the northern swamps might be 
low in vigor and easily attacked. In the second place, it is to be 
expected that species with a certain order of relative susceptibility to 
the parasites which predominate at one.nursery may exhibit a very 
different order of susceptibility to the different combination of para- 
sites which might be prevalent in another locality. 

The only individual species on which there are a sufficient number 
of reports and a sufficient agreement between the reports are the two 
common western spruces, Picea pungens and P. engelmanni, which 
(at least as compared with Picea'excelsa) seem rather susceptible, 
and Pinus ponderosa, which (as compared with most of the other 
species of the Abietoidez) is to be regarded as generally more re- 
sistant than the average. Within each of the larger genera of this 
group it seems evident that susceptibility is extremely varied and 
that no statement as to the relative susceptibility of the genera them- 


selves can therefore be made. The only group generalization that 


is perhaps permissible is derived from the consideration of the 
Cupressoidex. In this group, out of 23 reports, 16 are in the “ not. 
susceptible” or “least susceptible” columns and only one indicates 
more than intermediate susceptibility. Of 163 reports pertaining 
to the Abietoidex, only 26 place them in the “not susceptible” or 
“least susceptible” columns and 63 in the classes of more than inter- 
mediate susceptibility. The general feeling among nurserymen 
seems to be that serious damping-off need not be feared among the 
cedars and their relatives. The data at hand tend to justify this 
confidence. | 
CONTROL OF DAMPING-OFF. 


Early efforts to prevent damping-off were chiefly directed to the 
avoidance of excessive moisture in either the air or soil. A means 
to this end, which has been observed more or less by nurserymen for 
many years, both in the United States and elsewhere, is the applica- 
tion of small quantities of dry sand to the seed beds after the disease 
becomes noticeable (18, p. 166; 83). ‘This is sometimes applied hot 
(101, p. 43-44; 145), though even this procedure does not result in 
very great advantage. Surfacing with hot sand can not always be 
counted on to give any measurable advantage over untreated beds (67, 
p. 8). The use of sand (25) or sterile subsoil (101) instead of ordi- 
nary soil in covering seed at the time of sowing has been advised. 
Johnson (82) did not secure satisfactory results with sand in tobacco 


PE ee 


DAMPING-OFF IN FOREST NURSERIES. oe 


beds. Making the upper part of the bed to a depth of several inches of 
recently dug subsoil appeared effective in a single test by Spaulding 
(137) and at four nurseries by cooperators of the writer in later 
tests, the results of which will be published elsewhere. The procedure 
is unfortunately rather expensive in large-scale work and under some 


' conditions at least undesirable because of the poor subsequent growth 
-on such soil. Excessive vegetable matter (45), imperfectly rotted 


manure (67), or green manures recently plowed under (43) have all 
been advised against as likely to favor the disease. The experience 
reported with conifers (67, 139) indicates that damping-off can be 
to a certain extent decreased by broadcast sowing as compared with 
sowing in drills. The usual recommendation of thin sowing to avoid 
the seed-bed disease of other plants has also been made for conifers 
(67). Transplanting healthy seedlings from infected beds into new 
soil is recommended as a means of saving them from attack (11, 145). 
The writer’s tests of transplanting at a Nebraska nursery gave no 
promise of economic value as a control method, although he is in- 
formed that it was successfully employed in a nursery in New Mex- 
ico. The time of sowing appears to have a relation to the amount of 
disease at some nurseries, but conditions in this regard evidently 
differ in different localities, so that: the best time to sow from the 
standpoint of avoiding damping-off must be determined separately 
by repeated tests at each nursery. For example, observations both 
by the nurserymen and the writer during several seasons at the 
Bessey Nursery, in Nebraska, indicate that fall sowing is an ex- 
cellent means of decreasing loss from damping-off in at least one 
pine species, and Retan (110) reports the same thing for a nursery in 
Pennsylvania, while at two Kansas nurseries and at nurseries men- 
tioned by Tillotson (139) fall-sown beds suffer more than those 
sown in the spring. 

Treatment of the seed with mercuric chlorid (25) or with copper 
sulphate (122) has been recommended. While it has been demon- 
strated (38) that a proper heat treatment of the seed will greatly 
decrease the damping-off in sugar-beet seedlings, this is explained 
by the fact that one of the most important parasites of the sugar 
beet is systemic and often present in the seed. There is no reason 
to believe that seed-carried infection is of any importance in conif- 
erous seed beds. The only advantage that could reasonably be 
expected from a seed treatment of conifers would be that which 
would come from the prevention of seed decay in the soil before 
germination starts, and this protection could be expected to be ef- 
fective only if a relatively insoluble disinfectant, such as Bordeaux 


_ mixture, was used. 


Soil treatment is the most direct and probably the most profitable 
method of attack on the disease. It is especially easy, for tobacco 


24 BULLETIN 934, U. 8. DEPARTMENT OF AGRICULTURE. 


seedlings (82) as well as for pines, to prevent by soil disinfection 
losses before the seedlings appear above the ground. Heat disinfee- 
tion of seed beds has been frequently mentioned. Burning wood 2 
or litter on the surface of the beds before sowing, said by Gilbert (47, 
p- 36) to be a common procedure in preparing tobacco seed beds both | 
in Italy and in parts of this country, has been recommended for’ 
coniferous seed beds by Biittner (25). The disadvantageous results | 
sometimes noticed following the application of wood ashes to pine 
seed beds may prove an objection to this type of treatment in some 
of the nurseries. At a Nebraska nursery (67) moist heat proved only 
partly satisfactory, unavoidable reinfection having serious results. 
Steam disinfection, using the inverted-pan method commonly advo- 
cated for tobacco seedlings (10, 47, 81), has been reported by Scott 
(123) as successful at a nursery in Kansas. Gifford (46) found 
steaming with the inverted pan only partly satisfactory. It is not 
believed that it is likely to pay to install the necessary apparatus for 
steam disinfection at nurseries in nonagricultural districts where 
steam tractors are not available for temporary use. The hot-water 
soil treatment as used by Byars and Gilbert (27) is probably worth 
a trial at any nursery where damping-off is serious and fuel cheap. 
It may be that in some localities where steam-or hot-water treatment 
of the soil is not sufficiently effective, its efficiency can be increased 
by reinoculating the soil immediately after treatment with sapro- 
phytic molds and bacteria to provide maximum competition for 
parasites which come in from the outside. Tests of this procedure 
will be described later in the present bulletin. The value of char- 
coal has been emphasized by Retan (109, 110). 

Chemical disinfection of the soil has also been employed. Sulphur 
has long been in use as a soil treatment against the damping-off of 
various plants (45, 111) in addition to its use in combating potato 
scab and onion smut. It was tested on conifers by Spaulding (136, 
137) in the form of light surface applications to the beds after ger- 
mination, but without decisive result. In later cooperative tests pow- 
dered sulphur raked into the soil before the sowing of the seed failed 
to indicate any large measure of value. Very finely divided forms 
of sulphur in various amounts and times of application are prob- 
ably worth some further test. 

Moller (90) and Sherbakoff (128) have reported the successful use 
of copper sulphate in combating attacks of Corticium on dicotyle- 
dons. In Johnson’s a SR on tobacco seedlings (82, table 
3) copper salts and Bordeaux mixture were the only chemicals for 
which any value was indicated. Sherbakoff apparently used copper 
sulphate and other strong disinfectants chiefly to stop the extension 
of vigorously spreading damping-off foci by local treatment rather - 
than as a general treatment for use over the beds. Such treatment 


DAMPING-OFF IN FOREST NURSERIES. 25 


would presumably kill all seedlings on the area treated, but would, 
of course, be of considerable value in stopping’ at the outset such 
mycelia as those which caused the damped-off area in figure 7. The 
procedure would be of practical value only in cases in which damp- 
ing-off was chiefly limited to a few large patches of this sort, a rather 
rare condition in conifers. 

Copper sulphate solutions have been used on pine seed beds at the 
time of sowing with considerable success at some nurseries (65, 67). 
Except in a nursery in which the soil contained carbonates, it has 
proved rather difficult to prevent injury to the pines. The trial of 
some such combination of copper sulphate and lime as was used 
by Spaulding (136) on the surface of pine beds before sowing, which 
apparently prevented the damping-off of lettuce in some unpub- 


_ lished pot experiments of Mr. J. F. Breazeale,.is considered desir- 


able. Treating seed beds with ordinary Bordeaux mixture has also 
been recommended. Horne (78) secured especially good results 
against Corticium vagum in tobacco seed beds by heavy applications 
of Bordeaux mixture, and Schramm (122) and Clinton (28) have 
obtained indications of its value as a spray in preventing the damp- 
ing-off of conifers. It is probably worth further tests in various 
amounts of application. In tests conducted by the writer in 1912 
and still unpublished, some advantage was indicated for Bordeaux 
mixture as a surface treatment after soil disinfection with acid. 
Zinc chlorid as a soil disinfectant has also been found valuable in a 
number of cases (65, 67), but it is more expensive and apparently less 
dependable than copper sulphate. 

Formaldehyde and sulphuric acid have been ‘tested more fre- 
quently than other disinfectants. The use of sulphuric acid on 
coniferous seed beds was originated by Spaulding (136). The first 
intensive experiments with this acid were reported by the writer (63). 
The first experiments with formaldehyde on conifers seem to have 
been in the early greenhouse tests of Spaulding (137), repeated in 
forest nurseries in 1907 by Jones (83) and Spaulding (136). Most 
of the experiments with these two substances have already been sum- 
marized (67). A report not mentioned in this summary is that of 
Schaaf (119, p. 88), who obtained favorable results with the acid. 
The great trouble with formaldehyde is its tendency to kill dormant 
seed. The length of time which must be allowed to elapse between 
treatment and sowing in order to avoid this killing varies with con- 
ditions. Formaldehyde is more expensive than acid and seems on 
the whole to have been less effective in disease control. Acid, on the 
other hand (applied just after the seed is sown, which is found to be 
the best time), on a few soils has caused injury to radicles, which it was 
at first thought could be prevented only by very frequent watering 


-. during the germination period; while in a few cases, when cold 


26 BULLETIN 934, U. S. DEPARTMENT OF AGRICULTURE. 


weather resulted in a lone germination period, it has killed or in- 


hibited the germination of some of the dormant seed. All injury 
can be prevented by treatment a few days before sowing, followed 


by the addition of lime just before sowing, but lime used in this — 


way has apparently destroyed a considerable part of the value of the 
acid treatment against the disease. Further consideration of the 
data on which earlier papers (63, 67) were based indicates that the 
apparent need for frequent watering during the germination period, 
which was required at a few of the nurseries where the first tests of 
acid treatment were made, as well as-practically all of the germina- 
tion reduction, was due to the use of unnecessarily large applications 
of acid and that the trouble can be eliminated by determining by 
test the minimum quantity of acid which will be reasonably effective 
in each locality. If ‘this can be done it should establish the acid 
treatment as the most profitable for general use of any of the 
methods of damping-off control which have so far been extensively 
tested. 

In view of the various parasites which may cause damping-off at 
different times and places and which vary greatly both in their 
means of dissemination and in their physiological qualities, it is not 
believed that any single disinfectant will be found entirely satisfac- 
tory at all nurseries. It is also unfortunately true that no one 
strength of treatment can be recommended for all nurseries. The 
quantity of acid to be used at any specified nursery will have to be 
determined by test at that nursery. A single test, ‘no matter how 
well conducted, is not sufficient to serve as a basis for conclusions. 
However, a number of small-scale tests, made at different times and 
in different parts of the seed-bed area, should determine the. best 
treatment for any particular nursery with a reasonable degree of 
certainty and with very little work. If the plats are equal in size 
and receive equal quantities of seed, all the nurseryman needs to do 
to determine the value of the treatments is to count the number of 
liying seedlings on the different plats at the end of the season. The 
decrease in the number of weeds as a result of the use of acid is 
itself sufficient at a number of nurseries to pay the entire cost of the 
treatment. Detailed methods of application have already been pub- 
lished (67). The differing proportions of acid between which the 
best treatment will ordinarily be found to lie are 2 and 7 ce. ¢. (one- 
sixteenth and one-fourth of a fluid ounce) of the concentrated com- 


mercial acid per square foot of seed bed, applied just after the seed is 


sown and covered. It should be dissolved in 500 to 1,000 ¢. e. (1 to 2 
pints) of water per square foot of bed before applying. The drier 
the soil before treatment, the more water should be used in dissolving 
the acid. 

No treatment applied after germination begins can have the maxi- 


mum value in controlling the disease, because the damping-off para- . 


—— = wT 


Se ee a a, ee ewe ee 


DAMPING-OFF IN FOREST NURSERIES. o7 


sites frequently, if not usually, do part of their work before the seed- 
lings appear above the soil. Furthermore, any treatment at all effect- 
ive against the disease is almost certain to hurt the seedlings if applied 
after the seed starts to sprout. 

Both the acid and copper-sulphate treatments which have been 
found useful in pine seed beds are of very doubtful value for most 
hosts other than conifers, as the angiosperms on which observations 
have so far been made are too easily injured by the disinfectants. 
The weeds in the nurseries have been injured or entirely kept from 
appearing by treatments which caused no injury to the pines. 


CAUSAL FUNGI. 


CORTICIUM VAGUM. 


Occurrence and parasitism.—tIn a recent publication (68) Corti- 
cium vagum B. and C. (C. vagum solani Burt, Hypochnus solani 
Pril. et Del., the common damping-off Rhizoctonia) has been reported 
on a number of conifers. Inoculation, reisolation, and reinoculation 
on pine have established its parisitism on this host beyond a reason- 
able doubt, though in these inoculations, as in most, if not all, the 
work which has been done with the fungus on angiospermous hosts, 
the cultures employed have been from plantings of diseased tissue 
instead of from single spores. The inoculation experiments have 
confirmed the field observations indicating that this fungus is fully 
as able to cause loss by destroying germinating seed below the soil 
surface as to cause damping-off of the better known type after the 
seedlings appear above the soil surface. 

An extensive list of angiosperms on which the fungus has been 
reported is given by Peltier (98). Cross-inoculations between the 
pines (68), on the one hand, and potato (40) and sugar beet (38) 
have shown the same strains to be parasitic on both conifers and 
angiosperms and established the physiological as well as the morpho- 
logical identity of the fungus attacking pines with the common 
Cortictum vagum. Now that Duggar (34) has offered strong, 
though not yet entirely conclusive, evidence of the identity of C. 
vagum with the European “vermehrungspilz” (the MJoniliopsis 
aderholdii of Ruhland; 115) it is to be presumed that it is 
a cause of damping-off of conifers in Europe as well as in Amer- 
ica, though no reports of it on conifers have been so far en- 
countered in European literature. The Rhizoctonia reported by 
Somerville (132) on Pinus sylvestris and the Rhizoctonia strobi de- 
scribed by Scholz (121) ‘as killing young Pinus strobus were both 
on trees more than 4 years old, so that they had no relation to damp- 
ing-off. Furthermore, the first of these was apparently the old 
Rhizoctonia violacea, now known as 2. crocorum (R. medacaginis) , 
a fungus entirely distinct from Corticium vagum, probably belong- 


28 BULLETIN 934, U. S. DEPARTMENT OF AGRICULTURE. 


ing to an altogether different group of fungi and not known to cause 


damping-off of any host. /?hizoctonia strobi is not sufficiently de- 
scribed to allow determination of its identity. 

Variations in virulence——In the inoculations earlier reported on 
conifers, different strains of Cortictum vagum were said to vary 
greatly in virulence (68). Further examination of the data on 
which this statement was based yields confirmatory evidence. Part 
of this evidence is shown graphically in figures 1, 2, and 10. The 
experiments on which these graphs were based involved at the time of 
seed, sowing the addition to the soil of apparently pure cultures of 
C. vagum. Throughout each experiment the different units received 


PINUS BANKSEIANA PINUS RESINOSA 
1915 (915 1918 
EL 58 


ao | OE AS oo | wee 
414 I 

iS 7 

$/00 a” "4 


8 


SEFOLINGS GERMINATED PER 1001N 
° 8 


Fic. 10.—Diagram showing the relative activity of different strains of Corticium vagum, 
as indicated by the number of seedlings appearing in inoculated pots. Explanation of 
symbols :O =—Strain 147, from spruce seedlings, Washington, D. C., 1910; V =strain 
213, from sugar beet seedlings, Washington, D. C., 1911; [J—strain 230, from Hlaeagnus 
sp., Kansas, 1912; 0 =strain 233, from the same lesion as strain 230. Strains re- 
isolated from these, the results of which appear in experiments Nos. 71 and 72, are 
indicated by the same signs as the original strains used in the inoculations from which 
they were taken. The original strains in experiments Nos. 71 and 72 are indicated 
by arrows. 


equal quantities of seed, and the culture substratum used in inoculat- 
ing was the same for all strains. Experiments 36, 45, 47, 49, and 51 
were conducted on plats in out-of-door drill-sown beds, experiment 
36 on an alkaline soil, all of which had been heated in a moist con- 
dition at a temperature of not less than 80° C. for not less than 10 
minutes,” and experiments 45, 47, 49, and 51 on a sand which had 


2This temperature is probably high enough to eliminate damping-off organisms. Tests 
by Dr. Theodore C. Merrill indicate that the three most virulent parasites so far 
worked with are killed by placing agar tube cultures for 10-minute periods in water at 
the following temperatures: Pythium debaryanum, 65° C.; Corticium vagum, 50° C. for 
mycelium and 60° C. for sclerotia; Fusarium moniliforme, 70° C. Both the Pythium 
and Fusarium cultures contained spores. The possibility of the survival of oospores 
which would not be capable ef germination for several months was apparently eliminated 
by the writer, who retained Dr. Merrill’s heated Pythium tubes and made final transfers 
from them 74 months after heating, still without securing growth. Plenty of typical 
oospores were present in the part of the heated culture from which transfers were 
made, 


Se 


+ gle ili eas. 


a ae eS a ee ee, 


=e +. —_ — = 


— 


DAMPING-OFF IN FOREST NURSERIES. 29 


been treated with sulphuric acid followed later by lime. The other 
experiments included in the graphs were on autoclaved sandy loams 
in pots in the greenhouse. In these graphs are included all of the 
results in which the same groups of strains were used repeatedly in 
different experiments. In figure 1, the values plotted for experi- 
ments 36, 49, and 51 are for the number of seedlings which appeared 
above ground, the heavy inoculations and favorable conditions for 
damping-off in these experiments being such that even weak strains 
caused heavy losses and the survivals therefore do not give differ- 
ential results. Comparison of the survival data in the other experi- 
ments in figure 1 with the emergence data for the same strains in 
that figure and in figure 10 indicates that the strains best able to 
reduce survival are also the ones best able to reduce emergence. 
While the data presented in the graphs are not entirely consistent, 
it is very evident from them that strains 147, 213, and in a lesser 
degree 206 were regularly more virulent than most of the strains in 
tests conducted several years apart on different species of Pinus. 
It is also evident that certain strains of 186 and 189 which appear 
_ in figure 2 are quite regularly of low or doubtful virulence. Strains 50, . 
183, 192, 211, 212, 230, and 233, whose virulence is apparently inter- 
mediate, show a greater variability. In experiments 36, 45, 47, 49, 
and 51, in which conditions especially favor parasitism, they may 
cause practically as serious loss as the regularly virulent strains, the 
best differential results being shown in experiments in which the 
disease is less favored. The apparent variation in the relative viru- 
lence of such strains in different experiments may, of course, mean that 
their virulence is differently affected by different conditions. It 
seems rather more probable that the variation in relative activity is 
to be classed as accidental variation, necessarily great with small 
units which are subject to numerous uncontrollable variables. It 
seems entirely possible, however, that part of the observed differences 
in relative activity may be due to differences, not in virulence, but in 
the ability of the different strains to maintain themselves saprophyt- 
ically in different soils during the period between inoculation and 
the commencement of germination. For example, strains 230 and 
233 came from a nursery in southwestern Kansas in which the soil- 
acidity exponent, as determined by Dr. L. J. Gillespie, of the United 


States Bureau of Plant Industry, is 8.4. It seems entirely possible 


that these strains, rather strongly parasitic in some of the experi- 
ments, including an experiment on the soil from which they were 
taken, might prove less able than strains from some other habitats 
to maintain themselves on some of the eastern soils used in the green- 
house tests. The source of strains 230 and 233 was furthermore a 
locality where high soil temperatures are to be expected. The fact 


30 BULLETIN 934, U. S. DEPARTMENT OF AGRICULTURE. 


that experiments 71 and 72, in which they showed the least virulence, 
were conducted in a colder greenhouse than any of the other tests 
may have had something to do with the lower activity indicated for 
these strains. Variation in the temperature requirements of different 
strains in accordance with the temperature of the source locality has 
already been demonstrated by Edgerton (35) for one of the anthrac- 
noses. It is hoped later to determine the temperature and acidity 
preferences of these two strains as compared with the others used. 
It should be noted that the consistently weak strain No. 189 (fig. 2), 
was abnormal in habit, lighter brown, and produced fewer sclerotia 
than typical strains. The other strains appearing in the graphs 
showed no conspicuous morphological or cultural differences that 
were identical. The only other strain which was noticeably abnormal 
in culture was one from pine seedlings in Kansas, intermediate in. 
habit and color between No. 189 and the typical strains and indicat- 
ing little more virulence than No. 189 in the few experiments in 
which it was used. It does not appear in figures 1 and 2, but was 
included in the experiments reported in the following paragraph. 
Peltier (99) believes low sclerotium-forming capacity to be a sign 
of degeneration and low virulence; the writer’s experience agrees 
with his as to virulence, but these two strains showed no other evi- 
dence of lack of vigor. 

As a further check on the reality of the apparent differences in 
virulence between different strains, all of the original strains avail- 
able at the time, a total of 29, were used in the practically duplicate 
experiments 71 and 72 and the relative survivals of the same strains 
in the two series mathematically and graphically compared (fig. 11). 
The very decided correlation between the two experiments indicated 
by the graph has a coefficient® of 0.813-+0.042, nineteen times its 


The correlation coefficient, a very useful thing for many kinds of biological work, 
which unfortunately has received little attention from plant pathologists, is explained 
by Secrist (124, p. 43 et seq.) and the process of computation described (124, p. 453-467). 
A shorter method of computation is given by E. Davenport (30, p. 465-467); the 
example he gives is of a series with a large number of varieties, in which the correlation 
table is employed. Davenport’s method is, however, just as useful in such a case as 
this, in which the number of varieties is too small to make the formal table advantageous. 
In such a case the computation should be arranged as by Secrist (124, p. 460-461), but 
the guessed rather than the true mean used and Davenport’s formula employed. If the 
coefficient is +1, the correlation is perfect; if it is 0 there is no correlation, and if 
—1, perfect negative correlation. The significance of a coefficient less than 1 is judged 
from its relation to its probable error. King (84), in an excellent discussion of cor- 
relation, gives rules for judging the degree of significance of the coefficient. The 
correlation coefficient has its greatest potential usefulness in examining apparent causal 
relations. It is so used in connection with the relation between the hydrogen-ion exponent 
and damping-off in considering figure 12 of the present bulletin. Interexperimental, 
or, aS Harris calls them, “interannual” correlation coefficients of the sort used for 
these Corticium strains have been used by Norton (96, p. 51) in measuring the constancy 
of rust resistance of asparagus strains, by Harris (54) in demonstrating the constancy 
of differences in various characters between strains or individuals, and they appear to 
be useful for this purpose in the present case. 


DAMPING-OFF IN FOREST NURSERIES. 31 


probable error. Peltier’s results permit similar correlations for the 
18 strains common to his experiments 1 and 1A on carnation cuttings 
and for the 22 strains common to experiment 1 on cuttings and ex- 
periment 2 on seedlings. The coefficients found are decidedly lower 
than those obtained from the experiments on pine, 0.51+0.117 for 
the experiments on cuttings and 0.86+0.124 for the comparison 
of the results on cuttings with the results on seedlings, but neverthe- 
less indicate some interexperimental correlation for the same strains 
and therefore inherent differences in parasitic ability between the dif- 
ferent strains. | 


a 


e.g. 8 


8 


SEEDLINGS SURLUIVING PER 3POT UNIT 
~ 
ie) 


SESE EES Set LEEEREECEEEEEEE 
STRAINS OF COR?TIC/UM LAGUM 


Fic. 11.—Diagram showing the comparative virulence of 29 strains of Corticium vagum 
in two successive inoculation experiments on Pinus resinosa. The results in experiment 
No. 71 are shown by the solid line, the strains being arranged from left to right in the 
order of descending virulence indicated by the number of seedlings surviving in this 
experiment. The results from the use of the same strains in experiment No. 72 are 
Shown by the broken line. The obvious correlation between the two curves (coefficient 
0.81+0.04) indicates a real difference in virulence between the different strains. The 
strains indicated by the underscored numbers are original strains and those not under- 
scored reisolations from the original strains in earlier inoculation experiments on pine 
seedlings. 


In the work on pine seedlings, with the possible exception of 
strains 230 and 233, there was no evidence of attenuation in arti- 
ficial culture. Strains 147 and 213, isolated in 1910 and 1911, re- 
spectively, seemed as strongly parasitic in experiments 71 and 72 
(1917 and 1918) as any of the five strains isolated in 1916 or the six 
strains isolated in 1915. : 

Of the 20 strains above mentioned, three pairs were isolated under 
such conditions and showed such later agreement in performance as to 
indicate their individual identity. For the purposes of considera- 
tion in the following paragraph, the one of these probably duplicate 
strains which happens to have the higher number was eliminated from 
each pair. The survival figures in pots inoculated with the 17 strains 


32 BULLETIN 934, U. S. DEPARTMENT OF AGRICULTURE. 


remaining, giving the mean of the results in experiments 71 and 72, 
are shown graphically in figure 13, together with the results of some — 
of Peltier’s experiments in which other strains were used. Per- 
centages of seedlings damped-off after germination are not included 
in these and most of the other data on pines because the most viru- 
lent strains often entirely prevent germination, and no value for sub- 
sequent loss is obtainable. The grouping of most of the writer’s 
strains at the least virulent end of the register (that is, the one with 
the highest number of living seedlings) is of some interest. The 
distributions based on the two experiments considered separately 


- 


3 
© 


tt 

Sabees 

Si : 
gt |= . 
6-N7 

wis 

G4} 86 

NaS 

Wy |< 

GL 5 


STATION 1 © @ @ S 6 7 89 I0 W le 138 «14% 15 +16 %I7 


Tig. 12.—Diagram showing the relation between damping-off of conifers (broken line) 
and soil acidity (solid line). The acidity of soil samples from the different nurseries, 
determined by Dr. L. J. Gillespie, is reported as Pu7, indicating approximate neutrality 
while Pu6 indicates ten, and Psd one hundred times as great a hydrogen-ion concentra- 
tion as Pu7; therefore the lower the hydrogen-ion exponent line, the greater the acidity. 
The seriousness of damping-off at each nursery is on an arbitrary scale in which nurseries 
with negligible loss are rated as 1, and the nursery which suffered most is rated as 10. 
These values are estimates, though for some of the nurseries extensive counts were 
available on which the estimates were based. 


agreed very well in this grouping. The minor group at the end of 
extreme virulence is not taken to indicate an actual grouping but, 
rather, an artificial one, due to the fact that both the strongest 
strains and some less strong were thrown into the same group by 
the lack of additional seedlings for the stronger strains to kill. This 
lack of additional seedlings constituted a limiting factor. In other 
words, conditions favored damping-off even in these two experiments 
too much to permit completely differential results for the more viru- 
lent strains. Despite this artificial limit preventing the full vari- | 
ability becoming evident, the coefficient of variability of the survivals 


DAMPING-OFF IN FOREST NURSERIES. 80 


had the high value of 63-++9.7 per cent. The graph indicates also a 
decided, though less extreme, degree of variability for Peltier’s 
strains on carnations; the survivals for the 18 strains which he used 
in both of his experiments on cuttings have a variability coefficient 
of 29+3.5 per cent and the 23 strains in experiment 2 on seedlings 
55+6.9 per cent. 


al A HIUM DEBARYANG/T 
uivigesheeSe Soneed sey 


CORTICIUM LAGUM 
WPITEPPES STRAINS ON PINE 


oO 
00 00 a ooo 


5 PELTIEPRIS STRAINS ON CARNATION CUTTINGS 


Oo O 
ooo Pei. EO: oO. oO 


PELTIER’S STRAINS ON CARNATION SEEDLINGS 


O QO 
ane CO fy. 1), .| EI C)., £3 
ey aoe se oO Bo oO oe Oo 


O20 40 60 80  /00 
PLANTS SURVIVING PEP 10QIN CONTROLS 


Fic. 18.—Diagram showing the results of inoculations with 17 strains of Corticium vagum 
and 35 strains of Pythium debaryanum, arranged in decreasing order of virulence from 
left to right, as indicated by the survivals in pots of pine seedlings artificially inoculated 
with them. The Pythium results represent the mean survivals in 5 pots inoculated with 
each strain in each of experiments Nos. 66, 67, and 68. Each point located is therefore 
Based on the results in 15 pots, 10 of Pinus banksiana and 5 of P. resinosa. The 
Corticium results on pine represent 5 or 6 pots each, in two experiments (Nos. 71 and 72) 
on P. resinosa. The outline circles represent P. debaryanum strains from Hast Tawas, 
Mich.; the solid circles represent strains from other localities. The second row of 
squares shows the sum of the results in Peltier’s experiments Nos. 1 and la (99, his 
table 3). The lowest row of squares shows his results in experiment No. 2 (his 
table 4). 


The strains represented in figure 13, as used on pine, include 1 
from bean, 2 from potato, 1 from sugar beet, 1 from Elaeagnus, 2 
from Picea engelmanni, and 10 from Pinus resinosa, P. ponderosa, 
and P. banksiana. Two were from Washington, D. C., 2 from New 
York, 1 from Ohio, 4 from Michigan, 4 from Minnesota, 1 from Ne- 
braska, 2 from Kansas, and 1 from California. The sources of these 
strains are widely distributed both as to host and locality; they are 

19651°—Bull. 984—21 3 


34 BULLETIN 934, U. S. DEPARTMENT OF AGRICULTURE. 


rather more representative of the country as a whole geographically 
than the strains in the larger of Peltier’s experiments, though less 
representative as to host sources. The number is too small to justify 
conclusions as to the proportion of Corticiwm vagum strains which 
can be expected to prove strongly virulent on pine. The data are 
offered merely as a beginning, to which it is hoped experimenters 
with other strains of C. vagum will make additions. 

In addition to the strains used in these two experiments, several 
others which had been lost or for other reasons could not be included 
in both the final experiments had been previously tested on pines in 
earlier experiments. Of these, 6 strains, 1 each from alfalfa, sugar 
beet, Pseudotsuga taxifolia, Pinus banksiana, P. resinosa, and P. 
strobus, gave indications of low virulence on the pines; 3 strains, 1 
each from sugar beet, Pinus sylvestris, and P. ponderosa, gave indi- 
cations of rather high virulence; while another strain from P. ponde- 
rosa indicated an intermediate ability to attack pine. Combining 
these strains with those represented in figure 13, there are data on 27 
original strains, of which 8 are roughly classed as strongly virulent 
on pine seedlings, 14 as weak, and 5 as intermediate. 

Edson and Shapovalov (40) have conducted inoculation experi- 
ments on potato stems with 6 of the Corticium strains which had 
been used on pine, including the 5 strains mentioned by them on page 
218 and their strains R. XV (the writer’s strain 192 of fig. 2) on page 
215. Strains 147 and 724, which had proved the most destructive 
in the inoculations on pine, appeared also rather strongly virulent on 
potato. Strain No. 186, originally from potato, which had given no 
definite evidence of parasitism on pine, also proved unable to cause 
lesions on the potato stems. The remaining 3 strains,-all of inter- 
mediate virulence on pine, gave results on potato which were less in- 
dicative of agreement with the order of virulence on pine. The data 
suggest that strains strongly parasitic on potato are likely to be 
strongly parasitic on pine, and vice versa, but the agreement between 
their results and the writer’s is not sufficiently complete to establish 


the point. 
FUSARIUM SPP. 


Fusarium is often found on or in damped-off seedlings (24, 46, 60, 
94, 120, 187, 141, 142). The early inoculation experiments, conducted 
in the main with strains not sufficiently described to allow their iden- 
tification, have been recently summarized (68, p. 537), together with 
descriptions of inoculation experiments on pine seedlings with four 
commonly recognized species of Fusarium. These, though not fol- 
lowed by reisolation, gave rather definite evidence that Fusariwm 
moniliforme Sheldon was decidedly parasitic and F. solani less 
strongly so. Fusarium ventricosum Appel and Wollenw. was indi- - 


DAMPING-OFF IN FOREST NURSERIES. 35 


cated as more strongly parasitic than /’. solani, but in a single test 
only and with a culture of doubtful purity. Pusariwm acuminatum 
KE. and E. gave no evidence of parasitism. These results agreed with 
those of Spaulding (137) in indicating that the ability to attack 
seedling conifers is not limited to a single species of Fusarium and 
that 7. moniliforme is one of the more virulent. The statement by 
Hartig (61, p. 147-150) that a Fusariumlike fungus was able to cor- 
rode the young epidermis of pine seedlings has already been men- 
tioned. 
PYTHIUM DEBARYANUM. 

Pythium debaryanum Hesse (Artotrogus debaryanum Atkinson, 
Lucidium pythioides Lohde) has been known since 1874 (74, 86) as 
a common cause of damping-off of various angiosperms. The first 
known observation was made by De Bary about 1864 (74). Despite 
the large number of hosts on which it has been listed, its parasitism 
has been definitely established on few. Peters (100) has successfully 
inoculated sugar beets with pure cultures; at least part of his strains, 
including presumably part or all of those he used in inoculation tests, 
were obtained from single spores. Edson (38) working with the 
same host, reisolated the fungus from inoculated seedlings, and made 
reinoculations with it. Both find it able to cause root sickness of 
plants not attacked early enough to be killed outright. Johnson 
(82) and Knechtel (85) have caused damping-off of tobacco seed- 
lings with it, and the former reported it also able to persist in the 
cortex and kill the lower leaves of tobacco plants which survived 
attack. The fungus has long been reputed parasitic on potato tubers 
and has now been found by Hawkins (70) to be the chief cause of 
the rot known as “leak” in California. Peters (99) made success- 
ful inoculations with pure cultures on cuttings of Pelargonium. 
Most of the reports of parasitism, however, have been based on 
microscopic examination or more or less crude inoculation expert- 
ments. Noteworthy among the latter are those reported by Hesse 
(74) on Camelina sativa in the original description of the fungus. 
These were made before pure-culture technique had come into use 
with fungi, but were so thoroughly checked by microscopic obser- 
vations at every step in the process that they must be admitted as 
very good evidence of the parasitism of the fungus. A number of 
reported angiospermous hosts are listed by Butler (23), Voglino 
(143), and Johnson (82, p. 34, footnote, and p. 35). Reinking (107) 
recently reported Canica papaya as attacked. A host which the 
writer has not found in the literature is rice, found by Dr. Haven 
Metcalf seriously attacked in the seedling stage in a field in South 
Carolina. A second apparently new host for the fungus is fenu- 
ereek (Trigonella foenum-graecum). The writer found oospores 
typical of Pythium debaryanum in the tissues of damped-off seed- 


36 BULLETIN 934, U. S. DEPARTMENT OF AGRICULTURE. 


lings received by Prof. William T. Horne, from Sonoma County, — 
Calif., with the statement that the disease was seriously affecting 


the stand. The fungus was easily isolated, and the results of suc- 


cessful inoculations on pine with the cultures obtained are included ~ 


in Table V (p. 47). A fungus resembling P. debaryanum was 
also found in damped-off cowpea (Vigna sp.) seedlings grown in 
rotation with pines at a Nebraska nursery. 

Pythium equisett Sadebeck, reported as parastic on the prothallia 
of H'quisetum arvense, was successfully used by Sadebeck (117) in 
crude cross-inoculations direct from /. arvense to potato tubers. 
De Bary (5) reversed the direction of the experiment between 
cryptogamous and phanerogamous hosts by successfully inoculating 
prothallia of /'quisetum arvense with Pythium debaryanum directly 
from diseased Lepidium seedlings. He also secured positive results 
on prothallia of the fern Z’odea africana by the same method. The 
Equisetum prothallia he found to be especially favorable media on 
which to develop Pythium debaryanum. Fischer considers the 
fungus found by Bruchmann (17) and Goebel (49) on prothallia of 
Lycopodium sp. as probably identical with P. debaryanum. A care- 
ful reading of the original articles is sufficient to show that the sym- 
‘biotic fungus which they described was an entirely different or- 
ganism. Saprolegnia schachtui and Sporodospora jungermanniae, re- 
ported on two of the Hepatice, are of doubtful position (42, p. 403), 


though Butler (23, p. 89), after a survey of the literature, apparently © 


favors the view that the former is distinct from the damping-off 
fungus. De Bary (5) reported Vaucheria and Spirogyra apparently 
immune against P. debaryanum. 

Karly fotarcttes to Pythium debaryanum in connection with 
gynosperms seem to have been based on the probability that it 
would be found to be the cause of damping-off in conifers (6; 97; 134, 
p. 27). The first actual finding of the fungus in any gymnosperms 
of which the writer is aware is indicated by a label marked Pythium 
debaryanum in the handwriting of Mrs. Flora W. Patterson on a 
package of coniferous seedlings from a New York nursery collected 
in 1904. The seedlings, judging from the several rather long cotyle- 
dons and the fact that both cotyledons and primary leaves are denticu- 
late, are probably of one of the species of Pinus having medium-sized 
seed. In 1908 Dr. R. J. Pool, of the University of Nebraska, and his 


student, Mr. H. S. Stevenson, obtained in culture from damped-off 


coniferous seedlings a nonseptate fungus which was _ probably 
Pythium debaryanum, but which formed no distinctive spores .on the 


media on which it was grown. A year later the writer obtained the | 


fungus from pine seedlings at the same nursery and reported it as 


4In the Office of Pathological Collections, United States Bureau of Plant Industry. 


—- | ee ee 


le ail 


¢ al te 


DAMPING-OFF IN FOREST NURSERIES. On 


parasitic on pines in preliminary inoculation experiments (62). In 
1910 Spaulding (137) found it on spruce in New York, and Hof- 
mann (76) later made successful inoculations on both pine and spruce 
seedlings, using P. debaryanum cultures both from aerial. trap plates 
and from recently damped-off seedlings of cabbage, radish, and 
Russian thistle (Salsola tragus). Hofmann’s work, detailed notes of 
which the writer has been permitted to examine, was done with cul- 
tures which were contaminated by molds, but was checked up by 
microscopic examination of the lesions resulting, which showed the 
affected tissues filled with nonseptate hyphe. His results are taken as 
a rather strong indication that P. debaryanum attacks spruce as well 
as pine and that the fungus attacking conifers is physiologically as 
well as morphologically identical with that causing the damping-off 
of angiosperms. 

There thus appears from the literature to be reason to believe that 

Pythium debaryanum is parasitic on representatives of two groups 
of the Pteridophyta and on gymnosperms, as well as on various 
monocotyledons and dicotyledons, a range of hosts not only remark- 
able but perhaps unequaled in our present knowledge of plant 
parasites. Final published proof of parasitism seems to be available 
for three or four species of dicotyledons only. Additional inocula- 
tions on conifers with strains isolated from various other hosts are 
reported in the present bulletin. Some of the detailed evidence neces- 
sary for complete proof of the parasitism of the Pythium on conifers, 
lacking in experiments previously reported because of the doubtful 
purity of the cultures used and failure to reisolate and reinoculate 
with the organism, is also given here, together with evidence of the 
ability of the parasite to cause root sickness of pines too old to suffer 
from damping-off. 
_ Descriptive data of interest on Pythium debaryanum have been 
supplied by Hesse (74), De Bary (5), Ward (144), Miyake (89), 
Butler (23), and Butler and Kulkarni (24). An important contri- 
bution to the physiology of the fungus and the factors controlling its 
passage through the tissues of one of its hosts has recently been made 
in the previously mentioned paper of Hawkins and Harvey (71). 


IDENTITY AND ISOLATION. 


The fungus in the writer’s cultures referred to Pythium debary- 
anum Hesse has been so called for the following reasons: 


(1) The morphological characters agree with those described and figured for 
Pythium debaryanum by other workers and with those of strains obtained from 
Dr. H. A. Edson under this name. 

(2) The absence of zoospores in the writer’s cultures agrees with the experi- 
ence of others with Pythium debaryanum (2, 5, 28, 24, 38, 100), all workers 
with pure cultures having obtained zoospores infrequently, if at all. The 
earliest work by Hesse (74) in which zoospores were apparently produced 


38 BULLETIN 934, U. S. DEPARTMENT OF AGRICULTURE. 


readily at certain times of the year was done before the development of pure- 
culture methods. Water cultures kept in the dark and in the light, at constant 
and at varying temperatures, with nutrient substrata consisting of steamed — 
or outoclaved fragments of potato, carrot, Sweet potato, turnip, sugar beet, corn 
meal or rice, nutrient agar, sugar-beet seedlings, and insects have all produced 
only sexual fruiting bodies and chlamydospores (the so-called conidia). 

(8) The successful cross-inoculations, those which Edson (38) used on sugar- 
beet strains and the writer had found parasitic on pine and had used on pine, 
strains which Hawkins had found parasitic on potato tubers and Edson on 
sugar beets, confirm the work of Hofmann (77) in indicating that the Pythium 
which causes the damping-off pine is a parasite on entirely unrelated species 
of host plants, a commonly recognized characteristic of Pythium debaryanum. 


The organism is easily isolated from recently damped-off conifer- 
ous seedlings or from soil direct by placing the seedlings or a lump ~ 
of soil at the edge of a Petri dish of solidified prune agar and transfer- 
ring to tubes mycelium from the advancing edge of the resulting 
growth. It has been found in or obtained from damped-off conifers in 
California, Kansas, Nebraska, Minnesota, and the District of Columbia, 
as well as in cultures made by Mr. Glenn G. Hahnin Michigan. Picea 
engelmannt, P. sitchensis, Tsuga mertensiana, Pinus nigra austriaca, 
and Pseudotsuga taxifolia are the coniferous hosts from which cul- 

tures of Pythium debaryanum have been obtained. It has been iso- 
lated directly from soil not only in coniferous seed beds but from 
open grassland in California not adjacent to any seed bed or culti- 
vated crop. Unless Mucor is abundant, Pythium is commonly ob- 
tained in apparently pure condition on the first transfer from the 
plate, as prune agar appears unfavorable for most bacterial growth 
while allowing rapid spread of the Pythium. On media made from 
prunes which taste sweet and with a total gross weight of not more 
than 40 or 50 grams per liter of medium, the Pythium will make a 
rapid growth, often extending radially 1 mm. per hour at tempera- 
tures in the neighborhood of 22° C. and produce both chlamydospores 
and oospores. <A less valuable medium for isolation work, but more 
convenient for subcultures than any other which has been tested, is 
autoclaved corn-meal agar. The growth is not luxuriant, but spores 
are always formed and the cultures seem to be as long lived as those 
on any other medium, retransfer being rarely necessary more often. 
than twice a year. Much stronger growth and more abundant fruit- 
ing is obtained on such media as sugar-beet or rice-stem agar, but 
the leathery surface of the culture on such media makes transferring 
dificult. On rice grains, corn-meal mush, beef agar, and on corn- 
meal agar plus 2 per cent dextose or sucrose no spores are formed 
and the cultures are short lived, though growth is heavy and on 
the last-named medium extremely rapid. On agar containing the 
juice from sour prunes or on corn-meal agar prepared without sub- 
jecting it to the high temperature of the autoclave, both growth and 
fruiting have been very poor or even lacking. 


-DAMPING-OFF IN FOREST NURSERIES. 39 


In both artificial cultures and in the tissues of coniferous and 
dicotyledonous hosts the numerous strains observed showed no con- 
spicuous differences in the size or other characters of the spores pro- 
duced, though noticeable and constant abnormality was found in one 
strain in the readiness with which spores were produced and in two 
strains in the ratio between chlamydospores and oospores in agar 
cultures. In the first-mentioned strain, obtained from pine in 
Kansas, and in cultures reisolated from seedlings inoculated with it, 
both chlamydospores and oospores are produced tardily and so 
scantily that it is often difficult to find them. In most strains, on 
the other hand, almost the entire contents of the mycelium are 
promptly emptied into the spores as soon as the limits of rapid vege- 
tative growth are reached. In another abnormal strain from pine 
from the same locality, and in still another furnished by Hawkins 
from a California potato, chlamydospores are produced in large 
numbers, but oospores are few. In many other strains, including 
several from California, the opposite condition obtains, oospores in 
plate cultures being decidedly more numerous than chlamydospores. 
These peculiarities of particular strains seem to be fairly constant 
characters, the first abnormal strain mentioned having been under 
observation for more than three years without any change in its tend- 
ency to scanty fruiting, and the low ratio of oospores to chlamydo- 
spores having been constant during the shorter periods over which 
the observation of the other strains extended. In view of the small 
variation between different strains in the matter of speed of growth, 
a purely vegetative character, this variation in reproductive habit 
is Somewhat surprising. ‘The strain which produced spores infre- 
quently was unquestionably parasitic, though it killed fewer seed- 
lings than the average Pythiwm debaryanum strains. The strains 
with the high ratio of chlamydospores were both of at least average 
virulence on pine. | 

Oospores in the strains the writer has had in culture, whether ex- 
amined in agar, in water cultures, or in root tissues, have ordinarily 
been somewhat larger than the diameter of 14 or 15 to 18 » given in 
a number of the descriptions. The maximum range has been 12.8 
to 20.6 u, the same strain sometimes being well down within the usual 
size range and sometimes ranging from 17 to 20 yp. The largest 
oogones observed were 26 » in diameter. Various stages of fertili- 
zation are shown in Plate I, figures 2 to 4. Chlamydospores attain 
a maximum diameter in the case of the limoniform intercalary forms 
of 32 w, and spherical chlamydospores sometimes reach a diameter 
of 28. There is no lower limit for these bodies, as under unfavor- 
able conditions—e. g., in sour-prune agar—they are sometimes all less 
than 15 p in diameter, and the smaller ones are little larger than the 


40 BULLETIN 934, U. S. DEPARTMENT OF AGRICULTURE. 


hyphe which bear them. Both oogones and chlamydospores may be _ 
either terminal or intercalary. 

The normal hyphe are large, varying from 3 to 7 » and sometimes 
more in diameter. Typical hyphx, showing the false septa developed — 
at the boundary of the protoplasm and the portions of the hyphe ~ 
which have been evacuated in the extension of the younger parts, are 
shown in Plate I, figure 1. At points at which the ends of hyphe come 
in contact with the glass of the culture dish, peculiar contact swell- 
ings are produced (PI. I, figs. 5 to 7), much the shape and size of 
antheridia, but not walled off from the adjacent hyphe and having 
no apparent significance in the life history of the fungus. These are 
not always terminal (PI-d, fig. 8). It is noteworthy that Hesse de- 
scribed contact swellings at the tips of the hyphe just before pene- 
trating the epidermis of Camelina sativa. 

The asexual nonsporangial fruiting bodies of Pythium debaryanum 
are referred to as chlamydospores rather than as conidia, though in 
most of the previous literature the latter term has been used for 
them. Hesse called the terminal bodies conidia and the intercalary, 
gemme (74). It is believed that the best terminology and the one 
which should be followed for all fungi, as it now is for most, is that 
which limits the term conidium to a spore which is adapted primarily 
for aerial distribution or which is at least readily separated as soon 
as it is mature from the parent hypha from which it arises. The 
most typical conidium, in fact, is a spore which is abstricted by the 
parent hypha at maturity. The asexual spores of this Pythium re- 
main attached to the parent hyphe indefinitely even after the hyphe 
are dead and empty. It is a common thing to find numbers of these 
bodies in -water cultures, still attached to hyphze which are so com- 
pletely empty that it is only with favorable lighting that their thin 
colorless walls can be seen. So firm is the attachment that vigorous 
shaking is required to release any considerable proportion of the 
spores. It seems probable that in nature the spores are released 
chiefly as a result of the destruction of the hyphee walls by bacteria. 
While there is reason to think that Pythiuwm debaryanum is some- 
times disseminated by wind, it is by no means certain that it is 
through the medium of these spores. It is true that these bodies have 
thinner walls than are commonly found in chlamydospores of some 
other fungi, but they have somewhat thickened walls as compared 
with the vegetative hyphe, and they are commonly intercalary. 
These facts, and the indications that they are better able to with- 
stand unfavorable conditions than are the hyphe, all tend to entitle 
them to rank as chlamydospores. De Bary (5) speaks of them as 
“ dauerconidia.” Their ability to stand drying is not entirely demon- 
strated, but is indicated by the relative longevity of the fungus on 
different media. On beef agar and on rice, on which no spores are 


Bul, 934, U. S. Dept. of Agriculture. PLATE | 


PYTHIUM DEBARYANUM FROM ARTIFICIAL CULTURES. 


Fic. 1.—Hyphe, showing old portions of hyphe and false septa separating them from the portions still 
containing protoplasm. Fieas.2 to 4.—Various stages of oospore formation. Fias. 5 to 8.—Hyphal 
swellings at points of contact with glass. From camera-lucida drawings. 


A 


DAMPING-OFF IN FOREST NURSERIES. 41 


formed, a few tests indicate that the fungus is very short lived, 
sometimes dying in a month. On media on which spores are pro- 
duced, transfers any time before the sixth month, and often as late 
as the tenth month, start immediate growth on fresh media. This 
is true even for strains which produce few or no oospores. The im- 
mediate commencement of growth from cultures 3 or 4 months old 
is taken as an indication that the new growth results from the 
asexual spores, as oospores are commonly believed to require a rest- 
ing period of five or more months, before they are able to ger- 
minate (5, 38). 
INOCULATION ON STERILIZED SOIL. 

Pythium debaryanum has been used in inoculation in pots of 
recently autoclaved soil in 16 different series of tests. In 10 of these, 
fragments of agar cultures were scattered over about one-fourth 
of the area at the side of each pot when seed was sown; in 2 of these 
10 and also in 2 other tests some pots were inoculated over their 
entire surface. In every one of these 12 heavily inoculated series 
positive results were indicated by smaller emergence and where any 
considerable number of sprouting seeds escaped the fungus by heavier 
damping-off loss in the inoculated pots than in the controls. In 
some cases the fungus killed all or practically all of the seed or 
seedlings in the inoculated pots before they emerged from the soil. 

In a total of 7 series, part or all of the pots received lighter in- 
oculations, consisting of one or two small fragments of an agar 
culture placed just below the surface of the soil at the edge of each 
pot. In 5 of these success was indicated. In the sixth and seventh 
also of these hghtly inoculated sets, there was more damping-off in 
the inoculated pots than in the controls, but the difference was neg- 
hgible. The damping-off caused by light inoculations was in general 
distinctly less than that resulting from broadcast inoculations. To 
sum up the evidence: Sixteen separate experiments were conducted 
with Pythiwm debaryanum on pine seedlings in autoclaved soil, and 
in every one fewer seedlings survived in the inoculated pots than in - 
the checks; the difference in most of the experiments was large. 

Of the successful inoculation experiments—that is, those in which 
the difference between the inoculated pots and the checks seemed 
significant—9 series included jack pine (Pinus banksiana), T series 
western yellow pine (P. ponderosa, Colorado and New Mexico seed), 
and 3 series red pine (P. restnosa). In addition to the pines, Doug- 
las fir (Pseudotsuga taxifolia, Colorado seed) was grown in two large 
plats in one of the earlier series, one being inoculated over its entire 
surface with Pythiwm debaryanum. Because of the poor quality 
of the seed in the test on Douglas fir, too few seedlings were obtained 
to furnish a decisive test, but the difference in the emergence in the 
inoculated plat and the control affords preliminary evidence that 


42 BULLETIN 934, U. S. DEPARTMENT OF AGRICULTURE. 


Pythium can cause the “ germination-loss” type of damping-off in 


Douglas fir as well as in species of Pinus. Of the seeds sown in the 
control plat 43 produced seedlings which appeared above the soil, 
while only two seedlings appeared from an equal number of seeds 
sown in the inoculated plat. | 
Altogether, 38 strains, excluding reisolations, have been tested on 


one or more of the 3 pine species. Strains from both the Pacific 


coast and the eastern United States and from a number of hosts 
other than pines were among those used. With the exception of two 
or three strains from a pine nursery in Michigan, the use of which 
was followed by so little damping-off as to leave their parasitism 
uncertain, all of the strains proved parasitic under favorable condi- 
tions, though some were more virulent than others. The positive re- 
sults in the 14 successful experiments are based on the comparison 
of a total of approximately 1,160 inoculated pots with 195 control 
pots. : 


TABLE III.—IJnoculation experiments with, Pythium debaryanum in pots of steri- 
lized soil. 


Pythium strain. Results. 
Num- Damp- id 
_ Series, experiment number, ber | Inoculation ing-off | Sur- 
and host. Initial strain of method. Emerged| after | vival 
No. from which it | pots. (per 5-pot| germi- | (per 5- 
wasreisolated. unit). |nation| pot 
(per | unit). 
cent). 
SERIES A.—Initial inocula- 
tions: 
VA 5. a eee eke. eee 5 | Agarcultures|  . 1 100 0 
_ broadcast 
No. 58, Pinus banksiana. . - ais 
Controls, Pac 2 ee. ee 5 |Noinoculum 74 0 74 
AG (0 Nees lee, Se aes ee a eS n|=..Se dol Sars 82 0 82 
2952 5222 SRR Aaa ee cae Se 5 | Agarcultures 41 28 30 
at single 
No. 58, Pinus ponderosa.. point in 
each pot. 
Controls. | 325-2 see eee 5 | Noinoculum 55 0 55 
715) ee | Cee eS ee a Be 5 | Agarcultures 16 81 3 
broadcast 
at one side 
of pot. 
ELMOL Seah ee ca citea ie its | ean eles Ol52. ke 18 89 2 
Controls) 23826 eee 5 | Noinoculum 90 0 90 
2:00. alba note See eae eee doicsce ze 82 0 82 
No«62Pinus banksiana: .|)- G0>.¢ sal eee ee eee eee (yl eee do: A322 82 0 82 
BOsasss. |: Petes a sekcenae 5 | Agarcultures 14 72 4 
broadcast | | 
at one side 
of pot. 
SATE SONEARSe o's a ee ole ON eee dor. lai 3 67 1 
SAS. 2d] ee arene acre (5) a doo ee 13 67 4 
Controle ij. Bea i2 5 | Noinoculum 78 0 78 
Series B.—Reisolatedstrains: 
S083. ae. No. 295 (in P. 5 (b) 14 72 4 
No. 62, Pinus banksiana. . te ee 
Controls!|_ 220 setae see oe Dilan Mee eet ee 78 0 78 


aA different soil used in these pots from that used with strain 258 and the first, three control units. _ 

bAllinoculations with fragments of agar cultures scattered broadcast at one side of the pot, including 
about one-fourth ofits area. Nothing was added to the controls in experiment 62, but sterile agar was 
added to the controls in experiments 66, 67, and 68. 


{ 


DAMPING-OFF IN FOREST NURSERIES. 43 


TABLE III.—IJnoculation experiments with Pythium debaryanum in pots of steri- 
lized soil—Continued. 


Pythium strain. Results. 
Damp-| 
° ° . = ur- 
Serjes, experiment number, Initialstrain ber Pnopma ti Emerged Phen rive 
and host. No. from which it 1 geen h |(per 5-pot| germi- | (per 5- 
was reisolated. | P°'S- unit). |nation| pot 
(per | unit). 
cent). 
Series B.— Reisolated strains— 
Continued. 
(8882... 2 No. 295 (in P. 5 (2) 9 67 3 
ponderosa, 
expt. 58). 
B45e ot ore No. 218 (in P. 5 (a) 15 33 10 
banksiana, 
expt. 58). ° 
ANAM os 2 No. 258 (in P. 5 (a) 36 25 27 
banksiana 
No. 66, Pinus banksiana. . expt. 62, 2d 
unit). 
Ase eee do... es 5 (a) 59 10 54 
BNO eT oleh No. 348 (in P. 5 (a) 25 100 0 
banksiana, 
expt. 62). 
AMD <2 0s No. 347 (in P. 5 (a) 41 72 11 
‘ banksiana, 
expt. 62). 
Gorninols,|'; 75. eee D1) Se ne gee 75 14 64 
BSeee No. 295 (in P. 5 (a) 7 57 3 
ponderosa, 
expt. 58). 
3): 5 a No. 218 (in P. 5 (a) 24 37 15 
‘ banksiana, 
expt. 58). 
AMAT dL: No. 258 (in P. 5 (a) 57 24 44 
banksiana, | 
‘expt: 62, 2d 
| unit). 
No. 67, Pinus banksiana..(415...-... No. 258 (in P. 5 (a) 30 37 19 
; | banksiana, 
expt. 62, 1st 
unit). 
ANGE. 3. No. 348 (in P. 5 (a) 62 65 22 
banksiana, 
expt. 62). 
ASO S..235. No. 347 (in P. 5 (a) 53 27 39 
banksiana, 
expt. 62). 
Wontrols |... == \eegeee ects 23: |e eee <5 87 5 83 
Seis aan No. 295 (in P. 5 (a) 85 26 63 
_ ponderosa, 
expt. 58). - 
Stole. | No. 218 (in P. 5 (a) 76 24 58 
banksiana, 
; expt. 58). 
AA ee wins No. 258 (in P. 5 (2) 98 14 84 
banksiana, 
expt. 62, 2d 
unit). 
No. 68, Pinus resinosa. ...|{415...... No. 258 (in P. 5 (a) 92 11 82 
banksiana, 
expt. 62, 1st 
unit). 
ANOS sai No. 348 (in P. 5 (a) 95 45 52 
banksiana, 
> expt. 62). 
45055545. No. 347 (in P. 5 (a) 84 40 51 
banksiana, 
expt. 62). 
G@ontnols: |e =<: - ceeeene SE | eine sbreer ss ote 104 0 104 


@ Allinoculations with fragments of agar cultures scattered broadcast at one side of the pot, including 
about one-fourth of its area. Nothing was added to the controls in experiment 62, but sterile agar was 
added to the controls in experiments 66, 67, and 68. 


As has been stated, securing positive results did not always mean 
that the control pots remain uninfected. Even with the most care- 


* ful treatment and the use of boiled water throughout the experiment 


44 BULLETIN 934, U. S. DEPARTMENT OF AGRICULTURE. 


it proved difficult to keep the control pots entirely free from damp- 
ing-off, Cultures from seedlings which damped-off spontaneously 
in control pots indicated that Pythium as well as Fusarium may be 
introduced by accident, even when insects, birds, and rodents are ex- 


cluded. This agrees with the evidence of Hofmann (77) that: | 


Pythium debaryanum is sometimes disseminated by wind, despite 


its apparent lack of adaptation to wind distribution. It is also in-— 


dicated, however, that unheated tap water increases damping-off 
when used on control pots and probably carries this semiaquatic 
fungus. Notwithstanding infections in the controls of amumber of 
the experiments, it is believed that the large number of pots whose 
results have been considered in drawing conclusions, the fact that the 
Pythium pots lost more heavily than the controls in every one of the 
16 experiments, and the magnitude of the differences between both the 
emergence and subsequent damping-off figures for the inoculated pots 
and the controls in most of the experiments establish the parasitism 
of the fungus in inoculation on autoclaved soil without it being neces- 
sary to present all the evidence in detail. The pot series which in- 
volved reisolation and reinoculation (Table III), together with the 
results given for other purposes in Tables V and VI, seem sufficient 
by themselves to establish a parasitic relationship. 


REISOLATION AND REINOCULATION. 


In a number of the experiments dead seedlings in the inoculated 


pots were examined and typical Pythium hyphe and spores were 
found. In three of the experiments in which the controls remained 
entirely free from disease up to the time the experiment was closed, 
reisolations and reinoculations were made in accordance with the 
usual rules of proof. The results are given in Table III. 

From Table III it will be seen that five strains reisolated from 
Pinus banksiana and one strain reisolated from P. ponderosa gave 
positive results in pots of P. banksiana and P. resinosa. In addition 
to the reinoculations shown in the table, the strain reisolated from 
Pinus ponderosa (No. 338) was again reisolated in duplicate from 
P. banksiana in experiment 62, and both these secondary reisolations 
gave cultures which were parasitic on P. banksiana and P. resinosa 
in subsequent inoculations. 

That the organisms reisolated were actually the same as those used 
in the initial inoculation is indicated not only by the absence of dis- 
ease in the control pots of experiments 58 and 62, but by the distinc- 
tive characters of some of the strains. In general, cultures reisolated 
from strongly parasitic initial strains were themselves strongly 
parasitic and vice versa. This is shown by comparing the figures for 
the initial and reisolated strains, as shown in Table IV. Each figure 
represents the average results in 10 pots of jack pine and 5 of red 


ag 


DAMPING-OFF IN FOREST NURSERIES. 45 


‘pine in experiments 66, 67, and 68 combined. The figures are rel- 
ative, the mean survival of 47 different strains used in all three ex- 
periments being taken as 10. A survival figure above 10 therefore 
means that the strain was less destructive than the average Pythium, 
and a figure below 10 indicates more than average virulence. As 
strain 218 was not used in these three experiments, strain 345 can not 
be compared. 


TABLE 1V.—Comparative virulence of original cultures and reisolated strains of 
Pythium debaryanum in experiments 66, 67, and 68. 


Rela- Rela- 
Pythium strain. Description. ate Pythium strain. Description. ane 
vival. vival. 
ING. ZaSeaec 2.2 c= Original culture......... 1Gr iN» 409.2 ae Reisolated from 338. -..- 9 
INO 4B oe oisisis axe 3'e Reisolated from 258... -. 12s Osea. 2k 428: Original culture......... 4 
Ios UG) Soe ee (l0)S ded 282s eee TQ HRINO] 450 sees. aos Reisolated from 347. .... 7 
INIOt 29S ess ce = Origing] culture......... ATW RINO. S48 ace claere e~ Original culture......... 10 
INGOs aSiesce.s «22 = Reisolated from 295. ASIN AIOE oes. cc Reisolated from 348... .. 4 
INOv408... -5---- Reisolated from 338. -.... 6 


These figures are not absolutely consistent, but are to be viewed 
as contributing to the evidence furnished by the absence of damping- 
off in the control of experiments 58 and 62 that the cultures reiso- 
lated in those experiments were actually identical with the original 
strains. A further proof of this identity is in the fruiting tendencies 
of the strains. Both Nos. 414 and 415, the strains reisolated from 
original strain 258, exhibited the peculiarly sparse spore production 
which has been characteristic of strain 258 for the entire period dur- 
ing which it has been in culture. The other reisolated strains, taken 
from pots inoculated with normally fruiting strains, all showed 
normal spore production. 


PURITY OF CULTURES. 


A slight deficiency in the evidence as to the parasitism of Pythium 
debaryanum both in the writer’s work and apparently in all previous 
investigations except those of Peters (100) and possibly Knechtel ° 
is the lack of single-spore cultures. The large number of strains 
which have remained apparently pure through numerous subcultures 
and have retained their individual characteristics as to virulence and 
fruiting tendencies (one strain having been carried on artificial 
media continuously for eight years without material change) give 
very strong justification for believing that the cultures used were 
pure. In three early inoculation tests the cultures used were after- 
wards found to have been contaminated by bacteria carried by mites; 
the positive results obtained in these three were the basis of the ear- 


5 Knechtel’s work in Rumanian has been available to the writer only in the German 
abstract, which makes an ambiguous statement on this point, 


46 BULLETIN 934, U. S. DEPARTMENT OF AGRICULTURE, 


liest report of pathogenicity (62), but have not been used as evidence rr 
in the present bulletin, though the contaminating bacteria in one of 
them, when tested indapieninddse showed no evidence of parasitism. 
In all the experiments mentioned in the foregoing as giving positive — 


results with Pythium the cultures used were apparently pure. 
Cultures from single chlamydospores should be reasonably easy 
to secure, part of the chlamydospores in water cultures being separa- 
ble from the mycelium by vigorous shaking, and further inoculation 
tests with cultures so obtained are probably desirable. The experi- 
ments so far conducted are believed to be sufficiently conclusive, how- 
ever, for all practical purposes. For isolation of absolutely pure 
lines of this or any other ccenocytic fungus, it is evident, as pointed 


out by Dr. W. H. Weston (146), that isolations should be made from. 


the uninucleate swarm spores. For the determination of the bare 
fact of pathogenicity such a refinement would be superfluous. 


© 
CROSS-INOCULATIONS. 


The physiological identity of ‘the Pythium attacking coniferous 
seedlings with the one which attacks dicotyledons is indicated by 
the results of several inoculation experiments. The last two experi- 
ments, one with jack pine and one with red pine for the host, are 
_the most comprehensive and give results sufficiently decisive so that 
quotation of the corroborative evidence from earlier experiments 


is considered unnecessary. The results appear in Table V. Each © 


unit consisted of five 3-inch pots except in the controls, in which 
23 pots were used in the jack-pine experiment and 18 in that with 
red pine. In the second experiment, separate records were kept of 
the survival in each pot, and the probable error calculated from the 
controls was less than two seedlings per pot for a single pot, less 
than 0.9 for a mean of 5 pots, and less than 0.5 for the mean of the 
18 control pots. While the number of controls was, of course, in- 
sufficient to furnish an exact basis for such a calculation, the small 
value found tends to confirm the impression gained from inspection 
of the table that considerable confidence can be placed in the results. 

The difference appearing in Table V between jack pine and red 
pine in point of susceptibility to germination loss from Pythium 
agrees with field observations in Nebraska, the red pine at the Bessey 
Nursery, though on the whole more susceptible than jack pine to 
damping-off losses, having given indication of more resistance to the 
disease for the first week or two. Inoculations in other experiments 
on western yellow pine indicate that the strains which attack it are 
identical with those attacking jack pine and red pine. 

The conclusion reached from the cross-inoculation results is that 
the Pythium causing damping-off of the three species of pine men- 


DAMPING-OFF IN FOREST NURSERIES. 47 


tioned is identical with Pythiwm debaryanum, causing leak of potato 
tubers and the damping-off of seedlings of. two dicotyledonous 
families. 


TABLE V.—Results of imoculations on jack pine and red pine with Pythium 
debaryanum from various hosts. 


Inoculation results. 


On jack pine. On red pine. 
Strain. Host from which isolated. : 
ur- 
Emerged ae vival | Emerged aren uae 
(per 5-pot G s (per |(per 5-pot @ er | (per 
unit). e 5-pot]} unit). Pp Pp 
cent). unit). cent). | pot). 
Dicotyledons: 

No. 131 4 Potato tuber..... eer eer ccc CS || a a 03 30 101 23 | 15.6 
No. 8106 Qe tt see. aise ce eee 45 34 30 62 41 7.4 
Average potato. .........-.-.-- 45 So 30 82 327) 2 ll6 
No. 294 ¢ Sugar-beet seedlings................- 50 8 46 79 36°| © 10,2 

No. 295 ¢ Originally potato strain 131, but 

twice inoculated on and reisolated 

from sugar-beet seedlings by Ed- 
S00 See Sy See A ie Fe 28 32 19 62 48 6.6 
No. 296 d Sugar-beet seedlings.................- 19 32 13 68 58 5.8 
Average, sugar beet........... 32 24 | 26 70 47 7.4 
No. 529 Fenugreek seedlingsd................ em 36 | at 25 102 26"|' 15.0 
No. 530 ID Osnc oo serg Oe a eee oa 60 49 31 108 22 16.8 
“Average, fenugreek...........- 48 40 28 105 24| 16.0 

Conifers: 

No. 258 Western yellow-pine seedlings....... 58 | 9 53 109 17| 18.0 
No. 550 Sitka spruce seedlings.............-. | 15 | go; 3 39 98 2 
No. 555 Engelmann spruce seedlings........- 42 | 29 30 45 70 5. 0 
Average, spruces. .....-..-2..- 29 | 55 17 42 4 | 206 
0 SE 2 | 87 | 5 83 104 0| 20.9 


a Furnished by Mrs. C. R. Tillotson: has been used » Furnished by Dr. L. A. Hawkins: cause of leak. 
successfully on sugar-beet seedlings by Dr. H. A. ¢ Furnished by Dr. H. A. Edson. 
Edson. d Diseased material furnished by Prof. W. T. Horne. 


VARIATIONS IN VIRULENCE OF PYTHIUM STRAINS ON PINE. 


In Pythium debaryanum strains, as in the case of Corticium 
vagum, there appeared to be a considerable difference in the parasitic 
activity of different strains used in the same experiment. Figures 
14, 15, and 16 show graphically the results from inoculations with 
different strains of P. debaryanum in all the experiments in which 
it was possible to compare directly the activity of different strains. 
All the inoculations involved at the time of sowing the addition to 
the soil of cultures on nutrient media in recently autoclaved 3-inch 
pots. In experiment 31C the inoculum fragments were scattered over 
the whole pot, in 31D at only one point in each pot, and in the others 
were distributed over about one-fourth of the pot’s area. As noted 
elsewhere, the variations observed in the results may have been due 
in part to differences in the ability of the different strains to main- 


48 BULLETIN 934, U. S. DEPARTMENT OF AGRICULTURE. 


tain themselves saprophytically in the soil used rather than entirely 


due to difference in virulence. 

The data shown in figures 15 and 16 indicate in the first place 
rather more accidental variations in the results with Pythium than 
with Corticium (see figs. 1, 2,10, and 11). The agreement between 
original and reisolated strains from the same original source is de- 
cidedly less good than in the case of Corticium (see experiments 71 
and 72, figs. 10 and 11). In general, there are only two strains of 


HOST ells BANKSIANA PINUS PESINOSA 
YEAR| /913 1916 
| 0 | 


EXPT. Ss ace [eno | 66 | 67 [es 

2% 

® NSO 

SN 

> 

§ 8 

= S20 

NS 

Ne 


Fie, 14.—Diagram showing variations in virulence as indicated by the living seedlings 
in pots of autoclaved soil inoculated with different strains of Pythiwm debaryanum. For 
experiments Nos. 31 and 66 to 72, inclusive, the surviving seedlings at the end of two 
or three weeks after germination are shown. For the other experiments damping-off 
was so heavy in the inoculated pots that the survivals did not give differential results 
for the different strains, and the germinations are therefore shown. ‘The reports are 
based for experiments Nos. 71 and 72 on 2 or 83 pots for each strain in each experiment, 
and for the other experiments on not less than 5 pots for each strain. In experiments 
Nos. 66, 67, and 68 the number of pots in each experiment for the strains whose 
reisolations were also used varied from 10 to 40 for each strain, the results of the 
separate 5-pot units being shown in figure 15. The strains indicated by the different 
symbols are as follows: From potato: @=Strain 131, isolated in 1909, California, 
Furnished by Mrs. C. R. Tillotson. From sugar beet: O=Strain 295 and its reisola- 
tions from pine. No. 295 was furnished by Dr. H. A. Edson as a reisolation of strain 
131, after having been passed by him through two generations of sugar-beet seedlings. 
A=Strain 294, isolated in 1912. Furnished by Dr. Edson. A=Strain 296, isolated 
in 1912, Wisconsin. Furnished by Dr. Edson. X= Strain 297, originally from pine, 
Nebraska, 1911. Passed through two generations of sugar-beet seedlings by Dr. Edson. 
From pine seedlings: #=—Strain 255, Kansas, 1913. Chlamydospores numerous ; 0ospores 
rare. §§—Strain 258 and its reisolations, Kansas, 1913. A sparsely fruiting strain. 
O =Strain 218 and its reisolation, Kansas, 1912. ©=—Strain 347 and its reisolation, 
Washington, D. C., 1915. -]—Strain 348 and its reisolation, Washington, D. C., 
1915. A=Strain 349, Washington, D. C., 1915. H—Strain 354, Minnesota, 1915. 


Pythium which can be said to have definitely shown difference in 
activity continuing through several years and on different species of 
pine. These are strains 295 and 258. As No. 258, the weak strain, 
has also been found abnormal in its fruiting tendencies, the evidence 
in these graphs does not indicate a decided difference in virulence 
between different typical strains of Pythiwm debaryanum. The 
other strain, which seems rather uniformly weaker than No. 295, is 
No. 181, which according to Dr, Edson’s records was originally the 


ber 


| 


DAMPING-OFF IN FOREST NURSERIES. 49 


same strain, No. 131 having been twice used in his inoculation ex- 
periments on sugar beets and strain 295 recovered from the second 
experiment. The apparent difference between this original strain 
and its supposed reisolation may possibly be due to the treatment 
given strain 131. Before it was used in any of the experiments 
shown but after it had been used by Dr. Edson, it was allowed to 
get very dry and was revived with great difficulty, growth being 
very slow. While it apparently recovered all of its normal growth 
qualities after one or two transfers, it 1s thought that this may 
possibly explain the 
apparently decreased 
virulence in the later 
experiments. 

The failure to se- 
cure as definite indi- 


[Avs BANKSIANA | Fines 


ja17 | 1917 | 
‘L620 | 66 er | e-. | 


a ae 
EE 


- 


cations of constant GX” 
virulence differences SE Ao 
as were obtained for NS 
several of the Cor- Wd Sao 
ticium strains is be- oS 
lieved to be in part 3Q20 
due to a smaller S& 
actual difference be- Nit 0 
tween the different x 


: ° Fig. 15.—Diagram showing the results of inoculations with 
Pythium strains ap- strains of Pythium debaryanum. This figure supplements 
pearinginthe graphs figure 14, giving the results for original and reisolated 
° strains independently. Each point plotted is based on 
and a part to a the results in five pots. The object of this diagram is to 
larger accidental Va- give an idea of the degree of variability in the success of 
ors inoculations. An explanation of the symbols used will 
riation between re- be found in the legend of figure 14. 
sults in pots inocu-- 


lated with the same strain. The growth of Pythium on agar media is 
much more affected by variations in the substratum than is the growth 
of Corticium, and it is rather natural to expect greater variations when 
the two fungi are added to autoclaved soil. In experiments 66, 67, and 
68 a number of strains not used in the earlier experiments were tested, 
in addition to the strains previously used. The survival results for 
all the different strains, both original and reisolated, 47 in all, are 
shown graphically in figure 16. The results in experiments 66 and 
67, both on Pinus banksiana, are averaged and taken as the subject, 
while the results with the same strains in experiment 68 are made 
relative and shown by the broken line. The correlation between the 
performance of the same strains on the two species of pine is by 
no means as clear in the graph as it was in the case of the Cor- 
_ticium strains (fig. 11). The areas bounded by the broken line and 
19651°—Bull. 934214 


50 BULLETIN 934, U. S. DEPARTMENT OF AGRICULTURE. 


the horizontal line showing the location of the mean for experiment 
68 are much larger below the means than above it in the left-hand 
portion of the graph, while the reverse is true in the right-hand 
portion. To this extent the relative activity of the strains in this 
experiment agrees with the performance of the same strains in the 
» two jack-pine experiments, as shown by the solid line. It can not 
be decided from an inspection of the graph whether there is a real 
agreement, in view of the large accidental variation present. How- 
ever, the correlation coefficient, 0.446+0.079, five and one-half times 
its probable error, indicates a considerable correlation, not as good 
as was found for the Corticium strains, but sufficient to establish a 
strong presumption that observed differences in activity of the dif- 


SEZOLINGS SURVIVING PER &-FOT UNIT 


SEDER EEE EEE 


Fig. 16.—Diagram showing the comparative virulence of 47 strains of Pythium achengdataes 
in successive inoculation experiments on species of Pinus. The results in experiments 
Nos. 66 and 67 (on Pinus banksiana) are shown by the solid line, the strains being 
arranged from left to right in the order of descending virulence indicated by the number 
of seedlings surviving in those experiments. The results from the use of the same 


295 


OOO REE ELR RECURSO EUMLET 


STRAINS OF PYTHIVM DEBGARYAN 


strains in experiment No. 68 (on Pinus resinosa) are shown by the broken line. Such — 


correlation as there is between the two curves (coefficient 0.45+0.08) goes to indicate 
a real difference in virulence between the different strains. The strains indicated by 
the underscored numbers are original strains, and those not underscored are reisolations 
from the original strains in earlier inoculation experiments on pine seedlings. 


ferent strains in these inoculation experiments were in part actually 
due to differences in the capacity of the strains. 

It has been suggested in the foregoing that the difficulty in demon- 
strating constancy in the difference in virulence between the various 
strains of Pythiwm debaryanum is due in part to the lack of such 
extreme differences as were observed between the various Corticium 
strains. Figure 13 shows the distribution of the different original 
Pythium strains according to the virulence indicated in the three 
inoculation experiments of figure 16 (application to autoclaved soil 
at the time of sowing). Each value plotted is based on the average 
results in 15 pots. Of the strains used, 21 were from species of pine, 
1 from spruce, 2 from potato tubers, 2 from fenugreek, 3 from sugar 
beet, and 6 from soil direct. Despite the considerable number of 


ee ee oe 


- 
{ 


DAMPING-OFF IN FOREST NURSERIES. 51 


strains, they are not much more representative than the smaller num- 
ber of Corticium strains experimented with. All of the strains from 
soil direct and 11 of the strains from pine were taken at approxi- 
mately the same time from the same nursery in Michigan by Mr. 
Glenn G. Hahn; despite the fact that these were the most recently 
isolated of the strains used, nearly all of them proved weak in the 
inoculations. Of the 17 strains which proved the weakest (out of 
35), all but 3 were from this Michigan nursery. The 18 strains from 
other sources (5 from California, 2 from Minnesota, 2 from Kansas, 
1 from Wisconsin, 2 from an unknown locality, and 6 from Washing- 
ton, D. C., representing two coniferous and three dicotyledonous host 
genera), as shown by solid circles in figure 13, for the most part were 
rather closely grouped within the more virulent portion of the range. 
The coefficient of variability in the survivals allowed by the 35 
Pythium debaryanum strains is 39+3.6 per cent, while for the 
smaller number of original strains of Corticitum vagum in experi- 
ments 71 and 72 it is 63+9.7 per cent. It is evident from figure 13 
that if there had not been a disproportionately larger number of 
strains from the Michigan nursery the variability of the P. de- 
baryanum strains would have been much less than 39 per cent. 
The number of strains was, of course, altogether insufficient for either 
fungus to represent adequately a population as immense as the total 
number of strains of either of these omnipresent species. The above 
data, however, contain the only available information of which the 
writer is aware on variation in the virulence of different strains of 
P. debaryanum. 

The evidence as a whole, both from the results shown in figure 13 
and the experience with 6 other strains which were not used in the 
experiments on which figure 13 was based, lead the writer to believe 
that most strains of Pythium debaryanuwm taken from lesions in 
plants are ordinarily likely to prove rather virulent parasites on pine 
seedlings. It further appears that the variation in virulence between 
the different strains of P. debaryanum on pine seedlings is less than 
the variation in strains of Corticitum vagum. 


PYTHIUM INOCULATIONS ON UNHEATED SOIL. 


Inoculations with Pythiwm debaryanum were made in western 
Kansas on a fine sand containing little humus after treating the soil 
with acid followed by lime. Commercial sulphuric acid was applied at 
the rate of 14.8 c. c. per square foot of bed, followed two days later 
by 25.5 grams of air-slaked lime raked. into the soil (0.16 liter of 
acid and 0.274 kg. of lime per square meter). The acid was diluted 
before applying with 256 volumes of water. The seeds were sown 
in drills, and inoculum was placed in the drills at the time of sowing. 
Each unit involved approximately 11 linear inches of drill, and all 


52 BULLETIN 934, U. S. DEPARTMENT OF AGRICULTURE, 


received equal quantities of seed. Three strongly parasitic strains 
of Pythium ‘were used, and a total of 12 units of jack pine and an 
equal number of western yellow pine was inoculated with 12 inter- 
spersed units of each species as controls. The mean results are as 
follows: 

Pinus banksiana.—Inoculated plats: Emerged, 64.2+4.9; died during the next 
17 days, 25 per cent. Control plats: Emerged, 85.5+3.6; died during 
the next 17.days, 18 per cent. 

Pinus ponderosa.—Inoculated plats: Emerged, 34.6+£1.8; died during the next 
9 days, 39 per cent. Control plats: Hmerged, 45.4+1.3; died during the 
next 9 days, 25 per cent. . 

The difference in emergence apparently due to the inoculation is 

for the first species three and one-half and for the second nearly five 
times its probable error. While, of course, 12-unit means are in- 
sufficient to allow the calculation of entirely reliable probable errors, 
they give some idea of the amount of variability of the results and 
the confidence which can be given them. It is impossible to give any 
such expression applying directly to the damping-off percentages and 
their differences, for the reason that averages for this item have 
been made in the writer’s work not by averaging the percentages for 
the individual units but by totaling all the seedlings and the dead 
seedlings on the plats to be averaged and recalculating the percent- 
age from these figures. This seems the only safe method, as other- 
wise units in which germination is low by accident or by the action 
of parasites will be given an influence on the resultant mean entirely 
disproportionate to the number of seedlings which they contain. 
Average values for damping-off obtained by this method and by the 
method of averaging the percentages of the individual plats or pots 
are often very different; it not uncommonly happens that the units 
in which germination is lower than the average also have especially 
high damping-off percentages, both phenomena being caused by an 
unusual activity of parasites. In such case to average the percentages 
themselves usually gives a higher damping-off figure than to total 
the seedlings for the different units and redetermine the percentage, 
and the latter practice is considered the better. In the present case 
the differences in the damping-off percentages obtained by the two 
methods are not great. The figures obtained by averaging the per- 
centages of the ultimate units are as follows: 

Pinus banksiana.—Inoculated, loss 30.9+5.0 per cent; controls, loss 13.2+2.8 
Ogr cent. 

ae ponderosa.—Inoculated, loss 40.05.1 per cent; controls, loss 24.1+3.3 
per cent. 

The differences between the inoculated and control plats in damp- 

ing-off percentage were for the first species a little over and for the 
second a little under three times their indicated probable errors. 


DAMPING-OFF IN FOREST NURSERIES. 53 


The results in general make it appear that the Pythium was able to 
kill some pines both before and after their appearance above the soil 
surface on the soil treated with the acid and lime. The control in 
this experiment did not receive the nutrient substratum added with 
the Pythium inoculum, but an experiment run under the same con- 
ditions at nearly the same time, in which seven strains of hyphomy- 
cetes with the same substrata entirely failed to decrease survival, 
indicates that the rice subtratum was not in itself the cause of the 
observed result. The rather weak action of the Pythium in these 
experiments stands out in sharp contrast to the results with Corticium 
vagum in the same experiments, practically all emergence being pre- 
vented by most of the Corticium strains used, some of which had 
proved less active than Pythium in tests on autoclaved soil. 

In a soil in Nebraska, somewhat similar but with more humus, 5.5 
ce. c. (three-sixteenths fluid ounce) of sulphuric acid per square foot 
applied in solution at the time of sowing had been found greatly to 
decrease damping-off. In different parts of beds treated with acid 
from 10 to 17 days earlier, 96 plats, each 3 inches square, were laid 
out, and each plat was inoculated at the center. Interspersed with 
these were 96 plats set apart as controls. Emergence had already 
begun at the time of inoculation. Jack pine, red pine, and Corsican 
pine were the hosts, and three Pythium strains of known parasitism, 
growing in pieces of prune agar the.size of peas, constituted the 
inoculum. The damping-off after emergence was less than 1 per 
cent higher for the inoculated plats than for the controls. Even such 
a light inoculation would probably have given some results in auto- 
claved soil, so the experiment indicates, as would be expected, that 
this acid-treated soil was less favorable for Pythium debaryanum 
than. steamed soil. 

On pots containing entirely untreated soil the following series of 
inoculations were made at the time of sowing the seed : 

Inoculation at one point in each pot: 

Experiment 25. Jack and western yellow pine, 1 pot of each inoculated ; 
survival 13 days after emergence slightly greater in both than in the 
six controls. 

Experiment 27. Jack pine, 78 pots, 27 controls; average emergence, 59 
in inoculated pots and 56 in controls; damping-off, 39 per cent in 
inoculated pots and 87 per cent in controls. 

Experiment 29. Jack, Corsican, and western yellow pine, 112 plats in- 
oculated just aS emergence commenced instead of at seed sowing, 
as in other cases, and 112 controls alternating with them; damping- 
off was less in the inoculated plats than in the controls. 

Experiment 31. Jack pine, 8 pots inoculated,'8 controls; inoculated, 
emergence 33 per cent, damping-off 13 per cent, survival 198; con- 
trols, emergence 38 per cent, damping-off 26 per cent, survival 196. 

Experiment 58A. Jack pine, 5 pots inoculated, 5 controls; inoculated, 
emergence 59 per cent, damping-off 32 per cent, survival 40; controls, 
emergence 51 per cent, damping-off 12 per cent, survival 45. 


54 BULLETIN 934, U. S. DEPARTMENT OF AGRICULTURE. 


Inoculations at two points in each pot: 

Experiment 26A. Jack pine, 3 pots inoculated, 4 controls; inoculated, 
emergence 29 per cent, aS compared with 89 per cent in the controls; 
subsequent damping-off the same in both. 

Inoculations at four points in each pot: 
Experiment 58B. Jack pine, 5 pots inoculated, 5 controls; inoculated, 


emergence 51 per cent, damping-off 10 per cent, survival 46; controls, 


emergence 48 per cent, damping-off 22 per cent, survival 34. 
Experiment 59A. Jack pine, 5 pots inoculated, 5 controls; inoculated, 

emergence 55 per cent, damping-off 2 per cent, survival 54; controls, 

emergence 50 per cent, damping-off 8 per cent, survival 46. 

Of these experiments, No. 29 was in the original fine sandy soil 
of a nursery in Nebraska in which Pythium is commonly found 
native and damping-off losses are usually heavy. Experiments 58A 
and 59 were conducted on soil from the same source which had been 
kept dry in the laboratory for five years; experiments 25, 27, 31, 
and 58A were on greenhouse mixtures of sand and soil. In experi- 
ments 31, 58A, 58B, and 59 parallel inoculations were made on auto- 
claved portions of the same soil, with definitely positive results in 
three of the four cases. In the heated soil the results were positive, 
not only because of smaller losses in the controls but because the losses 
in the inoculated pots were actually heavier in the sterilized soil than 
in that untreated. 

Inoculations broadcast : , 

Experiment 31. Jack pine, 8 pots inoculated, 8 controls; inoculated, 
emergence 31 per cent, damping-off 39 per cent, survival 129; con- 
trols, emergence 38 per ‘cent, damping-off 26 per cent, survival 196. 

Experiment 59. Jack pine, 5 pots inoculated, 5 controls; inoculated, 
emergence 58 per cent, damping-off 22 per cent, survival 45; controls, 
emergence 44 per cent, damping-off 2 per cent, survival 43. 

Even with these broadcast inoculations the results on untreated 
soil were too indefinite to allow the drawing of positive conclusions. 
In both experiments much heavier losses than these resulted from 
inoculations on steamed soil. It is evident that experiments on steril- 
ized soil do not always show what can be expected on ordinary soil. 
The same thing is indicated by the results of Edgerton with tomato 
wilt (36). 


CONCLUSIONS AS TO THE PARASITISM OF PYTHIUM DEBARYANUM. 


Pythium debaryanum has been found in low-altitude nurseries in 
all the species of conifers from which a serious effort has been made 
to obtain it, and its parasitism has been indicated in autoclaved soil 
on all of the conifers on which inoculation has been attempted. 
Therefore, although the work reported has been limited to a relatively 
small number of hosts, it seems likely that it will be found able to 
cause damping-off in most of the species of the Abietoideze which 
suffer seriously from the disease. Just how active as a parasite it is 


. 
. 


DAMPING-OFF IN FOREST NURSERIES. 55 


under ordinary nursery conditions is yet to be proved. The results 
in inoculations on disinfected soil, together with the frequency with 
which the fungus has been isolated from seedlings in the nurseries, 
lead the writer to believe that it is an important cause of disease in 
the seed beds. Further experiments on unheated soil, however, are 
considered desirable. 


RHEOSPORANGIUM APHANIDERMATUS. 


CULTURAL STRAINS. 


A culture of a parasite on radishes and sugar beets, described by 
Edson (39) under the above name, was obtained from him, and an- 
other strain, shown by Edson’s records to be a subculture from the 
same original strain, was furnished by the department of plant pathol- 
ogy of the University of Wisconsin. In parallel cultures on solid 
media this fungus proved in many ways remarkably like Pythiwm 
debaryanum, reacting in practically the same way to the different 
media on which it was grown both in relative growth rate and in 
spore production. Mycelium, chlamydospores, oogones, antheridia, 
and oospores are not recognizably different from those of Pythium 
debaryanum. ‘The oospores have seemed on the whole slightly larger 
and the mycelium a little more inclined to aerial growth than most 
of the Pythium debaryanum strains, but neither difference was sufli- 
cient to have diagnostic value. Swellings of the hyphe occurred at 
points in contact with glass, just as with Pythiwm debaryanum (PL I, 
figs. 5 to 7). 

In liquid cultures the Rheosporangium was readily distinguished 
from Pythium by the formation of the presporangia described by 
Edson. Autoclaved cylinders of turnip, 15 to 20 mm. long, cut with 
a 5-mm. cork borer, proved convenient bases for growth of both 
Rheosporangium and Pythium in water culture and quite as satis- 
factory as sterilized beet seedlings. Presporangia were also pro- 
duced in autoclaved soil, and in a single lot of corn-meal agar they 
were formed abundantly in the agar in Petri dish cultures. In none 
of the writer’s cultures, either with flies, sugar-beet seedlings, or 
turnip cylinders as nutrient bases, were mature escaped sporangia 
or swarm spores commonly produced. 

The Rheosporangium was not obtained in any of the numerous 
cultures made from coniferous seedlings or from seed-bed soil. 


INOCULATION EXPERIMENTS. 


The Rheosporangium cultures above referred to, strain 229 fur- 
nished by Dr. Edson and strain 351 received from the University of 
Wisconsin, were tested on pine and red-beet seedlings, with parallel 
inoculations with Pythiwm debaryanum. The results appear in 


Table VI. 


56 BULLETIN 934, U. S. DEPARTMENT OF AGRICULTURE. 


TABLE VI.—Results of parallel inoculation with Rheosporangium aphaniderma ] Ws 
and Pythium debaryanum on pine seedlings in autoclaved soil. . 


Experiment number, host, and inoculating fungus.¢ pl 
No, 30, Pinus ponderosa: 
Rheosporangium, Strain. 220\2 ot ee tomes eee een Ae 5 
Pythium, Dstrains.:'.: 200 Sue) Teeter 5 
Contnolses oss. a ne coc Pee eee ae ee ee 5 
No. 31, Pinus banksiana: 
Rheosporangium Strain 2292 peek | Tee SAAN ee 5 
Pythium, straint 205. 719. bao es Ma Pi So engi dS et 10 
COD TTOIS 0. «6,46 6 Anat Atos te Bi etc oc) 2 = Maem cea ete ate ana 25 
No. 58, Pinus banksiana: 
Rheosporangium, SUTain 2295 ic 26s ee eee eee 5 
Pythium, 8 Stislns hc aly ee nels ee Se St ER Se 40 
Controle: 22423, 0540 A a ee ee eee 10 
No. 59, Pinus banksiana: 
Rheosporangium, Stritm 2200) ech e a es ee ee | eee 5 
Pythium, 8 BErSling JA ot os arcee Mech eeeN as ofa | a GAS arches 40 
Controls: 242442. SAT AE eee i ee ee ee ee 10 
No, 61, Pinus banksiana: 
Rheosporangium, SUPAiM Soli axo a. Soe e eee ee ee one eee 20 
Pythium, 2 SiTAMIS.. co) ce caida ed ee ode ee 20 
Controls. rhs be es ee eee eee eee eee oe 20 
No. 61, Pinus banksiana and beets in same pots: 
Fines} eheosporangium, strain Shll;.7. ee aetcne vee eee sees 5 
No. 61, beets alone: 
Rheosporangium, Strainisol 64. sacee cae eeeee ean eee 5 
No. 62A, beets: 
Stray 220. se 2 eae ae ee 15 
Rheosporangium/{ Strain 351 Se. eee ee ee ee 4 
Py tham, 2. Strains os) 8 ee ec ea i ee 20 
Controls! 220... Oe eee) 5 See fe ee eee ee 11 
No. 62A, beets: 

: SETA 2298S... eee case ee eat oe eee 5 
Rheosporangium Stitt Gals: <<. ea ee | ee 5 
Controls) 222 Mae ee Ae. Pee eee eee 5 

No. 62A, beets and Pinus banksiana in same pots: 
Fines\r heosporangium, Straini229) aoe kee Se tees 5 
Pines Rheosporangi strain 351 5 
Beets Pp g1um, 5 1 OL... 2 ee eee ee eee eee o 
Beetsycontrols 3 caoeih ab Se. Sot Sg o Aneeane 2 eee 5 
No. 62B, Jack pine: d@ mes f 

. strain! 229% oo eee pee te oer 
Rheosporangium| strain SSL CRT Vir oes (Cope ae 5 
Pythium, Strain 258.3... 5...022 -ehigndtas gow eles a eras 2 
Controlssve5- -k se nee eee a2 cee cee eee ae ee 3 

No. 66, Jack pine: ae 
Bieogporanginm Tam | >see g ss 3 
Pythinm, 47 strains and substrains=... .s2e--- 2------ aaa 235 
ContTols: sj Ab acaeclhl thao oe. Teele alee ae ae 25 

No. 67, Jack pine: 

‘ Strain 229). . 1614.52 2082 seb oe eee eee 5 
Rheosporangium{St"ain gap ta. Shy i. 3)? oe 5 
Pythinm, 47 strains.and Substrains.- ese ee eee 235 
Controiss. 5. oe ee ee ee eee 23 

No. 68, Red pine: 3 

. Strain 229. he . ates J Boe eee eee eee 
Rheosporangium{<train Bei: Poa eee 5 
Pythium, 47 strains and'substrains: es. . eas] ae eee 235 
Comtrols. 52. ¢62P By ee A ee ee 


a Location of the inoculum: In experiment 30, at one point at the edge of each pot; in experiment 31, 


Results. 


Emerged |Damping-| Survival - 


(per cent | off (per 


ofseed). 


Per pot. 
2 


unit. 


over the entire pot; in all other experiments, over one-quarter the area of each pot. 


b The breakage of the one seedling not killed while sprouting prevented the determination of results. 

c Double seed density in these poke emergence and survival figures halved to allow direct comparison 
ensity may explain in part the higher loss in strain 351 than in strain 229. 

d Experiment 62B was conducted at the same time as 62A, but with a different soil. 


with otherunits. This highseed 


Table VI shows that in experiments 30 and 67 the loss was less in 
the Rheosporangium pots than in the controls and that in experiment 
68 the results were entirely negative, while in the remaining seven 


cent). 


Per pot. 


) 


(per pee 
ofseed). 


Per pot. 
peel eS. 


DAMPING-OFF IN FOREST NURSERIES. 57 


experiments the losses were heavier in the Rheosporangium pots. 
Especially in experiments 61 and 62A the evidence indicates very 
strongly that both germination loss and subsequent damping-off of 
the seedlings which come up can be caused by inoculation with Rheo- 
sporangium on jack pine under favorable inoculation conditions. It 
is, however, obvious that in all of the experiments the parallel in- 
oculations with Pythium debaryanum gave much more positive re- 
sults. The Pythium was active under conditions in which the Rheo- 
sporangium gave no evidence whatever of parasitic capacity. It 
furthermore appears that the two strains of Rheosporangium, though 
probably identical originally, differed in virulence at the time of 
their comparison in these experiments. The greater virulence of 
strain 351 was quite distinct in most of the comparative tests on beets 
as well as on pines. The possibility that the original culture was 
really a composite of two or more strains, of which different ones 
survived in the subcultures kept at Washington and Madison, re- 
spectively, seems worth considering. Such an accident might also 


-_ have been responsible for the divergence of Pythium strains 131 and 


295 referred to in another section. 

Further evidence of the parasitism of Rheosporangium was ob- 
tained in inoculations with cultures reisolated from seedlings killed 
by the original strains in experiment 62. Typical Rheosporangium, 
identified by presporangium formation, was easily recovered from 
the damped-off seedlings in pots of pines only, those of beets only, 
and the pots in which both hosts were sown. The recovery of a 
virulent Pythium strain from a single one of the pots inoculated with 
the weaker Rheosporangium shows that despite the absence of dis- 
ease in the controls a slight amount of contamination did occur. 
However, the comparative ease with which the Rheosporangium was 
isolated from seedlings in other pots inoculated with it and the fact 
that it has never been obtained in the numerous cultures made from 
controls and from pots inoculated with other organisms leave little 
room for doubt that the strains isolated were really recoveries of the 
Rheosporangium used in the original inoculations. The results of 
reinoculation with these strains are shown in Table VII. 

From Table VII and by comparison with Table VI it appears— 

(1) That in one experiment each on jack pine and red pine the reisolated 
Rheosporangium strains gave positive results. In a second experiment on jack 
pine (No. 67) the difference between the Rheosporangium pots and the con- 
trols was not significant. 

(2) That, as in Table VI, the Pythium strains used proved on the whole 
decidedly more parasitic than the Rheosporangium strains. In experiment 66 
this is not shown by the percentage of seedlings damped-off, but is sufficiently 


evident when the germination loss as well as the subsequent damping-off per- 
centage is considered, the survival being here, as in most other cases in which 


58 BULLETIN 934, U. S. DEPARTMENT OF AGRICULTURE. 


either of the groups of pots compared is seriously affected by parasites, the 
most convenient index of the comparative activity of the fungi used. In such 
a comparison as that between the Rheosporangium pots and the controls in 
experiment 68 (Table VII), accidental variations in emergence, of course, over- 
shadow the slight effect of the fungus, and the definitely determinable per- 
centage of loss after emergence is the only value which can serve as a basis for 
any definite conclusion. | 


TABLE VII.—Results of inoculations on pine seedlings with initial and reisolated . 
strains of Rheosporangium aphanidermatus compared with parallel inoecula- 
tions with Pythium debaryanun, 


Experiment number, host, and Num-| Num- 


inoculating fungus. Reisolation source. ee f Mer Emer paw “or | Survival 
pots, (per Epo a oa (per 5-pot 
t). | cent) ee 
a an ee ee 
No. 66, Pinus banksiana: 
Rheosporangium— 
Obra 229 scesam se ace een Edson from beet......-- 5 1 63 9 58 
SiTalMBol peseuek eae oes alee e Ot (22. ctiert ee Bee 5 1 80 52 39 
Strains 403 and 404........ Strain 229 from beet..... 10 2 78 43 44 
Strains 405, 406, and 407.-.-.| Strain 351 from beet..... 15 3 63 43 36 
Strains 417, 430, and 433...| Strain 351 from pine..... 15 3 72 42 41 
DVOTORO so: = = cs sate See eee ene ee eae 50 10 |. 7042.7 40 4243.8 
SSS ESS Sa ee ee 
COpbrOlsi. = Got cc hak oe oe ce ee ee ee ee eee 2D) lee- eRe 75 15 64 
Pythitimys averages..it Lee bees sits Soe eee te eae 235 47 43 . 33 29 
No. 67, Pinus banksiana: 
Rheosporangium— 
Sprain 20 F ees! Fee Edson from beet......-. 5 1 107 0 107 
PULA Sole. | Saree less 0 Cee eee rs 5 1 88 6 83 
Strains 403 and 404.......- Strain 229 from beet...-. 10 2 91 8 84 
Strains 405, 406, and 407...| Strain 351 from beet... -- 15 3 92 4 88 
Strains 417, 430, and 433.-..| Strain 351 from pine..... 15 3 83 3 80 
A VETA ROS IF ale See. AL eee te 50 10} 90+2.4 4 8642.9 
Controlss2 eeu. 8. Se Sores cee cee ee eee oa ie) ate 87 5 83 
Py tien, AVOTAPC.«... 5). nase es te eee eee ee eee 235 47 51 26 38 
No. 68, Pinus resinosa: ry 
Rheosporangium— 
Straim2290 eos. . .5 sae eee Edson from beet....-.--- 5 1 105 0 105 
Strains ct Vice ec ee leon COl 2 few cee eean soe 5 1 124 0 124 
Strains 403 and 404........| Strain 229from beet..... 10 2 102 1 101 
Strains 405, 406, and 407...| Strain 351 from beet..... 15) 3 105 5 100 
Strains 417, 430, and 433...| Strain 351 from pine...-. 15 3 100 3 97 
Average SOP ss si) OO ae SA Oe ores - 50 10 | 105+2.3 2) 10242.5 
Controls... 202 829% 6 2s secede theca eee ae ee eee 1Salcee seaeee 104 0 104 
Pythitim, average, «ces 7 dose ae et oe oe ee eee eee 235 47 86 27 63 


A frequency graph based on the survivals of the 50 individual pots 
inoculated with Rheosporangium in experiment 68 yields a rather 
interesting asymmetrical curve (fig. 17). The shape of the curve 
is taken as indicating that in a large number of the pots the inocula- 
tion produced no effect, while in the smaller number of pots in which ~ 
the inoculation apparently “took,” the loss was rather heavy. This 
is a rather common phenomenon in:inoculations which are only 
partly successful, part of the pots being free or practically free from 
loss, while others are nearly cleaned out. It will be seen again in 


DAMPING-OFF IN FOREST NURSERIES. 59 


figure 18. This suggests, further, that part of the lack of activity 
was due to the failure of the fungus to maintain itself vigorously 
in the soil till the pines reached a stage of sprouting in which they 
could be readily attacked. Direct inoculations after the seed starts 
to sprout are therefore desirable to supplement the experiments 
reported. The survivals in the controls did not show any such 
asymmetrical distribution. 

While the Rheosporangium has given rather definite evidence of 
parasitism on Pinus banksiana under favorable conditions, the 
activity of the strains available has been much less than that of the 
Pythium debaryanum strains. In view of the fact that the fungus 
has not so far been isolated from pine it can be concluded to have no 
general importance ! 
in pine seed beds. Its 
very rapid growth on 
prune agar makes it 
very easy to isolate 
when present. 


.) 
(eo) 


N 
Oo 


PHYTOPHTHORA SPP. 


~ 
Ss 


Phytophthora fagi 
R. Hartig has-been 
commonly reported 
as the cause of death 
of seedlings of va- 


FERCENTAGE OF POTS 


10 13 16 19 22 25 28 3. 34 

SEEDLINGS SURVIVING PER POT 

Fie. 17.—Diagram showing the results of inoculation of 
Pinus resinosa seedlings with Rheosporangium aphanider- 


rious plants in Eu- 
rope, including con- 
ifers and herbaceous 
plants as well as 
beech (5, 8, 15, 55, 
56, 57, 59, 78, 104.) 


matus, as indicated by the number of seedlings surviving 
in inoculated pots (solid line) and control pots (broken 
line). The shape of the curve for the inoculated pots is 
taken as indicating that a large proportion of them 
were entirely unaffected by inoculation, while those which 
were at all affected suffered considerably. This is a 
frequent result in inoculations with weak parasites added 
at the time of sowing the seed. 


It has been grouped 

with the rather indefinite Phytophthora omnivora and with P. 
cactorum, the enemy of cactus, ginseng, and other plants. Wil- 
son (147, p. 54) considered it distinct, but Rosenbaum (114), 
in his biometric comparison of Phytophthora cactorwm and a 
single strain of P. fagi, failed to find significant morphological 
differences. If P. fagi is even physiologically different from 
the American strains of P. cactorum, its introduction into the 
United States is to be guarded against. There is certainly no 
fungus in the United States causing the damage to coniferous 
seedlings which European reports have attributed to P. fagi there. 
As P. fagi attacks roots, it presumably can be carried in soil as well 
as on plant parts. 


60 BULLETIN 934, U. S. DEPARTMENT OF AGRICULTURE. 


A test made on jack pine with a culture of Phytophthora cactorum, 
furnished by the department of plant pathology of Cornell Univer- 


sity, resulted negatively. At the time of sowing the seed three pots 


were inoculated with cultures on nutrient agar inserted at several 
points in each pot. After emergence additional fragments of prune- 
agar cultures were placed in contact with the seedlings, and they were 


POTS tW/7TH/ . 
PYTHIL/T 


‘ 

5 

q 

X40 POTS WITHOUT : 
. PYTHIUM } 

iy 

& 

30 


a 

8B 

O-/F- 18-24 GO-F4 FE-59 60-74 75-89 90-10F 
SLLDOLINGS SURVIVING FER POT 


Fig. 18.—Frequency of pots with different numbers of surviving seedlings of Pinus 
banksiana, inoculation experiment No. 81. The solid lines represent pots to which 
cultures of saprophytic organisms were added. The broken lines are based on pots to 
which no saprophytes had been added. The solid lines are based on 78 pots in the 
upper graph and 80 pots in the lower one; the broken lines on 33 pots in the upper 
and 25 pots in the lower graph. Pythiwm debaryanum was added just after sowing the 
seed at a single point in each pot represented by the two upper lines. Cultures of 
saprophytes were applied broadcast two days before the Pythium inoculations were made. 


sprayed with a spore suspension. The pots were covered with glass 
to increase atmospheric moisture, and the seedlings were occasionally 
sprayed with an atomizer. The soil was an autoclaved mixture in 
which simultaneous inoculations in a different room with Pythium 
and.Corticium proved successful. The failure of the Phytophthora 
may possibly have been due to the lower temperature at which the 
pots incculated with it were kept (15° to 20° C.). | 


DAMPING-OFF IN FOREST NURSERIES. 61 


A species of Phytophthora was isolated by Mr. R. G. Pierce from 
damped-off Pinus resinosa in Minnesota and used in four inocula- 
tion experiments, the results of which appear in Table VIII. In the 
first of these experiments unboiled water was used on the pots, and 
mice obtained access to the pots of the second test. Probably as a 
result of these things infection occurred in the controls in both cases, 
and the results were inconclusive; in the later experiments these 
two sources of infection were eliminated, and in experiments 68 and 
72B the controls were free from disease. Parasitic activity was in- 
dicated rather strongly in experiments 68 and 72 (on P. resinosa and 
P. banksiana) and to a certain extent in experiment 66. In experi- 
ment 67 it was evident that the Phytophthora was nearly or entirely 
inactive. Comparison of the results in experiments 66 and 68 with 
the results from inoculations with Lheosporangium aphanidermatus 
in the same experiments (Table VII) suggests that the Phytoph- 
thora may be better able to attack the pine from which it was isolated 
than the Rheosporangium, while the latter fungus caused consider- 
ably more-destruction to Pinus banksiana than the Phytophthora. 
Comparison of the results in the pots inoculated with Phytophthora 
and those inoculated with Pythiwm debaryanum in all the experi- 
ments indicates that the Phytophthora strains used were less virulent 
than most of the strains of P. debaryanuwm and very certainly less 
destructive than the most active strains,of either P. debaryanum or 
Corticium vagum. This species of Phytophthora has been reisolated 
from damped-off Pinus ponderosa in experiment 72. 

Direct inoculations of the stems of seedlings of Pinus resinosa soon 
after they emerge from the soil have so far confirmed the lack of 
parasitism of Phytophthora cactoruwm and of the cultures of Phy- 
tophthora sp. grown by the writer. The identity of this species has 
not yet been determined. It is able to grow only about one-fourth as 
rapidly as Pythiwm debaryanum on the medium which has been 
used for isolation and may therefore be more common in the seed 
beds than the small number of isolations by the planted-plate method 
would indicate. However, its oospores, larger and darker than those 
of Pythium debaryanum (usually over 20 yin diameter), should have 
been recognized in the routine microscopic examination of planted- 
plate cultures had this species been frequently present, even if it 
had not grown fast enough to get out ahead of the other organism 
and allow isolation. It is not believed that it is common enough in 
pine seed beds to be of importance, even if other strains should be 
found more virulent than those which have been available. 


MISCELLANEOUS PHYCOMYCETES. 


A fungus, apparently referable to the somewhat indefinite Pythium 
artotrogus (Mont.) De Bary, was isolated by Mr. Glenn G. Hahn 
from Pinus resinosa in Michigan and from damped-off Pinus bank- 


62 BULLETIN 934, U. S. DEPARTMENT OF AGRICULTURE. 


stana *n pots of autoclaved soil which had received tap water at 
-Washington, D. C. It agreed both in the appearance and measure- 
ments of its spiny oogones and smooth oospores with Pythiwm arto- 
trogus (P. hydnosporus) as described and figured by Butler (23). 
In addition to the spores which Butler describes, there appeared in 
apparently pure prune-agar cultures of different strains bodies with 
smooth walls, of somewhat irregular ovoid outline, and mostly larger 
than either oospores or oogones. They are very much less abundant 
than the sexual spore forms. Their greatest diameter varied from 
11 p to over 40 y. The germination of these bodies was not observed. | 
Efforts to induce the fungus to produce swarm spores by growing 
them in liquid nutrient media and transferring them to pure water 
were unsuccessful. This failure to produce zoospores is further in- — 
dication of.the identity of the fungus with that described by Butler, 
who says that asexual reproduction is unknown. . 

The strain from Michigan was a rather weak growing organism, 
difficult to maintain in tube cultures without rather frequent trans- 
fers. Its parasitic activity in the experiments reported in Table VIII 
is nil or negligible. Because of the poor seed and small number of 
seedlings involved in experiment 72B, the percentage of damping- 
off there given means only a single seedling dead. The Washington 
strains, on the other hand, though evidently not strong parasites, did 
apparently cause the death of a number of seedlings. The best evi- 
dence of this is.in experiment 68, in which there was damping-oft 
in each of the five 5-pot units containing the Washington strains and 
none in any of the 18 control pots. The available strains were less 
active not only than Pythium debaryanum, but less than the Rheo- 
sporangium and Phytophthora strains used. The fungus is be- 
lieved to be a potential parasite on pine seedlings, but not one of any 
general importance. What is probably the same fungus had ap- 
peared in the writer’s cultures from western nurseries in conjunc- 
tion with P. debaryanum, but-not commonly, and it had not been 
isolated. While its growth rate is only about half that of Pi. debary- 
anum on prune agar, it is nevertheless so much faster than that of 
many fungi that it should have been more often obtained in culture 
were it at all common in damped-off seedlings. 

Another fungus, presumably an oomycete but producing only 
chlamydospores in the writer’s cultures, was obtained from damped- 
off olive seedlings furnished by Prof. W. T. Horne and from soil — 
direct, both at Berkeley, Calif. The fungus is apparently. the same* 
as one which has been occasionally seen in cultures from pine seed- 
lings in the Middle West, but had not before been isolated. The 
hyphe are ordinarily moneapene and the growth on corn-meal agar 
is superficially much like that of Pythiwm debaryanum, but with 
greater tendency toward local zonation and aerial growth and less 


DAMPING-OFF IN FOREST NURSERIES. 63 


than half as rapid. Chlamydospores are mostly intercalary, at first 
subspherical, soon becoming polygonal, and after a few days they 
shrivel and exhibit thick, angular walls. In size the unshrunken 
spores usually lie between 8 and 12 » in diameter, but bodies as 
‘large as 20 p occasionally occur. Antheridia have not been observed, 
and the shriveled bodies are not believed to be oospores, though the 
observations made have not been sufficient to exclude such a possi- 
bility. No other spore form was obtained in water culture, using 
various nutrient substrata. In inoculation the strain from olive (the 
“undetermined Phycomycete” included in Table VIII) has given 
negative or nearly negative results in three inoculation tests in which 
other fungi gave positive results. In a test not included in the table, 
in which Pinus ponderosa was the trial host, damping-off was slightly 
higher in the inoculated pots than in the controls, but the difference 
was apparently due to accidental infection with Botrytis and 
Pythium debaryanum. As all the seedlings in pots inoculated with 
P. debaryanum in this additional experiment were killed, the rela- 
tive unimportance of this strain of the small-spored fungus was 
further indicated. An additional test of both the olive strain and 
the strain from soil was made by inoculating seedlings of Pinus 
banksiana and P. ponderosa growing on filter paper in Petri dishes. 
Some of these were kept wet with water, some with an inorganic 
culture solution, and some with the inorganic solution plus peptone 
and dextrose. Agar cultures were applied directly to the seedlings. 
The seedlings inoculated with the small-spored fungus remained 
alive as long as the control seedlings, while parallel inoculations with 
Pythium debaryanum resulted in the early decay of the seedlings. 


TABLE VIII.—Results of inoculations with miscellaneous oomycetes on pines in 
autoclaved soil at the time of sowing. 


[In all the experiments included in this table, the inoculum consisted of fragments of agar cultures 
distributed with the seed at one side of each pot over about one-fourth of the pot area. The controls 
received sterile agar in the same way.] 


Results. 
Num- 
Experiment number, host, and inoculating fungus. ber of 
pots. lmmerged ot 4 Survival. 
No. 66, Pinus banksiana: Per 5-pot Per 5-pot 
Phytophthora sp.— unit. |Percent.| wnit. 
SUL BI SECs 2 See Aa A I a Ae a Melee 8 Ve nk an vee 5 70 30 4 
SHINE B.S OEP a Pee ee ee Goons Saat eae 5 75 28 54 
if PAD ATUMO OPO eee nn A oe ye Se ee ee Br 5 94 16 79 
Pythium artotrogus (?), Michigan strain. ...................... 4 115 14 99 
Wmnaetemmned, Phycomycete..........----.--csee+eedecesceee- 5 83 9 76 
CPN EUTTO IS cai ae ¢ CRE GE ee EE 2 os ee 25 75 14 64 
No. 67, Pinus banksiana: 
Phytophthora sp.— 
SUI, SSS ee ee a eee i. Seen 5 96 1 95 
SNiettin 27 Ee ON a eee er eee eo ee x 88 3 85 
SADEATEIRS (0PM AMS sO cc ies NS noon nnd A at eee 5 99 0 99 
Pythium artotrogus (?), Michigan strain.........-...0....--.-. 5 102 2 100 
ndevermined Phycomycete.......-.2.....ccececceeceoccccene- 5 98 0 98 
RIE Re ee ie in hiaine nile sav and Py Sees ae ewe haeeec 23 87 5 83 


64 BULLETIN 934, U. S. DEPARTMENT OF AGRICULTURE. 


TABLE VIII.—Results of inoculations with miscellaneous oomycetes on pines in 
autoclaved soil at the time of sowing—Continued. 


Results. 
Num- 
Exporiment number, host, and inoculating fungus. ber of 
pots Damp- ; 
Emerged. ing-off. Survival. 
No. 68, Pinus resinosa: Per 5-pot Per 5-pot ° 
Phytophthora sp.— unit. |Percent.) wnit. 
ULI. Na ss setae nate sto ae eas Se ee ag oe eee eee 5 104 fi 97 
SLA. ONS i a eee Se ER. oy PEN A) eee 5 109 18 89 
SULTANS (OSC 52 ee ee te ee een eee eee eee ae 5 98 5 93 
Pythium artotrogus;(?); Michigan strains... 9.222) -2o. 52a 5 121 0 121 
Pythium artotrogus (?), Washington, D.C.— 
SLED? a oe ket nage SMe NS, YER RE ee Ae a 122 1 121 
SETA S 25 ee BEATE EONS gh eee te eee ee eee 5 120 9 109 
OL: 100.) one ae a ee eee eee) Sc oe 5 96 5 91. 
Sirain Gao. us 55) eR Mee ee Pee 5 “110 6 103 
SUTAIN B33. nS blersa) acc Ootdha ieee teas ees ee es ae = ee oe 5 94 1 93 
Undetermined’ Phycomycetéet-+--8e2. oes eee ee ee eee ii 84 2 82 
COMLTONS: 1 2. 0 don aoc eke cl dvenbeels reseb bape seuss 18 104 0 104 
No. 72A, Pinus resinosa: Per 3-pot Per 3-pot 
Phytophthora sp.— ' unit. unit. 
SUAS 128 Me Sk A EL ee a 3 20 35 13 
Pythian artotrogzus (7), Michigan stra: .--c2 se) se ess see e eee 3 62 0 62 
Pythium artotrogus (?), Washington, D. C.— 
train o2ie = eee fee pie Ba ig hg eth ee ede a entre sit! 2 45 7 42 
eit eo! ne ae ae ee Ree ee aE 3 37 0 37 
Strain Sg 2a eae. Se ee? See, eee ee eee 3 40 25 30 
Controls: ....p2.08 i ade de! ot at be ie. ae ee eee 16 35 5 33 
No. 72B, Pinus ponderosa: 
Phytophthora, Sp:2344. 4 -o-e. o  ee ee 3 8 50 4 
Pythium artotrogus (?), Michigan strain. ...................... 3 13 8 12 
Pythium artotrogus (?), Washington, D.C.— 
Strain 821" 2.0325, 52. Qa oe ee eee eee eee 3 11 0 11 
Strait 83lts.. ee. coh be eee See ee eee eee 2 29 6 27 
Straim’833 34 24 2 ei ia ees cee ee eee | 2 6 0 6 
COnbrOIS. 5.2.2.0, ote. ow wa, cp ee eee Ue ce ae ae oo ee 14 9 0 9 


OTHER FUNGI. 


Data on the possible relation between various other fungi and the 
damping-off of conifers have been already summarized by Hartley, 
Merrill, and Rhoads (68, p. 546-550). Pestalozzia funerea on the 
basis of the experiments of Spaulding (135), Botrytis cinerea on the 
basis of observation and: very preliminary inoculations, and 7’richo- 
derma koningi on cultural-evidence only are all believed to be po- 
tential causes of damping-off, though not ordinarily important. AJ- 
ternaria sp. is under a certain amount of suspicion on account of its 
frequent association with the damping-off of conifers, but it has 


never been used in experiments. Mhizopus nigricans (incorrectly re-. 


ported as Mucor), 7'richothecium roseum, Rosellinia sp. from nursery 
soil, Chaetomium sp. from maple roots, strains of Penicillium and 
Aspergillus, Phoma betae, and Phoma spp. are all reported to have 
been used in inoculations with negative results. 

Since the publication of the above summary a preliminary success- 
ful inoculation experiment with Botrytis cinerea on recently emerged 
Pseudotsuga tawxifolia has been found briefly mentioned in an article 
by Tubeuf (140) on another disease. Further experiments with va- 


DAMPING-OFF IN FOREST NURSERIES. 65 


rious strains of Botrytis, both from conifers and from other hosts 
(the latter supplied by the departments of plant pathology of the 
California and New York (Cornell) Agricultural Experiment Sta- 
tions), have already yielded confirmatory evidence of the parasitism 
of B. cinerea. 

While a considerable number of fungi have been considered in the 
foregoing, it is entirely possible that there are still parasites which 
have received no consideration and that some of them may perhaps 
be important. The moist-chamber method of culturing parasites 
for isolation yields only those which produce spores readily; the 
planted-plate method is not well adapted to the isolation of slow- 
growing fungi or bacteria. It is suggested that in further culture 
work with damped-off conifers an attempt be made to secure slow- 
growing organisms by dilution plates of teased-up fragments of 
recent lesions. | 


RELATIVE IMPORTANCE OF. THE DAMPING-OFF FUNGI ON 
4 CONIFERS. 


The relative importance of the different damping-off parasites is 
something that has not been thoroughly investigated for any host. 
The most information on this point is that given by Busse, Peters, 
and Ulrich (22) for sugar beet. In this case they find the special- 
ized Phoma betae distinctly the most important, with Pythiwm de- 
baryanum second and Aphanomyces levis third. 

Peters (100) apparently considered Rhizoctonia unimportant as 
a cause of beet damping-off. The opposite was indicated by a small 
number of cultures by Edson (38) from beet seedlings on Kansas 
and Colorado soil. These yielded more Corticiwm vagum than any 
other parasite and no Pythium at all. Johnson (81) states that 
most of the damping-off of tobacco seedlings is due to Pythium 
debaryanum and Corticitum vagum. Atkinson (1), speaking for 
cotton in Alabama, and Sherbakoff (127, p. xcv; 128; 129), speak- 
ing for truck crops in Florida, make Corticiwm vagum the impor- 
tant damping-off parasite, with P. debaryanum. negligible. Horne 
(oral communication) found the same situation in tobacco seed 
beds in Cuba. Atkinson (3), in an article on trees, held that many 
of the cases of damping-off attributed to P. debaryanum are in real- 
ity due to C. vagum. Peltier (98, pp. 336-337) has reported Phi- 
zoctonia solani as the cause of damping-off of a large number of 
plants, recording his observation of the damping-off of seedlings of 
~ nearly 50 species of miscellaneous genera and cuttings of 13 different 
species, all of which he attributes to the Rhizoctonia. He does not 
state whether in this case he used diagnostic methods likely to de- 
tect Pythium debaryanum if it had been present. 

19651 °—Bull. 984—21 5 


66 BULLETIN 934, U. S. DEPARTMENT OF AGRICULTURE. 


For the conifers, no very reliable data on relative importance have 
been published. Numerous European reports emphasize the damage 
due to Fusarium spp., while a smaller number attribute loss to 
Phytophthora fagi or to both. There seems to have been little effort 
to determine the presence or absence of Corticium or Pythium, so 
these reports can not be given great weight. Spaulding’s evident 
belief (136) in the importance of Fusarium has more weight, as he - 
was on the lookout for the other fungi; the moist-chamber diagnostic 
method employed in most of this work was, however, not well 
adapted to the detection of either one. The same is true of the work 
of Rathbun (106), in which dilution plates of seed-bed soil were 
employed. Rankin (105) attributes to Fusariwm spp. the greatest 
importance in tree seed beds in this country, with Pythium debary- 
anum and Rhizoctonia spp. important in certain cases. Gifford (46) 
emphasizes the importance of Fusarium, while Clinton (28) appar- 
ently found Rhizoctonia (Corticoum vagum) especially prevalent 
in the examinations he made. 

On the basis of the data presented or summarized in this bulletin, 
it is believed that of the various organisms which have been con- 
nected with. damping-off in coniferous seed beds Pythium debary- 
anum, Corticium vagum, and Fusarium spp. include all of impor- 
tance. The others, either because of low indicated virulence or 
infrequent occurrence, and in most cases both, do not seem to merit 
extensive consideration. 

In order to form an idea of the relative frequency of the parasites 
named above as important, there have been brought together in 
Table TX the results of the examination of 488 damping-off foci in 
untreated beds and 304 foci which have appeared in beds which had ~ 
received various disinfectant treatments. The data are presented 
by foci rather than by individual seedlings, as was done in the census 
reported by Busse and his coworkers. Most of the diagnoses were — 
made by planting recently diseased seedlings in plates of solidified 
prune agar, all the seedlings taken from the same focus, or “ patch,” 
of damped-off seedlings being put into the same Petri dish. The 
resulting growth was in some cases transferred to a tube for later 
examination, but was usually examined directly in the plate. In a 
smaller number of foci the seedlings were macerated and examined 
directly without recourse to culture methods. As Pythiwm debary- 
anum does not commonly fruit in diseased seedlings of pine or of 
tobacco (81) and its hyphe are both difficult to find and not in 
themselves considered a sufficient diagnostic character, this latter 
method of examination is not so satisfactory for the determination of 
Pythium as it is.for Corticium, which is easily recognized by its 


DAMPING-OFF IN FOREST NURSERIES. 67 


thick-walled truncate-tipped hyphe and characteristic branching. A 
further difficulty in the direct-examination method, unless the seed- 
lings are sectioned, is in distinguishing between Corticium hyphe 
which are in the tissues and those outside. The well-known habit 
of the Corticium of sending hyphe superficially over the surface of 
plants which it is not appreciably injuring makes it evident that only 
hyphee actually found in the tissues have diagnostic value. Direct 
microscopic examination is, furthermore, very likely to fail to detect 
Fusarium. The planted-plate method therefore appears the better of 
the two, and the results of the culture diagnoses appearing in the 
lowest two lines of Table IX deserve probably more attention than 
. the total occurring a few lines above, in which the results of direct 
examination of the seedlings are also included. The high proportion 
of Corticium reported from the Michigan and Minnesota nurseries 
is probably due in part to the fact that most of the examinations 
made there were of the direct microscopic type. 


TABLE IX.—Results of the examination of damping-off foci in conifer ous seed 
beds for Pythium debaryanum, Corticium vagum, and Fusarium spp. 


Beds ofheated |Beds treated with 
Untreated beds. soil. strong acids. 
nig Number Number 
, showing— - | Showing— aS ing— 
Eepaping. : 2 < owing 3 howing 
A A A= 
Pla lseligia&igisis)8leidig 
s|EIB| Slee 2l8le/s/ sl 
od =e Oo i o — oO me o Ch Oo Lol 
4 Gq 3 as} — aq 3 3 — pe) or 3 
cS) = ei na (3) » EF nO i) » aes a 
S) ia o) =) iS) Bs oO.) a5 iS) mlo| x 
Fy S) Fy BR |e )/O;m | & 1% /o] 
ey petty: 

EAU ain no ms meme -- ~~ 4 3 i Pls, ASHES Se = Ou 0 2 
Pentre OlO.. 2-22-22 --------- 22 Q-)..19 OMe eaieeen| ns enmeleares|- ses|> ek sles 
: Monument, lh Se 34 Gn 20) el osleemn (ams 1. [eee clea salto scac|setos 

Garden City, Kans.— 
Garden City Nurseries.........-.:...--.- 18 4 0 9) alsa Sal) SOF Zi e28 (PL See 2 9 
Kansas Nurseries (sand)................- 20 4 9 daly Moms? a ON Gel eLGite 9. SO 8 
Ge es ee QIAA MPA | AS: Lode cone LOb|: Ol Ley | 299-34 | <2") GL 
(Coss Llgike, U0 Soe AQ 15: |) 21 Ie Bem Moe eerie ere tine Onan: 0 
Dundee, I o> Se GAS ent eae 4 0 4 Bullets SS Reh ae ke he eal mee tees Peer 
_ East Tawas, Mich.— . \ 
Beal Nurseries (Gand) owe eet rock ADs 42 | 33, PO A | eel ese See Ue a) 0 
ast eea was INUESerIeS....-.2.-.-.-.-:...-- fSealemelil 7 LD Bela a ames ete = 1335/5 16 2 
Washington greenhouse....-.-.-.....-...-. 12 3 3 9 | Celera O Nines ter lo. . sea ece 
Total: 
USNS ee aes See ee 438 | 184 | 162 | 204] 64]19; 0O| 33] 163 | 64; 12] 82 
(DS EDS ie SR a a a 100 | 42) 37] 477] 100] 30} 0} 52] 100/39] 5} 50 
By diagnostic methods: 
Direct examination— 
DUDLGUNO PS 5 oe oe eee Eee 156 39 | 108 | 25 US sal ee | aes 16 | 6 8 4 
Lo eae LOOSE oe G9) STG) Sores. 2. =o tes 100 | 38 | 50 | 25 
Planted-plate cultures— 
BICEAAN Teme ass, io oh oe ote 3 aie  ichstcrone ot oe 282)| 145 | 54) 179) 64) 19) O} 33] 147) 58) 4) 78 
RIE enone hss dbo tnw- pee oe 100! 51] 19] 631100] 30; O, 521100) 39] 3] 58 


68 


BULLETIN 934, U. S. DEPARTMENT OF AGRICULTURE. 


TABLE IX.—Results of the eramination of damping-off foci in coniferous seed 
beds for Pythium debaryanum, Corticium vagum, and Fusarium spp.—Con. 


Beds treated with| Beds treated with [Beds treated with 


formaldehyde. | copper sulphate. zine chlorid. All treated beds. 
Number Number Number Number 
. cet . showlng— . —— . — 
Groupee, = showing - howing + showing: - showing 
A A A= a= 
elalSi/Slalsisle|elajelela|s lgis 
o|SiI(S(B}+so |S18/8) & | 2 1s | aioe 
om | Olas] 8] en | OI] Sl en | Gls] oS] ow qgids]s 
cS) ~ ea 2) ° red ss n oO — = (3) » E n 
oih|BIS|/S |RIB1S | S97 B1 eS) See 
e/a }O;R |e |e l/Ol]me |] & |B lo] m& ] & Pati FR ees 
By locality: 
Berkeloy, Calif... -.22ccc}s ans clinch Boel care | prctel cee bee | See ale er 5 5] 0 2 
Manitou, Colo. 2. ...22..2.-|oscsc|occe| ose «|S of ce ceia|e ales ete o5| (Gare nll Sceie cle creel Meare ares | eee 
Monument, Colo... ... 2... .|.--+-[-008|-c=2]2c0n|oecas|-0ce|as 2] de nelen -o2] ccc a) sce] cates eee 
Garden City, Kans.— 
Garden City Nurseries...| 6] 0| 6] 3 LO On laect 3 |.'1.| 0): 3) 52) Taeeeeeiees 
- Kansas Nurseries (sand) 3. c<<-la2celaeccle cee foseera ea eo nero eaters eee) Cree ae 31| 11] 2) 14 
Halsey, Nebr.....-.---:-- 34 | 20| 11] 24 613). O55 8! 0] 0] 514s eee 
Cass Lake, Minm: . 2 /0...522]205]2 Soe) cca Game la tects eee Cpe ee eee eee 1 0; 0 0 
(Dandee Wil... teers ee eee sene|eccnlepcs|oesoclencc|-cen|eceuls a= anlecarelainelel ests aaa mle 
East Tawas, Mich.— 
Beal Nurseries (sand). ..|...-- pee ne, net (hs “ail ata ded Naa Gl atest eostetee | rare | eet ee 1 1) 0 0 
East Tawas Nurseries...| 8| 5] 4] 0 6/ 5] 3] 3 5 | 3} 0). 27) 262s senate th 
Washington greenhouse ...!...-- snwalecs nla sdalibccnfescd| Seed setae ae ea 7 200 3 
Total: 
INumbersse ee se- eee 48 | 25; 11] 27) 13] 8; 3]. 9] 16]. 44 0 | 10)))302)) 0m Robe eros 
Percentagens-5occ.. - 100 | 52 | 23 | 56 | 100 | 62 | 23 | 69 | 100 | 25} Oj] 63) 100} 39) 9} 53 
By clneceste methods: 
irect examination— t = 
Numberse5 2... ee Ss, eka 10 Se rebel Die 2 5] 3] O| 2] 34) 18) 14 8 
‘Percentages--e- seercnc: © 100 | 63 | 50) 0} 100] 80 | 40} 40] 100 | 60] Oj} 40] 100} 53] 41) 24 
Planted-plate cultures— 
Numibert sao. sesso 405 200) Se 7a) ear S| <4 1 "6 11 1 0] 8 | 270 | 102 | 12 | 153 
Percentage: tee... = oceee 100 |} 50 | 18 | 68 | 100 | 50] 13 | 88 | 100} 9] Oj 73 | 100| 38] 4] 57 


The data on the different nurseries do not allow any generalizing 
on the basis of locality except to say that all of the fungi seem quite 
generally distributed in the Lake States and Great Plains region. 
In general, it appears that the Fusaria as a group are more common 
than either of the other fungi; as they grow more slowly than either 
the Pythium or the Corticium, they were probably rather more 
common relatively than even the plate-culture method indicated. 
It also appears that the Pythium occurred in more foci than the 
Corticium in the beds examined. Further culture work,. perhaps 
by the method of dilution plates of fragments of lesions, seems de- 
sirable, especially in the East and the Northwest, regions in which 
there are large coniferous nurseries and in which nothing like a 
parasite census has been attempted. Observations on the type of 
focus occurring in most of the nurseries in the Rocky Mountains 
leads the writer to believe that Corticium will be found especially 
important there. . 

While the data on the fungi in foci in disinfected beds are insuffi- 
cient to serve as a basis for much in the way of conclusions for any — 
individual treatment, they in general agree with the assumption, — 
which knowledge of the fungi would favor, that Corticium is the 


DAMPING-OFF IN FOREST NURSERIES. 69 


most easily controlled by soil disinfection (see the bottom line in 
the last four columns of Table IX). Its poor adaptation for aerial 
dissemination would lead one to expect to find it seldom in beds 
treated with efficient disinfectants. The entire absence of Corticium 
in heated soil therefore seems somewhat significant. The rather 
high Corticium yield in the formaldehyde plats is of some interest 
in view of the reported inefficiency of formaldehyde in destroying 
Corticium vagum on potato tubers (48, 50). As will be noted from 
the data given, more than one suspected parasite was often found in 
what appeared to be a single focus. This was probably -in some 
cases due to independent foci being nearly concentric; it also in 
some cases undoubtedly means that one of the organisms found was 
only secondary. In the beet-seedling cultures by Busse and his 
associates, individual seedlings yielded two or more potential para- 
sites in 100 of their nearly 1,300 examinations. It not infrequently 
happened in the work on pine seedlings that no fungus recognized 
as a likely parasite could be isolated. This was especially true 
in plate cultures when Rhizopus or Trichoderma happened to be 
abundant, as both are very fast growing and often suppress para- 
sites. This is an additional reason for the development of some 
method as a dilution plate of lesion fragments for diagnosing damp- 
ing-off. 

Bon an accurate and complete census of the organisms present in 
the different foci could not be directly ire pated? in terms of rela- 
tive importance. None of the parasites so far used in inoculation 
have been vigorously parasitic under all conditions. Of both Corti- 
cium vagum and Pythium debaryanum some strains, microscopically 
indistinguishable from the others, are very weak as parasites. Only 
part of the Fusarium species are parasitic on pine, and data showing 
which are and which are not parasitic are known for only a very 
few. There is therefore no fungus which can be said positively to 
be the cause of any particular damping-off “ patch” simply because 
it was found in some of the dead seedlings in the patch. In an occa- 
sional exceptional case, such as the large Corticium patch in figures 
7 and 8, there is such a vigorous growth of the fungus that its pre- 
_ dominance is undoubted, but such cases are rather rare. A census 
throws light on the.importance of the different fungi, but can be 
interpreted only in the hight of inoculation results. 

For Pythium and Geer the inoculation data do not permit | 
any simple comparison between the two, for the reason that neither 
is uniform. Each has strains of high virulence and strains having 
practically no effect on pines. In the inoculations in autoclaved soil at 
sowing time the strongest strains of Corticitwm vagum have on the 
whole caused more damage than any of the Pythium strains, but, on 
the other hand, there has seemed to be a higher proportion of very 


70 BULLETIN 934, U. S. DEPARTMENT OF AGRICULTURE, 


weak strains of C. vagum than in the case of Pythium. In inocula-— 
tions on Pinus banksiana and P. ponderosa in Kansas sand treated 
with acid followed by lime, the average Corticium was very much 
more destructive than even the strongest Pythium strains, allowing 
practically no germination in most cases. On the other hand, in ex- 
periments in which the inoculum was applied directly to Pinus 
resinosa and P. ponderosa seedlings, either immediately after germ- 
ination or after the older parts had become resistant, the Pythium 
has been the more effective. The inoculation evidence so far avail- 
able justifies so nearly equal emphasis on the two that it can prac- 
tically be eliminated from the calculations. It is the writer’s opinion 
that the Corticium strains are probably rather less virulent on the 
average than the Pythium strains, but perhaps better able to main- 
tain themselves and spread from one seedling to another in most 
soils. The evidence of Table IX that the Corticium seemed less fre- 
quent in the damping-off foci is more or less counterbalanced by the 
apparent larger size of many of the disease patches which it seems 
to cause in the seed beds. Nearly all the large clean areas such as 
are shown in figures 7 and 8 have been found to contain abundant 
Corticium hyphe. The evidence on the whole seems to indicate a 
very nearly equal importance for the two fungi. The Pythium is 
probably somewhat the more important for the stations at which 
most of the cultures in Table IX were made, but the Corticium has 
received more emphasis from other observers in this country and is 
indicated by the writer’s observations to be more important in the 
western mountains than any other damping- off fungus. 

The inoculation evidence for Pusarium spp., though less complete 
than for Corticium and Pythium, is nevertheless rather helpful in. 
indicating their importance rating. None of those so far tested in 
inoculations at sowing have shown the destructiveness of the aver- 
age strains of Pythium or of the stronger strains of Corticium; while 
this is only in part a test of virulence and in part a test of the — 
ability of the fungus to grow saprophytically in the soils used, the 
indication is that no one Fusarium species is the equal in destructive 
capacity of either Corticitum vagum or Pythium debaryanum. How- 
ever, when all of the Fusarium species which occur in the seed beds 
are considered, the group as a whole may prove quite as important 
or even more important than either of the other two fungi. The data 
already at hand rather definitely indicate considerable importance for 
all three. 


DAMPING-OFF FUNGI AS CAUSES OF ROOT-ROT AND LATE 
DAMPING-OFF. 


As has been already stated, root-rot, often with frequent recovery, 
has been commonly observed in seedlings several weeks old. It has 
been especially common in the vicinity of old damping-off foci in 


DAMPING-OFF IN FOREST NURSERIES. veil 


which Cortictum vagum appeared to be the active parasite, but 
beyond this indication of the causal relation of C. vagum it was not 
known which of the damping-off fungi were able to attack the roots 
of seedlings too old to be killed by damping-off.. To throw light on 
this point, seedlings of Pinus ponderosa and P. resinosa grown in 
autoclaved soil in the greenhouse and approximately 1} months old 
were inoculated with different fungi. There had been a certain 
degree of early damping-off in these pots, but it had apparently 
ceased before the inoculations were made. The inoculum used con- 
sisted of cultures on rice introduced through the drainage holes at 
the bottoms of the pots. The strains of Pythium debaryanum and 
Corticium vagum used were the ones which had given maximum 
results in earlier inoculation experiments at the time of sowing. The 
strain of Fusarium ventricosum was the only one available, and the 
Fusartum moniliforme strains were all of approximately equal viru- 
lence, the three used having given as much evidence of parasitism 
as any of the strains of this species in the earlier damping-off experi- 
ments. Three pots of each pine were inoculated with each strain. 
Two 3-pot units of each pine were set aside as controls and inoculated 
with sterile rice. In addition, three pots of each pine were kept in 
the same bench without the addition of any inoculum, for comparison 
with the controls with rice. The results of this experiment, taken 
~a month after the inoculations were made, with the seedlings averag- 
ing 24 months old, appear in Table X. The roots of the living seed- 
lings were washed out carefully with water to permit examination. 
The results in so far as they indicate root-rot of the oldest seedlings 
are best shown by the figures in columns 4 and 5. These seedlings 
were so far advanced that the fungi had not been able to kill them, 
and nearly all would probably have recovered if they had not been 
dug up. It will be noted from column 4 of Table X that a consider- 
able portion of the Pinus ponderosa seedlings with root-rot had al- 
ready made their recovery apparent by pushing out adventitious 
roots above the decayed portion at the time they were examined. 
For Fusarium ventricosum there was only the merest indication of 
ability to attack pine roots at this stage. For F. moniliforme the 
evidence is somewhat better, more pots being included and the dif- 
ference in healthy-topped seedlings with injured roots between the 
inoculated pots and the controls being approximately twice its indi- 
cated probable error for each species. The percentage of root-injured 
seedlings in the Pythium debaryanum pots exceeded that in the con- — 
trols in each species by between three and four times the probable 
error of the difference, while the difference in percentage between 
the Corticitum vagum pots and the controls is approximately four 
times its probable error in the case of Pinus ponderosa and five and 
one-half times its probable error in the Pinus resinosa pots. The 


72 BULLETIN 934, U. S. DEPARTMENT OF AGRICULTURE. 


weak point in the results is, of course, the insufficiency of the 6-pot 
and 9-pot groups as bases for probable-error determination. The 

indicated relative ability of these different fungi to cause root-rot | 
is about the same as their relative ability to cause the damping-off of 
sprouting seed and young seedlings, as indicated by the results of the 
earlier experiments in which inoculations were made at the time of 
sowing. The fact that only the very strongest available strains were 
used and that the pots were rather heavily inoculated is to be kept 
in mind in considering these results. As in the seedlings examined 
in the nursery beds, when a root system was partly rotted it was 
only the younger portions of the roots that were affected. The evi- 
dence obtained from this experiment needs to be amplified by experi- 
ments with other coniferous hosts, other strains of the fungi, and 
under other conditions. The experiment just described furnishes 
the only evidence available on the relation of the important fungi 
Pythiuim debaryanum and Corticium vagum to the root-rot of conifers 
and is therefore presented as a preliminary contribution. pia 


TABLE X.—Results of root inoculations of older pine seedlings with damping-off 


fungt. 
ae Seedlings which developed root-rot 
Number of (per cent). 
Tops still healthy. 


Host and inoculating fungus. 
Pots.| Seed- | Rootrecovery. Average | Killed.| Total. 


lings. oftn 
N dividual 
ots. 
Started. |sarted.| P ts 
1 2 3 4 5 6 7 8 
Pinus ponderosa: 

Pythium debaryanum, strains 295, 550, 9 71 27 °25 | 5344.5 4 56 

and 810.@ 
Se ae vagum, strains 147, 213, and 9 56 16 34 | 5143.5 4 54 

747.a 
Fusarium moniliforme, strains 249, 251, 9 64 19 27 | 4246.2 0 45 

and 260.0 
Pgsariiim VenthicCosnim....2 sae nee ee 3 18 ili 39 | 50 0 56° 
Controls. 33h. Suave hk ee ee eee 6 41 2 15 | 2246.5 0 17 
Controls without ric@s. once eee eee eee 3 18 0 17 |. 23 0 17 

Pinus resinosa: 
Pythium debaryantiine.s.--..-aceate sees 9 140 3 16] 1844.0 12 31 
Corticium ‘vagumla.o.- os Seecet eee ee eer ee 9 146 3 16} 2142.4 13 33 
Rusarium moniliforme: 2. o2.625-es5- se 8 128 0 11 | 1243.7 2 13 
Husaritim:ventricosuli,.«- 224s) eee eee 3 39 0 5 4 0 5 
Controls 2.362 wae oe se eee ee eee 6 115 0 3 442.0 6 10 
3 51 0 2 2 


Controls withoutricé: 222040. e- ee eee ee 


a Forrelative virulence of these strains on younger seedlings as compared with other strains of the same 
species, note their position in figures 11 and 14. 
j : zon performance of these strains in inoculations at time of sowing, see an earlier publication (68, 
able 2). 

.The figures in column 7 give information as to the percentage of 
late damping-off resulting from the inoculations. A certain per- 


centage of the early type of damping-off appeared in some of the 


DAMPING-OFF IN FOREST NURSERIES, 73 


- pots, as there were still present a number of soft-stemmed seedlings 
from seeds which were slow in germinating. These younger seed- 
lings were excluded in counting the dead, the rule being to include 
only plants which had developed a sufficiently rigid stem to remain 
upright after death. Comparison of the percentage of killed with 
the total percentage attacked for the two pines is rather interesting. 
As has already been pointed out, while Pinus resinosa suffers very 
heavy damping-off losses at a number of nurseries it seems to be 
‘less susceptible than some other species to parasitic Injury during 
the sprouting period, before the seedlings appear above the soil sur- 
face. Observation of beds of this species during different seasons 
has indicated that it has not a greater susceptibility, but rather the 
fact that its susceptibility lasts longer, which causes it to suffer as 
seriously as it does at certain nurseries. It is indicated in Table X 
that the succulent root tips of Pinus ponderosa are just as easily 
attacked by damping-off parasites as those of P. resinosa—in fact, 
considerably more easily attacked, as indicated by the figures in col- 
umn 8. With the P. ponderosa seedlings, however, the older parts 
of the roots had become resistant at this age in nearly all cases, while 
of the affected P. resinosa seedlings more than one-third were still 
unable to limit the lesions, and death resulted. 

In general, this experiment indicates that Corticium vagum and 
Pythium debaryanum are able to cause the death of some pine seed- 
lings which have developed rigid stems and that both are also able, 
as has been found by other workers in the case of sugar beets, to 
cause “root sickness,” the rot of the younger portions of the root 
systems, in seedlings which have developed too much resistance to 
be killed. The evidence for the parasitism of the two Fusarium 
species ‘on these older root systems is not so good; as in the experi- 
ments on younger seedlings, their ability to attack the pines is prob- 
ably less than that of the other two fungi. Further inoculation ex- 
periments are desirable both with these fungi and with others on the 
roots of seedlings too old to succumb to the more ordinary types of 
damping-off. 


RELATION OF ENVIRONMENTAL FACTORS TO DAMPING-OFF. 


In the earlier section dealing with disease control, mention was 
made of the general belief on the part of men who have had experi- 
ence with seedling diseases that damping-off is favored by thick seed- 
ing, by much organic matter, especially by poorly rotted manure in 
the soil, and by excessive moisture in the air and soil. It is also 
commonly stated that high temperature favors the disease; on this 
point there is perhaps a less general agreement. Practically all the 
evidence on these points is observational. 


74 BULLETIN 934, U. S. DEPARTMENT OF AGRICULTURE, 
DENSITY OF SOWING. 


The relation between the disease and thick sowing was strikingly 
indicated for tobacco seedlings in a single experiment by Johnson 
(82). For pines the only available information is from four experi- 
ments on Pinus banksiana. 'The results of the first two appear in 
figure 19. In both experiments there is an indication of an increase 
in the percentage of diseased plants as the seed derisity is increased. 
There is, however, no such marked relation as in Johnson’s work. 
As the pines were sown in drills, they were so close together even in 
the less dense plats that no very great increase in the ease of spread 
of the disease was to 
be expected from in- 
creasing the density. 
Greater differences 
should be expected 
in broadcast beds. 
That heavier losses 
have been found in 
drill-sown beds than 
in those sown broad- 
cast (69, 189) is pre- 
sumably explained 
by the fact that with 
NUMBER OF SEEDS SOWN pip SQUARE FOOT OF BED equal 2a 
Fig. 19.—Diagram showing the extent of damping-off in seed et ee foot 
drill-sown Pinus banksiana in plats with different seed of seed bed the seed- 
densities. The regular seed density at this nursery was lings are much closer 


600 seeds per square foot. together in drile 
than in broadcast beds, and thus the spread of the mycelium of para- 
sites from one seedling to another is facilitated. : 

Two tests of different seed densities were also made in 8-inch pots 
of autoclaved soil in the greenhouse. Each regular pot was sown 
with 28 seeds (equivalent to 600 per square foot). The pots were 
inoculated by adding to each a single small fragment of an agar 
culture of Pythtum debaryanum. Uninoculated pots showed an emer- 
gence of approximately 50 per cent of the seed and were entirely free 
from subsequent damping-off in both experiments. The results ap- 

pear in Table XI. 

In this case not only the damping-off after emergence but the loss 
before the seedlings appeared bore an apparent relation to sowing 
density. In the field experiments there was no evidence that the loss 
before the seedlings appeared was affected by seed density. 


100 


pene 


PERCENTAGE OF SEEOLINGS OAMPED-OF F 
PFTER GERMINATION. 


DAMPING-OFF IN FOREST NURSERIES. 75 


TABLE XI.—Results of inoculation, at the time of sowing, with Pythiwn 
debaryanum on Pinus banksiana in different sowing densities in pots of 
autoclaved soil. 


[The percentages of “‘ Damping-off,’’ columns 4and 7, are based on the number of peediines, the percentages 
ziven in columns 3, 5,6, and 8 are based on the number of seeds.] 


Num- Results (per cent). 
ber 
¢ of E : 
Density of seed sowing. poe Experiment 58. Experiment 59. 
ex- 
peri- Damp-| Sur- Damp-| Sur- 
ment. Emerged. ing-of. vival. Emerged. ineeans vival. 
1 2 3 4 5 6 7 8 
POT i rr rr 10 15 43 10 26 13 23 
eS ee 5 8 65 3 8 91 1 
DOL... 3404. eo 5 1 100 0 11 34 7 
Regular, but 10 additional coeds near 


pomtrofimoculation:--....-..-..2-.:..-2 5 6 33 4 17 37 11 


MOISTURE AND TEMPERATURE FACTORS. 


The relation of damping-off to moisture and temperature are sub- 
jects less easily studied» In 1907 and 1908 Mr. W. H. Mast, then 
supervisor of the Nebraska National Forest, conducted daily counts 
of the number of seedlings damped-off and compared these records 
with temperature and rainfall records. The writer in 1909 repeated 
his work, maintaining parallel records of damping-off, air and soil 
temperatures, soil moisture, atmospheric humidity, wind movements, 
and evaporation. The 1909 records of damping-off, temperature, 
soil moisture, and evaporation appear in figure 20. The damped-off 
seedlings were counted and removed in the morning and evening, the 
day period thus being in most cases 10 to 11 hours and the night 
period 13 to 14 hours. Because the period was not always the same 
length, the data are reduced to a per hour basis. Air temperature 
was recorded by a sheltered thermograph 3 feet above the soil sur- 
face. ‘The evaporation graph represents the mean loss per hour 
from two porous cup atometers of the writer’s own design, in which 
the rather long and slender Chamberlain filter bougie was used and 
supported in a horizontal position just above the soil surface so as 
to be under as nearly as possible the same atmospheric conditions as 
the seedlings. The two bougies were placed at right angles to each 
other in order to eliminate as far as possible the effect of change of 
wind direction on their mean loss. While the rain-correction mount- 
ing had not at that time come into use, the error due to rain absorp- 
tion appeared negligible; atometers filled shortly before rainfall 
were read immediately after without any gain being found in the 
water in the reservoir. The psychrograph and wind-movement rec- 
ords are not presented, as the evaporation values are more easily inter- 
preted. Soil moisture was periodically determined in the soil of the 


‘md ¢ 0} GZ Jo qJdop ye— X “UD GZ 01 C JO FIdep J2—© “Ud 9°90 01 C Jo FIdep IV¥—= @ J OANYSTOUT [TOS 0} SULIJojJoI sjoquids Jo uoljeurldxg” 
‘WH "8 0O'Y O8}VOTPUT SOUT] [BOT}1OA OY} ‘SP1OIII VINJS[OUI-[IOS PUB BIN} VIOdUI9} 94} JOY ‘VdVJANS [[OS oY} MOTEG “WO |g paTINqd SBM q[Nq ssOyM AeJOMIOW 
-I0Y} B JO SSUTPVIT 9}VOTPUT VAIND STG} SuTAUVduUI0IIV S}Op 94} 9TIYA ‘Spoq Vy} JO VdVJANS OY} BAOGL JojJOM J YdvASouIAey} pozd}peys BV WOAJ UAV} ST 9AINO 
aIn}ei1edule} eUT, ‘sIseq A[INOY UB OJUL pdjJ1OAMOD o1B SoINSY osey} ‘YISue, [ends JO JOU o1VM POPTAIP Sng} SVM OTT} 9Y} YOM ojUT Sporied (N) 2qSIU 
pue (q) Avp 04} SY ‘“SUTUIOU puv }YSIU ‘peJUNOD SSUT[pses P¥vEp 24} PUB PoINSveM SVA SJoJoMIOUT}e And-snoiod wWOIJ UOT BIOdvAS OT], *SUOTJIPUOD 
21N}VIOAUIO} PUB IIN}JSTOUL 9G} SUI} BOIPUL puv VYSBVIqEN Ul Alesinu B Je DUDISYyUDg sNUWL_ JO Speq UI Yo-Surduep jo sseiSo01d ey} Surmoys WBISVIG—'0Z ‘DIT 


9 2 smpoe 62 82 22 92 982 Be C2 22 42 Of 6 BI 9/ o/ 6 6GtCel uN o/- @ INN 
NGNOENONEMNONONGNINDNGNGNOMONEDMONONINONGN ONONGNON GNOME 


LTT AN 
LNAI NANA 
Wy a Lene 


ae ast o/ 
NUNZGWN 


r 


ds 
Oy i ee 
S$ ¢ ee 


+ 
fe} 

(1N39 43d) YNOH HId 

-OIASWLO SONITAZ. 


“NOH HIS JI 


MLSIOW 08 FUNLYATAINIL NO/LYAOSL/F 


BULLETIN 934, U. S. DEPARTMENT OF AGRICULTURE. 


ll 
alti 
i 


O02 
S$ 
se 
q 2 lll ee oe 
*. i +o Le ol 
Mp t ‘ : N 
of. fl * | xt ‘\e) o2 8 
Nei | & 
oe = 
== 
™m 


76 


DAMPING-OFF IN FOREST NURSERIES. ar 


plats on which the seedling counts were conducted, each determina- 
tion representing two, and in some cases four, points. The deter- 
minations for the upper one-fourth inch of soil, made more frequently 
than for lower levels, are connected in figure 20 by a dotted line, 
which gives some idea of the amount of moisture in the surface soil 
during the periods between determinations. The determinations were 
too infrequent to permit anything more than an estimate of the 
moisture conditions between determinations, but the writer, having 
before him the records of the times and amounts of rainfall and 
artificial watering as well as the evaporation and soil-moisture de- 
terminations, is in a better position to make such an estimate than 
the reader. The dotted line which gives this estimate should not be 
depended on to show what the percentage of moisture was at any one 
time, but is believed reasonably reliable as showing whether in gen- 
eral the soil was wet or dry. In interpreting the soil-moisture rec- 
ords, it should be kept in mind that the soil was very sandy, the 
wilting coefficient of composite samples from various parts of the 
- nursery, as determined by the indirect method of Briggs and Shantz 
in the Laboratory of Biophysical Investigations of the Bureau of. 
Plant Industry, being only 3.4 per cent. The hygroscopic moisture 
in dry air for the soil of the plats actually under consideration was 
indicated by repeated determinations for the surface soil on dry days 
to be in the neighborhood .of or slightly below 2 per cent. The 
nursery is located in a region of large temperature fluctuations, where 
the air during the day is generally dry, and consequently the dew 
is heavy at night. 

The first result of interest is the difference between the damping- 
off for the day and the night periods. In the records of every 
day but two, more seedlings went down during the day period than 
during the night, the differences in most cases being large. As the 
evaporation and temperature showed similar day and night- fluctua- 
tions, it is difficult to say whether temperature or moisture condi- 
tions were responsible. The other interesting result brought out by 
the graphs is the sudden drop in the general level of the damping- 
off graph following the rains of June 15, June 19-20, and July 3. 
In each of these three cases the damping-off came up again only 
after the soil moisture came down. 

The fact that in the daily fluctuations the damping-off varied 
directly with the evaporation rather than inversely is an apparent 
contradiction of the generally accepted doctrine that moisture favors 
the disease. This contradiction is, however, only apparent. Dur- 
‘ing the first part of the damping-off period, when the seedlings are 
still soft, the recognition of damping-off depends on the decay of 
that part of the stem just above the soil surface which allows the 
seedling to fall over. This usually takes place at this nursery as 


78 BULLETIN 934, U. S. DEPARTMENT OF AGRICULTURE. 


a result of the extension upward of lesions which have started on 
the parts a little below the soil surface. It is supposed that such — 
decay takes place most rapidly at high temperatures and that it is 
the temperature rather than the evaporation graph which the damp- 
ing-off is following in these early day and night fluctuations. Dur- 
ing the latter part of the damping-off period a dying seedling shows — 
its first signs of distress in the drying up of its leaves, the stem being 
too stiff to go down until after the infection has gone far enough 
in the roots to cut off most of the water supply. It is, of course, 
under dry conditions that such a sign of distress will be most in 
evidence. During the latter part of the damping-off period it is 
therefore altogether likely that the day and night fluctuations are 
caused, at least in part, by the higher evaporation rate which ob- © 
tains during the day. This is a relation not to the rate of progress 
of the disease, but rather to the rate at which the symptoms of dis- 
ease appear in plants already seriously aff ected. | 

The drop in damping-off following the increased soil moisture of | 
June 15, 19-20, and July 3 also apparently contradicts established 
doctrine. While it is ordinarily true that a wet soil is a cold soil 
and that in the rainy weather which causes wet soil the evaporation 
is usually low, it does not seem possible on inspection of the graphs 
for these items to attribute entirely the reduction of damping-off 
during these periods of wet soil either to low temperature or to low 
evaporating power of the air. Lowered soil temperature probably 
had something to do with the reduced loss following the rains. It 
is also suggested that a sudden change in moisture content may tem- 
porarily hinder a soil fungus by decreasing its air supply. In this 
sandy soil the fungi can work at very considerable depths during 
dry periods. Initial lesions have been found as much as 12 inches 
below the surface. If this soil is as completely changed in its aera- 
tion qualities by wetting as the sandy soil with which Buckingham 
(19) worked, a rain might result in a rather sudden change in the level 
‘at which the fungus is able to operate. . 

On the whole, the graphs tend to confirm the common statement 
that high temperature favors damping-off. It must, however, be 
borne in mind that in uncontrolled field plats several factors vary 
simultaneously, and it is impossible to definitely attribute any ob- 
served phenomenon to any one of them. Furthermore, it is not 
possible to say for the seedlings at different ages just how long it will > 
take a factor to exert an effect on the damping-off curve. An addi- 
tional consideration is that a method of investigation which gives 
entirely: reliable information on the speed with which the disease 
develops does not necessarily throw light on the conditions under 
which the greatest total amount of disease can be expected before 
the seedlings become old enough to resist attack. High temperatures, 


DAMPING-OFF IN FOREST NURSERIES. 79 


within reasonable limits, are expected to increase the speed with 
which the disease works, but these should also hasten the develop- 
ment of the host to a point at which infections are unable to cause 
death. It is the total amount of damage in the beds rather than the 
damage per unit of time which is of practical importance. For a 
number of reasons, then, the method followed in obtaining the data 
for these graphs can not give information of maximum value. While 
data of the sort mentioned are of undoubted interest and would be 
of still more value if the records had been commenced when the first 
seedlings appeared instead of a few days later, the relation of any 
specific factor to the total extent of the disease can be better deter- 
mined by comparing plats in series in which the factors are as far 
as possible controlled and varied one at a time. To vary soil moisture 
and soil temperature independently will prove somewhat difficult, 
but it can be done with the proper facilities. ‘Some work with en- 
vironmental factors should be done under conditions of artificial in- 
oculation in the greenhouse, in which the different damping-off 
parasites can be experimented with separately, as it is obvious that 
the factors which favor the activity of one may not be favorable for 


another. 
CHEMICAL FACTORS. 


Chemical factors are presumably also important, as the soil is 
in most cases the culture medium for both the parasite and the host. 
The much greater activity of Pythiwm debaryanum in autoclaved 
soil than in untreated soil may be due to the larger quantity of 
soluble organic matter commonly present in autoclaved soil. Pythium 
debaryanum has been found more sensitive to unfavorable substrata 
in artificial culture than Corticitwum vagum and is apparently more 
dependent on soil organic matter in the nurseries than is C. vagum. 
For example, in the normal humus-containing surface sand in the 
beds at Cass Lake, Minn., both Pythium and Corticium occurred 
frequently in the damped-off seedlings, while in beds a few feet 
distant, from which enough of the surface soil had been removed to 
leave no humus, nearly all the damping-off foci contained abundant 
Corticium, and no Pythium could be found. With both fungi and, 
in addition, with two species of Fusarium (68) heavy inoculation has 
been more successful in experiments at the time of sowing than 
light inoculation. This has been thought possibly due in part to the 
larger amount of nutrient substratum added in the heavy inocula- 
_ tions, allowing better saprophytic development of the fungus in the 
soil. In each of the two experiments with Pythium reported in 
Table XI, a 5-pot unit was treated with corn-meal infusion and 
another with prune infusion at the time of inoculation. In both 
experiments germination was lower, damping-off after germination 
higher, and the survival less than half as great in the pots with 


80 BULLETIN 934, U. S. DEPARTMENT OF AGRICULTURE. 


infusion as in the inoculated pots not so treated. In the first experi- 
ment 5-pot units of unheated soil were also inoculated in the same 
way. In these also both the units which received infusions showed 
less germination and more loss after germination than the unit which 
received no infusion, though the differences were smaller than in the 
autoclaved soil. In the second experiment the light inoculation used 
failed to cause material loss in the unheated soil units, even though 
two of them were treated with the infusion as in the previous test 
and two others received triple portions of the infusion. 

The experience in the nurseries, in which heavy applications of 
manure, and especially poorly ranbed manure, in a number of cases 
have apparently resulted-in increased disease, and the finding of 
Fred (43) that green manures recently plowed under favored the 
work of Corticium have already been mentioned. The addition of 
dried blood at two nurseries in Kansas was in both cases followed 
by very much heavier loss than in the controlled plats. The-only 
instances known to the writer in which the addition of organic 
matter to the soil has shown any indication of materially decreasing 
damping-off (with the exception, of course, of the organic disin- 
fectants) are the result reported by Gifford (46) with tankage, a 
single case in the writer’s experience with bone meal, and the cases 
in which cane sugar has seemed to decrease losses somewhat (67). 
It is of some interest to note that the experience available also indi- 
cates increased disease as a result of the addition of inorganic nitrog- 
enous substances. Sodium nitrate and sodium nitrite have both 
given some indication of increasing damping-off. Ammonium sul- 
phate in six separate series has in every case resulted in decreased 
stands, though unfortunately in experiments in which the damped- 
off seedlings were not counted. Ammonium hydroxid, though ap- 
parently having some initial value as a disinfectant, as indicated by 
early damping-off losses, in a number of cases has been followed by 
very heavy total losses. This experience is of some interest in view 
of the apparently rather general belief that plants on a soil a 
in nitrogen are especially susceptible to disease. 

The ene factor for which there is perhaps the most evidence 
of a relation to damping-off of conifers is acidity. The fact that 
sulphuric-acid soil treatment has been found to be one of the most 
effective means.of controlling the disease, that its value is mainly. 
lost if lime is later added to the soil, that soil treatment with sulphur 
in a number of cases has seemed to decrease the disease, and that 
lime alone and wood ashes have had either no effect or have appar- 
ently increased the damping-off whenever they have been tried, all 
suggest that soil acidity is not favorable to the disease. Additional 
indication of this appears in figure 12. The acidity determinations 
serving as the basis for the graph were made by Dr. L. J. Gillespie, 


DAMPING-OFF IN FOREST NURSERIES. 81 


of the Bureau of Plant Industry. The estimates of the relative se- 
riousness of damping-off are very approximate, based in part on 
observation only. The stations at which damping-off is rated as 1 
are places at which it has been reported by nurserymen or foresters 
as negligible or absent. The estimates for stations 10, 11, 14, and 15 
are based entirely on the reports of others, and for station 5 on the 
basis of counts of damped-off seedlings made by Mr. R. G. Pierce 
and Mr. Glenn G. Hahn. The writer personally has made the esti- 
mates or checked the estimates of the nurserymen at the other sta- 
tions. A considerable degree of correlation between the hydrogen- 
ion exponent and the amount of damping-off appears on the face 
of the graphs, the coefficient being 0.75+0.07. If the correlation is 
calculated with the H* concentration itself instead of its negative 
exponent, the coefficient, in this case itself negative, is not so high 
(—0.58+0.11). All of the above data on acidity relation have been 
picked up incidentally in connection with other work and are merely 
suggestive. The suggestion, however, seems sufficiently strong to 
warrant further experimental work directed specifically at the rela- 
tion between soil acidity and the disease. 

The indication in the graph that damping-off is not serious in 
soils in which the hydrogen-ion exponent (P,)° is less than 6 is of 
particular interest, in view of the experience of Hawkins and Har- 
vey (71) with cultures of Pythium debaryanum on potato juice. 
They obtained good growth through a range of acidity from Py 3.4 
to 5.8, with no growth or practically none at 3.06 or 8.4. If this 
represents the acid tolerance of the fungus in the soil solution, it is 
evident that ordinarily acid soils can not be expected to remain free 
from damping-off because of inhibition of this particular fungus. 
This suggests that the apparently salutary influence of soil acidity 
in decreasing the damping-off of some of the conifers may be ex- 
erted in the direction of increasing the resistance of the host rather 
than of inhibiting the parasites. In any case, it must be kept in 
mind that as the numerous conifer hosts commonly grown in nurseries 
have many different habitat preferences and many very different 
parasites of potential importance, it is not to be expected that there 
will be found any such constant relation between any factor and the 
amount of disease as would be expected in a disease in which only a 
single parasite and a single host are involved. 


6Pu 6 is equivalent to a hydrogen-ion concentration, expressed in mols per liter, of 
1X10-* or 0.000001. The higher the exponent, the smaller the hydrogen-ion concentra- 
tion. An exponent of 7 means approximate neutrality. In dealing with this exponen- 
tial form of expression, it should be kept in mind that Ps6 means ten times and Px5 
one hundred times the hydrogen-iron concentration indicated by Pu7. Conversely, the 
concentration of hydroxyl-ions at Pu7 is one hundred times as great as at Pad. 


19651°—Bull. 934-216 


82 BULLETIN 934, U. S. DEPARTMENT OF AGRICULTURE. 


BIOLOGIC FACTORS. 


Mention has already been made of two strictly biologic factors — 
which may influence the amount of damping-off. Taylor (138) and 
Rathbun (106) have found Fusarium not only at considerable depths 
in the soil of pine seed beds, but viable Fusarium spores without 
hyphe in the alimentary canals of earthworms and insect larve in 
the soil, and they attribute to the migrations of these and to the 
tunnels which various animal forms make in the soil a possible im- 
portance in the distribution of damping-off Fusaria. A likely rela- 
tion between Cortictum vagwm epidemics in pine seed beds and the 
character of the weed flora has also been considered (66). 

The relation between the damping-off parasites and other micro- 
organisms in the soil is also a matter of some interest. The effect of 
the microfauna of the soil on the microflora in general has been 
considered by Russell and others in a number of papers. The effect 
of soil disinfection by heat in favoring the work of artificially intro- 
duced soil-inhabiting fungous parasites, apparently a rather frequent 
phenomenon and quite evident in the inoculation experiments with 
Pythium debaryanum reported in the present bulletin, has been in 
other cases attributed to the removal of bacteria and other fungi 
which might compete with the parasites (36, 80). Heating soil is 
known to produce physical changes and also very considerable chemi- 
cal changes both in organic and inorganic substances. These must not 
be ignored in considering the effect of previous soil heating on para- 
site activity. With a view to determining whether all the difference 
noted in the behavior of P. debaryanum in heated soil is due to the 
direct effects of the heating or in part to the elimination of com- 
peting microorganisms, an experiment was conducted in 3-inch pots 
of autoclaved soil in which 111 of them were inoculated with agar 
cultures of the Pythium at one point in each pot shortly after seed 
sowing. The seeds sown in each pot approximated 136, considerably 
more than are used on equal areas of nursery seed bed. Of these, — 
fifteen 5-pot units and one 3-pot unit had been inoculated broadcast 
with rice or nutrient agar cultures of various organisms supposed to 
be saprophytic on pines. These included Phoma betae, Phoma sp., 
Chaetomium sp. (from a maple root), Rhizopus nigricans, Tricho- 
thecium roseum, Trichoderma koningi, Aspergillus spp. (including 
one with black and one with bright-colored spore heads), Rosellinia 
sp. (from soil), Penicillium sp., an undetermined bacterium, and three 
undetermined higher fungi. The whole 78 pots inoculated with P. 
debaryanum and saprophytes, the percentages being based on the 
total number of seeds in the case of emergence and survival and on 
the number of seedlings which appeared above ground for damping- 
off loss, as compared with those which had received the parasite only, 
gave results as follows: 


DAMPING-OFF IN FOREST NURSERIES. . 83 


Pots with saprophytes: Emergence, 47.40.86 per cent; damping-off, 9.1 per 

cent; Survival, 41.0+1.28 per cent. 

Pots without saprophytes: Emergence, 35.7 per cent; damping-off, 14.3 per 

cent; survival, 29.2 per cent. 

It has been noted in the attempts to diagnose damping-off by 
planted-plate cultures that when Rhizopus appears Pythium debary- 
anum is not frequently obtained. It is therefore of some interest to 

note that in this case, in the two 5-pot units which received Rhizopus 
in addition, the parasite killed only 1.2 per cent and 3.3 per cent, 
respectively, of the seedlings which appeared above the soil. 

At the same time pots not inoculated with parasites were sown, 16 
other 5-pot units were inoculated with the same saprophytes as those 
used in the Pythium inoculated’ pots, while 25 pots were left entirely 
without inoculation. A certain amount of damping-off occurred in 
these pots also as a result of accidental infection. The results were 
as follows: 

Pots with saprophytes: Emergence, 47.8+0.8 per cent; damping-off, 3.9 per 

cent; survival, 48.70.95 per cent. 

Pots without saprophytes: Emergence, 43.0 per cent; damping-off, 5.2 per 

cent ; survival, 38.4 per cent. 

It is of some interest to note that in these pots also the 5-pot units 
inoculated with Rhizopus suffered less from damping-off than the 
average of the saprophyte-inoculated pots. ° 

The probable-error values given above are based on the variability — 
of the emergence and survival figures of the different 5-pot units. 
No individual figures are available to serve as a basis for the deter- 
mination of the variability of the pots without saprophytes. The 
16 units which support the error determinations are, of course, not a 
sufficient number to give an entirely reliable index of variability, 
though these 16 units are respectively derived from the combination 
of a total of 78 and 80 ultimate units. The distribution of the data 

appears to be such as to justify the use of probability methods. Of 
the 64 items which went into the germination and survival calcula- 
tions, 34 showed a deviation equal to E, (probable error of a single 
unit), 9 to a deviation equal to 2E,, and only one a deviation equal 
to 3K. : 

All of the above figures are based on the results at the end of 10 
days after average emergence in the pots. The pots were kept on the 
benches till practically all damping-off had ceased, 36 days after 
emergence. As additional accidental infection with saprophytes 
certainly, and probably with parasites, occurred during this period, 
the results at the end of the tenth day are considered to give a better 
indication of the effect of the original inoculations. It is of some 
interest, however, to note that during the period from the tenth to 
the thirty-sixth day the difference between the pots to which sapro- 


84 BULLETIN 934, U. S. DEPARTMENT OF AGRICULTURE. 


phytes had been added and those which received no saprophytes 
showed a slight increase, proportionally as well as in the absolute 
figures. At the end of the 36 days the survivals on all the pots were 
counted separately. The average number of seedlings per pot were 
as follows: . 
Without Pythium: 
Without saprophytes, 42.82.38; with saprophytes, 52.1£1.1 
With Pythium: 
Without saprophytes, 30.1£2.4; with saprophytes, 48.1+1.4. 

The difference in the survivals in favor of the pots with sapro- 
phytes in the first case is 9.3+2.5, three and two-thirds times its 
probable error. In the second case it is 18.0+2.8, more than six times 
its probable error. 

In general, it appears that in this experiment the inoculation of ster- 
ilized soil with saprophytes gave the seedlings some protection both 
against damping-off due to accidental infection with unidentified 
parasites and: from the additional loss caused by light inoculation 
with Pythiuwm debaryanum. ‘The indication is, as would be expected, 
that only part of the favoring influence of heat sterilization of soil 
on introduced P. debaryanum is immediately due to the elimination 
of competition with other fungi. If a mixture of different bacteria 
and fungi had been added to each of the pots instead of but one or 
_ two organisms to each 5-pot unit, the effect might have been more, 
marked. 

It will be noted that for all the groups (fig. 18), whether with or 
without Pythium inoculation and with or without added parasites, 
the frequency polygon is asymmetrical, indicating by its shape, as 
did the frequency polygon of survivals in pots inoculated with Rheo- 
sporangium (fig. 17), that with infections which do not kill all of 
the seedlings the selection tends to be by pots rather than by seed- 


lings. In other words, in pots in which the parasites succeed in kill- . 


ing any of the seedlings, they usually kill a considerable number. 
The tendency is illustrated not only by inspection of the graphs, but 
by the variability of the different groups. The greater variability 
in survivals between different pots was in both cases in the groups in 
which both the damping-off after emergence and the survival per- 
centages indicated the largest loss. The percentages of seedlings 
damped-off during the entire 36 days following emergence and the 
coefficients of variability of the survivals of the individual pots at 
the end of that time are as follows: 
Without Pythium: 
Without saprophytes, 15.5 per cent damped-off; coefficient of variability, 
3944.2 per cent. : 
With saprophytes, 11.1 per cent damped-off; coefficient of variability, 
281.6 per cent. - 


a 


= | = 


¥ 


/ 


DAMPING-OFF IN FOREST NURSERIES. 85 


With Pythium: 

Without saprophytes, 27.5 per cent damped-off; coefficient of variability, 
677.8 per cent. 

With saprophytes, 16.9 per cent damped-off; coefficient of variability, 
392.4 per cent. 

This tendency has been frequently observed in experiments in 
which inoculum is applied to the soil at the time of sowing. Even 
in experiments in which a relatively small proportion of the seed- 
lings are killed, some of the pots are nearly or entirely cleaned out. 
It is taken as an indication that failure of inoculation to give results 
is often due to the inability of the fungus to maintain itself in a 
vigorous condition till the germinating seed is far enough along to 
allow easy infection. It may also be in part due to lack of uni- 
formity of the soil in different pots affecting virulence of parasites 
or resistance of hosts. 

In addition to this experiment on speed soil, a somewhat 
similar experiment was conducted in a nursery in the Kansas sand 
hills on soil which had been treated with sulphuric acid, followed 
by lime raked into the soil. Saprophytes, for the most part the 
same strains that had been used in the experiment in the greenhouse, 


were added to 24 plats, each of one-half square foot, of Pinus bank- 


siana and 24 of P. ponderosa, with 16 interspersed plats of each 
species serving as controls. The saprophytes were growing on rice, 
part of which was added to the plat with the inoculum in addition 
to the fungous mycelium. .Damping-off was rather heavy in this soil 
from accidental infection or from parasites which survived the 
initial acid treatment, no parasites having been artificially intro- 
duced. The loss was probably due to Corticium vagum or Fusarium 
spp. rather than to Pythium debaryanum in this case. In both pines, 
emergence was slightly better in the control plats than in those to 
which the saprophytes had been added, the difference for Pinus bank- 
seana being less than half its probable error and for P. ponderosa 
shghtly more than its probable error. Damping-off for the first few 
days after emergence was somewhat less in the controls in one species, 
but higher in the saprophyte-inoculated pots in the other. The 
saprophytes therefore gave no evidence of effective competition with 
the parasites on this acid-lime treated sand. 

While the competition for water which seems to Te the form of 
competition most common among green vascular plants is not likely 
to be of significance between fungi such as those which cause damping- 
off, a very little observation of the growth of mixed cultures of the 
parasites and other organisms in Petri dishes is sufficient to make 
one realize that the latter may very considerably decrease the activity 
of certain of the parasites. In nutrient agar most of the fungi and 
bacteria introduced from the soil in attempting parasite isolations, 


86 BULLETIN 934, U, S. DEPARTMENT OF AGRICULTURE. 


as well as to a less extent the paramecia, nematodes, and amcebee 
which develop in such plates, exert a very considerable limiting in- 
fluence on the growth of most of the damping-off fungi. That they 
should also limit the growth of parasites in soil, whether by the 
production of toxic compounds, the exhaustion of food materials, or 
in other ways, seems entirely reasonable. The results in the writer’s 
experiments on heated soil warrant the suggestion that further trials 
should be made of the introduction of vigorously growing bacteria 
or molds, preferably mixed cultures containing a number of different — 
organisms, on seed beds which have been disinfected by some such 
method as steam or hot water, which leaves the soil in a favorable 
condition for the development of accidentally reintroduced parasites. 
If such treatment should be successful in improving the rather dis- 
appointing results with soil heating at some nurseries, it might 
easily become of practical value, as the cultivation of certain of the 
more easily grown saprophytes on a scale large enough to yield con- 
siderable quantities of bacterial or spore suspensions should be fairly 
easy and entirely practicable in an operation as intensive as that of 
raising coniferous seedlings. 


ACKNOWLEDGMENTS. 


The writer wishes to express his obligations to Dr. H. A. Edson, 
of the Bureau of Plant Industry, United States Department of 
Agriculture, and to Prof. W. T. Horne, of the University of Cali- 
fornia, for suggestions during the progress of this work; to Mr. Roy 
G. Pierce and Mr. Glenn G. Hahn, of the Bureau of Plant Industry, 
for assistance in a number of the inoculation experiments; and to 
other members of the staff of the Office of Forest Pathology for 
assistance and suggestions at various times. | 


SUMMARY. 


(1) Damping-off in nurseries is caused mainly by seedling para- 
sites which are not specialized as to host; Pythium debaryanum and 
Corticium vagum are probably the most important of these. Damp- 
ing-off of various herbaceous hosts, including ferns, is often caused 
by specialized parasites which are limited to a particular host or 
group of hosts. Phoma betae is a rather extreme example of such 
specialization. For the conifers all the damping-off appears to be 
due to parasites of the generalized type. 

(2) Damping-off of trees, as of herbaceous plants (with the ex- 
ception of the cases caused = specialized seed-carried parasites), is 
ordinarily serious only in seed beds or cutting beds in which large 
numbers of plants are crowded together in a small space. In most of 
the forest nurseries it is a much more serious matter in conifers than ~ 
in dicotyledonous seedlings. 


DAMPING-OFF IN FOREST NURSERIES. 87 


(3) The most serious losses in conifers are ordinarily from the 

- root-rot type of damping-off, occurring soon after the seedlings 
appear above ground and while the hypocotyls are still soft. Losses 
due to the killing of dormant or sprouting seed by parasites before 
the seedlings appear above the soil are also frequently serious, some- 
times necessarily more so than the later types, as in extreme cases 
more than half of the seed or young seedlings are destroyed in this 
way. Damping-off due to infections of parts above the soil surface 
is serious only under extremely moist atmospheric conditions. The 
late type of damping-off, in which the roots are rotted after the 
stem becomes too rigid to be easily decayed, is ordinarily less im- 
portant than the early types. Seedlings more than 2 months old are 
ordinarily able to recover from infections by the damping-off fungi. 
Even after the first month, seedlings with part 2 their root system 
killed often recover. 

(4) It is possible that damping-off has a certain value as a selec- 
tive agent by eliminating weak individuals in the seed-bed stage and 
allowing only the best trees to go into forest plantations. This 
value, however, is believed to be slight. Disinfectant treatments of 
seed beds, even when controlling early parasitic losses very well, 
allow a considerable percentage of disease during the last part of 
the damping-off period, often as much as occurs at the same stage of 
development in untreated beds. As it is only this late damping-off 
in which differences in individual resistance of the seedlings seem to 
be of importance in determining whether or not they succumb, it is 
believed that whatever selective value the disease may have will 
appear in a larger proportion of the damping-off in the treated than 
in the untreated beds. 

(5) Of the. different conifers, reports are available as to the sus- 
ceptibility of 63 species. Species which are especially susceptible 
at some nurseries may prove more resistant than the average at 
others. Pinus resinosa, which is especially subject to loss at some 
_ nurseries, is believed to be so because its growth at these nurseries is 

slow and its period of susceptibility is therefore especially long. 
Tn its early stages it does not seem especially susceptible. Repre- 
sentatives of all the commonly grown genera of the Abietoidee have 
been reported by one observer or another as decidedly susceptible. 
The reports on junipers and other members of the Cupressoidez, on 
the other hand, have indicated a considerable amount of group re- 
sistance to damping-off. 

(6) The best control method appears to be the disinfectant treat- 
ment of the seed-bed soil before or immediately after seed is sown. 
Sulphuric acid has been found very useful for conifers, as they are 
apparently especially tolerant of acid treatment. No method has yet 
been worked out to a point at which all of its details are entirely 


88 BULLETIN 934, U. S. DEPARTMENT OF AGRICULTURE. 


satisfactory, though the acid treatment has now been in successful 
use for several.years at some nurseries. At most nurseries, if the 
minimum effective quantity of acid is used, there is no need of any 
special precautions to prevent injury to the seedlings. It is not 
expected that any single treatment can be found that can be uni- 
versally applied without change in details irrespective of differences 
in soil characters and in fungous flora. 

(7) Cortictum vagum and Fusarium spp. have been previously 
shown to be parasitic on pine seedlings. Different strains of (0. 
vagum are found to vary considerably in their ability to cause damp- 
ing-off, certain strains being consistently destructive and others 
much less active in tests conducted on different species of pine and 
several years apart. The differences in activity between strains 
were greater, and apparently rather more constant from one ex- 
periment to the next, than with Peltier’s strains in his carnation ex- 
periments. Comparison of the results on pine with those of Edson 
and Shapovaloy on potato gives some indication that strains vigor- 
ously parasitic on one of these hosts are likely to be parasitic on the 
other also. 

(8) Pythium debaryanum, reported on many hosts and proved to 
be parasitic on few, is shown by repeated inoculation, reisolation, 
and reinoculation to be capable of causing the damping-off of seed- 
lings of pine species. The identity of the fungus causing the damp- 
ing-off of conifers with that attacking dicotyledons has been estab- 
lished by cross-inoculations as well as by morphological comparison. 
Inoculations on unheated soil are much less destructive than on 
heated soil. Pythium debaryanum has been obtained in culture from 
Picea engelmanni, P. sitchensis, Tsuga mertensiana, Pinus banksiana, 
P. nigra austriaca, P. ponderosa, P. resinosa, and Pseydotsuga taat- 
folia. In addition, fenugreek (7'rigonella foenum-graecum), cowpea 
(Vigna sp.), and rice (Oryza sativa) are reported as apparently new 
hosts among the dicotyledons. In inoculations the fungus has been 
successfully used on Pinus banksiana, P. ponderosa, P. resinosa, and 
in a preliminary experiment on Pseudotsuga tawxifolia. It had 
already been successfully used in preliminary inoculations on Pacea 
canadensis by Hofmann (77). 

Differences in parasitic activity on pine are found between differ- 
ent strains of Pythiwm debaryanum. These differences are not as 
large and partly for this reason their constancy is not quite as con- 
clusively demonstrated as in the case of the strains of Cortecowm 
vagum. 

(9) Rheosporangium aphanidermatus Edson, a parasite of radish 
and sugar beet, in many ways closely resembling Pythiwm debary- 
anum, has killed seedlings of Pinus banksiana and P. resinosa in 
certain experiments, and reisolations and reinoculations have been 


DAMPING-OFF IN FOREST NURSERIES. FR 


made. The strain available is much less destructive to the pines 
than most of the P. debaryanum strains used, and as the fungus has 
never been isolated from coniferous seed beds it is not believed to 
be of any great importance in forest nurseries. 

(10) Phytophthora sp. from Pinus resinosa seedlings has been suc- 
cessfully used in inoculation on Pinus resinosa and in a preliminary 
test on P. ponderosa. The strains available have been less destruc- 
tive to the pines than Pythiuwm debaryanum and the stronger strains 
of Corticium vagum. It is not common. Its relation to Phytoph- 
thora fagi, the European damping-off parasite of both conifers and 
dicotyledons, which has not been reported in this country, is being 
investigated. j 

(11) A fungus referred to Pythium artotrogus, also obtained from 
damped-off Pinus resinosa, has indicated a very low degree of par- 
asitism on this host, even less than that shown by the Rheospor- 
angium and Phytophthora strains. An addition is made to the 
statements in a previous paper concerning the ability of Botrytis 
cinerea to cause damping-off in conifers. 

(12) The results of the cultural or direct examination of 742 dis- 
ease foci in seed beds of various conifers are reported. Pythium 
debaryanum in the plate-culture examination method, considered 
more reliable than direct examination, appeared in 51 per cent of 
the foci from untreated beds, while Corticitum vagum was found in 
19 per cent. In foci in beds treated with various disinfectants, P. 
debaryanum was identified in 38 per cent of the foci and C. vagum 
in only 4 per cent. When direct microscopic examination was sub- 
stituted for isolation, C. vagum was found on a larger proportion 
of the seedlings. It was not found at all in soil which had been 
heated. The relative ease with which it appears to be controlled by 
soil disinfectién is in agreement with its poor adaptation for aerial 
distribution. It was found more commonly in cases in which the 
seedlings were directly examined than when cultures were made. 
In view of the fact that at least some of the Corticium foci extend 
rapidly and include very large numbers of seedlings, it seems that 
the Corticium may be as important as P. debaryanum in causing the 
damping-off of pines. 

(13) Fusarium spp. have occurred more commonly in plate cul- 
tures than either of the above-mentioned fungi. Because little is 
known as to the parasitism of different species of this group on 
conifers, it is not possible to make any statement regarding the im- 
portance of the individual species. The evidence as a whole indi- 
cates so much importance for Pythium debaryanum, Corticium 
vagum, and for the /usarium spp. considered as a group that no one 
of the three can be safely said to be more important than the others. 
None of the other fungi considered appear to be of real economic 
rank in the United States. 


a 


90 BULLETIN 934, U. S. DEPARTMENT OF AGRICULTURE. 


(14) In an inoculation experiment on the roots of pines 14 months 
old, Cortictum vagum and Pythium debaryanum were found able- 
to cause the death of seedlings which had already developed rigid 
stems and to destroy the younger parts of the roots of seedlings which 
they were unable to kill. Indications were also obtained of similar 
but less vigorous action by Fusarium moniliforme and F. ven- 
tricosum. 

(15) Data are given confirming the general belief that thick sow- 
ing favors the disease and indicating that soil acidity is, in general, 
unfavorable. Preliminary data on the relation of temperature and 
moisture to the disease are also presented. The parasitic activity of 
Pythium debaryanum in steamed soil was in one extensive test con- 
siderably decreased, following the inoculation of the soil with various 
saprophytes; this indicates both that competition of different fungi 
is a factor to be considered and that the inoculation of treated soil 
with saprophytes may sometimes prove of value in increasing the 
efficiency of heat disinfection. It is pointed out that with such a com- 
plex of parasites capable of producing identical symptoms on a num- 
ber of different hosts, no relationship between environmental factors 
and the disease can be expected to hold in all cases. : 


LITERATURE CITED. 


ATKINSON, GEORGE F. 
(1) 1892. Some diseases of cotton. Ala. Agr. Exp. Sta. Bul. 41, 65 p., 


25 fig., 1 pl. 

(2) 1895. Damping-off. N. Y. (Cornell) Agr. Exp. Sta. Bul. 94, p. 
233-272, fig. 55, 6 pl. 

(3) 1902. Studies of some tree-destroying fungi. Jn Trans. Mass. Hort. 


Soc., 1901, pt. 1, p. 109-180. 
(4) Barre, H. W. 
1912. Cotton anthracnose. S. C. Agr. Exp. Sta. Bul. 164, 22 p., 7 pl. 
(5) Bary, A. DE. 
1881. Zur Kenntniss der Peronosporeen. Jn Bot. Ztg., Jahrg. 39, 
No. 38, p. 521-5380; No. 34, p. 5387-544; No. 35, p. 553-563; No. 36, 
p. 569-578 ; No. 37, p. 585-595 ; No. 38, p. 601-609; No. 39, p. 617-625, 
pl. 3. 
(6) BatEs, CARLOS G. 
1907. Timber fungi, with special reference to the pines. Jn 38th 
Ann. Rpt. Nebr. Hort. Soc., 1907, p. 201-208. 
and PIERCE, Roy G. 
1913. Forestation of the sand hills of Nebraska and Kansas. U. S. 
Dept. Agr., Forest Serv. Bul. 121, 49 p., 1 fig., 18 pl. 
BAUDISCH, FRIEDRICH. : 
(8) 1888. Ueber ‘ Phytophthora omnivora ” als Schidling des Buchenauf- 


(7) 


schlages. In Centbl. Gesam. Forstw., Jahrg. 14, Heft 8/9, p. 
382-385. | 
(9) 1903. Notizen tiber Septoria parasitica R. H., Fusoma Pini R. H. und 


Allescheria Laricis R. H. Jn Centbl. Gesam. Forstw., Jahrg. 29, 
Heft 11, p. 461-464. 
(10) BernHartTS EF. G. 
1918. Steam sterilization of seed beds for tobacco and other crops. 
U. S. Dept. Agr., Farmers’ Bul. 996, 15 p., 4 fig. 
(11) BEISSNER, LUDWIG. oi ba 
. 1909. Handbuch der Nadelholzkunde. Aufl. 2, xvi, 742 p., illus. 
Berlin. 
(12) BrackMAN, V. H., and WELSForD, E. J. 
1916. Studies in the physiology of parasitism. II. Infection by 
Botrytis cinerea. Jn Ann, Bot., v. 30, no. 119, p. 389-398, pl. 10. 
Literature cited, p. 397. 
(183) BorrKer, RIcHARD H. 
1916. Ecological investigations upon the germination and early 
growth of forest trees. In Nebr. Univ. Studies, v. 16, no. 1/2, p. 
1-90, illus., 5 pl. Bibliography, p. 88-89. 
(14) Bottey, H. L. 
1901. Flax wilt and flax sick soil. N. Dak. Agr. Exp. Sta. Bul. 50, 
p. 27-58, [17] fig. 
(15) Brown, JAMEs. 


1894. The Forester ... ed. 6 enl., ed. by John Nesbit. Vol. 2. Edin- 
burgh, London. 


v 


\ 


91 


92 BULLETIN 934, U. S. DEPARTMENT OF AGRICULTURE. 


(16) Brown, WILLIAM. ’ 
1916. Studies in the physiology of parasitism. III. On the relation 
between the “ infection drop” and the underlying host tissue, In 
Ann, Bot., v. 30, no. 119, p. 399-406. 

(17) BRUCHMANN, H. 

1885. Das Prothallium von Lycopodium. Jn Bot. Centbl., Bd. 21, 
No. 10, p. 809-318. 

(18) Bryant, ARTHUR. 

1871. Forest Trees for Shelter, Ornament, and Profit... 247 p., 
[12] pl. New York. 

(19) BucKINGHAM, EDGAR. 

1904. Contributions to our knowledge of the aeration of soils. U. 8. 
Dept. Agr., Bur. Soils Bul. 25, 52 p 

(20) Burcer, O. F. 

1918. Lettuce drop. Fla. Agr. Exp. Sta. Bul. 116, p. [25]-82, 3 fig. 

(21) BurcspoRF, FRIEDRICH AUGUST LUDWIG VON. . 

17838. Versuch einer vollstindigen Geschichte vorztiglicher Holzarten 
Bd. 1, Theil 1. Berlin. 

(22) Busse, W., PETERS, L., and ULRicH, P. 

1911. Ueber das Vorkommen von Wurzelbranderregern im Boden. In 
Arb. K. Biol. Anst. Land- u. Forstw., Bd. 8, Heft 2, p. 260-302. 
(Untersuchungen tiber die Krankheiten der Rtiben, von W. Busse.. 6.) 

Butter, E. J. 

(23) 1907. An account of the genus Pythium and some Chytridiacez. 
In Mem, Dept. Agr. India, Bot. Ser., v. 1, no. 5, 160°pa320een 
Literature, p. 142-147. : 

(24) 1918. Pythium bey dae Hesse. In Mem. Dept. Agr. India, Bot. 
Ser., v. 5, no. 5, p. 262-267, pl. 5. (Studies in Peronosporacex, by 
HK. J. Butler x G. S. Kulkarni.) 

BUTTNER, G. 


(25) 1908. Uber das Absterben junger Nadelholzpflanzen im Saatbeete. In 
Mitt. Deut. Dendrol. Gesell., No. 12, p. 81-82. 
(26) 1906. Etwas tiber den Keimlingspilz, Fusoma parasiticum yv. Tub. 


In Mitt. Deut. Dendrol. Gesell., No. 15, p. 282. ° 


(27) Byars, L. P., and GILBERT, W. W. 
1919. Soil disinfection by hot water to control the root-knot nema- 
tode and parasitic soil fungi. (Abstract.) In Phytopathology, v. 9, 
no. 1, p. 49. 


(28) CLiIntTon, G. P. 
1913. Report of the botanist, 1911 and 1912. In Conn. Agr. Exp. 
Sta., 36th Ann. Rpt. 1911-1912, pt. 5, p. [841]-453, pl. 17-28. 
(29) Cook, Met T., and Hetyar, J. P. 
1915. Diseases of grains and forage crops. N. J. Agr. Exp. Sta., 
Cire, 51, 8 p. ae 
(30) DAVENPORT, E. 
1907. Principles of Breeding ... xiii, 727 p., illus. Boston, New 
York. 
(31) DAwson, JACKSON. 
1885. The propagation of trees and shrubs from econ In Trans. 
Mass. Hort. Soc., 1885, pt. 1, p. 145-166. 


DAMPING-OFF IN FOREST NURSERIES. 93 


Duceear, B. M., and Stewart, F. C. 
(32) 1901. The sterile fungus Rhizoctonia as a cause of plant diseases 
in America. N. Y. (Cornell) Agr. Exp. Sta: Bul. 186, p. 51-76, 
[fig.] 15-28. ' 
(33) 1909. Fungous Diseases of Plants... xii, 508 p., illus., pl. Bos- 
ton, New York. a 
(34) 1916. Rhizoctonia solani in relation to the ‘“ Mopilz” and the ‘‘ Ver- 
mehrungspilz.” In Ann. Mo. Bot. Gard., v. 3, no. 1, p. 1-10. 
Literature cited, p. 9-10. 
EDGERTON, C. W. 


(385) 1915. Effect of temperature on Glomerella. Jn Phytopathology, v. 5, 
5, p. 247-259, 4 fig. 


(36) 1915. A new method of selecting tomatoes for resistance to the wilt 
disease. Jn Science, n. S., v. 42, no. 1095, p. 914-915. 
Epson, H. A. 
(37) 1915. Histological relations of sugar-beet seedlings and Phoma betae. 


Im Jour. Agr. Research, v. 5, no. 1, p. 55-58, pl. 1-2. 
(38) 1915. Seedling diseases of sugar beets and their relation to root-rot 
and crown-rot. Jn Jour. Agr. Research, v. 4, no. 2, p. 135-168, pl. 
16-26. Literature cited, p. 165-168. 
(39) 1915. Rheosporangium aphanidermatus, a new genus and species of 
fungus parasitic on sugar beets and radishes. Jn Jour. Agr. Re- 
Search, vy. 4, no. 4, p. 279-292, pl. 4448. 
and SHAPOVALOV, M. 
1918. Potato-stem lesions. Jn Jour. Agr. Research, v. 14, no. 5, p. 213- 
220, pl. 24-26. 
(41) Fawcett, H. S. 
1909. Report of plant pathologist. Jn Fla. Agr. Exp. Sta. Rpt. 
108/09, p. xlvi-lxii, fig. 7-12. 
(42) FiscHer, ALFRED, 
1892. Die Pilze Deutschlands, Oesterreichs und der Schweiz. IV. Ab- 
theilung: Phycomycetes. Jn Rabenhorst, L., Kryptogamen-Flora 
Aufl. 2, Bd. 1, Pilze. Leipzig. 
(43) Frep, E. B. 
' 1916. Relation of green manures to the failure of certain seedlings. 
In Jour. Agr. Research, v. 5, no..25, p. 1161-1176, pl. 88-84. Litera- 
ture cited, p. 1175-1176. 
(44) GaLtoway, B. T. 
1893. Report of the Chief of the Division of Vegetable Pathology. In 
U.S. Dept. Agr., 1892, p. 215-246, 1 fig., 4 pl. 
(45) GARDNER, JOHN. 
1890. [Damping-off.] Jn Amer. Gard., v. 11, no. 6, p. 347-348. 
(46) Grrrorp, C. M. 
1911. The damping-off of coniferous seedlings. Vt. Agr. Exp. Sta. Bul. 
157, p. 143-171, 10 fig., 4 pl. Bibliography, p. 171. 
(47) GILBERT, W. W. 
1909. The root-rot of tobacco caused by Thielavia basicola. U. S. 
Dept. Agr., Bur. Plant Indus. Bul. 158, 55 p., 5 pl. Bibliography, 
p. 4448. 


(40) 


94 BULLETIN 934, U. S. DEPARTMENT OF AGRICULTURE. 


(48) GLoyeEr, W. O. 
. 1913. The efficiency of formaldehyde in the treatment of seed pota- — 
toes for Rhizoctonia. N. Y¥: State Agr, Exp+ Sta. Bul) 370) 
417-481. 
(49) GoEBEL, K. 
1887. Ueber Prothallien und Keimpflanzen von Lycopodium inun-— 
datum. Jn Bot. Ztg., Jahrg. 45, No. 11, p. 161-168; No. 12, p. 177— 
190, ‘pl. 2. 
Gussow, H. T. . 
(50) 1912. Report of the Dominion botanist. In Canada Exp. Farms 
Rpts., 1911/12, p. 191-215, 4 fig., pl. 6-7.. : 
(51) 1917. The pathogenic action of Rhizoctonia on potato. In Phyto- 
pathology, v. 7, no. 3, p. 209-213, 1 fig. i 
HALstTEeD, Byron D. 


(52) 1892. Fungous troubles in the cutting beds. In Gard. and Forest, v. 5, 
no. 209, p. 91-92. 
@3) 1893. Fungi injurious to weed seedlings. In N. J. Agr. Exp. Sta. 


13th Ann. Rpt., 1891, p. 342-845. 

(54) Harris, J. ARTHUR. 

1915. The value of inter-annual correlations. In Amer. Nat., vy. 49, 
no. 587, p.. 707-712. cf 
Harrie, R. ve 

(55) 1876. Die Buchencotyledonen - Krankheit. Jn Ztschr. Forst- u. 
Jagdw., Bd. 8, p. 117-128. 

(56) 1879. Die Buchenkeimlingskrankheit erzeugt durch Phytophthora 
fagi'-M. In Forstw. Centbl., Jahrg. 23, Heft 3, p. 161-170. 

(57) 1880. Der Buchenkeimlingspilz, Phytophthora (Peronospora) fagi 
M. Jn Unters. Forstbot. Inst., Mtinchen, [Bd.] 1, p. 33-57, pl. 3. 

(58) 1880. Der Ahornkeimlingspilz, Cercospora acerina M. In Unters. 
Forstbot. Inst., Miinchen, [Bd.] 1, p. 58-62, pl. 4. : 

(59) 1883. Beschiidigung der Nadelholzsaatbeete durch Phytophthora 
omnivora (Fagi). Jn Forstw. Centbl., Jahrg. 27, Heft 12, p. 593— 
596. 

(60) 1892. Hin neuer Keimlingspilz. Jn Forstl. Naturw. Ztschr., Jahrg. 
1, Heft 11, p. 432-486, 4 fig. bas eae ! 

(61) 1894. Text-Book of the Diseases of Trees. Trans. by William 
Somerville... rey. and ed., by H. Marshall Ward. xvi, 331 p., 
illus. London. 

HARTLEY, CARL. 


(62) 1910. Notes on some diseases of coniferous nursery stock. (Ab- 
stract.) . Jn. Science; n. s., v. 31; no..799, p. Gao: 
(63) 1912. Use of soil fungicides to prevent damping-off of coniferous 


seedlings. Jn Proc. Soc. Amer. Foresters, v. 7, no. 1, p. 96-99. 
(64) 1913. The blights of coniferous nursery stock. U.S. Dept. Agr. Bul. 
44, 21 p. . - 
and MERRILL, THEODORE C. 
1914. Preliminary tests of disinfectants in controlling damping-off in 
various nursery soils. In Phytopathology, v. 4, no. 2, p. 89-92. 
(66) ——— and BRUNER, S. C. 
1915. Notes on Rhizoctonia. Jn Phytopathology, v. 5, no. 1, p. 73-74. 


(65) 


DAMPING-OFF IN FOREST NURSERIES. 95 


(67) Hartiey, Cart, and Pierce, Roy G. 5 
1917. The control of damping-off of coniferous seedlings. U.S. Dept. 
Agr. Bul. 453, 20 p., 2 pl. 


(68) MERRILL, T. C., and RHOADS, ARTHUR S. 
1918. Seedling diseases of conifers. Jn Jour. Agr. Research, v. 15, 
no. 10, p. 521-558, pl. B. Literature cited, p. 556-558. 
(69) and HAHN, GLENN G. 


1919. Oomycetes parasitic on pine seedlings. (Abstract.) In Phyto- 
pathology, v. 9, no. 1, p. 50. 


(70) HAwkins, Lon A. 
1916. The disease of potatoes known as “leak.” Jn Jour. Agr. Re- 
search, v. 6, no. 17, p. 627-640, 1 fig., pl. 90. Literature cited, p. 639. 
and Harvey, Ropnery B. 
1919. Physiological study of the parasitism of Pythium debaryanum 
Hesse on the potato tuber. Jn Jour. Agr. Research, v. 18, no. 5, 
p. 275-298, 2 fig., pl. 35-87. Literature cited, p. 295-297. 
(72) HeNnpDERSON, M. P. + 
1918. The black-leg disease of cabbage caused by Phoma lingam 
(Tode) Desmaz. In Phytopathology, v. 8, no. 8, p. 379-431, 10 fig. 
Literature cited, p. 481. 


(73) HEss, RICHARD. 
1900. Der Forstschutz. Aufl. 3, Bd. 2. Leipzig. 


(74) Hesse, RuDoLPH. 
1874. Pythium debaryanum, ein endophytischer Schmarotzer__ 76 
p. 2 pl. Halle. Inaug.-Dissert., G6ttingen. 


(75) HILTNER, L. 

1902. Die Keimungsv erhalgnicee der Leguminosensamen und ihre 
Beeinflussung durch Organismenwirkung. Jn Arb. K. Gsndhtsamt., 
Biol. Abt., Bd. 3, Heft 1, p. 1-102, 3 fig. 2 


and Prters, L. 
- 1904. Untersuchungen tiber die Keimlingskrankheiten der Zucker- 
und Runkelriiben. Jn Arb. K. Gsndhtsamt., Biol. Abt., Bd. 4, Heft 
3, p. 207-258. 
(77) HormMann, JULIUS V. 
1912. Aerial isolation and inoculation with Pythium debaryanum. 
In Phytopathology, v. 2, no. 6, p. 278. 


(78) Horne, WILLIAM T. 
1907. Algunos inconvenientes de los Semilleres de Tabaco. Cuba 
Estac. Cent. Agron. Circ. 28, 13 p. 


(79) JACZEWSKI, A. DE. 
1911. O gribnekh bolies makh figanexn porod i mierakh borbi s nimi. 
(Les maladies cryptogamiques des essences forestiéres, et la facon 
de les combattre.) [Russia.] Biuro po Mikologhii Etiopatologhii. 
(Bureau de Mycologie et de Phytopathologie.) St. Petersbourg. 
(Not seen. Title from Just’s Bot. Jahresber., Jahrg. 39 (1911), 
Abt. 1, Heft 3, p. 1249. 1913.) 
(80) JoHNsON, Epwarp C. 
1914. A study of some imperfect fungi isolated from wheat, oat, and 
barley plants. Jn Jour. Agr. Research, v. 1, no. 6, p. 475-490, 
pl. 62-63. Literature cited, p. 487-489. 


96 BULLETIN 934, U. S. DEPARTMENT OF AGRICULTURE, 


JOHNSON, JAMES. 


(81) 1914. The control of diseases and insects of tobacco. Wis. Agr. Exp. 
Sta. Bul. 237, 34 p., 9 fig. Literature cited, p. 60-61. 
(82) 1914. The control of damping-off disease in plant beds. Wis. Agr. 


Exp. Sta. Research Bul. 31, p. 29-61, 12 fig. 
(83) Jones, L. R. 


1908. The damping-off-of coniferous seedlings. Jn Vt. Agr. Exp. Sta. 
20th Ann. Rpt. 1906/07, p. 342-347. 


(S4) Kine, Wriirorp I. 
1912. The Elements of Statistical Method. xvi, 250 p., 26 fig. New 
York. 
(S85) KNECHTEL, WILHELM K, 
1914. Pythium de Baryanum Hesse ca provacator al unei boale de 
rasad de tutun. Supl. Bulet. Reg. Monop. Statul., Bucuresti, 48 p., 
pl. 5-7. (Abstract in Ztschr. Pflanzenkrank., Bd, 28, p. 61-62. 
1918. ) : 
(S86) Linpavu, G. 
1908. Die pflanzlichen Parasiten. In Sorauer, Paul, Handbuch der 
Pflanzenkrankheiten. Aufl. 8, Bd. 2. Berlin. . 


(87) LonpE, [G.] 
1874. Ueber einige neue parasitische Pilze. In Tagebl. 47, Versamml. 
Deut. Naturf. u. Arzte, Breslau, 1874, p. 203-206. 


(SS) McCLatcHir, ALFRED JAMES. 
1902. Eucalypts cultivated in the United States. U. S. Dept. Agr., 
Bur. Forestry Bul. 35, 106 p., 91 pl. Bibliography, p. 99-101. 


(S9) Mryakr, KIIcHt. 
1901. The fertilization of Pythinm debaryanum. Jn Ann, Bot., 
v. 15, no. 60, p. 663-667, pl. 386. List of papers cited, p. 665-666. 
MOLLER, F. 
1909. Kupfervitriol gegen die Vermehrungspilz. Jn Mdller’s Deut. 
Girt. Ztg., Jahrg. 24, No. 7, p. 77. 
(91) Mutu, FRANz. 
1908. Ueber die Infektion von Samereien im Keimbett. Jn Jahresber. 
Angew. Bot., Jahrg. 5 (1907), p. 49-82. 


NEGER, F. W. 


(90 


— 


(92) 1909. Beobachtungen und Erfahrungen tiber Krankheiten einiger 
Gehélzsamen. Jn Tharand. Forstl. Jahrb., Bd. 60, p. 222-252, 
4 fig. 

(93) 1910. Pathologische Mitteilungen aus dem Botanischen Institut der 


Kel. Forstakademie Tharandt. III. Ueber bemerkenswerte, in 
Siichsischen Forsten auftretende Baumkrankheiten. Jn Tharand. 
Forstl. Jahrb. Bd. 61, Heft 2, p. 141-167, 13 fig. 


and BUTTNER, G. 
1907. Ueber Erfahrungen mit der Kultur fremdliaindischer Koniferen 
im akademischen Forstgarten zu Tharandt. Jn Naturw. Ztschr. 
Land- u. Forstw., Jahrg. 5, Heft 4, p. 204-210. 
(95) NErsTLER, A. 
1899. Ueber das Vorkommen von Pilzen in Wachholderbeeren. Jn 
Ber, Deut. Bot. Gesell., Bd. 17, Heft 8, p. 320-825, pl. 25, 


(94) 


DAMPING-OFF IN FOREST NURSERIES. O7 
(96) Norton, J. B. 
1913. Methods used in breeding asparagus for rust resistance. U. S- 
Dept. Agr., Bur. Plant Indus. Bul. 263, 60 p., 4 fig., 18 pl. 
(97) PEARSON, G. W. 
1906. Two diseases of pines. Jn 37th Ann. Rpt. Nebr. Hort. Soe, 
1906, p. 280-232. 
(98) PELTIER, GEORGE L. 
° 1916. Parasitic Rhizoctonias in America. {ll. Agr. Exp. Sta. Bul. 
189, p. 283-390, 24 fig. Bibliography, p. 386-390. 


PETERS, L. 
(99) 1910. Eine hiufige Stecklingskrankheit der Pelargonien. Jn Garten- 
flora, Jahrg. 59, Heft 10, p. 209-2138, pl. 1582. ; 
(100) 1911. Ueber die Erreger des Wurzelbrandes. Jn Arb. K. Biol. Anst. 


Land-u. Forstw., Bd. 8, Heft 2, p. 211-259, 12 abb. (Unter- 
suchungen tiber die Krankheiten der Ritiben, von W. Busse. 5.) 
(101) PerTis, CLIFFORD ROBERT. 
1909. Problems in nursery practice. Jn Proc. Soc. Amer. Foresters, 
v. 4, no. 1, p. 42-49. 
(102) Prerce, Roy G., and HARTLEY, CARL. 
1919. Relative importance of Pythium and Rhizoctonia in coniferous 
seed beds. (Abstract.) In Phytopathology, v. 9, no. 1, p. 50. 
(1038) Pooreg, R. F. 
1918. Report of celery investigation. In N. J. Agr. Exp. Sta. 38th 
Ann. Rpt. 1916/17, p. 536-539. 
(104) PRILiievux, Ep. 
1895. Maladies des Plantes agricoles et des Arbres fruitiers et fores- 
tiers causées par des Parasites végétaux. T.1. Paris. 
(105) Rankin, W. Howarp. 
1918. Manual of Tree Diseases. xx, 398 p., 70 fig. New York. 
(106) RaTHBUN, ANNIE E. 
1918. The fungous flora of pine seed beds. Jn Phytopathology, v. 8, 
no. 9, p. 469-483. Literature cited, p. 483. 
REINKING, OTTo A. ° 
(107) 1918. Philippine economic-plant diseases. Jn Philippine Jour. Sci.,, 
v. 18, sect. A, no. 4-5, p. 165-274, 43 fig., 22 pl. 
(108) 1919. Philippine plant diseases. In Phytopathology, v. 9, no. 3, p. 
114-140. : 
RETAN, GEORGE A. 
(109) 1915. Charcoal as a means of solving some nursery problems. Iw. 
Forestry Quart., v. 13, no. 1, p. 25-30. 
(110) 1918. Nursery practice in Pennsylvania. Jn Jour. Forestry, v. 16,. 
no. 7, p. 761-769. 
(111) Rogers, STANLEY S. 
1913. The culture of tomatoes in California, with special reference 
to their diseases. Cal. Agr. Exp. Sta. Bul. 239, p. 591-617, 13 fig. 
(112) Rotrs, F. M. 
. 1915. Angular leaf-spot of cotton. S. C. Agr. Exp. Sta. Bul. 184, 
30 p., 9 pl. Literature cited, p. 30. 
(1135) Rots, P. H. f 
1913. Tomato diseases. Fla. Agr. Exp. Sta. Bul. 117, p. [83]-48, 
fig. 4-5. 
19651°—Bull. 934—21——_7 


98 BULLETIN 934, U. S. DEPARTMENT OF AGRICULTURE. 


(114) RosenBavuom, J. 
1917. Studies of the genus Phytophthora. Jn Jour. Agr. Research, — 
v. 8, No. 7, p. 283-276, 13 fig., pl. 71-77. -Literature citea 


p. 273-276. 
RUHLAND, W. 
(115) 1908. Beitrag zur Kenntniss des sog. “‘ Vermehrungspilzes.” In Arb. 
K. Biol. Anst. Land- u. Forstw., Bd. 6, Heft 1, p. 71-76, 3 abb. 
(116) 1908. Beitrag zur Kenntniss des sog. ‘‘ Vermeh: angspilzes.” In Mitt. 


K. Biol. Anst. Land- u. Forstw., Heft 6, p. 24-25. 
(117) SavDEBEcK, R. : 
1874. Ueber Pythium Equiseti. In Verhandl. Bot. Ver. Brandenb., 
Jahrg. 16, p. 116-124. 
(118) Saxton, W. T. 
1913. The classification of conifers. In New Phytol., v. 12, no. 7%, 
p. 242-262, 1 fig. List of references, p. 259-262, 
(119) ScHAAF, MARCUS. 
1915. Report of the State forester. In Rpt. Mich. Pub. Domain Com., 
1913/14, p. 60-106, [27] fig. 
(120) ScHELLE, E. 
1909. Die winterharten Nadelhélzer Mitteleuropas ... _ viii, 356 p., 
173 fig., map. Stuttgart. 
(121) ScHorz, EDUARD. 
1897. Rhizoctonia strobi, ein neuer Parasit der Weymouthskiefer. 
In Verhandl. K. K. Zool. Bot. Gesell. Wien, Bd. 47, Heft. 8, 
p. 541-557, 6 abb. 
(122) ScHrAamo, R. 
1904. Zum Absterben junger, unverholzter Nadelholzpflanzen im 
Saatbeet. Jn Mitt. Deut. Dendrol. Gesell.,; No. 13, p. 203. 
(123) Scott, CHARLES A. 
1917. A practical method of preventing the damping-off of coniferous 
seedlings. Jn Jour. Forestry, v. 15, no. 2, p. 192-196, 2 pl. 
(124) Srcrist, HORACE. 
1917. An Introduction to Statistical Methods... 482 p., 28 pl. 
New York. 
(125) Sexpy, A. D. 
1910. <A brief handbook of the diseases of cultivated plants in Ohio. 
Ohio Agr. Exp. Sta. Bul. 214, p. 307-456, i—vii, 105 fig. Literature 
of plant diseases, p. i—vii. 
and Manns, THOMAS F. 
1909. Studies in diseases of cereals and grasses. Ohio Agr. Exp. Sta. 
Bul. 203, p. 187-286, 7 fig., 14 pl. 
SHERBAKOFF, C. D. 
(127) ° 1916. Report of the assistant plant pathologist. In Fla. Agr. Exp 
Sta. Rpt. 1914/15, p. xciv—xceviii. 
(128) 1917. Report of the associate plant pathologist. In Fla. Agr. Exp. 
Sta. Rpt. 1915/16, p. SOR-98R, fig. 12-16. / 
(129) 1917. Some important diseases of truck crops in Florida. Fla. Agr. 
Exp. Sta. Bul. 139, p. [191]-277, fig. 75-112. 
(130) SmiTrH, RALPH E. ae 
1909. Report of the plant pathologist and superintendent of southern 
California stations, July 1, 1906, to June 30, 1909. Cal. Agr. 
Exp. Sta. Bul. 208, 68 p., 23 fig. Sone 


(126) 


(181) 


(182) 


(133) 


(134) 


(135) 


(136) 


(137) 


(138) 


(139) 


(140) 


(141) 


(142) 


(148) 


(144) 


(145) 


(146) 


(147) 


DAMPING-OFF IN FOREST NURSERIES. 99 


SmitH, RAutpH E., and SmiTH, ELizaseTu H. 
1911. California plant diseases. Cal. Agr. Exp. Sta. Bul. 218, 
p. [10389]-1198, 102 fig. 
SOMERVILLE, WILLIAM. 
1909. Rhizoctonia violacea, causing a new disease of trees. In 
Quart. Jour. Forestry, v. 3, no. 2, p. 184-135. 
SORAUER, P. 
1899. Der “ Vermehrungspilz.” In Ztschr. Pflanzenkrank., Bd. 9, 
Heft 6, p. 321-828, pl. 6. 
SPALDING, V. M. 
1899. The white pine (Pinus strobus Linnezus) rev. and enl. by B. E. 
Fernow. U.S. Dept. Agr., Div. Forestry Bul. 22, 185 p., 40 fig., 18 pl. 
SPAULDING, PERLEY. 
1907. A blight disease of young conifers. In Science, n. 8., v. 26, 
no. 659, p. 220-221. 
1908. The treatment of damping-off in coniferous seedlings. U. S. 
Dept. Agr., Bur. Plant Indus. Cire. 4, 8 p. 
1914. The damping-off of coniferous seedlings. Jn Phytopathology, 
v. 4, no. 2, p. 73-88, 2 fig., pl. 6. Bibliography, p. 85-87. 
TAYtor, MINNIE W. 
1917. Preliminary report on the vertical distribution of Fusarium in 
soil. In Phytopathology, v. 7, no. 5, p. 374-378. 


TILLOTSON, C. R. 
1917. Nursery practice on the National Forests. U. S. Dept. Agr. 
Bul. 479, 86 p., 6 fig., 22 pl. 
TUBEUF, C. VON. 
1888. Hine neue Krankheit der Douglastanne. Jn Bot. Centbl., Bd. 
33, No. 11, p. 347-348. 
1901. Fusoma-Infektionen. Jn Arb. K. Gsndhtsamt., Biol. Abt., 
Bd. 2, Heft 1, p. 167-168, 2 fig. 
1914. Hitzetot und Einschnitirungskrankheiten der Pflanzen, In 
Naturw. Ztschr. Forst- u. Landw., Jahrg. 12, Heft 1, p. 19-36, 
4 fig. 
VOGLINO, PIERO. 
1908. I funghi parassiti delle piante osservati nella Provincia di 
Torino e regione vicine nel 1907. Jn Ann. R. Accad. Agr. Torino, 
v. 50 (1907), p. 247-271. ; 
Warp, H. MARSHALL. 
1883. Observations on the genus Pythium (Pringsh.). Jn Quart. 
Jour. Micros. Sci., n. s., v. 283, no. 92, p. 487-515, pl. 34-36. 
Watson, B. M., Jr. 
1890. [Damping-off.] In Amer. Gard., v. 11, no. 6, p. 348. 
WESTON, WILLIAM H. 
1918. The development of Thraustotheca, a peculiar water-mould. 
Im Ann. Bot., v. 32, no. 125, p. 155-178, 2 fig., pl. 4-5. Literature 
cited, p. 171-172. 
WILSON, Guy WEST. 
1914. Studies in North American Peronosporales. V. A review of 
the genus Phytophthora. In Mycologia, v. 6, no. 2, p. 54-83, pl. 119. 
Bibliography, p. 80-82. 


ADDITIONAL COPIES 


OF THIS PUBLICATION MAY BE PROCURED FROM _ 


THE SUPERINTENDENT OF DOCUMENTS — 

GOVERNMENT PRINTING OFFICE 

e WASHINGTON, D.C, tis; 
AT 


10 CENTS PER COPY 
vO 


nT yh | 
: 


ee 


UNITED STATES DEPARTMENT OF AGRICULTURE 


BULLETIN No. 957 Wx 


"i 


Contribution from the Bureau of Plant Industry 
WM. A. TAYLOR, Chief 


Washington, D. C. PROFESSIONAL PAPER February 6, 1922 


INVESTIGATIONS OF THE WHITE-PINE BLISTER 
RUST. 


By Prruey Spaupine, Pathologist, Investigations in Forest Pathology. 


CONTENTS. 
Page. Page 
Scope of the investigations................--- 1 | Life history of Cronartium ribicola........... 24 
Origin and distribution of Cronartium ribi- The Peridermium stage on pines......... 24 
OG ae ee eee eee 3 The Cronartium stage on Ribes.......... 40 
Hosts of Cronartium ribicola................. 11 | Overwintering of Cronartium ribicola........ 68 
- Pines infected and likely to become Important dates in the life history of Cronar- 
PinteChediace f= se eke ues le wet. as of s 11 DUI TU DIC OURS eso se ws Lae es See a ae 72 
Inoculations of Cronartium ribicola on Control of the white-pine blister rust......... 73 
CIMT) 3 5 een RE GR ee eee sie 12 Significant factors which determine con- 
Species of Ribes that have been infected ee aS ee ge ee eee ieee 73 
HIPOMTNED Waste ciety mie cas nine sao Sie cok aie 14 Experiments in controlin Europe....... 76 
Inoculations of Cronartium ribicola on Experiments in controlin North America 80 
ieee. ged 2s Ses i ee ee ee 16 Status of the control of white-pine blister 
Susceptibility of Ribes species and varie- TUS btevse a cige en tes see messes vaccines ae 89 
ties to Cronartium ribicola............. 23'°|” Literature Cited’ 2. asso hawalad ea asckeb oes 90 


SCOPE OF THE INVESTIGATIONS. 


In a previous publication (131)! the writer collected data on the 
more practical aspects of the white-pine blister rust, as presented in 


European literature. 


Experience has shown that the white-pine blister rust has come to 


North America to stay and that most careful and searching investi- 


gations must be maintained to enable us to cope with it at all success- 
fully. Investigations in Europe have been carried on in a desultory 
way for 35 years. In North America they were begun less than 15 
years ago. Really intensive work has been in progress for only 
about 5 years. Considerable new experimental work has been done 
in Kurope since the appearance of this earlier publication. At various 
times since 1911 some of the more salient results of the investigation 
of Cronartium ribicola Fischer and the disease caused by it have been 
published (132 to 148, 180). During the years 1915 to 1919, inclu- 
clusive, publication has fallen far behind the investigations. 


1 The serial numbers in parentheses refer to ‘‘ Literature cited’’ at the end of this bulletin. 


46103— 21— Bull. 957—— 1 
\ 


4 BULLETIN 957, U. S. DEPARTMENT OF AGRICULTURE. 


No attempt has ever been made to collate and summarize the 
results of all the experimental work. The mass of information is so 
large and so scattered that it is nearly impossible for a single indi- 
vidual, even now, to learn what has been done. This condition is 
certain to become more and more acute as the extensive and intensive 
researches now under way progress. Various States are taking up 
work on this disease, and the multiplication of workers can only 
result in confusion and unnecessary duplication of work unless the 
ascertained data are arranged and made available for all. This 
bulletin aims to present the available information so that the gaps 
in our knowledge may be readily perceived and new investigations 
planned to the best advantage. 

The work of the Office of Investigations in Forest Pathology has 
been conducted under the direction and advice of the writer by the 
following persons: In 1915, G. F. Gravatt and Dr. G. R. Lyman; 
in 1916, Dr. R. H. Colley, G. F. Gravatt, and Miss M. W. Taylor; 
in 1917, Dr. R. H. Colley, G. B. Posey, G. F. Gravatt, Rush P. Mar- 
shall, and Miss M. W. Taylor; in 1918, Drs. R. H. Colley, H. H. York, 
L. H. Pennmgton, L. O. Overholts, A. S. Rhoads, T. C. Merrill, 
W. H. Snell, D. M. Benedict, and Miss M. W. Taylor; in 1919, Drs. 
R. H. Colley, H. H. York, and L. H. Pennington, D. M. Benedict, 
J. HK. Lodewick, W. H. Snell, P. R. Gast, Miss A. E. Rathbun, and 
Miss M. W. Taylor. Dr. G. G. Hedgcock made a comparative study 
of Cronartium occidentale and C. ribicola on Ribes on Block Island, 
R. I., in-1919. 

The work of Dr. L. H. Pennington, D. M. Benedict, and J. E. Lode- 
wick, in 1919, was maintained in formal cooperation with the New 
York State College of Forestry at Syracuse University. 

The endeavor has been to show plainly in this bulletin who did 
each piece of work without entering into details to an objectionable 
extent. 

The writer thanks the following people for unpublished data which ~ 
have been placed at his disposal: Mr. W. A. McCubbin, formerly of 
Canada; Dr. Ed. Fischer, of Switzerland; Dr. A. B. Borthwick, of 
Scotland; Mr.. A. D. Cotton, of Kew Gardens, England; Prof. L. 
Mangin, Museum of Natural History, Paris; Prof. EF. K¢glpin Ravn 
and Mr. J. Lind, of Denmark; Dr. L. O. Kunkel and Mr. W. Stuart 
Moir, of this country. 

The writer and his collaborators are indebted for material for 
experimental use to the Arnold Arboretum of Harvard University; 
the Dominion of Canada Central Experimental Farms; the Park 
Board of Rochester, N. Y.; the Conservation Commission of the 
State of New York; the Office of Horticultural and Pomological In- — 
vestigations and the Forest Service, of the United States Department 
of Agriculture. The Office of Blister-Rust Control has contributed 


WHITE-PINE BLISTER RUST. 3 


data, especially toward that appearing in the chapter on control, Table 
V, and the list of Ribes species infected in the different States. Much 
difficulty has been encountered in getting satisfactory translations 
of articles published in the Japanese, Russian, Dutch, Swedish, Nor- 
wegian, and Danish languages. Dr. EK. P. Meinecke has very kindly 
translated most of the Scandinavian and Danish articles. Mr. Rush 
P. Marshall and Miss M. W. Taylor, have aided in checking and col- 
lating the extensive data here presented. 

In this bulletin the behavior of Cronartiwm ribicola is given with 
considerable detail. So far as is now known, it agrees essentially 
with the Uredinales in general in its life history and physiology. 
This is the first species of Cronartium to be very intensively investi- 
gated, and as a representative of this important group of forest-tree 
fungi, a detailed knowledge of its life history must form the basis 
for the institution of new methods of management of white-pine 
forests. 


ORIGIN AND DISTRIBUTION OF CRONARTIUM RIBICOLA. 


Some writers (76, 90) have believed that Cronarteum ribicola went 
to Europe from America on Ribes aureum, that host being associated 
with it (but not exclusively) in the earlier discoveries of the disease 
in Kurope. Magnus, who was of this opinion at first (90), seems to 
have completely rejected this theory and now believes that the dis- 
ease came from western Siberia and the Swiss Alps, where it is sup- 
posed (26, 39, 40, 93, 130, 174) to have been endemic on Prunus cembra. 
In 1842 Klotsch issued in the exsiccate entitled “Herbarium vivum 
mycologicum, No. 490,’ a specimen labeled ‘‘Uredo ribicola”’ col- 
lected by Lasch at Driessen. Specimens have not been seen by the 
writer, and there is some uncertainty whether or not this is actually 
the uredinial stage of Cronartium ribicola. Sydow (155) gives it as 
a synonym of C. ribicola, but he is the only author known to the 
writer who does so. 

Cronartium ribicola was first certainly found by Dietrich (27) in 
the Baltic provinces of Russia in 1854. He found it upon Ribes 
mgrum, R. “rubrum,” and R. “palmatum,” and also upon Pinus 
strobus, although at that time it was not known that the two forms 
were stages of a single fungus. So far as can be determined from 
scientific literature, it was not again noted until 1861 in Finland (81), 
1865 in East Prussia (76), and 1869, when Eriksson (31) found it in 
Sweden on Aibes ngrum, and Hisinger (54) noted the first outbreak 


on pines in Finland. It had attacked Pinus strobus trees 30 years 


old and killed them. In 1883 Rostrup (115) reported an outbreak 
in Denmark on Pinus strobus trees 20 to 30 years old. It was evi- 
dently then generally spread over that country.  Stilllater, Klebahn 
(62, 63) and Tubeuf (169) record it as generally distributed over 


4 BULLETIN 957, U. S. DEPARTMENT OF AGRICULTURE. | 


Germany, and soon it had spread over the northern countries of 
Europe (91, 92, 93). It seems to the writer that this was an instance 
of the introduction of a foreign disease into Europe and its destruc- 
tive spread over most of that continent (39, 40). The fact that Pinus 
strobus had been grown extensively in Europe since its introduction 
there in 1705 (5), but was not known to have this disease until about 
1855, mn the light of our experience with this and other introduced 
plant diseases in North America, shows that this was a new disease 
which had reached Europe probably years before its discovery. 


y 


| Ue all 
\ f s : 
G 4 eS . 
her \hh 
ia 
} Res 
YR, . 
i ‘1G 
Bhp f i 
y i . 
N nee 
i nN 
1 2 JNIB IY” h 
r « 
‘: 
y ) 
§ 
N 


“\ 


Fic. 1.—Outline map of the Old World, showing the approximate distribution of Pinus cembra (oblique 
hatching) and ofits variety pumila (vertical hatching) together with the known distribution of Cronar- 
tium ribicola (black dots). Tree distribution furnished by the Forest Service, United States Departmen 
of Agriculture. | 


It is not certain that Cronartiwm ribicola is a native of the Swiss 
Alps (174). Schellenberg (123), in 1903, found Cronartiwm ribicola 
on a single 15-year branch of a tree of Pinus cembra about 200 years 
old in the Engadine Valley, Switzerland. He believed that the 
fungus was native there on this host. Yet this is the first known 
finding of the fungus on pine in that region. Ribes diseased with it 
were found there in 1895 (39, 123), showing it to be established in 
that locality then. It seems to the writer that the circumstances 
point plainly to the fungus having come into Switzerland some time 
previously, and that it is not endemic there; else it would have been 


WHITE-PINE BLISTER RUST. 5 


found much earlier, and more of it would have been found since 
then. Fischer (40) found the disease in 1915 spreading into western 
and northern Switzerland from without. 

It is generally supposed that Pinus cembra (26, 70, 93, 97, 98, 123) 
is the original pine host of this fungus. Figure 1 shows the distri- 
bution of P. cembra and its variety pumila in Europe and Asia. 
Cronartium ribicola is reported from Asia as follows: In 1879, from 


WS 


\ a 


Fic. 2.—Outline map of the United States, showing the known distribution of Cronartium ribicola and 
C. occidentale in North America to January 1, 1920. Localities for Cronartium occidentale are shown by 
black squares in’the Pacific coast and Rocky Mountian regions, the easternmost point being in western 
Kansas. Thisis whereit was found in 1892, but it hasnot been seen there since. Localities for C. ribicola 
are indicated by double cross hatching and black dots, nearly all being north of the Potomac and Ohio 
Rivers and east of the Mississippi River. Four pointsin southwestern Minnesota, eastern South Dakota, 
and northern Iowa were found to be due to diseased nursery stock which was shippedin. It is believed 
that the disease now has been eradicated in these outer western localities. The natural distribution of 
the eastern white pine is shownin the large cross-hatched area mostly east of the Mississippi River. The 
cross-hatched areas shown on the western half of the map indicate the known distribution of the western 
white pines. The pifion pines range as far north as southern Idaho but at altitudes different from those 
of the white pines. Cronartiwm ribicola is limited to the eastern white-pine area and was not known in 
North America until 1906. In most places where now found it has been traced to diseased imported 
white-pine stock. Cronartiwm occidentale is limited to that part of the western white-pine area in which 
pifion pines are native, where it appears also to be native. The two fungi are separated by a strip of 
prairie country about 500 miles wide. Distribution of the pines furnished by the Forest Service, United 
States Department of Agriculture. Distribution of Cronartium occidentale furnished by Messrs. Bethel 
and Posey, of the Offices of Investigations in Forest Pathology and of Blister-Rust Control, respectively. 


Bolschaja Inja River (131, 161); also from Tomsk and Minusinsk, 
Siberia (131). Quite recently it has been reported from Sakhalin 
Island and from Sapporo, Japan (156). Tulasne (175) in 1854 re- 
ported a Cronartium on Ribes, probably in India. Clinton has 
announced (13) the finding of Cronartium ribicola on dried herbarium 
specimens of Ribes collected by Wilson in the western part of the 
Province of Hupeh, China, in 1900. 


6 BULLETIN 957, U. S. DEPARTMENT OF AGRICULTURE. 


To. sum up briefly: Pinus cembra, the probable original pine host, 
ranges across northern Asia; and the fungus is reported from western, 
eastern, and central Asia, in some places where it may easily be 
endemic. | 

In North America, Cronartium ribicola was first found in 1906 at 
Geneva, N. Y. (3, 150). Later findings have indicated that it was 
here in the Northeastern States as early as 1898 (108, 136, p. 6). It 
might have been in North America a few years, but not many, before 
that date. This is supported by Clinton (13), who unsuccessfully ex- 
amined specimens of Ribes which are in some of the larger herbaria 
of the eastern part of this country. The writer has supplemented 


Fic. 3.—Outline map of the northeastern part of the United States, showing (by black dots) the known 
distribution of white-pine blister rust in North America to and including 1909. 


Clinton’s work by examining the Ribes specimens in several addi- 
tional herbaria. These include the Pringle herbarium at the Uni- 
versity of Vermont and the local collections of the University of 
Vermont; of Dartmouth College; of President Ezra Brainerd, of 
Middlebury College; of Mr. C. A. Weatherby, of East Hartford, 
Conn.; and of Mr. C. H. Bissell, of Southington, Conn. The most 
notable herbarium examined was that of the Boston Society of 
Natural History, which contains many New England collections 
made in the early years of the nineteenth century. Moreover, such 
keen fungus collectors as Farlow, Seymour, G. P. Clinton, Peck, 
Ellis, George Clinton, Stewart, and many others, never collected 
Cronartium ribicola until 1906, showing that it is a recent immi- 
grant. Since 1909, when it was first found in North America on 
white pines, Cronartium ribicola has spread until it is firmly estab- 


WHITE-PINE BLISTER RUST. 7 


lished in New England, New York, Wisconsin, Minnesota, and 
Canada. } 

It has been known since 1892 that there was a fungus on Ribes in 
the West much resembling Cronartvum ribicola, but until 1917 its 
alternate stage on pines was unknown. In that year the Office of 
Investigations in Forest Pathology began work upon this western 
fungus, which was soon found to have an alternate stage on Pinus 
edulis and P. monophylla in Colorado and Arizona (50, 114) and was 
named Oronartium occidentale. Its distribution and that of C. ribi- 
cola as known to January 1, 1920, is shown on the map (fig. 2). See 
figures 3 to 12 for the progress of C. ribicola by years from 1909 to 


Fic. 4.—Outline map of the northeastern part of the United States, showing (by black dots) the known 
(cumulative) distribution of white-pine blister rust in North America to and including 1910. 


1918, inclusive. Cronartium occidentale is found in localities where 
it could hardly be an introduction, as the Ute Indian Reservation in 
southwestern Colorado, where it was found by Bethel in 1897; also 
- In the Mesa Verde region, where no cultivated Ribes or pines have 
ever been introduced. fibes aureum is native in the Rocky Mountain 
region and is a favorite host for Cronartium occidentale as well as 
C. rebicola. 

Since Ribes aureum was intimately associated with Cronartium 
ribicola in its earlier known occurrences in Europe, an inquiry has 
been made into the possibility of the fungus being American in origin 
and its being introduced into Kurope on &. aureum when that plant was 
first sent there. The facts thus far determined are? that R. aurewm 


2 Spaulding, Perley. Ribes aureum not an original host of Cronartium ribicola. In manuscript. To 
be published in Phytopathology. 


8 BULLETIN 957, U. S. DEPARTMENT OF AGRICULTURE. 


is definitely stated to have been introduced into England (the proba- 
ble first point of introduction in Europe) in 1812 by Thomas Nuttall. gs 
Evidently Nuttall collected the seeds of this plant while on a botanical 4 


Fig. 5.—Outline map of the northeastern part of the United States, showing the known distribution of 
white-pine blister rust in North America to and including 1911. 


Fic. 6.—Outline map of the northeastern part of the United States, showing (by black dots) the known 
distribfition of white-pine blister rust in North America to and including 1912. 


trip in 1811 with John Bradbury up the Missouri River to a point 1 
the eastern part of Mercer County, N. Dak. His material must have 
been shipped quite promptly to England, as Fraser’s nursery at 


‘ 


WHITE-PINE BLISTER RUST. 9 


Chelsea, London, in 1813, offered for sale plants “‘collected in Upper 
Louisiana and principally on the River Missourie, North America.’ 
There is reason to believe that these were Nuttall’s plants. The 


Fic. 7.—Outline map of the northeastern part of the United States, showing (by black dots) the known 
distribution of white-pine blister rust in North America to and including 1913. 


Fic. 8.—Outline map of the northeastern part of the United States, showing (by black dots and cross 
hatching) the known distribution of white-pine blister rust in North America to and including 1914. 
The cross hatching in this and the following maps indicates areas which are generally infected. 


plant of interest to us is listed as Ribes longvflorum, a new species 
from the Missouri. This is now known as R. odoratum Wendland, 
which is the common form generally cultivated in the eastern United 


10 BULLETIN 957, U. S. DEPARTMENT OF AGRICULTURE. 


States under the name R. aureum. This appears to be the form most 
common in cultivation in Europe, but the true R. aurewm of the 
Rocky Mountain region and the plains of the Columbia was evi- 
dently introduced there soon after R. odoratum, if not at about the 
same time. Pursh may have referred to living plants of true R. 
aureum but we have no means of determining this. Lindley in 1828 
made the new species FR. tenuiflorum (now R. aureum) and says 
“Clit. 1812,” evidently meaning “cultivated in 1812.’’ He had this 
so definitely distinguished from our #. odoratum that his statement 
is fairly conclusive that R. aureum actually was introduced into 
England the same year as was Rf. odoratum. The agent introducing — 


Fic. 9.—Outline map of the northeastern part of the United States, showing (by black dots and cross 
hatching) the known distribution of white-pine blister rust in North America to and including 1915. 


Rf. aureum can not be determined beyond question. There appears 
to be little doubt, because of the difficulty of communication at that 
time, that both plants were carried from their native regions to the 
eastern part of this country in the form of seeds. Cuttings may have 
been sent to Europe but it is more likely that seeds were sent. Seeds 
would not be likely to transmit a rust which does not attack the 
fruit. It does not seem possible that a fungus like Cronartwum 
ribicola could be carried to Europe on these plants without becoming 
established in the Eastern States. Moreover, these species of Ribes 
apparently were introduced into Great Britain first. The fungus 
was not known in Great Britain until 1892, long after it was prevalent 
in other northern European countries. It appears that Cronartium 
ribicola was carried to Great Britain on infected white pines from 
northwestern Germany. The evidence appears to show that Cro- 


tal WHITE-PINE BLISTER RUST. +1 


nartium ribicola attacked Ribes aurewm and R. odoratum after they 
reached Europe. Their susceptibility also indicates that they are 
not original hosts of the fungus. | 

Summing up the evidence available, it appears (1) that Cronartiwm 
ribicola is Asiatic in origin; (2) that it spread in the early 1800’s 
into western Russia, whence it eventually spread well over Europe 
(41); (3) that it was brought to North America in young trees of 
Pinus strobus; and (4) that comparative studies (50) show that 
Cronartium occidentale is distinct. 


HOSTS OF CRONARTIUM RIBICOLA. 
Pines Infected and Likely to Become Infected. 


Cronartium ribicola has attacked 11 of the white pines in the 
countries, Provinces, and States indicated in the following list: 


Pinus aristata Engelmann in England (20a). 

ayacahuite Ehrenb. in Scotland and England.* 

cembra L. in Russia (58, 93), Switzerland (39, 40, 123, Germany (72, 77, 174, 177), 
U.S. A. (Mass., Minn.).* 

excelsa Wall. in Denmark (120), Germany (99), U. S. A. (Mass.). 

flexilis James in Germany (173), Sweden,® U. 8. A. (Mass., Minn., Iowa). 

koraiensis Sieb. and Zucc. in Sweden.® 

lambertiana Douglas in Belgium (101), Germany (62, 173). 

monticola Douglas in Belgium (101), England (79), Germany (70). 

parviflora Sieb. and Zuce. in U.S. A. (Mass.). 

peuce Gris. in Germany (173). 

strobus L. in Austria-Hungary (178), Belgium (70), Denmark (81, 115, 117, 119, 
120), Finland (54, 83), Switzerland (40), France (70), Germany (70), Great 
Britain (111), Holland (70), Ireland (42), Norway (70), Russia (27, 58, 120), 
Siberia (161), Sweden (131°), Canada—Ontario (23, 56) and Quebec (107, 
121), U. S. A. (Conn., Ind., Iowa, Maine, Mass., Mich., Minn., N. H., N. J., 
N. Y., Ohio, Penn., R. I., S. Dak., Vt., Va., Wis.). The fungus has occur- 
red in a number of these States only on diseased pines shipped from outside 
points. 


In every case the disease attacked these pines naturally in out- 
break areas of Europe and North America and is not known to attack 
any of the pitch pines, although some of them have been present in 
infected areas. Whenever the other white pines are continuously 
exposed to the fungus they will be likely to develop the disease. The 
blister rust was first found on the different species of pines as follows: 


Pinus strobus. Russia in 1854. Pinus ayacahuite. Great Britain in 1908. 
lambertiana. Germany in 1887. . flexilis. Germany in 1914. 
cembra. Russia in 1890. peuce. Germany in 1914. 
monticola. England in 1898. parviflora. United States in 1916. 
excelsa. Denmark in 1902. koraiensis. Sweden in 1920. 


aristata. England in 1907. 


3 Communicated in a private letter from Dr. A. B. Borthwick, of Scotland. 

4 The statements concerning occurrences in North America are based on records and specimens in the 
Office of Investigations in Forest Pathology. 

5 Trivate letter from W. Stuart Moir, Office of Blister-Rust Control. 


12 BULLETIN 957, U. 8S. DEPARTMENT OF AGRICULTURE. 


Sudworth (154) recognizes eight species of the white pines (exclu- 
sive of the pifion pines) for North America (fig. 2) but does not treat 
those of the Old World. Shaw (126), who treats the pines of the 
world, also recognizes eight North American species of white pines. 
He is, therefore, taken as the authority for the pines in this bulletin. 

The white pines of the world are grouped by Shaw as follows: 
Genus Pinus. 
Section Haploxylon. 
Subsection Cembra. 

Group I. Cembre. 
koratensis +-. 
cembra +. 
albicaulis. 

Group II. Flexiles. 
flexilis +. 
armandi. 

Group III. Strobi. 
ayacahuite (or strobiformis) +. 
lambertiana +. 
parviflora +. 
peuce +. 
excelsa +. 
monticola +. 
strobus +. 

Subsection Paracembra. 

Group IV. Cembroides—pifion pines. 

Group V. Gerardianze—pifion pines. 

Group VI. Balfourianz. 
balfouriana. 
aristata+. 


In examining the above synopsis, note the grouping of the known 
susceptible species (which are indicated by +) especially in the first 
three groups which make up the subsection Cembra. Investigations 
of outbreak areas in Europe where the various species of pine have 
been present might yield on this point most interesting and valuable 
information which can be obtained in no other way. 


Inoculations of Cronartium Ribicola on Pines. 


Klebahn (68, 71) appears to be the first Kuropean investigator 
who has inoculated pines with Cronartium ribicola and who has pub- 
lished his results. He inoculated young Pinus strobus trees with 
pycnospores, but with no success (70, p. 387). Inoculations made by 
him with sporidia in 1888 were rendered worthless because the pines 
were probably infected naturally before the test was made (71). On . 
August 27, 1903, Klebahn (71) made inoculations on two young 
Pinus strobus trees by suspending telia-bearing leaves of Ribes mgrum 
above the trees and covering them with a large bell jar. On June 19, 


WHITE-PINE BLISTER RUST. 138 


_ 1904, the pines were examined. At that time some of the new shoots 
bore abnormal leaves of a juvenile type singly, instead of in fives. 
The new twigs were abnormally pale in color.- Many of the leaves 
of the growth of the previous year were spotted with yellow through 
their entire thickness. These yellow spots were especially plentiful 
near the base of the leaves. Microscopic examination showed abun- 
dant mycelium to be present in the yellow areas. Later pycnia devel- 
oped on the twigs near the bases of the spotted leaves. 


Fic. 10.—Outline map of the northeastern part of the United States, showing (by black dots and cross 
hatching) the known distribution of white-pine blister rust in North America to and including 1916. 


In 1914, Tubeuf (174) inoculated trees of Pinus strobus, P. lam- 
bertana, P. cembra, P. cembroides, P. excelsa, P. peuce, P. parviflora, 
P. flerilis, and P. montezumae with sporidia of Cronartium ribicola 
under controlled conditions. In 1917, ecia were produced on some 
of the P. strobus. Yellow spots were produced on the leaves of P. 
lambertiana, but no further development of. the fungus occurred. 
Spots which were doubtfully caused by the fungus were noted on P. 
cembroides. No other species became infected. Infections were 
produced directly on the juvenile leaves, on mature leaves, and 
through the epidermis of the lengthening buds of the young shoots. 

In North America, the writer seems to have been the first to 
moculate successfully young Pinus strobus trees with sporidia (133, 
134). The inoculations were made both with and without wounds 
in the young bark, telial columns being used for inoculum. Pycnial 
drops were produced by one tree unwounded and by one which was 


U 
: \ 
14 BULLETIN 957, U. S. DEPARTMENT OF AGRICULTURE. | 


wounded. At this stage slugs ate the infected bark and prevented 
further development of the fungus. In 1916 and in 1917, 150 
zeclospore inoculations were made on leaves, on twigs of various ages, 
and on branches of P. strobus trees up to six years. No infections 
have resulted. | 

Clinton and Miss McCormick (14, 15), have published details of 
successful inoculations, through the leaves, with sporidia on P. 
strobus. Inoculations were unsuccessful upon leaves of P. excelsa, 
P. flexilis, P. koraiensis, and P. cembra; also on the pitch pines P. 
resinosa, P. sylvestris, P. densiflora, and P. austriaca. Yellow spots 


Fic. 11.—Outline map of the northeastern part of the United States, showing (by black dots and eross 
hatching) the known distribution of white-pine blister rust in North America to and including 1917. 


have been secured on leaves of P. lambertiana, P. pinea, and P. 
sabimiana. 

Cross-inoculations that are known to have been successful up to 
July 1, 1920, are shown in Plate I. 


Species of Ribes That Have Been Infected Naturally. 


In Europe and North America, where extensive outbreaks of 
Cronartium ribicola have occurred, a considerable number of species 
of Ribes have been found naturally infected by the fungus. Prac- 
tically all of the cultivated species and most of the wild ones take the 
disease in every extensive outbreak area. More species have been 
found infected in Europe than in North America, because outbreaks 
have been discovered there in botanical gardens, parks, and nurseries 


a) a al 


WHITE-PINE BLISTER RUST. 15 


where extensive collections of the different species of Ribes were 
located, and hence more species have been subjected to attack. 

In Europe the following species have become infected naturally: 
Ribes aciculare Smith, R. affine H. B. K., R. alpinum L., RB. ameri- 
canum Mill., R. aureum Pursh, R. biebersternia ine R. bracteosum 
Douglas, R. cynosbati L., R. divaricatum Douglas, & t. glandulosum 
Grauer, R. gordonianum hybrid, R. hartellum Michx., R. wriguum 
Douglas, R. menziesii Pursh, R. missouriense Nuttall, R. multiflorum 
Kit., R. nigrum L:, R. niveum Lindl., R. odoratum Wendl., BR. oxya- 
canthoides L., R. petraeum Wulf., R. reclinatum L., R. rohutuaatatnuns 
Michx., R. rubrum L., R. sanguineum Pursh, R. setosum Lindl., R. 
triste Pallas, R. vulgare Lam. 

The names of species of Ribes of North America are based on the 
treatment of the North American species by Coville and Britton in 
“North American Flora” (22) and of species of the other continents 
on that of Janczewski in “Monographie des Groseilliers, Ribes L.’’ 
(60). For the sake of convenience the currants and gooseberries are 
kept in the single genus Ribes. 

As recently as 1914 (136) the fungus had not been found in North 


_ America attacking any wild species of Ribes. Since then it has 


been found attacking an increasing number of wild Ribes, as addi- 
tional species are subjected to infection by the spreading and multi- 
plication of the known outbreak areas and as new ones are dis- 
covered. To date it is known to have been found attacking naturally 
the following species of Ribes in the States and Provinces named: 


Ribes americanum (floridum).—Maine, New Hampshire, Vermont, Massachusetts, 

Rhode Island, New York, Wisconsin, Minnesota, and Ontario. 

cynosbatt.—Maine, New Hampshire, Vermont, Massachusetts, Rhode Island, 
Connecticut, New York, New Jersey, Wisconsin, Minnesota, and Ontario. 

glandulosum (prostratum).—Maine, New Hampshire, Vermont, Massachusetts, 
Connecticut, New York, Wisconsin, Minnesota, and Ontario. 

lurtellum.—Maine, New Hampshire, Massachusetts, New York, Wisconsin, and 

* Minnesota. 
irriguum.—New York. 
 lacustre-—Maine, New Hampshire, New York, and Wisconsin. 

missourtense.—New York, Minnesota, and Wisconsin. 

mgrum.—Maine, New Hampshire, Vermont, Massachusetts, Rhode Island, 
Connecticut, New York, New Jersey, Wisconsin, Minnesota, Ontario, ane 
Quebec. 

odoratum.—Maine, New Hampshire, Vermont, Massachusetts, Rhode Island, 

Connecticut, New York, Minnesota, and Ontario. 

reclinatum (grossularia).—Maine, Vermont, Massachusetts, New York, Wiscon- 
sin, Minnesota, and Ontario. 

rotundifolium.—New York. 

triste—Maine, New Hampshire, Massachusetts, Wisconsin, Minnesota, and 
Ontario. 

vulgare (rubrum).—Maine, New Hampshire, Vermont, Massachusetts, Rhode 
Island, Connecticut, New York, Wisconsin, Minnesota, and Ontario. 


16 BULLETIN 957, U. S. DEPARTMENT oF AGRICULTURE. 


Inoculations of Cronartium ribicola on Ribes. 


In 1888, Klebahn (63, 64) made the first known successful inocu-} 
lations of this fungus on Ribes. Since that time a number of inocu-} 
lations have been made in Europe by Klebahn (65, 66, 67, 68, 69, 
70), Wettstein (70), Rostrup (118, 119, 120), Sch¢yen (124) , Eriksson | 
(31, 33), Tubeuf (167), Hennings (53), Sorauer (129), Tranzschel 
(92), Neger (100), Ewert (36, 37), Naumann (36), and Jaczewski 
(58, 59). The published accounts of most of these experiments are 
very fragmentary and lack many essential details. In fact the 
attitude of the European investigators seems to have been that of | 
mild interest in a new fungus rather than that of intensive study of 
a new parasite and of the destructive disease caused by it. 


377 Vy 
J “i 7 
° % ey Up, L 
4 thoes o Y 7p, 


Fig. 12.—Outline map of the northeastern part of the United States, showing (by black dots and cross 
hatching) the known distribution of white-pine blister rust in North America to and including 1918. For 
distribution to the end of 1919, see figure 2. 


Since the summer of 1909 the writer and his collaborators have 
made repeated tests under controlled and natural conditions of all 
species and of all varieties of the cultivated species of Ribes that 
could be obtained. In the earlier work complete records were not 
kept, but in the last few years the records were made to cover all points 
likely to be of value. Hundreds of inoculations have been made on 
the more susceptible species to keep the fungus growing in vigorous 
condition, without records being made. It was felt that green- 
house tests alone were not dependable for susceptibility data. 
Therefore, in 1916, a test plat was located upon Block Island, R. I. 
This island lies 12 miles from the hearest projecting point of the 
mainland and 15 miles or more from the main shore line. No white 
pines are on the island and but few cultivated Ribes. It was chosen 


\ nevadense 


parishil 


nigrum 


WA 


nigrum aconitifolium 


befraeum 


Bul. 957, U. S. Dept. of Agriculture. 
Pinus i= Ribes:- 
hhibes— 
cembra albinum 
albinum Macrophyllum nae 
americanum —~—-— . al pes re 
aureum albinum macrophyllum 
avreum palmalum foeminive “i : americanum 
avreum X reclinalum aureum 
bethmontfi ae g bracteosum 
bracteo sum --=-=- -=----< - fj emia 
carrie€ret Sy YS 7eerenm 
G10 Y coloradense 
coloradense , Uf _-crventum 
cruentum ve, es _culverwellii 
lexilis culver wellii Vee curvatum 
f curvalum et 
cynosbali’ —— y iacantha 
diacantha LV, divaricafum 
divaricalum eryth rocarpum 
erythrocarpum -Fasciculalum 
/ aseiculaton: ° ° fasciculalum chinense 
YU hy (fasciculalum chinense fasciculatum japonicum 
Y; Y/ Uy / YW Wy fasciculalum japonicum ae paawr 
yyy vy, ey. fontanum jes enayense 
y LA ff, fontenayense fu ae 
hy hy, fulurum le ‘ 
Yyy Ys H ji Sy glandulosum 
lamberfiana YU Yo J sirasi Ap Mice 
Y Yio glandulosum Se Yi, alin 
4 Le luTinosum ‘ Z gordonianum 
aya pies rdoni : wa \ hesberium 
gordonianum < SS< Ve SSS eee 
gracillimum BSE SDS CX bee um 
hesperium Pe . ZZ Za S peti 
hirtellum --— ---- - -— -@——-—=pRF- << ) 
* TSS Ze . <-> Irriguum 
holosericeun QE yee Ss 
Inebrians Le yo lett ie 
i ——e eplanthum 
inerme— . — —- : zt 
i maton SS: S< - lobbii 
me. Ne *<S malyaceum 
orice ean — re a BX “S : malvaceum viridifolium 
lentum SS aa ox : menziessi 
— < x Z i i 
lebanthum IN WY, Ze ge EL SESS missouriense 
fobbii : DPS ss SBOE <ASSSSS nevadense 
malyaceum ¥ SS SSS SR egy = 
j Pee rt SEX nigrum aconififolivm 
malvaceum viridifolium xs : lat 
os EOS es. 
missouriense ~ & 3 marae 
: ; R nigrum lacinialum . 
trob missourienseX reclinatum EN oeere 
SirobusS Iti | » == oralu: 
=i mull oro — XA SE = - =P onsacantheides 
Ss 
SN 


nigrum. crispum 
nigrum fFasciculatum 
nigrum folic argentea—« Za 
nigrum raicin Ep 
odoralum --— -----— 
oxyacanthoides—-—. 
peTraeum 

betraeum alroburbureum 
reclinalum 


ae 


reclinalum x missouriense 
reclinalumX rotundifolium 
robuslum. 


rotundi folium 
rubrum 
rubrum petrowalskyanum 


rubrum hubscens 
\ \ rubrum scandicum 
\\ rubrum siberica 


sanguineum 


TrisTe—— ———— 
Villosum 

ViscosjSsimum 

vulgare 

vulgare macrocarbum 
wolfii 


SS z 


pbefracum alroburbureum 
reclinalum 
reclinatum X missouriense 


SS 


robuslum 

rubrum 

rubrum schleclendali 
rubrum petrowalskyanum 
rubrum scandicum 
sanguineum 

sanguineum albidum 
sanguineum floro pleno 
sefosum 

sbeciosum 

» succirubrum 


Tenve 
-—triste 
viburnifolium 
ilosum 
vulgare 
wulgare ™acrocarf. 


DIAGRAM SHOWING CROSS-INOCULATIONS MADE WITH CRONARTIUM RIBICOLA TO JANUARY, 1921, INCLUDING THOSE MADE BY EUROPEAN INVESTIGATORS. 


Drawn by Rush P. Marshall. 


46103°—21. 


PLATE |. 


Pinus:— 


slrobus 


(To face page 16.) 


. 4 teh 


tt: aauiliotg ats jqatd 2 : 


u 


oe Nh ; 


nt ao 
tit hsars mA 
Levon — 
yids hs a 
reer et 
Wey 


Vigil 


WHITE-PINE BLISTER RUST. 17 


as the safest place for such work at that time. In midsummer, 1916, 
before the disease was fairly started on the bushes on the island, it 
was found to be pretty generally distributed over New England. on 
Ribes, having plainly been widely disseminated there before the 
Block Island experiment was started. Conditions on the island are 
not very favorable for Ribes and are decidedly unfavorable for white 
pines. Pinus nigra var. austriaca-is the only pine seen on the island, 
and it occurs only in protected hollows. 

Table I presents the general results of tests made in the green- 
house where inoculations were made with both eciospores and 
urediniospores. A preliminary statement has been published, giv- 
ing the earlier results of this work (147). This table is to be inter- 
preted as follows: 

In the columns headed ‘‘Susceptibility,’’ a single cross (<) means shght infection, 
two crosses ( X) mean a medium degree of infection, and three crosses (X X X) Mean 
heavy infection. 

There are no means of knowing what degree of susceptibility was indicated by 
the experiments of European and Canadian investigators, whose results are included 
in section 1 of Table I. The foreign experimenters are first listed alphabetically 
under each species of Ribes, then the work done in this country is given in a similar 
manner. The varietal tests (sections 2 to 4 of Table I) are wholly the work of the 
Office of Investigations in Forest Pathology, there being practically no data in 
foreign literature on inoculations of horticultural varieties. 


In numerous cases but a single test has been made as yet; but the 
general behavior of the tested plants in the spread of the fungus, 
the type of its fruiting, etc., during the rest of the season are con- 
sidered in the final estimate of susceptibility. When a single test 
has been made under favorable conditions,-it is believed that the 
results are fairly indicative of the susceptibility of.the species or 
variety tested. Many tests were made under conditions known to 
be adverse, and the negative results are largely due to this cause alone. 
But these tests are given with the others to give some idea of what 
has been done. Scanty numbers of tests are often due to the Ribes 
stock dying before a second test could be made. This is true of 
many cuttings which made a weak start and did not survive potting. 

In sections 2 to 4 of Table I, relating to the varieties of Ribes, an 
attempt has been made to use varietal names that are intelligible to 
horticulturists as accepted by the American Pomological Society. 
Acknowledgment is made to the Office of Horticultural and Pomo- 
logical Investigations of the United States Department of Agriculture 
for help in this matter. In some cases varietal names are given 
which are considered to be synonyms of others in the list; but in such 
cases the stocks used under the two names were evidently different. 
Varieties and even species of Ribes supplied by nurserymen are often 
other than what they purport to be, and in some cases they are 
mixtures of two or more distinct things; hence, the varietal names can 
not be taken as being absolutely reliable. 

46103°—21—Bull. 957-2 


‘ 


18 


BULLETIN 957, 


U. S. DEPARTMENT OF AGRICULTURE. 


TABLE I.—Results of inoculations made on various species and horticultural varieties of 
Ribes, showing data on susceptibility + im the greenhouse and out of doors on Block Island, R.I. 


Species or variety 
and investigators. 


Inocula- 
tions. 


Infec-/ Num- 
tion. | ber. 


Susceptibility. 


Src. 1.—Species of 
Ribes.a 


R. alpestre: 
Gravatt. 


Wepera:: .¢33.af 


Gravatizicc...-- 
Marshall......... 
TRY IOs s aep = = 
R.alpinum macro- 
se ihe 


R. americanum: 


Sorauer-s232 2 6S. - 


Gravatt.” -.2.5-< 
Spaulding....... 
Tavior.. 2 = cee. > 
MONG oh nee 


ee 


Hedgcock Baas 
Marshall......... 


R. aureum ‘‘palma- 
tum foeminum?’’; 
Spaulding....... 
R. aurem xX recli- 
natum: 
Gravatt. S224: 
. bethmontii: 
Spaulding.-...... 
. bracteosum: 
Gravatt......... 


Gravatt. 


row BB 


Gravatt 2+...204. 
Marshall Pe ae 
Spaulding.-...... 
Wawlorve ese 2 
. coloradense: 
Spaulding....... 
PA VION ot et ocnts ns 
. cruentum: 
Gravatt..-.....-. 


Bb 


GPOWAULS -bnice au 


. curvatum: 
Gravatti «222.4 
Marshall......... 
Spaulding....... 
TAVlON: ae gate 

. cynosbati: 

wbeutiuc oes 


coo FOr 


- OO 


— 
to 


— tt et et ww an Nore i Noord we we] 
Ke Or WE SN NK WNW 


—_ 


NNR w 
Nowe > 


eee eeee 


xX 


bs 


ee 


eee eee ee 


xX 


Species or variety 
and investigators. 


Src. 1—Species of 
Ribes—Contd. 


diacantha: 
Gravatt aoe ee 


R. 


ire 
Rostiap .i2..i- 


Spaulding. ...... 
ee eee iy ene 


R. 


R. fontenayense: 
Gravett.-.sec> 


Gravatt. 


Spaulding....... 
Taylor. 22002 te 
. glutinosum: 
Gravatt: = J.34s-5 
Spaulding......- 
. gordonianum: 
Gravatt. {02 -5:< 
Spaulding......- 
. hesperium: 
Gravatt. .......- 


R. hirtellum X re- 
celinatum: 
Hedgcock. ...... 
R. holosericeum: 
Gravatt: 2c).22e6 
R. inebrians: 
Hedgcock.....-- 
R. inerme: 


aSummary of tests made in foreign countries and in America. 


TInocula- 


tions. 


Susceptibility. 


Infec-|Num- In the | Out of 


tion. 


ber. 


green- 


doors. 


_ 
Pe SO NWE He OF 


iw) 
oe eke 


One 


— 
Noe NW NWwWO 


— Nob 


i] 
ow 


— 
OPRNF RED RP 


Ow 


NO NH Oe BS Bee wo Hee 


WHITE-PINE BLISTER RUST. 


19 


TaBLE I.—Results of inoculations made on various species and horticultural varieties of 
Ribes, etc.—Continued. 


Species or variety 
and investigators. 


Inocula- 
tions. 


Infe¢-| Num- 


tion. |. ber. 


_SEC. 1.—Species of 
Ribes—Contd. 


Spaulding. .....-. 
R. menziesii: 


R. missouriense: 
IPVOSUMD a = ='=\. 


R. missouriense xX 
reclinatum: 
Gravatt... :-....- 
R. montigenum: 
Spaulding......- 
R. multiflorum: 


Spaulding....... 
R. nevadense: 


Tubeuf 


R. nigrum “‘aconiti- 
folium’’; 


b Slight. 


Ne 


or i) Pee Who bo 


OHHH Be Pe Ore 


ore kK BW 


© 00 No” 


iw 


= 
Re cCtmWWS NER RR wee ee 


Susceptibility. 


eee ceeee 


XXX | XXX 


Species or variety 
and investigators. 


Src. 1.—Species of 
Ribes—Contd. 


R. nigrum “ fascicu- 
latum”’: 


R. nigrum “lacinia- 
tum’’: 


Sorauer-..-- bees 
, R. odoratum: 


R. oxyacanthoides: 
Tubeuf 


Spaulding....... 
Wa ylOl 78,4 - 4.2% -% 
R. parishii: 
Pavdor= - 2% ae 
R. petraeum: 
Gravatt 2. 24°. 
Spauldin 
R. petraeum aitro- 
purpureum: 
Gravatt... a-ak 
R. reclinatum: 
Jaczewski....-.- 


ed on R. aureum: 
Klebahn 
R. reclinatum xX 
missouriense: 
Gravattesede 2s: 


tundifolium: 
Gravattse. 22 ok. 


R. rotundifolium: 
Soravers.. oho oe 


Gravattcn. 4 .o.. 
cpalians meas aN 


Klebahn.. 2)... : 


TVOSULU Dees 4-5 = 
SOraueres-. 2.2 


Tnocula- 


tank Susceptibility. 


In the Out of 


Infec-| Num- green- 


tion. | ber. (ae al doors. 
ae ery A 
i 2 |/Xxx paiee 
i te Piece, ge SO 
25| 29 
6 6 
1] 2\bxx | xx 
3| 3 

ig ho as 
oft ae pee ET oe 
gi) 3g 
Gia 
1 1 sy S| eal Pa aS 
Kick 
2| 2 
7 Tt SCX Sw Se 
| uaclp KPa aa ock 
C} dL pehedeale. 
Aes eee 2 
DRIDY adil gots otiok 
Tid PA ieee ig Viaetea hs Phe aces 
7 baa ih babe tin aa 
TEVA ats Tl baat pe 
ali ss ria 
Pim fib 
1 | is 
ool ON oh cae ognee ac = 
Dsl ting} send TN 
1i|), Oy, pe 
Gh) 2 
2 |. al} Semele. 
ota 
ra Pitas | oes 22 te 
Gh -ghis « See Re 
evi yg 

c0 & ff xx x 
c6| 6 
Gl doranhe ARO. 
fa let aes pole og 
Od 4 eet eeeheey 92 
TGs) aed cheers 
i at 


c Part seedling plants, 


20 


BULLETIN 957, U. S. DEPARTMENT OF AGRICULTURE. 


TABLE I.—Results of inoculations made on various species and horticultural varieties of 
Ribes, etc.—Continued. 


Species or variety 
and investigators. 


SEc. 1.—Species of 
Ribes—Contd. 


were ewe 


R. rubrum pubes- 
cens: 

Spaulding....... 

R. rubrum scandi- 
cum: 


Spaulding and 
Merrill <2 22.3 


Gravatt. .<4:-£.. 
Spaulding.-...... 
gt ar a 
R. sanguineum 
“albidum”’: 
Gravati.. <2 40: 
R. sanguineum 
‘*floro pleno”’: 
Gravatt. icc. .c< 


Spauldin 
R. vulgare macro- 


b Slight, 


Inocula- 
tions. 


Infec- 
tion. 


et et bh 


eH wr 


COM HOF COC Hw Hw 


[Ss re a — i i 


et et bb 


— ae 


Be FPR NHN FPN ee 


Oo mR oO RUT He 


Susceptibility. 
paves: Out of 
fo doors 

ouse 


weet eeee 


Species or variety 
and investigators. 


Inocula- 
tions. 


Infee-| Num- 
: een es 
tion. | ber. Sout a doors. 


SEc. 2.— Varieties of 
Ribes nigrum. 


avons tee oe 
Black Grape: 
Spaulding....... 
Blacksmith: 
Gravatt... --- <2. 
Black Victoria: 


Boskoop: 
Colley, Spauld- 
ing, and Tay- 
TOReoe eae eee 
Carter: 
Grayatt. 2. yes 


Gravatt. /3st.2 28 


Gravatt, M ar - 
shall, Merrill, 
and Spaulding. 


Collins: 
Spaulding....... 
Coronation: 

Gravatt and Taylor. 


thel: 
Spaulding and 
Taylor: 23:22: 
“French Black ”’: 
Gravatt and 
Spaulding..... 


ITY: 
Gravatt. 22655: 


ee: 

Gravatt, Mar- 
shall, and 
Spaulding. .... 
us: 


a : 

Tenn: sgl BE elas | 
Mammoth: 

Gravatt: 222-2. 

Marvel: 
Gravatt, Spaul- 
ding, and Tay- 
Le SAP ge 

Naples: 
Marshall and 
Tevior. <>. bp 2: | 
Norton: / 


Gravyatt:...-...a! 


14 


24 


Susceptibility. 


os Ae Out of 


1:| siete 
ib.o eee 
5 | X Om eae 
‘ 
14,1) xeqtleeieee 
i! X.20l see eee 
3 |. XOkholeeeeee 
a7| xx | Xxx 
s| xx | xx 
4-| -XXead een 
2! xx | Xx 
5|xxx | Xx 
14| xxx | XXX 
21 xx | XxX 
i |. Gen ee 
3 ms } ener ecee 
13| xx | Xx 
2 x seeceees 
4 XXX sseseeee 
2 D4 Sehocne 
4| xx | Xx 
5.|. See meX 
16| xx | XXX 
.5| xxx | xXx 
2| xx_| Xxx 
6 y 4 eenreeee . 
5|xxx | XXX 
1 > enreecervee 


WHITE-PINE BLISTER RUST. 


21 


TaBLE |.—Results of inoculations made on various species and horticultural varieties of 
Ribes, etc.—Continued. 


Species or variety 
and investigators. 


SEC. 2.— Varieties o/| 
Ribes nigrum—Con. 


Ontario: | 
PAL G. Sac a~ nn: 
Saunders: 
Gravatt and 
Spaulding... -.. 
Seabrook: 


Src. 3.— Varieties of 
Ribes vuleare. 


Admirable: 
Spaulding and 
MOL). 
Albert: 
Gravatt 
Marshall....... 
Angers: 
Merrill and 
Spaulding..... 
Bertin: 
Giwatines os4255 


Gravel .oo. ho 5. 
Bonum: 5 
RERANAGL 2 = sods 5. 
Brandenburg: 
Spaulding. -.-..... 
Buddins: 
omavealt-..- 402: 
“ChampagneWhite’’: 
Spaulding....... 
Chautauqua: 
Gravatt 
Marshall... ..... 
Chenonceaux: 


Cherry: 
Marshalls” se 
Comet: 


Crawford: 
WaPavatess cscs... 
Cumberland: 
Gravatt and 
Spaulding. .... 
Dilnot: 


Early Searlet: 
Merrill and 


Spaulding..... 
Slight. 


Inocula- | susceptibility. 
Infec-| Num- In the | out of 
tion. | ber. | 2™©°2- | doors. 

house. 
2 Pl Pea ee 
6] 9] XX | Xxx 
3 SDS p46 sod 
1 if See Tit REP 
at 1 Stele 
- 15 Oe Sl 
1 1 |) Ses OR ae 
1 2 Dd heared dete 
4 TS ale ono 
3 ig ls cy aha eae OP 
3 3 x ae 
2 9 ay Ae Ee 
4 4 x MAY 9153 
eee |! PRT RSENS 
2 a by a Saeh  N 
2 2 4 gael 
i iL x way 
a eae eS xX 
5 5 Seek 
1 als. tae x: 
2 Pais es x 
4 4 Sees ine ree 
if i emit kAbnie 
3 5 St | PA Ee 
2 2 NOON dS fm ag 
5 5 x 0 
3 3 Ver Lie 
6 if x x 
2 Or Sees 


Species or variety 
and investigators. 


tion. 


SEc. 3.— Varieties of 
Ribes vulgare—Con. 


Everybodys: 

ree GAVAGE ota le ee 

“Eyath Nova”’: 

Merrill and 
Spaulding..... 


Gravatt. 2 tee. 
Franco-German:—~ 
Gravatt, Mar- 
shall and 
Spaulding..... 
Frauendort: 
f, Gravatt... 
“Giant Red?’’: 
Gravatt 
Marshall....... 
“Giant White’’: 
Gravattey: 24392 
Goliath: 
Spaulding 


Ny: 
Greenfield: 
Spaulding 


and 


and 


|| ‘Improved Cherry”’’: 


Gravatts face e 
Knight: 

Gravatt, Spaul- 
ding, and Tay- 
fons. AAS 

“Large Red”’: 

Spaulding and 

Mernrnlle =. aca. 


|| ‘Large White”: 


Gravatt-. 2555. 
London: 
Gravatt 
Marshall....... 
“Marvin Crystal”’: 
Rhoads hse lece 
Moore Ruby: 
Gravatt, Hedg- 
cock, and Mar- 
shall iss Se. Jy. 
New Red Dutch: 
Spaulding....... 
North Star: 


ee eee ete eee ee 


Raby Castle: 
Spaulding....... 

Red Dutch: 
Spaulding and 


bo 


i) 


_ Inocula- 
tions. 


ber. 


G6 


Cn 


ao wv 


K eX Cxe’ xX 


= 


OS 


x 


xXx te" XK 


x 


Susceptibility. 


In the 
Infec-|Num- ereen- Out of 


house. 


doors. 


eer ccces 


92 BULLETIN 957, U. S. DEPARTMENT OF AGRICULTURE. 


TABLE |.—Results of inoculations. made on various species and ers varieties of 
Ribes, etc.—Continued. 


Species or variety 
and investigators. 


SEc. 3.— Varieties of 
Ribes vulgare—Con. 


Redpath: 
Spaulding. ...... 
Rivers: 
Gravette... a2 
Sablons: 
Spaulding and 
Pavlos. |. sea. 
Scotch: 
Gravatt, Merrill 
and Spaulding. 
Simcoe King: 
Spaulding. -...-.-. 
- Skinner: 


Striatum: 
Spaulding. - 
Transparent: 
GEAMAU Go ence deer 
Turinoise: 
Gravatt and 


Utrecht: 
Gravattsigeio.e. 
Verrieres: 
Gravatt and 
Spaulding. .... 
Versaillaise: 
Gravatt, Mar- 
shall and 
Spaulding... . 
Victoria: 
Gravatt, Spauld- 
ing and Taylor 
Warner: 
pi ae mee hte oye 


th White Branden- 
burg’’: 
Spaulding pistons 
White Champion: 
(Gravatieneet.o.. 
White Cherry: 
Spaulding. -.-.... 
White Dutch: 
Gravatt and 
Marshall....... 
White Gondouin: 
Gravatt and 
Marshall. 2.2 -.. 
White Grape 
Marshall... 2.2... 
White Imperial: 
Gravatt, Hedg- 
os and Tay- 
‘““White Kaiser’’: 
Spaulding. ...... 
‘CWhite Leviathan’’: 
Gravatt and 


White Pearl: 
Spaulding. 

White Versailles: 
Merrill and 


Wilson: 
Marshall......... 


d Dead spots only. 


Go W 


iw) 


or 


-| Num- 
ber. 


bo 


6 


bo 


ur 


—! 


Susceptibility. 
In the 
green- uae 
house. : 
Orayild's sah OA- 
eT aay es 
De dual aes ee 
RW as cm ae 
Oe id cece 
x x 
Darel eh ree 
x x 
? 
KO enone cts s 
x 0 
KX elle peck ee 
x xx 
x x 
xe oleae nae 
> aia ud CAS 
OK PN EES Sere 
Pinata ply °.4 
On Wares 
DI ies Serta 
Katy lanes 
er oe XK 
x x 
XX x 
rte | Parents Aa eae 
DOE ale Seat oo 
Kee aleccescets 
Og tit ane 
Seine oa x 
+ iEe se x 


Species or variety 
and investigators. 


| Src. 4.— Varieties of 


Ribes reclinatum. 


Sst ; 
paulding. I !. 
Ima: 


Berkeley: 
Gravatt and 
Marshall. ...-. 
Carmen: 


Marshall and 
"TANI ORa sb ae? 
Champion: 
\ Gravatt and 
TayLOLes eee Se 
Chautauqua: 
Spaulding....... 
Columbus: 
Spaulding....... 
Cumberland: 
Gravatt and 


8: 
Gravatt and 
Spaulding..... 


'| Dunean: 


Tee and Tay- 


Gre Se PAS EP 


| Houghton: 


Gravatt and 


Josselyn: 
Spaulding....... 


|| Keepsake: 


Gravatt... 35.52 


Spaulding paapaers 
Mountain: 
Gravatt and 


Pana Sin Se oe 
Pearl: 
Gravatt and 


M: a rshall and 

Spaulding. .... 
Transparent: 

Gravatt and 

Marshall....... 
Triumph: 

Gravatt, Hedg- 
cock and 
Spaulding..... 

Van Fleet: 

Grauatiee ss... 
Victoria: 

Gravatter 2s. 


Whitesmith: 
Gravattleosges22 


o !} F CO WN WN 


Nw = ob Sc 


Tnfec- Num- ‘Tn the Out of 


Susceptibility. 
green- 
house doors. 
i 2 5 
penis (ee yeye 
xX x 
x x 
x XX 
A... hasan see 
anes x 
Key |e eee % 
0 x 
XT 5 eeaaees 
XX | XX 
x x 
x x 
0 | bs 
x x 
Xx x 
UPB i set 8 
x x 
x x 
x xX 
xX x 
x x 
x x 
x x 
x x 
x x 
emia) Heirs ce 
See x 
x Xx 


WHITE-PINE BLISTER RUST. 93 


Recently Thayer (159) and Bunyard (8) have published results 
of their studies of the cultivated red and white currants. They find 
these currants to be of mixed and badly confused parentage, but con- 
clude that certain varieties sprang from each of the three species, 
Ribes vulgare, R. rubrum, and R. petraeum. Many varieties are still 
to be assigned to the proper species; hence, they are grouped in Table I 
under the name R. vulgare, for convenience, as it is yet impossible 
to assign all of them to any species. 

The gooseberries are well known to be in many cases a mixture 
of Ribes reclinatum with several American species or even pure selec- 
tions of American species. For convenience they are grouped under 
the species name, Ff. reclinatum. 


Susceptibility of Ribes Species and Varieties to Cronartium ribicola. 


Estimates of the susceptibility of the various species and varieties . 
of Ribes have been made. (See Table I.) These are based on work 
done in the greenhouse and on results of the experiments out of doors 
on Block Island. These estimates have been made mostly by two- 
persons, so that they are believed to be quite reliable and accurate 
by the standards chosen. The estimates for the inside experiments 
were made entirely independent of those out of doors. The two 
agree surprisingly. They are based on the results of work covering 
several years, but many of the species and varieties have been sub- 
jected to infection but a single year. A few species will be noted 
which have remained immune in our tests. But some of these 
species are known to have become infected elsewhere. This is true 
of Ribes alpinum which is reported to take this disease in Europe, 
although it is entirely resistant in North America (35, 53). Ribes 
imnommatum has been well tested and took the disease only on newly 
_ developed leaves. It is a very resistant species. Ribes sterilis, R. 
tenue and RF. villosum have not yet undergone satisfactory tests, so 
that no conclusive statement concerning them can be made. 

The species of Ribes vary in susceptibility from the extremely 
susceptible Ribes nigrum to the very resistant R. leptanthum. On 
the former are produced the maximum number of uredinia and telia 
of the largest size, while on the latter the minimum number is pro- 
duced and these are poorly’ developed. Ribes alpinum has been 
entirely immune with us, although it takes the disease in Europe. 

The varieties of a cultivated species run fairly true to the species 
asa whole. Some real variation among varieties is believed to depend 
upon their mixed parentage. Many tests were necessarily made when 
the plants were not at the most favorable stage of development for 
the fungus to attack, and it is likely that further tests of aberrant 
varieties may bring most of them back into agreement with the species 
to which they belong. Of the varieties of the cultivated red currants 


24 BULLETIN 957, U. S. DEPARTMENT OF AGRICULTURE. 


which have been tested, the following are nearly immune: Eyath 
Nova, Franco-German, Holland (see also Tubeuf, 174), London, 
Rivers, Simcoe King. That i is, plants tested under éhese names have 
so far shown themselves resistant, but not entirely immune. 

The cultivated gooseberries, varieties of Ribes reclinatum in some 
cases more or less mixed with American species of gooseberries, are 
resistant but occasionally will become infected. 

Resistant species and varieties have been found reacting to the 
fungus and affecting it as follows: 

(1) Decreased number of uredinia and telia. 

(2) Above accompanied bv reduction in size of uredinia and telia with lowered 
viability. 

(3) Small streaks and flecks of dead or dying tissue in infected leaves with 
uredinia and telia. (See Pl. V, fig. 1.) 

(4) Small dead spots formed early with very few or no uredinia and telia. (See 
Pl. V, figs. 3 and 4.) 

This agrees essentially with the results of Stakman (149) with 
Puccima gramins on resistant grains. 


LIFE HISTORY OF CRONARTIUM RIBICOLA. 
The Peridermium Stage on Pines. 


THE INCUBATION PERIOD GN PINES. 


According to European investigators, Cronartium ribicola has an 
indeterminate incubation period between infection of pie and pro- 
duction of «cia. This varies from :about two to four years, and 
possibly much longer. In one of Klebahn’s inoculation experi- 
ments he got pyenial drops on young white pines 11 months after 
the inoculation (71). In another instance, infection probably 
occurred in 1887, pycnia were produced in 1888, and zcia in 1889 
(65). Recently Tubeuf (174) reported the results of successful 
inoculations on Pinus strobus. Inoculations were made on Septem- 
ber 11, 1914; pyenia formed in July, 1915; they were also produced 
in 1916 in May and thereafter; «cia appeared in April, 1917. 

In North America considerable attention has been given to this 
matter. McCubbin (84) first attacked it by extensive studies of 
naturally infected trees. He concluded that five seasons were 
necessary for most of nearly 1,600 infections in Ontario to develop 
mature ecia. He outlines the process as follows: first season, 
infection occurs; second season, dormant; third season, swelling of 
the bark; fourth season, swelling with pyenia; fifth season, mature 
ecia. This makes a lapse of about three years and six months 
between actual infection and the formation of mature #cia. 

Stone (153) in 1917 studied this problem in a locality where the 
fungus was fruiting on white pines for the first time after infection 
occurred. The infection came from Ribes cynosbati, which in 1914 
was heavily infected. The Ribes plants were removed in the spring 


WHITE-PINE BLISTER RUST. 95 


of 1915, so that infection was limited to the season of 1914. Of 40 
infections found, 12 were on 1913 wood and produced ecia in May, 
1917; 28 were on 1914 wood and produced ecia in May, 1917. The 
period of incubation for the former cases could not be more than 
three years and nine months. It may be that infection took place 
on 1-year-old wood, in which case the incubation period would be 
only two years and ten months, as was the case with the 28 infections 
on 1914 wood. 

Study of.infected branches which had just borne ecia for the first 
time was made by Posey and Gravatt in 1917 at Stratham, N. H. 
Their notes show that more than 99 per cent of these infections 
might be 3 years and 6 months old, but could be no older. In 
another locality, they found a number of ecia upon growth of the 
year 1915, making an incubation period of-about 18 months. 

The first successful inoculations of pines with sporidia of Cronartium 
ribicola are apparently those made by Klebahn on August 27, 1903 
(71). Rabes mgrum leaves with telia were placed over two young 
trees of Pinus strobus and the whole covered with bell jars as long as 
the Ribes leaves remained fresh. On June 19, 1904, these trees had 
swollen twigs bearing juvenile leaves. Early in July, pyenial drops 
formed, after a lapse of 10 months. Itis probable that in the normal 
course of events xcia would form the next May. This would make 
an incubation period of about 19 months. 

The writer (133) in November, 1910, inoculated a number of 
. healthy Pinus strobus trees in the greenhouse with teliospores. 
These inoculations were made on the young bark. InJ anuary, 1912, 
one each of those inoculated with wound and without wound of bark 
developed marked swelling. A little later pycnial drops formed, 
but snails ate them and the surrounding bark, so that the infections 
did not develop. Apparently it would have been a matter of but a 
few months when excia would have formed. This would give an 
incubation period of about two years. In May, 1916, the writer (145) 
set out healthy Pinus strobus trees among some experimental Ribes 
bushes on Block Island, R. 1. The Ribes were heavily infected the 
rest of the season. Telia began to form the latter part of July and 
were abundant by September. On May 10, 1918, several of these 
trees were found bearing ecia. This makes a maximum incubation 
period of about 21 months. 

In 1917, 10 young plants of Pinus flexilis were set out in the experi- 
mental plat on Block Island. Nine of them have lived. In the spring 
of 1920 seven of them bore ecia of Cronartium ribicola on the growth 
of 1918, and the other two were much swollen and discolored, so that 
if alive they will certainly produce ewcia in 1921. It appears that P. 
flexilis is very susceptible. The experiments on Block Island indicate 
that it is even more susceptible than is P. strobus. The incubation 


2°26 BULLETIN 957, U. S. DEPARTMENT OF AGRICULTURE. 


period would be about 20 months. A number of P. strobus trees set 
in 1917 also bore «cia in 1920, and many more will do so in 1921. 

Clinton and McCormick (12, 15) found that artificially infected 
trees of Pinus strobus, kept in the greenhouse, developed pyenial 
drops in five to six months after inoculation. 

All of the writer’s experience in various outbreaks of this parasite 
shows that most of the newly formed cia are located on nodes and 
internodes that are 3 years old or over. It is rather exceptional for 
ecia to be borne on needle-bearing wood 2 years old, in which case 
the minimum incubation period is about 18 months. The average 
incubation period out of doors is approximately 3 years and 6 months. 


TIME, PLACE, AND MANNER OF INFECTION OF PINES. 


There is constant danger of infection of pines at any time after 
telia form; that is, after about the 1st of June. The teliospores pro- 
duce sporidia in 6 hours under favorable conditions.6 The sporidia 
germinate immediately. According to Clinton and Miss McCormick, 
infection of pine leaves may take place within 48 hours (14, 15) after 
the germinating sporidia are placed on the leaves. Any period of 
moist weather of 54 hours or longer after about June 1 may cause 
infection of pines. | 

The available evidence indicates that infection of pine twigs takes 
place in or about the bases of the leaf fascicles (71, 84). If this is 
true for most cases, as seems likely, infection of Pinus strobus can 
occur only on wood that is 1 or 2, or exceptionally, 3 or 4 years old. 
This follows from the fact that the needles of this species ordinarily 
live only two seasons, but rather exceptionally they may live three 
or four seasons. 

Tubeuf (174) in 1917 published the results of successful inocula- 
tions with sporidia of Cronartiuwm ribicola on pines. He inoculated 
Pinus strobus, P. lambertiana, P. excelsa, P. parviflora, P. peuce, P. 
cembroides, P. flexilis, P. montezumae, and P. cembra. He got 


yellow spots on the needles of P. lambertiana but no further results - 


were noted. P. strobus became infected readily and bore ecia, but 
none of the other species showed definite signs of infection. Infection~ 
evidently occurred in the needles, many of them having yellow spots. 
They were also present on the stems. Mycelium was abundant in 
the yellow areas. Tubeuf says that infection of the stem from the 
leaves is not common, but that direct infection of the stems is much 
more likely to occur. No pyenia were obtained on leaves, although 
the masses of mycelium in the yellow spots seemed to form the base 
for the pycnial spots in the bark. Older plants of Pinus strobus 
became infected less readily than those only 2 years old. This 


6 York, H.H. Field studies of Cronartium ribicola in the White Mountains of New Hampshire. Seen 
in manuscript. To be published in Phytopathology. 


WHITE-PINE BLISTER RUST. . a 


infection of young plants he attributes to the fact that shoots bearing 
primary (juvenile) leaves go into the winter season with buds at all 
stages of growth, and many are incompletely protected by bud 
scales. Inoculations made on Séptember 11, 1914, with sporidia 
succeeded on the primary leaves, on the secondary (mature) leaves, 
and on the epidermis of growing buds and of young shoots. Yellow 
spots were present on all these parts in the spring of 1915. | 

Clinton and Miss McCormick (12, 14, 15) have recently announced 
successful inoculations in the leaves of Pinus strobus. Studies of 
thousands of infections show that infection takes place through the 
stomata of the pine leaves of all ages. Inside the stoma a sub- 
stomatal vesicle is formed which is of a characteristic shape. Thence 
the mycelium extends into the vascular bundle and then grows rapidly 
downward to the twig. Infection may take place in 48 hours. 
Inoculations on stems did not succeed. Inoculations on opened 
and unopened buds succeeded in a few cases, results being somewhat 
doubtful with the unopened ones. Infections on the leaves become 
visible, about a month after inoculation, as tiny yellowish spots 
centering on the line of stomata on the under side of the leaf. These 
spots turn golden yellow. ‘Similar yellow spots may form on the 
twig after the fungus has become established there. A yellow 
mottling of the infected leaves is the principal symptom of the disease 
at this time. 
- This is rarely noted in nature, but two instances having been seen 
by the writer before 1920 (131, 132, 133, 134). The spots were on 
both leaves and stems of naturally infected Pinus strobus trees. 
Richards has recently found them on naturally infected leaves. 
So far as known they have been mentioned previously only by 
Tubeuf (174); Klebahn (71), who noted them on artificially infected 
trees but failed to designate the point of infection; and by Pechon 
(105), who observed them on naturally infected trees. The writer 
thought the yellow spots resulted from the growth of the fungus out- 
ward from the stem into the leaves. . Klebahn seems to have been 
of the same opinion. It is believed that this happens sometimes. 
In 1920 such spots were seen on pine leaves naturally infected at 
Temple, N. H., and at New Boston, Mass. They are abundant in 
certain localities. Artificial infections have resulted from inocula- 
tions into the bark of the stem by the writer (133). 
_. Cronartium ribicola is able to grow in bark much more than 3 or 
4 years old if it once gains access to the interior. Infections have 

been seen which were still producing «cia on bark up to 35 years 
of age. A common method of infection of pine trunks 20 or more 
years of age is by growth of the mycelium from infected small side 
branches (135). (Pl. II, figs. 1 and 3.) Very often a twig near the 
base of a large branch becomes infected. The disease then extends 


28 BULLETIN 957, U. S. DEPARTMENT OF AGRICULTURE. 


downward into the large branch, and from that into the main trunk 
of a tree, finally girdling it and killing the entire tree. This is true 
of nearly all of the older trees that have been killed in North America. — 


TYPES OF INFECTION ON PINES. 


There may be said to.be three types of infection on white pines 
resulting from natural inoculations. These are (1) direct infection 
of the main trunk on the leader; (2) direct infection of young branches 
or twigs; and (3) infection of an old trunk by spread of the mycelium 
from an infected branch. (Pl. I, figs. 1 and 3.) All of these are 
present in outbreak areas in North America. Direct infection ap- 
parently occurs only on growth not more than 3 years old. Infec- 
tion of large branches or trunks, so far as we can judge, is limited 
only by the thickness of the bark. Old rough heavy bark of Pinus 
strobus was supposed to be immune to attack, but it has become in- 
fected by spread of the mycelium from infected side branches. It 
is a common method of entry of the fungus into older parts of a tree 
which were formerly supposed to be too old to become infected. 
It is very frequent in older outbreaks. This has not been mentioned 
in European literature until 1918 when Fischer (41) called attention 
to it. 


DIAGNOSIS OF BLISTER RUST IN PINE BARK BY MEANS OF THE MYCELIUM. 


In 1916, and to.some extent before that date, when numerous 
specimens of diseased white pines were sent to the Office of Inves- 
tigations in Forest Pathology for quick and reliable diagnosis of the 
blister rust, many specimens were received which bore no fruiting 
bodies of the parasite. The appearance of many of these made it 
practically certain that they were infected with Cronartium ribicola. 
Colley (16, 19) studied the problem and shortly decided that the 
mycelium and the haustoria did ‘furnish reliable evidence for 
identifying this parasite in the bark of Pinus strobus. The large 
intercellular hyphez, the large and abundant haustoria, and their 
manner of attacking the living cells, were found to be entirely differ- 
ent from the characters of any other known parasite of Pinus strobus. 
The use of these characters for four successive seasons with great 
numbers of specimens in various stages of development has indicated 
that such diagnosis of the disease is absolutely reliable. 


LONGEVITY OF THE MYCELIUM IN PINE SLASH. 


In November and December, 1916, some diseased native white 
pines were cut in outbreak areas in Ontario and in Maine, the slash 
being left lying upon the ground. Entirely independent observa- 
tions made by McCubbin in Ontario and by Posey in Maine early in 
May, 1917, showed that new ecia were forming abundantly upon 


Bul. 957, U. S. Dept. of Agriculture. PLATE II. 


— 


——— 


———— 


SECTIONS OF PINE TREES, SHOWING TYPICAL PROGRESS OF BLISTER- 
RUST INFECTION. 


Fic. 1.—Section of the trunk ofa young tree of Pinus strobus, showing entrance of the 
blister rust into the trunk from an earlier infected branch. The dark shading on the 
trunk indicates the visibly infected portion. x1. Drawnby J.M.Shull. Fie. 2.— 
Trunk of young tree of Pinus strobus, about 2 inches in diameter, showing (by zona- 
tion) the progress of the blister rust. The disease entered the trunk from the side 
branch. The cracked bark (c) indicates where ecia have formed; the black spots (6) 
indicate the developing pycnia; the shaded part outside (a) indicates the area where 
the bark is discolored. 4. Drawn by R. H. Colley. Fic. 3—A trunk 8 to 10 
inches in diameter. The disease attacked the swollen twig first, then ran downward 
to the main branch, from which it has spread into the trunk. The latter will soon 
be girdled and the tree will die. Photographed by J. F. Collins. 


wna ste 


WHITE-PINE BLISTER RUST. 29 


the cankers on this slash (89). This overwintering of the fungus 
by means of the mycelium is favored by the slash lying in moist 
places. It was also noted that a piece of a trunk several inches in 
diameter was producing new excia after being kept in the dry air 
of the artificially heated laboratory in Washington about 6 weeks. 
These findings are significant, since they show that the cutting of 
diseased pines, if done in the late fall, winter, or early spring, must 
be accompanied by careful collection and burning of the infected 
slash, if infection of near-by Ribes is to be prevented. This difficulty 
may be obviated by cutting the pines in summer when the following 
hot, dry weather will kill the slash and end the life of the mycelium 
within it. 
SEQUENCE OF PYCNIA AND ECIA AND PROGRESS OF THE DISEASE IN PINE BARK. 


Study of many blister-rust cankers of varying ages in the bark of 
large trunks of pine has shown that the disease extends through the 
bark in a regular and well-defined manner. Cankers of several years’ 
standing usually consist of four distinct zones (20) (Pl. LI, fig. 2): 


(1) An inner central zone of dead rough bark where ecia have been borne in pre- 
ceding seasons. This area often has at its center a dead lateral branch or twig down 
which the disease has traveled from its first place of infection. This is the most com- 
mon method by which infection of large trunks and branches takes place. 

(2) An annual zone of living, swollen bark surrounding the dead area. Here is 
produced the latest crop of ecia. This zone varies in width from a fraction of an inch 
up to several inches. 

(3) A zone of discolored living bark bearing the pycnial spots, drops, or scars. 

(4) An outer zone of living bark, little or not at all swollen, showing a yellowing or 
bronzing of the normal green color of the smooth living white-pine bark. These zones 
of course move steadily outward with the progress of the mycelium. 


This sequence of zones of activity shows that we have a regular 
succession of events, as follows: 

(1) Invasion of healthy bark by the fungous mycelium, resulting in yellowing and 
bronzing of the invaded bark. 

(2) Formation of pycnia in discolored and often Pe ohea. but still living bark. 

(3) Formation of ecia in living bark which has previously borne pyncia. 

(4) Death of the bark which has borne excia in abundance. 

Investigations by Gravatt and Posey, and Colley (20, p. 650-651) 
indicate that the bark is often killed by invading secondary fungi as 
well as by Cronartiwm ribicola itself. Rhoads,’ York,® and Pen- 
nington * found that occasional patches of bark, where ecia have 
been borne the previous year, remain alive and bear a second crop 
of zcia the second season. 


7 Rhoads, A. S. Studies on the rate of growth and behavior of the blister rust on white pine in 1918. 
Seenin manuscript. Published in Phytopathology, v. 10, p. 513-527. 1920. 

8 Yoru, aH. Op. cit. 

° Pennington, L. H. Investigations on the white-pine blister rust in New York. Seen in manuscript. 
To be published as Tech. Bul., N. Y. State Col. Forestry. 


30 BULLETIN 957, U. S. DEPARTMENT OF AGRICULTURE. 


Rhoads *° came to the conclusion that the disease spreads from the 
original point of infection upward and downward at about equal 
rates of progress. Posey and Gravatt, and Rhoads found that it 
spreads at nearly the same rate laterally on both sides. Progress 
upward and downward is usually more rapid than it is sidewise. It 
also appeared that in infections not yet bearing ecia, the point of | 
greatest swelling is where infection first took place and where ecia 
will be first produced. Very often a dead twig or a leaf scar shows 
very plainly the original point of entrance of the fungus to the bark. — 
Rhoads concluded that infections on shaded lower branches do not 
spread as rapidly as those on vigorously growing ones, but Posey and 
Gravatt " find that the former are more likely to be attacked by 
secondary fungi, which soon kill the branches. 

Posey and Gravatt‘! found that there are more or less frequent 
instances in old infected areas of white pines where the infections on 
lateral branches die out. .The statement (131, p. 16; 141, p. 5) that 
trees once infected with this fungus never recover was largely based 
upon studies of trunk infections. Like all rules, it has its exceptions, . 
as here indicated. At Kittery Point, Me., Posey and Gravatt 
studied one of the oldest outbreaks in North America. Trees of all 
ages from a few years up to 50 or 75 were infected. Here it was found 
that secondary fungi often kill the blister rust in an infected branch 
and that increasing suppression of lower branches killed many of the 
infected ones before the blister rust spread to the trunk of the tree. 
It was found that about 15 per cent of all the infected trees in the area 
studied recovered from the disease by the action of these two factors. 


THE PYCNIA AND PYCNOSPORES OF CRONARTIUM RIBICOLA. 


The pycnospores of the Uredinales have received comparatively 
little attention, since it has been generally accepted that they are 
apparently functionless (10, 21, 70, 110, 122, 155). The writer can 
find but little data upon which this idea is based. Plowright (110), 
Thaxter (158), Jaczewski (47), and Klebahn (68) are the only investi- 
gators known to the writer who have actually inoculated plants with 
the pycnospores of their rusts. It seems that the pyenospores should 
be more thoroughly tested. 

The work with pycnospores of Cronartiwm ribicola in Europe seems 
to be limited to that of Klebahn (68), who made inoculations with them 
upon young Pinus strobus trees without infection occurring. Even 
in this case there was not a clear-cut result, such as is to be desired. 
More recently Colley (18) has shown the importance of the pyenial 
spots, drops, and scars as symptoms of the blister rust in pine bark, 
and still more recently (20) he has investigated their morphology and 
cytology. ; 

10 Rhoads, A. S. Op. Cit. % | 


11 Posey, G. B., and Gravatt, G. F. Field studies on the white-pine blister rust at Kittery Point, Me. 
Seen in manuscript. 


WHITE-PINE BLISTER RUST. oi 


GERMINATION OF THE PYCNOSPORES. 


Plowright states that pycnospores (spermatia) of some of the 
Uredinales have been germinated in sugar solutions by Cornu and 
himself (110). Brefeld (7) states that the spermatia of several rusts 
have been germinated in culture solutions. Later Carleton (10) 
stated that he had been able to germinate the pycnospores (sperma- 
tia) in but a single instance. 


The spermatia of Uredo caeoma-nitens Schwein., budded sparingly on May 31, 1893, 
after 24 hours in a dilute solution of honey, but would not germinate in water. 


Still later he said (11): 


‘Until recent years it was not supposed that the spermatia produced regular germ 
tubes, but that the germination is always simply a process of budding. Dr. N. A. 
Cobb and the writer have shown, however, that ordinary germ tubes are produced in 
the germination of these spores as well as in the other spore forms * * *. Spermatia, 
though germinating readily in water, will be found to do much better in a rather 
dilute sugar solution, or perhaps still better in a solution of honey. 

Investigations were made in 1918 by York and Overholts,” who 
tested their germination in water and in various solutions of glucose, 
cane sugar, dextrose, maltose, lactose, peptone, extract of macerated 
Ribes leaves, and extract of macerated pine bark. Fresh pycnospores 
gave no germination. Pycnospores subjected to the cold of an ordi- 
nary refrigerator from 3 to 20 days gave degrees of germination 
increasing with the length of time in cold up to-18 days. Germina- 
tion occurred in 3, 5, and 6 per cent cane sugar and in 3, 6, and 10 
per cent dextrose. The stronger dextrose solutions gave the best 
results. No germination occurred in tap water in any case. 


SEASON OF PRODUCTION OF PYCNIAL SPOTS, DROPS, AND SCARS. 


The dark spots (PI. I, fig. 2, b) which precede the exudation of the 
pycnial drops may be found in the infected bark at all times of the 
year. Records and observations made from 1909 to date furnish 
definite data on the season of pycnial drop formation. (See Table V, 
p. 72.) The pyenial drops are produced immediately after the 
ecial season; that is, from about June 20 until winter. The rusty- 
brown scars left after the disappearance of the drops may be seen 
at all times of the year on old cankers. On new infections the scars, 
of course, do not appear until the drops have formed and disappeared. 
All of these are positive symptoms of this disease in white pines. 


THE ACIA AND JECIOSPORES OF CRONARTIUM RIBICOLA. 
SEASON OF PRODUCTION OF THE ZCIA. 
The zcia develop at varying dates in the same locality in different 


years, according to the season. The locality, whether a warm or 
cold exposure, at a low elevation or a high one, well to the south or 


® York, H. H., and Overholts, L.O. The germination of the pycnospores of Cronartium ribicola. Seen 
in manuscript. To be published in Phytopathology. 


Bg BULLETIN 957, U. S. DEPARTMENT OF AGRICULTURE. 


far north, has much to do with the time that the ecia appear. They 
begin to push through the bark several weeks before they break open 
and distribute the sciospores. Open blisters have been noted as 
early as April 5 in eastern Massachusetts, but they were nearly three - 
weeks later in the Adirondacks the same spring. Table V (p. 72) gives 
specific data so far as they are available for this and related dates. 

Klebahn (68) stated that seciospores are produced by an secium of 
Cronartium ribicola for more than 14 days. Posey and Gravatt ¥ 
found that sciospore production took place at Kittery Point, Me., in 
1917, from April 29 to July 1. 

In the spring of 1918, Rhoads made observations at Kittery Point, 
Me., to determine how long individual ecia produce spores.4 On 
May 3, he stuck pins, bearing numbered pieces of paper, into 300 
gecla on various trees just as they first broke open. On May 20, the 
peridia of all but 63 of the cia were entirely gone with most of the 
spores. On May 29 remnants of but 19 were left and on June 4, 
none. ‘Therefore, in 1918 the zciospore season was about 4 weeks long 
at Kittery Point, Me. 

York ° working at North Conway, N. H., in 1918, found that a few 
individual zcia contain viable spores for from 20 to about 30 days. A 
study of zcial production on single cankers showed that acia matured 
for a period of about 30 days. These infections were all on relatively 
small twigs and branches. On larger branches or trunks the period 
may belonger. Study of the period of ecial production in that entire 
region showed that it was approximately 70 days. At Lewis, N. Y.,%° 
the ecial season in 1919 was slightly more than two months in length. 
After the main excial season, late straggling ecia form. Rhoads * 
noted that xcia occasionally develop on areas of bark which bore 
ecia the preceding year, but which were still alive. 

York noted a newly formed ecium of Crenartium ribicola near 
Littleton, N. H., on July 21, 1918 (179). Several still more remark- 
able cases were noted by York and Ninman at Amery, Wis., on 
September 15 and 16, 1919. Such late ecia appear to be unknown 
for any of the other stem Peridermiums except C. occrdentale, which 
has an ecial season from June to August. Numerous instances are 
known where C. ribicola was entirely absent on Ribes in a given 
locality early in the season, but later was found to be present in greater 
or less abundance. Some of these infections may originate from 
such late ecia. These late eciospores may remain viable over winter 
in the ecia, since Dosdall (29) has found that eciospores occasionally 
retain miata: until’ the next spring. 


13 Posey, G. B., and Gravatt, G. F. Op. cit. 14 York, H.H. Op. cit. 
14 Rhoads, A. S. Op. cit. 16 Pennington, L.H. Op. cit. 


WHITE-PINE BLISTER RUST. 33 


Observations by Pennington * on the zcia showed that more zcia 
were produced per canker and many new cankers were fruiting in 
1919, so that more eciospores were produced that year than in 
1918 in the Adirondacks. Observations on the first generation of 
uredinia and the results of spore-trap work indicated, however, that 
not as Many «ciospores were set free in 1919 as in 1918. This is 
supposed to have been due to heavy rains, which beat them down 
from the air. The distribution of the first generation of uredinia 
showed that the eciospores were as widely disseminated in 1919 as 
in 1918. 

DISTANCE OF DISSEMINATION OF THE ASCIOSPORES. 

As is true of many of the more difficult points in the life history of 
Cronartium ribicola, European statements concerning the distance 
that the xciospores are distributed are based apparently mostly on 
personal opinions. The value to be attached to these statements 
seems to rest on the known excellence, or the reverse, of the pub- 
lished work and judgment of the writer who is being considered. 
European mycologists have mentioned a number of instances where 
this fungus appeared on Ribes which were said to be far removed from 
white pines. But some of these cases were later found to be actually 
much nearer diseased white pines than was at first supposed. Tubeuf 
(166) has stated that the eciospores spread the disease up to 500 
meters or more. On the other hand, a considerable number of 
definite recommendations for separation of the alternate hosts set a 
distance of only 30 to 100 meters (131, p. 41-42). 

In North America earlier field experience indicated that the 
eciospores spread the disease for rather short distances from their 
source. It was recognized from the beginning that these spores are 
exceedingly light and well adapted to wind dispersal, and it was stated 
that our knowledge of their dispersal was very limited. Special 
efforts have been made for three seasons to gather more data on this 
problem. 

Posey, in 1917, set bushes of Ribes nigrum in a salt marsh at Kittery 
Point, Me., at varying distances from infected pines before uredinia 
were formed. Some infection resulted from eciospores upon Ribes 
plants more than a quarter of a mile from any white-pine trees. 
The infecting spores probably traversed several hundred yards addi- 
tional, as the nearest pines were not known to be diseased. The 
heavily infected area was about 14 miles distant, and the infecting 
spores may easily have come that distance. 

Posey also examined the islands of the Isles of Shoals, off Ports- 
mouth, N. H., for the presence of Cronartium ribicola. He found no 
pines, but a number of Ribes hirtellum plants. A few leaves were 


17 Pennington, L. I. Op. cit. 


46103°—21—Bull. 957 3 


o4 BULLETIN 957, U. S. DEPARTMENT OF AGRICULTURE. 


found infected with the fungus. In 1920, Snell reexamined these 
islands much more carefully. He again found the fungus on several 
leaves and decided that it is evidently a case where the xciospores 
were blown from infected pines to the islands. The islands are about 
7 miles from the mainland, so that it appears that the zciospores may 
be blown this distance and infect Ribes. There appeared to be no 
reason for thinking the fungus wintered over. At any rate, it must 
have come from the mainland originally. The islands where the 
disease was found are very seldom visited, so carriage of spores in 
this way appears to be eliminated. 

McCubbin (88) found that the sciospores fall about 8 feet in seven 
minutes in still air. This indicates a very wide potential distribution 
of these spores by a moderate breeze. 

In 1918, York and Overholts (cited in Spaulding, 145) worked in 
the White Mountains of New Hampshire in a generally infected 
region. _Much work was done with spore traps and much time spent 
in examination of Ribes plants which were isolated from white pines. 
The work proved that the zciospores are distributed for miles to the 
tops of adjacent mountains approximately 3,000 feet high, that they 
arrive in a viable condition, and that they are the means by which 
the disease spreads far and wide to Ribes. 

In 1918, also, Pennington and Snell (cited in Spaulding, 145) 
worked in the eastern Adirondack region of New York. Spore traps 
here gave valuable contributory evidence, but study of the distribu- 
tion of the first generation of urediniospores with reference to neigh- 
boring white pines gave the best results. Here it was found that 
spore traps caught sciospores up to 550 feet from any pines. Within 
a large area of cultivated land at Essex, N. Y., an intensive study was 
made by Snell (128) of the first generation of urediniospores. In this 
area the Ribes were found to have first-generation uredinia sparingly 
and widely scattered; that is, the eciospores causing the infection 
evidently came from a considerable distance. In one case diseased 
Ribes were found three-fourths of a mile from any ‘white pine. 
Several others were found at smaller distances from any pine trees. 
It was concluded that the eciospores came from a distance of not less 
than three-fourths of a mile and probably much farther. 

These conclusions concerning the wide spread of xciospores in the 
two localities were arrived at independently and without the knowl- 
edge by either party of what conclusions had been reached by the other. 

In 1919, Snell (128) found near Rush Lake, Minn., infections on 
Ribes leaves which were 114 miles from the nearest pine and about 
3 miles from the nearest known diseased pine. Many such infections 
were found in the same general area which were half a mile or more 
from any pine. These infections were found developing when the 
first generation of uredinia appeared throughout that general in- 


WHITE-PINE BLISTER RUST. 85 


fected area. They must have been produced by eciospores which 
had been blown at least the above distances. 

In 1919, York caught and germinated zciospores on the summits 
of two mountains nearly 4,300 feet above the adjoining lowlands. 
It is evident that altitudes such as this do not prevent the spread 
of this fungus. Pennington * caught xciospores up to 1,200 feet 
distant from pines and found diseased Ribes three-fourths of a mile 
from any pine tree. 


AGENTS DISSEMINATING THE ACIOSPORES. 


It has been evident from the beginning that wind is a most efficient 
and active agent in the distribution of the spores of Cronartvum 
ribicola. While the probability of spore carriage by other agents 
such as insects and the larger animals was recognized, no time could 
be spared for work upon it. More recently, Gravatt and Marshall 
(45) and Gravatt and Posey (46) have made some studies of this 
sort. 

Gravatt and Marshall worked in the experimental greenhouse 
where no xcia were present. They found that pycnia and the 
surrounding bark tissues were eaten by sow bugs. 

Gravatt and Posey (46) made studies in the field in a heavily 
infected pine area at Kittery Point, Me. Here it was found that 

-gipsy-moth larve, which were abundant, fed eagerly on the 
pyenia and excia of the blister rust and also ate the bark tissues 
immediately adjacent to them. It was found that in some cankers 
a considerable percentage of the fruiting ecia were thus destroyed. 
But a few ingested spores remained viable, as tests in hanging drop 
cells m tap water yielded a few germinations. These larve also 
were carriers of abundant sciospores on their bodies, many being of a 
decided yellow color from the spores with which they were dusted. 
The gipsy-moth larve are known to have been blown 20 miles or 

more. Within the gipsy-moth infested area these larve are then 
dangerous agents in the distant spread of the disease, a fact not 
previously appreciated. 

Notes made by Gravatt show that a wood mouse caught in the out- 
break area at Kittery Point, Me., carried a small number of eciospores 
on its body. While squirrels, other animals, and birds have not been 
examined, there can be no doubt that they are active carriers of the 
spores. It is known that the eciospores become attached readily 
to clothing, and there can be no doubt that persons may carry the 
disease, at least locally, in this manner. 

‘ In anumber of outbreak areas where pine infections were just about 

_ to produce pycnia for the first time, it was noted by several observers *° 


18 Pennington, L.H. Op. cit. 
19 Rhoads, A. S. Op. cit. 


36 BULLETIN 957, U. S. DEPARTMENT OF AGRICULTURE. 


(143, 144) that squirrels ate the swollen bark from the infected parts 
of the branches. (Pl. III.) They undoubtedly run over fruiting 
cankers and pick up eciospores on their fur and feet. Porcupines 
may act in the same manner. Birds undoubtedly carry these spores 
to some extent, and as in the ecial season they begin nesting and 
largely remain in the same locality they, too, act only as local carriers. 

Some indications have been noted where a road traverses a narrow 
valley, or a narrow clearing in a forest, that automobiles create drafts 
which carry spores to some distance along the highway. It seems 
entirely possible for steam trains and electric cars to do the same 
thing. 

POSSIBLE AUTGCISM OF THE ASCIOSPORES. 

The possible autcecism of the xciospores of Oronartium ribicola has 
been considered. As early as 1913 field observations were made with 
this point in view, but no evidence of the spread of the fungus directly 
from pine to pine was found. 

The question whether eciospores of other stem-inhabiting pine 
Peridermiums are capable of infecting pines has received considerable 
attention. In 1907 Liro (82) stited’ that he had made 169 inocula- 
tions of Pinus sylvestris with eciospores of Peridermium pin from 
the same host. No infections resulted. In 1914 Haack (48) stated 
that he had made similar inoculations and obtained abundant infec- 
tions. His experiments were performed out of doors, with no pro- 
tection from natural infection and with trees which already were 
naturally infected; hence, his results are worthless. In 1913 Meinecke 
(95) made successful inoculations with zciospores of “ Peradermiaum 
harknessw”’ upon Pinus radiata under controlled conditions. Later 
(96) he changed the name of the fungus to Peridermium cerebrum and 
reported that he had successfully inoculated Pinus radiata with 
eciospores from P. radiata and from P. attenuata; and P. muricata 
with seciospores of P. cerebrum from P. radiata. | 

In 1915 -Hedgcock (51) successfully inoculated trees of Pinus 
ponderosa var. scopulorum, P. contoria, P. sabiniana, P. carvbaea, 
P. mariana, P. pinea, and. P. halepensis with eciospores of “ Peri- 
dermium harknessii” from P. contorta. He has also successfully 
inoculated P. ponderosa and P. virginiana with eciospores of “ P. 
harknessw”’ from P. ponderosa. 

In 1918 Klebahn (73) published the results of sibbeherele: inocu- 
lations made by him with eciospores of Peridermium pint upon 
young twigs of Pinus sylvestris, both with and without wounds, 
under controlled conditions. These results throw doubt on the 
strict hetercecism of the eciospores of all the stem-inhabiting pine 
Peridermiums. 

The following tests have been made with the xciospores of Cro- 
nartium ribicola: Klebahn (68, 70) repeatedly inoculated young 


Bul. 957, U. S. Dept. of Agriculture. PLATE III. 


TRUNK AND BRANCHES OF PINUS STROBUS, SHOWING BARK INFECTIONS OF 
BLISTER RUST EATEN BY SQUIRRELS. 


Photographed by W..H. Snell. 


Fic. 1.—An infected branch which was evidently a young infection that had not yet formed 
ecia. Fic. 2.—Infected bark of living tree. Here may be seen the blister-bearing central 
area at the base of the branches in place, while the outer, surrounding, pycnial zone has 
been eaten away. Fic. 3.—Infected bark of living tree. The eaten parts were where pycnia 
were forming. 


2 


Bil 957 UE Ss. Dept. of Agriculture. PLATE lV 


LEAVES OF RIBES INFECTED WITH CRONARTIUM RIBICOLA, SHOWING DIFFERENT 
TYPES OF ATTACK. 


Fic. 1.—Lower surface of aleaf of Ribes aureum infected by Cronartium ribicola. Note the charac- 
teristic isolated infected areas, with the abundant uredinia closely crowded together. Fig. 2.—A 
Ribes bud with a single leaf which bears normal uredinia. This leaf is relatively old, being 
stunted in growth by adverse conditions which have held it stationary for several weeks. Fie. 3— 
Lower surface of an infected leaf of Ribes vulgare, horticultural variety White Transparent. Note 
the large infected areas merging into a single one. The uredinia are not so closely crowded 
together as in figure 1. Fic. 4.—Lower surface of an infected leaf of Ribes nigrum. Note the 
general distribution of the telia, their grouping closely together, and their vigor of growth. 


WHITE-PINE BLISTER RUST. 87 


Pinus strobus trees with eciospores, but without producing infection. 
Hennings (53) inoculated P. strobus trees with xciospores and also 
with teliospores. No infection resulted from either. In the spring 
of 1916 the writer made 100 inoculations with wounds into the bark 
of Pinus strobus trees, out of doors, with fresh eciospores of Cronar- 
tium ribicola. No infections have resulted to date. In May, 1917, 
the writer (146) inoculated white pines by dipping the tips of young 
twigs in water containing great quantities of newly formed eciospores 
of OC. ribicola. The needles as well as the twigs were covered with 
spores. Glassine bags, containing wet wads of cotton, were then 
tied over the inoculated twigs to keep up the humidity of the air. 
No evidence of infection is yet visible. 


GERMINATION OF THE ®CIOSPORES. 


Experience shows that fresh xciospores taken from ecia just as 
they are about to break open, or just at the time of breaking, possess 
maximum infective power. Doran (28) confirms this opinion. 
Inoculations made with such spores are sure of results if conditions 
are at all favorable. Older exciospores are erratic in germination, 
but some of them retain viability to a marked degree. Cooling on 
ice stimulates their germination to a decided degree, as is shown by 
experiments performed by Eriksson (32), Gravatt, and others. 
Each spore produces from one to five (20, 29) germ tubes, which 
branch freely. The viability of fresh xciospores is generally high, 
as many as 95 per cent germinating under favorable conditions. 
They require 8 to 10 hours to germinate (28). 

Doran (28) determined the minimum, optimum, and maximum 
temperatures for the eciospores of Cronartium ribicola. Five series 
of tests were made. It was found that germination in distilled-water, 
drop cultures occurred through a range of 12° C., but the percentage 
of germination dropped rapidly both above and below the optimum. 
The minimum temperature for the zecjospores was 5° C., the optimum 
was 12° C., and the maximum was 19° C. 


LONGEVITY OF THE ACIOSPORES. 


Klebahn (70, p. 26) seems to have been the only European investi- 
gator who has tested the longevity of wciospores. He found them 
strongly viable after seven weeks. 

From the beginning of the work of the writer on Cronartium 
ribicola it has been known that the xciospores retain their viability 
for a relatively long time under favorable conditions. In 1910 a 
single zeciospore which had been kept in the laboratory for more 
than five months in an open ecium on a diseased young tree which 
was dried and kept as a specimen germinated in water (131, p. 30). 
In 1915 McCubbin (85) collected on May 6 a diseased young white 


38 BULLETIN 957, U. S. DEPARTMENT OF AGRICULTURE. 

pine bearing ecia. It was placed in a box in the laboratory and 
allowed to dry out. Tests were made by inoculating leaves of Ribes 
nigrum plants on May 7, May 21, June 4, and June 23. On the last 
date no infection occurred. In 1916, McCubbin repeated these 
experiments and found that the exciospores remained capable of 
infection under the conditions of his experiment at least 39 days. 
He believes they may retain viability considerably longer, as his 
tests were conducted under adverse conditions. 

‘Kciospores collected on April 9, 1917, and kept in a age glass 
vial were tested by Gravatt weekly in hanging drops of distilled water. 
They gave good germination for about one month, then weakened 
until Tate 9, when the last germination occurred. The tests con- 
tinued until ails 14. On May 7, 1917, another series of similar tests 
was started by Gravatt and Taylor. (See Table II.) The eciospores 
were placed in two glass vials with cheesecloth tied over the tops. 
One vial (B) was kept out of doors on a window sill on the north 
side of a building where the sun did not shine. The other vial (A) 
was kept in a dark refrigerator. The spores were tested weekly in 
distilled water. In most cases the cultures were placed in an ice 
box for about 12 hours. The spores kept in the ice box retained 
their color throughout, while those on the window sill had faded 
perceptibly by June 16. Lot A varied in germination from 8 per 
cent at first to 3 per cent on June 2. Germination persisted until 
July 2, when the last occurred in this lot. Lot B germinated freely 
until May 26 and not at all after June 23. Cooling and darkness in 
this case decidedly stimulated germination for one month and pro- 
longed viability about 10 days after the uncooled xciospores which 
were exposed to light had lost all viability. 


TABLE II. —Longevity of the spores of Cronartium ribicola. 


Germination (per cent). 
Lot A, vialin Lot B, vial out of 
Date refrigerator. : doors. 
1917. Notes. 
ZEcio- wre Telio- | AXcio- pgs Telio- 
SPOFES. | snores, Spores. | SPOTES. | Horas, | Spores 
Mayo S:in <s 13 90. 8 8 85 
May. 22 38 10 85 1 10 90 
May 19.| 5 60 80 2 40 85 
May , 26.|. 4 45 70 3 37 50 Not cooled in refrigerator before germination. 
June 2.) 3 6 40 .8 .8 10 Do. 
Tune. 00) 1 .65 51.3 wl 1.5 4.4 
June 16. La 1, 35 4.5 0 0 0 Lot A somewhat faded. 
June 23.) 0 0 3. 5 . 05 0 0 Lot A much faded. 
July 2. 05 0 5 0 Ah Piet gt A Teliospores in lot A mouldy. 
July Fel OD 0 0 0 OI ee ae 
July 14.) 0 0 0 0 OF getes ties Oe on and urediniospores mouldy in 
lot color of lot B still fairly good. 


eee. 


WHITE-PINE BLISTER RUST. 39 


In April, 1918, Dosdall tested in distilled water Gn hanging-drop 
cultures) the viability of wxciospores produced in 1917 (29). On 
April 19, 1918, a dead white-pine branch bearing a canker which 
had fruited in 1917 was collected at Rush Lake, Minn. While new 
ecia were just beginning to break open on other cankers at this 
time, the spores tested were not new ones, as they were dug from the 
bottoms of 1917 cavities after scraping off the outer exposed spores. 
Nor could there have been new excia pushing up beneath the old 
ones, as the branch was dead. It was found that from 1 to 2 per 
cent of the spores germinated in distilled water, each spore producing 
from 3 to 5 germ tubes. It is barely possible that these spores 
were from an abnormally late ecium (179) and therefore were not so 
old as Dosdall supposed them to be. Even so, they must have been 
approximately 6 months old. 

This experiment of Dosdall has been repeated. A dead branch 
bearing zcia of 1918 was collected at Kittery Point, Me., on Febru- 
ary 25, 1919, and taken to Washington, D. C. Taylor tested the 
zeciospores by hanging-drop cultures in tap water, but no germina- 
tion of the spores could be demonstrated. Spores of other fungi 
were present and did germinate. 

York ”° collected a specimen of diseased white pine bearmg newly 
formed xcia on April 30, 1918. This was put in a paper bag and left — 
in the laboratory away from direct sunlight until October 5, 1918. 
He then broke open a still unbroken ecium which had not pushed 
through the outer bark and made cultures of the spores. He got 
some germination in tap water under these condition 157 days after 
collection of the material. The spores were still yellow when the 
test was made. Spores from excia which had broken open did not 


germinate. 


During the season of 1918, Pennington *! found that in the Adiron- 
dacks the xciospores remained viable for at least four weeks after 
being removed from the ecia and stored in a dry place. The same 
season, York found that in the White Mountains eciospores from 
blisters in cankers cut from the tree and kept in the shade out of 
doors remained viable for 75 days, as shown by tap-water cultures 
and inoculations on Ribes leaves. 

In 1919, Pennington *! found that xciospores, whether brought 
into the laboratory or left in the field soon lost their viability, less 
than 1 in 400 germinating after three weeks from the breaking open 
of the ecium producing them. ‘Tests upon the viability of eciospores 
after they had been exposed to direct sunlight showed a decrease of 
50 to 75 per cent in viability after three hours’ exposure. After 
an exposure of eight hours, some of the eciospores (1 in 1,500 or 
2,000) were still viable. 


2 York, H.H. Op. cit. 
21 Pennington, L.H. Op. cit. 


40 BULLETIN 957, U. S. DEPARTMENT OF AGRICULTURE. 


Doran (28), in 1919, found that the eciospores germinate well in 
distilled-water drop cultures for four weeks, when germination 
weakens. Germination ceased after six weeks. He does not give 
details of the conditions of storage of the spores. 

Pennington * compared the number of szciospores caught in spore 
traps with the number of infections on Ribes leaves and estimated 
that under the most favorable conditions 1 spore in every 25 which 
lodged upon a Ribes leaf produced infection there. An estimate 
for the season showed that not more than 1 in 100 produced infection. 


The Cronartium Stage on Ribes. 
THE INCUBATION PERIOD ON RIBES. 


The length of the incubation period between infection of Ribes 
by vseciospores ‘and urediniospores of Cronartvum ribicola and the 
production of mature uredinia or telia varies greatly, according to 
the external conditions of temperature and moisture and the age 
and condition of the leaves infected. Examination of the records 
of 493 inoculation tests made in the greenhouse show that the shortest 
incubation period between infection and formation of mature uredinia 
is practically 7 days. These records show that 2.4 per cent of the 
cases fruited in 7 days, a like number in 8 days, 7.3 per cent in 9 
days, 10.4 per cent in 10 days, 20.8 per cent in 11 days, and 19.7 
per cent in 12 days. The percentage rapidly drops after this to 9.7 
per cent in 13 days, 8.1 per cent in 14 days, 8.5 per cent in 15 days, 
8.1 per cent in 16 days, and 3.2 per cent in 17 days. 

Pennington ” found that the incubation period on Ribes in the 
eastern Adirondack region with both eciospores and urediniospores 
was 11 to 18 days; it was usually 13 to 15 in mature leaves and some- 
what longer in leaves which were very young when inoculated. 

There are times when the fungus produces only uredinia in the 
greenhouse as well as in the fields. The behavior of the fungus is 
not entirely controlled by weather conditions, but is greatly influ- 
enced by the condition of the host leaves. At other times the 
fungus will produce nothing but telia. At such times telia are pro- 
duced in a very short time after infection. Telia have been obtained 
in 9 or 10 days after infection. From 12 days upward they may be 
formed at almost any time up to 2 or 3 months after infection. 

York” in many cases has obtained telia directly from zeciospore as 
well as urediniospore inoculations upon overmature ** leaves. 

22 Pennington, L.H. Op. cit. 
23 York, H. HH. Op. cit. 
24 The term ‘‘overmature”’ is here used to denote that stage of development of Ribes leaves where they 


have become tough, leathery in texture, and of maximum thickness, but have not begun to decline in 
photosynthetic activity. 


WHITE-PINE BLISTER RUST. 41 
METHODS OF INOCULATING RIBES. 


The methods of inoculating Ribes plants are not claimed to be 
original with the writer or his associates. It is well known that 
some of these methods have been in use for many years. They are 
given here to show the conditions under which the experimental 
work was done, as follows: 


(1) When plenty of spore material is available, as is usually the case with ecio- 
spores, the spores may be placed in a considerable quantity of water and the top or 
branch of the Ribes plant dipped into it. The spores will be distributed quite 
evenly over all parts of the dipped plant. (See Clinton (12).) This method was used 
by the writer as early as 1909, and has been very successful. It uses up large 
quantities of inoculum, however. 

(2) Another method which has been much used is to spray water from an atomizer 
upon the part to be inoculated, then shake the dry spores upon the wet surface. 
This also requires a plentiful supply of inoculum. It has been a favorite method, 
as it gives good results with reasonable certainty. 

(3) When inoculating with urediniospores from fresh leaves, the part to be inocu- 
lated is sprayed, and the leaf bearing the inoculum is turned with its lower surface 
on that of the healthy leaf and the two rubbed lightly together. . 

(4) If the inoculum is scanty, the spores are moistened with a drop of water and 
lightly scraped off upon the moistened healthy leaf with a sterilized scalpel or knife 
blade. 

(5) If the inoculum is in moderate quantity, the spores are placed in a small 
quantity of water in a sterilized atomizer and sprayed upon the healthy plant. 

(6) The spores, if fairly plentiful, are sometimes collected in a watch glass, a small 
quantity of water added, and then a clean camel’s-hair brush is dipped into the 
mixture and brushed over the surface to be inoculated. With this method it is 
advisable to wet the inoculated part with an atomizer after inoculation, or results 
will be meager. 

(7) Occasionally healthy leaves have been rubbed or dipped in the spore mixture 
described in paragraph 6. 


Gravatt made comparative tests of some of the foregoing methods 
of applying the inoculum. This comparison showed one-fourth 
more infection with method 5 than with method 6, with three 
different species of Ribes. General experience has shown the order 
of efficiency of the methods to be as follows: 1, 5, 2, 6,3, 7,4. This 
is probably largely due to the greater number of spores used by the 
more successful methods. All will give good results when the 
relative number of spores used is considered. 

With all these different methods of applying spores and moisture, 
it is essential to supply all the-water possible without having it 
form large drops and run off. 

As a supplement to the local moistening, it is necessary to keep 
the inoculated plant in a moist chamber for 12 to 24 hours. In the 
experiments by the writer and his associates the preferred method 
has been to keep the plant in the moist chamber 48 hours. 

The matter of a proper moist chamber is a problem of considerable 
moment. Glass bell jars are good, but costly and easily broken. 
A tightly closed wooden and glass chamber of considerable size was 


42 BULLETIN 957, U. S. DEPARTMENT OF AGRICULTURE. 


tried, but is unsatisfactory because the tender leaves of the inoculated 
plants are liable to scald in hot weather. Hunt (57) tested a form 
of the iceless refrigerator for this purpose. This is a modification 
of the field moist chamber described by Keitt (61, p. 540-541), 
without a continuous water spray. It is essentially a framework 
large enough to receive several potted plants, on top of which a large 
pan of water is placed. Around the framework is fitted a loose 
curtain of heavy cheesecloth completely surrounding the framework 
on the sides and extending from the water in the pan on top to the 
ground. In use, the cloth is wet thoroughly and the water in the 
pan keeps it wet. This keeps the air within the chamber saturated 
with moisture and cool, which is the desired condition for the plant. 
This has been very successful even in the hottest summer weather ~ 
and has the desirable qualities of durability, cheapness, portability, 
and simplicity. 

Clinton (12) has recently reported the successful inoculation of 
plucked leaves of Ribes in moist chambers. This is an old method 
with the rusts, and was used by Barclay in India as early as 1887 (4). 
Clinton has apparently developed this method to a point of maximum 
efficiency. It has not been used in the investigations by the writer 
and his associates, the preferred method being to retain natural 
conditions as far as possible in making susceptibility tests. 


FACTORS CONTROLLING THE INFECTION OF RIBES. 


Among the factors controlling infection of Ribes by Cronartium 
ribicola may be mentioned moisture, sunlight, age of leaves inocu- 
lated, and age of inoculum. wort 

Frequent allusions are made by investigators to the need for 
abundant moisture in producing the infection of Ribes by ecio- 
spores and urediniospores of Cronartuum ribicola and in spreading 
the fungus on Ribes. 

In 1904, Aderhold (1) performed a series of experiments to deter- 
mine the influence of moisture upon the infection of Ribes vulgare 
by eciospores of Cronartium ribicola. He had two inclosed cells, 
the air in one of which was moistened by artificial rain, while in the 
other it was kept relatively dry; he had similarly arranged plats 
open to the free air. The conditions in these cells and plats he 
summarized, as in Table III. 


Taste III.—Conditions in cells and plats of Aderhold’s experiments. 


— 


Experiment. Air. Temperature. . Moisture. of ight 
}.. Raim calle ooo Motionless.........-.- High. .......-c:cccenec| VOry gt@us su eseneneeee Small. 
20) Dry. cell JUNE BO Ix COLLEEN dk ee Very high.) 2053215928 Slight .8. XC). “PQeRE SLE Do. 
3. Open rain plat..... MOwING f 206 Jo. sew en ae Below normal......... Great. <0: eee oe Great. 
4. Open dry plat.....|....- Got. Sree es Normal?) . Ye. -S2e8 Normal . 22EtEy: 0 Do 


WHITE-PINE BLISTER RUST. . 48 


Aderhold placed his experimental plants in these cells and plats 
on April 16. On May 6 all of the plants were heavily dusted with 
zeciospores, and half of those in each cell and plat were put under 
conditions opposite to those they were in before inoculation. The 
plants from the closed rain cell when inoculated and replaced in the 
same cell took the disease heavily. Those from the closed dry cell 
when inoculated and placed in the closed rain cell also took the 
disease heavily. Those transferred from both, the rain and dry 
cells to the dry after inoculation showed no infection. All the plants 
kept in the open plats failed to take the disease. It is apparent 
from his results that infection depends upon an atmosphere that is. 
nearly saturated with moisture. 

Experience in the greenhouse has shown that it is necessary to 
have abundant moisture on the leaf surface for infection to succeed. 
The leaf itself must be wet, without having large drops of water 
collect. This moisture must be retained for some time by keeping 
the surrounding air saturated with water vapor. Gravatt made a 
series of parallel tests, part of the inoculated plants being kept under 
bell jars 2 hours, part of them 7 hours, and another part 24 hours. 
Infection occurred with the 7-hour and the 24-hour plants, but not 
with the 2-hour tests. The writer made a series of inoculations in 
the greenhouse with xciospores without putting the plants in moist 
chambers. Not one infection resulted within 14 days, the usual 
time necessary to reach full fruiting condition. The plants were 
then put into moist chambers for 48 hours, and fair infection resulted 
. from the spores put on the leaves 14 days before. LEwert (87) per- 
forméd a similar experiment in 1912 with the same results, as did 
Werth (177) in 1915 and York” in 1919. McCubbin in 1916 inocu- 
lated two leaves on each of seven shoots of a Ribes nigrum plant. 
Two of the shoots were put in a moist chamber for 48 hours. The 
remaining five shoots were left uncovered. The leaves of only the 
two inclosed shoots developed infection. 

It is equally necessary to have plentiful moisture for infection to 
occur out of doors. Hennings (53) found a severe outbreak of the 
disease on Ribes during a dry time in the Dahlem Botanical Garden, 
but he attributes the intensity of the attack to the daily watering 
(sprinkling) of the bushes. Ewert (85) says, ‘‘In the summer of 
1902, moisture, the important factor for infection, was not lacking, 
so all conditions were favorable for the spread of the Cronartium.”’ 
Schellenberg (123) attempted to inoculate Ribes bushes with ecio- 
spores from Pinus cembra in the open air. He attributes his failure 
to produce infections to the bright sunny weather prevailing at the 
time. In 1910, the writer (131) inoculated Ribes leaves with fresh 


% York, H.H. Op. cit. . 


44 BULLETIN 957, U. S. DEPARTMENT OF AGRICULTURE. 


zeclospores out of doors. The leaves were not wet, but there was 
dew every night. No infection resulted. 

In 1913, Stewart and Rankin (151) made some observations on 
this: problem. On May 14 two white-pine trees were found bearing 
abundant open ecia. On May 17, they were cut down and burned. 
About 120 feet from the pines there was a small plantation of Ribes 
nigrum and f. vulgare. The weather was dry and unfavorable for 
infection of the currants to take place for several days before May 
15. The forenoon of May 15 was damp, but in the afternoon it 
dried off and remained dry until after the trees were destroyed. 
They concluded that the infection of Ribes which developed on June 
10 apparently could have taken place only in the wet forenoon of 
May 15. It appears to the writer that the long incubation period 
indicates that the spores from the pines stuck to the Ribes leaves 
without germinating until a later rainy period long enough for 
infection to occur. 

Studies made by Pennington?* and Snell (145) in New York in 
1918 on Rrbes rotundifolium show the absolute dependence of the 
spread of this fungus upon moist weather. They found that six — 
distinct generations of urediniospores were produced during the 
season, with a slight seventh one the last of the summer. These 
appeared approximately two weeks after spells of rainy weather. 
York working in the White Mountain region for three years has 
made a great many successful field inoculations on various species 
of Ribes without using any form of moist chamber. His work was 
largely carried on, however, in localities naturally moist. 

Temperature also is an important factor. Probably much of the 
efficiency of Hunt’s iceless refrigerator inoculating chamber is due 
to the rather low temperature obtained. Cronartium ribicola is 
favored by low temperatures, as is shown by the optimum tempera- 
tures determined for it by Doran (28). Doran also inoculated plants 
of Ribes which were then kept at 3°, 12°, and about 22° C. No 
infection occurred on the first and last, while the one at 12° C. devel- 
oped uredinia. 

Sunshine is an important factor, indirectly if not directly. Its 
direct influence upon the spores is destructive (30, 88) but it is doubt- 
ful if this action is powerful enough to hinder germination greatly 
if sufficient moisture is present. Indirectly sunshine affects in- 
fection by quickly reducing moisture. It seems that a moderately 
cool temperature is most favorable and that bright sunlight may 
elevate the temperature above the optimum for the fungus. 

The size of the leaves alone seems to have little or no influence 
upon their susceptibility to infection (147). Leaves as small as 


26 Pennington, L.H. Op. cit. 


WHITE-PINE BLISTER RUST. 45 


4 mm. wide have been found bearing groups of uredinia (Pl. IV, 
fig. 2). 

The age and relative maturity of the leaf has much to do with its 
- susceptibility. It has been the general experience that Ribes leaves 
may be overmature and also may be too young to take the disease. 
Infection does not occur on the leaves of a given species of Ribes 
until they have reached a certain degree. of maturity. Leaves 
produced by buds developing in late summer or fall, even if very 
small, readily become infected. The different species of Ribes vary 
much in this regard. Ribes nigrum shows a great range in its age 
of susceptibility, while resistant species become infected only on 
leaves of a certain maturity. The most favorable stage of growth 
_seems to be about when the leaf attains full size but has not become 
hardened and leathery as it does later. Tests were made by Gravatt 
in 1915 in the greenhouse on Ribus nigrum. The plant had three 
shoots of nearly equal size and development. They bore fully 
mature leaves at the base and had leaves at the tips about half 
grown. In this case all the leaves became infected except the lower 
three or four on each shoot. In 1916, McCubbin (ms. report) made 
several series of inoculations with sciospores upon fibes ngrum 
leaves of various ages. The plants were not kept under the best 
growing conditions, so the results are less pronounced than might 
otherwise be expected. He produced no infection on the youngest 
leaves. The older ones took the disease, but the overmature ones 
took it least of all. York®’ made greenhouse tests with plants of 
Ribes mgrum, R. triste, R. glandulosum, R. hirtellum, and R. lacustre. 
Leaves of various ages were present on all the plants. The mature 
ones showed infection first. The degree of infection was heaviest 
on the first species and decreased in the order named, R. lacustre 
having but two pustules on a single leaf. Later, the half-mature 
leaves of R. nigrum and the leaves of R. triste and R. glandulosum . 
two-thirds mature became infected. The younger leaves did not 
become infected then, but when reinoculated later they took the 
disease, except that those of R. lacustre remained healthy. In most 
inoculation tests made by the writer and his associates in the green- 
house both the oldest and the youngest leaves remained free from 
disease, although they were treated gxactly like the others. York 2 
tested this point extensively in the open in 1918 and found that 
leaves just unfolding were almost invariably immune to the fungus; 
older ones took the disease readily; and overmature ones (especially 
late in the season) were immune. Pennington ** reached similar 
conclusions working independently. 


27 York, H. H. Op. cit. 
28 Pennington, L.H. Op. cit. 


46 BULLETIN 957, U. S. DEPARTMENT OF AGRICULTURE. 


Snell * made inoculations out of doors with spores from unopened 
zecia on April 30, 1918. He inoculated opening buds of Ribes glandu- 
losum by carefully inserting a knife so as not to injure the leaflets and 
inserting the spores between the folds of the leaves. The largest 
leaves were 3 cm. broad, the smallest 3 to 5 mm. long. It was very 
rainy, so there was plenty of moisture. No infection was visible on 
May 15, but on May 22 heavy infection was present on all the leaves 
inoculated. The leaves on this date ranged from nearly full size to 
those just opening. The infection was heaviest on the largest leaves 
inoculated and decreased to a light infection on the smallest. The 
check plants were healthy. There are two possible factors which 
might have delayed the infection a week longer than usual. These 
are cool temperature and the immaturity of the leaves. The experi- 
ence of the writer leads to the belief that the latter was the principal 
factor involved in this case. Later Snell found natural infection on 
leaves of Ribes vulgare that were only 12 mm. wide. 

It has been noted repeatedly that the earliest infections on Ribes 
leaves in the spring are about a month later than the time when the 
first eeciospores are set free. It is a question whether this is due to 
very cool nights or to the immaturity of the Ribes leaves at this time. 
Noninfection of immature leaves in the greenhouse leads the writer 
to suspect that the latter is the main factor involved. European 
writers (63, 101) have stated that Cronartiwm ribicola is decidedly 
earlier than the native pine-stem Peridermiums. 

Observations made by Gravatt at Block Island show that new in- 
fection in midsummer was present upon the fifth to the eighth leaves 
from the tip, not counting those less than 5 mm. wide; that is, on 
leaves just mature but not hardened. 

Gravatt and York and Overholts made many inoculations of 
leaves, petioles, and stems with wounds, but found no evidence that 
infection was favored by wounds. 

Whether viability of spores of Cronartium ribicola in culture solu- 
tions, water, etc., is a reliable index of their infective power (48) is a 
question which has arisen more or less insistently since inoculation 
experiments began. Klebahn (70) made a definite test with refer- 
ence to this question with xciospores of Cronartiwm ribicola. The 
spores were collected on March 20 and kept dry until May 8 when the 
test was made. Some were sown on the leaves of Ribes aureum, some 
were sown on a cover glass coated with a thin layer of sterile Ribes- 
decoction agar, and others were sown on a cover glass moistened with 
water. The cover glasses were kept in a moist chamber to prevent 
drying. The Ribes plants became infected after 12 days on every 
leaf inoculated. The spores on Ribes-decoction agar germinated 


29 Snell, W. H. Period of exposure and size of Ribes leaves infected by the blister-rust fungus. Seen in 
manuscript. To be published in Phytopathology. 


WHITE-PINE BLISTER RUST. 47 


slowly at first, but later developed strong germ tubes in considerable 
quantity. Scarcely a spore in water germinated. As a result of his 
extensive experience with the rusts, Klebahn says: 

. in other words, I believe it possible for spores which do not germinate in 
water to infect leaves of the host plant, and it seems to me to be expedient to distin- 
guish between “infection power” and “viability” of spores more sharply than is 
ordinarily done. 

Gravatt had experiences somewhat similar to the above in his in- 
oculations with urediniospores of Cronartium ribicola in 1917. So 
pronounced has been our general experience in this regard, that many 
germination and longevity culture tests made in 1918 and 1919 were 
duplicated by check inoculations on favorable hosts so far as possible. 


LOCATION OF THE INFECTIONS ON RIBES PLANTS. 


SORI ON THE LEAVES. 


The usual place for uredinia and telia of Cronartiwm ribicola to 
form is on the lower side of the Ribes leaf blade. It is rather excep- 
tional for them to appear elsewhere. Nevertheless, they are occa- 
sionally found on the upper side of the leaf blade. They have been 
noted there by Gravatt in the greenhouse and by several out-of- 
door workers on Block Island. The following species have been seen 
with uredinia or telia on the upper leaf surface: Ribes alpestre, R. 
aureum, Rh. cereum, R. fascoculatum, R. fontenayense, R. hirtellum, 
R. odoratum,* and also the horticultural varieties R. aureum var. 
Utah Yellow and R. vulgare var. White Imperial. It must not be 
concluded that because fruiting bodies are found on the upper surface 
of leaves that the infection took place there. On the contrary, in 
every case seen, it was very evident that the fungus had attacked 
the infected leaf beneath, and the attack had been so intensive that 
some sori were pushed through to the upper surface. There never 
were aS many sori on the upper surface as there were on the lower 
one, nor were they so old. 

Some inoculations have been made in Europe to determine if infec- 
tion may take place on the upper surface of Ribes leaves. So far 
as known to the writer they are here summarized: 

In 1913 Ewert (37) brought four potted plants of Ribes nigrum 
into the greenhouse. On April 10 he inoculated the leaves of one 
branch of plant 1 on the lower surface only with fresh xciospores. 
The plant was inclosed in a glass cylinder as a moist chamber. 
Another branch was used as a check. On April 28 the inoculated 
branch bore uredinia upon 11 leaves. On April 15 he inoculated 
the leaves of a third branch, but did not inclose it in a moist chamber. 
On April 26 there was no sign of infection, and it was then inclosed 
in a moist chamber. On May 20 all the inoculated leaves bore 
uredinia. ‘The control remained healthy. 


48 BULLETIN 957, U. S. DEPARTMENT OF AGRICULTURE. 


Plant 2 was treated exactly like plant 1 except that the inoculations 
were made on the upper sides of the leaves. No infection resulted. 

Plant 3, on April 10 and 15, was inoculated on one branch on only © 
the lower surfaces of the leaves. Another branch was inoculated on 
the upper surfaces only. A third branch was left as a check. Weak 
infection resulted on the first branch. A repetition on April 29 with 
fresh seciospores gave better results. 

Plant 4, left untreated, was in another inclosure of the greenhouse. 
It rawivfaied healthy, suai that infection had not occurred before 
the plants were brought into thie house. 

On May 26 similar inoculations were made by Ewert with uredinio- 
spores on the upper sides and lower sides of leaves. Infection 
resulted in the latter case and also a slight infection of the lower 
surface of one leaf which was inoculated on the upper surface. 

Another similar series of inoculations made by Ewert on June 6 
gave infection only on the leaves inoculated on the lower side. He 
fails to say in all cases that the sori formed only on the lower surface 
of the leaves, but his language implies that this is the case. Attack- 
ing the problem in another way, Ewert (37) sprayed Rabes nigrum, R. 
aureum, and &. rubrum, leaves, part on the lower side only, part on 
the upper side only, and part on both sides, while controls were left 
unsprayed. The details are presented on pages 77 to 79. Because 
some leaves which were sprayed on the upper side developed a few 
sori beneath, he appears to be a little doubtful whether infection 
may occur on the upper surface, but he concludes that it ‘apparently 
almost exclusively takes place on the lower surface of the leaf.” 

The writer and his associates have made hundreds of inoculations 
on the upper surface of leaves of many species and varieties of Ribes, 
without a single direct infection occurring there. Numerous in- 
stances have been noted in these experiments in which infection ap- 
peared on the lower surfaces of leaves that had been inoculated on 
the upper side. ‘This is believed to be due to spores reaching the 
lower surface in some unknown way. In fact it is very difficult if 
not impossible to guard against this. York and Overholts inoculated 
leaves of Ribes glandulosum on the upper side, both with and without 
ring cells, to prevent the spores reaching the lower surface. Slight 
infection occurred on the lower side in some cases where cells were 
not used. Where the cells were used no infection occurred. These 
tests were made on leaves of different ages on plants of various ages, 
from young seedlings up to fruiting bushes. Tubeuf (173) inoculated 
leaves of Ribes nigrum on the upper side by applying the spores in 
water with a brush. All of the leaves thus inoculated remained 
healthy except a single one which had a uredinium on the lower sur- 
face. He was uncertain whether a spore infected it through the lower 
surface or through a lesion on the upper surface. 


WHITE-PINE BLISTER RUST. 49 


SORI ON COTYLEDONS. 


The cotyledons of young Ribes seedlings are apparently quite sus- 
ceptible to infection by sciospores and urediniospores of Cronartwwm 
ribicola. Relatively heavy infection has resulted from inoculations 
on the lower surface of cotyledons of Ribes americanum, R. missouri- 
ense, R. oxyacanthoidses, R. rotundifolium, R. glandulosum, and R. 
fasciculatum seedlings in the greenhouse and on RP. glandulosum in the 


field. 


SORI ON FLORAL BRACTS AND BUD SCALES. 


Infection was secured by Gravatt from inoculations of the floral 
bracts of Ribes aureum in several different cases in the greenhouse. 

Infection of opening buds and of bud scales merits more investiga- 
tion. .McCubbin (85) suggested the possibility of infection of partially 
open buds in the fall and the overwintering of the fungus, but he 
could not prove that it occurs. Infection of young leaves scarcely 
out of the bud occurs, but it seems to be limited to leaves that are 
relatively mature, though small. (See discussion on pp. 44 to 46.) 
Search for infections of buds on heavily infected Ribes nigrum bushes 
failed to reveal any infections (151, p.44). Gravatt made inoculations 
of buds about to open, but with no success. York * has inoculated 

successfully an inner bud scale of Ribes nigrum. 


SORI ON PETIOLES. 


Next in frequency to infection of the lower surface of the leaf 
blade is infection of petioles. The first published account of this, 
so far as the writer knows, was given in 1912 (133, 134, 135) and 1913. 
At that time it was considered to be very uncommon. Since than 
a considerable number of such cases have been noted both in the 
greenhouse and out of doors. The following species have developed 
uredinia or telia, or both, upon petioles, as many as 25 or more 
petioles on a single plant being thus attacked: Ribes americanum, 
R. aureum, R. bracteosum, R. cereum, R. culverwellir, R. cynosbati, 
R. dwaricatum, R. erythrocarpum, R. fasciculatum, R. giraldi, R. 
glandulosum, R. wnerme, R. lacustre, R. nevadense, R. nigrum, R. 
parish, R. petracum, R. robustum, R. setosum. The following 
cultivated varieties have had petiolar attacks: Ribes nigrum hort. 
vars. Black Victoria, Climax, and Seabrook Black; R. reclinatum 
hort. vars. Berkeley, Golden Prolific, Poorman, Transparent, and 
Van Fleet; R. vulgare hort. var. White Imperial. Some 10 or 12 
as yet unidentified species collected by Beattie in the Rocky Mountain 
and Pacific coast regions have exhibited the same phenomenon. 


_ York, H.H. Op. cit. 
46103°—21—Bull. 9574 


50 BULLETIN 957, U. S. DEPARTMENT OF AGRICULTURE. 


In many cases the petiole became diseased by growth of the 
mycelium downward from the leaf blade into it, but direct infection 
of the petiole occurs occasionally. This is shown by the presence 
of infections on the petiole one-half inch or more distant from other 
infections. Microscopic examination by Colley in such instances 
has shown the intervening tissues to be entirely free from migrating 
mycelium. York * had several instances where infection took place 
well down on the petiole, and no other infection was present either 
on that petiole or the leaf blade. While many inoculations of petioles 
have been made by members of the Office of Investigations in Forest 
Pathology, but few have been successful, as above indicated. 


SORI ON STEMS. 


Evidence of infection of Ribes stems has long been sought. In 
1917, Posey, Gravatt, and Colley (112) discovered three uredinia 
on young stems of Ribes hirtellum which resulted from natural in- 
fection in an outbreak area. Artificial inoculations on young stems 
of the same species with eciospores produced 18 more uredinia. A 
single stem infection was produced by Gravatt in the greenhouse 
upon a young seedling of R. fasciculatum (Pl. V, fig. 2). AXciospores 
were used in this case also. While the tender stem was completely 
girdled, it survived long enough to form wood and finally completely 
outgrew the disease. Since then Taylor has successfully inoculated 
with eciospores the stems of young seedlings of Ribes missouriense 
and of R. americanum in the greenhouse. York has infected stems 
of young R. glandulosum plants with zciospores and urediniospores 
out of doors, and has found natural infections on the same species 
and on R. cynosbati. He has infected a young stem of a 2-year-old 
plant of R. cynosbati with zciospores in the greenhouse. 


RELATION OF STOMATA TO THE INFECTION OF RIBES. 


A number of investigators of the Uredinales have stated that 
eciospore and urediniospore germ tubes obtain entrance to their 
hosts through the stomata (34, 70, 110, 149, 171). | 

As heretofore stated, Cronartium ribicola infects the Ribes plant 
on the lower side of the leaf mostly. Less frequently it infects the 
petioles, floral bracts, and cotyledons. It may infect young stems. 
Infection never occurs on the upper surface of the leaf. Examina- 
tion of a number of different species of Ribes has been made by mem- 
bers of the Office of Investigations in Forest Pathology. Data on 
the stomata may be summed up as follows: 


Stomata were present in large numbers on the lower surface of leaves of all species 
examined. Stomata were present in small numbers on the upper surface of leaves of 
Ribes cereum (60,78), R. inebrians (60, 78), R. odoratum by Marshall, R. orientale (160), and 


31 York, H. H. Op. cit, 


PLATE V. 


Bul. 957, U. S. Dept. of Agriculture. 


"Tings “W ‘f AC 
poyaivd ‘Onsst} Jve[ poxjovy}e Jo Yywop UL aSejs poouvape atom Y “JUBISISAL oyINy “Nene AJOLIBA [BIN] MOT.LOY, ‘avDh7Na saqry 0 cn palbatt 
jo douj.Uns eddy —"F ‘DIY ‘pvap ApBor[V onsst JvaT “Ue SI[Sol o1mmb st siggy, “Wyrug Ajoliva [vanyynNor}LoYy WWNYDUAJIIL SOQUT jo [wo] pa}oojut 
UB JO dOVJINS Joddq—‘e ‘DI ‘SeLodsotow’ YIM WOTBPNOOUT JO INST Vv SV p/OIgUd UNYADUOKG AG PajoojpUT W94Is WIA wnyoynavswL saqrey ite) ued 
SUTL PIS —"GZ OLA “AUSSTL J Bel 9} Jo Sa1Ap Jo advys A[IVY  °)7002G1.4 UNYLDUOLD Aq po}oojut yoqgsouha saquy ‘JO Jeol BJO goRyINsS yadd qQ—'T ‘OTT 


‘Y1IODISIN WAILYYNOYD JO SNOILOSSN| DNIMOHS ‘Sadly JO LNVId GNV SSAV3)] 


€ 


§ 09 2Ua0H ¥ 


WHITE-PINE BLISTER RUST. 51 


R. vulgare by Marshall. None were found by Unger (176) on the upper surface of 
leaves of R. alpinum nor by Taylor on R. americanum, R. aureum, R. carrvervi, R. 
culverwellii, R. fasciculatum, R. nigrum, R. reclinatum, R. speciosum, and R. (tenut- 
florum) aureum. Stomata were found only on the lower surface of cotyledons of R. 
fasciculatum and R. missouriense, the only ones examined by Taylor. Stomata were 
found by Taylor to be not uncommon on petioles of R. americanum, R. aureum, FR. 
carrierti, R. culverwelli, R. hirtellum, R. inerme, R. nigrum, R. odoratum, R. reclina- 
tum, R. sanguineum, R. speciosum, R. succirubrum, R. (tenwiflorum) aureum, and R. 
vulgare. None were found on petiolesof R. curvatumand R. fasciculatum. Janczewski 
(60) states that stomata are present on the young stems of KR. petraeum. A few stomata 
were found on young stems of R. aureum, R. hirtellum, R. nigrum, R. odoratum, R. 
reclinatum, R. succirubrum, R. (tenuiflorum) aureum, and R. vulgare. None were found 
on the stems of R. carrierii and R. fasciculatum. These findings compare well with 
the inoculation results, if stomata are the avenue for infection. It is perhaps to be 
expected that infection may be produced on the upper surface of the leaves, but only 
very rarely. Colley (20) found young uredinia forming in the substomatal spaces, 
which would indicate that infection took place in that vicinity and presumably 
through the stomata. York * found germ tubes of eciospores entering the stomata of 
leaves of Ribes cynosbati, R. glandulosum, and R. nigrum. 


VARIATIONS IN APPEARANCE ON RIBES LEAVES. 


The study of great numbers of Ribes leaves infected in the green- 
house and of very numerous specimens of diseased leaves collected 
in the field from Maine to Minnesota, during the past ten years, has 
revealed some distinct variations in the appearance of the fungus 
and of the diseased leaves of different species and varieties of Ribes. 
Previous study of such differences seem to have been made chiefly 
by Hennings (52, 53). 


BLISTERY APPEARANCE OF THE UREDINIA. | 


In August, 1916, there occurred a very hot, dry period in New 
England. This was followed by the finding of a few very peculiar- 
looking uredinia on Ribes nugrum and R&R. vulgare. Under a hand lens, 
the uredinia were not of the usual mealy appearance, but looked more 
like tiny blisters. Examination showed that the epidermis of the 
leaves had become toughened, so that the uredinia did not burst 
through it, as they usually do, but pulled it loose from the inner leaf 
tissues and in this way actually formed small blisters. The uredinio- 
spores never broke through it. From the weather conditions pre- 
ceding and at the time this occurred it is believed that the dry, hot 
weather rendered the epidermis tougher than usual. It is a rare 
occurrence, as only a few cases have been noted. In 1916, one speci- 
men came from. each of the States of Massachusetts, Masses and Ver- 
mont. In 1917, a single case was found in New oamipsh ints Hedg- 
cock noted this in 1919 upon artificially inoculated Ribes bushes on 
Block Island. Recently, blisters have been noted on R. auruem and 
R. fasciculatum in the greenhouse. 


3% York, H.H. Op. cit. 


52 BULLETIN 957, U. S. DEPARTMENT OF AGRICULTURE. 
DISTRIBUTION AND SIZE OF THE SORI AND COLONIES. 


It has been found that Cronartiwm ribicola forms its uredinia and 
telia upon each species of Ribes in a manner which in general is 
characteristic of that host species (Pls. IV; V, figs. 1,3,and 4; and VI). 
This was noted in 1902 by Hennings (52, 53), who described some of 
the more striking variations. Like all general statements, the fol- 
lowing are subject to individual variations from the normal or average 


condition for the host species. A statement by Hennings (52, p. 130) | 


indicates the degree of variation discernible to a keen observer: 


It is especially noticeable that the fungus, according to the character of the leaves 
of various species of Ribes, shows great variations in the form and color of the spots 
produced on the leaves, the form and size of the sori, and the size of the telial colu- 


mellz, so that a new observer would assume that several of the fungus forms were 


specifically distinct. 


In general, on species which are closely related, or which closely 
resemble each other, the fungus behaves in a similar manner. Some 
of the more striking variations are described as follows: 


RipesiA.**—Ribes petraeum and var. atropurpureum: Sori close together and evenly 


distributed over the spots; spots large, soon overrunning a large part of the leaf — 


surface. 

Ribes rubrum vars. petrowalskyanum, pubescens, and sibirica: Very scant 
sori, located beside large veins of leaf; var. scandicum has abundant sori, close 
together, generally distributed. 

Ribes triste: Sori clustered on definite spots; spots small, widely separated. 

Ribes vulgare: Sori not plentiful, clustered on spots; spots small and isolated 
(Pl. IV, fig. 3; V. fig. 4). 

HERITIERA.—Ribes coloradense: Sori thickly clustered on diffuse spots. 

Ribes glandulosum: Sori usually thinly scattered over large diffuse spots or 
entire leaf surface, telia very slender and long (PI. VI, fig. 1). | 

Ribes erythrocarpum: Sori plentiful, clustered. 

CaLoBoTrRyA.—Ribes glutinosum: Sori thickly clustered in local areas. 
Ribes nevadense: Sori thickly grouped on local spots; spots large and distinct. 
Ribes viscosissimum:; Sori isolated, scattered over entire leaf surface. 
SyMpHocaLyx.—Ribes aurewm and vars. tenuiflorum and palmatum: Sori abundant, 
closely grouped in rather distinct spots which usually are well separated from 
each other (PI. IV, fig. 1). 

Ribes odoratum: Sori abundant, closely grouped in spots usually well sepa- 
rated from each other. 

AROPHYLLUM.—Ribes cereum: Sori clustered on definite rounded spots which soon 
die. 

Ribes inebrians: Sori on rounded spots. 

EucorEosMA.—Ribes americanum: Sori sparse and scattered, on small irregular spots 
' which redden and die; heavy infection rare; telia short, one-half to 1 mm. 


Ribes bracteosum: Sori plentiful, on large diffused spots or patches of leaf - 


surface. 

Ribes nigrum (Pl. IV, fig. 4) and vars. aconitifolium, fasciculatum, “folio 
argentea”’: Sori crowded densely, often over entire leaf surface, Wiporeass telia 
abundant, reaching 2 mm. in length. 

Ribes viburnifolvum: Sori scant, dead spots form early. 


33 The species of Ribes are grouped according to the arrangement of Janczewski (60). 


WHITE-PINE BLISTER RUST. 58 


GROSSULARIOIDES.—Ribes lacustre: Dead spots formed early on infected leaves; 
sori sparse or diffuse, irregular spots; telia rather scattered. 

GrossuLARrIA.—Ribes lobbii: Sori thickly crowded on rounded spots, telia well de- 
veloped. 

Ribes menziesii: Sori sparse on small irregular spots. 

Ribes speciosum: Sori seated closely together on large rounded spots, telia 

rather short. , 

EuGRossuLaria.—Rhibes alpestre: Sori thickly crowded on large rounded spots, 
telia short. 

Ribes curvatum: Sori crowded on rounded spots on young leaves, on irregular 
spots on old leaves; telia quite plentiful; spots with reddened edges late in 
season. 

Ribes cynosbati: Sori plentiful on definite spots, which are usually rounded 
(Pl. V, fig. 1): spots sometimes wedge shaped, lying between two branching 
veins of the leaf; telia crowded in small groups, 1 to 14 mm. long, rarely over 
entire leaf surface. 

Ribes divaricatum: Sori scattered on rounded spots. 

Ribes missouriense: Sori crowded on rounded indefinite spots on young leaves, 
densely crowded on small leaves, dead irregular spots on old leaves. 

Ribes leptanthum: Sori very scant; dead spots appear so early that uredinia 
can form with difficulty, often only one uredinium on a spot, many spots with- 
out sori; produces the least sori of any species yet noted. 

Ribes hirtellum: Sori usually crowded thickly on small spots; uredinia on 
small rounded spots; telia small, crowded densely; on older leaves, on small 
indefinite, irregular spots bounded by veinlets; spots sometimes purplish on 
the edges. 

Ribes oxyacanthoides: Like R. hirteiluim. 

Ribes reclinatum: Sori rather sparse, on small irregular spots of dead tissue. 
There is a tendency toward a reddening or purpling of the edges of the spots 
on old leaves. (PI. V, fig. 3.) 

Ribes rotundifolium: Sori crowded on small irregular spots. The spots die 
early and are likely to become reddish around the edges even on rather young 
leaves. It is rather rare for the entire leaf to become covered with sori. 

Ribes setosum: Much like R. cynosbatt. 

Hemisotrya.—hibes fasciculatum vars. chinense and japonicum: Sori densely 
crowded on large rounded spots. 
Diacantua.—hibes diacantha; Sori on rounded spots. 
Ribes giraldu: Sori scattered on rounded spots. 


In general, it may be said that R. nigrum and its varieties is the 
optimum host species among the Ribes for Cronartium ribicola. 
Ribes aurewm and R. odoratum and their varieties are perhaps next 
to &. mgrum in favoring the growth of the fungus. R. reclinatum 
does not take the disease readily, but is‘by no means immune to it. 
In fact, no species or variety yet fully tested is entirely immune. 
R. leptanthum probably produces fewer sori for the extent of infection 
than any other species. This is caused by the very early death of 
the infected tissue. 


PALE COLOR OF INFECTED SPOTS ON THE LOWER SURFACE OF RIBES LEAVES. 


The production of sori on an infected spot on the lower surface of 
Ribes leaves is often preceded for one, two, or three days by a pale 


54 BULLETIN 957, U. S. DEPARTMENT OF AGRICULTURE. 


coloration (Pl. VI, fig. 2). This is most likely to occur on young 
leaves. It is a fairly certain symptom of a successful inoculation. 

Striking cases of the preservation of the normal green color in the 
infected areas, while the rest of the leaf is etiolated, have been noted 
a number of times. 


PALE COLOR OF INFECTED SPOTS ON THE UPPER SURFACE OF RIBES LEAVES. 


Numerous young Ribes leaves inoculated in the greenhouse devel- 
oped pale spots on the upper side of the infected leaves (Pl. V, fig. 1). 
These varied from nearly white to yellow. Similar spots are often seen 
in the field. Some species of Ribes seem to be more likely to develop 
these spots than others. Among those showing this etiolation as a 
result of infection by Cronartium ribicola may be mentioned: Ribes 
aureum and its varieties, R. cerewm, R. cynosbati, R. divaricatum, R. 
erythrocarpum, Rk. fasciculatum, R. glandulosum, R. hartellum, R. 
inebrians, R. wmerme, RB. leptanthum, R. nevadense, R. nigrum, R. 
odoratum, R. reclinatum, R. rotundifolium, R. setosum, R. speciosum, 
R. triste, and R. vulgare. These spots seem to be produced by condi- 
tions existing in the immature Ribes leaf when attacked by the 
fungus very actively. 


REDDENING OF INFECTED SPOTS ON RIBES LEAVES. 


Certain species of Ribes react to infection by Cronartium ribicola 
by a reddish or purplish coloration around the edges of the infection. 
This is common with some species, while others apparently must 
have the leaves at a certain stage of maturity for this coloration to 
occur. Ribes americanum, R. curvatum, R. rotundifolium, R. viburni- 
folium, R. glandulosum (old thick leaves), RB. cynosbate (old thick 
leaves), R. hirtellum (old thick leaves), R. oxyacanthoides, R. reclina- 
tum, and R. missourvense develop the red color in the order named. 


DEAD AREAS OF INFECTED LEAF TISSUE. 


Where the attack of Cronartwum ribicola is intense, areas of the 
oldest infected tissue of the diseased leaves collapse and die (Pl. V, 
fios.3 and 4; Pl. VI, fig. 3). The different species of Ribes vary much 
in this bans some developing dead spots very quickly and some 
doing so only after considerable time. zbes nigrum usually resists 
death tenaciously. When a spot dies it is commonly a large one and 
soon results in the premature fall of the affected leaf: At the other 
extreme is R. leptanthum. With this species the infected spots die 
very quickly, even before uredinia can form (147). Less than 10 per 
cent of these spots produce any uredinia or telia, and those few spots 
bearing sori usually have only from one to several stunted sori. All 
species of Ribes tested have sooner or later developed dead spots. 
Just how much secondary fungi contribute to the killing of host 
tissues 1s entirely unknown. 


Bul. 957, U. S. Dept. of Agriculture. PLATE VI. 


LEAVES OF RIBES INFECTED WITH CRONARTIUM RIBICOLA, SHOWING DIFFERENT 
TYPES OF INFECTION. 


Fic. 1.—Infected leaves of Ribes glandulosum, showing lower surfaces; the sparsely scattered telia 
are well distributed over the entire surface. Etiolation caused by the disease is also evident. 
x 3. Fic. 2.—Lower surfaces of leaves of Ribes sp., showing etiolated spots where infection has 
taken place, two days before uredinia were formed. x 8. Fic. 3.—Lower surfaces of infected 
leaves of Ribes aureum, showing the disease distributed in local spots mostly well separated from 
one another. On the right side of the right leafa large area of leaf tissue has died. Etiolation 
from the disease is evident. &. 


WHITE-PINE BLISTER RUST. 55 


THE UREDINIA AND UREDINIOSPORES. 


GENERATIONS OF UREDINIA. 


In 1918, Pennington * and Snell investigated the number of genera- 
tions of uredinia of Oronartium ribicola produced in the Adirondack 
region, and the weather conditions that might influence their pro- 
duction. Ribes rotundifolium, R. cynosbatr, and R. glandulosum 
were the principal species used in these investigations. The observa- 
tions were made in four different localities within 10 miles of the 
town of Lewis. There were seven periods of uredinial production in 
1918. The first generation began on May 28, reached its climax 
about June 12, and then gradually fell off until June 26 to 28, when 
the second appeared. The third began to appear about July 12 and 
reached its maximum on July 19 to 22. The second and third crops 
of uredinia were located almost entirely on those leaves which were 
originally infected by zeciospores or those adjacent to them. Drought 
from July 18 to July 28 caused most of the infected leaves to drop 
from the bushes of Ribes cynosbati and R. rotundzfolvum, leaving them 
partly or entirely defoliated. The fourth crop was much smaller, 
but well marked, and came on August 19 and 20. The fifth genera- 
tion came on September 12 to 15; it would have been more abundant 
had not a heavy frost on September 11 killed all the leaves of R. 
glandulosum and some on the other two species of Ribes. The sixth 
crop appeared especially on the second crop of leaves of the earlier 
defoliated bushes and on fresh green leaves of bushes in sheltered 
situations. The seventh generation appeared on October 15 to 18 
on leaves ready to fall. A study of the weather conditions, as noted 
at Lewis, showed that about two weeks before the appearance of each 
new generation there was a period of at least 24 hours of rainy and 
cloudy weather. But not all such periods were fgllowed by new 
crops of urediniospores. 

In 1919, Pennington®™ found that the generations of uredinia were 
not as distinct at Lewis, N. Y., as they were in 1918. The first four, 
on May 23, June 21 and 22, July 3, and July 20, respectively, were 
well defined. A fifth on August 7 and a sixth on August 21 were 
distinct on some bushes, but in most places overlapped. In general, 
after August 1, the generations overlapped, because of rain every 
day or two, so as to become confused with each other. 


SEASON OF PRODUCTION OF THE UREDINIA. 


Like the ecial season, the beginning of the uredinial season of pro- 
duction varies with conditions somewhat, though to a less marked 
degree. May 16 is the earliest recorded date for mature uredinia. 
A week after this is the more usual time for them to be found in most 


8¢ Pennington, L.H. Op. cit. 


56 BULLETIN 957, U. S.. DEPARTMENT OF AGRICULTURE. 


localities. (For range of observed dates in various sections of North 
America, see Table V, p. 72.) 

In the White Mountain region of New Hampshire, York ** found 
fresh urediniospores in 1918 on May 16 and as late as November 17. 
Urediniospore production there continued on Some bushes for 185 
days, while under average conditions it continued about 120 days. 
At this place the following species were under observation: Ribes 
cynosbati, R. glandulosum, R. lacustre, R. nigrum, R. odoratum, R. 
oxyacanthoides, Rk. reclinatum, R. triste, and R. vulgare. Uredini- 
ospore production continued the longest time (185 days) on R. nigrum 
and the shortest time (65 days) on R. lacustre. In general, it can | 
be stated that the urediniospores continue to form as long as there 
are susceptible leaves on the Ribes bushes of a given locality. 

York * found that the maximum urediniospore production in 1918 
occurred about July 14 to 16 and in 1919 about July 25 to 26. After 
these dates came the maximum sporidia production, and then the 
bushes became almost completely defoliated. | | 


DISTANCE OF DISSEMINATION OF THE UREDINIOSPORES. 


In the early work upon Cronartium ribicola in North America the’ 
wide dissemination of the fungus from a given center appeared ‘to 
take place by means of the urediniospores. Stewart and Rankin 
(151), who had an especially good opportunity to study this point, 
concluded that the urediniospores were blown at least one-half mile. 
Early general observations of the spread of this stage indicated that 
a wet season greatly favored it, while a dry season just as markedly 
retarded it. 

McCubbin (87) found that urediniospores fall in still air about 8 
feet in 5 minutes. He calculated that a 30-mile breeze would carry 
them 24 miles in this time. Theoretically they may be distributed 
long distances if located on a hill or if picked up by convection air 
currents. But. most of these spores are actually produced within 2 
feet of the ground in most localities, so that they are not picked up’ 
by the wind as readily as the eciospores, which are commonly pro- 
duced a number of feet above the ground. When set free, the 
urediniospores adhere in masses, so that they are not as readily 
blown by the wind as are the xciospores, which tend to fall apart: 
when dislodged from the zcium. 

York and Overholts (cited in Spaulding, 145) in 1918 at North 
Conway, N.H., found urediniospores in spore traps up to 300 yards 
distant from the known source. This was where rain was plentiful 
practically all summer. Observations on infections of Ribes glandu- 
losum and R. cynosbati plants indicated that the disease spread by » 
urediniospores up to 100 yards. In some cases where the bushes 


8% York, H.H. Op. cit. 


WHITE-PINE BLISTER RUST. 57 


were protected by surrounding trees or other objects, the rust spread 
little or not at all. In other words, where moisture was plentiful 
through the season, the distance of spread by urediniospores was 
governed by factors controlling the free access of the wind. In 
Essex County, N. Y., drought prevailed through July and August 
in 1918. Here Pennington * worked with spore traps and Snell (128) 
gave special attention to a study of the spread of the uredinial stage 
on Ribes. The Ribes of this section were largely Ribes rotundifolium | 
and R. glandulosum. Here the rust spread in most instances only 
to adjacent leaves from those first infected on a given bush. The 
spore traps here caught urediniospores only at a very short distance, 
50 feet or less. 

In 1919, York (cited in Spaulding, 146) caught urediniospores up 
to a distance of 3,400 feet in an open location, but they did not 
germinate. Urediniospores caught at 3,200 feet did germinate. 
Pennington ** caught urediniospores up to 156 feet. 


AGENTS DISSEMINATING THE UREDINIOSPORES. 


Wind has been supposed to be the principal agent distributing 
the urediniospores of Cronartwum ribicola. While this supposition is 
correct in the main, other agents are concerned in the matter. 

Hennings (53) says that sprinkling diseased Ribes plants with a 
strong stream of water carries urediniospores from plant to plant. 
Rain accompanied by high wind is known to carry spores of some 

plant diseases (38, 44). It is entirely possible for this to occur with 
any spore capable of wind distribution, as in the present case. 

In 1917 Gravatt and Marshall (45) made studies in the experi- 
mental greenhouse at Washington, D.C. They found that weevils, 
snails, slugs, and sow bugs fed on the uredinia and telia of Cronartvum 
ribicola on the diseased plants. The ingested urediniospores lost 
their viability to a large extent, but not entirely. 

In the same year Gravatt and Posey (46), working at Kittery 
Point, Me., found that gipsy-moth larvee feed quite freely upon leaves 
of Ribes hirtellum and R. vulgare and that in some cases the only 
infected leaves were those which had been partially eaten by insects, 
indicating that they carried the spores which infected the leaves. 
The insects were found carrying viable urediniospores on their bodies. 
There can be no doubt that these insects play an important réle in 
the local distribution of this fungus within the gipsy-moth infested 
area. 

Studies by Snell (127) at Lewis, N. Y., in 1918, show that a large 
number of insects visit Ribes plants during the season when the rust 
is present upon the leaves. The spore-laden insects were inclosed 
in chambers with the tips of Rebes glandulosum plants, and infection 


36 Pennington, L.H. Op. cit. 


58 BULLETIN 957, U. S. DEPARTMENT OF AGRICULTURE. 


resulted in due time. Many of these insects are, of course, accidental 
visitors, but quite a number feed or breed upon the Ribes plants. 
All of those which frequent the Ribes bushes by preference may carry 
many spores of both uredinia and telia. Such insects would be 
most likely to spread the disease, since upon leaving one Ribes plant 
they would seek another, thus scattering the spores exactly where 
they could start new colonies of the disease. But, the accidental 
visitors, in a locality where Ribes bushes are abundant, could also 
spread the spores locally, but in a much more indiscriminate manner, 
so that but a very small percentage of the spores would ever reach 
leaves of Ribes. 

Aside from carrying spores on their bodies, some insects feed 
directly on the uredinia and telia and a few of the excreted spores 
are known to retain their viability. ‘Still other insects may be leaf 
eaters and ingest the rust spores only accidentally. These would be 
of minor importance in spreading the disease. 

At Lewis, N. Y., where the Ribes bushes overhang narrow cattle 
paths which wind through a heavy cover of blackberry, raspberry, 
and other low shrubs, observations by Pennington and Snell indicate 
that cattle, sheep, horses, dogs, and berry pickers may carry the ure- 
diniospores from an infected bush to neighboring healthy ones. 

The remarks on the carrying of zeciospores by automobiles, steam 
trains, and electric cars on page 36 apply also to some extent to the 
‘urediniospores. 

GERMINATION OF THE UREDINIOSPORES. 


The urediniospores of Cronartiwm ribicola have been generally 
found to be erratic in germinating. At one time excellent germina- 
tion occurs; at another, none at all. In the greenhouse experiments 
it seems that urediniospores produced in newly formed uredinia have 
greater infective power than those produced later in the same ure- 
dinia. Such early urediniospores seem to give as good results as 
fresh eciospores. The former are usually produced in limited quan- 
tities while the latter are usually abundant. This results in a more 
liberal use of the latter, so that a fair comparison of the two is not 
possible from the usual inoculation work. Gravatt made compara- 
tive tests and concluded that sciospores and urediniospores from 
newly open sori were about equal in.infective power. More such 
tests should be made before any conclusive statement is made on 
this point. 

Gravatt and York found that newly matured urediniospores pro- 
duced out of doors were decidedly more viable than older ones. 
This agrees with general experience in making inoculations in the 
greenhouse. 

Gravatt found that cooling the urediniospores on ice stimulated 
germination. Uncooled spores gave 15 to 23 per cent germination 


WHITE-PINE BLISTER RUST. 59 


while ice-cooled ones of the same lot gave 25 to 54 per cent germina- 
tion. Marshall found the same stimulating effect from a tempera- 
ture of 23° F. upon urediniospores on Ribes leaves stored outside a 
window, as compared with those on leaves kept at room temperature. 

Posey dried infected leaves of Ribes nigrum in the hot July sun for 
four hours. Urediniospores from these gave germination ranging 
from 3 to 45 per cent, with an average of 17 per cent. Spores from 
other leaves collected at the same time and dried inside in the shade 
gave 3 to 90 per cent germination, an average of 47 percent. During 
dry, hot weather it has been found that the viability of the uredinio- 
spores out of doors is very low. 

Duff (30), in studying the factors affecting their viability, found 
that exposure to bright sunlight reduces their germination, the ultra- 
violet rays being the destructive agent. Their viability appears to 
him to below. Three days after collection less than 50 per cent ger- 
minated in distilled water. In about two weeks germination was 
negligible even when stimulated by cooling to 2° to 5° C. 

Pennington *” made germination tests of newly-matured uredinio- 
spores of Cronartiwm ribicola produced naturally in the vicinity of 
Lewis, N. Y., from early June until late in the autumn in hanging 
drops of tap water. During the first two weeks of June (frequent 
rain) the percentage of germination was high. From June 16 to 28 
no tests were made. On June 29 and July 1 (rather dry) only 1 per 
cent germinated. After this time, many tests were made with spores 
from various localities. By July 14 (very hot alternating with some 
rain) less than one-third of 1 per cent germinated, and from July 22 
to 26 (hot and dry) less than one-tenth of 1 per cent. Fresh yellow 
spores kept in an ice box gave no better results. On August 1 (rain 
July 29 and 30) 5 per cent germinated. After this (decidedly more 
rain) from 10 to 40 per cent germinated. The viability of these spores 
seemed to be greatly decreased by hot, dry weather and increased by 
cool rainy spells at the time they were produced. When the number 
of spores produced decreased because of hot, dry weather, their rate 
of germination also decreased and vice versa. 

Doran (28) found that the limiting temperatures for the germina- 
tion of urediniospores are: Minimum 8°, optimum 14°, and maximum 
25°C. He calls attention to the fact that— 

There is apparently a relation between the season when spores occur and their tem- 
peratures for germination. The ezeciospores of Cronartium ribicola occur in the spring 
when the average temperature is lower than in the summer, the season of occurrence 
of the urediniospores of this fungus. The eciospores of this fungus have a minimum 
temperature for germination, which is 3° C. lower than that of the urediniospores; an 


optimum 2° C. lower than that of the urediniospores; and a maximum 6° C. lower 
than that of the urediniospores. 


37 Pennington, L.H. Op. cit. 


60 BULLETIN 957, U. S. DEPARTMENT OF AGRICULTURE. 


Germination of fresh urediniospores usually takes place readily in 
tap water. Gravatt found that distilled water gave poorer germina- 
tion than tap water. Colley (20) found that the germ tube pushes 
through the exospore without the aid of a germ pore. The contents 
of the spore soon pass into the young germ tube, which may extend 
some distance over the surface of a Ribes leaf. Entry to the interior 
of the leaf appears to be through the stomata. The urediniospores 
germinate in about five and one-half hours (28) in drops of distilled 
water on glass slides. 

During germination studies in 1918, York * occasionally found 
germinating urediniospores which formed secondary conidia. An in- 
vestigation of the conditions causing their formation showed that 
newly formed urediniospores usually do not produce the secondary 
conidia in tap water, while old urediniospores were more likely to 
produce them. ‘The following species produced them, the frequency 
increasing in the order named: frbes lacustre, R. cynosbati, R. vulgare, 
R. reclinatum, and R. nigrum. . Urediniospores from R. glandulosum 
did not produce secondary conidia. Urediniospores exposed in bags 
of mosquito netting out of doors gave especially abundant secondary 
conidia. Urediniospores from &. nigrum produced secondary conidia 
in weak solutions of ammonia, maltose, tannic acid, gallic acid, malt 
extract plus gallic acid, lactose plus: tannic acid, and lactose plus 
gallic acid. They were especially abundant in the last solution. 
They were not produced in pine decoction, weak solutions of ether, 
lactose, maltose plus tannic acid, and maltose plus gallic acid. A 
limited number were produced in water. They form on the ends of 
the germ tubes or laterally and are capable of producing a germ tube 
themselves. Similar secondary conidia have been noted by Tulasne — 
(175) in cultures of Cronartiwm asclepiadeum, and they have been 
noted by Plowright (109) and Sappin-Trouffy (122) in other Uredi- 


nales. 
LONGEVITY OF THE UREDINIOSPORES. 


The first experiments in testing the longevity of urediniospores of 
Cronartium ribicola seem to have been -carried out by McCubbin * in 
1916. His manuscript account of these experiments follows: 


The spores used for this series were all collected on the same day. They were dried 
on paper for a few hours and then placed in a number of small bottles plugged lightly 
with cotton, the contents of each bottle being available for a single inoculation. 
Half of these bottles were kept on a shelf in the laboratory, where they were dry and 
exposed to weak light, and the other half were placed under a bell jar on the soil 
in a garden, exposed to changes of humidity, temperature, and light. 

At stated intervals a bottle was taken from each set and the spores within were 
shaken up with a small amount of distilled water. By the use of a small atomizer 
the suspension of spores was then sprayed on the under side of the leaves of small 


= Se 


38 York, H. H. Op. cit. 
39 McCubbin has very kindly allowed the use of his unpublished data so as to make this account as com- 
plete as possible. 


WHITE-PINE BLISTER RUST. | 61 


currant plants which had been previously set out in an isolated garden for the pur- 
pose. After inoculation the plants were covered for two days by a box having a glass 
lid. In all cases, water was sprinkled three or four times daily on the plants and 
on the inside of thé box, to keep a high humidity. Unfortunately, during the whole 
of the period covered by this series of inoculation the weather was exceedingly hot 
and dry, and it was evident from a study of field conditions that infections could take 
place at this time only with the greatest difficulty. The adverse nature of the weather 
conditions will serve to explain the meager results. 

The only positive result from this experiment was that the spores would retain 
their power of infection for a period of nine days at least; but so many failures oc- 
curred all through the course of the work that this period can not be regarded as 
establishing a maximum limit of life. 

It is interesting to note that the spores kept outside underwent a complete decolori- 
zation in two days, whereas those stored in the laboratory retained their normal 
color, with but little change throughout the whole time of the experiment. 

The inconclusive results obtained from the first set of inoculations in the field led 
to another later attempt with plants kept in the laboratory, for this purpose a number 
of small plants being used from which the leaves had been stripped, so as to induce 
the formation of secondary foliage. The methods employed in this case were the 

same as for the first set, exept that after inoculation the shoots were kept covered 
and moistened for the usual 48 hours inside large glass jars. (See Table IV.) 


TaBLE IV.—Jnoculation of currants with uredospores of different ages. 


Age of : fe Number ; 
Series. spores Date Bae hea of leaves ake = Pe sa Result. 
(days) y used. o é 
EERE Ses. ..!. De Aro Stt3 1 I 16 | September 19_.:...| 5 pustules on 2 leaves. 
es Saat aed. £2 4 | September 2....... 16 | September 22......| 67 pustules on 11 leaves. 
UU Desa 8 8 ee 7 | September 5....... 16 | September 25......| Noinfection. 
IE Se 82 3.2 sh 8 | September 6...--.-. 14 | September 26......| 10 pustules on 5 leaves. 
Wren. 232%... 21» 11 | September'9--.: .. 11 | September 29...... 8 pustules on 2 leaves. 
Wa tek. 13 | September 11.-.... HOM POCvOMer Me senso 2 pustules on 2 leaves. 
Mime ee: fe 18 | September 16-.--.-- 5 | October 6..-.....-- No infection. 
VIN U0 00 RES ts Bae 24 | September 22...... 4M, | OCvoueIvt 2: aaen qe Do. 
ERG 5 SE Lis 27 September: 25: .2..: Mi eOetober 15PeIh a. ¥ Do. 
p:<3 OU 8 eee 31 | September 29...... ap Ootover lore. .- Do. 


The results from these inoculations were somewhat better than those from the first’ 
set; infectioris were obtained from spores kept for 13 days after collection, as shown 
in the tabulated record. It is still thought that this period is far below the maximum 
period for which the spores will retain their vitality. 


In 1917 Gravatt and Taylor made a series of tests of urediniospores 
together with sciospores and teliospores. _ (See p. 38 for details 
of the experiment.) They were tested weekly beginning May 8. 
June 16 gave the last germination in lot A, while lot B persisted 
until July 2. Although germination persisted longer in lot B, it 
weakened decidedly somewhat earlier and was poorer practically 
throughout the test. (See Table II, p. 38.) 

In 1918, Duff (30) experimented on the longevity of urediniospores 
placed in a refrigerator at 2° to 5° C. two weeks after collection and 
tested in hanging drops of distilled water. He states that when 
placed in the refrigerator— 


A negligible percentage of spores were germinable, but reduction in temperature 
stimulated them to greatly increased germination. By this means a continually 


62 BULLETIN 957, U. S. DEPARTMENT OF AGRICULTURE. 


decreasing percentage of spores were kept in a viable condition, until after a lapse of 
a further period of about three weeks the number that germinated readily was negli- 
gible once more. Before the end of four weeks the spores had ceased to germinate. 

Extensive tests of the longevity of urediniospores were made by 
York, Overholts, and Taylor. In one experiment leaves of Ribes 
ngrum, R. vulgare, and R. reclinatum were placed in bags of mosquito 
netting with the uredinjospores outward. The bags were placed:on 
three stakes at 6-inch intervals, the lowest one touching the ground 
and the highest 5 feet above the soil. The lowest spores remained 
viable only 6 to 9 days, while the upper ones were viable longest, 65 
days. A 2-day rain began the day after starting the experiment and 
again a 1-day rain two days later. The urediniospores from R. 
nigrum remained viable longest. Again infected leaves of Ribes 
nigrum, R. vulgare, R. cynosbatr, and Rf. glandulosum were put in open 
boxes and exposed for 4 hours to the early morning sun. Viability 
persisted only 15 days. The urediniospores from Ribes nigrum re- 
mained viable longest. Urediniospores on pulled bushes of Ribes 
glandulosum and R. cynosbati hung in the bright sun remained viable 
only 4 days. Spores on leaves of Ribes nigrum dried in a plant press, 
then put in tight Mason jars and stored in an ice-box remained viable 
80 days. Successful inoculations were made with urediniospores col- 
lected 270 days previously and also with urediniospores from dead, 
overwintered leaves of the previous season. The age of the spores is 
not known, but they were certainly overwintered spores (180). It 
was found that viability in tap water persisted at least 169 days 
when the spore-bearing leaves were air dried and kept under slight 
pressure between sheets of heavy glazed paper. When kept out of 
doors but protected from rain, they retained viability for 100 days. 

In 1918 Pennington‘! made a number of tests of the longevity of 
urediniospores. In July and August urediniospores on Ribes leaves 
brought into the laboratory and air dried lost their viability within 
a week when tested in drop cultures of tap water. On September 25 
many Ribes leaves were collected and allowed to dry between sheets 
of paper. The second day urediniospores from these leaves gave 
50 per cent germination when tested as above. The leaves were 
left in the dry air of the laboratory. The spores decreased in viabil- 
ity until November 26 when but 1 per cent germinated. After that 
there was no germination. 

These results, showing a longevity ranging from 7 to 270 dag 
under varying bonding indicate the sensitiveness of the uredinio- 
spores to external factors. In addition it is quite possible that the 
physiological condition of the host plant also has a profound effect 
upon these spores. 


40 York, H. H., Overholts, L.O.,and Taylor, M.W. 'Thelongevity ofthe sporidia of Cornartium ribicola. 
Seen in manuscript. To be published in Phytopathology. 
41 Pennington, L. H. Op. cit. 


WHITE-PINE BLISTER RUST. 63 


THE TELIA AND TELIOSPORES. 


GENERATIONS OF TELIA. 


In 1918 Pennington “” made observations upon the generations of 
telia at Lewis, N. Y. This was a season very favorable for the 
occurrence of distinct waves of spore production. The first genera- 
tion of telia appeared on June 28 with and following the second 
crop of uredinia. ‘They were present throughout the rest of the 
season, but in the greatest abundance with and immediately follow- 
ing a new generation of uredinia. As compared with the uredinia, 
they were produced in relatively greater abundance with each 
succeeding generation. There were six distinct waves of telial 
production. 
SEASON OF PRODUCTION OF THE TELIA. 

The date when the first telia are produced varies from year to 
year with the earliness of the season. The earliest of which we have 
definite record is June 2, 1918, at North Conway, N. H. Table V 
(p. 72) gives data for the different regions of North America. 
The telia are formed until the Ribes leaves fall in the autumn. 
Drought is likely to cause premature shedding of diseased Ribes 
leaves soon after the first teliaform. This greatly limits the produc- 
- tion of new telia. 
( DISTRIBUTION OF THE TELIOSPORES. 


Because the teliospores are produced in more or less compact 
columelle they are normally not separated from the host plant. 
They do become distributed somewhat, however. Gravatt and 
Marshall (45) found that slugs eat telial columns from rusted Ribes 
leaves; also that sow bugs carry broken columns on their bodies. 
There seems to be no reason why insects and other animals may not 
do likewise. 

The telia are sometimes mechanically broken off and blown about 
by the wind. 

Diseased Ribes leaves fall to the ground and are blown about by 
the wind. Often they are broken into small pieces which may be 
blown long distances. In fact, York # found such bits of dead 
leaves in his spore traps 200 feet distant from the nearest Ribes 
bush. Telia on dead leaves kept out of doors in the shade are 
known to retain viability for 65 days, so that in this way the disease 
might appear in very unexpected places on pines at a greater dis- 
tance than the sporidia are carried in a viable condition. 


GERMINATION OF THE TELIOSPORES. 


The teliospores germinate readily in tap water and odes sporidia 
in 6 to 12 hours.“ Each spore produces normally a 4-celled pro- 


42 Pennington, L. H. Op. cit. 
48 York, H.H. Op. cit. 
“ York, H. H., Overholts, L. O., and Taylor, M. W. Op. cit. 


64 BULLETIN 957, U. S. DEPARTMENT OF AGRICULTURE. 


mycelium. Lach cell regularly puts forth a stout sterigma on which 
the very thin walled, globular sporidium soon develops. The 
sporidium has a tiny papillalike swelling where it was attached to the. 
sterigma. The sporidia are 8 to 10 microns in diameter (20). The 
germ tubes of the teliospores, if developed under water, may not 
form promycelia but extend elongated hyphse (20). Under favorable 
conditions a high percentage of the teliospores may germinate, but 
because of their aggregation into columelle it is impossible to make 
an exact count of the germinating spores. Cooling on ice stimulates 
viability markedly. 


LONGEVITY OF THE TELIOSPORES. 


The longevity of the teliospores of Oronartium ribicola does not 
seem to have received as much attention as that of the eciospores 
and urediniospores. Gravatt and Taylor made tests with telio- 
spores in 1917 similar to those described as made by them with 
eeclospores and urediniospores. (See Table II.) Weekly tests 
showed that germination persisted in lot B 35 days, while it lasted 
56 days in lot A. Saprophytic fungi attacked the lot kept on the 
window sill, so that the test probably does not show the longevity 
of healthy teliospores. 

York * in 1918 found that teliospores were still capable of germi- 
nation in tap water after being kept on the plucked leaves 65 days 
out of doors in the shade. A similar test of teliospores kept in the 
dark in the laboratory gave germination for 90 days. 


THE SPORIDIA. 


SEASON OF PRODUCTION OF THE SPORIDIA. 


The sporidia may be produced as soon as the telium is mature, if 
there is sufficient moisture in the air for a number of hours. | 
The telia may remain alive on dry dead leaves out of doors for 
more than 65 days, so that sporidia might be produced well into the 
winter in mild seasons, thus prolonging the danger season for pines. 


DISTANCE OF DISSEMINATION OF THE SPORIDIA. 


In work with spore traps by Pennington “ and Snell in 1918, 
sporidia were caught up to 60 feet from very heavily infected Ribes 
bushes. This was in the eastern Adirondacks, about 8 miles from 
Lake Champlain. Hundreds of pines were examined for infections. 
In no case was infection found on pines as far as 200 feet from Ribes 
plants. Pennington made a study of nine outbreaks in pines in the 
Adirondacks. The infection on pines was confined to an area 
within 100 to 200 feet of the Ribes plants which infected the pines. 


45 York, H. H. Op. cit. 
46 Pennington, L. H. Op. cit. 


a 


WHITE-PINE BLISTER RUST. 65 


In 1919, Pennington (cited in Spaulding, 146) caught sporidia up 
to 294 feet distant, but they failed to germinate. Under favorable 
conditions, sporidia caught at a distance of 177 feet germinated, 
but none beyond this distance. 

York,” working in the White Mountain region of New Hampshire, 
in 1918, found that sporidia were quite common in spore traps 
exposed 24 hours at a distance of 200 feet from the diseased Ribes 
bush. York (cited in Spaulding, 146) in 1919 caught sporidia, under 
favorable conditions, at 600 feet distance, which germinated. 

The infection of pines is said by McCubbin (88) to depend on 
“(1) The nearness of cultivated Ribes, particularly black currants; 
(2) the number of wild Ribes present; (3) the moistness of the situ- 
ation.”” York‘ concluded that these factors are ‘‘ topographical 
features, direction of the wind when sporidia are produced, humidity 
of ‘the air, precipitation, and the nature and density of vetegation 
between the Ribes and pines.’”’ Pennington “ stated that weather 
conditions have much to do with the degree of infection that occurs 
on pines; cool, moist situations favor infection; intervening barriers 
of vegetation tend to limit infection; the amount of infection under 
given conditions varies directly as the extent of Ribes leaf surface 
and inversely as the square of the distance from Ribes. The writer 
(145) said the width of the Ribes-free zone around pines is largely to 
be governed by topographical features; direction of the wind pre- 
vailing at the time the sporidia are produced; humidity; age of the 
pines; exposure and species of Ribes; and the composition, height, 
and density of the vegetation between the Ribes plants and the pines. 
The experiments with the sporidia show that high humidity is neces- 
sary for these spores to live any length of time. It alone may very 
largely determine whether infection can take place. _ 

A few specific instances show the effect of these factors in actual 
outbreaks. On July 10, 1917, on Gerrish Island, at Kittery Point, 
Me., Gravatt investigated the small trees of Pinus strobus within a 
radius of 15 feet of a bush of Ribes hirtellum to determine the spread 
of infection. The gooseberry was a small bush, having approximately 
270 small leaves and there were no other Ribes near by to influence 
the result on pines. The ages of the pines were as follows: Two 
years, 12; 3 years, 17; and 5 years, 82; a total of 128 pines, none | 
over 5 years of age. There were 77 separate infections on 54 dis- 
eased trees, 44 of these infections being on, 2-year wood. As the 
oldest pines were 5 years old and most of the infections which occurred 
the year before were probably not detected, this infection of more 
than 40 per cent resulted from an exposure of only a little more than 


werork, U1. H. Op. cit. 
48 Pennington, L.H. Op. cit. 


46103°—21—Bull. 957-5 


66 BULLETIN 957, U. S. DEPARTMENT OF AGRICULTURE. 


3 years to the disease. To judge from the results of the first five 
years, it is not likely that any of the pines within the 15-foot radius 


would remain alive at the end of 12 or 15 years. Pines outside the 


15-foot radius from the bush showed only scattering infections. 
This was in a location well protected from strong winds. 

In another case where Ribes nigrum was well exposed to the strong 
storm wind from the neighboring White Mountains, York found 
pine infections up to 600 yeards distant from heavily diseased Ribes 
bushes.* 

In the outbreak at Kittery Point, Me., Posey found that a num- 
ber of Ribes nigrum bushes so located that the wind had moderate 
access to them caused infection of Pinus strobus trees up to a distance 
of about 300 yards. 

Our studies (146) of the distance of distribution of the various spore forms and of 
the distance that infection has actually occurred upon pines from known infected 
Ribes indicate that the Ribes-free zone should be, under average conditions, 200 to 
300 yards in width. It should be much more where conditions are exceptionally 
favorable for transfer of the spores from Ribes to pine, i. e., near large bodies of Ribes, 
where there is no screen of vegetation over the Ribes or between the Ribes and the 
pines, or in exceptionally humid situations. The cultivated black currant (Ribes 
nigrum) should not be allowed in an infected pine district because of the special 
danger from it. 

Studies by York * of the natural infections of pines show that the 
sporidia are blown along roads cut through heavy forest cover and 
that they do not reach pines located in isolated small pockets in the 
dense forest. ‘Trapping of sporidia from Ribes located under dense 
cover of black alder yielded sporidia only up to a distance of 75 feet. 
Traps set 20 feet in the air and well above the cover, but directly 
over the Ribes bushes, caught no sporidia. 


AGENTS DISSEMINATING THE SPORIDIA. 


It is apparent that the sporidia produced by the teliospores of 
Cronartium ribicola are largely disseminated by the wind. Observa- 
tions in various areas where white pines have become infected from 
neighboring Ribes bushes show plainly that this is the case. In such 
cases the infection is most intense nearest the Ribes bush acting as a 
center of infection. The degree of infection decreases as the distance 
from the center increases. Other conditions being equal, the distance 
of pine infections from the infection center is very short where there 
is a thick screen over and around that center, while the converse is 
true where the Ribes infection center is well out in the open. (See 
pp. 64 to 66 for data bearing on this matter.) 

Minor disseminating agents are known, and their number will 
undoubtedly be increased by future investigations. The investi- 
gations of Gravatt and Marshall (45) in the experimental greenhouse 


49 York, H. H. Op. cit. 


‘ 


WHITE-PINE BLISTER RUST. 67 


at Washington, D. C., showed that weevils, snails, slugs, and sow 
bugs feed on the telia. The voided teliospores retained viability in 
. afew instances. This indicated that similar animals might be active 
agents in the local distribution of these spores out of doors. Investi- 
gations by Snell (127) in 1918 at Lewis, N. Y., showed that a number 
of different types of insects feed on rusted leaves of Ribes bushes and 
may serve as carriers of the sporidia directly from plant to plant, or 
indirectly by the voided teliospores. - Marshall, in 1917, found that 
the moist sporidia allowed to dry on a feather are not easily dis- 
lodged therefrom, either by wind or by brushing of the feather on 
cloth. This suggests the possible carriage of sporidia by migrating 
birds in the fall for long distances. Their very short life, as deter- 
mined by York (see pp. 67--68), however, probably prevents their 
causing infection of pines under these conditions. 

The remarks on the carriage of eciospores by currents of air gen- 
erated by fast-moving automobiles, steam trains, and electric cars also 
apply to the sporidia. (See p. 36.) 


GERMINATION OF THE SPORIDIA. 


Gravatt, Colley (20), and York, Overholts, and Taylor *® found 
that the sporidia germinate immediately in tap water under favor- 
able conditions. They germinate like ordinary fungus conidia, by 
pushing forth a germ tube which is relatively large. They are capable 
of germination as soon as they reach full size, even though still 
attached to the promycelium. ~The germ tube normally develops 
until a mycelium is formed. In some cases the germ tube soon forms 
a secondary sporidium which in turn may germinate. The viability 
of the fresh sporidia is high, as wae as 90 per cent germinating 
within 24 hours. 


LONGEVITY OF THE SPORIDIA. 


The sporidia of Cronartwwm ribicola are so thin walled and fragile 
in character that it seems self-evident that they are short-lived spores. 
This supposition has been proved to be correct by the work of York 
and Overholts in the summer and autumn of 1918 and of York and 
Taylor in 1919 (cited in Spaulding, 146). Colley (20) found in 1917 
that fresh sporidia germinated readily in distilled-water cultures. - 
York, Overholts, and Taylor © dried the sporidia on glass slides and 
tested their viability after varying intervals. Very slight germina- 
tion resulted after 10 minutes exposure by an open window at 66° F. 
when light rain was falling. None survived when exposed to bright 
sunlight for 10 minutes with a temperature of 77° F. Nor did they 
_ survive when pieces of Ribes leaves bearing the telia and sporidia 
were exposed to sunlight for 10 minutes at 85° F. and with a humidity 


0 York, H. H., Overholts, L. O., and Taylor, M, W. Op. cit, 


68 BULLETIN 957, U. S. DEPARTMENT OF AGRICULTURE. 


of 30.5 per cent. In another experiment the sporidia were placed 
on the periderm of white-pine twigs of the same season’s growth and 
on living leaves of Pinus strobus and P. rigida. They were then 
exposed dry at 66° F. and with a humidity of 90 per cent. None 
survived for 10 minutes. At 72° F. and a humidity of 69 per cent 
none survived for 10 minutes. They conclude that the sporidia can 
endure very little desiccation and are short lived under seemingly 
optimum conditions. Abundant moisture is necessary for infection 
of pines to occur. | 


HETER@CISM OF THE SPORIDIA. 


A number of tests have been made to learn whether Ribes might 
become infected by sporidia of Cronartvum ribicola. Jaczewski (59) 
states that experiments have shown that they will not infect Ribes 
leaves. In 1913, Clinton, Stewart, and the writer (151) inoculated 
Ribes nigrum leaves with teliospores overwintered out of doors, but 
there were no infections. In 1912 the writer tested fresh teliospores 
without infection occurring (136). In 1917 Gravatt made several 
tests of fresh, sporidia-producing telia, but no infection resulted. — 


OVERWINTERING OF CRONARTIUM RIBICOLA. 


Overwintering on Pines. 


The generally accepted view has been that Cronartium rabicola 
lives over winter by means of the mycelium in the bark of living 
infected pines and by this means only (142). A number of writers 
have mentioned cases where their observations seemed to indicate 
the possible overwintering on infected Ribes, but nothing that could 
be accepted as real evidence was offered until the last few years. 
There is no question that the fungus overwinters chiefly in the 
infected living pine trees and has been carried in the dormant con- 
dition from continent to continent in young infected pines. 

It has been discovered,:as has been mentioned earlier, that Cro- 
nartium ribicola may overwinter as mycelium in infected branches 
cut from diseased trees late in the fall, or during the winter, and 
allowed to lie until spring. Then, if these cut-off branches lie close 
to damp soil or with the cut ends in a stream or pool, fresh vigorous 
' gcia are produced (89). Still another phase of overwintering was 
discovered by Dosdall (29) in Minnesota. On April 19, 1918, a 
dead branch of white pine, bearing an infection which bore ecia in 
1917, was collected. Germination tests in distilled water showed 
that 1 to 2 per cent of the old zciospores were still viable. 


Overwintering on Ribes Plants. 


Investigations of overwintering of Cronartwum ribicola on Ribes 


plants, in Europe, seem to be limited to field observations. They P 


Se 


WHITE-PINE BLISTER RUST. 69 


relate to instances where diseased Ribes bushes were found widely 
separated from Pinus strobus or from all 5-leaved pines (6). These 
necessarily depend for reliability upon the observer’s complete and 
minute knowledge of the Ribes and pines within considerable areas. 
Hence, such observations are of very uncertain value. Investiga- 
tions showing that the xciospores of this fungus are distributed for 
miles largely invalidate such observations so far as overwintering is 
concerned. 

In North America, investigations of overwintering on Ribes plants 
have been along the following lines: (1) By means of spores adhering 
to dormant Ribes plants, (2) in dormant or partially opened Ribes 
buds, (3) in living Ribes leaves which themselves lived over winter, 
(4) on dead Ribes leaves, and (5) on infected Ribes stems. 

Overwintering by means of spores adhering to dormant Ribes 
plants has been investigated in several ways. A great many field 
observations have been made upon bushes diseased heavily one year 
and not infected the succeeding year. Cases where bushes were 
shipped from known diseased localities and have shown the rust the 
next season in their new locations, have been considered, but the 
evidence has been too incomplete to be seriously considered except 
as it might help to confirm or refute other stronger evidence. A 
great many Ribes plants have been used by the writer in greenhouse 
experiments; they shed their leaves and become dormant for several 
months, yet there has been no hint of the carrying over of the fungus 
upon them from one season to the next. A cooperative experiment 
was made with Stewart (151), using 500 plants of Ribes nigrum, which 
in the summer of 1912 were heavily infected. The leaves dropped 
normally. They were then dug and most of them heeled in out of 
doors until February, 1913. They were then brought into green- 
houses in six widely separated localities and allowed to put forth 
new leaves. Examination of some of these dormant plants by Arthur 
and Petry showed that plenty of urediniospores still adhered to the 
stems and buds. Inoculations with these spores did not give any 
infection, so that they presumably had lost their viability. The 
results reported by six different investigators showed no infection 
appearing on the new leaves. 

Howitt and McCubbin (56) in attempting to solve the overwinter- 
ing problem, made the following tests: 

(1) In the fall of 1914, 16 black and 7 red currant bushes and 1 gooseberry bush,, 
all badly rusted, were stripped of leaves and placed in cold storage, where they 
remained until March 16, 1915. At this date they were removed and planted in a 
greenhouse. All grew well and produced healthy leaves and fruit and were entirely 
free from rust throughout thesummer. In addition, 17 black currant bushes, which 


had been badly rusted in 1914 and which were wintered in the field, were added to 
the above on April 21, 1915. These also grew normally and without rust. 


70 BULLETIN 957, U. S. DEPARTMENT OF AGRICULTURE. 


(2) Seventy-eight black currant bushes, badly rusted in 1914 were wintered in 
the nursery rows, and transplanted April 12, in various gardens, isolated as far as 
possible from infected white pines and currants. These were inspected six times 
during the summer, the last inspection being made on October 2. At this date all 
were still free from rust except two bushes, on each of which a few rusted leaves 
were found. There is reason, however, to suspect that these infections might have 
been due to spores carried from currants about a mile distant from the garden in 
which they occurred. In no case was rust found on any of these currants which 
were located more than a mile from a source of infection. 

(3) A number of bushes from the same source as No. 2 were planted in five lots in 
a region known from personal observation to have been entirely free from the rust in 
1914, and which is 60 miles from the nearest known source of infection. Of the 100 
bushes set out here only one developed rust, and this late in the season. All con- 
ceivable sources for this infection have been accounted for except two, viz, the 
wintering over of the rust on the currant itself, or accidental infection from spores 
carried on the writer’s clothing while making an inspection on May 24. 


In 1917, V. B. Stewart (152) tested the possible overwintering of 
the fungus by means of spores adhering to diseased bushes of Ribes 
nigrum. These were heavily infected in 1915 and 1916. In August, 
1916, they were defoliated, and 200 were dug and placed in a storage 
cellar in October, where they remained all winter. In 1917, they 
were sent to Ithaca, N. Y., and set out in a field. The disease had 
not been known within 40 miles. The disease did not appear upon 
them up to October 9, 1917. ; 

The possibility of overwintering in Ribes buds was brought to the 
writer’s attention by infections of petioles (131, 134, 1385), by which 
means it seemed entirely possible for the mycelium to travel from a 
leaf blade down the petiole and thence into the stem and bud in the ~ 
axil of the leaf. While many diseased petioles have been examined, 
no indication of the migration of the hyphe into the stem or bud has 
yet been seen. Direct examination of buds on heavily infected 
bushes has also failed to yield any indication of bud-scale infection 
(151). McCubbin (85) suggested but could not prove that infection 
of partially opened buds late in the fall might result. some of the 
infected leaflets surviving the winter and developing the disease the 
next spring. York*! successfully inoculated the inner bud scales of | 
opening buds of Rabes negrum with eciospores, suggesting overwinter- 
ing in this way. 

The possibility of green leaves living over winter on Ribes plants 
out of dcrrs has been investigated. In three cases, the writer had 
Ribes plants growing in pots plunged in sand out of doors at Wash- 
ington, D. C., retain green leaves through the winter until the spring 
weather of March, 1918, set in. One plant of Cumberland goose- 
berry and two plants of Utah Yellow currants did this. ‘They were 
taken as specimens on March 22, when warmer weather set in. The 


5. York, H. H. Op. cit. 


WHITE-PINE BLISTER RUST. 71 


previous winter a single seedling plant of an unknown species bore 
leaves flat on the soil under similar conditions until March 12, 1917, 
when it was brought into the greenhouse and inoculated. It 
promptly took the disease on the overwintered leaves. York” found 
Ribes glandulosum plants in the spring of 1918 which bore overwin- 
tered leaves that later became infected naturally. In such cases, it 

* would be easy to understand that late infections in the fall might lie 
dormant until spring and then produce vigorous uredinia. More 
time is necessary to determine whether this actually occurs. 

As stated previously, infection of petioles by Cronartiwm ribicola 
is quitecommon. Early in 1917 Colley (17) discovered that infected 
petioles often had telia and masses of active mycelium as well as 
uredinia in the central pith. This raised the question of the possi- 
bility of such mycelium remaining active until spring and producing 
new uredinia. 

Whether the fungus can live over winter on dead diseased leaves 
seemed unlikely in view of the negative results of Arthur and Petry 
(151) with urediniospores from stems of plants diseased the preceding 
summer, and the negative results of Stewart (151) with material 
overwintered out of doors at Geneva, N. Y. Howitt and McCubbin 
(56) early in 1915 attempted to produce infection by spores which 
remained over winter out of doors on dead Ribes leaves. All of their 
attempts were unsuccessful. In the spring of 1918 York (180) and 
the writer obtained infections with urediniospores overwintered out 
of doors in Massachusetts on dead Ribes leaves, proving that uredi- 
niospores may survive the winter. This was repeated in the spring 
of 1919 by Taylor (157). 

The possibility of infection on Ribes stems was early investigated 
by the writer but with no success. Many inoculations were made on 
young Ribes shoots by the writer and later by Gravatt, Doran (28), 
and York * but without success. However, in the summer of 1917, 
Posey and Gravatt (112) discovered fruiting uredinia on the young 
shoots of Ribes hartellum at Kittery Point, Me. They inoculated 
other young shoots with sciospores and secured mature uredinia. 
Colley found uredinia in the pith of these infected stems. Gravatt 
later inoculated young seedlings of Ribes fasciculatum in the green- 
house with eciospores and secured heavy infection of the cotyledons. 
In one seedling the fungus also attacked the stem just below the 
diseased cotyledons and developed several uredinia (Pl. V, fig. 2). 
Later, however, the plant outgrew the disease. Taylor and York 
have successfully inoculated stems of several species of Ribes. (See 
p- 50.) 

That Cronartiwm ribicola overwinters on Ribes is established. 


82 York, H. H. Op. cit. 


2 


IMPORTANT DATES IN THE LIFE HISTORY OF CRONARTIUM RIBICOLA. 


BULLETIN 957, U. S. DEPARTMENT OF AGRICULTURE. 


Table V shows some of the more important dates in the develop- 
ment of the white-pine blister rust and their variation according to 
locality. These dates are rarely the earliest or latest possible ones, 
but are based upon notes actually made respecting the point covered. 
It is hoped to extend this table greatly and approach nearer the 
actual date when each stage of development is reached by the fungus 
in the various regions. Southern New England is here made to 
include Massachusetts, Connecticut, and Rhode Island. Northern 
New York is understood to include approximately that part of the 
State lying north of a line between Glens Falls and Oswego. The 
Lake States include Michigan, Wisconsin, and Minnesota. Similar 
data for Europe are given in the last columns of the table for the 
sake of comparison. . 


TaBLE V.—Important dates in the life history of Cronartium ribicola, as observed in 
America and in Europe.@ 


{To economize space, the century digits 19 are omitted in noting the year of each observation; thus 


Development 
noted. 


First closed blis- 


First uredinia .. . 


First telia< 2 ocu 


First pycnial 


09= 1909.] 


United States. 


Europe. 


Southern 
New 
England. 


ASE Pig | 
. 5,718 


Pi Ag! 
Mar. 28,719 


June 3,716 
June 13,717 
May 29,718 


June 7,718 


Southern 
New York, 
New Jersey, 
and eastern 

Pennsyl- 

vania. 


Apr. 30,711 


June 1,709 
July 27,710 
May 5,711 
June 10,713 
May 20,715 
Apr. 7,716 
Apr. 28,717 
May 16,718 


June 10,713 
July 18,716 


a Notations for Ontario, Canada: First open blisters— May 10, 1917, and June 22, 1918; first uredinia— 
June 24, 1915, and July 20, 1916; first telia—June 24, 1915. 


b Abbreviations used: B= Berlin, Bo=Bohemia, D= 


nich, S= Silesia. 


Northern 
New 
England. 


Northern 
New York. 


Apr. 15,710 
ADD axle LZ 
May 13,718 


June 14,’09 
May 26,710 
June. 9,711 
May 15,712 


June 7,710 
July 1,717 
July 21,718 


ee Oe 


June 26,713 
July 24,716 
June 10,717 
June 2,718 
June 6,719 


July 26,713 
June 7,718 


Apr. 26,718 
Apr. 21,719 


See ee 


June 8,’09 
May 12,710 


Apr. 26,18 | 


Apr. 23,719 


Lake States. Date. 


May 24,716 

May 8,717 \apr. 
Apr. 19,718 | Apr. 29, 796 
Apr. 22,719 | Apr. 28,708 


See ee ee ee es ee 


Se ee es ee 


June 12,718 
June 26,719 


July 25,709 
July 18,716 
June 28,717 
May 16,718 
May 23,719 


Aug. 23,717 
June 26,18 
June 30,719 


June 24,717 | May 15..... 
June 24,719 | May 9...... 
Sept. 16,’19c) June l.....- 
May 19,718 


June . 9,716.| May 23..... 
June 12,717 | May 30..... 
May 18,718 | May 26..... 
June 5,719) June 2,719 


July 21,7161) Agieeke oe 
June 12,717 
July 8,718 
July 10,719 


July 3,718 
June 26,719 


Denmark, F=France, H= Hamburg, M= Mu- 


= to 
< 
tia Py eh | £8 


— 


nwwd ti Poh 


eal foe) 


a 


Pend 


c This date is an extraordinarily late one for «cia to be formed, but it is included here to show the possi- 
bility of the «cial season being prolonged throughout the summer. 


be enti, oe 


WHITE-PINE BLISTER RUST. 78 


CONTROL OF THE WHITE-PINE BLISTER RUST. 
Significant Factors Which Determine Control. 
FACTORS IN THE FUNGUS. 


The significant features in the life history of Cronartiwm ribicola 
are as follows: The pycnospores are apparently functionless; the 


- eciospores are not known to infect pines, but they do infect Ribes 


readily; the urediniospores are not known to infect pines, but they 
do infect Ribes; the sporidia produced by the teliospores are not 
known to infect Ribes, but they do infect pines. 

The spores are all distributed by the wind much more than by any 
other agency. The eciospores are carried and are capable of infect- 
ing Ribes leaves miles away from their source. The urediniospores 
are distributed a number of hundred yards, but appear to lose their 
viability soon, so that infection by them is rather limited in extent. 
The sporidia produced by the teliospores appear to be distributed 
to a distance of a few hundred yards, but they are so frail that they 
soon lose viability. Infection by them is limited to 100 to 600 yards 
as a general thing, and more commonly the former than the latter 
distance. 

The fungus lives over winter most commonly by means of the 
mycelium, presumably in the needles and certainly in the bark of 
infected white pines. It occasionally overwinters by means of the 
geciospores in cankers of pine bark or by the urediniospores on Ribes 
leaves. The eciospores produced by the overwintered mycelium 
in the pine bark are the principal source of infection of the Ribes 
leaves each spring. The eciospores carry the disease far and wide 
for miles to the new Ribes leaves. The urediniospores intensify 
the disease in the vicinity where it is started by the sciospores. 
The sporidia carry the disease back to those pines which are rela- 


_ tively near infected Ribes bushes. 


High humidity of the air is necessary for any of the spore forms to 
germinate and to produce infection. 


FACTORS IN THE ENVIRONMENT. 


CLIMATIC FACTORS. 


Climate may be reduced to the three most potent factors—mois- 
ture, sunshine, and wind. Cronartiwm ribicola is absolutely de- 
pendent upon abundant moisture for its development. Drought, 
especially if prolonged, apparently may hinder the development of 
the ecia (49, 135). Lack of moisture prevents germination of all 
the different forms of spores. It prevents or very greatly reduces 
the extent of infection on Ribes plants by eciospores. It prevents 
the production of new generations of urediniospores, * and conse- 
quently prevents the abundant formation of uredinia as well as 


3 Pennington, L. H. Op. cit. 


74 BULLETIN 957, U. S. DEPARTMENT OF AGRICULTURE. 


restricts the spread of this stage of the fungus. Moreover, drought 
very largely reduces viability of the urediniospores.** With the 
very short-lived sporidia of the teliospores it is evident that lack of 
moisture immediately after their production may entirely prevent 
their infecting pines at all, and drought is known greatly to limit 
their formation. Drought causes the premature fall of leaves of 
_ Ribes bushes so as to leave practically nothing for the fungus to sub- 
sist upon late in the season. Thus the crop of teliospores is so 
greatly reduced in times of drought that infection of pines is largely 
or entirely prevented. Drought kills many young Ribes seedlings 
and many are winterkilled (23, p. 8). On the other hand, rain 
undoubtedly beats down the spores floating in the air and washes 
spores from the host plants, so that infection by them is prevented. 

Sunshine, by influencing the moisture of the air, may be very potent 
in reducing the activities of the fungus. It has a direct deleterious 
effect upon the spores * (80, 88). It is an open question whether the 
erratic germination of the urediniospores is not due to this action of 
the sun’s rays. By promoting the quick maturity and hardening of 
the leaves of Ribes in the open, bright sunlight may greatly reduce 
the infection which develops upon them. 

Wind is apparently the chief agent disseminating all forms of 
spores of this fungus. Its activity greatly influences the spread of 
the disease. | 


THE AGENCY OF MAN. 


Man is a most potent agent in the dissemination of the white-pine 
blister rust. Through his activities it has made all of its known 
long-distance jumps. There is reason to believe that it is a native 
of northern Asia, whence it spread to Europe. The extensive trade 
in young trees of Pinus strobus is known to have been the means of 
introduction of this disease to many parts of Kurope (111, 120, 155, 
162, 170). It certainly came to North America in young white-pine 
stock from Europe and has attained its present wide distribution 
here in such imported stock. See figures 2 to 12, showing the progress 
of the disease since 1909. : | 


INSECTS AND OTHER ANIMAL FACTORS. 


Various animals (insects, snails, mammals, man, etc.) may aid in 
the distribution of the disease by carrying spores on their bodies, or 
they may retard or reduce the fruiting of the fungus by eating the sori 
on both pines and Ribes; and others such as gipsy-moth larve, other 
insects, snails, and squirrels may even eat the surrounding bark on 
pines, so that no more sori can form. (Pl. IiI.) In 1918, Penning- 
ton™ estimated that the production of xciospores in the Adirondacks 


4 Pennington, L.H. Op. cit. 


WHITE-PINE BLISTER RUST. Tb 


was reduced about 15 per cent by the eating of infected bark by mice, 
squirrels, porcupines, etc. Posey and Gravatt’ found that squirrels 
had eaten 17 per cent of the ecia-bearing bark in a given area at 
Kittery Point, Me., and this is substantially true for the infected 
forests of that section. The leaf-eating insects and mammals may 
so reduce the leafage of Ribes plants as to reduce the disease materially 
in a given locality. 


OTHER FUNGOUS. FACTORS. 


Other fungi are of some importance also. At Kittery Point, Me., 
Colley (20) and Posey and Gravatt*> found that secondary fungi 
work in the pine bark infected by Cronartwwm ribicola in such a way 
as nearly or entirely to kill out the latter, probably by killing the 
bark around the cankers so that the blister rust is starved out. This 
sort of thing is quite general where white pines are generally infected 
by Cronartium ribicola. Very often it appears that the diseased 
pines are killed finally by the secondary fungi rather than by the 
blister rust. The ecia of Cronartvwm ribicola are sometimes attacked 
directly by other fungi (80, 168, 172). It has also been found that 
the uredinia and telia are attacked by various fungi, so that their 
efficiency is greatly reduced locally (116). Fungi parasitic upon the 
leaves of Ribes sp., causing their premature fall, may greatly reduce 
the leafage available for the blister-rust fungus to attack and thus 
reduce the quantity of teliospores to produce infection on pines. 


FACTORS IN THE HOSTS. 


There are certain factors in the hosts themselves which are impor- 
tant in the contro! of this disease where it has once become estab- 
lished. These are resistance by some of the hosts to the disease and 
the natural suppression of the lower branches of white pines. 

Among the white pines the blister rust attacks Pinus strobus with 
especial virulence. It does not attack P. cembra nearly so readily. 
Experience shows that P. flexilis ** is decidedly susceptible to 
it. This is confirmed by Moir’s studies in Sweden. Knowledge of 
the relative susceptibility of the pines is extremely limited, because 
the disease has been in North America too short a time and has not 
yet reached any but the eastern white pine. In Europe, where the 
older outbreaks have occurred, there undoubtedly is an opportunity 
to obtain definite data on the relative susceptibility of the pines. 
It may prove feasible ultimately to plant another species of white 
pine which is not nearly so susceptible to the blister rust and which 
also is of value as a timber tree. 

55 Posey, G. B., and Gravatt, G. F. Field studies on the white-pine blister rust at Kittery Point, Me. 
Seen in manuscript. ' 


56 Pennington, L. H., Snell, W. H., York, H. H., and Spaulding, P. Investigations of Cronartium 
ribicola in 1920. Seenin manuscript. Published in Phytopathology, v. 11, p.170-172. 1921. 


76 BULLETIN 957, U. §. DEPARTMENT OF AGRICULTURE. 


It has been possible to learn a little more concerning resistant 
species and varieties of Ribes. Ribes alpynum is found to be immune 
in America, although it is stated that it takes the blister rust in 
Europe. There does not appear to be any resistant species which | 
will take the place of the cultivated R. nigrum (the black currant), 
or of R. odoratum (aureum) (the flowering currant). Among the 
cultivated red currants the varieties Franco-German, London, 
Rivers, and Holland have shown themselves very resistant. In 
generally infected areas these may prove of value to replace the 
more susceptible varieties. 

In the outbreak area at Kittery Point, Me., one of the oldest in 
North America, the infected pines are thickly crowded together and 
mostly range in height from 15 feet upward. The lower branches 
are being suppressed and are dying rapidly from overcrowding. 
Experience has shown that trees and branches attacked by the 
blister rust are weaker than healthy ones and are more apt to die 
from drought and suppression. Posey and Gravatt*’ find that this 
natural suppression of lower branches at Kittery Point has resulted 
in the killing of many entire branches bearing blister-rust cankers — 
well out from the trunk of the tree. In such cases the disease in the 
dead branches is killed also. They find that about 15 per cent of the 
trees originally infected have thus recovered from the disease before 
it reached their trunks. As above intimated, this process is probably 
at its height in this area, since suppression of the branches is ap- 
parently at its maximum. 


Experiments in Control in Europe. 


In experimenting with the white-pine blister rust, the European 
investigator has always had a different viewpoint from that of the 
investigator in North America. This has been due to two reasons— 
the disease was possibly native in Kurope, certainly in Asia, but was 
introduced into North America; Pinus strobus, the favorite pine host 
for the fungus, is native in North America and introduced into 
Europe. That is, the situation is exactly reversed in every respect 
in North America as compared with Europe. 

The disease is generally considered to have been native in the 
Alps and in the Ural Mountains upon Pinus cembra. It appeared 
in widely separated localities through Northern Europe before plant 
pathology had developed to any extent. That is, organized quaran- 
tines, present methods of spraying, and many other methods now 
used ‘in fighting plant diseases were unknown at that time. The 
fact that the disease was prevalent practically throughout northern 
Europe before it became generally known, showed plainly that it 
was firmly established throughout that region. This meant that 


57 Posey, G. B., and Gravatt, G. F. Op. cit. 


d 
. 


Pe ee eS 


WHITE-PINE BLISTER RUST. rag 


eradication was impossible. Local control has therefore been the 


only aim of the Europeans. Besides all this, the application of 


methods of control to plant diseases in Europe has never been devel- 
oped to such a point as it has in North America except for relatively 
few diseases of the more important cultivated crops. There has 
apparently never been a well-planned investigation of the control 
of this disease extending over a number of years anywhere in Kurope. 
All European publications upon control are fragmentary. It is 
evident that many scattered efforts have been made to control the 
disease there, but the results have never been published. 

As stated above, the status of Pinus strobus in Europe is entirely 
different from its status in North America. While it has been more 
than 200 years since it was introduced into Kurope (5), 1t of course 
has not approached the distribution that a tree does in its native 
region. It has been widely distributed in Europe as a park and orna- 
mental tree and has been very popular for this purpose. As a forest 
tree it is a species which is planted in relatively small blocks and even 
then only on an experimental scale. In Europe it is essentially an 
ornamental tree rather than an important timber tree. Its total 
value there is exceedingly small compared to its total value in North 
America. 

Legislation against plant diseases in Europe is so complicated that 
no attempt will be made here to give an outline of it. Incidentally, 
it should be stated that Tubeuf (162, 163, 164, 169, 170, 174) has 
repeatedly called attention to the fact that commercial nurseries 
have been and are still spreading this disease throughout Germany. 
In 1904 he (170) repeats earlier demands for a national control of 
the forest-tree nursery trade and goes so far as to refute the state- 
ments of Schwarz (125) that this disease in the nurseries at Halsten- 
bek is absent or negligible. Itis evident that the nursery trade domi- 
nated the situation and prevented such action. 

Since the disease on Ribes plants is essentially one of the leaves, 
there has been an apparent chance for success by spraying them. 
Tubeuf (165) seems to have been the first to report on such tests. 
He sprayed Ribes leaves in the greenhouse with Bordeaux mixture 
and then set the sprayed plants among those already diseased. 
Numerous uredinia soon developed on the lower sides of the sprayed 
leaves. Jaczewski (58) says that spraying with Bordeaux mixture 
is not very effective. 

Ewert (37) in 1912, to prove whether infection of Ribes leaves 
always occurs on the lower side only, made a test on a bush of Ribes | 
mgrum. This bush was one of a number of Ribes plants upon which 
Cronartium ribicola had appeared every year for a decade. One-half 
of the bush was sprayed on the lower sides of the leaves only; the 
other half was untreated. Spraying was done on March 28, April 9 


78 BULLETIN 957, U. S. DEPARTMENT OF AGRICULTURE. 


and 27, May 3, 7, and 20, Junel, and July 9. About 1,000 leaves were 
borne on the bush on June 27 so that each half had approximately. 
500 leaves. At that time the unsprayed half had about 250 leaves 
so heavily infected on the lower surface that some were already 
about to fall. On the sprayed half only 10 leaves were infected, all 
but one of these had only 1 or 2 sori, a single leaf had more. In this 
season the fungus attacked all the Ribes bushes very heavily, more 
so than for 10 years preceding. 

It is noted that Ewert does not say specifically that sori formed only 
on the lower surface of the leaves. They may be presumed to have 
done so. 

On April 26, 1918, Ewert placed four potted plants each of Ribes 
nigrum, R. aureum, and R. rubrum (var. Red Holland) around a tree 
of Pinus strobus heavily infected with Cronartium ribicola. On 
April 26, May 9, 17, and 24, June 6 and 21, and August 8, the several 
plants of each species were treated as follows: 

Plant 1, sprayed with 1 per cent Bordeaux mixture on only the upper surfaces of 
the leaves. 

Plant 2, sprayed with 1 per cent Bordeaux mixture on only the lower surfaces of 
the leaves. 

Plant 3, sprayed with 1 per cent Bordeaux mixture on both surfaces of the leaves. 

Plant 4, untreated check plant. | 

The checks on May 17 had two leaves with a considerable number 
of uredinia; on May 25 almost all leaves bore uredinia; and on July 
28 there were 50 heavily infected leaves. 

Plants numbered 1 (sprayed on the upper surfaces only) on May 
25, showed the first uredinia on one leaf; on June 3 six leayes were 
infected, two very heavily; on July 28 there were 50 infected leaves. - 

Plants numbered 2 (sprayed on the lower surfaces only) on June 
3 first showed very slight infection on two leaves; on Huby 28 four 
leaves were infected, all lightly. 

_ Plants numbered 3 (sprayed on both upper and lower surfaces) on 
July 24 were healthy. On June 28 one leaf bore a single uredinium. 

Here again Ewert fails to state definitely whetner or not the 
infections were all on the lower surface of the leaves. 

Ewert’s experiment of 1912, spraying one-half of a Ribes nigrum 
bush, was repeated in 1913. In this case the sprayed leaves re- 
mained healthy, except where they were not thoroughly reached 
with the spray. This exception seems to the writer to be signifi- 
cant, as it indicates that spraying carefully enough to control the 
disease was apparently not practicable even for as painstaking an 
experimenter as Hwert showed himself to be in planning and carry- 
ing out these tests. In 1912 the disease was very virulent, while 
in 1913 it was not. This probably largely explains the better show- 
ing made in 1918 in these experiments. Although spraying greatly 


WHITE-PINE BLISTER RUST. 79 


reduced the number of uredinia, it did not entirely prevent their 
formation. 

The spraying of pines with fungicides apparently has not received 
much attention. It is reported that the infection of young seedlings 
of white pine has been controlled by spraying in Belgium (106). 

Pines have been treated in Europe by the application of various 
chemicals, but the following cases are the only ones where results 
are given. . 

Hostermann (55) treated the affected parts of two Pinus strobus 
trees with 10 per cent and 20 per cent solutions of carbolineum. 
This was applied with a brush on April 28, 1908, before the scia 
matured, and again on May 12 and 18. The next spring, ecia started 
to develop, and the treatment was repeated with a 50 per cent solu- 
tion of carbolineum. The tree was apparently unhurt, but in the 
spring of 1910 the fungus was still alive. 

In another case (102), where 15-year-old trees were badly attacked 
on the trunk and the leaves had turned noticeably yellow, the bark 
was scraped off and the area bandaged with ‘‘carbolineum avena- 
rius.”’ A second tree was scraped and a 10 per cent solution of 
potassium permanganate applied. On a third tree a 1 per cent 
solution of copper sulphate was used. The first and second trees 
recovered and the last one died. 

Bittner (9) treated 18-year-old Pinus monticola trees which had 
trunk infections. Attempts at cutting out the infections failed. 
He then applied “tree wax”’ to the visible infection itself and 20 cm. 
above and below it. The trees showed no blister rust in 1906. It 
would be interesting to learn if this held true for several years. 

Eriksson (33) recommends the use of tar to cover the infections 
and prevent the distribution of the spores. 

Tubeuf (164) says that valuable trees may be saved by cutting 
out infections and treating with lysol, asphalt, etc., if Ribes are 
removed for a distance of 50 meters, so that no new infection can 
occur. | 

Kneiff (74) removed blisters by frequent wet rubbing. He also 
used “‘tree wax’’ and cloths wet with carbolineum. These hindered 
the disease, but he says the best way to fight it is the removal and 
burning of the diseased parts or plants. 

Pechon (105) advises burning affected trees and states that treat- 
ment with tar and similar substances will not suffice. 

Kohler (75) tried cutting out and smearing, but gave up these 
methods as causing too much injury and even death. He sprayed 
the trunks with a strong stream of water before the blisters opened 
in the spring. The blisters disappeared and the trees formed new 
bark. 


80 BULLETIN 957, U. S. DEPARTMENT OF AGRICULTURE. 


Fungi which parasitize Cronartium ribicola are not uncommon. 
Their use in artificial inoculation of infections on pines has been 
attempted (172, 173, 174), but with little success. There appears — 
to be little prospect for success commensurate with the expense — 
involved. | 

The separation of the pines from the Ribes plants is the most 
efficient method of controlling the disease in a given locality. To 
judge from the frequency of this recommendation for combating 
the disease in European literature, apparently considerable work of 
this kind has been done in Europe; but no definite statement of 
results in specific instances have been found. 

The use of screens of another species of tree between Ribes and 
Pinus strobus has been recommended in Europe (131, p. 41). No 
one has stated the results of such treatment in any given instance, 
however. | 

There must be a chance to secure much valuable data on the 
success or failure of various methods of treatment which have been 
tested in Europe, but which have never been published. This can 
only be done by making definite investigations in Europe from the 
American standpoint. It must be remembered that from the 
Kuropean point of view the white pine is an introduced and com- 
paratively unimportant tree. Its diseases, therefore, are not made 
the subject of systematic and prolonged study. Many facts of value 
fundamental to the control of this disease in America can only be 
determined by the intimate study on the ground of the much older 
infections of Europe. 


Experiments in Control in North America. 


In all control of parasitic plant diseases the fundamental thing is 
to determine the extent and the distribution of the disease to be 
controlled. The parasitic fungi are so generally distributed by the 
wind and are so insidious in their spread that they usually have 
gotten well started before their presence is discovered. Newly dis- 
covered imported diseases must be attacked at once or not at all, - 
if eradication is to be accomplished, but more attention should be 
given to the matter of determining reliably the extent of outbreaks 
of such diseases. Scouting is a very important part of any disease 
eradication or control campaign. A _ well-conducted, imtensive, - 
plant-disease survey will do much to aid in determining the status 
of a new disease. 

METHODS USED. 


The control of white-pine blister rust has been attempted in 
North America (1) by means of quarantines of the host plants, — 
(2) by the eradication of advance infections, (3) by the separation ~ 
of the two hosts, (4) by sanitation, (5) by screening Ribes or pines _ 


WHITE-PINE BLISTER RUST. 81 


with other species, (6) by the judicious selection of planting sites for 
pines, and (7) by such minor methods as spraying, close pasturing 
of Ribes, and the removal of the diseased plants or parts of them. 


QUARANTINE. 


In North America (131, p. 54-55), Canada took the first official 
action against the white-pine blister rust, placing it on her list of 
proscribed plant diseases and later prohibiting the entry of all 
5-leaved pines from 
all other countries. 
Since then (2) a quar- 
antine has been de- 
clared against the 
shipment of Ribes 
from points east of a 
line between Saskat- 
chéwan and Alberta 
to points west of that 
line. Theshipment 
of Ribes to points 
west of this line is 
allowed from points 
in the United States 
south of the above 
protected area. 
These modifications 
are made to help 
protect the western 
white-pine areafrom 
the shipment of this 
disease in nursery 


stock,and to connect 


with the Mississippi Fic. 13.—Outline map of North America, showing the quarantine 
lines established by the United States Department of Agriculture to 


Valley quarantine control the white-pine blister rust by prohibiting the shipment of the 
line in the United host plants from infected territory to uninfected sections. The 
Ss : bik quarantine line established by Canada to prevent the shipment of 

tates, WIC as diseased nursery stock across the prairie region from the eastern 
been established Provinces is also shown. 


with this end in view (fig. 13). The United States Government in 
1912 (94) put in force a regulatory act controlling the entry and 
movement of nursery stock. This act prohibits the entry of 5-leaved 
pines and of Ribes from Europe, Asia, and Canada; forbids the 
shipment of such stock from the eastern section of the country to 
points west of the western boundaries of the States of Minnesota, 
Iowa, Missouri, Arkansas, and Louisiana; and also forbids the 
46103°—21—Bull. 9576 


82 BULLETIN 951, U. S. DEPARTMENT OF AGRICULTURE. 


shipment of 5-leaved pines and of Ribes nigrum from the States 
of New England to any of the other States and from New York to” 
points outside that State. Still more recently, an absolute embargo 
has been placed on ornamental and forest tree and shrub stock from 
other countries (fig. 13). 

These quarantines prevent our getting more of the white-pine 
blister rust from other countries. ‘The Great Plains region forms a 
natural barrier (fig. 13) against the spread of this disease from the 
East to the West (97, 98, 141, p. 7; 148)). Since it is already well 
distributed and established east of this barrier, the immensely 
valuable western white pines can be protected very efficiently by 
preventing the shipment of white pines and Ribes from the infected 
section to the western region, which is still free from the disease. 
This is accomplished by quarantine, which is designed to prevent the 
shipment of infected stock from a generally infected district to those 
States which are not generally infected and to exclude plant pests © 
from all the rest of the world (98). | 

Within the past four years many of the various States have — 
enforced regulatory measures with reference to this disease (94). — 
These States are California, Delaware, Georgia, Idaho, Illinois, Indi- ~ 
ana, Kansas, Maine, Maryland, Massachusetts, Michigan, Minnesota, 
Montana, Nevada, New Hampshire, New Jersey, New York, North 
Carolina, Oregon, Pennsylvania, Rhode Island, South Carolina, 
South Dakota, Tennessee, Vermont, Washington, West Virginia, 
and Wisconsin. 


ERADICATION OF ADVANCE INFECTIONS. 


In 1909, when Cronartiwm ribicola was first found upon white pines — 
in North America, it appeared to occur only on recent shipments of 
young trees from Europe. That is, it was present in advance infec- 
tions, and so far as could be determined there was no generally | 
infected area. Since that time areas have been found which are 
generally infected, and we have both types of infections to reckon 
with. (See figs. 2 to 12.) Where advance infections were small it” 
appeared to be feasible to attempt eradication of the disease, but 
when generally infected areas were found eradication became impos-_ 
sible, and local control was the only feasible thing to be attempted. — 

When this disease was first discovered on Ribes in 1906 at the © 
Agricultural Experiment Station at Geneva, N. Y., an attempt was 
very properly made to eradicate the disease. All of the Ribes in the | 
infected plat were destroyed. Very few white pines were within 
half a mile, and none of these were found diseased. Stewart (150) 
published an excellent account of this case. It was not then known 
that the eciospores readily blow for miles in a viable condition, nor 
was that fact established until rather recently (128, 145, 146). 


WHITE-PINE BLISTER RUST. 83 


In 1909 it was learned that great quantities of infected young white 
pines had been imported from Europe in 1907, 1908, and 1909. 
(Fig. 1.) With conditions as they appeared to be, it was believed 
that eradication might be possible, and this was attempted. The 
disease was held in check in such shipments of diseased trees as 
could be located. But many could not be located. Moreover, for 
years before, as was subsequently learned, nurserymen and private 


- individuals had imported from Europe many infected white pines. 


pre a ata =e ~ 
: 


These we had no means of knowing about until too late, since the 
importers and planters did not inform us concerning them, even after 
the publication of warnings against the disease. Such diseased im- 
portations have been the centers from which most of our large out- 
breaks have started. So far as we can learn no Federal agency has 
imported white pines upon which this disease has been found. 

More complete knowledge of the life history of the fungus has shown 
that it is impossible to eradicate it where both Ribes and white pines 
are native and abundant, after the eciospores are once set free in 
quantity. If both pines and Ribes be removed from a given area 
the disease may be eradicated in that area but it will have escaped 
beyond that area by means of the eciospores. This happened in 
Minnesota and Wisconsin, where all the white pines and Ribes were 
removed from large infected areas. 

The removal of pines has been accomplished in a few cases. Entire 
plantings of imported pine stock were destroyed soon after they were 
found to be diseased, and in these cases Ribes were also removed or 
were absent from the area treated. The forestry officials of the State 
of New York took the lead in this work, destroying 1,200,000 imported 
trees in their nurseries in 1910 and 1911. A number of plantations 
were also destroyed in New York, New Jersey, and Vermont (131, 139). 
As early as 1912, the total destruction of diseased lots of imported 
white pines (133) was urged rather than weeding out only those 
which were visibly diseased. Public opinion would not permit this 
to be done in the wholesale manner that was necessary for efficiency. 
Yet this was the one efficient manner of handling such imported trees 
(136) before generally infected areas had developed. 


SEPARATION OF THE TWO HOSTS. 


The fact that each form of spore will infect but one of the hosts, at 
once indicates that a separation of these hosts will prevent the further 
progress of the parasite within the control area. If the pines only 
are removed, the disease will be likely to die out on the Ribes, since 
it apparently overwinters on them only infrequently; if the Ribes 
are removed, the disease is isolated on that particular lot of pines, 
where it overwinters (if the diseased trees are not also found and 
removed) and produces new crops of zciospores each spring. The 


84 BULLETIN 957, U.S. DEPARTMENT OF AGRICULTURE. 


disease is kept from attacking more pines within the area where the - 
Ribes are removed, but it may spread to Ribes miles away, there to 
start new pine infections, each of which will act as a new center of in- 
fection in future years. This makes it practically impossible where 
both white pines and Ribes are native entirely to eradicate the disease 
after the zeciospores are once set free. 


REMOVAL OF PINES. 


In all work where pines have been removed the Ribes have been 
absent or were also removed; hence, all this work is placed under 
‘Eradication of advance infections.’’ In some of the States, Ribes- 
erowing sections are being established, and it is expected that 
white pines will be entirely removed from such areas. 


REMOVAL OF RIBES., 


Experiments on a large scale are in progress in all of the States of 
New England and in New York, Wisconsin, and Minnesota for the 
removal of all Ribes in certain areas, to determine whether it is 
practicable thus to protect valuable white-pine stands. 

Much work of this sort has been carried on during the past four 
years. Infected areas have been chosen and the Ribes removed 
under various conditions to show what possibilities there are in 
such work (23, 24, 25, 103, 104). The removal of all Ribes plants 
in a given area is a difficult matter. Wild Ribes offer the greatest 
difficulties. It is not humanly possible to find every plant in wild 
woodland; plants pulled up, if left touching the soil, may again take 
root and persist in a living condition; pieces of root crown and oc- 
casional pieces of roots left in the soil sprout and make new plants 
(23, p. 8); fruits on the pulled bushes fall off and start a crop of 
seedlings to replace the parent plant; seeds of old fruits already on 
the ground may germinate and start seedlings. Nevertheless, the 
results of this work are encouraging. Wild currants and goose- 
berries do not reproduce rapidly in an area that has been worked 
by an efficient crew. Thorough checking on 2,485 acres in 8 separate 
tracts previously gone over by eradication crews showed that on an 
average acre, 62 bushes (95.5 per cent) were destroyed in the first 
working and 3 bushes in the second working. Of the latter, two 
bushes were missed in the first working and one bush developed 
from seeds or sprouts. The remaining plants are so small that they 
carry but 1 to 2 per cent of the total. Ribes leafage (24). Moreover, 
they are usually so low or so covered with other vegetation that very 
few become infected, so that the work results in almost perfect con- 
trol of the disease. To judge from data at hand, control areas usually 
should be reworked within 10 years after the first working (25). | 

Two principal methods of removing Ribes have been developed. — 
Where Ribes are abundant the Ribes eradication crew has to cover 


WHITE-PINE BLISTER RUST. 85 


all the ground and pull the Ribes as they go. Where Ribes are 
relatively scarce they are likely to occur only in certain favorable 
locations. In such territory an expert scout covers the ground, 
mapping it and indicating the Ribes areas to be worked by the crew. 
In favorable localities this has proved successful and greatly reduces 
the cost of Ribes eradication (25). Experiments in the killing of 
thick stands of wild Ribes with chemicals indicate that this method 
(113) materially reduces the cost. 

Ribes eradication was started as early as 1909, but at that time 
was limited to plantations of infected imported ee pines and to 
a safety belt of 100 yards around them. In 1910, the width of the 
safety belt was increased in some of the States to 500 feet, and in 
1915 in Massachusetts to 500 yards. In 1916, 600 yards was taken 
as the safe width for all situations. Prior to 1919, facts concerning 
the spread of Cronartium ribicola from Ribes to pines were not 
definitely known. As a result of the investigations of the germina- 
tion and dissemination of the sporidia the width of the Ribes-free 
zohe was set, in 1919, at 200 to 300 yards for average conditions 
(25, 146). 

In 1917, when extensive areas were first cleared of all Ribes, lack 
of experience in such work by all connected with the work greatly 
reduced its efficiency, but even then it was found that the outlook 
was not hopeless, although the cost of eradication of Ribes was too 
high to be justified except where pine stands were valuable. Efhi- 
ciency has been steadily increased since then until it has been found 
that men green in this work can be quickly taught to find and destroy 
at least 95 per cent of all wild Ribes plants the first time over the 
ground (24, 25). A system of checking the work has been developed, 
as well as a system of accounts, so that present results are quite ac- 
curately known. 

The cost of Ribes eradication has been steadily reduced. In 1918, 
105,977 acres were worked in New England at a labor cost of 44 cents 
per acre. In New England and New York the average cost per acre 
Including supervision in 1918, was 66 cents. In 1919, in New York 
and New England, 252,114 acres were worked at an average cost per 
acre of 54 cents, including supervision, and of 42 cents for actual 
labor (24, 25). Improved methods are expected to reduce still 
- further this cost as, in New England alone, the cost in 1919 was 24 
cents per acre, owing to the use of improved methods (24). 

The efficiency of Ribes eradication with respect to pine infection 
will become evident as time elapses. Examination of areas where 
Ribes were eradicated in 1916 and 1917 has shown no new pine 
infections. This is in spite of the considerable number of Ribes 
 Inissed in the early work. | 


\ , 


86 BULLETIN 957, U. S. DEPARTMENT OF AGRICULTURE. 


The experiments in the removal of Ribes on an extensive scale 
have gone far enough to prove that it is a practical method of pro- 
tecting pine stands. Accordingly the public has been urged to des- 
troy wild and cultivated Ribes within at least 200 yards of valuable 
pine stands in the generally infected regions. 

Assistance to individual pine owners, towns, and associations in protecting pine 
areas from the blister rust is given by the New England States, New York, Wisconsin, 
and Minnesota, in cooperation with the United States Department of Agriculture. 
In 1919, about $10,000 was subscribed for cooperative eradication of currants and goose- 
berries by individuals and associations in New York. In Massachusetts, local coop- 
erators furnished $1,075. In New Hampshire, 53 towns voted appropriations totaling 
$8,514, and 34 individuals and firms subscribed $2,053 additional. The interest of the 
public in blister-rust control is further evidenced by the fact that this State destroyed 
21,171 bushes of cultivated currants and gooseberries belonging to 1,023 owners, and 
only 8 owners insisted on compensation for their bushes (24). 

The State and Federal authorities favor cooperation with towns, 
counties, associations, or groups of individuals in order to free from 
Ribes as large an area as possible in each locality. This reduces cost 
per acre and increases the effectiveness of the protection to pines. 


SCREENING RIBES AND PINES WITH OTHER SPECIES. 


Screens of heavy underbrush or trees surrounding or covering 
Ribes will do much to prevent infection of the Ribes by sciospores 


and will greatly reduce infection of white pines, if the Ribes do be- — 


come infected (145, 146). 

Screens or windbreaks of other kinds of trees around the edge of 
white-pine stands will greatly reduce infection on the pmes. In the 
same way, planting in mixture or ih strips alternating with another 
species should help to keep the disease down. | 

SELECTION OF SITES FOR PINES. 


Infection by Cronartvum ribicola may be reduced to a minimum in a 
generally infected area by judiciously choosing a site for the planting 
or natural seeding of white pines. Areas where there is a minimum 
number of Ribes, or where they have been eradicated, which are not 
in moist locations and are not especially subject to fogs or mists, and 
which are protected by forests or conformations of the land from 
heavy sweeping winds, are favorable for the encouragement of the 
growth of white pines. The converse conditions are to be avoided 
as far as possible. 

SPRAYING. 


Spraying has been little used in North America to control the white- 
pine blister rust, as the chances for success have appeared to be 
slight. Spraying of Ribes to prevent their infection has been tested 
in a number of instances. © 

In 1915, McCubbin (86) carried on some careful spraying tests with 
Ribes nigrum plants, using both Bordeaux mixture and soluble sul- 


—_— a a 2 


WHITE-PINE BLISTER RUST. 87 


phur in parallel experiments. The following statement has reference 
to spraying that was done every two weeks through the summer: 


It was realized that the spray would have to be applied to the under sides of the 
leaves to be effective, and though this was done as thoroughly as possible in our work, it 
must be admitted that it takes somuch time and care that satisfactory spraying of this 
kind would be out of the question inacommercial way. Owing to frequent rains dur- 
ing the summer, the best results were not obtained from this work, but even allowing 
for this it was certain that, though the rust'can be greatly reduced by spraying, it can 
not be controlled sufficiently to prevent the spread of infection. Consequently, what- 

‘ever value spraying methods may have as a means of protecting individual planta- 


- tions, they are likely to be of little use in combating the disease as a national pest. In 


this connection, it has been suggested by the Dominion Botanist that since spraying 
will not completely control the rust, it may work a positive harm by keeping the in- 
fected leaves longer on the bushes in the fall, and thus materially extend the period 
during which infection of the pine may take place, providing, of course, that the in- 
fection of pines is possible throughout the whole season. 

Stoddard, in 1918 (23), carried out aspraying test in Connecticut, 
with the following results: 

Spraying experiments for the control of the blister rust were conducted on red and 
black currants. Results were nearly negative on red currants because of lack of in- 
fection. On black currants spraying gave nearly complete control throughout the 
season. However, such careful and frequent spraying had to be done that it is not 
considered to be a practical method of control. | 

No experiments have been made in the spraying of pines, as it has 
appeared useless in larger trees where the infections have occurred. 
Seedlings in seed beds of nurseries may perhaps be protected from in- 
fection by: spraying, as has been suggested by Clinton and McCormick 
(14). Itshould be well tested under extreme conditions (106). 


CLOSE PASTURING OF RIBES. 


The use of animals to feed on the leaves of Ribes is feasible if the 
area is pastured heavily until well cleaned up. Sheep are very close 
feeders and undoubtedly can be thus utilized (23, p. 7). Goats are 
the most promising animals for the purpose, however, as they are 
omnivorous feeders. This method can be recommended only for 
areas where small pines are absent or too few to be of value. 


REMOVAL OF DISEASED PARTS AND DISEASED PLANTS OF RIBES. 


The removal of the infected leaves has been attempted in a few 
lots of Ribes nagrum in nurseries, but it is costly and merely palliative 
in that it is usually only postponing more drastic measures. The 
cutting back of infected Ribes bushes has been tested in a few 
instances, but like the plucking of the leaves, it is usually unsatis- 
factory, since the bush remains to take infection another season. 

The removal of diseased plants only of Ribes is unsatisfactory, 
asit has been found that it requires repeated visits through the season 
for the removal of plants which have developed the disease since 


88 BULLETIN 957, U. S. DEPARTMENT OF -AGRICULTURE. 


previous inspections. This makes the cost of the work prohibitive, 


and the disease progresses in spite of it. 
REMOVAL OF DISEASED PARTS AND DISEASED PLANTS OF PINES. 


The removal of diseased parts of infected pines does not appear to 
be an economical procedure from the viewpoint of the lumberman or 
wood-lot owner, because of the low value of single trees. For highly 
valued ornamental trees it becomes possible financially. Under such 
conditions, the removal of all Ribes to prevent new infecton, accom- 
panied by careful cutting out of all infections in the pines for several 
years, will finally result in the elimination of the disease from those 
trees. Martin, Gravatt, and Posey * have investigated the possi- 
bilities of this type of work. They conclude that— 

Experimental and practical results show that ornamental pines which have already 
become diseased can be saved by cutting out the infected parts if treatment is applied 
in time. The work is easily performed at a comparatively low cost. Treatment can 
be given any time during the year, but best results will be obtained from April to June 
when the cankers are more easily found because of the bright orange-yellow blisters. 
Successful treatment depends primarily upon ability to find the cankers and deter- 
mine accurately the edge of the diseased area. The workmen should be thoroughly 
familiar with the symptoms and appearance of the disease on pines. 

Where the Ribes can not be thus eradicated, other species of trees 
should be planted to take the place of the white pines. Cutting out 
infections depends, for success, on finding all of them. The work- 


man must be familiar with the blister rust and be thorough or the. 


results will not justify the cost. If a tree is nearly girdled near the 
eround, or if most of the branches must be removed, it is useless to 
attempt to save it. The cutting out must be repeated for several 
years after all the Ribes are eradicated, as dormant and slightly 


developed infections become visible. Cutting out experiments 


showed that cutting back for 14 inches or more from the extreme 
edge of the infected area insured removal of all diseased bark and stop- 
ped the disease in those areas. In practice this distance should be 
increased to 5 or 6 inches to insure thorough work. 

On a main trunk an infection which has extended only part way 
around the trunk may be treated by peeling off the bark on the canker 
and to the required distance around it. In this case the safety zone 
should extend for 4 or 5 inches directly above and below the diseased 
area but need not extend more than half as far sidewise. 

The removal of only diseased white pines in infected imported 
trees has been inefficient and costly, even where the Ribes were 
removed too. Records of such work in about 900,000 imported trees 
(136) shows that it is inefficient, although the disease has been checked 
somewhat. The cost has been great enough to have replaced the 
imported trees with healthy home-grown ones. 


8 Martin, J. F., Gravatt, G. F., and Posey, G. B. Treatment of ornamental white pines infected with 
blister rust. U.S. Dept. Agr. Cir. 177, 20 p., 12 fig. 1921. Seen in manuscript. 


Ne 


WHITE-PINE BLISTER RUST. 89 


In a region where Ribes are rare or practically absent the removal 
of the diseased pines only may serve to prevent progress of the disease. 
This allows the dispersal of zciospores and may result in scattering 
infection on Ribes miles away. In such cases it will take a long time 
to detect the escape of the fungus. In areas free from the Ribes the 
aim should be eradication rather than control of the disease, as such 
areas are the very ones where white pines should be grown in the 
future. 

In generally infected districts where Ribes are removed for some 
distance, it may pay to cut out the worst infected trees to reduce the 
crop of xciospores and thus reduce infection around the borders of 
the treated area. 


Status of the Control of White-Pine Blister Rust. 


The present status of the control of the white-pine blister rust in 
North America may be summed up as follows: 

Eradication of Cronartium ribicola is impossible except in small, isolated, advance 
infections. It should be attempted only in localities where the disease is quite lim- 
ited in distribution and well separated from the known generally infected areas shown 
in figure 2. As a national problem, control is the only feasible thing. Protection of 
uninfected or sparsely infected areas by enforcement of the present Federal quaran- 
tines is necessary, since this disease is distributed to great distances only by means of 
infected nursery stock. The western forests of white pines can be protected from the 
blister rust for an indefinite period by rigid enforcement of the Mississippi Valley 
quarantine. A single diseased shipment may undo all attempts to restrict it to the 
eastern forests. | 


In the eastern forests blister-rust infection on Pinus strobus is 
rapidly developing. A strip survey in one locality in New Hampshire 
(24) shows that one-fourth of the white pines on an area of 72 square 
miles are now infected. The areas marked as generally infected in 
figure 2 show the great increase in general pine infection. Much of 
this infection will become visible in the next three years. It is an 
insidious disease, a tree not being noticed as diseased until it is 
heavily infected. There is abundant evidence that it is destructive 
to merchantable trees as well as to younger ones. {t is just getting 
under headway. | 

Ribes nigrum is far the most dangerous species, but all Ribes are 
dangerous to white pines in generally infected areas. In such areas 
_ the disease can be controlled by the removal of all Ribes. Local con- 
_ trol depends on the removal of Ribes within white-pine areas and 
the education of the white-pine owners to remove Ribes as a routine 
part of white-pine forest management. Local control by the removal 
_ of Ribes can be taken up at any time in the future, but if the present 
_ stand of trees is to be saved action must be taken at once. 


90 BULLETIN 957, U. S. DEPARTMENT OF AGRICULTURE. 


A few years delay will mean serious loss. Itis asimple and practical precaution to 
destroy the currant and gooseberry bushes before they destroy the pines. The demon- 
strated effectiveness of this method of control justifies pine owners in uprooting currant 
and gooseberry bushes on a large scale (24). 


Those who do not do this in their pine lands and for a distance of 
200 to 300 yards outside will be likely to see a valuable asset turned 
into a liability. In areas where the white pine is an important tree 
cultivated Ribes should not be planted. A number of States already 
have laws prohibiting such planting without permission from the 
State authorities acy in areas designated and set apare as ‘‘cur- 
rant-growing districts.” 


LITERATURE CITED. 


(1) ADERHOLD, RUDOLF. 
1907. Versuche uber den Einfluss hiufigen Regens uaf die Neigung zur 
Erkrankung von Kulturpflanzen. Jn Arb. K. Biol. Anst. Land-u 
Forstw., Bd. 5, Heit 6, p. 354-360, 1 fig. 
(2) Amendment of -anaaery relating to importation and shipment of currants 
1919. and gooseberries. In Agr. Gaz. Canada, v. 6, no. 6, p. 526-527. 
(3) ArTaur, J. C. 
1907. Uredinaceee. Jn No. Amer, Flora, v. 7, pt. 2, p. 97-127. 
(4) Barctay, ARTHUR. 
1887. On the life history of a new Aecidium on Strobilanthes Dalhousianus 
Clarke. Jn Sci. Mem. Med. Officers Army India, pt. 2, 1886, p. 
15-27, pl. 2-3. 
(5) Brean, W. J. 
1914. Trees and Shrubs Hardy in the British Isles. v. 2. London. 
(6) Bonpartsgy, A. S | 
1910. Les parasites végétaux des plantes cultivées et sauvages, recueillis 


dans le gouvernement de Koursk en 1901, 1903-1905. Jn Acta ‘ 


Horti Petropolitani, t. 26, fasc. 1, p. 1-25. In Russian. 


(7) BREFELD, Oscar. 
1891. Untersuchungen aus dem Gesammtgebiete der Mj ykologie. Heft 9. 
Die Hemiasci nnd die Ascomyceten.. 156 p., 4 pl. Miinsteri W. 


(8) Bunyarp, E. A. 
' 1917. A revision of the red currants. Jn Gard. Chron. s. 3, v. 62, no. 1613, 
p. 205-206, fig. 78-79; no. 1614, p. 217, fig. 82-83; no. 1615, p. 232, 
fig. 88-89; no. 1616, p. 237, fig. 90-91. 
(9) Btrrner, G. 
1906. Uber Vertileung des Weymouthskiefern-Blasenrostes. In Mitt. 
Deut. Dendrol. Gesell., No. 15, p. 232-233. 
(10) Carteton, M. A. , 
1893. Studies in the biology of the Uredineze. I. In Bot. Gaz., v. 18, no. 
12, p. 447-457, pl. 37-39. 
(11) 1903. Culture methods with Uredinee. Jn Jour. Appl. Micros. and Lab. 
Methods, v. 6, no. 1, p. 2109-2114. 
(12) Cuinton, G. P. 
1918. Artificial infection of Ribes species and white pine with Cronartium 
ribicola. Jn Amer. Plant Pest Com. Bul. 2, ed. 2, p. 14-15. 


WHITE-PINE BLISTER RUST. 91 


(13) Crinton, G. P. 
1919. Inspection of phzenogamic herbaria for rustson Ribessp. In Conn. 
Aer. Exp. Sta. Bul. 214 (Rpt. of Botanist 1917-18), p. 423-427 


and McCormick, FLORENCE A. 
1919. Artificial infection of pines with Cronartium ribicola. Jn Amer. 
Plant Pest Com. Bul. 4, p. 12... 
(15) 1919. Infection experiments of Pinus strobus with Cronartium ribicola. 
In Conn. Agr. Exp. Sta. Bul. 214 (Rpt. of Botanist 1917-18), p. 
428-459, pl. 37-44. Literature cited, p. 456. 
(16) Courzy, R. H. 
1917. Diagnosing white-pine blister-rust fromitsmycelium. Jn Jour. Agr. 
Research, v. 11, no. 6, p. 281-286, 1 fig., pl. 31. 
(17) 1917. Discovery of internal telia produced by a species of Cronartium. In 
Jour. Aer. Research, v. 8, no. 9, p. 329-832, pl. 88. Literature 
cited, p. 332. 
(18) 1917. Pycnial scars, an important diagnostic character for the white pine 
blister rust. (Abstract.) Jn Phytopathology, v. 7, no. 1, p. 77. 
(19) 1917. Technique for the study of the white-pine blister rust. (Abstract.) 
: In Jour. Wash. Acad. Sci., v. 7, no..10, p. 314. (Proc. Bot. Soc. 
Wash., 119th meeting.) 


(20) 1918. Parasitism, morphology, and cytology of Cronartium ribicola. In 
Jour. Agr. Research, v. 15, no. 12, p. 619-660. 1 fig., pl. 48-59. 
Literature cited, p. 655-659. 
(20a) ComBeER, J. , 
1907. Pines attacked by Peridermium. Jn Gard. Chron., ser. 3, v. 42, 
no. 1074, p. 74. 


(21) Cornu, Maxime. 
1876. Ou doit-on chercher les organes fécondateurs chez les Urédinées et 
Ustilaginées? Jn Bul. Soc. Bot. France, t. 23, p. 120-121. 
(22) Covitie, F. V. and Brirron, N. L. , 
1908. Grossulariacee. In No. Amer. Flora, v. 22, pt. 3, p. 193-225. 


(23) Detwiter, S. B. 
1918. Status of white pine blister rust control in 1918. Jn Amer. Plant 
Pest Com. Bul. 2, ed. 2, p. 4-11. 


(24) 1919. White pine blister rust control in 1919. Jn Amer. Plant Pest Com. 
Bul. 4, p. 1-10. 


(25) 1920. Results of white pine blister rust control in 1919. In Phytopatho- 
logy, v. 10, no. 3, p. 177-180. 


(26) Drere., P. 
1904. Betrachtungen iiber die Verteilung der Uredineen auf ihren 
Nahrpflanzen. Jn Centbl. Bakt. [etc.], Abt. 2, Bd. 12, No. 6/8, 
p. 218-234. 
(27) Dretricu, H. A. 
1856. Blicke in die Cryptogamenwelt der Ostseeprovinzen. Jn Arch. 
Naturk. Liv-, Esth- u. Kurlands, s. 2, Biol. Naturk., Bd. 1, Lfg. 4, 
p. 261-416. 
(28) Doran, W. L. 
1919. The minimum, optimum, and maximum temperatures of spore 
germination in some Uredinales. In Phytopathology, v. 9, no. 9, 
p. 391-402, 1 fig. Literature cited, p. 401-402. 


(14) 


92 BULLETIN 957, U. &. DEPARTMENT OF AGRICULTURE. 


(29) Dospat1, LOUISE. 
1918. Overwintering of the #ciospores of Cronartium ribicola Fisher. Jn 
Phytopathology, v. 8, no. 12, p. 619. 


(30) Durr, Gi. 
1918. Some factors affecting viability of the urediniospores of Cronartium 
ribicola. In Phytopathology, v. 8, no. 6, p. 289-292, 1 fig. 


(31) Ertxsson, JACOB. 
1895. Rostsjukdom 4 Weymouthstallen (Pinus Strobus). In Svenska 
Tridgardsfér. Tidskr., 1895, no. 6, p. 87-89. . 


(32) 1895. Ueber die Foérderung der Pilzsporenkeimung durch Kalte. Jn 
Centb]. Bakt. [etc.], Abt. 2, Bd. 1, No. 15/16, p. 557-565, illus. 


(33) 1896. Einige Beobachtungen tiber den stammbewohnenden Kiefern- 
blasenrost, seine Natur und Erscheinungsweise. Jn Centbl. 

Bakt. [etc.], Abt. 2, Bd. 2, No. 12, p. 377-394. 

* (34) Evans, I. B. Pore. 
1907. The cereal rusts. I. The development of their Uredo mycelia. In 
Ann. Bot., v. 21, no. 84, p. 441-466, pl. 40-43. Literature, p. 464. 

(35) Ewert, R. 

1903. Das Auftreten von Cronartium ribicolum auf verschiedenen Ribes- 


Arten in den Anlagen des Kgl. Pom. Instituts zu Proskau. In 
Ztschr. Pflanzenkrank., Bd. 13, Heft 2, p. 92-98. 


(36) 1913. Erfolgreiche Bekimpfung des Cronartium-Rostes auf der schwarzen 
Johannisbeere. Jn Jahresber. Angew. Bot., Jahrg. 11, Teil 1, 

. p. 30-31: 
(37) 1913. Erfolgreiche Bekimpfung des Cronartium-Rostes auf der schwarzen 


Johannisbeere. In Ztschr. Pflanzenkrank., Bd. 23, Heft 8, p. 
463-476, 2 fig. 
(38) FAULWETTER, R. C. 
1917. Dissemination of the angular leafspot of cotton. Jn Jour. Agr. 
Research, v. 8, no. 12, p. 457-475, 2 fig. (1 fold.) Literature cited, 


p. 473-475. . | 

(39) FiscHEerR, EDUARD. | 
1904. Die Uredineen der Schweiz . . . 590 p., illus. Bern. 

(40) 1916. Verbreitungsverhiltnisse des Blasenrostes der Arve und Wey- 


mouthskiefer, Cronartium ribicola. (Abstract by author.) In 
Mitt. Naturf. Gesell. Bern, 1915, p. XX XIII. Original not seen. 
(41) 1918. Neueres iiber die Rostkrankheiten der forstlich wichtigsten Nadel- 
hélzer der Schweiz. Jn Schweiz. Ztschr. Forstw. Jahrg. 69, 
No. 6/7, p. 113-120. 
(42) Forses, A. C. 
1915. Occurrence of Peridermium strobi in Ireland. Jn Quart. Jour. 
Forestry, v. 9, no. 3, p. 250-251. 
(43) Frome, F. D. 
1913. The culture of cereal rusts in the greenhouse. Jn Bul. Torrey Bot. 
Club, v. 40, no. 9, p. 501-521. Literature, p. 519-521. 
(44) GaRDNER, M. W. 
1918. The mode of dissemination of fungous and bacterial diseases of plants. 
In 20th Ann. Rpt. Mich. Acad. Sci. [1917/18], p. 355-423. Litera- 
ture, p. 412-423. 


WHITE-PINE BLISTER RUST. — 93 


(45) Gravatt, G. F., and Marsnatt, R. P. 
1917. Arthropods and Gasteropods as carriers of Cronartium ribicola in 
greenhouses. Jn Phytopathology, v. 7 no. 5. p. 368-373. 
and Posey, G. B. 
1918. Gipsy-moth larvee as agents in the dissemination of the white-pine 
blister-rust. Jn Jour. Agr. Research, v. 12, no. 7. 0. 459-462. 


(47) Grove, W. B. 


(46) 


1913. The British rust fungi, (Uredinales) .. . 412 p., 290 fig. Cam- 
bridge [Eng.]. Bibliography of literature referred to . . . addi- 
tional to those quoted under the several species, p. 393-397. 
(48) Haack. F 


1914. Der Kienzopf (Peridermium pini (Willd.) Kleb.). Seine Uber- 
tragung von Kiefer zu Kiefer ohne Zwischenwirt. In Ztschr. 
Forst- u. Jagdw., Jahre. 46, Heft 1, p. 3-46, 11 fig. on 2 pl. 
(49) Hawes, A. F. 
1912. Suppression of white pine blister rust disease. Peridermium 
strobi. Jn 4th Ann. Rpt. Vt. State Forester, 1910, pp. 21-23. 
(50) Hepecock, G. G., BetHeL, ELuswortn, and Hunt, N. R. 
1918. Pifion blister-rust. Jn Jour. Agr. Research, v. 14, no. 10, p. 411-424, 
1 fig., pl. 54-57. Literature cited, p. 423-424. 


and Hunt, N. R. 
1920. Notes on Peridermium harknessii. Jn Phytopathology, v. 10, no. 
8, p. 395-397. 7 
(52) Hennines, P. 
1902. Beobachtungen iiber das verschiedene Auftreten von Cronartium 
ribicola Dietr. auf verschiedenen Ribes-Arten. Jn Ztschr. Pflan- 
zenkrank., Bd. 12, Heft 3, p. 129-182. 


(53) 1902. Uber das epidemische Auftreten von Cronartium ribicola Dietr. im 
t Dahlemer botan. Garten. Jn Notizbl. K. Bot. Gartens u. Mus. 
Berlin, Bd. 3, No. 28, p. 172-175. 
(54). HisIncEeR, Epwarp. 
1876. Peridermium pini(Willd.) Pers. a corticola, dédande Pinus strobus. 
In Bot. Notiser, 1876, p. 75. 
(55) HOsTERMANN. 
1911. Versuch einer Bekimpfung von Peridermium pini mit Carboli- 
neum. Jn Ber. K. Girtnerlehranst. Dahlem bei Steglitz-Berlin, 
1908-9, p. 125-126. 
(56) Howirt, J. E., and McCussin, W. A. 
1916. An outbreak of white pine blister rust in Ontario. Jn Phyto- 
pathology, v. 6, no. 2, p. 182-185. 
(57) Hunt, N. R. 
1919. The ‘‘iceless refrigerator” as an inoculation chamber. Jn Phyto- 
pathology, v. 9, no. 5, p. 211-212, pl. 12. 
(58) JaczEwsk1, A. A. 
1904-08. Ezhegodnik sviedienii o boliezniakh i povrezhdeniiakh kul’- 
turnykh i dikorastushchikh poleznykh rastenii. god 1, 1903, 166 
p., 1904; god 2, 1904, 119 p., 1906; god 3, 1907, 206 p., 1908. (Biuro 
po mikologii i fitopatologii.) In Russian. For English review of 
v. 1 (Yearbook of information concerning diseases and injuries of 
cultivated and wild economic plants) by Ernst A. Bessey, see 
Jour. Mycol., v. 11, no. 78, p. 170-179. 1905. 


(51) 


94 BULLETIN 957, U. S. DEPARTMENT OF AGRICULTURE. 


* (59) JaczEwskl, A. A. 
1905. Rzhavchina smorodiny i kryzhovnika. [A rust of currants and 
gooseberries.]| Jn Listok Bor. Boliezn. i Povrezhd. Kulturn. i 
Dikor. Polezn. Rastenii, Imp. Bot. Sad. 8. Peterb., god 4, no. 7, 
p. 61-65. In Russian. 


(60) JANCZEWSKI, EDOUARD DE. 
1907. Monographie des Groseilliers, Ribes L. Jn Mém. Soc. Phys. et 
Hist. Nat. Genéve, v. 35, fasc. 3, p. 199-516, 202 fig. 
(61) Kerrr, G. W. 
1918. Inoculation experiments with species of Coccomyces from stone 
¢ fruits. Jn Jour. Agr. Research, v. 13, no. 11, p. 539-569, 3 fig., 
pl. 55-59. 
(62) KurBann, H. 
1888. Beobachtungen und Streitfragen tiber die Blasenroste. Jn Abhandl. - 
Naturw. Ver. Bremen, Bd. 10, Heft 1, p. 145-155, pl. 1. 
(63) 1888. Weitere Beobachtungen iiber die Blasenroste der Kiefern. In 
Ber. Deut. Bot. Gesell., Bd. 6, Gen. Versamml. Heft, p. XLV-LV. 
(64) 1889. Bemerkung itiber den Weymouthskieferrost. Jn Abhandl. Naturw. 
Ver. Bremen, Bd. 10, Heft 3, p. 427-428. 


(65) 1890. Neue Untersuchungen und Beobachtungen tiber die Blasenroste 


der Kiefern. In Hedwigia, Bd. 29, Heft 1, p. 27-35. 

(66) 1892. Kulturversuche mit heterécischen Uredineen. Jn Ztschr. Pflanzen 
krank., Bd. 2, p. 258-275, 332-348, pl. 5. 

(67) 1893. Kulturversuche mit heterécischen Uredineen Jn Forstl. Naturw. 


Ztschr., Jahrg. 2, Heft 2, p. 69-72. 


(68) 1895-99. Kulturversuche mit heterécischen Rostpilzen. III, VI-VII. 
Bericht (1894, 1897-98). Jn Ztschr. Pflanzenkrank., Bd. 5, Heft 2, p. 
+ 69-79, 1895; Bd. 7, Heft 6, p. 325-345, illus., 1897; Bd. 9, Heft 1, p 
14-26, 2 fig., 1899. 
(69) 1903. Kulturversuche mit Rostpilzen. XI. Bericht (1902). In Jahrb. 
Hamburg. Wiss. Anst., Jahrg. 20, 3. Beiheft, 56 p. 


(70) 1904. Die Wirtwechselnden Rostpilzen ... XXXVII, 447p.,illus. Ber 
lin. Literatur, p. IX-XXXVII. 


Crk) 1905. Kulturversuche mit Rostpilzen. XII. Bericht (1903 und 1904). 
In Ztschr. Pflanzenkrank., Bd. 15, Heft 2, p. 65-108, 4 fig., pl. 3. 
Bibliographical footnotes. 

(72) 1912-14. Pilze. III. Uredineen. Jn Kryptogamenflora der Mark Bran- 
denburg, Bd. Va, Heft 1-5, p. 69-904, illus. 

(73) 1918. Peridermium pini (Willd.) Kleb. und seine Ubertragung von Kiefer 
zu Kiefer. Jn Flora, v. 111/112, (Festschrift zum siebzigsten Geburts- 
tage von Ernst Stahl.), p. 194-207, illus. pl. 4-5. Bibliographical 
footnotes. 

(74) Knetrr, F. cE 

1910. Blasenrost an Weymouthskiefern. Jn Mitt. Deut. Dendrol. Gesell., 
No. 19, p. 269. 

(75) KOuLER. 

1909. Dendrologische Mitteilungen. Jn Mitt. Deut. Dendrol. Gesell., No. 
6, 1897, ed. 2, p. 277-279. 

(76) KOrnicke, Fr. 

1876-77. Mykologische Beitrage. In Hedwigia, Bd. 15, No. 12, p. 178-186: 
Bd. 16, No. 1, p. 1-3; No. 2; p. 17-31; No. 3, p. 33-40. 


WHITE-PINE BLISTER RUST. 95 


(77) Krankheiten und Beschidigungen der Kulturpflanzen im Jahre 1907. 

1909. Ber. Landw. Reichsamte des Innern, Heft 16, 215 p. 

(78) KupetKa, W. 

1907. Anatomia porownawcza organodw odzywczych porzeczek (Ribes). 
(Vergleichende Anatomie der vegetativen Organe der Johannisbeeren- 
wichse [Ribes].) Jn Bul. Internat. Acad. Sci. Cracovie, Math. Naturw. 
Cl., 1907, no. 1, p. 24-40. Literaturverzeichnis, p. 39-40. Text in 
German. 

(79) Lauri, JAMES. 

1898. Diseased Pinus monticola. Jn Gard. Chron., s. 3, v. 23, no. 591, 
p. 244. 

(80) LecuMeERE, EcKLEY. 

1914. Tuberculina maxima, Rost. Ein Parasit auf dem Blasenrost der 
Weymouthskiefer. Jn Naturw. Ztschr. Forst- u. Landw., Jahrg. 12, 
Heft 9/10, p. 491-498, 2 pl. 

(81) Linp, J. ; 

1913. Danish fungi as represented in the herbarium of E. Rostrup. 648 p., 
42 fig., 9 pl. Copenhagen. List of literature, p. 555-606. 

(82) Lrro, J. I. 

1906-07. Kulturversuche mit finnischen Rostpilzen. Jn Acta Soc. Fauna 
et Flora Fennica, v. 29, no. 6, 25 p.; no. 7, 58 p. 

_ (83) 1908. Uredinese Fennice. Finlands Rostsvampar. Bidrag Kaénnedom 
Finlands Nat. och Folk, Haftet 65,640 p. Férteckning 6fver den 1 arbetet 
citerade litteraturen, p. 585-605. 

(84) McCussin, W. A. 

1917. Contributions to our knowledge of the white pine blister rust. In 
Phytopathology, v. 7, no. 2, p. 95-100, 1 fig. 

(85) 1917. Does Cronartium ribicola winter on the currant? Jn Phytopathol- 
opy, v. 7, no. 1, p. 17-31. Bibliography, p. 31. 

(86) 1917. White pine blister rust in Ontario. [Canada] Exp. Farms Rpts. 
Div. Bot. [1915]/16, p. 1099-1105. 


(87) 1918. Dispersal distance of urediniospores of Cronartium ribicola as indi- 
cated by their rate of fall in still air. Jn Phytopathology, v. 8, 
no. 1, p. 35-36. 


(88) 1918. Investigation in the Canadian Department of Agriculture. In 
Amer. Plant Pest Com. Bul. 2, ed. 2, p. 13-14. 


and Posgry, G. G. 
1917. Development of blister rust «cia on white pines after they had 
been cut down. Jn Phytopathology, v. 7, no. 5, p. 391-392. 
(90) Maenus, P. rye 
1873. Ueber die Einwanderung zweier Rostpilze, Puccinia Malvacearum 
und Cronartium ribicola. Jn Sitzber. Gesell. Naturf. Freunde 
Berlin, 1873, p. 134-138. 
(91) 1874. Ueber die Verbreitung von Cronartium ribicola. Jn Sitzber 
Gesell. Naturf. Freunde Berlin, 1874, p. 21-22. 
(92) 1902. Uber Cronartium ribicola Dietr. Jn Notizbl. K. Bot. Gartens u. 
_ Mus. Berlin, Bd. 3, No. 29, p. 183-185. 
(93) 1907. Gutes Gedeihen der nordamerikanischen Picea pungens Engelm. 
in den Alpen und Ubertritt einés einheimischen Rostpilzes auf 
dieselbe. Jn Mitt. Deut. Dendrol. Gesell., No. 16, p. 274-276. 


(89) 


96 BULLETIN 957, U. S. DEPARTMENT OF AGRICULTURE. 


(94) Martin, J. F., and Pierce, R. G. 
1919. Laws affecting currants and gooseberries. Jn U. 8. Dept. Agr 
Farmers’ Bul. 1024, p. 37-40. 
(95) MerneckE, E. P. 
1916. Peridermium harknessii and Cronartium Quekoniees te Phyto- 
pathology, v. 6, no..3, p. 225-240, 2 fig. 


(96) 1920. Facultative heteroecism in Peridermium cerebrum and Perider- | 


mium harknessii. Jn Phytopathology, v. 10, no. 5, p. 279-297, 
2 fig. 
(97) MretcaLF, HAVEN. 
1917. The control or the white pine blister rust. (Abstract.) Jn Jour. 
Wash. Acad. Sci., v. 7, no. 10, p. 313-314. (Proc. Bot. Soc. Wash., 
119th meeting. ) 
(98) 1918. The problem of the imported plant disease as illustrated by tne 
white pine blister rust. Jn Brooklyn Bot. Gard. Mem., v. 1, p. 
327-333, pl. 6-7. iA | 
(99) Naruusius, Px. von. 
1906. Kurpark Ilten bei Lehrte (Hannover). Jn Mitt. Deut. Dendrol. 
Gesell., no. 15, p. 227. 
(100) Neaer, F. W. 
1908. Ein Infektionsversuch mit Petidermiiaw Strobi von Pinus mon- 
ticola. Jn Naturw. Ztschr. Forst- u. Landw., Jahrg. 6, Heft 12, 
p. 605. 
(101) Nypets, P. 
1900. Le Peridermium du Weymouth. Jn Bul. Soc. Cent. Forest. Belg. 
v. 7, livr. 8, p. 577-579. 
(102) Observations forestieres faites en 1912. In Bul. Soc. Cent. Forest. 
1914. Belg., v. 21, livr. 6, p. 355-365. 


(103) Paun, B. H. 
[1916]. The pine blister. N.Y. Conserv. Com. Bul. 15, 18 p., illus., map., 
(104) 1918. White pine blister rust. N. Y. Conserv. Com. Bul. 15, ed. 2, 16 p., 
illus., 1 pl. (col.) 
(105) Pecnon, L. 
’ 1907. Principales maladies des arbres et des peuplements forestiers dues 
aux. champignons parasites. Jn Bul. Soc. Cent. Forest. Belg., 
v. 14, livr. 6, p. 324-332. | 
(106) [Peridermium strobi]. Jn Nature, v. 103, no. 2600, p. 513. 
1919, 
(107) Picus, G. C. 
1918. Pine blister rust scouting in Quebec. Jn White Pine Blister Rust 
Com. Suppression Pine Blister Rust in No. Amer., p. aa 


(108) Pierce, R. G. 


1917. Early discovery of whitc-pine blister rust in the United ic 


In Phytopathology, v. 7, no. 3, p. 224-225. 


(109) PLowrient, C. B. 
1882. Some observations on the germination of the Uredines. Jn Gre- 
villea, v. 10, no. 56, p. 186-142, pl. 159. 


(110) 1889. -A Monograph of the British Uredineae and Ustilagineae. .. 347 /p., 
13 fig., 8 pl. London. Authors quoted, p. 809-315. 

a Be 1899. ‘Bladder rust” of Pinus strobus. Jn Gard. Chron. s. 3, v. 26, no. 
657, p. 94. 


WHITE-PINE BLISTER RUST. 97 


(912) Posey, G. B., Gravatt, G. F., and Co.tuey, R. H. 
1917. Uredinia of Cronartium ribicola on Ribes stems. Jn Science, n. s. 
v. 46, no. 1187, p. 314- 315. 
(113) Reean, W.S. 
1919. The destruction of Ribes by chemical means. Jn Amer. Plant Pest 
Com. Bul. 4, p. 12. 
(114) Ruoaps, A. S., Hepacock, G. G., BerneL, Exrswortn, and Harriey, Cart. 
1918. Host relationships of the North American rusts, other than Gymno- 
sporangiums, which attack conifers. Jn Phytopathology, v. 8. no. 
7, p. 309-352. Literature cited, p. 346-352. 
(115) Rosrrup, E. 
1883. Fortsatte Undersggelser over Snyltesvampes Angreb paa Skov- 
traeerne. Jn Tidsskr. Skovbrug, Bd. 6, p. 199-300, 17 fig. 
(116) 1899. Ustilagineee Danie. Daanmarks Brandsvampe. Jn Festskr. Bot. 
. Foren. Kjgbenhavn Halvhundredaarsfest, 1890, p. 117-168, 12 fig. 


(117) 1891. Undersggelser over Snyltesvampes Angreb paa Skovtraaer 1883- 
1888. In Tidsskr. Skovbrug, Bd. 12, p. 175-235, 11 fig. 


(118) 1893. Anereb af Snyltesvampe paa Skovtraeer i Aarene 1891 og 1892. Jn 
Tidsskr. Skovvaesen, Bd. 5, p. 97-117. 


(119) 1895. Contributions mycologiques (V) pour l’année 1893. Jn Bot. Tid- 
sskr., Bd. 19, Hefte 3, p. 215-218. 


(120) 1902. Plantepatologi... 4 p. 1., 460 p., 257 fig. Kgbenhavn. Literatur, 
py 1-9. 
(121) Roy, Henrt. 
1918. The white pine blister rust situation in Quebec. Jn 10th Ann. Rpt. 
Quebec Soc. Prot. Plants, 1917-18, p. 25-30. 


(122) SappiIn-TRrourry. 
1896. Recherches histologiques sur la famille des Urédinées. Jn Botan- 
iste, s. 5, fasc. 2/5, p. 59-244, 70 fig. 


(123) SCHELLENBERG, D.H. C. 

1904. Der Blasenrost der Arve. Jn Naturw. Ztschr. Land-u. Forstw., 

Jahre. 2, Heft 6, p. 233-241, 2 fig. Biblographical footnotes. 

(124) ScugyEn, W. M. . 

1895. Beretning om Skadeinsekter og Plantesyedomme i 1894. 36 p. 

| Christiania. 

(125) ScHwarz, ALEXANDER. 

1903. Der Waldpflanzenzucht-Betrieb in und um Halstenbek (Schleswig- 
Holstein). Jn Forstw. Centbl., Jahrg. 47, p. 472-502. 


(126) SHaw, G. R. 
1914. Thegenus Pinus. 96 p., 39 pl. Cambridge. 

(127) Sneux, W. H. 
1919. Observations on the relation of insects to the dissemination of Cro” 
nartium ribicola. Jn Phytopathology, v. 9, no. 10, p. 451-464. 


(128) 1920. Observations on the distance of spread of eciospores and uredinio- 
spores of Cronartium ribicola. Jn Phytopathology, v. 10, no. 7, 
p. 358-364. Literature cited, p. 364. 
2 (129) SorRAvER, PAvt. 
: 1891. Peridermium Strobi Kleb. Jn Ztschr. Pflanzenkrank., Bd. 1, p. 
183, 366-367. 


-46103°—21—Bull. 957 7 


98 BULLETIN 957, U. S.‘DEPARTMENT OF AGRICULTURE. . “* 


(130) Soroxin, N. 
1876. Notiz iiber Verbreitung des Cronartium. In Hedwigia, Bd. 15, No. 
6, p. 84-87. Bibliographical footnotes. 
(131) Spautpine, PERLEY. 
1911. The blister rust of white pine. U.S. Dept. Agr., Bur. Plant Indus. 
Bul. 206, 88 p., 5 fig., 2 pl. (1 col.). Bibliography, p. 61-78. 


(132) 1912. Dangerous foreign diseases liable to be imported on plants. In 
Jour. Econ. Ent., v. 5, no. J, p. 77-80. 

(133) 1912. Notes upon Cronartium ribicola. Jn Science, n. s. v. 35, no. 891, 
p. 146-147. 


(134) 1912. Notes upon Cronartium ribicola. (Abstract.) In Phytopathology, 
VOLO ory. 

(135) 1913. The present status of the white-pine blister rust. Jn U.S. Dept. 
Agr. Bur. Plant Indus. Circ. 129, p. 9-20. Bibliographical foot- 
notes. : 

(136) 1914. New facts concerning the white-pine blister rust. U. 8S. Dept. 
Agr. Bul. 116, 8 p. Bibliographical footnotes. : 

(137) 1914. Notes on Cronartium comptoniz and C. ribicola. (Abstract.) Jn 
Phytopathology, v. 4, no. 6, p. 409. 

(138) 1914. Notes on the white pine blister rust. (Abstract.) In Phytopath- 
ology, v. 4, no. 1, p. 41-42. 

(139) 1916. Foresters have a vital interest in the white-pine blister rust. In 
Proc. Soc. Amer. Foresters, v. 11, no. 1, p. 40-47. List of publi- 
cations cited, p. 46-47. 

(140) 1916. The recent outbreaks of white pine blister rust. (Abstract.) Jn 
Science, n. s. v. 43, no. 1108, p. 487-438. Also in Jour. Wash. 
Acad. Sci., v. 6, no. 4, p. 102-103. 

(141) 1916. The white-pine blister rust. U.S. Dept. Agr., Farmers’ Bul. 742, 
15 p., 5 fig., 1 pl. (col.) 

(142) 1917. Evidence of the overwintering of Cronartium ribicola. (Abstract.) 
In Phytopathology, v. 7, no. 1, p. 58. 

(143) 1918. Results of scientific investigations. Jn White 'Pine Blister Rust, 
Com. Suppression Pine Blister Rust No. Amer., p. 37-38. 

(144) 1918. Some biological aspects of the spread of the white-pine blister rust. 
(Abstract.) Jn Jour. Wash. Acad. Sci., v. 8, no. 2, p. 40-41. 

(145) 1919. Scientific research and field investigations in 1918. Investigations 
in the United States Department of Agriculture. Jn Amer. Plant 
Pest Com. Bul. 2, ed. 2, p. 11-18. . 

(146) 1920. Scientific research in 1919 conducted by the Office of Investigations 
in Forest Pathology. Jn Amer. Plant Pest Com. Bul. 4, p. 10-11. 


_ (147) and Gravatt, G. F. 
1917. Inoculationson Ribes with Cronartiumribicola Fischer. J/nScience, 
n.s. v. 46, no. 1184, p. 243-244. 
(148) and HARTLEY, CARL. . 


1916. Safety abet in tree planting. Jn Amer. Forestry, v. 22, no. 275, p. 
665-668, illus. 
(149) Sraxman, E. C. 
1915. Relation between Puccinia graminis and plants highly resistant to 
its attack. Jn Jour. Agr. Research, v. 4, no. 3, p. 193-200, pl. 28. 
Literature cited, p. 198-199. 


WHITE-PINE BLISTER RUST. 99 


(150) Stewart, F. C. 
1906. An outbreak of the European currant rust (Cronartium ribicola 

Dietr.). N. Y. State Agr. Exp. Sta. Tech. Bul. 2, p. 61-74, 3 pl. 
Bibliography of Cronartium ribicola and Peridermium strobi, p. 
70-74. 

and RANKIN, W. H. 

1914. Does Cronartium ribicola over-winter on the currant? N. Y. State 

Agr. Exp. Sta. Bul. 374, p. 41-53, 3 pl., | map. 


(152) Stewart, V. B. | 
1917. The perennation of Cronartium ribicola Fisch. on currant. Jn 
Phytopathology, v. 7, no. 6, p. 449-450. 


(151) 


(153) Stone, R. E. 


1918. Incubation period of Cronartium ribicola on the white pine. In 
Phytopathology, v. 8, no. 8, p. 438-440, 1 fig. 


(154) Supwortn, G. B. 
1913. Forest atlas. Geographic distribution of North American trees. 
Part I—Pines. U.S. Dept. Agr., Forest Serv. 2 p., 36 maps. 
(155) Sypow, Pavt, and Sypow, Hans. 
1915. Monographia Uredinearum...v.3. Lipsiae. 


(156) TAKAHASHI, Y. 
1905-06. Notes on some parasitic fungi of Japan. Jn Trans. Sapporo 
Nat. Hist. Soc., v. 1, pt. 2, p. 169-181. In Japanese, résumé in 
English. 
(157) Taytor, MINNIE W. 
1919. The overwintering of Cronartium ribicola on Ribes. Jn Phytopa- 
thology, v. 9, no. 12, p. 575. 
(158) THAXTER, ROLAND. ) 
1887. On certain cultures of Gymnosporangium, with notes on their 
Roesteliz. Jn Proc. Amer. Acad. Sci., v. 22 (n. s. v. 14), 1886, 
p. 259-269. 
(159) THayeER, Pavt. 
1918. Notes on the nomenclature and classification of currant varieties. 
In Proc. Soc. Hort. Sci., 1917, p. 65-70. 
(160) THouvenin, Maurice. 
1890. Recherches sur la structure des Saxifragacées. Jn Ann. Sci. Nat., 
not, ac7, t.42. p. 1-174. 
(161) Tutmen, F. von. | 
1877-82. Beitrage zur Pilz-Flora Sibiriens I-V. Jn Bul. Soc. Imp. Mat. 
Moscou, t. 52, 1877, no 1, p. 128-152; t. 53, 1878, no. 1, p. 206-252; t. 
55, 1880, no 1, p. 72-104; no. 2, p. 198-233; t. 56, 1881, pt. 2, p. 
! 104-134. 
(162) TuBEUuF, CARL von. 
1897. Ueber die Verbreitung von Pflanzenkrankheitem. Jn Forstl. 
Naturw. Ztschr. Jahrg. 6, Heft 8, p. 320-325, 339-340, 4 fig. 


(163) 1898. Der Rindenblasenrost der Weymouthskiefer, eine Gefahr fiir Garten 
und Wald. Jn Prakt. Bl. Pflanzenbau u. Schutz, Jahre. 1, Heft 
1, p. 11-13, 3 fig. 

(164) 1898. Ueber die Bedeutung und Verbreitung des Weymouthskiefern- 

blasenrostes. Jn Wehnbl. Landw. Ver. Bayern, Jahrg. 88, No. 

18, -p. 327. : 


100 BULLETIN 957; U. S. DEPARTMENT OF AGRICULTURE. 


(165) TuBEuF, CARL von. 
1901. Anwendbarkeit von Kupfermitteln gegen Pflanzenkrankheiten. Jn— 
Arb. K. Gsndhtsamt. Biol. Abt., Bd. 2, Heft 2, p. 367-368. 
(166) 1901. Einige Beobachtungen tiber die Verbreitung parasitarer Pilze durch _ 
den Wind. Jn Arb. K. Gsndhtsamt. Biol. Abt., Bd. 2, Meft1, — 
p. 175-177. 
(167) 1901. Infektions-Versuche mit Peridermium Strobi, dem Blasenroste der 
Weymouthskiefer. Jn Arb. K. Gsndhtsamt. Biol. Abt., Bd. 2, 
Heft 1, p. 173-175. | } 
(168) 1901. Ueber Tuberculina maxima, einen Parasiten des Weymouthskiefern- 
Blasenrostes. .. Jn Arb. K. Gsndhtsamt. Biol. Abt., Bd. 2, 
Heft 1, p. 169-173. 


(169) 1902. Die Verbreitung des Weymouthskiefernblasenrostes. Ber. II. 
Hauptversamml. Deut. Forstver. Regensburg, Aug. 1901, p. 176- 
180. 


(170) 1904. Verschleppung des Blasenrostes beim Einkauf von Weymouths- 
kiefernpflanzen. Jn Naturw. Ztschr. Land- u. Forestw., Jahrg. 
2, Heft 4/5, p. 231-232. | 

(i711) 1914. Bekaémpfung der Ribes-bewohnendon Generation des Weymouths- 
kiefernblasenrostes. Jn Naturw. Ztschr. Forst- u. Landw., Jahrg. 
12, Heft 3, p. 137-139. 


(172) 1914. Biologische Bekimpfung von Pilzkrankheiten der Pflanzen. Jn 
Naturw. Ztschr. Forst- u. Landw., Jahrg. 12, Heft 1, p. 11-19. 
Literatur, die im Texte nicht genau zitiert ist, p. 18-19. 


(178) 1914. Neuere Versuche und Beobachtungen tiber den Blasenrost der 
Weymouthskiefer. Jn Naturw. Ztschr. Forst- u. Landw., Jahrg. 
12, Heft 9/10, p. 484-491. . 


(174) 1917. Uber das Verhaltnis der Kiefern-Peridermien zu Cronartium. II. 
Studien tiber die Infektion der Weymouthskiefer. Jn Naturw. 
Ztschr. Forst- u. Landw., Jahrg. 15, Heft 7/9, p. 274-307, 6 Abb. 


(175) TuLasng, L. R. 
1854. Second mémoire sur les Urédinées et les Ustilaginées. Jn fig. 
Sci. Nat. Bot., s. 4, t. 2, p. 77-196, pl. 7-12. 
(176) UncErR, FRANz. 
1833. Die Exantheme der Pflanzen. . . 422 >p.,7 pl. Wien. 
(177) Wertu, E. 
1916. Peridermium Strobi auf Arve. Jn Mitt. K. Biol. Anst. Land- u. | 
Forstw., Heft 16, p. 14-15. 


(178) WerrsTEIn, RICHARD VON. 
1890. Ueber Ergebnisse von Culturversuchen mit heteroecischen Ure- 
dineen. (Abstract.) Jn Verhandl. K. K. Zool.-Bot. Gesell. 
Wien, Bd. 40, p. 44. 


(279) Yorn, iy ‘Tr. 
- 1920. Late seasonal production of ecia of Cronartium ribicola. Jn Phy- 
topathology, v. 10, no. 2, p. 111. 


(180) and SPAULDING, PERLEY. . 
1918. The overwintering of Cronartium ribicola on Ribes. Jn Phytopa- 


thology, v. 8, no. 12, p. 617-619. 


O aaa 


Contribution from the Bureau of Plant Industry 
WM. A. TAYLOR, Chief. 


Washington, D. C. PROFESSIONAL PAPER August 19, 1922 


THE CONTROL OF SAP-STAIN, MOLD, AND INCIP- 
JENT DECAY IN GREEN WOOD, WITH SPECIAL 
REFERENCE TO VEHICLE STOCK.' 


By NATHANIEL O. Howarp, Pathologist, Office of Investigations in Forest 
Pathology. « ° 


(In cooperation with the Forest Products Laboratory of the United States Forest Serv- 
ice, Madison, Wis.) 


CONTENTS. 
' Page. Page. 
RUEEEOQOINCEION Soo 3 1 | Durability of stained or molded 
ws ee Eat a cS a le ila 3 ee A 42 gael cl Re ne ms SMR aking SN al aL, 17 
Other fungous organisms causing Losses due to sap-stain or mold___- 18 
surface discolorations in green tim- Control smeasureg— ar 2 ce ee seb 
ee es eee ?2 | Sammiary 22" *s — enti crt eR ioe. 50 
Factors which favor the growth of —' Literature cited _________2_ Bese f'o-s 52 
sap-stain and mold fungi________ 14 
: 
INTRODUCTION. 


During periods of transit and storage, previous to its ultimate 
manufacture, green timber containing a high percentage of sapwood’ 
often suffers considerable damage. This is particularly true during 
the late spring and summer months when deterioration brought about 
mainly through a discoloration of the sapwood, known as sap-stain, 
sometimes necessitates degrading on a large scale. This staining 
of timber has occasioned severe losses in Europe as well as in the 
United States, and many expensive investigations have been made to 
determine the nature of the stain and to discover a satisfactory 
remedy. 


1The writer wishes to acknowledge his indebtedness to Mr. C. J. Humphrey, in charge 
of the Laboratory of Forest Pathology, Bureau of Plant Industry, in cooperation with 
the Forest Products Laboratory, Madison, Wis., for facilities and for advice in outlining 
the work; to Dr. Charles Thom and Miss Margaret B. Church, of the Bureau of Chem- 
istry, for the identification of mold fungi; to Mr. H. D. Tiemann, physicist and specialist 
in kiln drying, Forest Products Laboratory, Madison, Wis., for the loan of photographs ; 
to Mr. Joseph Ashcroft, of Poplar Bluff, Mo., for cooperation in the experimental dipping 
of spokes; and to all others who, by hater ce suggestion, or criticism, have con- 
tributed to the preparation of the manuscript of this bulletin. 


75579°—22——-_1 


~ Pad nef 
7 eae 


2 BULLETIN 1037, U. S. DEPARTMENT OF AGRICULTURE. 


The molding of green timber has frequently been confused with — 
sap-stain as well as with incipient decay. However, in so far as the 
production of permanent stain or the effect upon the ‘durability of the 
wood is concerned, molding is of comparatively little importance. : 
Incipient decay catised by true wood-destroying fungi, on the other 
hand, is of great importance. : 

Wacky in the year 1918 the attention of the Office of Investigations 
in Forest Pathology was called to staining and molding occurring 
in green raw material by the wood-stock committee representing the 
National Implement and Vehicle Association and other vehicle and 
vehicle parts manufacturers through the Forest Products Labora- 
tory of the United States Forest Service, Madison, Wis. The pres- 
ent investigation arose in connection with raw hardvood stock used 
in the manufacture of escort wagons and artillery carriages. A 
large quantity of this material was at that time being sawed or — 
turned, largely from green instead of seasoned stock and shipped — 
green from the saw. In some cases it was found necessary to cull — 
severely such stock at destination, owing to the presence of mold, 
stain, or incipient decay which had developed during transit and ~ 
while in storage. In cooperation with the Forest Products Labora- _ 
tory and the wood-stock committee, a questionnaire* was sent to a 
number of the contractors for Army vehicles and parts and to pro- 
ducers of wood stock. Personal investigations were also made of 
the conditions existing at 45 mills and factories engaged in the saw- 
ing of timber, dimension stock, and veneer, or in the manufacture 
of airplanes, furniture, flooring, handles, vehicles, and vehicle parts. 
Most of these mills were located in the central and southern portions 
of the United States and were directly concerned in the production 
of war material. The object of both questionnaire and persona! 
investigations was to gain information concerning the general sani- 
tary conditions existing in the woods, railway cars, sheds, ware- 
houses, and kilns; the details of manufacture of many vehicle parts; 
the extent of deterioration occurring in green raw material; the finan- — 
cial losses occasioned thereby; and, particularly, any practical meth- 
ods of handling green wood stock that would prevent the develop- 
ment of stain and mold therein. ; 

The investigations showed that many of the firms had experienced ~ 
considerable pecuniary losses, which were due to the necessity of 
using a high percentage of green stock; to a shortage of cars, re-— 
sulting in the congestion of material in the woods and railroad 


2National Implement and Vehicle Association and other Vehicle and Vehicle Parts e3 
Manufacturers. Information Division of the Wagon and Vchicle Committee and the 
Wheel Manufacturers’ War Service Committee. Wood Stock Committee. Sap-stain and © 
mold in green lumber. Nat. Implement and Vehicle Assoc., ete., Bul... 24, 2..p,.1: digas 
1918. <A..B. Thielens, chairman. Multigraphed. 


i 


SAP-STAIN, MOLD, AND DECAY IN GREEN WOOD. 3 


yards; to lack of time for the proper air seasoning or kiln drying 
_ preparatory to shipment; and, finally, in some cases to a failure to 
‘understand the conditions necessary to safeguard the stock while 
in storage or in transit. Many of these losses due to emergency will 
__ be considerably reduced upon return to normal conditions. 

Some manufacturers consider it important that, in order to over- 
_ come losses due to checking, certain kinds of stock produced at many 
_ of the smaller mills be shipped to them in a green rather than in a 
_ partly seasoned condition. They claim that these mills, not being 
equipped for the proper drying of stock preliminary to shipment, 
make it necessary for the manufacturer to insist that material from 
such sources be shipped in a green condition to the factory, where 

suitable means for storage fae drying are maintained. ‘Close atten- 

tion must be paid to the handling of this material in transit or in 
_ storage if deterioration due to fungi is to be prevented. 

_ The necessity for a careful conservation of timber in the United 
State is becoming more and more apparent (53,2 544). Measures, 
then, that will assist in preventing or reducing losses due to fungous 

. igetacies are of importance. | 

_ This bulletin presents a brief review of our knowledge of sap- 

_ stain and mold, a consideration of the causal organisms responsible 

for such deterioration in green wood stock, the results of the new 
‘investigations, and finally a summary of some of the important meth-_ 

ods of control. 


SAP-STAIN. 


_ The “bluing,” or sap-stain, of pine timber has been observed in 
_ Europe for many years. Both Hartig (17, 78) and Frank (7/7). 
refer to it in their investigations of plant diseases. Rudeloff (36) 
_ studied the effect of blue stain on the strength of pine wood. Miinch 
(31) not only examined thesproperties of blued coniferous wood but 
also investigated the causal organisms and determined the optimum 
4 conditions aA their development in the wood. In the United States 
3 considerable attention has been given to the subject by such investi- 
gators as Von Schrenk (4/, 42, 43), Hedgecock (19, 20), Riimbold 
37, 38), Weiss and Barnum (36, 57), and Bailey’ (5). Many of the 
investigations have been made in connection with the sap- statis. of 

_ hardwoods as s well as conifers. | 


he serial numbers (italic) in parentheses refer to ‘“ Literature cited’? at the end:of 
; this bulletin. 

_ #'These two reports on Senate Resolution No, 311 by the Forest Service of the United 
~ States Department of Agriculture may be obtained from the ELH iat of Docu- 
_ ments, Government Printing Office, Washington, D. C., at 25 cents and 5 cents, respec- 
tively, per copy. 


b 
ome] Py 


4 BULLETIN 1037, U.S. DEPARTMENT OF AGRICULTURE. 


DEFINITION OF SAP-STAIN. 


The term “ sap-stain ” refers to the blue, green, brown, or red dis- 
coloration which often may be observed in the saeceoe of timber 
derived from several kinds of broad-leaved and coniferous trees. 
It must not. be confused, however, with the superficial discolorations 
produced mechanically, i. e., by collections of dirt and coal dust, by 
deposits from the drip in okey cars and sheds, or from the catenin | 
moisture in kilns. Such deposits may occur upon heartwood as well 
as sapwood. Neither should it be confused with the common blue- 
purple stain apparent when rusty saws are used on certain green 
wood, such as oak. This stain results from the reaction between the — 
tannic acids of the wood and the iron compounds from the saw. — 
Finally, it must not be confounded with the variously colored super- 
ficial growths of molds or the more or less deep seated sap-rot, with 
its brown to bleached appearance and its tendency to produce a — 
punky consistency of the sapwood itself. 

There are two quite generally recognized classes of sap-stain : (1) 
The chemical stain, said to be prada by chemical reactions brought | 
about through the agency of certain oxidizing enzyms present in the _ 
wood itself; and (2) fungous stains known to be caused by several : 
species of Fonan : 


CHEMICAL STAINS. 


Chemical stains due to enzyms cause discolorations in both the sap- _ 
wood and the heartwood of sugar pine and hard maple (Tiemann, — 
51, p. 185; also Pratt, 34, p. 305-807). Such stains develop during — 
air drying, particularly under warm and humid conditions, or in 
the kiln, and give more or less permanent discolorations to the wood, ~ 
to wit, a brown stain in sugar pine (fig. 1) and a cherry color in © 
hard maple. These defects cause degrading (34) and often result in © 
financial losses. According to Bailey (5), when freshly cut sapwood — 
of alder, birch, cherry, or red gum is exposed to the air during ex- — 
tremely warm and humid weather, chemical reactions often take place — 
and within a few hours produce colored substances in the wood. Bailey — 
(5) states that the microscopic examination of sections of such wood ~ 
indicates that the colored substance develops particularly within the — 
pith rays and the parenchyma cells. He states that certain soluble ~ 
enzyms which assist in the oxidation of organic compounds and are — 
of prime importance in the nutrition and growth of living organ- — 
isms are widely. distributed in plants and animals and may also pro- — 
duce post-mortem discolorations of certain organic compounds (see 
also Clark 8,9). Yoshida (59) discovered in 1883 that an oxidizing ~ 
ferment is responsible for the oxidation of the latex in certain species — 
of Rhus and the formation thereby of black varnish, or lacquer. — 
Investigations have also shown that discolorations in fruit juices, — 


ie a 


SAP-STAIN, MOLD, AND DECAY IN GREEN WOOD. 5 


vegetables, cereals, mushrooms, and various soft plant tissues are 
brought about through the agency of certain oxidizing ferments, the 
oxidases and the peroxidases (Aso /, 2, 3; Clark, 8, 9; Kastle, 27). 
These ferments are sometimes distinguished by the production of a . 
strong blue color in a tincture of guaiacum when used in the presence 


of oxygen or hydrogen peroxid 


(Haas and Hill, 76, p. 383). | 


Bailey (5) states that the ac- 
tivity of these oxidizing enzyms 
increases with the rise in tem- 
perature to a certain point, 


mum, and then decreases as the 
temperature is raised above this 
point. In almost every case, ac- 
cording to the same authority, 
the activity is entirely destroyed 
before a temperature of 100° C.. 
(212° IF.) is reached. He also 
states that the activity of these 
oxidizing ferments is dimin- 
ished or destroyed by certain 
antiseptics and by other chemi- 
eal substances. According to 
 As6 (1, 2), such substances as 
tannin, sodium fluorid, and so- 
dium silicofluorid, interfere 
with the color reactions nor- 
mally produced by oxidases. 
Bailey (5) notes the strong 
similarity existing between the 
_ oxidizing activities of these en- 
zyms and the chemical reactions 
responsible for certain kinds of 
sap-stain, namely, post-mortem 

_ oxidation with change of color 
_ produced by solutions in con- 


which may be called the opti- 


Fic. 1.—Board of 
chemical stain. 


sugar. pine. 


showing 
The unstained area in 
the lower half of the illustration indi- 
cates the position of .a crosser during the 


The crosser afforded pro- 
Photographed by 


kiln treatment. 
tection from oxidation. 
H. D. Tiemann. 


tact with the air and the similar variations in the activity ‘of the 


discoloring agency in relation to variations in temperature. 
_ If discolorations in sapwood are due to the activity of oxidizing 
_ enzyms, which, as has been shown, are rendered inactive by exposure 
__ toa temperature of 100° C. (212° F.), a logical prophylactic measure 


would be the submersion of timber in boiling water. Bailey ‘(5), 


_ during the spring of 1910, performed certain dipping experiments. 


6 BULLETIN 1037, U. S. DEPARTMENT OF AGRICULTURE. 


He found that when 1 by 3 by 6 inch boards of alder (Alnus incana _ 
Moench), white or gray birch (Betula populifolia Marsh), paper 
birch (Betula papyrifera Marsh), and various trees belonging to the 
rose family (Rosacez) were immersed in boiling water and then — 
stacked under cover they would remain unchanged in color. Those 
boards which had been immersed in the petting water and then 
placed in the most unfavorable conditions of high humidity and 
temperature in the open and exposed to the disodt rays of the sun 
scorched on the surface. With the exception of this superficial 
scorching, no discoloration of the wood took place. On the other 
hand, untreated boards that had been cut from the same portion of 
the tree and subjected to similar conditions of temperature and 
humidity stained rapidly. Bailey (5) found that the rapidity and 
the depth to which the. stain penetrates the wood varies with the 
temperature and the moisture, hot and humid weather being espe- 
cially favorable for the production of stain. From a consideration 
of the results obtained, he concludes that sap-stain caused by oxidiz- 
ing enzyms can be readily prevented by dipping the timber for‘a few 
minutes in boiling water. : | 

Though chemical stains give more or less trouble in kiln-dried 
maple flooring and sugar-pine lumber, the discolorations may be 
prevented to an extent by the use of comparatively low temperatures 
(120° to 125° F.) and correspondingly low humidities (50 to 70 per — 
cent; Tiemann, 5/, p. 185). Because of their limited distribution — 
and the fact that they do not impair the strength or durability of the — 
timber, chemical stains in general can hardly i considered as ere 
very great economic importance. 


ie 


Fe ed ne eee IE ee Cee ee EE RT ee ee ee 


FUNGOUS STAINS. 


The second class of stains is produced by fungi. These fungi are — 
disseminated by means of minute bodies known as spores. The 
spores may be produced in countless numbers and are blown about 
by the wind, washed along by the rain, or carried by animals, — 
particularly insects. When, under favorable humidity and tem- — 
perature conditions, they happen to lodge upon a substratum, such — 
as the moist green sapwood of woods that contain the requisite food ~ 
material, the spores may germinate and give rise to a mass of fine, — 
usually septate threads, sometimes colorless at first, but often becom-. 
ing darkened with age. This vegetative portion of the fungus is” 
known as the mycelium, and the individual threads are called hyphe. — 
In some cases the hyphe probably penetrate the wood but little, — 
growing for the most part over the surface; in others, they may enter 
the sapwood through the medullary or pith rays. » This does not result 
in the disintegration of the walls of the wood cells to any appreciable 


SAP-STAIN, MOLD, AND DECAY IN GREEN WOOD. 7 


extent. The starches, sugars, and oils stored in the sapwood and pith 
rays, together with the contained air and water, probably exert an 
influence upon the advancing hyphe and limit largely the growth of 

the fungus to the sapwood and the pith rays, where the sap-stain is 

mainly to be found. Practically no invasion of the heartwood takes 
place (Von Schrenk, 47, p. 19). (PI. I, fig. 3.) . 


“THE SAP-STAIN FUNGI. 


The relation of a fungus to the bluing of wood was first noted by 
_ Hartig (77, 78). He describes the organism which causes the so- 
called “bluing” of conifers, especially dead or dying pine that has 
been injured i= caterpillars, as Ceratostoma piliferum. He notes 
_ that it may also appear in damp firewood. According to Hartig, 
_ the brown mycelium very quickly penetrates the trunk through the 
medullary rays. He states that probably on account of the de- 
ficiency in moisture content the heartwood is avoided by the mycelium, 
whereas the sapwood often becomes quickly invaded and decomposed. 
Although described by Fries (73; see also Berkeley, 6), who placed 
_ it in the genus Sphaeria, the fungus was later transferred by Fiickel 
_ (14; see also Ellis and Everhart, /0) to the genus Ceratostoma. Sac- 
 cardo (39) still later divided the genus Ceratostoma and placed those 
_ species which possess colorless spores in a new genus, Ceratostomella. 
_ Winter (48) ,in a subsequent revision of the family included the fungus 
as Ceratostomella pilifera Fries under the new genus. It is now 
known as Ceratostomella pilifera (Fries) Winter (Engler and 
Prantl, 29). 
Figure 2 illustrates the fruiting bodies of this fungus. With the 
aid of a magnifying glass one may often see them clearly as stiff 
_ black hairs, approximately 1 millimeter (1/25th of an inch) in 
length,’ swollen at the bases, and forming, en masse, a dark hairy 
covering on the ends and tangential surfaces of stained sapwood. 
_ These growths when well developed are sometimes referred to by 
~ lumbermen as “ whiskers.” 
__. Many species of Ceratostomella have been listed by Saccardo (40). 
_ Though no reference is made to the fact, it is probable that a number 
_ of these stain wood. 
_ ‘The life histories of many species of Ceratostomella found on 
_ stained wood have been worked out by Von Schrenk (47), Hedgcock 
_ (29), and Rumbold (37) in this country and by Miinch (37) in 
_ Kurope. In connection with the study of several chromogenic fungi 
_ which discolor wood, Hedgecock developed in culture a conidial stage 
_ of Ceratostomella Sanectcatls resembling Cephalosporium. Miinch 
and Rumbold associated a Graphium stage with the development of 


- 5In some species the length may exceed 2 millimeters. 


eel 


=n ‘ 
i= 


- _ a 


8 BULLETIN 1037,:U. S. DEPARTMENT OF AGRICULTURE. 


Ceratostomella. During the extensive culture work of Hedgecock, — 
however, extending over a period of. four or five years and involving — 


Fie. 2.—Mycelium and fruiting bodies of “ blue-stain”’ fun- 
gus: 1, Tangential section of “ blue” wood; 2, cross sec- 
tion of “blue”? wood; 3, cross section of pith ray; 4, 
young fruiting body of the “ blue-stain’”’ fungus (Cerato- 
stomella pilifera) ; 5, mature fruiting bodies of the “ blue 
‘stain ’’ fungus; 6, two fruiting bodies of the “ blue-stain ” 
fungus; 7, two spore sacs with spores of the “ blue-stain ”’ 
fungus; 8, spores of the “ blue-stain” fungus; 9, top of 
beak of fruiting body of Ceratostomella pilifera just after . 
the discharge of the spore mass. (After Von Schrenk | 

(32), pl. 7.) 


a number of species of Ceratostomella from a variety of sources, no 
Graphium stage of this fungus was ever reported. 


Bu 


. 1037, U. S. Dept. of Agriculture. PLATE lI. 


EXAMPLES OF WooD INFECTION.—I. 


Fic. 1.—Radial section of bull pine, showing hyphe of the blue-stain fungus growing in the pith 
rays. Fic. 2.—Tangential section of the same, showing many small hyphe growing into 
the adjoining cells. Fic. 3.—Log of southern yellow pine containing sap-stain. Fie. 4.— 
Mycelium of mold growing between hard-maple boardsina kiln. Fic. 5.—Mold on the end of 
a sawed red-oak billet. Fic.6.—Manle billet containing sap-rot, a condition brought about 
through the agency of wood-destroying fungi. The surface has been polished to show more 
clearly the bleached and disorganized condition of the sapwood. (Figs. 1 and 2 are from Von 
Schrenk (41), pl. 8; fig. 4is from a photograph by H. D. Tiemann.) 


Bul. 1037, U. S. Dept. of Agriculture. PLATE II. 


EXAMPLES OF Woop INFECTION.—II. 


Fic. 1.—Artificially infected blocks of red oak and white oak in the tile chamber ready for the 
steaming experiments performed at the Madison laboratory. The large white areas of 
mycelium on the ends of the blocks in the upper four rows are wood-destroying fungi and 
probably developed as a result of infection in the log. Fic. 2.—Sawed felloes of oak (species 
not known). Note the abundant growth of mold which had developed in the material during 
shipment and while in storage. Photographed by H. D. Tiemann. 


ph, TS Bahl VOR i es 


SAP-STAIN, MOLD, AND DECAY IN GREEN WOOD. 9 


Hedgecock (19) identified the following species of Ceratostomella 
as responsible for the discolorations produced in certain woods: 
CO. pilifera (Fr.) Wint., in the sapwood of several species of pine (Pinus), 
fir (Abies), oak (Quercus), and ash (Fraxinus). 
C. schrenkiana n. sp., in short-leaf pine (Pinus echinata Mill.). 
C. echineila E. and E., in freshly cut heartwood and sapwood of beech (Fagus 
atropunicea (Marsh) Sudworth). 
C. capillifera n. sp., in wood of red gum (Liquidamber styracifiua L.). 
C. pluriannulata n. sp., in blue sapwood of red oak (Quercus rubra L.). 
C. minor t. sp., in Arizona pine (Pinus arizonica Eng.). 
C. exigua n. sp., in dead and dying trees of scrub pine (Pinus virginiana 
Mill.). 
C. moniliformis n. sp., in red gum (Liquidambar styracijfiua L.). 
Miinch (37) split up Ceratostomella pilifera Fries into a series 
of new species, as follows: 
1 Ceratostomella pini, the important blue-stain fungus of pine. 
2. The pilifera group, distinguished by the secondary fruiting bodies: 
(a) C. piceae,-with an associated Graphium stage, possibly Graphium 
penicillioides Corda, in species of pine and fir. 
(b) C. cana, with an associated but unclassified Graphium stage. This 
species he also found in pine wood. 
(c) C. coerulea, having no associated Graphium stage. 
_ With these species of Ceratostomella Minch includes two unrelated 
fungi, Yndoconidiophora coerulescens and Cladosporium sp., as 
causing discolorations in coniferous timber.® 
Von Schrenk (47), in his studies of the “ blue wood” in dead and 
dying stands of the western yellow pine (Pinus ponderosa Laws.), 
found that the spores of Ceratostomella blown about by wind or 
carried by insects are often deposited in the exposed ends left by the 
breaking of branches or in the holes made by the bark and wood 
boring beetles. There, under the favorable conditions which usually 
prevail, they germinate and readily produce in a short time many 
colorless, branching hyphe. The hyphe grow into the bark tissues, 
then into the cambium, and from there into the medullary rays. 


With age the hyphe take on a brown hue. 


According to Von Schrenk (47. pp. 18, 19), “one of the first effects 
seen after the hyphe have entered the medullary ray cells is the grad- 
ual solution of the walls separating the medullary ray cells from one 
another (fig. 2, 7, 2, 3). The walls which separate the ray cells 
from the neighboring wood cells may become very thin, as shown in 
the middle ray (fig. 2, 7), but they are rarely dissolved entirely. ‘The 
intermediate walls, on the other hand, entirely disappear. This 


SIn a recent. publication, C. J. Humphrey (23) describes a fungus, Lasiosphaeria 


 pezizula (B. and C.) Sacc., as the cause of a blue-black stain in certain hardwoods, par- 


ticularly beech and red gum. More detailed information concerning this fungus, as well 
as certain species of Ceratostomella, is given by E. E. Hubert (21). 


75579° —22 2 


10 BULLETIN 1037, U. S. DEPARTMENT OF AGRICULTURE. 


leaves a tube, with a cross section having the shape of the cross sec- 


tion of the ray, extending into the trunk from the bark. This tube ~ 


is sometimes filled entirely with a mass of brown hyphe, the larger 
number of which extend in the direction of the ray (PI. I, figs. 1 
and 2). From the ray cells some hyphe make their way into adja- 
cent wood cells (fig. 2, 2; Pl. I, figs. 1 and 2).7 They grow along 
these, both up and down (fig. 2, 7), giving off branches to other wood: 
cells. In this manner the whole wood body becomes penetrated by 
the brown hyphe in a very short time after the first infection. The 
number of hyphe in the wood cells proper, excluding the medullary 
ray cells and the cells of the wood parenchyma, is very small indeed. 
This is probably due to the fact that the fungus finds scant material 
upon which to live in the wood cells. The hyphe are apparently 
able to puncture the unlignified walls here and there, but they stop 
at that point. The writer was not able to demonstrate that the hypheze 
could attack the lignified walls. In other words, the ‘blue’ fungus 
is one which confines its attack to the food sub-tances contained in the 
storing cells of the trunk and to the slightly lignified walls of these 
storing cells.” According to the same authority (4/, p. 19), the resin 
ducts may be attacked in like manner (fig. 2, 3; Pl. I, fig. 2). 

In the case of sawed timber it is quite probable that the fungous — 
spores falling upon the surface of the sapwood find there the mois- 
ture and food material necessary for germination. Subsequently they 
give rise to a mass of mycelium, many of whose hyphe enter the 
wood through the exposed medullary or pith rays and then probably 
invade the surrounding tissue, as explained by Von Schrenk. 


SUSCEPTIBILITY OF VARIOUS WOODS TO SAP-STAIN FUNGI. 


The sapwoods of many kinds of timber are susceptible to sap-stain, 
though the degree of susceptibility varies considerably. Among the 
conifers southern yellow pine, western yellow pine, sugar pine, and 
the spruces seem to be readily stained and in the case of the broad- 
leaved trees, red gum, red oak, white oak, and hackberry seem to be 
particularly susceptible. 


Often there is a considerable difference between a species when i 


grown on the dry uplands and the same species when grown under 
the moist conditions characteristic of the lowlands (Von Schrenk and 


Spaulding, 44). This difference in woods of the same species may be : 


even more marked when grown in essentially different climates 
(Spaulding, 48). It seems to be the opinion of many lumbermen that 
timber grown in the South is more susceptible to fungous attacks — 
than timber grown in the North. If differences in susceptibility do — 


7K. E. Hubert (21) observed in the wood of scrub pine and northern white cedar 
hypbe of Ceratostomella sp., which had penetrated tracheids and wood fibers for a dis- — 
tance of several cells from the medullary rays. 


SAP-STAIN, MOLD, AND DECAY IN GREEN WOOD. i 


- exist in such woods it is difficult to state whether they are due to 
dissimilarities in mechanical structure, to the relative proportions of 
_ contained air and water, or to the variety and amounts of stored food — 
_ present in the wood parenchyma and medullary rays. It is probable 
that differences in environmental conditions, i. e., temperature and hu- 
_ midity as affecting the growth of the fungi, are important factors 
_ directly responsible (Roth, 35, p. 55-56). 


STRENGTH OF “ BLUED ” WOOD. 


Since the wood fibers are not appreciably impaired. by the growth 
of the blue-stain fungus, there should be no apparent loss in the 
_ strength of the invaded wood. Rudeloff (36) found that the compres- 
- sion strength of pine is not affected by the presence of bluing fungi. 
_ Tests on the stained wood of western yellow pine conducted at Wash- 
_ ington University, St. Louis, Mo. (Von ‘Schrenk, 47) and later at 
the Forest Products Laboratory, Madison, Wis. (Weiss, 56; Weiss 
and Barnum, 47) proved that there is practically no diminution in 
_ the end compression or cross-breaking strength and hardness of the 
stained as compared with the unstained wont In the case of heavily 
stained shortleaf pine, however, tested at the latter institution, there 
was found to be a slight ee in the strength, Ta se and 
7 ae as compared with unstained wood Hiking the same moisture 
- content. It may be safely stated that blued wood is practically as © 
strong as unstained wood. 


CAUSE OF THE COLOR IN “ BLUED” WOOD. 


The cause of the blue color in the wood has never been satisfac- 
 torily explained. R. Hartig (/7, p. 66) ascertained that it arises 
_ from the presence of the Sie fungous hyphe in the intercellular 
spaces. According to Von Schrenk (A, p. 18, 25-26), it appears in 
_ the wood when the colorless mycelium eaang. to take on the brown 
hue characteristic of the mature fungus. Microscopic examination 
of the wood fibers taken from the bined wood reveals no indication 
of a blue color. While extracts of the blue wood with alcohol, ether, 
~ benzol, chloroform, alkalis, and acids differ in appearance from 
those obtained from clear wood, yet no blue tinge is apparent. Von | 
—Schrenk (47, p. 26) suggests that possibly “there is some pigment — 
with a blue element in the ‘blue’ wood which is so faint that its de- 
tection in thin microscopic sections becomes almost impossible.” 
Hedgecock (79, p. 110-111) states that “ the brown color of the fungus 
apparently contains traces of a blue pigment whose color is trans- 
‘mitted by the wood cells of the pine more readily than the brown 
color.” Miinch (3/, p. 3) concludes that the color is due to the ar- 
rangement of the mycelial threads in the wood. He cites, as some- 


12 BULLETIN 1037, U. S. DEPARTMENT OF AGRICULTURE. re 


what similar examples, the blue color of thin milk, cigarette smoke, — 
and the clear sky, wherein very fine particles are held in suspension 
in a transparent medium. ; 


OTHER FUNGOUS ORGANISMS CAUSING SURFACE DISCOLORA- | 
TIONS IN GREEN TIMBER. 


In addition to the blue-stain fungi, there is another group, the _ 
molds, which commonly occur upon the freshly cut surfaces of green _ 
timber when stored under moist, warm, and stagnant conditions (PI. 

I, fig. 5; Pl. I, figs. 1 and 2). Molds are occasionally found growing 
vigorously upon timber in kilns (PI. I, fig. 4). This is especially 
noticeable when the atmosphere of the kiln is exceedingly moist or 
saturated and the temperature he 
from 90° to 110° F.8 or from 110° t 
130° F. (Tiemann, 5/7, p. 186-187). 

Hedgcock (79) showed that the 
blackening and browning so common 
in the green sapwood of pine (Pinus 
sp.), poplar (Populus sp.), tulip (Liri- 
odendron sp.), red gum (Liguidambar 
sp.), oak (Quercus sp.), maple (Acer 
sp.), and several other woods can — 
often be traced to species of Graph- 
ium. He cites: 

G. ambrosiigerum nt. sp., on Arizona pine 
: (Pinus arizonica Eng.). 

“7 : G. eumorphum Sacc., on wild hack rasp- 

ah ; berry (Rubus strigosus) and related species. 

a more ae mae : eae G atrovirens i Sp., “ red gum i Tigusd: 
ambar styraciflua L.). 


G. smaragdinum (A. and 8.) Sace., on red gum (Liquidambar styraciflua Eicy: 
G. rigidum (Pers.) Saec., on red oak (Quercus rubra L.). 
G 
G 


. aureum n. sp., on wh te pine (Pinus strobus L.). 

. album (Corda) Sace., on beech (Fagus atropunicea (Marsh) Sudworth). 

Graphium spp. are perhaps best known by the upright, cylindrical, 
occasionally branched fruiting bodies 1 to 3 millimeters in height 
(fig. 83). These are often brown to black in color and bear at the 
tips comparatively large and, in many cases, confluent globules com- 
posed of masses of spores embedded in a mucuslike substance. ‘These 
spore masses, though usually cream color, vary somewhat in hue, and 
in some species are tinged with gray, brown, green, yellow, or red. 
While these are the organs of fructification commonly observed, 
other types less conspicuous and bearing the so-called secondary 
conidia have been demonstrated in culture by Hedgecock (19). 


8 Information from the section of timber physics, Forest Products Laboratory, Macison, 
Wis. ; 


SAP-STAIN, MOLD, AND DECAY IN GREEN WOOD. 13 


_ Other fungi mentioned by Hedgecock (/9) as blackening wood are: 
Alternaria tenuis Nees., Stachybotrys alternans Bon., Aspergilus 
niger, Chaetomium sp., Stemonitis sp., Gliocladium sp., Hormoden- 
_ dron sp., Hormiscium sp., and Cladosporium sp. ‘The apparent dis- 
coloration in these cases is due either to the presence of colored 
hyphe in or upon the surface of the wood or to a luxuriant super- 
_ ficial growth of colored spore masses. In no case is it due to the 
secretion of any pigment which is absorbed by the wood. 
Hedgecock (19) names three other species—Penicillium aureum 
Corda, Penicilltum roseum, and a Fusarium sp. formerly included 
under Lusarium roseum—which, due to the secretion of soluble pig- 
ments, actually stain the wood red, purple, or yellow, according to 
the alkalinity or acidity of the medium. These stains are superficial, 
_ however, and readily dress off when the lumber is planed. Many 
_ other molds-grow readily upon green sapwood and give the timber 
a displeasing appearance, though they cause no deterioration in 
the strength of the wood. From the material collected by the writer 
and sent to the Madison laboratory there have been isolated over 40 
distinct species of fungi. With the exception of species of Ceratosto- 
_mella and Graphium, together with a species.of Fusarium which was 
identified by Dr. Mabel M. Brown, graduate student at the Uni- 
versity of Wisconsin, as /’. ek 2 GB i Be No this number consists of 
fungi popularly Eaten as molds. The determination of the molds 
_ was made by Dr. Charles Thom and Miss Margaret B. Church, of 
_ the Bureau of Chemistry, United States Department of Agriculture. 
_ They are listed below: 


Aspergillus flavus series. Penicillium asperulum or puberulum. 
Aspergillus niger. Penicillium brevicaule series. 
Aspergillus repens. Penicillium-commune. 
Aspergillus versicolor group. Penicillium divaricatum. 
Cephalothecium roseum. Penicillium lilacinum. 
Citromyces sp. Penicillium luteum. ; 
- Cladosporium sp. Penicillium purpurogenum. 

Clonostachys sp. Penicillium. roqueforti. 
Gliocladium. sp. Penicillium rugulosum. 
Haplographium sp. Penicillium solitum. 
Monilia sitophila. Syncephalastrum sp. 
Mucor sp. Trichoderma sp. 

. Oidium sp. 


_ The great variety of genera and species here noted contains many 
earth dwellers and indicates that the molds commonly found upon 
green timber, especially during storage and transit, are for the most 
part soil se whose spores have by accident fallen upon the 
_ moist surfaces of the sapwood and there found the conditions favor- 
able for development. 
It has generally been supposed that the growth of mold on wood 
: is confined mainly to the surface or, at the most, to the superficial 


14 BULLETIN 1037, U. S.. DEPARTMENT OF AGRICULTURE. 


layers, perhaps a few cells in thickness. H. Marshall Wate: (55), 
however, in connection with certain experiments upon spruce blocks — 
which had been artificially infected with Penicillium sp., notes that 
the examination of seetions from cultures 3 months old showed that 
the hyphe of this fungus had entered the starch-bearing cells in 
the medullary rays of the sapwood and had consumed the starch. 
The hyphe were observed deep in the wood extending from tracheid ° 
to tracheid through the bordered pits. Miss A. L. Smith (46) notes 
the presence of a dark-brown hyphomycete in decaying timber. This 
mycelium had invaded the woody tissue and had apparently brought 
about a partial destruction of the medullary rays (see also Rree 
man, 12). 

Diving a series of experiments by the writer, cultures were taken 
from various points within red-oak blocks 24 by 24 by 10 inches 
Jong which had been cut from green sapwood and then artificially 
infected with 15 different fungi including 13 of the common molds.” 

The results obtained seem to confirm Ward’s experiments, for posi- 
tive mold cultures were secured even from the center of these blocks. 
However, as far as known, the molds do not cause any serious disin- 
tegration of the cell walls in green timber and thus do not impair 
the strength of the wood to any appreciable extent. As in the case — 
of the blue-stain fungus, it is the stored food within the cells that is 
the object of attack. : 

The principal objection to the presence of mold lies in the dis- — 
coloration due to the masses of mycelium and the luxuriant clusters 
. of fruiting bodies which often develop upon green sapwood, and 
sometimes the heartwood, under conditions of high humidity and — 
temperature resulting from poor ventilation. However, these super- — 
ficial growths are readily removed during sanding or planing opera- 
tions. In many cases they can be ay brushed off. This is par- — 
ticularly true of material which has become surface dried. 

An inspection of a carload of moldy timber is quite likely to pro- 
duce an impression that is liable to react unfavorably upon the 
shipper. Moreover, the presence of much mold or sap-stain in — 
timber indicates the existence of conditions which are favorable to — 
the development of decay. Such material, then, should be viewed — 
with suspicion, but not of necessity with unfavorable discrimination. — 


“=e sey 


FACTORS WHICH FAVOR THE GROWTH OF SAP-STAIN AND MOLD > 
FUNGI. 


The development of fungi is dependent upon four factors—a sup- 
ply of air, containing the essential element oxygen; the requisite — 
® McBeth and Scales (30) list a considerable number of molds that are apparently able | 


to destroy cellulose, though they act differently toward different kinds of cellulose. 
10 See page 29 for the list of fungi used in this experiment. 


- 


-SAP-STAIN, MOLD, AND DECAY IN GREEN WOOD. 15 


amount of moisture; a temperature range within certain limits; and 
the necessary food substances. 

Air—Fungi require oxygen for their growth. This is supplied as 
one of the constitutents of ordinary air. Even under storage con- 
ditions the supply is ample. Stagnant air containing a considerable 
amount of moisture is favorable to the growth of fungi in the timber, 
in that it prevents the drying of the wood. Timber entirely sub- 
merged in water is practically immune from fungous attacks, since 
the supply of oxygen is cut off. 

_ Moisture—tThe extent of the growth of sap-stain and Bist fungi 
is largely dependent upon the amount of moisture present in the 
substratum. This moisture content in green timbers of different 
species as well as in the sapwood and heartwood of a particular 
species may vary considerably. Thus, according to Tiemann (45/, 
p. 106; 33, tables), the green sapwood of conifers may contain from 
100 to 150 per cent moisture, while the heartwood, probably being 
near its fiber saturation point, contains about 30 per cent. In the case 
of the hardwoods, both heartwood and sapwood may contain from 
- 60 to over 200 per cent moisture. Frequently, however, there is pres- 
ent a greater quantity of free water in the sapwood than in the heart- 
wood (Tiemann, 5/). In air-dried timber the amount of moisture 
may be reduced to anywhere from 8 to 18 per cent, according to the 


 elimate. In kiln-dried material it may be reduced to 3 to 15 per 
_ cent moisture, depending upon requirement and uses. This will 
explain why mold and sap-stain, so frequently found in green timber, 


are absent in thoroughly air-seasoned or kiln-dried stock. Air cur- 
- rents will often surface-dry the timber to an extent that will make 
it practically impossible for fungi to grow thereon. 

The relative quantities of water and air found in the wood, accord- 


- ing to Von Schrenk (43), are the most important factors in the con- 


trol of the rate of growth and spread of the sap-stain fungus. He 
cites Miinch’s experiments (32) on artificially inoculated pine blocks,” 


_ differing only in the relative amounts of contained water and air. 


These experiments seem to indicate that the growth of the fungus is 


- jnhibited when the normal winter water content of the wood is raised 


~ to an amount that will insure a consequent reduction in the volume of 


contained air to at least 15 per cent, based on the volume of the fresh 


wood. According to Miinch (32) an air content of 42 per cent, 
_ brought about through a reduction of the normal winter water con- 
_ tent of the wood, is the optimum for development of the fungus in 
_ the wood. Miinch (37, p. 59-62) states that the sap-stain fungus at- 


a Unless otherwise stated, all percentages of moisture content are based upon oven- 
ary weight. 

_ ©The blocks in this case were artificially inoculated with the conidia of Ceratosto- 
a mella coerulea. 


16 BULLETIN 1037, U. S. DEPARTMENT OF AGRICULTURE. 


tacks recently felled trees, but does not penetrate deeply, owing to the - | 
high water content of the wood. He also states that the mycelium of — 
the fungus readily penetrates throughout the sapwood of winter- — 
felled wood when the loss in water content amounts to 10 to 20 per — 
cent. Moreover, the growth in moist wood takes place for the most 
part in the older layers of the sapwood, or those in proximity to the 
heartwood. Finally, Miinch concludes that the sap-stain fungus is — 
capable of infecting the living tree, thus becoming parasitic, provided 
the fungous spores find entrance to the sapwood through injuries to — 
the bark, such as those produced by bark-boring beetles; and that con- 
ditions favorable for fungous growth, namely, a reduction in the 
water content and a corresponding increase in the air content of the 
sapwood, are brought about through disturbances in the root system 
of the tree. ; 

In this connection certain investigations by Snell (47) on the rela- 


tion of the amount of decay to the density of the wood should be men- — 


tioned. Five fungi which had been found to cause the rotting of 
structural timber in New England cotton mills were grown upon 
blocks of loblolly-pine sapwood and Sitka spruce. Several series of 
these blocks, each series containing a different percentage of moisture, 
were used in these experiments. The results obtained with loblolly 
pine agreed in the main with those of Miinch (32) upon Scotch pine, 
a wood of abeut the same density. In the case of Sitka spruce, a wood 
of considerably less density, however, it was found that the limits of 
moisture content favorable for fungous growth were raised. In other 
words, “the values representing the upper limits for decay will vary 
inversely with the density of the wood.” abies. ¢ 

Temperature.—It has been clearly demonstrated in a number of 
temperature tests ’* upon some of the molds derived from infected 
timber that these fungi grow readily between certain. limiting tem- 
peratures. Beyond these, they cease to show any signs of activity. 
The optimum temperatures are commonly those which obtain during 


the late spring and summer months in certain parts of the country, — 
particularly in the South, i. e., 80° to 85° F. It is probable, how- — 


ever, that each species has its own characteristic range. 
Food.—Sap-staining fungi and molds have been shown in cultures 
to live upon quite a variety of foods. Being devoid of chlorophyll ~ 


they can not, like the higher plants, manufacture their own food, but 


must depend upon that already available. The medullary rays and 
wood parenchyma of green sapwood often contain certain starches, 
sugars, and oils which represent the stored food of the tree. These 
are the substances upon which sap-staining fungi probably depend 
for their existence. 


13'These tests were conducted at the Forest Products Laboratory, Madison, by Mrs. 
Rose Harsch Lynwalter. 


SAP-STAIN, MOLD, AND DECAY IN GREEN WOOD. oe 


When supplied with the essentials necessary for growth, fungi 
develop rapidly and often reproduce abundantly. Deprived of any 
or all of these factors, however, the vegetative portion, 1. e.. mycelium, 
ceases to grow and eventually dies. In some cases, as, for instance, 
certain molds, the spores may retain their vitality for long periods 
_. under extremely unfavorable circumstances. When favorable con- 
_ ditions return, these spores soon germinate and often develop an 
abundant growth of mycelium within a few days. Fruiting bodies, 
sometimes bearing countless spores, may then make their appearance, 
and the life cycle is repeated. The ideal conditions for growth are 
often to be found in green timber containing a high percentage of 

sapwood when exposed to the stagnant atmosphere of the woods, 
poorly ventilated sheds, warehouses, and cars during warm, sultry, 
or rainy weather. Under such circumstances the sapwood may be- 

- come thoroughly infected within a few days. Sap-stain may thus 

appear soon after infection with spores or mycelium of the sap-stain 

fungi. Wood-rotting fungi may also get a good hold upon timber 
under such conditions, and symptoms of incipient decay later be- 

- come apparent (PI. I, fig. 6). 


DURABILITY OF STAINED OR MOLDED WOOD. 


Since the blue stain and mold fungi cause little or no dissolution of 


the wood fibers, they do not affect directly the durability of the 
_ timber. If properly piled and dried, stained or moldy wood stock 
_ free from decay should not deteriorate further from the action of 
_ the fungi. However, the conditions which favor the development 
of sap-stain, mold, and sap-rot are much the same, namely, the 
presence of spores or mycelium of the particular fungi capable of 
producing these defects in wood, a substratum containing the 
_ requisite food material, moisture, and a high relative humidity (75 
to 100 per cent), a temperature of 70° to 100° F., and a lack of circu- 
lation of the air, or stagnation, which retards or prevents the proper 
_ drying of the timber. There seems to exist among many lumbermen 
-a false notion that mold and sap-stain represent early stages in the 

_ development of sap-rot, or “ dote,” as it is commonly called. While 
_ the presence of an abundant growth of mold or sap-stain in green 
_ stock indicates conditions which are likely to favor the growth of 
_ rot, it is well known that the rot is caused by a distinct group of 
_ true wood-destroying fungi which develop independently. 
_ Molds in general develop rapidly. Hence, they may be often 
_ found growing profusely on green timber already infected ‘with rot- 
" producing fungi long before the latter have exhibited any notice- 
_ able evidence of their presence. It is possible, however, for wood 
Bdestroyers to infect and bring about the disintegration of wood ¥ which 
- contains no trace ef mold or any other organisms. 
Bx T5579° 


Fe. 


ae ; 
as >. 


18 BULLETIN 1037, U. S. DEPARTMENT OF AGRICULTURE. 


LOSSES DUE TO SAP-STAIN OR MOLD. 


INSANITARY PRACTICES IN THE HANDLING OF GREEN WOOD STOCK. 


As a result of investigations in the woods, inspections of many car- 
loads of green timber and dimension stock upon arrival at the mill, 
examinations of green and seasoned manufactured stock upon ar- 
rival at the vehicle factory, and talks with practical millmen and 
lumbermen, the writer is convinced that a considerable amount of 
the damage to vehicle stock, due to fungi, is brought about through 
the use of infected raw material. Many of the infections take place 
in the woods, as a result of insanitary practices in the handling of 
logs, bolts, and split billets. In many instances, during warm and 
humid weather logs and bolts have been allowed to lie in the woods 
for weeks. Under such conditions sap-stain is almost certain to fol- 
low. Moreover, the liability to attack by wood-destroying fungi} 1s 
greatly ie eeae 

Split billets, instead of being cross piled on dry foundations, a are 
sometimes ca Bees carelessly abaGe the stump and left until a con- 
venient time for hauling arrives. Under favorable circumstances it 
takes but a few days for certain fungi to gain a good hold on such 
stock, and unless later checked or destroyed by some process such as 
kiln drying, they may produce a permanent stain or decay in the 
sapwood. 20 

It is quite probable that a serious shortage of cars suitable for 
handling the logs, bolts, and billets may prevent at times the rapid 
movement of raw stock to the mills. This results in the aceumula- 
tion of material in the woods and railroad yards and contributes to 
conditions in many cases favorable to the development of the fung!. 
Frequently box cars are used where in normal times the more open 
and consequently better ventilated types of car would be employed. 

Failure to observe proper measures during storage, such as the 
use of dry foundations for logs and bolts, the cross piling or strip- 
ping of billets on dry foundations sufficiently high to give suitable 
ventilation from beneath, and the storage of stock in properly venti- 
lated sheds, has PAS conditions suitable for the development. 
of mold, sap-stain, and decay in such material. 

A ee millmen seem to have the mistaken idea that an abundant 
growth of mold on green stock serves to protect it from checking by 
preventing evaporation from the surface of the wood and actually 


absorbing, or possibly condensing, moisture from the surrounding — 


atmosphere and then transmitting it to the wood. The fungus de- 
rives its moisture from the wood, not the air. Its presence, however, 


often indicates a high humidity in the immediate vicinity, a condition 


which prevents the drying of the wood and thus favors the growth 
of fungi. It is quite probable that the phenomenon known as gutta- 


SAP-STAIN, MOLD, AND DECAY IN GREEN WOOD. 19 


w 


tion, i. e., the collection of minute drops of excreted water upon the 
fungous growth, is responsible for the misconception. 

In some instances split billets upon being unloaded from the cars 
are thrown in a pile beside the track, sometimes upon damp soil, there 
to remain for perhaps a month or until opportunity can be found for 
removal to storage sheds. Losses due to fungi are a natural conse- 
quence of such treatment. 

It has taken time for those unaccustomed to the handling of green 
stock to work out satisfactory methods which would provide proper 
ventilation of dimension, sawed, or turned stock during transit. 
Meantime, many shipments have been seriously damaged. Of the 
different forms of stock, the sawed billet, the rim strip, and plank 
have given the most trouble. Losses are not confined to such stock,. 
however, for turned spokes and hubs, unless properly safeguarded 
nda rue, are lable to stain and vie | 

- Sawed billets often arrive at the factory in a badly eines con- 
dition. It is probable that material containing fungous infections 
sometimes finds its way into their manufacture. The squared surfaces 
lend themselves to close piling and thus to the formation of masses 
wherein sufficient ventilation is impossible. Rimstripsalso frequently 
become badly stained while in transit, as a result of the same causes, 
together with the fact that some manufacturers require such stock 
to be close piled in closed box cars and even sprayed with water to 
prevent checking. It is unfortunate that the conditions necessary 
for the prevention of checking in green stock are as a general rule 
favorable to the growth of fungi, and vice versa. 


ECONOMIC IMPORTANCE. 


The presence of much sap-stain and even mold in timber is con- 
sidered by some lumbermen as a defect. Therefore, degrading of 
material thus affected, with consequent loss in miOnOtaey value, may 
result. Such arfaverable discrimination is due to the Klien: that 


stained or moldy material is not as sound as clear stock. In the case 


of molds, it is an easy matter to remove the surface blemish by the 
simple process of sanding or planing. . With sap-stain, however, the 
removal of the discoloration depends entirely upon the depth to which 


. the mycelium has penetrated. In some cases the stain may extend 


to the heartwood. It is evident that it can not under such circum- 
stances be removed by the processes referred to. 
The presence of much stain will prevent the use of timber for pur- 


poses where color, texture, and clearness of grain are of prime 
importance. Basket and box veneer, interior finish, flooring, and — 


_ furniture stock which are to have no protecting coat of paint must 
es be free from stain. Discrimination, however, should not be made 


20 BULLETIN 1037, U. S. DEPARTMENT OF AGRICULTURE. 


against sap-stained or moldy stock that is to be couered; provided 
there is no incipient decay associated with it. 

The reduction in the value of stained lumber sometimes amounts 
to $2 or more per 1,000 feet, board measure, and perhaps one-fourth 
of the annual mill cut of the United States is attacked. In one year 
it was estimated that the total losses from sap-stain amounted to be- 
tween 8 and 9 million dollars (Weiss, 56; Weiss and Barnum, 57; see 
also Pratt, 34). The amount in any locality, however, depends upon 
the eine. the season, and several other factors. 

Weather conditions have a marked influence upon the amount of- 
damage to freshly cut timber in the woods or to green stock in storage - 
and in transit. During warm and moist weather such stock will 
sometimes stain badly and in a short time, unless it is properly safe- 
guarded. This, of course, is due to the fact that the warm and humid 
conditions stimulate the development of the fungi. It follows, then, 
that the greater losses from sap-stain, sap-rot, or mold should be ex- 
pected during the warmer months, and especially during those 
months in which both high temperatures and high humidity nor- 
mally prevail. As a matter of fact, this is the case. In the months 
of April, May, June, July, and sometimes August and even Septem- 
ber, depending upon climatic conditions, the greatest damage occurs. 
In the South, owing to the prevailing high temperatures and relative — 
humidities, the losses are often extremely severe. The greatest losses 
occur in low-grade coniferous lumber, especially the southern pines, 
owing partly to the high percentage of sapwood and partly to the 
fact that the low-grade lumber is seldom kiln dried, but is stacked 
in the yard to air season. ‘Under such circumstances, unless unusual 
precautions are observed, it is very liable to the attacks of the sap- 
stain fungi. 

From replies to the questionnaires sent out by the wood-stock com- 
mittee to contractors and producers of wood stock regarding sap- 
stain and mold in vehicle stock and from the data derived from the 
personal investigations of the writer, it was learned that these losses 
are dependent largely upon the manner in which the stock is piled in 
‘the cars and sheds during transit or storage. The losses average less 
than 10 per cent, but may reach from 25 to 75 per cent. The writer 
was informed that because of such damage to green spokes during 
the summer of 1918, sometimes as many as 50 per cent in a carload 
lot were culled. When turned spokes were selling at $150 per 1,000 
feet b. m., the loss on a carload containing perhaps: 12,000 escort 
spokes, 24 by 24 by 27 inches, was evidently considerable, perhaps 
amounting to hundreds of dollars. One firm reported that it had 
knowledge of entire carloads being destroyed. In some instances 
cars had gone astray and had finally reached their proper destina- 


SAP-STAIN, MOLD, AND *DECAY IN GREEN WOOD. 21 


tion after one or two months on the road. Losses in those cases were 
often practically complete. Sixteen different firms reported that 
for the year 1917 their individual losses due to “heating in transit,” 
as staining is sometimes explained by lumbermen, varied from $100 
to $5,000. One company reported the losses as varying from $25,000 
- to over $75,000 in different years.** 


CONTROL MEASURES. 


A great many attempts have been made to devise measures for 
the control of sap-stain and mold in green timber. With the excep- 
tion of kiln drying, however, none of these has proved entirely satis- 
factory. When tried under circumstances unfavorable to the growth 
of fungi, some of these measures have met with considerable success, 
but when put to the test under conditions which stimulate fungous 
development, they have often failed. For the most part they have 
been prophylactic rather than curative in nature. However, it is 
believed that many of the following measures, although not entirely 
effective, will assist materially in reducing losses due to sap-stain, 
mold, and incipient decay in green stock. 


HANDLING IN THE WOODS. 


AUTUMN AND WINTER CUTTING. 


Many lumbermen (75) think that, where possible, timber should be 
cut in the autumn and winter. While this is probably true, the reason 
often given is incorrect. The statement is usually made that winter 
cutting is better because the “sap is down.” It has been shown by T. 
- Hartig (33, tables; Janka, 26) that during the spring when the growth 
is most active the treesometimes contains less water than in the winter.. 
It is probable that the changes in moisture content which do take place ~ 
are confined mainly to the sapwood. It is true that the movement of 
Sap is much more rapid at the time of active growth and that there 
are important chemical changes which take place therein during the 


: _ different seasons of the year. In the winter, insoluble starches and 


gums are stored -in the sapwood. During the spring these are 
changed to soluble sugars and are borne through the living tissues. 
The sapwood of summer-cut logs, therefore, contains soluble foods 
_ which render it extremely susceptible to attacks by fungi during the 
warm months when these organisms are most:active. Winter-cut logs, 
on the other hand, have an opportunity to season under conditions 
less favorable for fungots growth and by the time warm weather 


144 National Implement and Vehicle Association and other Vehicle and Vehicle Parts 


_ Manufacturers. Information Division of the Wagon and Vehicle Committee and the 


Wheel Manufacturers’ War Service Committee. Wood Stock Committee. Sap-stain and 


= mold in transit. Nat. Implement and Vehicle Assoc., etc., Bul. 30, 5 p. 1918. <A. B. 
_ _ Thielens, chairman. Typewritten. 


22 BULLETIN 1037, U. S. DEPARTMENT OF AGRICULTURE. 


arrives will have dried to a degree which will render them less sus-. ae 


ceptible to fungi (Roth, 35, p. 57). 


In the iia lands of the South, however, autumn ose, winter ac | 
cutting may not always be feasible owing to the wet and muddy 


ioudisinns then prevailing, which make hauling difficult, if not im- 
possible. 


Incidentally, leaf seasoning Cricieaaes $1), 1. e., girdling trees 


while in full leaf and then allowing them to remain, BS: for years 


or until the leaves have entirely shirjwelled up, with the idea that much 


of the free water in the sapwood will be drawn off by transpiration 
through the leaf surfaces and thus prevent sap-stain, does not seem to 
be practiced in the regions visited by the writer. Although this 
method is said to be common in the seasoning of teak in India and 
has been advocated by some as applicable to gum in this country, yet 
it does not. seem to meet. with general approval, because it exposes 
the timber to the ravages of insects and to fungi causing decay. 


RAPID HAULING. 


One of the precautionary measures to be observed, especially dur- 
ing the late spring and summer, is that of hauling timber immedi- 
ately after felling. Raw stock can not be gotten out of the woods 
and to the saw too rapidly. It is possible for fungous infections to 


take place at all times of the year on the exposed surfaces of freshly. 


cut timber. These develop more rapidly, however, during warm, 
humid weather, and especially under the conditions which obtain in 
the woods. 

STORAGE IN THE WOODS. 


If it is found necessary to allow logs and bolts to remain in the 
woods, they should be so separated that the ends are left several 
inches apart. If the sawed ends remain in contact, fungi are liable 
to develop between them. Some have recommended that logs that 
are to remain in the woods during the summer be painted on the 
exposed ends with creosote (Von Schrenk, 42). It has been con- 
sidered advantageous by some (Von Schrenk, 42; see also Hartig, 78) 
to remove the bark from logs that must of necessity be left in the 


woods for an extended period. Advocates of such treatment state 
that the peeled surfaces soon become air-dried and consequently 
provide insufficient moisture for the germination of any fungous 
spores that may fall thereon. In ‘eedees to keep such logs off the 


‘damp ground and thus assist in the air-drying process measures must 
be taken to provide some sort of temporary foundation free from 
stain, mold, or rot. 

When it hecdeas necessary to store split billets in the woods, they 


should be piled with only two billets in a course and should rest upon _ 


Pe eT Oe eee ee eee ee Ee 


os ae 


x 
f& 
- 


SAP-STAIN, MOLD, AND DECAY IN GREEN WOOD. 23 


a foundation located on dry ground and consisting, where possible, 


of billets of split heartwood free from rot. 


HANDLING RAW STOCK IN TRANSIT. 


TYPES OF CARS. 


In shipping green stock to be used in the manufacture of vehicles, 


etc., the following types of cars have been preferred: 


Flat carss.-_- pee ve Spee es loes figs 4). 

Gondolas or stock cars__--_----__ bolts (fig. 5). 

Stock or vegetable cars_____-____-. split billets or dimension stock. 
Pwonmniated box: cars. 2.23. lumber or dimension stock. 


Fic. 4.—Unloading logs from a flat car. This is; the type of car usually used for the 
Br : ' shipment of logs. ~ 


PROVISIONS FOR THE PROPER VENTILATION OF STOCK IN TRANSIT. 
Well-ventilated types of cars should be selected where possible, if 


staining and molding are to be prevented (figs. 4 to 10). Prepara- 
tory to use, these cars should be thoroughly swept free from 


rubbish, damp sawdust, lime, or manure. In the case of box cars, 
it is important that the roofs be carefully inspected to make sure 


that they are water-tight. If it becomes necessary to use box cars 
for the transportation of split billets during the late spring and 
summer months, it is suggested that the billets be ricked and that 
strips or occasional crossers of the same stock at intervals of 12 to 
16 inches be used to assist in the ventilation of the pile. Side doors 


‘should be open and both doorways boarded up, leaving at least 14- 
‘Inch spaces between the boards. If box cars are equipped with small 


24 BULLETIN 1037, U. S. DEPARTMENT OF AGRICULTURE. 


end doors of the ventilating type, these doors should be left open and 
the doorways cleated to prevent the stock from working out during 
transit. Lumber shipped in box cars must be stripped. 


HANDLING RAW STOCK IN THE YARDS. 
STORAGE OF LOGS AND BOLTS. _ 

When piling or cording logs and bolts in the yard for storage, it is 
important that they be kept off the ground by the use of clean skids 
or permanent foundations of seasoned fungus-free planks, stone, or 
cement. Such foundations should be placed on well-drained soil 
free from underbrush or weeds that might interfere with proper ven- 
tilation from beneath. 


Fig. 5.—Bolts loaded in a gondola car. Gondolas, stock, or vegetable cars are best 
adapted to the transportation of this type of raw stock. 


STORAGE OF BILLETS. 


Billets that are not turned at once should be stored upon dry 
foundations and in properly ventilated sheds (fig. 11). When suf- 
ficient storage space is available, the method of piling used by one 
of the large wheel manufacturers in the North, shown in figure 12, 


is recommended. 
STORAGE OF GREEN LUMBER. 


The methods of piling lumber are pretty well understood and need 
little explanation here (7).1° In general, it is well to select a location 


18 or information concerning this point, the reader is referred to Bulletin No. 552, 
United States Department of Agriculture (7), copies of which may be obtained from the 
Superintendent of Documents, Government Printing Office, Washington, D. C., at 10 cents 
per copy. 


* > «i 


% 


=: 


all courses and that 


stoclkx.16 


ES EI Tee 


SAP-STAIN, MOLD, AND DECAY IN GREEN WOOD. 25 


on well-drained soil free from weeds and one which will allow the 
prevailing winds to blow through the sides rather than upon the ends 
of the stacks. 

Care should be taken to provide suitable foundations consisting of 
metal or well-seasoned heart stock, preferably creosoted and resting 
upon piers of creosoted wood or, better, of stone, brick, concrete, or 
metal. All foundations should be sufficiently high to allow for 
ventilation vertically through the stacks. Moreover, there should be 
ample space between 
the stacks to permit 
a free circulation of 
the air around them. 
Finally, it is impor- 
tant that narrow 
strips, perhaps 1 inch 
wide and at least 1 
inch thick, of well- 
seasoned, kiln-dried, 
or chemically treated 
wood be used between 


they be carefully 
placed in. vertical 
alignment to prevent 
warping of the 


HANDLING AT THE MILL. 


EARLY MANUFACTURE. 


Logs, bolts, and 


split billets should be Fie. 6—Bolts piled in a box car. Note the débris on the 

ae ‘ floor of the car. Bolts are likely to suffer from fungous 
sawed into dimension attacks when shipped in box cars with the doors closed. 
stock or planks and 


manufactured as soon as possible. This will do much toward safe- 
guarding the material by reducing the time in storage. 


AIR SEASONING. 


Provided kilns are not available, the dimension stock should be 
seasoned from six months to a year or more, depending upon the 


%°The general sanitation of lumber yards and the proper methods to be observed in 
the piling of timber to prevent or reduce losses in storage due to fungi, together with a 
consideration of the mfore common rot-producing organisms, are clearly described by 
Humphrey (22), in Bulletin No. 510, United States Department of Agriculture. Copies 
may be obtained from the Superintendent of Documents, Government Printing Office, 
Washington, D. C., at 20 cents per copy. 


75579 ° —22—_4 


26 BULLETIN 1037, U. S. DEPARTMENT OF AGRICULTURE. i 


size and kind of material.17 When sufficiently dry, shipments in — 
closed box cars will suffer little or no loss from sap-stain or mold. 
In all cases where air seasoning is resorted to, unless great care is 
exercised in providing for ample circulation of air through the stock 
by such means as open piling, fungous and insect troubles are likely 
to develop. It is absolutely necessary to strip or cross pile the stock 
upon dry foundations. For purposes of stripping, kiln-dried or 
chemically treated strips 1 inch wide and at least 1 inch thick should 
be used between 
courses. All sheds 
for the storage of 
this material should 
be dry and well ven- 
tilated. 


KILN DRYING. 


By far the most 
effective and quickest 
method of treating 
green stock, as a pro- 
phylactic measure, to 
destroy fungi or in- 
sects and to reduce 
shipping weight, is 
to subject the ma- 
terial to proper kiln 
drying. When pro- 
ducers ‘are equipped 


Fig. 7.—Split billets piled in a box car. When occasional 
billets are used as crossers and the doors of the car are : 
cleated open this type of spoke stock suffers but little with, or have access 


while in transit. 


to, modern kilns op- 
erated on a scientific basis and, are so situated that stock can be 
moved rapidly, less concern need be given to fungous troubles. Kiln- 
dried spokes can be bundled or close piled in dry warehouses or in 
ordinary box cars and shipped without loss. ; 

Material kiln dried directly from the saw has been shown to be 
just as good as air-seasoned stock (Tiemann, 51, p. 300) and in many 
cases much better as far as strength, toughness, and freedom from 
defects are concerned. Moreover, the time necessary for seasoning 
can often be reduced from one year to three weeks or from three to 
five years to as many months. 


17 The reader is again referred to Department Bulletin No, 552 (7) for information con- 
cerning the seasoning of wood. 


VUE Ging 


SAP-STAIN, MOLD, AND DECAY IN GREEN WOOD. 27 


Kiln drying reduces shipping weight; makes the lumber fit for 
almost immediate use; eliminates or reduces losses due to insects,’* 
or to checking, rotting, staining, or molding; improves the quality 
of the lumber; reduces the amount of yard space; and saves the 
tying up of capital and carrying costs (Tiemann, 5/, p. 4, 5). 

It is possible that where several producers are located within a 
few miles of one another, a battery of modern dry kilns, operated 
according to the most approved methods (possibly on the community 
plan) might solve the problem of cost of installation and operation. 

In dry kilns, stripping or cross piling the stock and providing 
means to prevent stagnation of the confined air are absolutely neces- 
sary if the develop- 
ment of mold is to ke 
avoided. The water 
spray kiln devised at 
the Forests Products 
Laboratory represents 
one of the latest de- 
velopments in the tem- 
perature and humidity- 
controlled type of 
kiln.” 

_ During the first few 
weeks of kiln drying, 
when the humidity is 


Fig. 8.—Split billets loosely piled in the areaway between 
. the doors of a box car. The doorways are loosely 
high and the tempera- boarded up to allow for ventilation of the car and at 


the same time prevent the stock from working out 


| > S 
ture ranges from 80 while in transit. 


to 105° F., an abundant 

growth of white mycelium occasionally forms between the courses 
and interferes more or less with the circulation of the air in the kiln. 
This is due to the presence of mold fungi, and it usually indicates 
Stagnation in the kiln (Pl. I, fig. 4). Steaming for one hour at a 
temperature of 160° to 180° F. has been found effective in destroy- 
ing or at least checking the growth of this mold (Tiemann (45/), 
p. 187). 


18 Powder-post beetles, however, are said to cause considerable damage at times in 
Seasoned stock ; in fact, these beetles do not work in green stock. 
7%” A complete description of this kiln is given in Bulletin No. 509, United States Denart- 


‘ment of Agriculture (52), a copy of which may be procured from the Superintendent of 


Documents, Government Printing Office, Washington, D. C., for 5 cents. Further infor- 
mation concerning the design and installation of this kiln is given in Bulletin No. 894, 
United States Department of Agriculture (50), to be procured from the same source at 
10 cents a copy. 


28 BULLETIN 1037, U. S. DEPARTMENT OF AGRICULTURE. a 


STEAMING GREEN STOCK AS A CONTROL MEASURE. 


rd METHODS COMMERCIALLY EMPLOYED. 


Steaming certain kinds of stock (green gum lumber, birch hubs, 
spokes, and sawed felloes of red or white oak) is sometimes resorted 
to as a means of reducing shipping weight by hastening drying or 
to even up the color and reveal defects in the wood. 

In the steaming of green gum lumber a large steel tank, or pre- 
parator, is employed. The lumber loaded upon trucks is run into 
this preparator and steamed for perhaps 15 to 30 minutes at pres- 
sures of 20 to 80 pounds (figs. 13 and 14). Provided this lumber is 
then carefully open 
piled, it remains clean. 
When close piled or 
when exposed to ad- 
verse weather condi- 
tions, however, it may 
mold almost as readily 
as untreated green 
lumber. 

Hubs, sawed felloes, 
and turned spokes 
green from the saw are 
sometimes steamed at 


atmospheric — pressure. 


Fic. 9.—A box ear loaded with split billets upon its At one plant visited 
arrival at the spoke mill. The method of loosely ere ies 4 : 
boarding the doorway, as shown in figure 8, is prefer- %Yeen VIC ups were 


able in that there is less danger of the stock working gtgcked in large cement ~ 
out while in transit. When, however, the masses of = 

billets are held in position by supports, or when ver- boxes and subjected to 
tical boards are nailed a few inches back of the cleats, exhaust steam for 24 
this method may be used. Both provide for the venti- “ 
lation of the stock. to 36 hours, depending 


upon the size of the 
hub. At the end of that time the steam was shut off and the hubs 
were allowed to cool for perhaps 10 hours. The hubs were then 
carried to a ventilated warehouse and stacked, zigzag fashion, to 
provide for ample circulation of the air through the inside as well 
as around them. In this manner an even drying was secured. Two 
to three weeks was considered a sufficient length of time for the 
necessary air drying previous to shipping. During the warmer’ 
months, stock cars were used as means of transportation. 
The steaming of gum and birch is a comparatively simple process. 
But in the case of woods that check readily, such as oak, this treat- 
ment requires considerable care. 


SAP-STAIN, MOLD, AND DECAY IN GREEN WOOD. 29 


THE EXPERIMENTAL STEAMING OF RED-OAK AND WHITE-OAK BLOCKS AT THE LABORATORY OF 
FOREST PATHOLOGY, MADISON, WIS. 


During the spring of 1919 the writer performed several series of 
experiments at the Madison laboratory to determine the efficiency of 
steam at atmospheric pressure in destroying mold and sap-stain fungi 
in artificially infected red or white oak blocks 24 by 24 by 10 inches. 
Incidentally the rate of drying and the amount of checking were 
noted in connection 
with the steaming. 

The blocks were 
sawed from the sap- 
wood of summer-cut 
logs, weighed, and 
then sprayed with a 
water suspension of 
spores taken from 
cultures of mold 
fungi originally de- 
rived from infected 
material sent in by 
the writer. A_ list 
of the fungi used in 

these experiments 
follows: 

Aspergillus flavus. 
Aspergillus niger. 
Cephalothecium roseum. 
Ceratostomella sp. 
Citromyces sp. 
Graphium sp. 

Monilia sitophila. 
Mucor sp. 

Penicillium asperulum. 


Penicillium divaricatum. 


Penicillium luteum. 
Peniciilium pinophilum. Fie. 10.—Square billets close piled in a box car. This type 
of raw stock suffers considerably when piled in the 
manner shown here. Stripping or cross piling while in 
Syncephalastrum sp. transit or storage is essential if losses from fungi are 
Trichoderma sp. to be avoided. 


Penicillium rugulosum. 


The sprayed blocks were then placed in a tile chamber, which 
served as an incubator. After several weeks in this chamber, where 
an average relative humidity of 95 per cent and an average tempera- 
ture of 70° F. prevailed, the blocks became well infected and de- 
veloped countless numbers of the fruiting bodies peculiar to the fungi 
mentioned above (PI. IT, fig. 1). 


30 BULLETIN 1037, U. S. DEPARTMENT OF AGRICULTURE. 


A steam box was constructed of cypress, equipped with thermome- 
ters, dew-point apparatus, and manometer and connected with the 
main which supplies steam to the laboratory greenhouse (figs. 15 and 
16). By means of suitable reducing valves in the connecting pipes 
it was possible to control the steam pressure in the box; hence, the 
exact conditions to 
which the blocks 
were subjected could 
be readily determ- 
ined. Steam at at- 
mospheric pressure 
only was used. 

Previous to steam- 
ing, the blocks were 
again weighed. 
They were then 
close piled or strip- 
ped in groups of 25 
in the steam box and 
steamed for differ- 
ent lengths of time. 
At the end of the 
steaming period, 
some of the lots were 
allowed to cool for a 
certain time and then 
reweighed. Others 
were weighed imme- 
diately. Nearly all 
were put in a small 
ventilated box in the 


open and allowed to 


Fig, 11.—Stacking sawed billets in an open shed. It will air-dry for several 
be observed that the billets at the extreme right are 
cross piled, while those in the center are close piled. weeks. Some, how- 
The former method of piling insures a better ventila- ever, were placed in 
tion of the stack, provided intervals of at least 1 inch 
are left between the adjacent billets of a course. In a closed shed for 
the case of the cross-piled billets shown here this pro- foyr weeks, and still 
vision was not made. 


others were taken 
from the steam box, weighed, and placed directly in the tile chamber. 
Some lots were stripped; others were close piled. An interval of at 
least 8 inches was maintained between adjacent piles. 

After the preliminary seasoning mentioned above, a number of the 
blocks were returned to the tile chamber for incubation. This was 
done for the purpose of subjecting the blocks to the conditions exist- 
ing in box cars and poorly ventilated warehouses during warm and 


/ 


/ 


SAP-STAIN, MOLD, AND DECAY IN GREEN WOOD. 81 


sultry weather. The tile chamber, when given a preliminary treat- 
ment, which consisted of intermittent steaming for three successive 
days to reduce the amount of viable fungous growth therein, pro- 
vided these conditions admirably. In this chamber the temperature 
was maintained at an average of 85° F., while the relative humidity 
varied from 70 to 95 per cent. At the end of four weeks in the tile 
chamber the blocks were removed and their condition with respect 
to molding noted. 

The following observations were made from several series of exper- 
iments : 


The amount of drying which took place in the steam box was comparatively 
slight. This seemed to depend, however, upon the relative moisture content of the 
wood previous to steam- 
ing. Green blocks usu- 
ally lost, while partly 
seasoned blocks often 
gained in weight. 

‘ Beyond a certain 
length of time, dependent 
upon the moisture con- 
tent of the wood and 
the surface area of the 
blocks in relation to vol- 
ume, there seemed to be 
little gained, in so far as 
the reduction in weight 
was concerned, by con- 
tinued steaming. Six or 
hine hours’ steaming 
seemed to be no more 


(RAAGE OVALS 

2 ae aad 
Lan oS Hin of 
Wits, WML. STIs ad 


Fic. 12.—Diagram illustrating one method of stacking 
green split billets. This method is used by one of the 
large wheel factories of the North. When ample storage 


efficient than three hours space in well-ventilated sheds is available, this method 


in the case of the 24 by is recommended. 
24 by 10 inch blocks. 

Steamed blocks subsequently dried more rapidly than those that were simply 
air-dried. 

Open piling or stripping in the steam box was preferable, in that it per- 
mitted a better circulation of the steam in the box and bag insured a more 
uniform treatment of the blocks. 

The amount of checking varied in the several lots when steamed under the 
Same conditions. This may have been due to the fact that the blocks differed 
considerably in the relative proportion of sapwood and heartwood present. © 

The greatest amount of checking occurred in those lots that were subjected 
to rapid cooling and surface drying by exposure to air currents from open doors 
and ventilators. Blocks allowed to cool in the steam box with doors closed 
seemed to suffer least-in this regard. Slow cooling was, in some cases, brought 
about by opening a small hatch in the roof of the steam box at the conclusion 
of the steaming period. 

The total amount of checking which had taken place in the steamed blocks, 
both during the steaming process and the subsequent period of air seasoning, 


% extending over four months, exceeded but little that noted in those blocks which 


had been simply air seasoned for the same length of time. 
Steaming seemed to be effective in killing the fungi in the infected blocks 


a when employed for a period of three hours. Cultures taken from various points 


32 BULLETIN 1037, U. S. DEPARTMENT OF AGRICULTURE. 


in or upon the blocks by means of a sterile scalpel and needle gave no growth, 
while cultures taken from check blocks which had not been steamed gave positive 
results in every case. 

Steamed material, unless open piled under conditions which insured an ample 
supply of circulating air, molded almost as readily as green stock. 

Steamed blocks that were given a month’s air drying subsequent to steaming 
and previous to storage under the extreme conditions that prevailed in the tile 
chamber showed a little more resistance to the invasion of fungi than those 
blocks that were placed in the tile chamber immediately after steaming. 


It is quite probable that the steam treatment of wood stock, fol- 


lowed immediately by prolonged submersion of the material in some 
of the antiseptic solutions to be described later, might prove to be a 


Fic. 13.—Boards of red gum loaded on a truck and ready to be rolled into-the prepa- 
rator (shown in fig. 14). 


fairly effective method for the control of fungi in infected stock. 
This treatment might be applied to special classes of wood stock 
where the margin of profit would justify the extra cost. 


THE CHEMICAL TREATMENT OF GREEN WOOD STOCK. 


Many attempts have been made to find some chemical compound 
or mixture that, when applied as a dip, will control sap-stain and 
mold in green timber. A great many substances have been tried, but 
none have proved entirely satisfactory. Under conditions not par- 


ticularly favorable to the growth of fungi, several have met with 


considerable success. On the other hand, if the conditions were 
stimulating to fungous growth, the same substances often failed. 
Some treatments depend for their efficiency upon. the neutralization 
of the acids in the wood and, at the same time, the establishment of 


Se pee ee ge ne Te Se Re aes ane eee 


7% 


Adie oe 
ae eet 


SAP-STAIN, MOLD, AND DECAY IN GREEN WOOD. 33 


alkaline conditions. To this group belong sodium carbonate, sodium 
bicarbonate, sodium hydroxid, lime, and borax. Others are intended 
to poison the food of the fungi, and comprise such compounds and 
mixtures aS mercuric chlorid, copper sulphate, sodium fluorid, creo- 
sote, and many other substances. 

Toxicity tests (Humphrey and Fleming, 24)? conducted at the 
Madison laboratory upon a few molds commonly occurring upon 
infected timber, as well as upon several wood-destroying fungi, have 
clearly demonstrated that when the entire culture medium is perme- 
ated with these and many other preservatives, often in very small 
amounts, the growth of the fungus can be readily inhibited. Hence, 


Fic. 14.—Preparator used for the commercial steaming of red-gum lumber at one of 
the mills in Arkansas. 


if wood be thoroughly impregnated with a solution of one of these 
common preservatives it will be protected from decay as well as from 
Sap-stain and mold. 

This is quite possible in the case of thoroughly seasoned timber 
impregnated with preservatives by subjection to high pressure in 
closed retorts. The penetration of green timber by cold solutions 
of salts in an open tank or by the brush treatment, however, is ex- 
tremely slight.2"_ Tests made by the writer for the presence of cop- 
per in the interior of 3 by 3 by 14 inch blocks sawed from the green 


2 Information also obtained from unpublished reports of toxicity experiments per- 
formed by Miss C. Audrey Richards at the Laboratory of Forest Pathology, Madison, Wis. 

72 Tor a description of the pressure, open-tank, and brush treatments, the reader is re- 
ferred to Forest Service Bulletin No. 78 (45) and to Farmers’ Bulletin 744 (25), U. S. 
Department of Agriculture. 


34 BULLETIN 1037, U. S. DEPARTMENT OF AGRICULTURE. 


sapwood of red oak and then dipped for 10 seconds in solutions of 
copper nitrate and copper sulphate at ordinary temperature showed 
that these solutions had penetrated the ends of the blocks for a dis- 
tance less than 5. millimeters (one-fifth of an inch) and scarcely a 
measurable amount in the case of the tangential or radial surfaces. 
It is evident, then, that whatever value there is in the use of cold 
dipping solutions lies entirely in the superficial coating of the pre- 
servative left upon the wood. Provided this is not brushed off or 
washed off by rain, it may inhibit or prevent the germination of 
fungous spores which happen to fall upon such surfaces. Hot solu- 


Fig. 15.—Steam box of cypress used in the experimental steaming of red-oak and 
white-oak blocks at the Madison laboratory. 


tions, in that they tend to prevent the collection of bubbles of air 


upon the surface of the wood, probably give a more uniform distribu- 
tion of the preservative over the dipped material. As far as pene- 
tration is concerned, however, it is doubtful whether the hot solu- 
tions, as ordinarily employed, possess any very great advantages. A 
slightly increased penetration may be secured by first subjecting the 
stock to a thorough steaming or by heating it for some time in a hot 
solution of the preservatives, as in the open-tank process. The air 
within the cavities of the wood is thereby expanded, and some es- 
capes. Provided the steamed or hot wood is at once transferred to 
a cold solution of the preservative and there allowed to remain till 


SAP-STAIN, MOLD, AND DECAY IN GREEN WOOD. 35 


cool, an amount, approximately equal to the original volume of the 
escaped air, will be forced into the wood. ‘This is a slow process, 
however, and therefore somewhat expensive. 

The rate of evaporation of the liquid, in the case of hot solutions, 
is much greater than in cold solutions ; hence, it becomes necessary to 
take frequent hydrometer readings of the bath and to make the 
proper adjustments in the relative proportions of the solvent and dis- 
solved substances in order to maintain a uniform concentration. 

Dipping may be of some value when applied to stock free from 


fungi. In those cases 
where the fungi are 
already in the tim- 
ber, however, it is 
doubtful whether 
very much good can 
result from chemical 
dips unless the ma- 
terial be subjected 
first to a relatively 
high temperature 
and for a length of 
time sufficient to de- 
stroy these organ- 
isms. 

The salts used in 
the chemical treat- 
ment of lumber are 
likely to vary con- 
siderably in strength 
and purity. It is 
probable that the 
lack of uniformity 


in the results ob- Fig. 16.—Details of the interior of the steam box used in 


tained by different the experimental steaming of red-oak and white-oak 
blocks at the Madison laboratory. 


investigators when 
employing nominally the same compounds may be traced partly to 
this cause. A few of the preservatives commonly used are de- 


scribed here. 
SODIUM CARBONATE AND SODIUM BICARBONATE. 


The substances which have been most frequently employed to pre- 
vent sap-stain in lumber are sodium carbonate (commonly in the form 
of soda ash) and sodium bicarbonate (baking soda). Solutions of 
these salts are applied either hot or cold by dipping in an open tank. 
On southern yellow pine, when used in concentrations of 4 to 5 per 
cent sodium carbonate and 5 to 6 per cent sodium bicarbonate, these 


36 BULLETIN 1037, U. S. DEPARTMENT OF AGRICULTURE. 


substances have given more or less satisfactory results (Weiss and 
Barnum, 47). In wet weather, however, it has been found necessary 
practically to double the strength of the solutions. Moreover, both 
sodium carbonate and sodium ‘bicarbonate cause a yellow to brown 
discoloration of the wood. Lumber treated with these preservatives 
must be open piled or it may mold and stain badly during warm, — 
humid weather. . 

A good grade of sodium carbonate in the form of soda ash should | 
contain 584 per cent alkali, while the amount present in sodium bi- © 
carbonate (baking soda) is about 37 per cent. Solutions of the latter — 
are more or less decomposed at temperatures above 158° F., giving off | 
carbon dioxid. In a series of laboratory experiments followed by © 
practical field tests on southern yellow pine and red gum, Rumbold 
(37) found that the blue-stain fungus is sensitive to alkalis but not 
to acids, that an 8 per cent solution of sodium carbonate is as effec- _ 
tive as an 11 per cent solution of sodium bicarbonate, and that the — 
amount necessary to prevent growth varies with the. substratum. — 
Freshly cut sapwood of southern yellow pine or red gum required 8 ~ 
per cent sodium carbonate and 10 per cent sodium bicarbonate solu- — 
tions under conditions which were especially favorable for the growth — 
of the blue-stain fungus. In dry weather a weak solution of the ~ 
alkali (a 5 per cent solution of sodium carbonate and a 4 per cent — 
solution of the bicarbonate) kept the yellow pine boards free from — 
stain. It was also observed that the spores of the blue-stain fungus 
are more resistant than the mycelium. These experiments seem to 
show that sodium carbonate and sodium bicarbonate possess some — 
value as a preventive against sap-stain but that the success attending — 
the treatment is largely dependent upon weather conditions. 


SODIUM FLUORID, SODIUM BIFLUORID, AMMONIUM FLUORID. 


Sodium fluorid, which has proved to be very toxic to wood-destroy- — 
ing fungi (Teesdale, 49), has also been tested to determine its 
toxic properties in connection with the blue-stain fungus. Represen- ~ 
tatives 2 of the Forest Products Laboratory, working independently — 
and in cooperation with certain lumber mills located in Mississippi ~ 
and Louisiana, found that both sodium fluorid and sodium bifluorid 
were effective against sap-stain. The fluorids have an advantage 
over sodium carbonate and sodium bicarbonate in that they do not 
discolor the timber. One of these investigators, in a comparative 
series of experiments with a number of preservatives, including 2} — 
per cent sodium fluorid, 23 per cent sodium bifluorid, and 24 per cent 
ammonium fluorid, Scand that in the concentrations montiegee these 
salts were fairly eieative against sap-stain. The ammonium fluorid, 


22 Unpublished reports by Pettigrew and Knowlton in the files of the Forest Products 
Laboratory, Madison, Wis. —_ 


SAP-STAIN, MOLD, AND DECAY IN GREEN WOOD. 37 


- in addition, seemed to be of some value in controlling mold. How- 
ever, both of these series of experiments were performed during hot 
and dry weather—conditions unfavorable to fungous growth; hence, 
_ it is impossible to draw satisfactory conclusions from the results. 

While the fluorids may be effective in controlling decay and, to a 

_ certain extent, stain-producing organisms, they can not be depended 

- upon to prevent molding. | 


MERCURIC CHLORID. 


Probably the best antiseptic to prevent sap-stain and mold in green 
_ wood stock is mercuric chlorid. When used on coniferous woods and 
_ on many of the hardwoods in concentrations of 0.1 per cent to 1 per 
cent, it has been found to be exceedingly efficient. The addition of 
«60.1 e 1 per cent hydrochloric acid is said to increase its stability. 
-Mercuric chlorid, however, is extremely poisonous when taken in- 
- ternally. Many individuals show a marked susceptibility to the 
_ poison even when applied externally. Moreover, the solutions of 
_ mercuric chlorid are corrosive to iron, zinc, and many other metals 
~ commonly employed in dipping vats. For these reasons it can not be 
~ recommended for general use. 


_ SOME RESULTS OBTAINED FROM THE USE OF ANTISEPTICS BY VARIOUS INVESTIGATORS. 


It is probable that the efficiency of a given antiseptic varies consid- 
erably when applied to woods of different species and at various 
_ stages of air seasoning. As stated before, the results are likewise de- 
_ pendent upon climatic conditions. On open-piled boards of shortleaf 
F pine in Missouri, Von Schrenk, Bessey, and Spaulding found that 5 
per cent sodium bicarbonate or one-twentieth per cent mercuric 
- chlorid gave good results (Hedgcock, 20). On open-piled white pine 
in Wisconsin, the first two investigators found that the solutions giv- 
ing the best results were 5 per cent borax and 2.5 per cent sodium bi- 
_earbonate, while on boards of Norway pine in open piles 5 per cent 
borax, one-twentieth of 1 per cent mercuric chlorid, and 2.5 per cent 
_ sodium bicarbonate were most effective (Hedgcock, 20). As the re- 
sult of experiments on longleaf pine boards in open piles at Bogalusa, 
La., Weiss and Barnum (56, 57) concluded that the most effective 
antiseptics for the control of sap-stain, in that wood at least, are mer- 
euric chlorid in concentrations of 0.1 to 1 per cent.and oahu bicar- 
pbonate | in strengths varying from 5 to 10 per cent. In these experi- 
ments 5 per cent borax gave poor results. 

_ Hedgcock (20), in connection with certain experiments at Balti- 
‘I ‘more, Md., on the prevention of mold and stain in veneer baskets 
made om poplar, sycamore, beech, gum, and maple, found that the 
Froct effective solutions were 10 per cent sodium carbonate, 6.5 and 
‘10 per cent sodium bicarbonate, 2.5 per cent sodium bicarbonate plus 


> 
| 


38 BULLETIN 1037, U. S. DEPARTMENT OF AGRICULTURE. 


0.66 per cent borax and boric acid, 0.20 per cent sulphur plus 0.20 
per cent lime, 0.10 per cent mercuric chlorid plus 0.20 per cent 
hydrochloric acid, 10 per cent potassium (alum), and 0.33 per cent 
phenol salicylate. He concludes that of these substances, 5 to 10 per 
cent sodium bicarbonate is the safest and best to use. 


In nearly all the cases cited the antiseptics proved to be of some 


value in preventing the growths of the sap-stain fungus. Molds, 
however, are extremely resistant to chemical treatment and con- 
sequently are difficult to control. To quote from Lafar (28): 


' 


“Whether the waterproof character of some cell membranes, e. g., 
the conidia of Penicillium and Aspergillus, should be attributed to 


Fic. 17.—Barrels and steam-coil connections as used in the experimental dipping of 
red-cak spokes at one of the large spoke mills in the South. 


the deposition of excreted fatty or waxy substances must be left 
undetermined. Biologically this phenomenon is important, since it 
prevents the penetration of toxic substances from the aqueous 
medium and thereby also opposes the attempts of the mycologist to 
kill such fungi by means of aqueous toxic solutions.” Since, as has 
been stated repeatedly, molds develop largely on the surface of the 
timber and are sufficiently removed during the several finishing proc- 
esses to which the timber is sooner or later subjected, their presence 
in most cases should occasion but little concern in connection with 
vehicle stock. 
EXPERIMENTAL DIPPING OF RED-OAK SPOKES. 


DIPPING. 


In July, 1918, several series of experiments were performed by 


the writer in cooperation with one of the large spoke mills of the — 


" 


ee ee ee ek we 


—— a 


‘ox 


eT ae See ee ee 


Acie CD ee 


ES eae ey ee er es, OEY eee eee ee 


SAP-STAIN, MOLD, AND DECAY IN GREEN WOOD. 39 


South. It was desired to test in a more practical way some of the 
antiseptics that had been used on a small scale during prelimi- 
nary experiments at the Madison laboratory. In these experi- 


; ments first-grade escort spokes 24 by 24 by 27 inches long of red oak 


were used. They were selected mainly for two reasons: First, red 
oak in a green condition was the wood, of all those used at this par- 
ticular mill, which seemed to be the most liable to mold and sap- 
stain; second, the escort spoke was convenient to handle in connec- 
tion with the dipping apparatus employed. 

All spokes were taken directly from the warehouse after turning 
and grading. It was noted that 80 to 90 per cent of them contained 
sapwood varying in amount from 5 to 100 per cent. 

In leu of dipping tanks it was decided to use whisky barrels of 
50-gallon capacity. Three of these were placed on a platform in 
the mill yard beside the tracks upon which the trucks were operated. 
One barrel was equipped with a steam coil of bent 4-inch iron pipe 
provided with shut-off valves (fig. 17). This coil, when connected 
- with the main steam boiler, supplied the necessary heat for main- 
_ taining the temperature of the dipping solutions. A piece of cor- 
 rugated, galvanized-iron plate, approximately 2 by 6 feet. when 
supported in a slanting position with the lower end resting upon the 
_ top of the barrel, served as a drain board. Iron tongs similar to 
_ those used by blacksmiths, hydrometers, thermometers, and a gallon 
_ measure completed the list of essential apparatus. 

The following antiseptics were applied 1 in the form of solutions or 
ina dry state: 

A) Barrett’s grade 1 liquid creosote, 10 per cent by volume. 

Perfection kerosene oil, ee per cent by volume. 
Temperature, 80° to 90° F 
(6) Barrett’s grade 1 liquid es 10 per cent by volume. 
Perfection kerosene oil, 90 per cent by volume. 
Temperature, 150° to 155° F. 
(c) Powdered borax, 5 per cent by weight. 
Water, 95 per cent by weight. 
Temperature, 80° to 90° F 
(d) Mercurie chlorid (C. P.), 1 per cent by weight. 
4 Hydrochloric acid (commercial), 1 per cent by weight. 
= Water, 98 per cent by weight. 
= -*' Temperature, 80° to 90° F 
(e) Dry salt (finely grained). 
(f) Dry quicklime (finely powdered). 
_ The spokes were conveyed to the dipping barrels on trucks. There 
_ they were grasped by means of the iron tongs, immersed from 5 to 
- 10 seconds in the bath, and then placed on the corrugated-iron drain 
- board (fig. 18). When practically all- of the excess liquid had 
_ drained off they were again grasped with the tongs, loaded upon 
_ another truck, and wheeled to the north end of one of the open sheds 


40 BULLETIN 1037, U. S. DEPARTMENT OF AGRICULTURE. 


in the yard. There they were unloaded, close piled, and allowed to 
remain until ready for shipment. 

During the dipping operation it was observed that in some cases 
as many as 10 to 15 per cent of the untreated spokes in a given truck 
load showed the presence of sap-stain. In one lot the number show- 
ing sap-stain and mold was estimated at 50 per cent. Other lots. 
were practically free from fungi. During the experimental work 
the weather was for the most part hot and dry. Following one or 
two light showers the amount of mold on untreated material showed 
a marked gain. 

The methods of dipping were similar for all baths except in the 
case of the hot creosote. Here, the steam coil was employed and a 


‘ 
eer eee | weed. 


°s 
x 
, 


Fig. 18.—the experimental dipping of red-oak spokes green from the lathe. 


temperature of 150° to 155° F. maintained. One barrel served for 
both cold and hot creosote. The borax was dissolved by aid of the 
steam coil in the second barrel. A third barrel was necessary for 
the mercuric-chlorid dip. Thermometer and hydrometer readings 
were taken at frequent intervals, and whenever necessary correc- 
tions were made to maintain a constant temperature and concentra- 
tion in the bath. 

Incidentally, it was noticed that ambrosia beetles were very 
quickly killed by the creosote dip, a point of importance to consider 
in controlling insect pests which at times, especially during warm — 
and damp weather, are said to cause considerable losses in piled 
lumber.” (Weiss, 56, p. 18-20.) 


*s A certain species of beetle, Dendroctonus ponderosae Hopk., has been mentioned by 


Von Schrenk (41) as being partly responsible for the dissemination of the spores of the 
blue-stain fungus. 


SAP-STAIN, MOLD, AND DECAY IN GREEN WOOD. 41 


Both cold and hot solutions of creosote may cause considerable 
irritation, and in some cases blistering, when brought in contact with 
the skin. By proper use of the tongs, however, this trouble was 
avoided. Rubber gloves were worn during the dipping of spokes 
in the solutions of mercuric chlorid, since that salt, as already 
stated, is a deadly poison when taken internally and is sometimes 
absorbed through the skin when solutions are handled continuously. 

Many metals, such as iron and zinc, possess the common property 
of pipiudétinc metallic mercury from the solutions of its salts. 
For this reason the iron tongs and other metallic objects could not 
be used in connection with the mercuric-chlorid dip. 

The spokes that were treated with salt or lime were placed, a few 
at a time, in wooden boxes containing the respective substances in a 
finely powdered state and were rolled to distribute the chemicals 
over them as evenly as possible. The excess was shaken off. They 
were then close piled in one section of the warehouse. After 24 


hours the lime coating showed a marked tendency to absorb moisture 


and cake. Moreover, it turned the wood dark. For this reason the 
liming was discontinued after 300 spokes had been treated. The 
salted spokes soon became exceedingly moist, due to the hygroscopic 
nature of the salt. The antiseptics used and the number of spokes 
treated in the different lots follow: 


(a) 10 per cent creosote in kerosene, cold_______-_-_-- se 5, 100 
(6) 10 per cent creosote in kerosene, hot_________________. 5, 100 
ie aie pen cent; borax in »watef_~2—b.-2-254-4. 44. --L.i-_. 1, 013 
(d) 1 per cent mercuric chlorid plus 1 per cent hydro- 
Ny AA a pe a Sa 1, 000 
iS ree ee ee Rg ee See 1, 032 
Merenrmrcuiime. F4 2hY! ies Ji sei Oe su 300 


The first lot went forward in a box car loaded to capacity with 
5,000 cold-creosoted spokes, 5,000 that had been hot creosoted, 800 
oaks that had been dipped in mercuric chlorid, and 350 that were 
untreated. It was originally intended to ship the other lots at the 
same time. The car, however,-was found to be too small, so the 
borax-treated, salted, and limed spokes went forward at a later date. 

Many of the cold-creosoted spokes that had lain in the shed for 
two to three weeks awaiting shipment were slightly molded. It was 
noticed that those with the mold were taken from that part of the 
pile that had suffered most from poor ventilation, namely, near the 
bottom and in the rear. The spokes in the other lots at that time 
seemed to be free from mold or sap-stain. 

METHOD OF LOADING CAR NO. 1. 

The spokes were staeked in transverse ricks, beginning at the end 
of the car and working toward the doorway. Each rick was built 
up in the following manner. A row consisting of five pairs of spokes 


— 


49 BULLETIN 1037, U. S. DEPARTMENT OF AGRICULTURE. 


all parallel to the length of the car was laid across the floor. An 


interval of perhaps 1 or 2 inches separated the members of a pair, 
and the distance between successive pairs was made a little less _ 
than the length of a spoke. Upon either end of these was laid a ~ 
single transverse row of spokes. A third layer similar to the first — 
and a fourth similar to the second were then laid down. With two — | 


more alternate layers a comparatively open base six layers in height 
and providing for partial aeration of the ricks was constructed. 
Upon this base the remaining spokes of the rick were close piled in 
successive layers, two or three spokes in depth. Each alternate 
horizontal layer was placed at a slight angle to those directly above 
and below, but all had a general direction lengthwise of the car. 
-Each rick when built to within 2 feet or so of the roof contained 
on an average 833 spokes. As soon as one end of the car had been 
filled ricks were placed in the opposite end. In the doorway three 
longitudinal ricks were constructed and any space remaining was 
filled in with loose spokes. In this particular case one end of the 


car was stacked with the hot-creosoted spokes, the opposite end and ~ 


14 ricks in the doorway being stacked with the cold-creosoted spokes. 
Parts of two ricks in or near the doorway comprised spokes treated 
with mercuric chlorid, and the remainder consisted of untreated spokes 
thrown in loosely between the longitudinal ricks and the doorway. 
Both doorways were boarded up with 6-inch boards spaced 14 inches 


apart, and both doors were left open for about 1 foot. This car left — 


the yard on July 24, consigned to one of the large vehicle factories 
of the North and reached its destination on August 14. On August 
15 and 16 it was unloaded and inspected by C. J. Humphrey and the 
writer. During the time that the car was in transit the weather was 
in general hot and dry, although local showers may have been 
encountered, | 


CONDITION OF SPOKES IN CAR NO. 1 UPON ARRIVAL AT DESTINATION. 


The inspection at the time of arrival was very thorough, each spoke 
being handled separately and a record kept of the number showing 
mold in any degree. Observations were also made, in a general way, 
of the extent of sap-stain and incipient rot. No attempt was made to 
discriminate between heavy and light infections, as these largely 
depended, with a given preservative, on the position of the spokes 
in the ricks or in the car with respect to the amount of ventilation 
received. In general, the top-layers to a depth of 15 to 18 inches 
showed very little mold; likewise, the loosely arranged bases were 
‘quite free or comparatively so. The molds consisted for the most 


part of fluffy white to tawny mycelium, together with a compara- — 
tively small amount of green Penicillium. In the case of the cold- — 
creosoted spokes, there seemed to be an increase over the amount ~ 


; 
x 
2 


= 


SAP-STAIN, MOLD, AND DECAY IN GREEN WOOD. 43 


which was observed on the same spokes at the time of loading. For 
convenience in presentation, the data relative to location in the car 
and condition are given in Table I. 


TABLE aE ag oe of the red-oak spokes in car No. 1 upon arrival at its 


ojncr WwW 


destination. 
Percent- 
age 
f molded 
Location in car.a Antiseptic. ; Condition. (based on 
833 
spokes 
per rick). 
Jubinke end of the car: 
— in the door- | Untreated...........-. ne ony mold or sap-stain; a few badly |......_... 
checked. 
Stackedin the door- |} Mercuric chlorid and | None with mold or sap-stain; not so many |...._....- 
Rey, and first -hydrochlorie acid. checked asin the untreated lot. 
ric. 
jira i Ca Hate eae at 150° to | None with mold; nosap-stain._._.........../......-2.2. 
MOCO ICR S| eo 00). Se ee ad 68 with mold; no sap-stain...........222.... 8. 2 
"TOPO TiCKe <2 454.2 1555 GG. =. ee eee ae 431 with mold; nosap-stain...........22.... af ey 4 
PM MUG IL AIOK.- 2.5. -|-2-.- do... 33, eee 277 with mold; nosap-stain...........2...-- 33:2 
With TIeK Sts. Sk Go : 32 see. 218 with mold; nosap-stain................. 26. 2 
Sixth rick (end of |._.... 0. .: seas eet 222 with mold; nosap-stain-.-.............. 26. 7 
the car). 
Opposite end ofthecar: | 
Stacked in the door- | Cold creosote at 80° to | 69 with mold; no sap-stain.._............... &. 
wayandfirstrick.}| 90° F. 
Second rick.........]....- 00:-4 |2eeeseceee- 492 with mold; no sap-stain................- 59. 
Thirdwick. 2s...) ..00;... Seer es 348 with mold; nosap-stain............2.... 41. 
Fourth rick.........)....- GO... eee ee oe with mold; nosap-stain.-.........2..2.. 24. 
Fifth rick (end of |..... do:: ..\ ee ee 42 with mold; nosap-stain..-.............. 17. 
the car). b 


a Ricks are in each case numbered from the first transverse rick on either side of the area between the 


_ doors and extending back to the ends of the car. 


It will be seen from Table I that the spokes that were placed in the 
doorway where better ventilation could be had did not mold or 
sap-stain. Those that were the most exposed, however, were inclined 
to suffer from checking. The largest proportion of molding took 
place in the second or third ricks, but in no case was this accompanied 
by sap-stain, and in no instance was it severe enough to necessitate 
culling. The considerable reduction in the fourth and fifth ricks, 
which was most marked in the rear end of the car, is difficult to ex- 


plain. In the forward end, the motion of the train caused the last 


rick to slide away from the end of the car, and thus somewhat im- 


proved the ventilation. It is possible, then, that in the rear end the 


tendency of the mass of spokes to surge backward and forward when- 
ever the continuous passage of the car was interrupted, together with 
the fact that a hole existed in the bottom of the car due to the breaking 


of a floor plank, may have provided sufficient ventilation to account 


for the low percentage of mold in the fourth and fifth ricks. 
It was noted that the stage in the development of the mold on the 
ereosoted material was an early one, namely, a white, fluffy mycelium, 


u which in most cases had not advanced to the spore-producing condi- 


tion. This indicates a retarding effect due to the treatment. It is 


44 BULLETIN 1037, U. S. DEPARTMENT OF AGRICULTURE. 


also evident that the creosote, though unable entirely to control the 
mold, seemed to prevent the development of sap-stain. From the 
evidence it would also appear that heating the creosote to 150° or 155° 
F’. does not increase its effectiveness to any marked degree, the differ- 
ence in the percentage of moldy spokes in the two treatments being 
less than 1 per cent. 

METHOD OF LOADING CAR NO. 2, 

The second car, containing 1,032 salted, 1,013 borax-treated, 300 
lime-treated red-oak, and the remainder untreated, white-oak escort 
spokes, was loaded 
on August 3 and 5. 

Those spokes that 
had been salted were 
exceedingly moist, 
owing to the hygro- 
scopic property of 
the salt. On many 


ago 
c.@ 40 me Fi 


Se 
a 
© 


tie 


eke 
He; 
TT 


EI@ 


a 
Heh> Bw 


ad 


of these species of 
Penicillium were 


& 6 
we 


found. The limed 
spokes were dark in 
color and in a few 
cases seemed to be 
developing sap-stain. 
The borax-treated 
spokes were appar- 


He Be 
TLE 
Ogee 


6 

ow 

Ay wee 

rt 
Be olop 


ae 7. 
Ble 
| 


fungi. 
The method used 
-for stacking the 
spokes in the second 
car differed somewhat 
from that in the first. The base of each rick was constructed in 
the same manner, though of four instead of six layers. Upon this 
base the spokes were carefully stacked, using two 14-inch by }-inch 
crossers of elm between successive layers (fig. 19). Each rick held 
on an average 840 spokes. The doorways were closed in the same 
manner as in car No. 1. This consignment left the yard on August 
6 and arrived at the same factory located m the North on August 20, 
a period of two weeks in transit. During this time the weather was 
hot and comparatively dry. 


lig. 19.—“ Ricking,” or stacking, treated escort spokes in 
a box car (car No. 2). 


CONDITION OF SPOKES IN CAR NO. 2 UPON ARRIVAL AT DESTINATION, 


On August ‘21 the spokes were unloaded and inspected by C. J. 
Humphrey and the writer. Table II gives the location of the dif- 
ferent lots and their condition upon arrival. | 


. 


ently quite free from 


ge See 


SAP-STAIN, MOLD, AND DECAY IN GREEN WOOD. 45 


* 


TABLE II.—Condition of the spokes in car No. 2 upon arrival at its destination. 


Percent- 
age 
molded 
Location in car. Material. | - Antiseptic. Condition. (based 
Ln on 840 
spokes 
per rick). 
Ricks in the end of 
the car contain- 
ing treated spokes: 
First rick. ..... White oak. .| Untreated. .22222222.25.2.- 147 moldy; afew sap-stained 17.5 
Mid te. . A few untreated layersat top| 1 moldy..................... at 
Second rick - . Red oak... .. Remaining layers borax, 5 | 67 moldy; many sap-stained. 7.9 
per cent. 
ON 2 en Top layers borax, 5 per cent. d moldy ; many er ens y- .8 
Third rick ....do......| Middle layers lime... es 4 moldy; some sap-stained. . .4 
Bettie Spokes very darkin color. 
ado D. .:| Rottamiiager saltors 27S: 34 moldy ;some sap-stained . . 4.0 
Fourth rick....).....do...-.. Sellinet aa he a nee aS 300 moldy ; many with Pen-. SOT 
icilliumin all Barts ofrick, 
badly damaged. 
Fifth ribie 3 Se White oak. . Untreated. pea Ree es res 330 moldy; much sap-stain. . 39.3 
Sixthrick....../..... do BS Wl 210 on eg ee oa gis ae ..| 292 moldy; much sap-stain - . 34. 8 
Ricksin the door- 
way and in the 
opposite end of 
the car: 

' Indoorway....|.....do......]..... 32 ane Se aire ae Rene 4 No mold; no sap-stain....... 0 
Bipsh FICK 3.00 .|..% 2 @O~ 2-1.) Peace ape ee cee ee 87 moldy; many sap-stained. 10. 4 
Second rick. - te 2045.3: ..|. Farge Cc HT Oe aE? AS eae 312 moldy: many sap-stained 37.1 
ies to sixth Seip door 2... hee OO inl ccpaicieus = SEES Not examined fy. PS See 

ricks. 


The proportion of infected spokes, based on the total number in 
the different lots in the end of the car containing these spokes, is: 


cn no EO Ee ae ams a ae a 29 ~=per cent moldy. 
a ERE ES ace oe ee ge 5 le a 32. 3 per cent moldy. 
Pet iee SAGRCRLCG ) te cc a gt 7.3 per cent moldy. 
Rees tere ate) oh to Se ee sa ing 1. 3 per cent moldy. 


These figures can by no means be used as a basis for an exact com- 
parison of the values of the three preservatives. The location of the 
ricks in the car introduces another and very important factor. To 
note whether the hygroscopic property of the salt had a tendency to 
affect the humidity in the end of the car in which the salted spokes 
were stacked, thus influencing, perhaps, the amount of molding in 
adjacent lots, it was decided to observe the unloading of the spokes 
in the opposite end of the car. After two ricks had been unloaded, 
however, it became evident that this was not the case, as conditions 
in that end were practically the same as in the first. From the data 
derived, at least from this lot, given in Table II, it would seem that 
salt when applied dry to green spokes is of little value in controlling 
either sap-stain or mold. Lime, though effective in preventing both 
mold and sap-stain, yet because of its darkening effect on the wood 
and its tendency to form calcium carbonate, which cases over the 
_ surface and is said to dull the knives used in subsequent processes of 
manufacture, is debarred from further consideration. Borax, how- 
ever, with 7.3 per cent moldy spokes, seems to be somewhat effective 
_ against mold, but of less value in controlling sap-stain. 


46 BULLETIN 1037, U. S. DEPARTMENT OF AGRICULTURE. 


SUMMARY OF OBSERVATIONS. 


Creosote dipping seemed to prevent sap-staining, but it had little 
effect upon mold. In no way did it detract from the sale value of 
the spokes. 

The creosote bath at 80° to 90° F. was nearly as effective as at 150° 
to 155° F. 

Mercuric chlorid, 1 per cent, seemed to be very effective in con- 
trolling both sap- 
stain and mold. 

3 Borax solution, 5 
Zo emer per cent, appeared 
oe oe to be somewhat ef- 
Siemme te fective in control- 
Nic sa x otoom ome =. ling mold, but of less 
eer ee rE ~ 7 wo es value in regard to 
a pe sap-stain. 
@ Hom ee 3 oe Ob 2 The use of lime in 
o0menn » | MIE) «the treatment of 
spokes was not satis- 
factory, on account 
of its darkening ef- 
fect on the wood, the 
covering up of phys- 
ical defects, and the 
probability of dull- 
ing the knives used 
in later processes of 
manufacture. . 

Salt sprinkled over 
the spokes was of no 
value in preventing 
either mold or sap- 


" vii 
Aer g Ht Oe 


oy 


Vike 


— se 


OLE 


Fig. 20.—Green turned spokes cross piled in open or venti- stain. 


lated sheds. Green spokes are sometimes allowed to The ventilation ot 
surface dry in this manner for one to two months pre- wea’ b |. = 
paratory to shipping in box ears. spokes Ina DOx Carls x 


an important factor. 
Those spokes i in the doorway, even if untreated, usually have but little 
tendency to mold or sap-stain. : 
Practically none of the spokes in either car were culled on account 
of defects due to fungi, although a few in the areaway between the 
doors were thrown out on account of slight checking. 
No incipient decay was found in any of the material. 


. 


PUR) preset ing cy 


SAP-STAIN, MOLD, AND DECAY IN GREEN WOOD. 47 


EXPERIMENTAL DIPPING OF RED-OAK BLOCKS AT THE LABORATORY OF FOREST 
PATHOLOGY, MADISON, WIS. 


A comparison of the specific antiseptic values of the chemical sub- 
stances employed in the spoke-dipping experiments can hardly be 
‘made, since these substances were not used in solutions of uniform 
strength. To determine, if possible, the comparative values of these 
and several other common antiseptics and preservatives in the control 
of mold and sap-stain 
fungi, several series 
of experiments were 
undertaken at the 
Madison laboratory. 
Where possible, solu-: 
tions were made up 
to a calculated value 
of 1 per cent actual 
weight of anhydrous 
salt. The hygroscopic 
substances—sodium 
chlorid, calcium 


chlorid, and glyc- Fic. 21.—Storage of spokes in a warehouse. The truck 

a : spokes at the left have just been painted by girls with 
site aes added mM a resin-linseed oil mixture to prevent checking. 
certain instances to 


determine whether or not they would increase the efficiency of the 
preservative by keeping the surface of the treated wood moist. A 
list of the substances used follows: 


Alum (potassium). Potassium chlorate. 
Ammonium fluorid. Sodium fluorid. 
Bleaching powder. Sodium bifluorid. 
Borax. Zine silicofluor:d. 
Copper sulphate. Creosote. in kerosene. 
Lead acetate. Formalin. 

Lead nitrate. Lysol. 

Magnesium silicofluorid. Mykantin. 

Mercurie chlorid. : Orthonitrophenol. 
Mercuric chlorid and _ hydro- Rongalite. 


chloric acid, 1 per cent. 


-Red-oak blocks 2 by 2 by 14 inches long, sawed from the sapwood 
of summer-cut logs, were used in each case. Ten blocks constituted 
a group. The individual blocks of a group were immersed for ap- 
proximately 10 seconds in one of the respective solutions, drained, 
and then sprayed on all six sides with a water suspension of the 
spores taken from the same cultures as those used in the steaming 
__ experiments.** The sprayed blocks of each group were then close 
_ piled and placed in the tile chamber mentioned on page 29. An in- 


% See page 29 for the list of fungi. 


48 BULLETIN 1037, U. S. DEPARTMENT OF AGRICULTURE. 


terval of at least 15 inches was maintained between adjacent groups. — 
In the tile chamber the blocks were subjected to a temperature aver- 
aging 80° F. and a relative humidity varying from 85 to 100 per cent. 
At the end of three to four weeks all blocks were carefully examined. 
The following observations were made at that time: 

None of the preservatives was entirely effective in controlling 
mold when used in concentrations of 1 per cent. 

Blocks dipped in sodium carbonate, sodium bicarbonate, sodium 
fluorid, sodium bifluorid, ammonium fluorid, magnesium silicofluorid, 
zine silicofluorid, and bleaching powder became badly molded. 7 

Potassium (alum), potassium chlorate, and copper sulphate seemed 
to stimulate all or certain species of the fungi used. The last seemed 
to incite the ate the Cy ae of Aspergillus niger in particular. 


it eS ae ee oo a TITTIES 
arn 
I 
WY 
Pec) 
LEE 2 BO, CAR LOOKS OPEN 6 TOIOINGHES..~ —# =! he ee 
WAL Si S ACROSS FO HOLD OPEW. ge — 


NAL SonhaS IN FRONT OF OPENING TO Siig fp LOSS OF 
S7TAIES, GOARRO TOEXTEWO FAOMW FLOOR TOROOF. 


@IGHT WAY TO LOAD STRIPS 


N N IF STRIPS ARE 
BORRDO IM FRONT OF OPENING 7S INOICATED [i ALACLD FLAT ANO 
CAP LOYR OPEN 3 INIICATED H : 


TANS END OF CAR WLIW SHOWIN 

eens YR SOLS SHOULD RIPE ALONG 

SOLES PLOSTI G- “GE LONDED ENDS SLES OM CE, 
OALED. OF CA, 


Pe, STIPE 
PILED LENGTHWISE. 


WRONG WOR TO LOD STRIPF 


Fie. 22.—Diagram illustrating the method of loading used by one of the large wheel fac- 
tories and recommended by the wood-stock committee in connection with vehicle stock. 

Borax was effective in controlling the sap-stain fungus (Cerato- 
stomella sp.). Though it did not entirely prevent the growth of mold, 
the amount of mold that did develop was very slight in comparison 
with that on the blocks treated with the other preservative solutions. 
Under these circumstances it compared favorably with 1 per cent 
mercuric chlorid. 

The addition of the hygroscopic substances—sodium chlorid, cal- 
clum chlorid, and glycerin—to the solutions of the preservatives 
apparently did not increase their efficiency. 

Of the organic compounds and mixtures tested here, creosote in 
kerosene gave the best results, while mykantin stood second. The 
latter, however, stained the moed yellow, a property which would 
prohibit its use for many purposes. . 


SAP-STAIN, MOLD, AND DECAY IN GREEN WOOD. 49 


STORAGE OF GREEN DIMENSION, SAWED, OR TURNED STOCK AT THE MILL. 


If it becomes necessary to store dimension or turned green stock 
without giving it the protection referred to, cross piling or stripping 
in properly ventilated sheds is absolutely essential (figs. 20 and 
91). All strips should be narrow and at least. three-fourths of 
an inch, but preferably 1 inch, in thickness and should be thoroughly 
seasoned or given some antiseptic treatment. 


HANDLING GREEN DIMENSION, SAWED, OR TURNED STOCK IN TRANSIT. 


If it becomes necessary to ship green dimension, sawed, or turned 
stock and planks during the late spring and summer months, atten- 
tion must be paid to the cleanliness and ventilation of such tera 
while in transit.”* 
Cattle, vegetable, or 
ventilated box cars 
which have been 
previously cleaned 
are to be preferred 
for small stock. In 
ventilated box cars 
the end doors should 
be cleated open. If 
only box cars of the 
ordinary type are 
available, the ma- 
terial should be 
piled according to 
methods similar to 
the one shown in 
figure 22. In the 
case of spokes and 
sawed billets, a cross- 
piled foundation, 

four to six courses 
high, is recommended 
in addition to the 


directions given Fig, 23.—Artillery spokes “ ricked ” in a box car. Elm strips 
(figs. 93 and 94), one-half inch by 1% inches used between the courses. 


When doors of box cars are loosely boarded up (fig. 25) or cleated 
open (figs. 9 and 22), it is recommended that they be spiked, that the 
bill of lading bear an indorsement to the effect that the doors were 
left open and cleated at the request of the shipper, and finally that 


% The directions given under “ Provisions for the proper ventilation of stock in transit,” 
page 23, apply here. 
\ 


50 BULLETIN 1037, U. S. DEPARTMENT OF AGRICULTURE. 


a notice similar to that devised by one of the wheel companies — 


and cited in Bulletin No. 30 of the wood-stock committee ?* be nailed 
to the car, reading as follows: 

TAKE NOTICE.—Do not Ctose Doors.—The lumber in this car is 
green and is carefully cross piled that there may be good circulation of 
air through the stock. The doors are left partly open and cleated by the 
shipper upon request of the consignee. If the doors are closed the stock 
will be liable to damage in transit. 

Should this car break down in transit, making it necessary to transfer 
the stock to another car, it should be stacked in the car in the same 
manner and doors left open in the same way. 

The use of box cars is usually demanded -by those in charge of 
bending mills where green rim stock is to be shipped. These cars 
expose the stock to 
less damage from 
checking. Unless at- 
tention is paid to 
stripping or some 
method of. piling soas 
to insure ventilation. 
‘however, molding and 
sap-staining may re- 
sult. One method 
used for the-piling of 
rim strips in cars is 
shown in figure 26. 


Fic. 24.—Artillery spokes “ricked” in a box car. A SUMM ARY. 
cross-piled base, strips, and open-boarded doorway are 
important details in the provision for proper ventilation It is evident that 


of the stock while in transit. : 
the prevention of sap- . 


stain, mold, and incipient decay in green material, and in vehicle stock : 
in particular, lies in a combination of remedial factors, the following 
being especially important: Care in the selection of raw stock in ~ 
order to obtain, if possible, material free from fungous infections; — 
expedition in the movement of raw stock from the felling of the logs 
to that time in the process of manufacture when the material becomes 
sufficiently dry to resist the attacks of fungi; provision at all times 
for ample ventilation of the stock that it may quickly become at least 
surface dried, thus making it difficult for the fungous spores to obtain 
from the exposed sapwood the moisture necessary for germination; 


= 
a 
2 


26 National Implement and Vehicle Association and other Vehicle and Vehicle Parts 
Manufacturers. Information Division of the Wagon and Vehicle Committee and the 
Wheel Manufacturers’ War Service Committee. Wood Stock Committee. Sap-stain and 
mold in transit. Nat. Implement and Vehicle Assoc,, etc., Bul. 30, 5 p. 1918. A. B. 
Thielens, chairman. Typewritten. 


SAP-STAIN, MOLD, AND DECAY IN GREEN WOOD. 51 


the kiln drying of the stock wherever possible and whenever the cost 
will permit; and in special cases steam treatment or the use of anti- 
septic dips, followed by be) ie piling to insure ample ventilation. 
It must be continu- 
ally borne in mind 
that none of these is 
by itself a sovereign 
remedy. Preservative 
dips or steam treat- 
ment. were not in 
themselves, under the 
emergency manufac- 
turing conditions in- 
cident to the war, by 
any means sufficient 
to. control molding of 
Saipan stock when close Fig. 25.—A box car loaded with spokes and ready for ship- 


piled in storage ware- ment. Spaces of 14 inches are left between adjacent 
houses or while in boards nailed across the doorways to allow for venti- 


bytes lation of the stock while in transit. 
transit in box cars. 


In connection with this investigation, it should also be borne in 
mind that we are dealing with three distinct groups of fungi, namely, 
the molds, staining organisms, and true wood- -destroying organisms, 

the antiseptics being more ficient against the last two groups than 
the first. As far as 
is known, neither. 
molds nor staining 
fungi cause any ap- 
preciable diminution 
in the strength of 
timber and hence are 
Fie. 26.—Zigzag method of piling rim strips in box cars. unimportant in ve- 
- hicle manufacture from the standpoint of strength and probably 
durability. The staining fungi can be controlled to a certain extent 
by the intelligent use of antiseptics and possibly by steaming, and 
it seems reasonable, in the light of experience, to suppose that the 
development of wood-destroying fungi can also be prevented. 


(1) 


(2) 
(3) 
(4) 


(5) 


(6) 


(7) 


(8) 


(9) 


(10) 


(11) 


(12) 


(13) 


(14) 


(15) 


(16) 


‘ LITERATURE CITED. TNs 


Aso, Krrsrro. : aes  @ 


1901. On the réle of oxydase in the preparation of commercial tea. In 
‘ Bul. Col. Agr., Tokyo Imp. Univ., v. 4, no. 4, p. 255-259. 

1902. On oxidizing enzyms in the vegetable body. In Bul. Col. Aer. 
Tokyo Imp. Univ., v. 5, no. ‘2, p. 207-235. . 

1903. On the chemical nature of the oxidases. Jn Bul. Col. pe Tokyo 
Imp. Univ., v. 5, no. 4, p. 481-489.. 

1905. Further observations on oxidases. In Bul Col. ‘co Tokyo 
Imp. an i 6, no. 4, p. 371-374. 2 eS 

BAILEY, IRVING W. 

1910. Oxidizing enzymes and their relation to “ sap stain” in lumber. 

In Bot. Gaz:, V. 50,- “no. 2, p. 142-147. 
BERKELEY, M. J. _ 

1876. Notices of North American fungi. Nos. 927-932.. Sphaeria jun- 

cina — Sphaeria semiimersa. In Grevillea, v. 4, no. 32, p. 146. ° 
BETTS, HaARotp §S. 

1917. The seasoning of wood. U. S. Dept. Agr. Bul. 552, 28 p., 8 pl, 

18 fig. 
CLARK, ERNEST DUNBAR. 

1910. The plant oxidases. 113 p. Easton, Pa. ee p. 94-111. 
Diss.—Columbia Univ. 

1911. The nature and function of the plant oxidases. Im Torreya, v. 
11, no. 2, p. 23-81; no. 3, p. 55-61; no. 4, p. 84-92, 101-110. 
Supplementary bibliography of papers.recently published, p. 
109-110. 

E.1is, J. B.;} and EvERHART, B. M. 
1892. The North American P ronciasaeece A contribution to o-mpenlanié 
botany, 11, 3, 792 p., 41 pl. Newfield, N: J. 
FRANK, A. B. 
1895. Die Krankheiten der Pflanzen ... Aufl. 2, Bd. 1. Breslau. 
FREEMAN, E. M. a 
1905. Minnesota Plant Diseases. xxiii, 432 p., illus. St. Paul. (Minn. 
Geol. and Nat. Hist. sat coin Rpt. Bot. Ser. V.) 
FRIES, ELIAS. 
1823. Systema mycologicum. ..v. 2. Lundae. 
FUCKEL, LEOPOLD. 

1869-70. Symbolae ay boicehs: Beitrige zur Kenntniss der Rhein- 
ischen Pilze. 459 p., 6 pl. Wiesbaden. (Jahrb. Nassau. Ver. 
Naturk., Jahrg. 23/24.) . 

Gum LuMBER MANUFACTURERS’ ASsocIATION. 'Technical Research Com- 
"mittee. . 
1914. Digest [of report]. Jn Lumber World Rev., v. 26, no. 10, p. 44. 
Haas, Pau, and Hii, T. G. 

1913. An introduction to the chemistry of plant products. 401 p. Lon- — 

don. 


‘ SAP-STAIN, MOLD, AND DECAY IN GREEN WOOD. | 53 


Hartie, ROBERT. 

1878. Die Zersetzungserscheinungen des Holzes der Nadelholzbiume und 
der Hiche in forstlicher botanischer und chemischer Rich- 
tung =. . Berlin. 6, 151 p., 21 pl. (15 col.}. 

1900. Lehrbuch der Pflarzenkrankheiten. Fiir Botaniker, Forstleute, 
Landwirthe und Gartner ... Aufl. 3. 9, 324 p., 280 fig., 1 col. 
pl. Berlin. i 


HEpDGCOcK, GEORGE GRANT. 
1906. Studies upon some chromogenic fungi which discolor wood. Jn 
Mo. Bot. Gard. 17th Ann. Rpt., p. 59-114, 3 fig., pl. 3-12. 


1911. Prevention of mold. Jn Barrel and box, v. 16, no. 4, p. 35. 


HUBERT, E. E. 
1921. Notes on sap-stain fungi. In ee eee Vil: e" 5. 


HUMPHREY, 30 e 2 
1917. Timber storage conditions in the Eastern and Southern States 
with -reference to decay problems._U. S. Dept. Agr. Bul. 510, 
43 p., 10 pl., 41 fig. 
[1920.] The decay of ties in storage. 35 p., 8 m.. in text (pl. 1-3 
col.) Baltimore. 


—— and FLEMING, RUTH M. 
1915. The toxicity to fungi of various oils and salts, particularly 
those used in wood preservation. 38 p., 4 pl. Bibliography, 
p. 37-38. | 
HUNT, GEORGE M. 
1916. The preservative treatment of farm timbers. U.S. Dept. Agr., 
Farmers’ Bul. 744, 32 p., 17 fig. 
JANKA, GABRIEL, | 
1907. Die Einwirkung von Siiss- und Salzwiissern auf die gewerblichen 
-EHigenschaften der Hauptholzarten. Teil I. Untersuchungen 
und ergebnisse in mechanisch-technischer Hinsicht. Jn Mitt. 
Forstl. Versuchsw. Osterr., Heft 33, p. 1-96, 16 fig. 


KASTLE, J. H. 
1910. The oxidases and other oxygen-catalysts concerned in biological 
conditions. U. &. Hyg. Lab. Bul. 59, 164 p. References to 
the literature, p. 141-161. 


LAFAR, FRANZ. 
1903. Technical Mycology: the Utilization of Micro-Organisms in the 
Arts and Manufactures. A Practical Handbook on Fermenta- 
ON, 5... Vee, Dt.,d.. London, 


LINDAU, GUSTAV. 
1897. Sphaeriales. Jn Engler, Adolf, and Prantl, Karl. Die Natiir- 
lichen Pflanzenfamilien ... Teil 1, Abt. 1, p. 384-491, fig. 
252-288. Leipzig. 


eecera, I. G., and ScaALeEs, F. M. 

1913. The destruction of cellulose by bacteria and filamentous fungi. 
U.S. Dept. Agr., Bur. Plant Indus., Bul. 266, 52 p., 4 pl. 
Bibliograpny, p. 47-50. 

. Miwon, ERNST. 

1907-08. Die Blaufiule aes Nadelholzes. In Naturw. Ztschr. Land. 
u. Forstw., Jahrg. 5, Heft 11, p. 531-573, 1907. Jahrg. 6, 
Heft 1, p. 32-47; Heft 6, p. 297-323, 1908. 33 fig. 


54 BULLETIN 1037, U. S. DEPARTMENT OF AGRICULTURE. | 
(32) 1909. Untersuchungen tiber ears und Krankhettsemfinglich eit 


7, Heft 1, p. 5475 ; Heft 2, p. 87-114; Heft < p. 129-160, 
D fig. 


(33) NORDLINGER, HERMANN VON. 5 
1860. Die technischen Eigenschaften der Hdlzer fiir Forst- und Bau- — 
beamte Technologen und Gewerbtreibende. 16, 550 p., 102 fig. 

Stuttgart. 


(34) Pratt, Merritt B. ‘ > : 
1915. The deterioration of lumber. (A preliminary study). Cal. Agr. E 
Exp. Sta. Bul. 252, p. 297-820, 8 fig. References, p. 320. 


~ 


(35) RotH, FILIBERT. 
1895. Timber: an elementary discussion of the characteristics and 
properties of wood. U. S. Dept. Agr., Div. Forestry Bul. 10, 

88 p., 49 fig. 


(36) RupeLorr, M. 
‘1897-99. Untersuchungen tiber den Einfluss des Blauwerdens auf die 


Festigheit von Kieferholz. In Mitt. K. Tech. Vers. Anst. Ber- ; 
lin. Theil I-Bd. 15, Heft -1, p. 1-146, fig. 1-55, pl. 1-14. Theil : 
2-Bd. 17, Heft 5, p. 209-239, fig. 1-9, pl. 1-9. | 
(37) RUMBOLD, CAROLINE. Fi 


1911. Uber die Einwirkung des Siiure- und Alkaligehaltes des Nihr- — 
bodens auf das Wachstum der holzzersetzen den und holz- — 
farbenden Pilze; mit einer Erérterung tiber die systematischen 
Bezichungen zwischen Ceratostomella und Graphium. In 
Naturw. Ztscbr. Land u. Forstw., Jahrg. 9, Heft 10, p. 429- E; 


466, illus. a 
(38) 1911. Blue stain on lumber. Jn Science, n. s., v. 34, no. 864, p. 94-96. ; 
(39) Saccarpo, P. A. Renate 


1878. Fungi veneti novi vel critici vel mycologiae venetae addendi. 
Series 9. Jn Michelia, v. 1, no. 4, p. 361-434, 


(40) —- 1882-1918. Syiloge fungorum . . . y. 1, 1882; v. 2, 1883; v. 9, 
1891; v. 11, 1895; v. 14, 1899; v. 17, 1905; v. 20, 1911; v. 22, 
1913. Patavii. 


(41) ScHRENK, HERMANN VON. 3 
19C3. The “bluing” and the “red rot” of the western yellow pine, — 
with special reference to the Black Hills forest reserve. U. 8. 
Dept. Agr., Bur. Plant Indus. Bul. 36, 40 p., 14 pl. (1, 38, 5, 
and 9 col.) 


(42) 1907. Sap rot and other diseases of the red gum. U.S. Dept. Agr., Bur. 
Plant Indus. Bul. 114, 37 p., 8 pl. 


(43) 19:0. Prevention of blue stain in lumber. Jn St. Louis Lumberman, 
v. 46, no. 1, p. 60-61, illus. 


and SPAULDING, PERLEY. 
1909. Diseases of deciduous forest trees. U. 8S. Dept. Agr., Bur. Plant 
Indus. Bul. 149, 85 p., 11 fig., 10 pl. Bibliography, p. 69-73. 
(45) SHERFESEER, W. F. 
1909. Wood preservation in the United States. U.S. Dept. Agr., Forest 
Serv. Bul. 78, 31 p., 4 pl., 3 fig. 


SAP-STAIN, MOLD, AND DECAY IN GREEN Woop. 55 


4 (48) SmirH, A. LORRAIN. 

1918. Hyphomycetes and the rotting of timber. Jn Trans. Brit. Mycel. 

A Soc., v. 6, pt. 1, p. 54-55. 

_ (47) SNELL, WALTER H. 

1921. The relation of moisture contcnt of wood to its decay, with spe- 
cial reference to the spraying of log piles. In Paper Trade 

3 Jour., v. 72, no. 18, p. 44, 46. 

- (48) SpauLprne, PERLEY. 

, 1906. Studies of the lignin and cellulose of wood. In Mo. Bot. Gard., 
17th Ann. Rpt., p. 41-58, 2 col. pl. 

(49) TEESDALE, C. H. 

1916-17. Use of fluorides in wood preservation. Jn Wood-preserving, 
v. 3, no. 4, p. 80-81; 1916, v. 4, no. 1, p. 6-10, 1917. Bibliog- 

eC raphy, p. 10. 

(50) TEESDALE, L. V. 

1920. Manual of design and installation of forest service water spray 
dry kiln. U.S. Dept. Agr. Bul. 894, 47 p., 13 fig. (in text and 
on 1 pl.). 

_ (51) Tremann, Harry D. 

. [1917.] The kiln drying of lumber. A practical and theoretical trea- 
tise. Ed. 3; 11, 316 p., 54 fig. and 8 diagr. (in text and on pl.). 
Philadelphia and London. 

_ (52) 1917. The theory of drying and its application to the new humidity— 

regulated and recirculating dry kiln. U.S. Dept. Agr. Bul. 509, 

28 po fig. 

53) U. S. DEPARTMENT OF AGRICULTURE. Forest Service. 

1920. Timber depletion and the answer. A summary of the report on 
timber depletion and related subjects prepared in response to 
Senate Resolution 311. U.S. Dept. Agr., Forest Serv. Cire. 112, 
16 p. 

(54) «1920. Timber Depletion, Lumber Prices, Lumber Exports, and Con- 

centration of Timber Ownership. Report on Senate Resolution 

; oll. 71 p.,.22 fig. Washington, D. C. 

(55) Warp, H. MarsHAtt, 

1898. Penicillium as a wood-destroying fungus. Jn Ann. Bot., v. 12, 

no. 48, p. 565-566. 

(56). WEIss, Howarp F., 

1915. The preservation of cnarnl fiinber ~ 1S, 312. p., 32. fig,, > 47 
pl. New York and London. 


and BarNuM, CHARLES T. 

1911. The prevention of sap stain in lumber. U. S. Dept. Agr., Forest 

% Serv. Circ. 192, 19 p.; 4 fig. 

_ (58) WINTER, GEORG. 

a 1887. Die Pilze Deutschlands, Oesterreichs und der Schweiz. ... Abt. 
2. In Rabenhorst, Ludwig. Kryptogamen—Flora.... Aufl. 

. 2. Bd. 1. Leipzig. . 

_ (59) Yosuma, HrKoroKuro. 

1883. Chemistry of lacquer (Urushi). Part I. Jn Jour. Chem. Soc. 

[London], v. 48, p. 472-486. 


(57) 


“3 Soe oie: ee: j qe ee 
- ' 4 ,' rie m 4 * 
} 3 _ i) ee 
: “ ft Sie Rio? 
; : Pie eee ae 
, 
é s > b f. -» 
3 veo & her ee ; id az +) ere ee “PESLER LE 
< rc! 7 ‘ cy Fede hay 
é mb. at ee 
‘ iu My 
BG, 
patie Ye Yin f und $5, : utp sae 
» - =<. we 
. § ct. 7 : #~ 4 etfs = eis m 
/ = ¥ 


_* Ca 7. ree “THE SUPERINTENDENT OF DOC UD 
GOVERNMENT PRINTING OFFICE 
pe coean Se D. C. 


e oh ¢ : : ‘AT > Beaeubte Le 


« . 


US iS Ste ae 
— i f ; 
P i 
. ’ - 
— ra) 7 
/ 4 - ¢ 
q ; aL 
F Vinee “Fd 2 IF 
< : ‘ 
‘ > Peso 3 J a5 
ee ae 
tt by pe 
. Dy 
t = ; 
= Na } Ai), CRORE 
s . 
ee, 4 
i V/s 
. : 
= “ el 
> 
py > - 
, 2 
> f 
¥ J fh 
* Ma ‘ : 


py 


UNITED STATES DEPARTMENT OF AGRICULTURE 


BULLETIN No. 1053 


Contribution from the Bureau of Plant Industry 
WM. A. TAYLOR, Chief 


Washington, D. C. PROFESSIONAL PAPER May, 1922 


STUDIES OF CERTAIN FUNGI OF ECONOMIC IMPORTANCE 
IN THE DECAY OF BUILDING TIMBERS, WITH SPECIAL 
REFERENCE TO THE FACTORS WHICH FAVOR THEIR 
DEVELOPMENT AND DISSEMINATION. 


By Watters H. SNELL,” Forest Pathologist, Office of Investigations in Forest 


Pathology. 
CONTENTS. 
} Page. Page. 
| WritroGuctien= 24a eet yee oLa 1 | Mycelium—Continued. 
amgigenores. 4 + Differentiation of the cultures 
j Sources of basidiospore ma- WOM adie se See of 
Oo eee 4 Effect of temperature on the 
Methods used in the basidio- growth of the mycelium___.. 25 
Spore sscuuies——__ ______--_~ 5 | Secohdary Ispores! 7.2 se oo 2¢ 
Germination of the  basidio- Intramural dissemination § of 
0S ae ae 5 fungi causing decay_______~_ 26 
Retention of the viability of Review of the literature of 
the basidiospores _____---__ 11 secondary spore formation__ 27 
Observations on the casting of Occurrence of the secondary spores 
the basidiospores __________ 14 in cultures of the fungi studied__ 30 
- Observations on the dissemina- Germination studies of the second- 
tion of the basidiospores of BT ye SDOLCS 22 cee ee 32 
Trametes serialis __-_________ 16 | Experiments upon the dissemination 
maemieclimeieee: Jaffee je) 19 of the oidia of Lenzites sepiaria__ 36 
Preparation of cultures_______ 19 Occurrence in buildings of the 
Macroscopic appearance of cul- secondary spores of the fungi 
tures grown at room tem- etndied= is se no sas ee ted ne 38 
Sa oe 19 SONNE sex ere eee 38 
Microscopic characters of the itermvume ‘cited ss Teeiie he on 42 
mycelia on malt agar_______ 22 
INTRODUCTION. 


There is no means of estimating the total annual loss occasioned 
by fungi which attack timbers in buildings, but from the evidence at 
hand it is certain that this loss is very large. This is particularly true 
in textile mills, paper mills, and canning factories, in which high 


1The writer wishes to acknowledge his indebtedness in connection with these studies 
_to Prof. L. R. Jones, of the department of plant pathology of the University of Wis- 
consin, for his interest, encouragement, and criticisms; to Mr. C. J. Humphrey, of the 
Office of Investigations in Forest Pathology, Bureau of Plant Industry, Madison, Wis., 
under whose immediate direction this work was undertaken, for general supervision, 
facilities, and criticisms; and to Mr. F. J. Hoxie, engineer and special inspector for the 
Associated Factory Mutual Fire Insurance Companies of Boston, Mass., for courtesies 
tendered in connection with mill investigations and for the loan of photographs. 


82278—22 i 


4 BULLETIN 1053, U. S. DEPARTMENT OF AGRICULTURE. 


humidities and moderately high temperatures prevail throughout the 
year. Such conditions provide a very favorable environment for the 
development of wood-decaying fungi, and this condition is ag= 
gravated by the quality of timber which has been on the market in 
recent years. The timber formerly used in mill construction consisted 
in many cases of white pine and white oak, both of which are highly 
durable woods. In more recent years, however, these timbers have) 
been supplanted largely by southern yellow pine, spruce, and hem- 
lock. High-grade resinous longleaf pine has given good service 
under exacting conditions, but the inferior grades of pine, often of 
more rapid growth and frequently containing a high percentage of 
sapwood, have not proved satisfactory in parts of buildings where the 
conditions are favorable for decay. Likewise, spruce and hemlock 
have given poor service under similar conditions. Furthermore, 
such timbers may be left in the open for protracted periods, exposed 
to the weather and infection by fungi, or may be put in buildings in: 
a partially seasoned condition, and after a short period replacement. 
is necessary, involving not aie the direct expense of repairs but also 
loss of operating time. 

Hoxie (24, p. 2)? reports that 30 cases of rot of greater. or less 
magnitude have come to his attention within three years. He states 
that “several million feet of lumber were involved, and in some of 
the worst cases the safety of important structures was menaced. 
* * * The direct money loss to Mutual members (Associated Fac- : 
tory Mutual Fire Insurance Companies, Boston, Mass.) * * * is 
undoubtedly many thousand dollars each year, in addition to the in-' 
creased life and fire hazard from loss of strength and greater coma 
bustibility of rotting structural timbers.” 

The following specific examples from Hoxie’s records may be of 
interest to show the magnitude of the loss. In a Connecticut mill 
the roofs of weave sheds, built in 1906 and 1909, were so seriously 
rotted in 1916 that it was estimated that 40,000 feet of plank would 
be necessary for repairs. The older roof in many places was not 
safe to walk upon and had settled so that there were hollows sup- 
ported practically only by the tarred paper. In one Massachusetts 
cotton mill built in 1900, 85 per cent of the roof planking and a 
large proportion of the floor supports had rotted and had been re- 
placed by hemlock, in some cases twice between 1908 and 1914. It was 
found that hemlock, put in green, lasted about two years. It was, 
estimated that over 1,000,000 feet of lumber had been used in the 
construction of this mill in 1900, at a cost of $30,000, and the re- 


2'The serial numbers in parentheses (italic) refer to “ Literature cited” at the end 
of this bulletin. 


FUNGI OF IMPORTANCE IN THE DECAY OF TIMBERS. 3 


placements during the four years prior to 1914 required about 240,000 
feet of lumber at a cost of more than $6,100. In another Mecce 
chusetts cotton mill, one weave shed, built in 1910, by 1916 was 
affected with decay throughout, and in another shed ae the same mill 


_ parts of the roof were replaced in 1914, 1915, 1916, and 1917, neces- 


“Ae 


sitating the use of 1,000,000 feet of lumber in 1916 and 30,000 feet the 
next year. A Canadian mill, built in 1908 with beams of supposedly 
“first-class Georgia longleaf” pine, was thoroughly rotted by 1911, 
and the beams were replaced by steel. 

Blair (2) gives some similar data with regard to the decay of paper- 


mill roofs. He found that of 80 mills visited, 12 had made renewals 
_ just prior to 1920, 17 were to make renewals in 1920, and 24 others 


would be compelled to make renewals within a short time after that 
date. Of the roofs which were being replaced in 1920 the service had 
been-5 to 19 years, with an average of 8 to 10 years. 

The foregoing data show that considerable pecuniary losses were 


_ occasioned by the action of decay-producing fungi in mills, even when 


_ the prices of lumber and labor were comparatively moderate. With 


the recent high cost of both these factors, the figures become much 


more impressive. In one Massachusetts cotton mill replacements 


made during the summer of 1920 in the roof of a weave shed approxi- 
mately 1,000 by 300 feet cost the owners between $100,000 and $125,000. 

In Europe the problem of decay in buildings is of long standing and 
has received considerable attention. Much has been written from sev- 
eral points of view upon the decay caused by Merulius lacrymans, in- 


cluding the engineering and legal as well as the mycological and 
- biological factors. Also, the decays caused by Coniophora cerebella, 


Portia vaporaria, and species of Lenzites have been particularly 


studied. In this country the study of timber decay in buildings on 
a comprehensive scale is only beginning, and thus far the work has 
largely been confined to Merulius lacrymans and its relatives and to 


_ Contophora cerebella. In mills and other structures in which condi- 
_ tions favorable for fungus growth prevail, other organisms probably - 
_ do more damage than these, but have as yet received little attention as 


Ae 
ut 


structural-timber destroying organisms. 


Because of the practical importance of the decays caused by these 


. ~ * a a2 
ree A <= 
° 


_ other fungi in textile mills, etc., the writer has undertaken to make 
" some preliminary studies upon Re Hs of them (Lenzites sepiaria, 

me. trabea, Trametes serialis, Fomes roseus, and Lentinus lepideus) , 

"especially with regard to fete PE oaiclostent relations of the my- 

_celium, basidiospores, and secondary spores where they occur. Within 

the time and facilities at his disposal, as much attention as possible 
e has been paid to those factors influencing the intramural dissemina- 
» tion of these forms. 


A BULLETIN 1053, U. S. DEPARTMENT OF AGRICULTURE. 


Lenzites sepiaria has been studied as a destroyer of coniferous ti m- 
bers in buildings by Falck (75) in Europe and out of doors by Spauld- 
ing (58) in this country.’ Its importance in the destruction of mill 
roofs “was suspected by Hoxie (24) in 1915, and since then he and 
others, including the writer, have found it Evan quite commonly B 
and doing bh damage in such places. (PI. I, figs. 1 and 2.) Len-— 
zites trabea has been reported by Blair (1) as destroying weave-shed | 
roofs. This species, though usually found upon hardwoods in nature, | 
probably occurs more commonly and is more destructive to coniferous — 
lumber under mill conditions than has yet been reported. The writer © 
has found it fruiting upon yellow pine and spruce roofs. (PI. I, 
figs. 3 and 4.) 

Trametes serialis has been found upon some of tdi more badly de- — 

cayed roofs along with other fungi (PI. I, fig. 5; Pl. I, figs. 1 and 2), 
but within buildings it is usually upon Hadeinisilt tioientl This fungus © 
generally occurs in the resupinate form and also forms abortive struc- 
tures. 

Fomes roseus is found within mills upon beams in moist basements | 
(PL II, fig. 5). The annual form is the one of common occurrence, and ~ 
whether or not the perennial form also occurs is not certain. Many 
mycologists consider the annual form as a distinct species, Trametes — 
carned. 

Lentinus lepideus has been found upon roof timbers mrs very 
moist conditions and in basements (Pl. II, figs. 3 and 4). It also — 
occurs in Europe on building timbers (cf. Mez, 35; Falck, 17.) Itsq 
destructiveness to structural timber in the open is well known. : 


BASIDIOSPORES. 


SOURCES OF BASIDIOSPORE MATERIAL. 


The basidiospores used were obtained for the most part from fruit 
bodies collected in the field. Those of Lenzttes sepiarta were from | 
various collections in Wisconsin. The spores of Lenzites trabea were 
obtained from fruit bodies upon pulpwood bolts, collected in Penn- | 
sylvania, by F. J. Hoxie. The basidiospores of Trametes seri- | 
alis were obtained from fructifications on some rotten timbers. (re- 
moved on account of decay) from the pulp-and-paper section in the 
Forest Products Laboratory and placed in the forest- pathology 
greenhouse. From two or three small sporophores formed in No-— 
vember, 1919, sufficiently large numbers of spores were obtained to 
last uae two winters of experimentation. Sporophores | of the 
annual form of Yomes roseus were collected upon tamarack (Laria 
laricina) logs in Wisconsin and red spruce (Picea rubens) in New 
Hampshire. The spores of Lentinus lepideus were obtained from | 
sporophores collected by Mr. Hoxie in a cotton mill in Massachuset 


~e 


Bul. 1053, U. S. Dept. of Agriculture. PLATE lI. 


FUNGI OF ECONOMIC IMPORTANCE IN THE DECAY OF BUILDING TIMBERS.—I. 
(Figures 1, 2, and 5;were photographed by F. J. Hoxie.) 


Fic. 1.—Sporophores of Lenzites sepiaria on planks of weave-shed roof which was originally 
sheathed. (xX +.) Fia.2.—Sporophores of Lenzites sepiaria from cotton-mill roof. (x 3.) 
Fic. 3.—Sporophores of Lenzites trabea from cotton-mill roof, same as that shown on roof plank 
in figure 4. (xX 3%.) Fia. 4.—Lenzites trabea fruiting body between planks of cotton- mill roof. 
> +) Fig. 5.— Trametes serialis fruiting upon planks of a roof which was originally sheathed. 

X ¢ 


Bul. 1053, U. S. Dept. of Agriculture. PLATE II. 


FUNGI OF ECONOMIC IMPORTANCE IN THE DECAY OF BUILDING TIMBERS.—II. 
(Photographed by F. J. Hoxie.) 


Fig. 1.— Tramestes serialis fruiting around belt hole in a weave-shed floor. (xX 4.) Fig. 2.— 
Fruit body of Trametesfserialis on planking in basement of cotton mill. (XxX 4.) Fies. 3 and 
4.—Fruit bodies of Lentinus lepideus on planking of weave-shed roof which was originally 
Coe (X 3.) Fic. 5—Fomes roseus fruiting on ceiling planks of basement of cotton mill. 

xX 


Bul. 1053, U. S. Dept. of Agriculture. PLATE III. 


< lt dae 


BASIDIOSPORE STUDIES OF LENZITES SEPIARIA. 
(X 475, except la, which is X 67.) 


Fic. 1.—Germinating basidiospores on malt agar. Fic.-la.—Extent of the growth which may 
take place before branching begins. Fic. 2.—Germinating basidiospores in distilled water. 
Fic. 3.—Oidia upon submerged mycelium in agar. Fic. 4.—Septate oidium. Fias. 5,6, and 
7.—Aerial mycelium almost completely broken up to oidal chains. Fic. 8.—Coil in aerial 
mycelium of older cultures. Fic. 9—Germinating oidia. Fic. 10.—Successive stages in 
formation of oidia and one chlamydospore in submerged mycelium in agar, with germination 
of the chlamydospore. Fic. 11.—Stages in the germination of a single oidium. FIG. 32.— 
Stages in the formation of chlamydospores in submerged mycelium. Fic. 13.—Chlamydispores 
or chlamydosporelike bodies. 


Bul, 1053, U. S. Dept. of Agriculture, 


PLATE+FVe 


BASIDIOSPORE STUDIES OF LENZITES AND TRAMETES. 


(X 475.) 


Fig. 1.—Germinating basidiospores of Lenzites trabea on malt agar. Fic. 2.—Oidia of Lenzites 
trabea from secondary aerial mycelium on malt agar. Fic.3.—Stages in formation of 
chlamydospores upon submerged mycelium of Lenzites trabea in malt agar. Fig. 4.—Chlamy- 
dospores and chlamydosporelike bodies of Lenzites trabea upon submerged mycelium in malt 
agar, one of them germinating. Fic. 5.—Germinating basidiospores of Tramestes serialis on 
malt agar. Fic. 6.—Stages in formation of chlamydospores of Z'rametes serialis on malt agar. 
Note contraction of protoplasm and formation of walls. Fic. 7.—Chlamydospores of Trametes 
serialis from submerged mycelium in malt agar. Fic. 8—Chlamydospore of Trametes serialis 
on aerial mycelium in malt agar tube, showing old walls. Fic. 9.—Germinating chlamydo- 
spores of Trametes serialis on malt agar. Fiac. 10.—Irregular hypha from tertiary mycelium of 
Trametes serialis at top of agar slant culture. Fic. 11.—Sprouting of clamp of Trametes serialis. 


Fia. 12.—Clamps, anastomosing of hyphe, and other irregularities from agar slant cultures of 
Trametes serialis. 


we. SOW ow: oe iy, 


Bul. 1053, U. S. Dept. of Agriculture. PLATE V. 


VSS ‘ 


BASIDIOSPORE STUDIES OF FOMES AND LENTINUS. 


(X 475.) 


Fig. 1.—Germinating basidiospores of Fomesroseus on malt agar. Fic. 2.—Germinating basidio- 
spores of Lentinus lepideus on malt agar. Fic. 3.—Anastomosing of hyphe, one from clamp, 
of Lentinus lepideus. Fic. 4.—Chlamydospore from aerial tertiary mycelium of Lentinus 
lepideus on malt agar. Fic. 5.—Chlamydospores of Lentinus lepideus on submerged mycelium, 
in malt agar. Fig. 6.—Mature and immature chlamydospores from colored mycelium over- 
growing gills of sporophore of Lentinus lepideus, collected in a Massachusetts cotton mill. 
Fig. 7—Wavy branch from aerial mycelium of malt agar culture of Lentinus lepideus. Fia. 
8.—Types of anastomosing of mycelium of Lentinus lepideus on malt agar. Fie. 9.—Clamps 
from aerial mycelium of Lentinus lepideus on malt agar. Fic. 10.—Basidiospores of Lentinus 
lepideus germinating upon red spruce. 


Bul. 1053, U. S. Dept. of Agriculture. PLATE VI. 


Fic. I.—DISSEMINATION OF BASIDIOSPORES OF TRAMETES SERIALIS BY 
IMPERCEPTIBLE CURRENTS OF AIR IN A CLOSED PIT. 


The sporophore at A naturally dropped spores downward, but in the closed pit there were air 
currents of sufficient magnitude to carry the spores upward to be deposited at points marked 
J85, {Oer55)) 


FIG. 2.—DISSEMINATION OF TRAMETES SERIALIS. 


Basidiospores of T'rametes serialis on the leg of a sow bug caught in condensation water beneath 
the sporophore in fungus pit at Madison, Wis. (xX 250.) 


FUNGI OF IMPORTANCE IN THE DECAY OF TIMBERS. , is 
METHODS USED IN THE BASIDIOSPORE STUDIES. 


The basidiospores used in the tests were collected and kept on 
sterilized glass slides, as a rule, although the spores of Lentinus 


_ lepideus were collected upon sterilized black paper. The spore 


prints were obtained in the usual way, care being taken to prevent 


moisture from collecting upon the prints for it was found early in 
the work that such condensation water affected the viability of the 
spores. The prints were then preserved in Petri dishes in an ice 
box in which the temperature was 12° to 16° C., and the relative 
humidity 40 to 45 per cent. For the general purposes of experi- 
mental work the glass slides for spore prints were preferred to the 
black paper because of ease of manipulation and cleanliness. 

All spore germination tests were made upon the surface of agar, 
usually in Van Tieghem cells. The germination of spores upon the 
surface of the cooled agar had certain advantages. The question 
of the oxygen supply available for the spores was obviated. It was 
easier to count percentages of germinated spores when they were all 
in one plane. And besides there was no danger of subjecting the 
spores to unfavorable temperatures, as may be the case when they 
are introduced into melted agar. A temperature only slightly too 
high, produced either by a hot needle or hot agar, materially reduces 
the percentage of germination. For purposes such as drawing, 
photography, or examination by the higher powers of the microscope, 
sowings of spores were made upon thin films of agar poured on 
sterile slides kept in moist chambers under sterile conditions. The 
agar media used for all experimentation contained 2 per cent of 
agar with 24 per cent of malt extract, filtered through filter paper in 
a Biichner filter and autoclaved 30 minutes at 8 pounds pressure. 
Occasionally, for the taking of photomicrographs, water agar (malt 
extract omitted) similarly filtered was used because of its greater 
transparency. Unless otherwise specified, all germination tests were 
run in an incubator at 28° C. 


GERMINATION OF THE BASIDIOSPORES. 
The germination of the basidiospores of the species under con- 


sideration presents no features unusual for hyaline hymenomycetous 
spores. All of them swell more or less in the process. The spores 


of Lenzites sepiaria, L. trabea, and Lentinus lepideus swell to very 


little more than the diameter of the germ tube, so that they are not 
very conspicuous in the thalli of the germinated spores (PI. III. 
fig. 1; Pl. IV, fig. 1; Pl. V, fig. 2). Fomes roseus spores swell con- 


siderably (Pl. V, fig. 1), but those of Trametes serialis swell much 


more (PI. IV, fig. 5). These latter spores swell to a large globular 
body of many times the volume of the original spore before the germ 


6 BULLETIN 1053, U. S. DEPARTMENT OF AGRICULTURE. 


tubes are formed, and the spore is always very conspicuous in the 
thallus. The germ tubes of Fomes roseus have been more vacuolate 
than those of the other species. | 
The spores of all species germinate readily upon all nutrient media 
and upon red spruce (PI. V, fig 10, for Lentinus lepideus). In water 
the results were as erratic as those reported by other workers with 
spores of basidiomycetes. The spores germinated in tap water, al- 
though the proportion ranged from less than 1 to 55 per cent in dis- 
tilled water germination took place occasionally (Pl. ITT, fig. 2, for 
Lenzites sepiaria). The rate of germination was usually low, 
although sometimes as high as 50 per cent. Even with fresh spores 
germination could not always be induced in distilled water. 


EFFECT OF TEMPERATURE UPON THE GERMINATION OF THE BASIDIOSPORES. 


In these studies both percentage and rapidity of germination have — 


been noted. It is interesting to know the rate at which these spores 
germinate, but of the two criteria percentage would be likely to give 
the best indication of the effect of various environmental conditions. 
From the point of view of infection of structural timbers, if a large 
percentage of.spores will germinate over a wide range of temperatures 
it makes little difference whether it takes three or four days for 
them to germinate at 10° C. (49° F.) or only 16 hours at the optimum 
rate of germination. The chances for infection, however, are some- 
what greater at the optimum temperatures, because of the somewhat 
larger number of spores capable of germinating. The percentages 
given herewith have no absolute value, either for the individual 
species or for purposes of comparison between species. It is possible 
that spores collected from different fruit bodies of the same species 
of different degrees of maturity, from different climatic conditions, 
and under different conditions of casting might give varying per- 
centage values. It is certain that age is a factor. Hence, that one 
species should give 75 per cent germination at the optimum tempera- 
ture and another only 40 per cent does not mean that the spores of 
the one are inherently more vigorous than those of the other. In 
the data presented germination is taken to consist in a germ tube at 
least as long as the swollen spore. The data for the effect of tem- 
perature upon germination are given in Table 1 and in figure 1. 
For Lenzites sepiaria with certain variations tests showed that 
between 12° and 40° C. (538° and 104° F.) there was little difference 
as to the effect of temperature upon the percentage of germination if 
the time element was disregarded. The optimum for rate of germina- 
tion was between 32° and 36° C. (89° and 97° F.), an optimum 
somewhat lower than that obtained by Falck. At 40° C. (104° F.) 
the results varied with the age of the spores. Those a few months 


FUNGI OF IMPORTANCE IN THE DECAY OF TIMBERS. 7 


old gave only sparing germination, while fresh ones germinated 
about as well as at 36° C. (97° F.) but more slowly. Falck (14, 


80, 


FEF CLEIVT 
Qo g 


FER CENT 
s 


Ml CHONG FER BOHOURS 


16 a? G2 F 
DEGCKLES CENT/IGRADE 


| ‘Fic. 1.—Effect of temperature upon the germination of the basidiospores upon malt agar. 
A, Maximum percentage obtained, disregarding the time element; B, percentage of 
germination in 20 hours; (@, rate of growth of the thalli in 20 hours (shown in 
microns). These values are not to be considered as absolute for any of the species, 
nor are they necessarily comparable species with species, but they represent the values 
obtained with the spores available. 


 ~pp. 98-99) found that they germinated at 42° C. (107° F.) but not 
at 46° C. (115° F.), with most rapid germination at 34° C. ssi F.). 


: 


bil 


8. BULLETIN 1053, U. S. DEPARTMENT OF AGRICULTURE. | 
. 
The lowest temperature tried by him was 10° C. (49° F. ), and the ¥ 
spores germinated at that temperature. } } 


TABLE 1.—Relation of temperature to the germination of basidiospores. 


Germination. 
Species and temperature. : 
oe Taken in— Rate. 
Lenzites Sepiaria (Spores 3 days old): 
Be Ol eee es eee 40 |} 4days........ Germinated in 2 days. 
U5? Co....)5 322 Gee a sinc soee een eke AGH ace COLUM eS oe 14 to 18 » in 20 hours. 
OR er te fee ee ee eee 43 | 24 hours....... 30 to 40 » in 20 hours. 
7 Joa Cn sae aes eae i gs a oN as AR 45 | 20 hours.....-. 105 to 175 w in 20 hours. 
B20 ©. o.oo SER Obs o.cos Soe eee ane eee 42u eet do. ete 210 to 350 uw in 20 hours. 
BG? © k= bcc sobs eee entes UL Re Raa 431%. fu; GO2s o.eeee 180 to 250 » in 20 hours. 
AO? ©. See wbaseeeee, uaaee e oe 40 | 36 hours....... a and beginning of tubes in 36 
ours 
Lenzites trabea (spores fresh) 
2 ia pte, SNS ore a 2 ui saie de lakes 33 | 3 days.........| 12 to 21 » in 20 hours. 
20°. Cisiecuic boc get teee wow sth weerwas 57 34 | 48 hours....... 43 to 73 « in 20 hours. 
2A Otr ss... # ts ssn yore as oe 32 | 36 hours.....-. 90 to 143 w in 20 hours. 
28° C WER SSS haa el ae. . ae 36 | 26 hours....... 160 to 245 » in 20 hours. 
SO? Ci soreee tutes © Se. ee hs i hee ag a 210 to 350 w in 20 hours. ~ 
B29 Cesc etek «a ot ode setae one 37 | 26 hours. ...... 310 to 450 » in 20 hours. 
BOCAS. a:o4 2k Sch ie Ce. 2 Ae OOF. seu GO. Sees ic 175 to 200 uw in 20 hours. 
AOC es hisio Ret tne race hier eter (2). {| 36hours: 5.54.2 Just beginning in 20 hours. 
Trametes Serialis (spores 8 days old) 
FN cee des eine ea 40 | 12 days....... 7 to 32 win 12 days. 
TG. eyes oes elt i Ne vc el eee 39 | 10 days....... 15 to 25 uw in 8 days 
15 See ee sek lem omen ccteee a eee 41}|, 6 days: . 2. ca. 160 to 300 win3 ays. 
71121 OA ee, Snare res fh >! at 415), 42 Hours, oz cit. 31 to 68 » in 20 hours. 
PAs Teel CAE SN NERS We Ne aime oo te |! eT 40 | 24 hours....... 60 to 80 » in 20 hours. 
ZSP Oke et re ES te Ble coh Oy A Ot eo 41th. Se GOs ech e 87 to 125 » in 20 hours. 
Bo) Oe: oscar cele ss oot oe eee a eee donno. ae 210 to 235 » in 20 hours. 
Ore Cie aisle bres ie ke ee UGS PSE 0 dative Just beginning in 20 hours. 
BO MS Sh clas ain Gabonese me Oj} | 3 Gays>2.~- 4.. 
Fomes roseus (spores fresh) 
IO ae delete seats eae eae. aaa 1}) month..2 745 Germination in 1 month. 
BP: Os polices. see cee i ee 15}| O @ayaawacsues Germination in 9 days. 
12° Cu inn oh Sheets = eee 15} | 3 Gays’: 5. aoe Germination in 3 days. 
16° Oaeeet cna ss. ee Se LA 2ce8 GOs ae ' Just beginning in 20 hours. 
ZOMC . jecet dss once edo. ae kee 23)| ZiGayS-.\-2 sa.e 12 to 36 uw in 20 hours. 
24° Cwcvesccuntst et os thot sted 24 | 24 hours....... 57 to 98 » in 20 hours. 
28°C oo oo ee eee BStl. ca G0.).23 2444 98 to 120 w in 20 hours. 
32° Cceckld ghee ee ee ee 2622. Oe aot he2 84 to 121 » in 20 hours. 
362 Cl ee 5 sc PEE ee aes te 1 4 ae at GOna se Just beginning in 20 hours. 
“P40? Cerys. cigs RS | See ee Sa ¥ teu i (eo 
ene. lepideus (spores 7 months 
old): 
O° Cn aA: I ee 40 | 10 days........ Thalli up to 43 w in 23 days. 
LOS Cres oe Lonoke pace (es See ae OO") BABYS... ane 25 to 40 z in 5 days. © 
TOPIC es can See cc oe Ce 54 |.3 days........ 50 to 80» in 5 days. 
BOP Ch cic oe! atc ai ae 60 | 2days........ 43 to 61 » in 20 hours. 
1: teal Cpa “Era ©! My De) IR 75°" 2 HOES. soo: - 133 to 174 » in 20 hours. 
289 CS) saad dee cence we hee 75 | 18 hours....... 150 to 221 » in 20 hours. 
hy al On fe ee te SEM ED ey i 4 16 hours... 124 to 178 » in 20 hours. 
36 oC Os 503.. oie die. es re eee 6 to 257] 24 hours: . ese 42 to 60 » in 20 hours. 
ak OF pate I. eae ac They eae or on when Oflcce. 2.2 eee Just beginning in 20 hours. 


@ Less than 1 per cent. 


The basidiospores of Lenzites trabea germinated in small per- 
centages at 40° C. (104° F.), at high percentages from 24° to 32° C. 
(75° to 89° F.), and most mapidi between 28° and 32° C (82° and 
89° F.). 

The spores of 7’rametes serialis germinated at the lowest tem- 
perature tried, 3° C. (36° F.), but not at 40° C. (104° F.). The gen- 
eral optimum for percentage was between 20° and 32° C. (68° and 
89° F.), with the most rapid germination between 30° and” 32° C.a 
(86° and 89° F.). ) 


FUNGI OF IMPORTANCE IN THE DECAY OF TIMBERS. 9 


Fomes roseus spores germinated most rapidly between 28° and 32° 
C. (82° and 89° F.), while the, percentage was highest between 24°° 
and 32° C. (75° and 89° F.). 

For Lentinus lepideus the largest percentage of germination was 
_ between 25° and 28° C. (76° and 82° F.), although 40 per cent ger- 
minated in 16 hours at both 20° and 32° C. (68° ‘and 89° F.). The 
percentage for the lower temperatures down to 5° C. (40° F.) was 
40 to 50 per cent. These spores germinated in 10 hours at 28° C. 
(82° F.) and in 18 to 20 hours at 24° C. (75° F.). 

_ Falck (16, p. 258) has suggested that the percentage optimum for 
germination of basidiospores is to a certain extent a matter of 
simultaneous germination, and that as the optimum is approached 
there is a greater number of simultaneously germinating spores. 
Inasmuch as all the spores do not germinate at the same time, par- 
ticularly at the lower temperatures, care should be taken to give 
the viable spores opportunity to germinate. According to Falck, 
the more favorably situated spores germinate first, but there is also 
the possibility that the less favorable temperatures affect the proto- 
plasm of the individual spores differently and thus cause differ- 
ences in rapidity of germination. In the case of Lentinus lepideus 
(Table 1) at 5° C. only a small percentage had germinated in 5 
days, 30 per cent in 8 days, and 40 per cent in 10 days. Care must 
be taken also that the percentage counts are not made at intervals 
too great to keep track of what is going on at the lower tempera- 
_ tures. Whereas basidiospores of L. /epideuws germinated 30 per cent 
in 8 days and 40 per cent in 10 days at 5° C., in 23 days in the same 
set of duplicate hanging drops only 22 per cent of living thalli could 
_ be counted. The explanation seems to be that of the 40 per cent 
which had germinated, a certain number of the germinated spores 
could not stand the low temperature and had died and become in- 
visible on the agar substrate. 


EFFECT OF LIGHT UPON THE GERMINATION OF THE BASIDIOSPORES. 


Hoffmann (2/7, p. 32) found that spores of Agaricus campestris 
germinated sooner in the light than in the dark and that bright sun- 
light did not hurt the spores of several imperfect fungi and some 
rusts. Ferguson (19, p. 21) found, however, that the spores of 
Agaricus campestris would not germinate in direct sunlight or in 
diffused light in four weeks, even under the special’ conditions fur- 
_ nished by her for the germination of these refractory spores. In the 
experiments by Buller (8, pp. 24-26) spores of Daedalea unicolor 
and Schizophyllum commune germinated after exposure to direct 
sunlight for periods up to eight hours, but the germination of these 
was slower than of those kept in the dark, and the percentage of 

82278 — 2 


10 BULLETIN 1053, U. S. DEPARTMENT OF AGRICULTURE. 


germination was lower. In three days the mycelium from the spores _ 
kept in the dark was more advanced than that from the spores ex- { 
posed to the sunlight. Rhoads (47, p. 66) noted no difference in the © 
time required for the germination of the spores of Polyporus parga- | 
menus in the presence or absence of diffused light. | 

The writer tested the action of both diffused light and direct sun- 
light upon dry spore prints for a possible killing effect and upon 
spores on agar during germination for a possible inhibiting effect. 
Duplicate spore prints upon slides or agar plates with spores for 
germination were placed side by side in the light, supported upon 
a nonconducting frame, with one of the pair inclosed in a box made 
light-tight and yet allowing for ventilation, in order to prevent the — 
heating of the slides or Petri dishes. Experiments upon the effect 
of diffused light acting during germination were started in the early 
morning and allowed to run until the next night, in order to have 
the spores under the influence of light while starting to germinate 
and to obtain the maximum amount of daylight. 

It was found that two days of diffused light in an east window 
during the winter had no appreciable effect upon the percentage of 
germination or upon the rapidity of germination, although it hin- 
dered the subsequent growth of the thalli somewhat. 

It was found also that diffused light acting upon dry spore prints 
for 10 days had no appreciable effect on the viability of the spores. | 
Direct sunlight acting upon the basidiospores upon agar inhibited 

germination during exposure, as compared with controls. Spores 
exposed to direct sunlight for one day would germinate upon being ~ 
set aside in the dark, but those exposed for two days showed little 
or no germination. 

The tests on the killing effect of direct May and June sunhlitlet 
upon dry spores were carried on chiefly with the basidiospores of 
Lenzites sepiaria and L. trabea, with two tests on the spores of 
Trametes serialis and Lentinus lepideus. When the tests were prop- 
erly checked so as to obviate as far as possible the effect of atmos- 
pheric conditions, the results were as consistent as could be expected. 

In general, it was found that one day of exposure did not affect 
the viability of the spores materially. An exposure of two days 
usually reduced the percentage of germination considerably, some- 
times entirely, while three days’ exposure usually killed most of the 
spores. Only those tests were considered in which the control slides 
showed unreduced germination at the end of the test, for it was 
found, as will be shown later, that certain atmospheric conditions 
greatly reduced the viability of the spores. 

Two experiments were tried to see if the germ tubes showed any — 
phototropic reactions. The slides of Van Tiegham cells were placed © 


pO ee - 


Bi ten a el 


oat ee 


FUNGI OF IMPORTANCE IN THE DECAY OF TIMBERS. 11 


in a photographic plate box with a slit 5 millimeters wide cut in one 


of the narrow sides. The box was set up with the slides inside, the 


slit toward an east window. In the first test the cells were inocu- 
lated at night and examined in 24 hours. In the second the inocu- 
lations were made in the morning and examined in 24 hours. In 
neither set did the germ tubes of any of the four species, Lenzites 
sepiaria, L. trabea, Trametes serialis, Lentinus lepideus, show any 
phototropic response. The tubes pushed out of the ends of the 
swollen spores as usual, and their subsequent course was as irregular 
as in the dark or in diffused light, where checks were placed. 


RETENTION OF THE VIABILITY OF THE BASIDIOSPORES. 


Falck (15, pp. 99-100) expressed the opinion that in nature the 


length of time the spores of wood-destroying fungi could retain 
‘their viability was a matter of little moment, inasmuch as most of 


them had the ability at least to hold over the longest period of 
drought. Rumbold (49, p. 102) found that 0.25 per cent of the 
spores of Coniophora cerebella germinated after one year and six 
months under laboratory conditions. Falck (15, p. 100) reported 
that the spores of Lenzites sepiaria 6 months old germinated like 
fresh spores, but from that time there was a steady decrease in the 
percentage of germination. In a year and seven months only a very 
few germinated, and none in two years. The spores of Merulius 
lacrymans he found (16, p. 234) to be longer lived. Spores 1 year 
old germinated normally; after three years 25 per cent germinated ; 
and after five or six years spores sprayed with 2 per cent malic 
acid, dried immediately, and then put in a moist chamber at 15° 
C. gave some germination. Rhoads (47, p. 70) showed that the 
spores of Polyporus pargamenus kept on waxed paper in a desk 
in a warm room remained viable for 10 months, but not for 12. 
At the end of that time there was swelling, but no germination. 

The question as to the maximum period of retention of vitality re- 
solves itself into how best to preserve spores under laboratory condi- 
tions. It has been shown by Falck (24, p. 100) and Moller (36, p. 38) 
that spores are best preserved when taken dry and kept dry, and that 
spores in a moist atmosphere soon deteriorate. Thick prints also 
undoubtedly keep better than thin ones. Just what combination 
of dryness and temperature is more favorable for prolonging the 
life of the spores is not certain. The writer has kept spores best in 
an ice box, where the temperature was found to be 12° to 15° C. 
and the relative humidity 40 to 45 per cent. A very humid at- 
mosphere is harmful, as are also very dry conditions at higher tem- 
peratures. Whether very dry and cool conditions would be better 
than a moderate amount of moisture in the air at the same tem- 
perature is not known. 


12 BULLETIN 1053, U. S. DEPARTMENT OF AGRICULTURE. 


The longest periods during which any spores of the species 
studied have given germination are shown in Table 2. 


TABLE 2.—Maximum period of retention of viability of the basidiospores of 


Lenzites sepiaria, Lenz 


Lentinus lepideus. 


ites trabea, Trametes serialis, Fomes roseus, .and 


Period of retention of viability. 


Species wr poorer’ of sporo Germination. 
Daten Spores germinated 
i after— 
Lenzites sepiaria: 
. eo Wis., Novem- | Apr. 13, 1918, to Feb. 10, 1921.| 2 years 10 months @....| 25 per cent. 
er, 1917. 
L. trabea: 
Cotton mill, Centerville, | February, 1920,to February,| 1 year @............... 60 per cent. 
R.I., February, 1920. 1921. 
Trametes serialis: 
Madison, Wis., Novem- | November, 1916, to Febru- | 4 years 3 months 2@..... 2 per cent. 
ber, 1916, ary, 1921. 
Fomes roseus: 
Wisconsin, June, 1917, | June, 1917, to December, | 18 months ?........... Few in thousands. 
on tamarack (Larix). 1918. 
Minnesota, June, 1919, on | June, 1919, to Feb. 10, 1921...| 1 year 8 months @...... Less than 1 per 
Prunus. cent. 
Lentinus lepideus: 
Cotton mill, New Bed- | July 5, 1918, to Feb. 10, 1921..| 2 years 7 months °..... Do. 


ford, Mass., July 5, 1918. 


a These figures refer to the last tests; further tests may show that these spores survived longer periods. 
> These spores gave no germination in 20 months. 


VIABILITY OF BASIDIOSPORES DRIED AT DIFFERENT TEMPERATURES. 


Because of the lack of sufficient quantities of basidiospores, tests 
upon the effect of drying are neither complete nor entirely satisfac- 
tory, because only one series has been conducted. It is to be expected 
that the age of the spores will make some difference in their resistance 
to drying and that, as pointed out previously, individual casts of 
spores may vary, hence the tests here reported are only indicative. 
For example, it will be noted (Table 3) that spores of Trametes 
serialis 2 years old succumbed sooner at 28° C, (82° F.) than at 32° 
©. (89° \F.).: 

At 28° and 32° C. the spores of Trametes serialis and Lentinus 
lepideus of the ages given ceased to germinate after an exposure of 
about 10 weeks to dry incubator conditions. At 36° C. (97° F.) it 
took about a month to kill all or most of the spores. 

At 40° C. (104° F.) it will be noted (Table 4) that in one week 
there was a decided drop in the percentage of germination of the 
spores of the three species tested. Those of Yomes roseus did not 
survive one week at 40° C. In two months, however, the spores of 
Lenzites sepiaria were not all killed, nor those of Trametes serialis 
in six weeks. These spores were fresh, while those in the tests at 
36° C. were not absolutely fresh. 


FUNGI OF IMPORTANCE IN THE DECAY OF TIMBERS. 13 


Taste 3.—Effect of drying at different temperatures wpon the germination of 
basidiospores of Trametes serialis and Lentinus lepideus. 


Trametes serialis (spores 2] Lentinus lepideus (spores 5 


years old). months old). 
Drying temperature. Germination Germination 
(per cent). (per cent). 
Period. Period. p 
Dried. | Check. Dried, | Check. 
Beginning..... 50 50 | Beginning..... 50 50 
1 eer BUEN -_ 430 50 | 2 weeks ee 51 50 
2° weeks: ..ct- 18 50 | 4 weeks....... 24 49 
At 28° C. (82° F.)........------------- A weeks. 5 4... 1 50 | 6 weeks........ 28 50 
Oweekstisy &S 0 50 | 8 weeks....... 14 52 
BERENS indie ay ese bo SSC en 94 weeks.....- 0 50 
Beginning..... 50 52 | Beginning..... 50 50 
1 ed Ree eae 1 48 | 2 nee Ftp 53 49 
' ZiWweeks: Sa.) 2. 1 51 | 4 weeks....... 22 48 
At 32° C, (89° F.)....-..-- 22-22-22 e es 4 weeks. ...... 1 51 | 6 weeks....... 17 51 
- f} weeks.....-. 1 50'| 8 weeks.....-- 5 42 
94 weeks...... 0 0 | 93 weeks...... 0 | 51 
| 


Trametes serialis (spores 10 Lentinus lepideus (spores 7 


days old). months old). 
PER. ret rd Bacinning nis oe He | a 

° ° YSsors 2 | 45 | 10 days........ 2 
At 36°C. (97° F.)....--------- 2-65 ---- 18 days........ 1 20] 18days........ 3 | 20 
28 days 0 | 20 1 28 dayseise.2- ei" () ' 20 


- 1 Less than 1 per cent. 


TABLE 4.—Effect of drying basidiospores of Lenzites sepiaria, Trametes serialis, 
and Fomes roseus at 40° C. 


Lenzites sepiaria (spores Trametes serialis (spores Fomes roseus (spores 5 
fresh). fresh). months old). 
Drying Germination ‘| Germinati inati 
ation Germination 
temperature. (per cent). (per cent). (per cent). 
Period. Period. | Period. 
Dried. | Check. ; Dried. | Check. Dried. | Check. 
Beginning. 38 38 | Beginning. 76 75 | Beginning. 38 30 
40°C (104° F ) 1 week.... 13 39 | 1 week.... 14 75 | 1 week.... 0 26 
‘ i =a\)20 Gays..... 8 39 | 6 weeks ... 7 (MBs eS al Se a RA 
2 months.. 3 ap | 232852 2. CREED 2 Chak) oe ORR E Ake s Seat oe SSC 


EFFECT OF ALTERNATE WETTING AND DRYING UPON THE VIABILITY OF THE 
BASIDIOSPORES, 


In removing spores from a spore cast on a glass slide, a large 
number of the spores dislodged from the slide by the water are left 
behind. From the point of view of economy of material the ques- 
tion naturally arose as to whether or not these spores wet once and 
allowed to dry out again were capable of normal germination. A 
number of tests made upon different lots of spores of varying ages 
from fresh ones to those a few weeks old seem to show that alternate 
wetting and drying reduce the percentage of viable spores. In one 


14 BULLETIN 1053, U. S. DEPARTMENT OF AGRICULTURE. 


case the reduction in the percentage of germination was only from 
48 to 37 per cent. In others, it was from 70 to 20 or 30 per cent. In 
most of the tests, however, the reduction was more pronounced, re- 
sulting in no germination or only 2 to 5 per cent. The lack of uni- 
formity in results is probably to be explained by differences in the 
condition of the spores, length of time they pemalnes wet, and time 
taken to dry. 

It was found in the preliminary experiments of the effect of 
light upon germination that spore prints left out of doors over night, 
even though protected from falling water, lost their viability after 
one or two nights and days. Similar spores retained their normal ° 
viability, however, when protected over night in a closed desiccator 
(without drying chemical). Spores of all five fungi studies behaved 
in the same manner. The explanation is probably to be found in 
the diurnal changes of atmospheric humidity. 


OBSERVATIONS ON THE CASTING OF THE BASIDIOSPORES. 


Buller (8, p. 111) has shown that fruit bodies of Lenzttes sepiaria 
can be revived and made to cast spores after four months of drying. 
Falck (75, p. 66) revived them after one year and nine months of 
drying. The writer collected some sporophores of this plant from 
prostrate white pine in Wisconsin in June, 1919. The weather had 
been sufficiently moist to allow the formation of an abundance of 
sporophores and it is not known how long any of them had been — 
casting spores. The collections were taken inside and left for a day. 
They were then moistened over night and placed upon glass slides 
the next day for spore casting. At night the prints were collected 
and the sporophores allowed to dry on a table in the room until the 
night of the second day following, when they were again moistened 
for another cast the next day. With this rotation of 48 hours of 
drying in the room, 12 hours of wetting, and then 12 hours of cast- 
ing, spore prints were obtained six times. The seventh time the 
sporophores failed to produce visible prints., ‘Several sporophores 
collected when frozen in November, 1919, and then kept in an ice 
box for one month were treated in a similar manner in the labora- 
tory. Visible casts were obtained four or five times from single 
sporophores, even through the summer of 1920. 

Sporophores of Lenzites sepiaria kept in the laboratory were re- 
vived after 15 months and usable prints obtained, but the same ones 
would not revive after two years. Sporophores which had over- 
wintered out of doors during 1919-20 (one set in Providence, R. L., 
and the other in northern Vermont) were made to cast spores a 
early March and April, 1920. 

Sporophores of Lenzttes trabea have been revived after six to nine 
months, but repeated castings have not been obtained from the same 


FUNGI OF IMPORTANCE IN THE DECAY OF TIMBERS. 15 


sporophores. Sporophores collected near Providence which had 
overwintered were made to cast spores abundantly in April, 1920. 
The fruit bodies of 7rametes serialis studied were those, already 


q referred to, which were formed in the fungus pit in the forest-path- 


ee ee ee 


ology greenhouse at Madison, Wis. This fungus fruited on the tim- 


bers each fall from 1916 to 1919. It is not known whether fruiting 
occurred at other times. The sporophores were few in number and 
the total hymenial surface never exceeded 150 square centimeters. 
These small fruit bodies, however, liberated large numbers of spores. 
Figure 1 of Plate VI shows visible prints from one small one during 
two or three days on a vertical surface where the hymenial surface 
was not large, and it is likely that only a small part of the spores 
cast were caught on the surfaces shown. In a single day resupinate 
sporophores cast thick crusts of spores on glass slides and continued 
to do so for several days. All of the basidiospores of Z’rametes 
serialis used in this work for three winters came from heavy casts 


- made in the fall of 1916. Three fruit bodies formed in November, 


1919, were kept under observation in order to obtain some idea as 


to the length of the casting period. Fruiting was first noted on 


November 18 and casting had already begun. It continued for 15 
consecutive days. 
These fruiting bodies of 7'rametes serialis were formed in the dark. 


The largest one was kept in the dark for the whole period of 15 


days, and the two smaller ones were put in a moist chamber in the 


light in the laboratory. Spores were cast abundantly in both places. 
_ On the fifteenth day the sporophores began to turn brown at the 
_ edges and shrivel up, although in an atmosphere practically satu- 
rated, and these parts became attacked by molds. On the next day 


the browning and shriveling had proceeded farther and the molds 


had spread. The simultaneous cessation of casting and encroachment 


of molds was striking, as was the absence of molds on the delicate 


_hymenia during the 15 days of sporulation under very humid con- 


ditions. —The same phenomenon was observed in the tests on the cast- 


- ing of spores by Lenzites sepiaria, as molds did not make their ap- 


pearance until after the sporophores had ceased to cast spores. The 
spent fruit bodies of 7'rametes serialis left in the fungus pit soon 
disappeared. When dried artificially, they became very thin, fragile, 
and distorted, but in the pit they disintegrated through attack by 
molds and pUnctierption by sow bugs. 

The writer has never succeeded in obtaining basidiospores from 


_the perennial form of Pomes roseus.. From the annual form spores 
_ are usually cast sparingly. In the laboratory visible prints have been 
obtained only occasionally. Attempts to obtain prints out of doors 
were made at Crawfords, N. H., in September, 1919, during a pro- 


16 BULLETIN 1053, U. S. DEPARTMENT OF AGRICULTURE. 


tracted period of moist weather, but efforts with many sporophores 
at different locations resulted in little success. Sporophores of the 
annual form of F’. roseus were revived to cast a few spores after 20 
months in the laboratory. 

No data are at hand relative to the length of the spore- casting 
period of Lentinus lepideus. Sporophores of this fungus will some- 
times revive in moist atmosphere after having been kept dry a few 
months (six months at least) and will cast spores. The chief diffi- 
culty in obtaining prints is that molds growing on the fleshy pilei 
contaminate them. A single fruit body will liberate a large number 
of spores in a short time. A large one, about 10 centimeters in 
diameter, will overnight cover an area half the size of a sheet of 
paper of letter size with a heavy layer of spores. Attempts to revive 


sporophores of this fungus 16 and 19 months old were unsuccessful. — 


Since these fungi fruit within mills (and at least three of them 
(Lenzites sepiaria, L. trabea, and Lentinus lepideus) are known to 
cast spores in abundance under mill conditions) it is probable that 
basidiospores play an important part in the dissemination of the 
fungi therein. 


OBSERVATIONS ON THE DISSEMINATION OF THE BASIDIOSPORES OF TRAMETES 
SERIALIS. 


The works of Falck (74) and Buller (8) have given us some infor- — 
mation on the dissemination of the basidiospores of hymenomycetous 
fungi. Falck showed how the spores were dispersed uniformly — 
within closed glass vessels, even to some height within narrow con- — 
tainers. His method of determining the dissemination was by col- 
lecting spore deposits upon shelves or ledges at various locations 
throughout the chamber. He showed with what ease currents of air, 
invisible and imperceptible, caused by temperature changes could 
transport the basidiospores. He found that insulated fruit bodies 
in insulated glass chambers have a higher temperature than the 
surrounding atmosphere and formulated a theory that the ability 
to produce this higher temperature was an adaptation serving to 
warm the layers of air beneath the pilei for the purpose of producing 
convection currents to disseminate the spores. He went farther and 
maintained that the thickened pilei of fleshy hymenomycetes were 
symbiotic adaptations providing food for maggots, whose respiration 
produces’ heat. Buller (&) demonstrated basidiospore dissemination 
by means of his beam-of-light method. His work was more com- 
prehensive than Falck’s, and while agreeing with Falck’s general 
conclusions as to the ease of dissemination of these spores, he could 
not regard it as demonstrated that the heat of the pileus was of 
material help in disseminating spores in the open. He maintained ~ 
that the convection currents naturally present at all times out of 


| 


FUNGI OF IMPORTANCE IN THE DECAY OF TIMBERS. 17 


doors were the important agents and that any convection currents 
formed by the heat of the pileus would be swamped by the natural 
currents under most conditions. Falck in a later work (16, pp. 226- 
227) demonstrated how the spores of Merulius lacrymans are scat- 
tered throughout buildings. He found that a fruit body off in a 
corner in a church spread spores throughout the edifice and that. 
spores from fruit bodies in a cellar where the temperature was a little 
higher than that of the rest of the house were carried by air currents 
to various places in the house. He caught them on glass slides under 
a bed on a first floor and at places on the second floor. Even a closed 
door did not keep them out. 

The writer had no opportunity to make extended observations on 
the dissemination of basidiospores, but several instances came to 
hand which corroborated in a small way the observations and con- 
clusions of the above-mentioned authors. Certain observations pre- 
sented here have to do with the fruiting of 7rametes serialis in the 
fungus pit at Madison, Wis., already referred to. Two fruit bodies 
of this fungus appeared toward the last of January, 1919. One of 
them grew at the end of the under side of a horizontal timber. On 
entering the pit one day it was noticed that the transverse face and 
a part of the upper surface of the beam were powdered white with — 
a deposit of the spores from the fruit body below (Pl. VI, fig. 1). 
Several similar deposits were noted in November, 1919, when several 


fruit bodies appeared, most of them on the under side or on the end 


of another beam. Here were cases in which the spores had been swept 
directly upward, as if carried by a strong draft from below. But 
just. how there could be strong drafts it is difficult to understand. 
The pit is sunk 4 feet in the greenhouse floor, walled with concrete, 
and has a dirt floor and well-fitting covers. There is very little like- 


‘lihood of air currents from eutside. Glass slides placed beneath the 


sporophore gathered no spores, but slides placed at points throughout 
the pit, even at the top near the covers, collected enough spores to be 
located under the microscope. 

In mills, however, the dissemination of spores is not dependent 
upon such imperceptible air movements, for considerable air currents 
are produced by rapidly moving machinery, sprays from humidifiers, 
and steam pipes poorly arranged. These currents become of great 
importance in distributing spores which may be cast into the air by 
fruit bodies upon the roof planks. 

In the fungus pit on two occasions the opportunity presented 
itself for observing to what extent insects and other animals may 
under certain conditions disseminate wood-destroying fungi. There 
is little literature bearing upon this phase of the subject. One 
occasionally meets with references to the connection between wood 


$2278 —22——3 


18 BULLETIN 1053, U. S. DEPARTMENT OF AGRICULTURE. 


decays and insect burrows (cf. Spaulding, 56; 57, p. 115), but little 
is known as to how great an extent insects are responsible for carry- 


ing the spores of these fungi and starting infections. Hubbard (28, - 


p. 251) reports that several bark insects have been found within the 
veil of Cryptoporus volvatus and suggests that such insects may 
carry the spores from fruit bodies into direct contact with the inner 
layers of bark of uninfected trees. One beetle (/puraea monogama 
Crotch) he found (p. 253) always coated with a thick layer of the 
spores. Zeller (63, p. 124) has made similar observations in connec- 
tion with the same fungus. The common occurrence of fungus gnats, 


mites, springtails, and slugs upon hymenia has been noted by several - 


(Buller 8, pp. 19, 20, 23, 96). 

The fruit bodies of 7’vrametes serialis mentioned above appeared at 
a time following a thaw when a considerable quantity of water seeped 
into the fungus pit from the earth below, making a damp chamber of 
the whole pit. The dampness caused an abundance of spores to be 
cast. The beams bearing the sporophores were so situated that they 
were about 1 centimeter above a piece of plank. It was so moist in 
this space that water had collected on the plank under the sporophore 
and this water was full of basidiospores. With the advent of moist 
conditions within the pit also came sow bugs. ‘They infested the 
woody material and were particularly abundant on and around the 
fruit bodies, even wallowing in the water full of basidiospores. A 
number of these animals, with small spiders and springtails asso- 
ciated with them, were collected and examined for spores and, of 
course, were found to bear great quantities of them. All animals 
collected on that particular beam had spores in varying quantities 
on their legs, antenns, and sete, and many of them, particularly the 
sow bugs, had a large number of spores upon their backs where they 
had fallen directly from the sporophore. A photomicrograph (PI. 
VI, fig. 2) shows the immense number of spores on the appendages of 
sow bugs taken from the water beneath the fruit bodies. Sow bugs 
caught covered with spores as just described were transferred to 
flasks of sterilized wood blocks and incubated. The blocks became 
somewhat contaminated with Penicillium, as might be expected, 
although not heavily, but a hymenomycetous growth was noted in the 
flasks as well. After several months the blocks were removed and 
found to be decayed, showing that the dissemination of wood- 
destroying fungi by means of arthropodous animals is possible. 

The point to be made in connection with the relation of sow bugs 
to the possible dissemination of basidiospores within buildings is 
that the fruiting of these fungi and the presence of the sow bugs 
are often tied up with moisture conditions. Certain fungi will fruit 


in moist places, especially near the earth and in small inclosed places 


: 
: 
, 
, 
, 
. 


Sl SS ee. 


FUNGI OF IMPORTANCE IN THE DECAY OF TIMBERS. 19 


where damp chamber conditions prevail, and the sow bugs are pres- 
ent in the same environment, particularly where the light is weak. 
Such conditions are common in and around many structures. 

Springtails also are of common occurrence in the fungus pit, and 
are found commonly on the moist decayed wood. It is possible that 
other insects which inhabit buildings, such as cockroaches and spi- 
ders, may take some part in disseminating basidiospores. In mills 
there is the possibility that insects may assist in the dissemination 
of these fungi as much as they assist in ordinary cases out of doors. 
Insects of several unidentified species feed upon the fruit bodies of 
both Lentinus lepideus and Trametes serialis to such an extent that 
sound specimens can be obtained only within a short time after for- 
mation. Insects coming in contact with fruiting surfaces can not 
fail to carry away spores, because of the nature of their appendages 
and the stickiness of the spores, as has been demonstrated. 


MYCELIUM. 


PREPARATION OF CULTURES. 


The cultures of the five fungi used in the physiological studies 
were derived from single spores of the collections already noted. 
The method of obtaining the single-spore cultures was essentially 
that of Keitt (27). The basidiospores were allowed to swell, and 
before the germ tubes developed peyera were picked out and trans- 
ferred to tubes of malt agar. 


MACROSCOPIC APPEARANCE OF CULTURES GROWN AT ROOM TEMPERATURE. 


In cultures of Lenzites sepiaria on malt agar no aerial growth 
is seen until a day or two after the submerged mycelium has ap- 
peared, and in some cases, especially in the dark, very little aerial 
mycelium is in evidence at all. The aerial growth (secondary my- 
celium) is very scant, at first white, and breaks up almost entirely 
into oidia, which give the surface of the culture a more or less 
damp-powdery appearance. In three weeks to a month this super- 
ficial growth may become avellaneous to wood brown.’ The writer 
has seldom seen anything but this secondary mycelium which breaks 
up into oidia, but occasionally a tertiary growth will appear over 
the oidia-forming mycelium, forming a more matted or patchy 
growth. At optimum temperature (30° to 34° C.) a 10-centimeter 
Petri dish is covered in about eight days. On wood the superficial 
growth is equally scant. The surfaces of the blocks become spar- 
ingly flecked with a white, coarse powdery growth, which is found 


* All colors referred to are those in Ridgway’s ‘Color Standards and Color Nomen- 
clature.”? 


20 BULLETIN 10538, U. S. DEPARTMENT OF AGRICULTURE, 


to consist for the most part of oidia, with a moderate amount of 
strand development on the surfaces and between the blocks. This 
growth on wood may turn wood brown in its later stages of devel- 
opment. No fruit-body formation has been observed in either the 
agar or wood cultures. 

On malt agar the first growth of Lenzites trabea (the secondary 
mycelium) is white and has the same damp- -powdery appearance, 
due to the pressure of oidia, as L. sepiaria. This secondary myce- 
lium is much more abundant than that of L. sepiaria, however. In 
ten days or more this growth is followed by the tertiary mycelium, 
which begins in patches and later more or less entirely overgrows 
,the secondary mycelium. It is thick, fluffy woolly, more or less 
bunchy, in color pale yellow-orange to light ochraceous buff, and 
shows no sign of the powdery appearance, because it forms no oidia. 
It forms large yellow-orange masses of mycelium in the upper ends 
of agar slants and fruits quite abundantly after a month or more. 
On wood the first mycelium is white, and no oidia formation has 
been noted. The mycelial growth is more abundant than that of 
Lenzites sepiaria, more bunchy and patchy, and becomes colored as 
noted upon malt agar. 

Trametes serialis on malt agar makes a white cottony growth, 
slightly patchy at times, and occasionally may be more fluffy and 
thick near the peeiphary of the culture. In later stages there is a 
tendency toward a snuff-brown color. In tubes the superficial myce- 
lium forms a fluffy white mass, which grows up the walls. The upper 
end of the slant becomes sepia or auburn with age and occasionally 
develops a thick brown mass of mycelium which forms pores. On 
wood this fungus at first makes a thick growth over the individual 
blocks with some strand formation and then continues to form an 
abundance of white mycelium which fills the interstices between the 
blocks, finally covering the wood with a thick snow-white mass in 
three or four months, This mycelial growth may become more or 
less suffused with a brownish tint and may form a brown exudate 
in places, When the blocks are removed from the flasks after six © 
months or more, they are covered with a thick white mass having 
a consistency of cream cheese. Abortive irpiciform fruit bodies, — 
having plates instead of normal pores, are formed after six months 
in these block culture flasks and occasionally resupinate poroid forms 
develop upon the slanting sides of the flasks, connected with the 
mycelial mass by thick strands. 

Single-spore cultures of Homes roseus form a- white cottony 
growth on malt agar, thicker and more compact than those of 
Trametes serialis, having the appearance of washed cotton flannel. 
They are white in color when fresh, becoming avellaneous or snuff | 


FUNGI OF IMPORTANCE IN THE DECAY OF TIMBERS. 21 


brown with age in patches and at the upper ends of slants. The 
writer’s single-spore cultures from the annual form of the fungus 
upon coniferous hosts have only rarely developed any pink color, 
and then only a pale pinkish cast after 18 to 20 months of trans- 
ferring, Single-spore cultures from the annual form upon Prunus 
sp. have developed colors from pink to Mars brown in patches or 
streaks. Tissue cultures from the annual form upon spruce have 
taken on only a pale-pink color, but similar cultures from the per- 
ennial form have developed a thick mat of mycelium old rose to 
Mars brown. The same cultures, with the exception of the single- 
spore cultures used in these experiments, have varied from transfer 
to transfer both in color and character of growth. This growth may 
be described as above, a thick mat, as in the tissue culture of the 
perennial form, or varying, thick, irregular growths, as found in 
other cultures. Layers of pores have been formed in the cultures 
derived from sporophores, but not as yet in the single-spore cultures. 
The culture of Yomes roseus used by the writer in this work is !a 
relatively slow grower, covering a 10-centimeter Petri dish in 12 
days at its optimum temperature. 

On wood the slowly growing mycelium of the culture used eventu- 
ally completely covers the blocks, but the growth is very thin, not 
at all fluffy or abundant, and the interstices between the blocks are 
not filled as they are by Zvametes serialis or Lentinus lepideus. 
There is no great mass of superficial mycelium formed. The growth 
upon the blocks has the same washed-flannel appearance as have the 
_ agar-plate cultures, has abundant strand formation, and may become © 
chestnut to argus brown in places in nine months or more. 

Young cultures of Lentinus lepideus on agar are light cottony or 
felty, with more or less tendency to the formation of thin and thick 
zones of aerial mycelium. The inoculum turns snuff brown in two 
weeks, and the rest of the aerial growth turns buckthorn brown to 
cinnamon brown as it grows older, perhaps only in patches. In one 
month the culture may develop numerous umbonate or tubercular 
cushions of mycelium, which vary from white to Prout’s brown, 
exude droplets of a dark color, and have a distinct aromatic odor. 
They are apparently either primordia of sporophores or abortive 
fruit bodies. No well-formed sporophores have developed in the 
writer’s plate cultures. Strand formation is quite pronounced in 
four to six weeks. In tubes the cultures are much the same as the 
plate cultures. In the wood cultures in flasks the mycelial growth 
is abundant, covering the blocks, at first white and later becoming 
buckthorn brown or bister in patches, forming abortive fruit bodies 
in six to nine months. Clusters of long thin crystals are formed 


22, BULLETIN 1053, U. S. DEPARTMENT OF AGRICULTURE, 


quite abundantly throughout the flasks. The mycelium of Lentinus 
lemdeus covers the individual blocks with a bunchy, uneven growth, 
while that of 7rametes serialis forms a thick, even growth over the 
whole mass of blocks. Yet the mycelium of the former fungus binds 
the blocks quite solidly together, so that it takes some little effort 
either to remove individual blocks from the flask or to loosen the 
mass for emptying the flask, while the more pronounced mycelial 
growth of Trametes serialis does not have such a binding effect. The 
aromatic odor mentioned is much more pronounced in the flask block 


cultures; the other four fungi here studied do not produce such an 
odor. 


MICROSCOPIC CHARACTERS OF THE MYCELIA ON MALT AGAR. 


Lenzites sepiaria: 
Secondary mycelium— 

Submerged. 

Colorless, avellaneous in mass; 1.5 to 4.6 w’*, most 2.5 to 3.2 p; 
septa fairly abundant; branching not abundant; clamps not observed ; 
chlamydospores and oidia found occasionally on submerged mycelium, 
the latter chiefly in agar drop cultures. : 

Aerial. 

Colorless; chiefly short, branched hyphze which break up more or 
less completely to oidia; size same as submerged; septa fairly 
abundant; no clamps observed. Oidia colorless, mostly ellipsoid- 
oblong, occasionally ellipsoid, ovoid, globose, pyriform, or clavate, 
occasionally septate; terminal oidia usually clavate; 2.5 to 3 u X 
4 to 35 uw; helicoid hyphe present, but not abundant. 

Tertiary mycelium (aerial)— 

Seldom noted in the writer’s single-spore cultures. In cultures from 
sporophores, more abundant; long, stiff, hairlike, sparingly branched, 
septa not abundant, clamps at septa. 

Lenzites trabea: 
Secondary mycelium— 

Submerged. 

Colorless; 1.5 to 8 uw; irregular; branching, clamps, and septa 
abundant; chlamydospores much less abundant than the oidia, thin 
or thick walled, terminal or intercalary, ovoid to globoid, 6 to 8 X 
8 to 18 pu. 

Aerial. 

Colorless; 1.5 to 3 uw; branching common, usually at right angles; 
clamps and septa fairly abundant; oidia abundant, mostly cylindrical 
to ellipsoid-oblong, terminal ones ovoid to pyriform and clavate or 
even globoid, 2 to 8 X 6 to 24 uw, mostly about 5 X 10 uw. 

Tertiary mycelium (aerial)— 

Colorless, slightly yellowish in mass; long, straight, and stiff; branch- 
ing and septa not abundant; clamps fairly abundant; no oidia or 
chlamydospores observed. 


a 


4The figures in these descriptions refer to the range of measurements observed during 
ordinary examination. 


FUNGI OF IMPORTANCE IN THE DECAY OF TIMBERS. 23, 
Trametes serialis: F 
Secondary mycelium— 

Submerged. 4 

Colorless; 3.3 to 6.3 mu; septa relatively few, far apart in some 
hyphe, close together in others; clamps very few and small; branch- 
ing more frequent than in aerial vegetative mycelium, may begin as 
close to growing tip as 150 yu, but usually farther back; contents of 
young hyphe homogeneous, with occasional angular crystals; chlamy- 
dospores fairly common, varying more or less with age of culture, 
very abundant in old cultures; colorless, ellipsoid, fairly thick walled, 
4.5 to 10X7 to 21 uw, occurring intercalarily. 

Aerial. 

Vegetative mycelium: Colorless; 1.5 to 3.6 4; septa and clamps 
fewer than in fruiting mycelium, but fairly abundant; branching 
irregular, not abundant, not necessarily at right angles, with forking 
common; hyphez straight for the most part, contents homogeneous; 
anastomosing occasional; chlamydospores few, similar to those on 
submerged mycelium. 

Tertiary mycelium (aerial )— 

Fruiting mycelium: Colorless; 4 to 6.6 w; of unequal thickness, much 
of it with contents gone and only walls left; abundant protuberances, 
round or bluntly pointed; branching common, usually at clamps; septa 
and clamps abundant; anastomosing common; chlamydospores as above. 

Fomes roseus: - | 
Secondary mycelium— 

Submerged. ‘ 

Colorless; 0.8 to 3.6 yu, occasionally 4.6 u, with much small my- 
celium; septa and branching not abundant; clamps not observed; 
branching begins near tip of young growing hyphe; no secondary 
spores observed. 

Aerial. 

Colorless; smallest hyphze 0.8 to 1 uw, more commonly 2 to 3.1 uy, 
occasionally 3.8 to 4.7 4; septa not abundant; branching not abun- 
dant; may or may not be at septa; clamps few; anastomosing of 
smaller hyphe occasional; no secondary spores observed. 

Tertiary mycelium (aerial)— 

Colorless, pinkish in mass; 2 to 3 uw; no branches or clamps; stiff, 
hairlike. 

Lentinus lepideus: 
Secondary mycelium— 

Submerged. 

Colorless; 3.5 to 4 u; septa abundant, hyphe constricted at septa; 
branching may begin near tip of growing hyphe, not necessarily at 
septa or clamps; clamps fairly abundant; anastomosing occasional at 
clamps; chlamydospores colorless, thick-walled, usually ellipsoid, oc- 
curring intercalarily or terminally on short lateral branches; 8 to 
14 X 10 to 20 u. 

Aerial. 

Colorless; 2 to 3 uw; branching common, also septa; clamps few; 
chlamydospores colorless, 8 to 14 X 10 to 29 uw, usually ellipsoid, oc- 
casionally ovoid or ellipsoid-oblong, usually terminal, but occasionally 
intercalary, commonly empty, commonly showing secondary walls due 
to contraction of contents. 


24 BULLETIN 1053, U. S. DEPARTMENT OF AGRICULTURE, 


e 


Tertiary mycelium (aerial)— 

Colorless as a rule, with occasional hazel hyphe, may be slightly 
colored in mass; 2.2 to 5.6 uw; long, stiff, hairlike; chlamydospores as 
described in the secondary mycelium; thick walled; irregular hyphe 
common. 


DIFFERENTIATION OF THE CULTURES UPON AGAR. 


Agar plate cultures of the five fungi under consideration in these 
studies are readily distinguished macroscopically. Lenzttes sepiaria 
is readily distinguishable because of its scant superficial mycelium, 
even occasional lack of it, and the powdery appearance due to the 
oidia. Lenzttes trabea can readily be distinguished as to its second- 
ary mycelium by the presence of chlamydospores along with the 
oidia, inasmuch as the chlamydospores of L. sepiaria are very 
scarce and seldom found on malt agar. Its tertiary mycelium is 
dense, matted, and patchy and in color yellow-orange to ochraceous 
buff. It forms large fluffy masses at the upper ends of malt agar 
slants. 

Of the remaining fungi here studied, Yomes roseus may show 
only a white secondary mycelium, which will be either uniform or 
very irregular in thickness, or there will be formed a tertiary my- 
celium from pale-pink tints to old rose and Mars brown in color, Itis 
also a more slowly growing organism at its optimum temperature than 
Lenzites sepiaria, L. trabea, or Trametes serialis. Lentinus lepideus 
grows at about the same rate as Yomes roseus, taking 12 days at 
optimum temperature to cover a 10-centimeter Petri dish. Z'rametes 
serialis is a rapidly growing fungus, covering the dish in 7 days at 
optimum temperature. Lentinus lepideus soon takes on a brownish 


cast, forms umbonate abortive fruiting bodies in the Petri dishes, | 


and usually has a distinct aromatic odor. 

A conspectus of diagnostic characters of agar cultures of the 
five fungi is presented in key form. The characters are based on 
cultures at least 3 weeks old and grown at temperatures from 20° 
to 30° C. 


I. Oidia present. 

A. Growth usually white, scant and powdery, but occasionally more 
abundant, and shades of brown or sepia in color, especially fruit-body 
cultures; true chlamydospores scarce, but many spherical or pyriform 
Oidia may. be present. us ee ee Lenzites sepiaria. 

B. Early growth (secondary mycelium) scant and powdery, but usually con- 
taining many true chlamydospores; later growth (tertiary mycelium) 
abundant, containing no secondary spores, pale yellow-orange to light 
ochraceous buff in color; abortive poroid or irpiciform fruit bodies 
TOU WNCG ree ah et Lenzites trabea. 

II. No secondary spores present; tissue cultures soon becoming pink, old rose, 
or shades of brown; basidiospore cultures remaining white indefinitely 
or becoming pink ‘with Neo ee ee ee Fomes_ roseus. 


i 
4 


a 


FUNGI OF IMPORTANCE IN THE DECAY OF TIMBERS. 25 


III. Chlamydospores present, but no oidia. 

_- A, Mycelium tough, brownish in old agar cultures; with abortive fruit 
bodies, especially in plate cultures; covers 10-cm. Petri dish in 12 days 
at 28° C.; aerial chlamydospores often showing contraction of the 
protoplasm and formation of thick secondary walls; usually having a 
Semen aromma ric, OOGr en Jen Coe ek Ae ae Lentinus lepideus. 

B. Mycelium white; no abortive fruit bodies; covers 10-cm. Petri dish in 
seven days at 28° C.; chlamydospores more abundant in submerged 
0 EET MUA A IDEAS UPR 1 dl G0 Le AS ee RO Trametes serialis. 


EFFECT OF TEMPERATURE ON THE GROWTH OF THE MYCELIUM. 


The tests on the effect of temperature upon the growth of the my- 
celium were made on malt agar in 10-centimeter Petri dishes. The — 


a 6 2F- Te 
DECKEES CEN TIGRADE 


Fic. 2.—Effect of temperature upon the growth of the mycelium upon malt agar (shown 
in millimeters of radial growth from the inoculum). 


inoculum consisted of a block of agar 8 to 10 millimeters square, with 
its mycelium, cut from the young growth of a previously prepared 
Petri dish culture. This transfer was deposited upon the surface 
of the agar in the center of the dish. Growth was measured in 
millimeters radially from the edge of the inoculum. The results of the 
tests upon the five fungi are given in figure 2 and in Plate VII. For 
Lenzites sepiaria the optimum lies at 30° to 34° C. (85° to 93° F.). 
At 3° and 8° C. (37° and 46° F.), there was no noticeable growth 
in 8 days, and after a month there was no growth at 3° C. and 
only a millimeter or two at 8° C. At 40° C. (104° F.) results varied. 
Occasionally there was no noticeable growth until after 18 days, when 
it varied from 1 to 3 millimeters; at other times 1 to 5 millimeters was 
evident in 8 days. No growth took place at 44° C. (111° F.). Falck 
(14, pp. 127-129) obtained somewhat different results for this fungus. 


26 BULLETIN 1053, U. S. DEPARTMENT OF AGRICULTURE. 


He found the optimum to be 35° C. (95° F.), the minimum 5° C, 
(39° F.), and the maximum point 44° C. (111° F.). 

Lenzites trabea makes a moderately rapid growth, covering the 
dish in seven or eight days. It grows fastest at 28° C., although 
nearly as rapidly at 30° C. It grows only very slightly at 40° C. 
(104° F.). 7 

Trametes serialis grows at about the same rate as Lenzites sepiaria, 
covering the dish in 7 days. The optimum for 7’. serialis is at 28° C. 
(82° F.). No growth occurred at 34° C. (93° F.), and at 3° C. 
(37° F.) none was noticed until after 39 days, when it was seen to 
be alive and barely growing. /omes roseus is a more slowly growing 
organism, taking 11 days at the optimum temperature (30° C.) to 
cover the 10-cm. Petri dish used. At 3° C. there were signs of 
growth in 12 days, but very little at 36° C. (97° F.) and none at © 
40° C. (104° F.). Upon microscopic examination it was seen that 
at 40° C. hyphe had started to grow, but had died. Lentinus 
lepideus also grows at a moderate rate; in most of the tests the dish 
was not quite covered in 12 days. Its optimum was found to be 
28° C. (82° F.). Its range of growth was narrower than that of 
the other three fungi. No growth was noted at 8° C. (46° F.) in 
12 days, and at 36° C. (97° F.) there was less than 1 mm. in the 
same period. No growth was visible at 40° C. (104° F.). 


SECONDARY SPORES. 


INTRAMURAL DISSEMINATION OF FUNGI CAUSING DECAY. 


One of the most interesting problems in connection with the decay 
of building timbers is that of the intramural] dissemination of the 
causal organisms. Abundant proof is at hand to attest the activity — 
of the mycelium in spreading decay throughout a building by direct 
growth from one timber to another. Falck (16, pp. 245-247) has 
shown how the mycelium of the dry-rot. fungus (Merulius lacrymans) 
can grow through structures and even for some feet over brick and 
stone masonry from one piece of timber to another. Wehmer (67) 
has shown the same for cultures of Coniophora cerebella. 'The dis- 
semination of J. lacrymans by means of rhizomorphs is also well 
known (cf. Falck and others). The dissemination by means of 
basidiosporic fructification has already been mentioned. While con- 
ditions in textile and paper mills may occasionally favor the forma- 
tion of fruit bodies, of certain species at least, conditions also may 
prevail which will likewise prevent the formation of such fruit 
bodies. It has been shown that 7'rametes serialis can fruit and cast 
spores in the dark. On the other hand, Lenzites sepiaria can not 
form normal fruit bodies in the absence of light (see Falck, 15, for 
reference and discussion), and the same is true of Lentinus lepideus 


Bul, 1053, U. S. Dept. of Agriculture. PLATE VII. 


EFFECT OF TEMPERATURE UPON THE GROWTH OF THE MYCELIUM. 


Fig. 1.—Growth of Lenzites sepiaria for 8;days: 1A, at 18° C.; 4A, at 32° C.; 30A, at 36° C. Fia. 


2.—Growth of Lenzites trabea for 7 days: 81A, at 16° C.; &2A, at 28° C.; ,at 36°C. Fie. 3.— 
Growth of Trametes serialis for 8 days: 12A, 12° C.; 15A, at 28° C.; 16A, at 32° C. Fie. 4.— 
Growth of Fomes roseus for 11 days: 6A, at 12°C.; 10A,at30°C.; 11A,at34°C. Fie.5.—Growth 
of Lentinus lepidews for 12 days: 19A, at 24° C.; 21A, at 28° C.; 23A, at 32° C. 


Bul, 1053, U. S. Dept. of Agriculture, PLATE VIII. 


FUNGI STUDIES OF IMPORTANCE IN THE DECAY OF BUILDING TIMBERS. 


(X 523.) 
Fic. 1.—Oidia of Lenzites sepiaria from malt-agar culture. Fic. 2.—Stages in formation of 


chlamydospores of Trametes serialis on secondary mycelium in malt agar, with a few thin- 
walled chlamydospores. Fic. 3.—Oidia and mycelium of Lenzites sepiaria upon fibia of 


cockroach allowed to roam over wood block culture over night. 


a. ae ae eee 


FUNGI OF IMPORTANCE IN THE DECAY OF TIMBERS. 27 


(Buller, 6, p. 428; 7, p. 6; and Jaczewski, 26, p. 407). Under these 
circumstances the question naturally arises whether or not secondary 


_ spores might be produced by some of these organisms and thus ac- 


count for the rapidity with which decay spreads in certain types of 
buildings. In certain places in mills, as basements and between 


4 _ floors, for example, light may be insufficient for fruit-body forma- 


tion, yet this lack of light and the abundance of moisture would be 


highly favorable for the growth of superficial mycelium, and hence, 


perhaps, for the production of secondary spores. With these possi- 
bilities in mind, considerable attention was paid to the observation 
and study of the secondary spores formed by the five organisms in 
question. 


REVIEW OF THE LITERATURE OF SECONDARY SPORE FORMATION. 


GENERAL SUMMARY. 


The subject matter relative to secondary spores has been well sum- 
marized by Lyman (37). His conclusions (p. 202) were: That a ma- 
jority of the hymenomycetes have no secondary spores; that oidia 
are common among the Polyporacee and Agaricacee and are con- 
fined to these two families; that chlamydospores occasionally occur 


in connection with the basidial fructification and are quite widely 


distributed on the mycelium of all families; and that conidia and 
other highly specialized methods of reproductions (bulbils, etc.) are 
rare and occur more frequently in the Thelephoracee than in the 


higher families. Since Lyman’s paper, only scattering references to 


secondary spores have appeared. Of these only a few are of interest 
here. Marryat (32) found chlamydospores of Pleurotus subpalmatus 
in the vessels of wood-block cultures. Rumbold (49) not only re- 
ported secondary spores for the first time in a few species of wood- 
destroying fungi, but studied their formation, germination, and sub- 
sequent development. Falck produced two comprehensive volumes, 
one in 1909 on the decay produced by species of Lenzites (15) and the 
other in 1912 on the decays caused by species of Merulius (76). In 
these he takes up in a thorough way the occurrence, the methods and 


_ conditions of formation, and the germination under various conditions 


of the oidia in the species considered. In the later work (6, p. 182- 
133) he makes some general remarks upon these oidia. He considers 
them of two kinds—a transition, or tiding over, form (Ubergangs- 
fruchtform), as found in Merulius, and a true secondary form 
(Nebenfruchtform), as found in Coniophora. The former he says 
are not formed under normal conditions (natiurlichen V erhaltnissen) 
but only when conditions become unfavorable for growth of the 


‘fungus. Their viability is reduced and they are capable of being 


disseminated only to a slight degree. The latter are found under 


28 BULLETIN 1053, U. S. DEPARTMENT OF AGRICULTURE, 


normal conditions of growth, and their formation is independent of 
environmental conditions. They germinate immediately and nor- 
mally, are formed in loose dustlike masses, and are easily removed. 


The former he considers a facultative transition form and the lat- 


ter a true propagative form. 

Hotson in two papers (22 and 23) extended and summarized our 
knowledge of bulbils and similar propagative forms, and added the 
finding of bulbils in a few basidiomycetes. Learn (28), in his cul- 
tures of Pleurotus ostreatus, noted the formation of new mycelial 
growths at the base of wood-block cultures below blocks bearing 
oidia. This suggested the shedding of these oidia from above. Weir 
(62) noted a Ptychogaster form in connection with Trametes 
suaveolens growing naturally, and he remarks that in the damp 
woods of Idaho there are many abnormal polyporoid forms, some 
of them conidial. In FYomes officinalis, Faull (18) found chlamydo- 
spores not only in cultures but also in the crust of the sporophores. 
The writer has found the chlamydospores of this fungus on rotting 
wood in nature (55). Hailey (20) reviewed the status of the conidia 
of Fomes annosus. 


REFERENCES TO THE OCCURRENCE OF SECONDARY SPORES IN NATURE. 


The references to secondary spores occurring in nature are quite 
numerous. Perhaps the least understood of the fungi producing 
secondary spores are the Ptychogasters, which are considered ab- 
normal conidial or chlamydospore fructifications of the polyspores. 
Observations on the Ptychogasters occur chiefly in the older litera- 
ture, and reference may be had to Boudier (3 and 4), De Seynes (50, 
51, 62, 58, 54), Richon (48), Ludwig (30), Patouillard (42 and 43), 
Brefeld (5), and Weir (62). Then there are the spores reported as 
conidia, called “ wet-weather spores” by Lyman (31, p. 1385), who 
said that until these spores had been more thoroughly investigated 
their nature must be regarded “as uncertain and their occasional 
production as of doubtful importance to the fungus.” (Cf. Patouil- 
lard, 47, 44, 46; Eichelbaum, 77; and Massee, 33.) Of the references 
to secondary spores in nature the status of which is more certain, 
we might mention the following: Chlamydospores on the hairs of the 
stipe of Pleurotus ostreatus (Patouillard, 39) and in the hymenium 
(Matruchot, 34); chlamydospores in groups or singly in Z'rametes 
rubescens (Daedalea confragosa) (Patouillard, 40) ; chlamydospores 
in fruit bodies of Polyporus sulfureus (De Seynes, 50, 51) ; conidia 
(chlamydospores according to Lyman, 31, p. 136) in the hymenium 
of Hydnum coralloides (De Seynes, 53); terminal chlamydospores 
in Fistulina hepatica (De Seynes, 50) ; chlamydospores on and in the 
pileus of Vyctalis asterophora and \. parasitica and conidia of Fomes 


| 
| 
j 
j 


a ee ee 


lens 


’ 5 fi 
~~ ee 


G2 EE A es 


FUNGI OF IMPORTANCE IN THE DECAY OF TIMBERS. 29 


annosus found by Olsen (Brefeld 5, p. 177) ; chlamydospores between 
the margin and the poriferous zone in Polyporus bambusinus 
(Patouillard, 45); conidia (chlamydospores according to Lyman) 
in Stereum disciforme and all over the hymenium of Aleurodiscus 
oakesti and A. amorphus (Patouillard, 46); conidia on racemose 
organs in the hymenium before formation of basidiospores in species 
of Aleurodiscus (Burt, 9, p. 198) ; viable chlamydospores on branches 
of the stipe of Collybia racemosa (Stefan, 59); helicoid conidia on 
hairs arising from the young veil and from the margin of the 
developing pileus of Lentodiwm squamulosum (Lentinus tigrinus 
Fr.) (Lyman, 37; p. 186) and on the mycelium overgrowing the gills 
of the same fungus (Murrill, 38, p. 296). Further, Cool (10) found 
oidia coming from the pileus during basidiospore casting of Collybia 
velutipes (p. 9) and chlamydospores along with the basidiospores of 
Sphaerobolus stellatus (p. 21). She also reports that she found a 
great many more oidia than basidiospores in the hymenial layer of 
Collybia velutipes and wart-shaped heaps ‘of oidia on the dried fruit 
bodies of this fungus. Long and Harsch (29) report the chlamydo- 
spores of Lentinus lepideus. We have already mentioned Weir (62) 
and the observation of Faull (78) and the writer (55) on the chlamy- 
dospores of Pomes officinalis. 


REFERENCES TO THE IMPORTANCE OF SECONDARY SPORES IN THE DISSEMINATION OF 
FUNGI. 


There are a few references to the importance of secondary spores 
in the dissemination of fungi. Eidam (12, p. 245) concluded that . 
there was no natural secondary reproduction in Cyathus striatus 
and that the oidia were an abnormal appearance, although they 
might tide over unfavorable conditions. In speaking of the failure 


_ of Hartig’s isolation trench in checking the spread of /'omes annosus, 


Brefeld (5, pp. 153 and 179-185) suggested as the reason that 
conidia were formed by this fungus that they infected the cut roots 
and thus produced more disease than normally occurred. Brefeld 
never found conidia growing naturally, although he reports such a 
finding by Olsen (4, p. 177), but he obtained them in the laboratory 
on-mycelium collected in the woods (4, p. 153). Hiley, in reviewing 
the status of the conidia of this fungus in relation to decay of the 
larch, reports (20) the production of conidia in wood cultures and 
upon sterilized soil. He believes it probable that the mycelium of 
Fomes annosus “may grow on forest soil and bear conidia” (p. 115) 
and that one of the means of infection of the host is by these conidia 
(pp. 115, 121, 123). Tubeuf (60, p. 103) had nothing concrete to 
offer on the propagation of Merulius by secondary spore forms, but 
emphasized the theoretical importance of such. He pointed out that 


30 BULLETIN 1053, U. S. DEPARTMENT OF AGRICULTURE. 


the basidiospores of the dry-rot fungus are difficult to germinate and 
may have low germinability in nature. He further states that the 


chlamydospores (asserted to be oidia by Falck) if found outside arti- 


ficial cultures would probably contribute to the spread of the fungus. 
Falck (16, p. 1382), on the other hand, maintained that the oidia 
of Merulius were not true propagation organs. The same writer in 


1902 (13, p. 319) remarked that insects must spread the oidia of | 


Hypholoma and Pholiota, which are formed in abundance on firm 
substrates. He believed that the formation of oidia on blocks infected 
with Collybia velutipes placed in moist moss illustrated the im- 
portance of these spores in nature. ‘These oidia were formed in col- 
onies in the air, undoubtedly for insect dissemination, he avers, but 


he doubts whether they could be detached by the wind. Falck (25, 


p. 144) also maintained that the tertiary oidia of Lenzites sepiaria 
“doubtless play an important part as organs of propagation, inas- 
much as the spores might easily be carried away by animals in 
creases of their bodies, etc. A somewhat rough shaking loosens single 
end-spores from one another, and these can easily be collected on 
slides held beneath.” 

Miinch (37, p. 577), however, believes that oidia do not possess in 
nature the great significance for the spread of the fungus -which 
Falck claimed for them. He observes that the conditions of oidia 
formation are not clear, that their formation in nature is not possible 
in cases that have come to his attention, because of the inability of the 
fungus to get to the air, and that direct observations of oidia in 
nature are lacking. He asserts that this form of reproduction is 
merely a makeshift at best and not a normal reproductive form. 
Faull (18, p. 201), as mentioned above, found chlamydospores in 
the crust of sporophores of /omes officinalis and expressed the belief 
that they are a means of reproducing the fungus, although the 
viability of these chlamydospores appearing naturally was not tested. 
The finding of chlamydospores of this fungus in nature by the 
writer (55) has suggested their importance in the spread of the 
fungus. 


OCCURRENCE OF SECONDARY SPORES IN CULTURES OF THE 
FUNGI STUDIED. 


Of the five fungi used by the writer in these studies, secondary 
spores have been found in four. Oidia have been previously re- 
ported in cultures of Lenzites sepiaria by Rumbold (49) and Falck 
(15) and chlamydospores also by Falck. Long and Harsch (29) 
reported the occurrence of chlamydospores in cultures of Lentinus 
lepideus. As far as the writer knows, the chlamydospores formed 
by Trametes serialis have not been reported, although Mez (395, 
p. 116) mentioned a brown corky Ptychogaster form of this species 


| 


| 
| 
. 


: 
: 
| 
| 


ate? 1h et ok ys 


FUNGI OF IMPORTANCE IN THE DECAY OF TIMBERS. ob 


with deep pores. Brefeld (45, p. 106) reported in 7'’rametes serialis 
aerial oidia which would germinate and made the observation that 
their formation occurred only on young mycelium, never on old. 
The writer’s cultures have developed no oidia. The oidia and 
chlamydospores in Lenzites trabea have not been reported. No 
secondary form has been noted in Homes roseus. Chlamydospores 
have been seen in cultures of Lenzites sepiaria, but have been scarce. 
They could not have appeared abundantly in Falck’s cultures, for 
he little more than mentions them. All his references to secondary 
spore production by this fungus are to the oidia, and he describes no 
physiological tests upon the chlamydospores. 

Oidia have appeared to a limited extent in the submerged my- 
celium of Lenzites sepiaria, chiefly in the hanging agar drop cultures 
(Pl. III, figs. 3 and 10), while the aerial oidia have been quite abun- 
dant with some variations (PI. III, figs. 4-7; and Pl. VIII, fig. 1). 
Oidia have been quite abundant also in wood cultures. What little 
aerial mycelium forms on either wood or agar breaks up almost en- 
tirely to oidia. ‘The occurrence and method of formation has been 
described sufficiently by Falck (15, pp. 139-140). He describes pri- 
mary, secondary, and tertiary oidia according as they are formed on 
primary, secondary, or tertiary mycelium. The secondary oidia 
are never formed on the natural substrate of the fungus, according 
to him, but abundantly on agar, while the whole superficial growth 
of tertiary mycelium on agar or wood forms oidia in moist air. 
Chlamydospores and chlamydosporelike bodies (PI. II, figs. 12 and 
13) are found in small numbers upon the submerged mycelium. The 
secondary mycelium of Lenzites trabea develops oidia in abundance 
(Pl. IV, fig. 2) and chlamydospores in fair numbers (PI. IV, figs. 3 
and 4). The oidia are formed on the superficial mycelium and the 
chlamydospores on the submerged so far as can be determined. 
Some of the latter spores are thin walled and appear much like 
rounded oidia. Many of the chlamydospores show the contraction 
of the protoplasm and the abandoned cross walls (Pl. IV, fig. 4), 
as in the chlamysdospores of 7’rametes‘serialis and Lentinus lepideus. 

The chlamydospores of 7’rametes serialis (P1. IV, figs. 6, 7, 8; and 
Pl. VIII, fig. 2) have appeared regularly in the writer’s cultures 


and fairly abundantly. They are found for the most part on the 


submerged mycelium, although sparingly in the aerial fruiting my- 
celium at the upper end of older agar slant cultures, where abortive 
fruit bodies are formed. The method of development is that de- 
scribed by Lyman for other basidiomycetes (3/7, p. 150, pls. 19, 21, 
and 22) and illustrated in Plate IV, figure 6, and Plate VIII, figure 2. 

The chlamydospores of Lentinus lepideus (Pl. V, figs. 4 and 5) 
have never been found abundantly. They occur in a living condition 


32 BULLETIN 1053, U. S. DEPARTMENT OF AGRICULTURE. 


on the submerged mycelium after about 10 days, but are empty and 
dead in 2 months. 

The secondary spores of the four species considered here are 
formed on all the nutrient media tried, although in varying quanti- 
ties, but Lenzites sepiaria is the only species so far known to form 
them on wood. Temperature has no appreciable effect on the forma- 
tion of these spores on malt agar. Early in the work it seemed as 
if light favored the formation of oidia by Lenzztes sepiaria and that 
darkness prevented it, but a variety of tests, variously checked, 
failed to give absolutely consistent results. Yet it was found that 
cultures started in the light nearly always BOR mEG oidia, while those 
in the dark seldom did. 


GERMINATION STUDIES OF THE SECONDARY SPORES. 


The oidia of Lenzites sepiaria germinate readily and to practically 
100 per cent on agar. The cylindrical oidia as a rule simply lengthen 
out at either end or both ends with no swelling, so that no sign of 
the original oidium is left (Pl. III, fig. 11). Germination may be- 
gin, however, with a swelling of the oidium, at one end or in the 
middle, and the germ tube may then arise from either the swollen or 
unswollen ends (Pl. III, fig. 9). The club-shaped oidia which are 
found occasionally may send out one or more tubes from either the 
swollen or unswollen ends. In water the tubes are attenuated. The 
chlamydospores of Lénzites sepiaria germinate normally (PI. III, 
fig. 10). The oidia and chlamydospores of Lenzites trabea germi- 
nate in a manner similar to those of L. sepiaria. The chlamydo- 
spores of Z7’rametes serialis (Pl. IV, fig. 9), and Lentinus lepideus 
send out tubes from either end of the ellipsoid spores, although 
usually from only one end. 

Germination tests were carried out upon the oidia of Lenzites 
sepiaria and Lenzites trabea and the chlamydospores of 7rametes 
serialis, The chlamydospores of L. sepiaria and L. trabea were not 
readily obtainable in sufficient quantities and were hard to separate 
from the oidia. The chlamydospores of Lentinus lepideus could not. 
be obtained in a condition which would allow of their manipulation. 
The chlamydospores of all four fungi occur chiefly, if not entirely, 
on the submerged mycelium in the agar. Those of 7vametes sérialis 
could be obtained in sufficient numbers by scraping the submerged 
mycelium, with as little agar as possible, from the surface of the 
culture, then macerating this material between two thick glass slides 
which had been previously flamed and finally removing this macer- 
ated mixture to sterile water blanks. ‘The chlamydospores were 
separated from the mycelium by this process and the mycelium 
sufficiently injured so that it did not interfere with germination 


FUNGI OF IMPORTANCE IN THE DECAY OF TIMBERS. 33 


tests. This method was not entirely satisfactory, but was the best 
that could be used in view of the lack of chlamydospores in quantity 
on the aerial mycelium. This method would not produce results 
with the chlamydospores of Lentinus lepideus, however, because they 
could not be separated from the mycelium, which appeared to be 
rather tough. The spores were not abundant in the first place, and 
germination tests on the few obtained were unsatisfactory, because 
the mycelium in the macerated mass overgrew the germinating 
chlamydospores. 

All of the secondary spores germinate readily on various agars or 
in tap water. In distilled water numerous tests have shown that 
the oidia germinate sparingly (usually less than 1 per cent and 
produce only asmall amount of attenuated mycelium. The chlamydo- 
spores could not fairly be tested in distilled water, on account of 
the difficulty in obtaining the spores free from mycelium, agar, etc., 


- as explained above. On red spruce the secondary spores germinate 


normally as to time and manner, although forming attenuated 
mycelium. 
TEMPERATURE. 


The curves shown in figure 3 represent the effect of temperature 
upon the germination of oidia of Lenzites sepiaria and L. trabea 
and the chlamydospores of Z’rametes serialis, It will be noted that 
most of the oidia of both species germinated even at the extreme 
temperatures. At 5° C. (22° F.) in 5 days only 35 per cent of the 
oidia of L. sepiaria had germinated, 75 per cent in 11 days, and 80 
per cent in 14 days. At44° C, (111° F.) the oidia of both Z. sepiaria 
and L. trabea germinated to practically 100 per cent in 20 hours. 
The oidia of L. sepiaria germinated most rapidly at 36° C. (97° F.) 
and that of L. trabea at 82° C, (89° F.). 

About 75 per cent of the chlamydospores of Trametes serialis ger- 
minated between 20° and 32° C. (68° and 89° F.). In three weeks 
35 per cent germinated at 50° C., but none germinated at 36° in re- 
peated tests. The rate of development was optimum around 28° 
and 32° C. (82° and 89° F,). 

A comparison of the cardinal temperatures for rate of germina- 
tion of the basidiospores and secondary spores with growth of the 
mycelium of the five fungi studied shows that they correspond quite 
closely. The optimum for basidiospores extends over a little wider 
range of temperature than for the secondary spores or mycelium. 
The maximum temperature for the germination of the basidiospores 
is somewhat higher, by a few degrees, than for the growth of the 
mycelium of all five fungi. The oidia of Lenzites sepiaria and L. 


34 BULLETIN 1053, U. S. DEPARTMENT OF AGRICULTURE. 


trabea showed little or no retarding effect in percentage of germina- 
tion at 44° C, 

A single test upon the effect of cold on the oidia of Lenzites 
sepiaria and chlamydospores of Z’rametes serialis was made. Slides 


FER CENT 


PER CENT 


MICRONS FEF? BOHOUW RS 


GR F-O F8 


16 aS 
LEGHLLES CENTIGRADE 


Fig. 3.—Effect of temperature upon the germination of the oidia of Lenzites sepiaria and . 
L. trabea and of the chlamydospores of Trametes serialis. A, Effect of temperature 
upon the percentage of germination, showing the maximum percentage obtained, regard- 
less of the time element; B, percentage of germination in 20 hours; C, rate of growth 
of the thalli in 20 hours (shown in microns). 


were left out of doors over night when the temperature varied from 
—19° C. to —23° C. (—3° to —10° F.). The next morning germina- 
tion tests were made, and it was found that the oidia had not been 


FUNGI OF IMPORTANCE IN THE DECAY OF TIMBERS. 35 


affected, practically 100 per cent germination resulting, while the 
iting dospores did not germinate at all. 


LIGHT. 


The diffused light from an east window during the winter appar- 
ently had little effect on the germination of the secondary spores. 
The oidia of Lenzites sepiaria and L. trabea germinated almost per- 
fectly in diffused light or in the dark, although the development was 
somewhat more rapid in the dark. The same is true of chlamydo- 
spores of 7rametes serialis, except that the percentage was between 
50 and 60 rather than around 100. 

in the month of May, 10 hours of direct sunlight acting upon the 
secondary spores upon agar not only inhibited germination during 
_ that period but prevented subsequent germination altogether. Ex- 
_ periments upon the killing effect of direct sunlight upon these spores 
when resting could not be carried out, inasmuch as it was impos- 
_ sible to separate the effects of drying from the effects of sunlight, 
_ because, as will be shown, drying etna reduces the percentage 
_ of germination. 


DRYING. 


There have been a few reports of the resistance of secondary spores 
to drying. De Seynes (50) found that the conidia of Fistulina 
hepatica germinated after four years. Brefeld (45, p. 153) said that 
the conidia of Yomes annosus retained their viability for one year 
and a few germinated after two years of drying. He also stated 
(5, p. 27) that the oidia of PAlebia merismoides resisted drying for 
a month and some germinated after six months. According to Falck 
(15, p. 146) the aerial oidia of Lenzites sepiaria are resistant to dry- 
ing. Ojdia subjected to drying in the presence of calcium chlorid 
_ germinated after one year, and they were not killed after an exposure 
of several hours to 60° C. (p. 147). On the other hand, Lyman 
(31, p. 149) concluded that in general the retention of viability by 
oidia is of short duration. 

_ The writer’s results with the oidia of Lenzites sepiaria and L. tra- 

bea agree with Lyman’s conclusions. Agar cultures with an abun- 
_ dance of oidia and oidia on glass slides were dried for varying 
periods. After one day of drying the percentage of germination 
was much reduced, and usually to less than 1 per cent. In some 
cases, however, a very small percentage of oidia would germinate 
after a few months at room temperature, perhaps because of pro- 
tection of certain oidia by large masses of others. It was thought 
that if any resistance to drying should be manifested it would be 
on the natural substrate for the fungus, but the results were the 
same as on agar. 


36 BULLETIN 1053, U. S. DEPARTMENT OF AGRICULTURE, 


The chlamydospores of Trametes serialis proved no more resist- — 


ant. It is possible, however, that the conditions under which they 


were formed (in a moist medium) and their previous wetting in ; 


obtaining them may render them more sensitive to drying. 
ALTERNATE WETTING AND DRYING. 


The oidia of Lenzites sepiaria and L. trabea do not survive alter- 


nate wetting and drying. Oidia were removed in quantities from ' 


an agar plate culture to glass slides. Two slides were retained as 
checks and the oidia on two others were wet with sterile distilled water 
and immediately put away until dry. One slide was allowed to dry 
under room conditions, while the other was dried in the presence of 
calcium chlorid. Germination tests were then made. After 16 hours 
the controls showed practically perfect germination, while of the wet 
and dried oidia three Van Tieghem cells showed less than 1 per cent 
and one 5 per cent germination. Repetitions of the test gave similar 
results. 


EXPERIMENTS UPON THE DISSEMINATION OF THE OIDIA OF 
LENZITES SEPIARIA. 


Flask cultures of Lenzites sepiaria and L. trabea obtain a much 
better start than cultures of the other fungi, because of the oidia. 
The water in the tube containing the bean-pod cultures used as 
inoculum becomes a suspension of oidia, and these are distributed 
all over the flask to start centers of growth, whereas cultures of 
fungi possessing no oidia can only be spread from the inoculum 
and consume about one month in covering all the blocks in the 
flask. In the light of these facts a few experiments were carried 
out with a view to ascertaining by what means and how easily 
the oidia of this fungus might aid in dissemination. It is realized 
that any points made here are contingent for their importance 
upon the question as to whether or not the oidia occur naturally. 


Inasmuch as Falck (73, p. 319) doubted whether wind would be — 


of any importance in disseminating oidia, the writer set out to de- 
termine how easily the oidia might be removed from plate cul- 
tures. A new transfer was inverted over a sterile agar plate, sealed 
with gummed paper, and set away in the incubator. In the first 
test with L. sepiaria, an abundance of oidia were found upon the 
sterile agar plate after a week. Repetitions gave inconsistent re- 


sults, but it was shown that small numbers of oidia may be released — 


during their formation. Shaking a plate culture over a sterile agar 
plate yielded results similar to those reported by Falck (14, p. 144). 


Oidia were dislodged in some cases, but not in all. The same test — 
was tried with Collybia velutipes, anid pure cultures were obtained, 


from oidia shaken off. 


at een a ve 


i i i ee 


a, ee te Die op en | Oe « ee ee _ nn 


FUNGI OF IMPORTANCE IN THE DECAY OF TIMBERS. 37 


Attempts were next made to dislodge oidia from agar-plate cul- 
tures by air currents from an electric blower delivering 1.4 cubic feet 
per minute. The apparatus was so set up that at least a part of the 
oidia removed would lodge on sterile agar plates. From cultures 
with a very heavy development of oidia, a very few were dislodged, 
as determined by microscopic examination of the surface of the 
sterile agar plates and subsequent growth. An electric fan making 
a much stronger current of air removed larger, though not consider- 
able, numbers of oidia. Oidia on wood blocks from cultures were not 
removed any more readily, inasmuch as they are formed only in 
moist atmospheres and are themselves moist and sticky. The same 
procedure was tried with other species showing secondary spores in 
culture. Individual oidia or small clusters were likewise dislodged 
from agar cultures of Collybia velutipes. The stronger current of 
air removed a few of the chlamydospores of Yomes officinalis, but 
oidia could not be removed from cultures of Coniophora cerebella 
or Merulius lacrymans or chlamydospores from cultures of 7’rametes 
robiniophila or Fomes igniarius. It is thus seen that secondary 
spores of most of the species mentioned do not appear to be adapted 
to dissemination by wind. 

Oidia are readily removed by contact. Prints can be made upon 
glass slides or cover slips by simply allowing the glass to touch the 
surface of a culture. More sticky substances like agar retain more 
oidia than glass. The obvious application of these facts is insect 
dissemination, for insects with sticky feet and hairy or bristly ap- 
pendages should be able to remove and carry away large numbers of 
the moist oidia. A cockroach caught in the laboratory was placed 
upon agar cultures of Lenzites sepiaria for a few minutes. Exami- 
nation of the roach’s appendages under the microscope disclosed 
large clumps of the oidia stuck to the tarsi. Another roach placed 
upon an agar culture was transferred to a sterile agar plate, allowed 
to remain a few seconds, and then the plate was incubated. In three 
days the plate showed a winding growth of Lenzites sepiaria and 
contaminations, chiefly Penicillium, presumably where the roach had 
walked over the agar‘during his captivity. A cockroach was then 
placed in a flask containing a wood-block culture of Lenzites sepiaria 
and examined after a few minutes. A few oidia were found upon 


the pads of the tarsi and on the bristles of the legs and antenne (PI. 


VIII) fig. 3). 

Water will dislodge large quantities of oidia from agar or wood 
cultures. Sterile water dropped from a pipette upon the inoculum 
of a new transfer will carry or splash large numbers of oidia on the 


- surrounding sterile agar. 


From the above results it is concluded that atta occurring either 
on wood or agar are moist, sticky spores, not adapted to air dissemi- 


38 BULLETIN 1053, U. S. DEPARTMENT OF AGRICULTURE. 


nation, but excellently adapted to dissemination by insects or drip- 

ping water. The practical application of these facts is obvious. If 
secondary spores occur outside of artificial cultures, there is no place 
_ more suitable for their formation than in the structures of wet oc- — 
cupancy referred to. In these structures, where conditions are moist, — 
there would be insects or animals, such as sow bugs and cockroaches, — 
and there is commonly dripping water, precipitation water upon cool — 
masonry, around cold-water pipes, etc. ) 


OCCURRENCE IN BUILDINGS OF THE SECONDARY SPORES OF — 
THE FUNGI STUDIED. 


The step following the demonstration that oidia can disseminate 
fungi, such as Lenzites sepiaria and L. trabea, is to prove that such © 
oidia occur naturally in buildings. The outstanding fact is that 
many European writers have suggested the importance of the sec- — 
ondary spores in the economy of the fungus, if found naturally, and 
that no one has yet reported such occurrences. The writer has little 
information on the subject. The only secondary spores found in mills 
are the chlamydospores on the mycelium overgrowing the gills of 
fruit bodies of Lentinus lepideus (Pl. V, fig. 6). These are formed © 
quite abundantly, but thus far nothing is known of their ability to 
disseminate the fungus. The spores which the writer found were 
on old fruit bodies, and tests as to their ability to germinate failed. — 
There is, of course, the possibility that freshly formed chlamydo- — 
spores may germinate, and, if so, they would disseminate the fungus 
much as do the basidiospores which are overgrown and imprisoned 
by the chlamydosporic mycelium. This means of dissemination 
would appear to be not so efficient a method as by the basidiospores 
which they replace, because the basidiospores should be hghter and 
hence capable of wider dissemination. 

It is known that certain fungi do form superficial cone within 
the structures referred to in hese studies as well as out of doors. 
Falck (15, p. 154) relates that the fruit- body-forming mycelium | 
(fruktifikative Oberflachenmycel) of Lenzites sepiaria is found on 
moist places on beams, and he states (5, p.-143) that it is capable 
of producing oidia, although he has not reported the finding of these 
oidia in buildings. The writer has examined some superficial myce- 
lium of Lenzites sepiaria and L. trabea upon planks secured from 
mill roofs, but the presence of oidia or chlamydospores as yet has not 
been definitely established. 


SUMMARY. 


In textile and paper mills prevailing conditions of humidity and 
temperature provide a favorable environment for the development 
of wood-decaying fungi. Under such conditions poorer grades of 


FUNGI OF IMPORTANCE IN THE DECAY OF TIMBERS. 39 


timber, such as inferior southern pine, spruce, and hemlock, which 
have been used in mill construction in recent years, are readily at- 
tacked and destroyed. ' Hence, the losses through decay by a certain 
group of fungi are large. Because of the practical importance under 
mill conditions of Lenzttes sepiaria, L. trabea, Trametes serialis, 
Fomes roseus, and Lentinus lepideus, studies upon the physiological 
relations of the basidiospores, mycelium, and secondary spores were 
undertaken, particular attention being paid to those factors influenc- 
ing intramural dissemination. 

All five of these fungi have been found fruiting more or less com- 
monly upon mill roofs or in basements. Lenzites sepiaria and L. 
trabea do more damage to coniferous roof timbers than has here- 
—tofore been reported. 

The basidiospores of the five fungi will germinate upon various 
agars, or wood, in tap water, and irregularly in distilled water. 

At 40° C. the basidiospores of Lenzites sepiaria will germinate in 
large percentages, while those of L. trabea and Fomes roseus give 
small percentages. ‘The spores of the other two fungi will not germi- 
nate at this temperature. The optimum temperatures for rapidity 
of germination are: Lenzites sepiaria, 32° to 385° C. (89° to 97° F.) ; 
L. trabea, 28° to 32 ° C. (82° to 89° F.) ; Trametes serialis, 30° to 32° 
C. (86° to 89° F.); Fomes roseus, 28° to 32° C.; Lentinus lepideus, 
28° C. Large percentages of the spores will germinate at the lower 
temperatures within the range of growth for each fungus if sufficient 
time is allowed. The percentage of germination is the criterion 
which best shows the effect of temperature upon me viability of the 
spores. 

Diffused light did not affect the germination of the spores. The 
basidiospores of these fungi would not germinate in direct sunlight 
in May, and after two days of exposure few or no spores would germi- 
nate when put in the dark. Two days of direct sunlight in May 
acting upon dry spores usually killed all but a very small percentage, 
if not all of them. The germ tubes showed no phototropic responses. 

In drying tests, basidiospores of 7'rametes serialis and Lentinus 
lepideus (aged 10 days and 7 months, respectively) were killed in 
about 10 weeks’ exposure at 28° and 32° C. (82° and 89° F.) and in 
about a month at 36° C. (97° F.). With fresh spores at 40° C. 
(104° F.), Lenzites sepiaria survived two months and Trametes 
sertalis six weeks in an unfinished test. Spores of Fomes roseus five 
months old were killed in one week at the same temperature. 

Alternate wetting and drying is destructive to the spores of these 
fungi. This applies either to the wetting with free water or oa 
to atmospheric moisture and subsequent drying. 

Basidiospores of Lenzites sepiaria gave a germination of 25 per 

cent after 2 years and 10 months of storage in an ice box; those of 


40 BULLETIN 1053, U. S. DEPARTMENT OF AGRICULTURE. 


L. trabea 50 per cent after 1 year; spores of 7’rametes serialis 2 per — 
cent after 4 years and 8 months; those of /omes roseus less than 1 
per cent after 18 months; and those of Lentinus lepideus less than 1 
per cent after 2 years oid 7 months. 

All but Fomes roseus have the ability to cast large aneabead of 
spores and dre shown to be capable of doing so within buildings. 
Lenzites sepiaria cast spores six times in experiments upon the ability 
of the sporophores to survive successive wetting, casting, and drying. 
A fruit body of 7rametes serialis in the dark in the fungus pit cast 
spores for 15 days successively. 

Observations upon fruit bodies of 7’rametes serialis in the bottom 
of a closed fungus pit showed that slight convection currents of air 
carried spores upward and throughout the pit. In mills, air cur- 
rents caused by machinery, humidifiers, and heating pipes are of im- 
portance in disseminating spores cast into the air. Sow bugs were 
observed in this pit beneath the sporophores and were found to bear 
large numbers of the spores upon their bodies and appendages. The 
possible importance of insects and other animals in the dissemination 
of these wood-destroying fungi is suggested. 

A description of the macroscopic and microscopic characters of 
malt-agar cultures of the fungi, with a key for identification, is given. 

The cardinal temperatures for mycelial growth were found to be 
as shown in Table 5. 


TABLE 5.—Cardinal temperatures for the growth of the mycelium of certain 
wood-destroying fungi. 


Cardinal temperatures (° C.). 


Species. 
Minimum. | Optimum. Maximum. . 
MONA LeSISCplanlas ... 0050 a seaae ese ee mee eee ee ome About 8...| 30 to 34.. hee ve 40. 
Lenzites trabea.......... Ctysapes sooth ude aie. ove! A Sho Be 28 to 30....; Little above 36. 
Trametes serialis. ............ Dee Sisind oe eee oe eee ADOUt 322.| Zor lee eee Between 32 and 37. 
Homes. rosewsved «ib asdous. sews eee. he eee EE iad Below: 4. .5| 0scccesnce Above 
HEHLINUS TOPIMCUS's .0.c5s cote cones cad: ce eee ee te About'3.2'| (28225. hence Betweon 36 and 40. 


Secondary spores of certain hymenomycetes have been reported 
by several writers as occurring naturally, and their importance in — 
the economy of the fungi has been suggested. Studies were made 
upon the secondary spores of four of the fungi under consideration ~ 
in view of their possible occurrence in a mill environment. Oidia and — 
few chlamydospores were found in agar cultures of Lenzites sepiaria, 
and oidia also in wood cultures, and both kinds of spores in agar — 
cultures of LZ. trabea. Chlamydospores were found in agar cultures 
of Trametes serialis and Lentinus leydeus. | : 

Certain of the physiological relations of the oidia of Lenzétes 
sepiaria and L. trabea and the chlamydospores of Trametes serialis — 


FUNGI OF IMPORTANCE IN THE DECAY OF TIMBERS. 41 


were studied. The germination temperatures corresponded closely 
with those of the basidiospores of the respective species except that 
the oidia germinated better at the higher temperature tried. Dif- 
fused light had no effect upon germination. Ten hours of direct 
sunlight in May prevented the germination of the secondary spores 
studied. Neither the oidia nor the chlamydospores resisted drying 
nor alternate wetting and drying. 

The oidia of Lenzites sepiaria and L. trabea are essentially sticky 
and were found not to be adapted to dissemination by air currents. 
They are, however, adapted to dissemination by insects and water. 
This adaptation may possibly be of some importance in case oidia 
are found to produce naturally in mills. Thus far, however, the only 
secondary spores of these fungi found in mills are the chlamydospores 
of Lentinus lepideus upon the fruit bodies. 


’ 


LY oy aetay iy he st eth ote « re ad 


ils Sdties! korg ARATN |p iter 
Lei] Pint i i GUE Th Te uit ito fhrte: wet Eth & Ate ote ital 


‘4 


Se 4 


Here hhh Dine Hae toby ora HOE O JooHa on 
PPLE AIRY SUE AY EY ee pele 4 5 be Mt a 
oti Kip EKinjis Pet (- Baaiihy 2: HD “royal (Py) ans 4on thew “aly is 

rece die ST BEL ete: iy bitte Whi idee 
Ri: rte MILs! bereits) it a ok A Anna! Mah an 


: SOP IN AE es ve cal Ppeee fi: sis ai a Yoni adh oh aes 


4 


Un Ue 7 he etg 


: tf ra Wa eet Le! ona Ph nn Tp gar ere Dnt sith a 
3 eh a sted ABP att Hor 


4 ————__ 


' , we} LP eos a 


seh iat 
: he Ly 
. } bas eve 
/ 
% ee 


LITERATURE CITED. 


tf.) Bram, R. J. 
1919. Fungi: which decay weave shed roofs. (Abstract.) In Phyto- 
pathology, v. 9, no. 1, p. 54-55. 


(2) 1920. Prevention of decay in the timber of pulp and paper mill roofs. 
In Pulp and Paper Mag., vy. 18, no. 1, p. 7-10; no. 2, p. 27-30. 
12 fig. 


(3) Bouprer, EMite. 
1887. Description de deux nouvelles espéces de Ptychogaster et nou 
velle preuve de lidentité de ce genre avec les Polyporus. In 
Jour. Bot. [Paris], t. 1, no. 1, p. 7-12, 1 col. pl. 


(4) 1887. Note sur une forme conidifére curieuse du Polyporus biennis 
Bull. In Bul. Soc. Mycol. France, t. 4, fase. 1, p. lv—lix, pl. 3 
(col.). 


(5) BREFELD, OSCAR. 
1889. Untersuchungen aus dem Gesammtgebiete der Mykologie. Fort- 
setzung der Schimmel- und Hefenpilze. Heft 8. Leipzig. 
(6) Butter, A. H. REGINALD. 
1905. The reactions of the fruit-bodies of Lentinus lepideus Fr., to 
external stimuli. Jn Ann. Bot., v. 19, no. 75, p. 428-439, 
pl. 28-25. 
(7) 1905. The destruction of wooden paving blocks by the fungus Len- 
tinus lepideus Fr. Jn Jour. Econ. Biol., v. 1, no. 1, p. 2-18, 
pl. 1-2. 
(8) 1908. Researches on fungi. An Account of the Production, Liberation, 
and Dispersion of the Spores of Hymenomycetes Treated 
Botanically and Physically. Also some Observations upon 
the Discharge and Dispersion of the Spores of Ascomycetes 
and of Pilobolus. xi, 274 p., 83 fig.,5 pl. London, New York, 
etc. 
(9) Burt, Epwarp ANGUs. 
1918. The Thelephoracee of North America. IX. Aleurodiscus. In 
' Ann. Mo. Bot. Gard., v. 5, no. 3, p. 177-208, 14 fig. 
(10) Coon, CATHARINE. 
1912. Beitrige zur Kenntniss der Sporenkeimung und Reinkultur der 
i hoheren Pilze. In Meded. Phytopath. Lab. Willie Commelin 
Scholten, III, p. 5-88, 45-46, 4 pl. Ubersicht der Litteratur, 
p. 37-38. 
11) EICHELBAUM, FELIx. 
~-1886. Uber Conidienbildung bei Hymenomyceten. Jn Bot. Centbl., 
nt Bd. 25, no. 8, p. 256-259, 1 fig. 
12) Erpam, Epuarp. 
1876. Die Keimung der Sporen und die Entstehung der Fruchtkorper 
bei den Nidularieen. Jn Beitr. Biol. Pflanz., Bd. 2, Heft 2, 
D. 221.248, pl. 10. . | | 


43 


44 BULLETIN 1053, U. S. DEPARTMENT OF AGRICULTURE, 


(18) FatcK, RICHARD. q 
1902. Die Cultur der Oidien und ihre. Riickfiihrung in die héhere 
Fruchtform bei den Basidiomyceten. Jn Beitr. Biol. Pflanz., 
Bd. 8, Heft 3, p. 307-346, 1 fig., pl. 12-17. 
(14) 1904. Die Sporenverbreitung bei den Basidiomyceten und der bio- — 
logischen Wert der Basidie. Jn Beitr. Biol. Pflanz., Bd. 9, 
Heft 1, p. 1-82, 2 fig., pl. 1-6. 
(15) 1909. Die Lenzites-Faule des Coniferenholzes, eine auf kultureller | 
Grundlage bearbeitete Monograph’e der Coniferenholz bewohn- — 
enden Lenzites-Arten. Jn Moller, A. Hausschwammforschung- 
en in amtlichem Auftrage, Heft 3, p. ix—xxwxii, 1-234, 24 fig. 
(138 col.), 9 pl. (partly col.). Jena. 


(16) © 1912. Die Meruliusfaiule des Bauholzes. Neue Untersuchungen iiber — 
Unterscheidung, Verbreitung, Entstehung und Bekaimpfung 
des echten Hausschwammes. Jn Moller, A. Hausschwamm- 
forschungen in amtlichem Auftrage, Heft 6, xvi, 405 p., 73 fig., 
17 pl. (partly ecol., 18, 17 fold.). Jena. 

(17) 1916. Zersté6rung des Holzes durch Holzschadlinge. 1. Pilze. In 
Troschel, Ernst. Handbuch der Holzkonservierung, Teil 1, p. 
46-147, fig. 28-82h. Berlin. 

(18) T6A0LL, J. Te 

1917. Fomes officinalis Vill.. a timber-destroying fungus. In Trans. 
Roy. Canad. Inst., v. 11, pt. 2, no. 26, p. 185-209, 1 fig., pl. — 
18-25. Literature cited, p. 207-208. 
(19) FrerGuson, MARGARET C. 
1902. A preliminary study of the germination of the spores of Agaricus — 
campestris and other basidiomycetous fungi. U. S. Dept. sf 
Agr., Bur. Plant Indus. Bul. 16, 48 p., 3 pl. Bibliography, % 
p. 389-40. 
(20) Hitry, W. E. | 
1919. The Fungal Diseases of the Common Larch. xi, 204 p., 73 fig. 
(in text and on 21 pl.). Oxford (England). Bibliography, 
p. 193-199. 

(21) HoFFMANN, HERMANN. 

1860. Untersuchungen iiber die Keimung der Pilzsporen. In Jahrb. 
Wiss. Bot. [Pringshe:m], Bd. 2, p. 267-337, pl. 26-32. 

(22) Horson, JOHN WILLIAM. 

1912. Culture studies of fungi producing bulbils and similar propa- — 
gative bodies. Jn Proc. Amer. Acad. Arts and Sci., v. 48, no. 8, | 
p. 227-306. 12 pl. Literature, p. 303-306. . 


(23) 1917. Notes on bulbiferous fungi with a key to described species. In 
Bot. Gaz., v. 64, no. 4, p. 265-284, 6 fig., pl. 21-23. Literature 

cited, p. 288. 

(24) Hoxisz, F. J. 
1915. Dry Rot in Factory Timbers. Ed. 2. 107 p., 70 fig. Boston. 
(Inspection Dept. Associated Factory Mutual Fire Insurance 

Companies, [Publ.] No. 32.) x 


(25) HwtusBarD, HENrRY G. 
-1892. The inhabitants of a fungus. Jn Canad. Ent., v. 24, no. 10 
p. 250-255. 


FUNGI OF IMPORTANCE IN THE DECAY OF TIMBERS. 45 


(26) JACZEWSKI, ARTHUR DE. 
1910. Note sur le géotropisme et le phototropisme chez les champig- 
nons. In Bul. Soc. Mycol. France, t. 26, fase. 4, p. 404408, 
6 fig. : 


(27) KeirTr, G. W. 
1915. Simple technique for isolating single-spore strains of certain 
types of fungi. Jn Phytopathology, vy. 5, no. 5, p. 266—269, 
1 fig. 
(28)_ Learn, C. D. : 
1912. Studies on Pleurotus ostreatus Jacqu. and Pleurotus ulmarius 
? Bull. Jn Ann. Mycol. v. 10, no. 6, p. 542-556, pl. 16-18. 
Bibliography, p. 552-554. 


(29) Lone, W. H., and Harscu, R. M. 
1918. Pure cultures of wood-rotting fungi on artificial media. In 
Jour. Agr. Research, v. 12, no. 2, p. 338-82. Literature cited, 
p. 81-82. 


(30) Lupwic, FRIEDRICH. 
1880. Ptychogaster albus Corda, die Conidiengeneration von Polyporus 
Ptychogaster n. sp. Jn Ztschr. Gesam. Naturw., Bd. 53, (Fols. 
3, Bd. 5), p. 424481, pl. 13-14. 


(31) LYMAN, GEORGE RICHARD. 
1907. Culture studies on polymorphism of Hymenomycetes. Jn Proc. 
Boston Soc. Nat. Hist., v. 33, no. 4, p. 125-209, pl. 18-26. 
Literature, p. 203-209. 


(82) MarryaT, DoroTHEA C. E. 
1908. Chlamydospore-formation in the basidiomycete Pleurotus sub- 
palmatus. In New Phytol., v. 7, no. 1, p. 17-22, 1 fig., pl. i. 
(33) MASSEE, GEORGE. 
1889-90. A monograph of the Thelephoreae. Jn Jour. Linn. Soe. 
[London], Bot., v. 25, no. 170, p. 107-155, pl. 45-47, 1889; v. 
27, no. 181-182, p. 95-204, pi. 5-7, 1890. 


(34) Matrucnuor, Louis. 
1897. Recherches biologiques sur les champignons. Jn Rey. Gén. Bot., 
t. 9, no. 99, p. 81-102, fig. 16-34, pl. 4. 


(35) Mrz, CARL. 
1908. Der Hausschwamm und die tibrigen holzzerst6renden Pilze der 
menschlichen Wohnungen. Ihre Erkennung, Bedeutung und 
Bekimpfung. 7, 260 p., 90 fig., 1 col. pl. Dresden. Nachweis 
der im Buch zitierten Literatur, p. 250-254. 
(86) MOLLER, ALFRED. 
1907. Hausschwammuntersuchungen. In his Hausschwammforschungen 
in amtlichem Auftrage, Heft 1, p. 29-52, pl. 1-5. Jena. 
(37) MUNcH, Ernst. 
1909. Uber die Lebensweise des “ Winterpilzes,’ Collybia velutipes 
Curt. Jn Naturw. Ztschr. Land u. Forstw., Jahrg. 7, Heft 12, 
p. 569-577, 3 fig. 


_ (38) Murriny, W. A. 
1915. Agaricales. Agaricaces. 26. Lentodium Morgan. Jn No. Amer. 
Flora, v. 9, pt. 4, p. 296. New York. 


46 BULLETIN 1053, U. S. DEPARTMENT OF AGRICULTURE. 


(39) PATOUILLARD, NARCISSE. Rd 

1881. Sur quelques modes nouveaux ou peu connus de reproduction 

secondaire chez les hyménomycétes. Jn Rev. Mycol., Ann. — 

3,,no, 10, p. 10-12)p1,16, Best. a 

(40) 1882. Observations sur quelques hyménomycétes (Cyphella curreyi, i 

Trametes rubescens, Agaricus spissus). Jn Rey. Mycol., Ann. F 

4, no. 18, p. 35-38. \ 

(41) 18838. Quelques observations sur Vhyménium des basidionrycétes. In 
Rev. Mycol., Ann. 5, no. 18, p. 167. 


(42) 1885. Contribution 4 l’étude des formes conidiales des hyménomycétes: | 
Ptychogaster aurantiacus Pat. sp. nov. In Rev. Mycol., Ann. | 
7, no. 25, p. 28-29. 


(43) 1887. Hyménomycétes d’Europe. Anatomie générale et classification ‘ 
des champignons supérieurs. 7, 166 p., 4 pl. Paris. (Maté- 
riaux pour Vhistorie des champignons, t. 1.) 


(44) 1890. Les conidies du Solenia anomala. In Bul. Soc. Mycol. France, 
t. 5, fase. 4, p. 128-129. 


(45) 1891. Polyporus bambusinus, nouveau polypore conidifére. Jn Bul. 
Soe. Mycol. France, t. 7, p. 101-108. 


(46) 1894. Espéces critiques d’hyménomycétes. Jn Bul. Soc. Mycol. France, 
t: 10, p. 75-61, 2 fe, pia: 
(47) RHoADS, ARTHUR S. 
1918. The biology of Polyporus pargamenus Fries. N. Y. State Col. 
Forestry Tech. Pub. 11, 197 p., 31 pl., 6 fig. Syracuse, N. Y. 
Literature cited, p. 194-197. (Syracuse Univ. [Bul.] v. 18, 
no. 5.) 


(48) RicHoN, CHARLES. 
1877. Notes sur trois espéces intéressantes de champignons. Corticium 
amorphum, Ptychogaster albus, Pilacre poricola. Jn Bul. Soc. 
Bot. France, t. 24, p. 148-152, 6 fig. 


(49) RuMBOLD, CAROLINE. 
1908. Beitrage zur Kenntniss der Biologie holzzerstérender Pilze. In 
Naturw. Ztschr. Forst. u. Landw., Jahrg. 6, Heft 2, p. 81-140, 
26 fig., 1 col. pl. Literatur, p. 139-140. 


(50) SErYNEs, J. DE. 
1874-88. Recherches pour servir 4 l’histoire naturelle des végétaux 
inférieurs. 3 fasc., 16 pl. (partly col.) Paris. 


iv) 


(51) 1884. Les conidies mycéliennes du Polyporus sulfureus Bull. Jn Bul. 
Soc. Bot. France, t. 31 (sér 2, t. 6), p. 296-299. 

(52) 1890. De la distribution des Ceriomyces dans la classification des 
polyporés. Jn Bul. Soc. Bot. France, t. 87 (sér. 2, t. 12), p. 
109-112. | 


(53) 1891. Conidies de ’Hydnum coralloides Scop. In Bul. Soc. Mycol. 
France, t. 7, p. 76-80, 1 fig. 
(54) 1893. Un Ptychogaster du Congo. Jn Bul. Soc. Bot. France, t. 40 (sér. : 
2, v. 15), p. Ixxxiv—-Ixxxvi. 
(55) SNELL, W. H. 
1921. Chlamydospores of Fomes officinalis in nature. /n Phytopathol- 
ogy, v. 11, no. 4, p. 173-175, 1 fig. 


(56) 


(87) 


(58) 


(59) 


(60) 


(61) 


(62) 


(63) 


FUNGI OF IMPORTANCE IN THE DECAY OF TIMBERS. 47 


SPAULDING, PERLEY. \ 
1904. Two fungi growing in holes made by wood- pas athe In 
Mo. Bot. Gard. 15th Ann Rpt., p. 73-77, pl. 25-27. 
1905. A disease of black oaks caused by Polyporus obtusus Berk. In 
Mo. Bot. Gard. 16th Ann. Rpt., p. 109-116, pl. 13-19. 
1911. The timber rot caused by Lenzites sepiaria. U.S. Dept. Agr., | 
Bur. Plant Indus. Bul. 214, 46 p., 3 fig., 4 pl. Literature, p. 
31-37. 
STEFAN, JOSEPH. 
1905. Beitrag zur Kenntniss von Collybia racemosa Pers. In Hed- 
wigia, Bd. 44, Heft 3, p. 158-167, pl. 5. 
TUBEUF, CARL VON. 
1903. Hausschwamm-Fragen. In Naturw. Ztschr. Land u. Forstw., 
Jahrg. 1, Heft 3, p. 89-104. 
WEHMER, CARL. 
1912. Hausschwammstudien. I. Zur Biologie von Coniphora cerebella 
A. et Sch. In Mycol. Centlbl., Bd. 1, Heft 1, p. 2-10, 4 fig. 


WEIR, JAMES R. 
1914. Notes on wood destroying fungi which grow on both coniferous 
and deciduous trees. I. In Phytopathology, v. 4, no. 4, p. 
272-276. 


ZELLER, SANFORD M. 
1915. Notes on Cryptoporus volvatus. In Mycologia, v. 7, no. 3, p. 121- 
125, 1 fig., pl. 159. Literature cited, p. 125. 


O 


‘pager Neh ber ye 7 


gf dah zrrampuok edt t Pre Skier inte * 
Se LLL kr eee sit \ dit. vir ay 
j AU pie We ORR ad ‘set ra it “ochitht it 
; De = 4 Leb 4 e 
a" ey > oe |e & 4 a Wt Rs i et wap bask 3 fa at UE 
} . 


k ae ih tReet Gina my 


at Hele Hk Ne MO 


 TaAas iy Rie es ee 1S sae a aia 


th 2 | 


ah Ald QA CRLOG A tht hee canst A tte 


; i } EREEC On Ce ao | 
‘ M 
j ee: ye " i 
role (Tl TROTIPSD DUO tig: 


t " ‘ MenTTRNOTTA: ¥) Pe sh aes a 


Wi, ah: 
b 30) ara Ne mt alee iF are pg a 


: ; : x Se a aal, S| 
- ; » bee 4 } rt rt) 
j 3 : gem te ean ‘ mae ey 5 a 
= ‘ rT ¥ 
* , at , ie 
‘ae 
‘ 
1 
woul 
yt ook 
d ‘ 
44° 
PRLS 
, 
F / 4 
‘ 
y 
Py 
i, Ae 
4 
( 
\ 
\ 
{ 
+ 
5 1 > 
nce - 
of pal , } 
a_i 
Laue 
fF +e ‘ 
’ 
7 4 
{ { 
¥ 
iq 
= “a 
i 
‘ 
iy ‘ fe . 
? i fi 
i . oe 
{ 
: ye 
/ ; 
‘ 
t 
- 
‘ A 
A 
pas 
a i* 
i ; Ny 
a4 TN 
“ v ‘\ 


Washington, D. C. Vv December 21, 1922 


THE WESTERN YELLOW PINE MISTLETOE: 


Effect on Growth and Suggestions for Control. 


‘By Cxiarence F. Korstian, Forest Examiner, Appalachian Forest Experiment Station, 
Forest Service, and W. H. Lone, Forest Pathologist, Office of Investigations in 
Forest Pathology, Bureau of Plant Maltiaatby’ 


CONTENTS. 
Page 
BEPIULOCUCTHION. ooo 8 ee eee ee nee ee ee ce enn comet e nee n gee cenccen eirces: 1 
ncn) amc Climeatieipatures)of the region: . 4.24: . 52204-2435). fos ssh ek Oo ede lo eked 2 
een IIA MEU EMELG IIMSUIOLOG <2 250 2. oon. 8 Fe 2 oes oe we ne wae ee Ss oe ngewe Pac annye wens 3 
nnn ne ErOWell OF NOB. S022 ooo os So ee ciaten c= <n cnt ecewedciecegpeccceececns 4 
Sumremnrenvan® 0 DORE CEC). trees aed. 945 J. 242 - LT. - TREE EELS eh ey. ee de. 2 22 
Effect of mistletoe on merchantibility of timber. ...- Pec ee ted Grapher Se’ hata 4, dechnce coke 25 
Bateer weaietioLoe o1,seed production of host... oo. ooo so ee etn eee este cere ceencs ‘a 25 
Silvicuitural aspect of mistletoe infection.....225/.. 2.2.0.2 false econ lee ebb eee dee eens 29 
Ye BB eo ale wo boo ie Se whos Si iwin nn Page he ileig ce pa ghee aes haces boPe ee ss scuitges 30 
EG Fa Doe 2. oh Doc's ak i eae a faa = o's am a tale spine sp aise cee Sean tesa gee ewseacunpes 34 
INTRODUCTION. 


Western yellow pine (Pinus ponderosa Laws.) occurs naturally 
from southern British Columbia to northern Mexico and from the 
Pacific coast to east of the one hundredth meridian. It is found in 
the forests of every State west of the Great Plains and in many of 
hem it is one of the most important and valuable forest trees. In 
the Southwest, western yellow pine is by far the most important 
timber tree, constituting over 80 per cent of the commercial forests of 
Arizona and New Mexico, approximately 30 billion board feet. 

_ During the past 12 years studies have been in progress to deter- 
I ine the effect of the mistletoe (Razowmofskya cryptopoda (Engelm. ) 
Cov.) on the growth and seed production of western yellow pine. 
This: parasite is the most widely distributed and one of the most 
' N NOTE .—The author’s names are in alphabetical order. The writers are indebted to Silviculturist G. A. 
arson, of the Fort Valley Experiment Station, for the permanent sample-plot data contained in Tables 
and 17, for the data on the 1915 seed collection contained in Table 18, and for his general interest in the 
my estigation. 

——— 3600°—22—Bull. 1112—1 


2 BULLETIN 1112, U. S. DEPARTMENT OF AGRICULTURE. 


serious enemies of the western yellow pine, and it has confronted the 
forester from the beginning of silvicultural practice in the Southwest. | 
Especially on southern exposures and near the lower limit of the type, _ 
areas may be found on which fully 75 to 90 per cent of all the trees 
above 6 inches in diameter are infected with mistletoe. “et 
In marking western yellow pine, there is often a question as to 
the advisability of cutting trees of various ages and degrees of mis- 
tletoe infection, or of allowing them to remain as seed trees and form 
a part of the future stand which will provide the basis for a subsequent 
cut. This problem involves not only a study of the effect of mistletoe 
on the rate of growth and the longevity of its host, but also of the 
effect of the parasitism on the amount and periodicity of seed pro- 
duction. 


PHYSICAL AND CLIMATIC FEATURES OF THE REGION. | 


The areas in which the intensive studies were conducted lie within 
the Coconino and Tusayan National Forests on the Colorado Plateau, 
near the San Francisco Mountains in northern Arizona. The general 
topography of the plateau is rolling and consists of alternating flats 
comparatively free from rock and of rather low ridges which are very 
rocky. The underlying rock of the plateau consists principally of 
Coconino sandstone and Kaibab limestone overlaid by a lava flow of 
basalt and acidic volcanic rocks, mainly dacite, andesite, rhyolite, 
and latite, which constitute the main outcrops and surface rocks of 
the region. The soil varies widely from a fine sandy loam to a red- 
dish friable clay, often containing an admixture of gravel and large 
volcanic bowlders. In the greater part of the region northeast of the — 
' San Francisco Mountains the soil is covered with black volcanic — 
cinders to depths varying from one-half inch to about 18 inches. — 
Mistletoe infection is rare on these cinder areas and where found at: 
allis light. The level mesas and lower slopes of the plateau, ranging 
from approximately 6,500 to 8,500 feet in elevation, are covered with 
a forest, of which approximately 95 per cent is western yellow pine, 
constituting the most extensive forest of this species in North © 
America. ) eg 

The climate of that portion of the Colorado Plateau which is — 
covered with a western yellow pine forest is indicated by the climato- — 
logical data which have been secured at the Fort Valley Forest 
Experiment Station. Pearson’s + studies in this locality, together — 
with the records of the United States Weather Bureau throughout 
the region, have shown that the climate is characterized by marked 
seasonal variations in precipitation, atmospheric humidity, and — 


1 Pearson, G. A. A Meteorological Study of Parks and Timbered Areas in the Western Yellow Pine 
Forests of Arizona and New Mexico. Monthly Weather Review, vol. 41: 1615-1629, 1914. 


THE WESTERN YELLOW PINE MISTLETOE. 3 


‘wind movement, and great daily ranges of atmospheric temperature. 
The amount of sunshine is unusually high. The mean annual pre- 
cipitation in the western yellow pine forest amounts to between 20 
and 25 inches, which occurs in two well-defined periods during July 
and August in the form of thundershowers and from November to 
April in the form of snow. The period from about April 15.to July 
15 is characterized by desiccating southwest winds and excessive 
evaporation, which, together with the small amount of precipitation, 
produce conditions adverse to most types of vegetation. The high 
rate of evaporation, low atmospheric humidity, and high wind 
velocity very often cause excessive transpiration from plants. The 
climatic and soil conditions are such that nowhere within the western 
yellow pine type of the Southwest does this species make rapid 
eorowth. 
The influence of such climatological conditions is generally con- 
sidered unfavorable to the best development of the host and favorable 
to the distribution and growth of the parasitic mistletoe. Weir ? 
has emphasized the fact that the ecological relationships of the 
nistletoes, although they are parasitic, are similar to those of other 
Re hyHaceous plants in that they also respond to light, gravity, 
and certain chemical stimuli, while the marked variations in tempera- 
ture to which the host readily responds are only slightly effective on 
‘the parasite. The low atmospheric humidity has a very slight 
:. uence on the xerophytic mistletoe, while the great amount of 
sunshine is favorable to the parasite. The unusually high winds of 
the Southwest frequently cause rather serious losses to western 
yellow pine stands in exposed situations through windfall, and the 
_ wind is known to aid in the dissemination of the mistletoe seed from 
tree to tree. 
_ It follows that, where a virulent parasite responds favorably to its 
habitat, the host will rapidly deteriorate on the more unfavorable 
‘sites. From numerous observations made in various parts of the 
Southwest, it is apparent that a rather definite relation exists 
between the unfavorableness of the site and the degree of mistletoe — 
infection. The percentage of infection and the resulting mortality 
of the host is usually higher on exposed dry ridges and south slopes 
phe n on the more favorable sites. This condition is very apparent 
m the Santa Fe National Forest in yg New Mexico. 


= THE WESTERN YELLOW PINE MISTLETOE. 


The family Loranthacex hag 
Ph eeron and Razoum¢ 
ee on both hard 


two genera in the United States, 
skya. The species of Phoradendron 
foods and conifers, but mainly on hard- 


se R. The Larch Mistle 


r Ss yd 317, pp. 5-10, 1916. 


5: Some Economic Considerations of Its Injurious Effects. U.S. 


a: 
rif 


4 —- BULLETIN 1112, U. S. DEPARTMENT OF AGRICULTURE. 


woods, while the genus Razoumofskya is found exclusively on | 
conifers. Several species of the latter genus are rather common in 
the western United States and in some localities have become very ~ 
serious parasites. Razoumofskya cryptopoda, the western yellow 
pine mistletoe, is one of the most widely distributed of all the species, 
usually being found wherever the western yellow pine grows. 
(Plvd;-Fig. 1.) 
iarcihneapelevei cryptopoda flowers in ‘eibioey and New Mexico — 
during April and May, and the fruit matures in August and Septem- 
ber of the next year. When the seeds begin to ripen, the berries © 
gradually turn downward on their pedicels until the base of each ~ 
berry when fully mature points upward. The gelatinous seeds when ~ 
ripe are suddenly and forcibly ejected upward to a distance of several ~ 
yards by the giving way of a ring of tissue situated near the base of © 
theberry. Thismethod ofseed dissemination is common to allspecies — 
of Razoumofskya. Experiments and extended observations indicate ~ 
that the aerial portions of both staminate and pistillate plants die ” 
and fall from the trees after one season of floweymg and cae 
(Pl. I, Fig. 2.) 


EFFECT OF MISTLETOE ON GROWTH OF HOST. 


The study of the effect of mistletoe on its host was accomplished ~ 
(1) by periodic measurements and observations of standing trees, ~ 
both infected and healthy; and (2) by detailed growth whstinin9 and 
observations of infected and healthy felled trees. 


EFFECT ON BOLE OF TREE. 


Ninety-one healthy and mistletoe-infected trees between 10 and ~ 
30 inches in diameter breast high on three different areas within a ~ 
radius of 5 miles of the Fort Valley Experiment Station were tagged, 
numbered, measured, and mapped in 1910 with the object of deter-— 
mining the effect of mistletoe on the diameter and height-growth of © 
the host, the diameter growth of limbs, and the growth of the mer-" 
chantable contents of the bole. The diameters were measured with — 
a diameter tape at 1, 4.5, 17, and 33 feet above the ground. The 
total heights were measured with a Forest Service standard hypso- 
meter. The diameters of 20 healthy and 34 mistletoe-infected 
limbs falling in different infection classes were measured on 18” 
standing trees with a view of determining the effect of mistletoe 
on the growth of, limbs. The points of measurement at 6 inches” 
from the bole of the tree and every 6 inches beyond this point were 
marked by driving a 6-penny copper nail into the wood. All of the 
trees were remeasured in 1915 and were reclassified into four degrees 
of mistletoe infection, according to the prevalence of mistletoe on 
the tree, as follows: O, healthy trees without Tasers x, lig at 


PLATE 


U. S. Dept. of Agriculture. 


1112 


Bul. 


‘UOISO] 9} JO espo Joddn oy) 1B syueytd 903 


-O[JSTUL SNOIOSTA ‘SUNOA PUP JO}UID OY} UL WOTJOeJUT ATIVE JO SUIOJS Pvop 


‘autd MOT[eA U1oJSOM Jo 


SIM} & UO UOTSO[ 90JOTISTUL B JO VOUBAPY—'Z “DIA 


SuIo}s OL 


fs /UOISET 94 JO pUs Yoo 4v Uses 01” syuRTd 
qsosunod oY} pUv Jo}UAd OY} UI o1B syuL[d 90JoT}STUL SUTAP PUB pRep JO 
‘ourd MoT[eA U104SOM MO AUOTOO 904o7}STUL [VoIdAY W—'T “DLT. 


j 


THE WESTERN YELLOW PINE MISTLETOE. 5 


_ mistletoe infection; XX, medium mistletoe infection; XXX, heavy 
- mistletoe infection. © 

In order to check any material effect that the different crown 
classes might have on the rate of growth the trees were also classified, 
_ according to their dominance or relative position in the crown canopy 


of the group, into the following crown classes: - 


_ Isolated.—Trees growing in the open which do not form a contig- 
_ uous part of the regular group canopy. 
- Dominant.—Trees with crowns extending above the general level 
of the group canopy and receiving full light from above and partl 
from the side; larger than the average trees m the group, and wit 
crowns well developed but possibly somewhat crowded. 
Codominant.—Trees with crowns forming the general level of the 
oup canopy and receiving full light from above, but comparatively 
little from the sides; usually with medium-sized crowns more or less 
- crowded on the sides. 
Intermediate—Trees with crowns below, but still extending into 
the general level of the group canopy, receiving a little direct light 
from above but none from the sides, usually with small crowns 
- considerably crowded on the sides. 
_ Suppressed—Trees with crowns below the general level of the 
roup canopy and receiving no direct light either from above or 
rom the sides; usually with small, poorly developed crowns. 


_ There are two well-recognized forms of Pinus ponderosa, “black 
jack” and ‘‘yellow pine,’ based on age, rate of growth, and the 
resulting color of the bark. The term “black jack” applies to the 
_ young, vigorous trees under 125 to 150 years old which are charac- 
_ terized by a dark, almost black, or dark brown, narrow-furrowed 
bark. The “yellow pine” form comprises the older trees, which are 
characterized by a yellowish or reddish brown, widely furrowed bark. 
There is a marked difference in the form and volume of black jacks 
and yellow pines. The average black jack has a greater taper, a 
more rapid rate of growth, and approximately 10 per cent smaller 
cubic volume than the average yellow pine of the same diameter 
_and height, which were the chief reasons for the segregation of black 
_ jacks and yellow pines. 
_ The mean diameter growth or accretion of the standing black jacks 
for the 5-year period from 1910 to 1915, grouped according to degree 
of mistletoe infection, is shown in Table 1. The diameters were 
averaged by infection classes for each year mentioned, and the 
difference was computed as the growth during the 5-year period or 
the periodic accretion. The average growth per year during the 
period considered is termed the periodic annual accretion. The data 
_ show an almost consistent decrease in the diameter growth of black 
_ jack with the degree of mistletoe infection. The slight inconsistency 
_ exhibited in the rate of diameter growth of the o and « infection 


6 BULLETIN 1112, U. S. DEPARTMENT OF AGRICULTURE, 


classes might be explained by the fact that of the 27 trees in dia 
infection class, 11 per cent were isolated trees which did not form a 
part of the forest canopy, 28 per cent were dominant, 57 per cent 
were codominant, and 4 per cent were intermediate trees, while 
with the z infection class 60 per cent were isolated trees which did 
not form a part of the forest canopy and 40 per cent were in the 
codominant crown class. Table 2 consistently shows a decrease in 
the rate of diameter growth of yellow pine which varies directly | 
with the degree of mistletoe infection. 


TABLE 1. —Comparison of the average diameter growth or accretion of 58 standing black 
jacks, for a 5-year period, grouped according to degree of mistletoe infection. 


Diameter breast-high. | Accretion, 1910-1915. 


Degree of inf&tion. Basis. 
1910 1915 Periodic. | Feriodic 
Inches. Inches. Inches Inch Trees 
On FEF Fo. BSAA. SAE he ae . 16 16. a 
Rae re Ge eS i Me Si Se ed igeeed 17.65 18.63 é 
DO. Sa ae STN een Pe RU ee AINE cae ONE RS 15. 82 16. 57 Py #3 Pe it 


até 4. lawGl: Letariows. OK oie 14. 24 14, 36 112 102 


TABLE 2.—Comparison of the average diameter growth or accretion of 38 standing yellow 
pines, for a 5-year period, grouped according to degree of mistletoe infection. | 


Diameter breast-high. | Accretion, 1910-1915. 


Degree ofinfection. — a Basis. 
. eriodic 
1910 1915 Periodic. annual. 
Inches. Inches. Inch. Inch. Trees. 
OE nich BS ae teenth dae oa det eaters cae tee ae 24.60 25. 30 0.70 . 14 : 
ener ees ae cia ee en ae oe eS 25. 56 26. 04 48 .10 
1.2, Gap es ened de OS Serer ae Se, Samy, oo WIE ew 9 22.14 22. 44 . 30 06 


PS, Hee ee. peer were eer ee 21. 49 21.61 12 «Ge 
1 Five trees of this class died during the 5-year period and were not included in the computation. 


TaBLE 3.—Comparison of total volume growth or increment of 58 standing black jacks, 
Wet a 5-year period, grouped according to degree of mistletoe infection. 


Total volume. Increment, 1910-1915. 


Degree of infection. : 
1910 1915 Periodic. Periodic annual. 


Cubic feet. | Cubic feet. | Cubic feet. | Cubic feet. | Per cent. ‘Trees. si 
987.2| 1,100.9 113.7 22.7 2.30) soa 


EES = ne Se <a eS 

ss Taculeee te eteie),. abs -291. 4 ” 304.4 33.0 6.6] 2.26 
BO Bo Se, 434. 0 470.6 36.6 7.3 1.68 
5.2.0. a REE te 5 ts Bee = ee ee Ao 234. 9 243. 2 8.3 iy. i722 


THE WESTERN YELLOW PINE MISTLETOE. 7 


TaBLE 4.—Comparison of the total volume growth or increment of 83 standing yellow 
pines, for a 5-year period, grouped according to degree of mistletoe infection. 


Total volume. Increment, 1910-1915. 
Degree of infection. ee ———— ooo |» »- Baas. 
1910 1915 Periodic. Periodic annual. 


Cubic feet. | Cubic feet. | Cubic feet. | Cubic feet. | Per cent. Trees. 
51. 1, 226. 0 75.0 1 1.30 


Mena 0) SOFAS TT 0. 1, 151.0 , 226. 5.0 9 
OS ee 1,206.0] 1,250.0 44.0 8.8 .73 8 
Mpsiie. fuse neil! Oly 706. 0 725.0 - 19.0 3.8 154 7 
Sb Sere 801.0 809. 0 8.0 1.6 20 19 


1 Five trees of this class died during the 5-year period and were not included in the computation. 


Table 3 shows the total volume growth or increment of the stand- 
ing black jacks for the same 5-year period, grouped by infection 
classes. The total volumes were computed by applying a volume table 
based on diameter and total height to the dimensions of each tree as 
measured in 1910 and 1915. It was found from taper measurements 
that volume tables could safely be applied to the individual trees. 
The volumes of all trees were totaled by infection classes. The differ- 
ence between the total volumes at each time of measurement repre- 
sents the periodic increment, and the average volume growth per 
year during the period considered is the periodic annual increment. 
Table 4 shows the increment of the standing yellow pines for the 
same 5-year period. Both forms of western yellow pine exhibit a 
consistent decrease in the increment of those trees which are infected 
with mistletoe varying directly with the degree of infection. 

Bole measurements were made at 16-foot intervals to insure greater 
accuracy in the study of the effect of mistletoe on the growth of the 
merchantable contents of the bole of the tree. Table 5 gives a compar- 
ison of the diameter growth of the bole of 33 trees at 4.5, 17, and 33 
feet above the ground. The comparative increments of the same 
trees are shown in Table 6. The apparent discrepancy between the 
rate of growth of the uninfected and lightly infected classes, as was 
noted above, is apparently due either to the varying proportions of 
the trees among the different crown classes or it may be possible that 
the infection at first results in a slight stimulation of the tree. In 
computing the volume, each section below the highest point of meas- 
urement was cubed as a cylinder by averaging the basal areas of the 
_ ends and multiplying by the length of the section;? that portion above 
_ was considered as the top of the tree and its volume was computed as 


that of a cone. 


The growth of the standing trees was further checked by complete 


4 stem analysis of 102 felled trees. Sections were examined as near 
_ to the surface of the ground as possible, at 4.5 feet above the ground, 


8 This is known as the Smalian method. See Graves, Henry S., Forest Mensuration, pp. 91-93, New 


York, 1907. 


8 BULLETIN 1112, U. S. DEPARTMENT OF AGRICULTURE. 


and at every 8 feet above this pomt. The measurements were 
recorded by 5-year periods instead of by decades, as is the usual prac- 
tice in complete stem analysis. The trees were selected as nearly as 
possible from the same site, kind of stand, and the same age and 
crown classes. Only those trees free from abnormalities or other 
possible causes of deterioration or conditions deterrent to their 
growth were studied, thus permitting only two variables to enter 
into the results, the age of the tree and the degree of mistletoe infec- 
tion. The classification of the tree according to degree of infection 
represents the consensus of opinion of three different observers. 

The basic data for each of the individual felled trees which were 
analyzed to show the effect of mistletoe on the growth and seed pro- 
duction of western yellow pine have been arranged in Table 7, accord- 
ing to the age of the trees. In compiling the stem analyses the data 
for each tree were computed separately. The diameters and heights 
of each tree for each fifth year, dating back from the year of analysis, 
were correlated with age in growth-analysis diagrams, from which 
the dimensions of each tree for each integral 5 years of age or quin- 
quennium were read. 

TaBLE 5.—Comparison of the average diameter growth or accretion of 83 standing black 


jacks, for a 5-year period, at 4.5, 17, and 33 feet from ground, grouped according to 
degree of mistletoe infection. . 


Diameter outside bark. Accretion, 1911-1916. 
Degree of 1911 1916 Periodic. Periodic annual. akin 
infection. - 
a ORE ald eae Se ie lee b> ad De” WR cde 
feet. | feet. | feet. | feet. | feet. | feet. | feet. | feet. | feet. 
In. In. In. In. In. | In..| In| In. | Fn. 
re ee ee 15.28 | 12.69 | 19.03 | 16.30 | 13.71 | 1.10 | 1.02 | 1.02 | 0.22 
2, gt pes apne | 19.59 | 14.14 | 23.40 | 20.85 | 15.25 | 1.15 | 1.26] 1.11] .23 
RX. chicas bs 13.20 | 8.65 | 16.78 | 13.81 | 9.46] .86} .61] .81 |] .17 
2.9.6. Me Se FANE 14.42} 9.19 | 17.15 | 14.64} 9.31] .68| .22] .12] .14 


TABLE 6.—Comparison of the total volume growth or increment of 33 standing black 


jacks, for a 5-year period, grouped accordvng to degree of mistletoe infection. 


. 


Total volume. Increment, 1911-1916. 
Degree of infection. Basis. 
1911 1916 Periodic. Periodic annual. 

Cubic feet. | Cubic feet. | Cubic feet. | Cubic feet. | Per cent. Trees. 
Fe oo on ie est, Soe epee 919. 76 1, 047. 40 127. 64 25. 53 2. 78 16 
Ss as Re esate See eee 359. 07 410. 65 51. 58 4 
OR ee ae oe aaa eee 286. 83 316. 08 29. 25 7 
Se es Sey... oe areas 262. 65 273. 97 11,32 6 


for) os) 
= nf 
S SZ cas 

~ @RB 
Pa NOon OO000000 : 

S 8 ov Ooo0°0 

Botor : C000 
S & boas AONOO C0000 
: a®en8 Sgro OO OOD 69 69 =H COOON00 
= aS = = S wit 00.06 2D IND CDO CO Or: 
& @ tous © : ABOSed UdSododai nOoM Holelel=| 
° = EReSE Oa bebe etre Mgdadigvnnsqccsned ; GY cocese oe ‘ 
o s sid A qias (coho) me Pree Airvos) ; . ! 
= Ss 2 3/ we a at ios Ae Ae a cael : gt gta bee kad ee os — 0000 ino € fi 
; ies 161s S65 oO : Sr se se ‘ON tt 5 ; 

* ES: IID eN IN DOD rH AN OD re AD st HS mee ees (O00 +O & 

a B & 8 : 19 6318 S15 15 O19 ODO : ae Mad eS id od SNoa Oo A 
ys Os WOODDUAKA ; Gilead hae <td Gecrhae ie i Md [Sicdeegdee 3 I 
wT ‘ak + o7 OROKKK cot ONO op #09 6 OD CO CD10 Des 
125 CL ea te 19 60 

4 oS agses OHHOKAaM : Sod al had of cd ad Ate ea 2 a 
Q, aS) ° pab< . H 09 05 15 <i fad cS 4 a we 

a Bs As wootookookE KODUKKOONONKK Wucdees 2 8 ¢ 

@o e 4 OD o 

‘ a S $2 4 HExnoonmine 4 ROKMO” CS: ee 

—S he ba PS 4 bd bd 

7 vs oe had Cee Ron Romane! vy AOp,WOO a g 

» 2 =o7Le pin te ak = nn COMMS QANMOoO iS a 
al a) Conk> Bessnsas tn ‘ re ae cooky OOOKnN aed ee 
5 ™@e > bS 5 PEE Eh Cee ee eet ma Hinwoontoht ont , AoK % 8 i 

te 4: sd ices eters oD A enSraaas ‘ te bd id WKo bd id a 
te 28 Bad Begg ees oe Se HASIs i228 HAKOKOHME KH Mi sous 

‘Ss OD 56'S —______________ ‘SSSSSRLEK bd pd PS On. oO 4 2 O q 

See oO i ‘ — 
3 ss Br SeBRRAANSASEE ; ody eos sehrg ele bench HHOHHOOHHOK ace = 
= a USA pete SSSSESRERS CE Tae aonean ing SS88Ee : g8e | 

3 >> S82 See CS a aSeoam C25 ta on OHS RS | ‘ ae 
B §e eg | ysassces°s . SRESRSSS STRAT ARASH a SSESSE L agsnaes SBE g 

= S Hae a ene eS Spo shack NEKe a Niro (RASABSHS Ne} : so MON aN Ss oa 

3s S ive) HH ° saa 1D OO O19109O AAs Hos . 9 <O rete fiat acl lh mat eS ; Sag i 
7 dios as aoa a a sé Sissi “Grids nSESSSRR85 3 
os Re ; mini “od * 1SOOHOWN -2 GisssSswcios BZSSSSES3 FS is 

es Sb hak apes? * pode ed edad UD 119 D 1 SSSOARMN AWS 3 ROO MO ID 69 Ro | 
ica} om + os O1n219 1 tH ° moO eel Is ac é 19 OH > mo 
A 2&2 as S15 wi 0d 09 3 08 > 41D 19 ON .00 1 : Erg Bie hepa ereets ar wie ae ents ehare (ADOSA oy 
a, a Ray trie 03 1 od 4 Sat DAD 1 1 19 19 1 - ’ wimicaetoo 2. >S 110 i i) ANSISArsS : a iey ll 
2 —_ & dea ma agcvecestecsdencs weet ag, 2s sopag Thay ae svi DHS = 
me . oO re nial bar e . an *st ° ’ ‘ ~ 

= 2 Fob as MeOrMowoo : BS 9S 69S 09 15 I NH OG 1919 O ©1010 a ‘ rT] 2S ONO aps 3 

S§ | g8e58 | So 7 Sine | fee Sid seucceecessnescae — i issisia cit $82 & 

S : S patter Rig ate 28 1OHOWO p 5 Siaseaen ce PEER pee > A AD AD UCD eee oo'~ 
ee ones - Siege eg, ss: joy Hameuty st ia asen Ge ee tna ee ce cegeer cect aan Bey 1 
ns 3935 12 : pee ‘rt eee eg SSRISSRS tot ott ncatotnt antat Ip & 
Has eel Eien — ee Rey ade {ASSOC diaeunsengeaases OM. oa 

sa | 4 Se eee = Hee oo a oe ee sddsga he 

4 ' co : ng eas wi 2 a) Ldg @age = eRe vie om sen “S = IHD ODIO —- E ‘E 3 nN 

in < Ss" AARRRARAKRS ee etacighSacedel ghairt chan hat wl cee . by ae et a Seg. 

nN oco ; a Siietadine eis 1m CO E oes ome ee nN 
= Se wa.saee cobs ce SE Se ee AS RSH MS GO Dee tue Lae 329 

eS g —— Sjpay spacing ytd eee) Sp glagesdaredsieeae 3H Hi a 

r g RISK AE TES BEBSSSESSSRRER Wcignasisdddgnddadsdn a 3o cer 

a Piiiiipiind Seg a ae RRERRLKKLKAR dered ie 434 35 

a q Shape Seat aa ESE S Sa wy, CO 90 OS Se Sod wx gaa 2 5 

< Se de. Gre ite Se OR aC SS en TH amo - 

al senha dene bbw Piiiiiiisiiin: : $9 53 68 & 58 5B 06 03 & 3a 

ay ee ee pee ‘ Arete BNL my Oh 08 SPER Bik par a aa ps ses RY 1 One . = ——- SOO SAS gasdy | 
B18 ECO TS OL ede oR ag a a arparesiccs < ete +e Pee er etn, C3, Va ‘ ae rE 3 = 
xX£S2z53 o Le we 9 . ; oi . ‘ : ert. fa - i p ogee . om oe oe ee : iciunnilaia ud oe ee : ere 5x Re N 
REPEFESEOREFER ERROR EE ot ortestirereneerteatered PEbbbpbiiiin: 1 eee gee Sheed Y 
RRS8eoq iS set BN ae ae re Paes dia Sati rt ae rep rz i gt azo es | 
— Sdtesssse Batic rere a ley ote : here Phat Ge etait et \ | Zax 
. bol for) vee E utens i . omm O 8 Le Da. » cs ees a ae | i V gis 
= Sangean ay ee . nee o bet an wate Che dete ee he 8 fyi ¢ + 8 \ ie ° iey > 
; REFEREE ARPT BRAS FOE" B OF PiGiPibiiiiiiii Be oS) 

Coe ee op gis 
sRORMERECE SR TROT PRESET be fi ator 

euadsisavte ; 98 ee TO ern 4 

éseSddddeses Ago sa 

vay. res LABS aog° 2 


10 BULLETIN 1112, U. S. DEPARTMENT OF AGRICULTURE. 


TaBLE 7.—Basic data for 107 felled trees showing the effect of mistletoe on the growth and : 
seed production of western yellow pine—Continued. ea 


4 


ns; Diame- : De- Aver- Aver- 
Diam- Height Volume 
ter | Total | growth | Potal 


eter growth| 8f& | Crown length lonate 
oO 


growth |, ~ ol- cr 
breast fordast height.| for last for last of leaf r91R. 


Seed 
Tree number.|} Age. 


ume. infec- 
5 years. 5 years: 5 years.! tion, leaves. | tufts. 
Years.| Inch. | Inch. | Feet. | Feet. |Cu.ft.| Cu. ft. Inch. | Inch. 
Zee t ee 93 6.8 0.1 | 22.5 1.0] 2.30 1.80 | xxx C 3.1 3.3} O 
OU re 8 EBS oe 93 8.9 -4| 36.0 1.0} 5.65 1.01 x x 4.5 6.5} O 
Die Fae hae 94 12.0 1.5] 40.5 1.0 | 15.18 4.40 oOo KX Weel Senet Oo 
A2 5K OS Bhar 94| 14.8 -2) 41.5 -5 | 20. 03 Gd |) xxx x 4.5 5.6] O 
y (i Ber es AE BS. 94 9. 8 -7| 39.0 1.0] 7.80 HP’ hke. 0.0.4 Cc 3.1 4.6] O 
he EAT SOS 95 4.0 tt | 921.0 1.0 . 84 -16 | xxx Bo Pest, bier O 
BOA ayes. 95| 14.4 -3| 42.5 1.0 | 16.37 42 | xxx C 4.0 5.0} O 
SE S2os bees 97 9.0 5} 43.0 1.0] 7.06 - 85 x C. 4.6 5.3} O 
yO eRe aR 98 18.1 1.5 | 64.5 6.0 | 47.49 6. 48 x x 6.3 | 11.3 O 
AER Sie os ee 100 8.3 -2] 30-0 -5 | 4.23 28 > XK D 4.5 3.6] O| 
Sa AS. Se eet 100 | 146 -2) 49.5 1.0 | 20.05 1.08 | xxx C 5.2 5.5 | -O 
eS ae Ae Sea 102 | 20.6 1.0 | 64.5 3.0 | 52. 44 6. 81 (0) C 4.7 6.3} O 
IZA. Ree 104 12.4 oO Pale 1.8 | 13.13 a 17. (0) x 5.3 6.1 Oo 
Os Be 104 | 21.6 do A Seo 3.5 | 63. 47 5. 73 Oo Cc 4.8 5.7] L 
Ob Ce YB aes 105 | 20.4 -6| 60.5 15) '62; 11 4. 30 x C 5.2 240 
AO Ss aka 106 9. 4 8 53.0 3.0] 8.62 . 92 xx C 5.3 6.6 O 
3) Bat ae Phe eee 2 jor BG 1.24 62.0 3.5 | 18. 82 5. 59 (0) Cc 5.0] 10.6] O 
96>. ot See 114} 188 «6-705 1.0 | 43. 68 1.64] xx Cc 4.3 6.8} O 
OAL eRe: 2 117 | 20.4 1.0 | 78.0 3.0 | 69. 85 5. 05 (0) C 6.1). 62)2L 
ga oS Eee OS SN 120 19. 4 .4 | 67.0 1.0 | 42, 59 1.32 Bo. Cc 4.3 3.6 oO 
tf ee a tw 120.| 22.4 LZ evorb 2.5 | 83.56 | 11.32 (9) C 5.4 6.8} L 
AL (el Gee, 121 11.9 -8| 58.0 1.0 | 16.10 1.09 | xxx Cc 5.3 6.6] O 
Qi Rise SF Rat se 123 17.6 | 46.5 .5 | 21. 86 {58> REX x 4.6 5.1 O 
CS Nines Om ee 124 20. 2 7 | 268.5 1.0 | 67.68 9. 40 (9) x 6.0 9.0 O 
OD AR Fos as 125 Let -4| 68.0 1.0 | 43. 33 Se (5. |> FX C §.1 5.0} O 
Sodas - 5-8. oe 126 20.3 1 <3 55. 5 -3 | 42.03 1.49 | xxx x 4.0 2.5 oO 
SOE SoG Bee 130 | 23.4 2.3'|. 79.5 1.5 | 92. 78 8. 56 (0) D 5.0 83) M 
269205 Buss. 134 18. 2 -2| 45.0 -5 | 25. 23 «82)|\ aexx D 3.6 2.5 O 
1652 Pas 138 | 20.2 4) 59.5 -5 | 50.01 3. 74 x x 6.11 ALS} -O 
S645. Rese. 214 19. 2 1.231 (6755 1.5 | 44.90 4.27 (9) Cc 5.6 Wit L 
102 Ree. 214 | 23.0 1.4] 85.0 1.0 |108. 80 7.98 (0) Dy 2 5.5 5.3] M 
Beiter de tae «2 217.) 18,2 «5 | “5825 1.0 | 32.92 2362! |) Ex x 4.7 83) L 
1 ea 218 18. 2 -4| 78.5 -2 | 59.68 2265) | EXE Cc 2B. \sdeccss O 
1002 53: oes 218 |- 20.8 -5 iG D 1.5 | 71.92 2. 63 0) Gi. 3 5.3 5.2 O 
ROME ae. 2. 218 | 25.6 1.°3) | V S765 1.0 |133. 67 10.17 (0) x 4.8 5.8 L 
Sia. te wees ce 220 16.0 Bt 84.5 -3 | 54.91 4.15) |= max C 5.0 pes O 
ms 7 oe Ua ae SP 220 21.6 .8| 87.5 1.0 | 90. 26 7. 06 (0) D 5.8 7.3) M 
O45 ere 230 | 25.6 .4 76. 5 .3 |107. 47 2.88 | xxx x 624+ 8&8 O 
er ee a 233 17.6 2 72.0 -5 | 65.10 5.68 | xxx C 4.5 5.6 O 


Figure 1 shows the graphic growth analysis diagram for tree No. 4, 
a typical healthy western yellow pine, while Figure 2 shows the same 
kind of a diagram for tree No. 27, which was heavily infected with 
mistletoe. Both trees grew within a short distance of each other on 
‘the same site; they were of practically the same age and both belonged 
to the isolated crown class and the 101 to 140 year age class; there- 
fore these factors can not be held accountable for the material falling — 
off in the increment of the heavily infected tree.. The very marked 
decrease in the rate of growth during the last 30 years, evidently due 
to the parasitism of the mistletoe, is very clearly shown by the close- 
ness of the last seven quinquennial lines near the outside of the con 
in Figure 2, which represents the growth of tree No. 27. gee 

A set of curves was drawn for each tree showing the relation of 
age to diameter breast high, total height, and volume. This curving 
eliminated the irregularities and irrelevant abnormalities occurring — 
in each tree. The data for the individual trees were then averaged — 
by a series of harmonized curves for each infection and 40-year age — 


7 


THE WESTERN YELLOW PINE MISTLETOE. 


(a 
) 


ht in Feet 
$; & 


Sse 
= 


‘a 
) 


uy 
2 


ie 


109 ] 
Sor es hb 


Fig. 1.—Graphic representation of the growth analysis of felled tree No. 4, a sound 
_ healthy western yellow pine. (Height greatly reduced in porportion to diameter.) 


RE. 


J 


f felled tree No. 27, a western 


ysis 0 


U. S. DEPARTMENT OF AGRICULTU 


a 


N iY) AY) 
40ay Ul 446/ay 


yellow pine heavily infected with mistletoe. (Height greatly reduced in proportion 


“~ 

NX 

re 

rm 

re 

2 a 
iJ 

A : = 
o 

‘o 9 

e Be 3 eee Pee as Moe eR eR ei Ry 8 ogg ah SY LS hag” en) ae eee =| 

8 3 

FQ g 


Fia. 2.—Graphic representation of the growth anal 


12 


THE WESTERN YELLOW PINE MISTLETOE. 13 


ee 


nade 


Sb diten* 


— 


Pe SS Paes 


. 
‘ 


5 


3) 


Age in Years 


PR EE 


Fic. 3.—Volume-age curves showing the effect of the four degrees of mistletoe infection on the 21-60and 
é 61-100 year age classes. 


8 


§_& 


3 
e 
o 
~ 
Ss 
9 
s 
+1) 
g 
3 
> 


& 


8 


80 90 100 j10 120 139 140 160 160 470 
Age in, Years 


Fic. 4.—V olume-age curves showing the effect of the different degrees of mistletoe infection on the 101-140 
and the 201-240 year age classes. 


14 BULLETIN 1112, U. S. DEPARTMENT OF AGRICULTURE. 


class. Forty-year age classes were used instead of the usual 20-year 
age classes, because they provided a greater number of trees as the 
basis for each age and infection class. 

The harmonized volume-age curves for the 21 to 60 and the 61 to 
100 year age classes are shown in Figure 3, which indicates that the 
mistletoe infection was sufficiently severe to retard the rate of growth 
of the more heavily infected trees of these two age classes by approx- 
imately 20 years. Figure 4 shows a similar retardation of the incre- 
ment for the 101 to 140 and the 201 to 240 year age classes, except 
that the rate of growth of the more heavily infected trees of these age 
classes has been on the decline for the past 70 to 80 years. The 
curves in both figures show conclusively that the current increment is — 
directly dependent upon the degree of mistletoe infection. Gener-— 
ally speaking, the degree of mistletoe infection increases with the 
_ length of time which a tree has been infected. 

A further comparison of the average diameter growth or accretion — 
of the felled western yellow pine trees for the 25-year period from 
1890 to 1915, grouped by 40-year age classes and degree of mistletoe — 
infection, is shown in Table 8. A similar comparison of the average 
height growth or accretion of the same trees is given in Table 9. 
Table 10 shows a comparison of the average volume growth or incre- — 
ment of the same trees for the same period, similarly grouped by age 7 
and infection classes. The 21 to 60, 61 to 100, and the 101 to 140 year © 
age classes in Tables 8, 9, and 10 are composed entirely of black jacks, 
while yellow pines constitute the 201 to 240 year age class. 


TABLE 8.—Comparison of the average diameter growth or accretion of 102 felled western — 
yellow pine trees, for a 25-year period, grouped by age classes and degree of pratltogs 
infection. 


Diam- Ac- Ac- Ac- Ac- Ac- 
De eter cre- cre- cre- cre- cre- 
reo | breast | tion, | Diam-| tion, | Diam-| tion, | Diam-| tion, | Diam-| tion, 
8 f high. 1890- | eter |1895-| eter | 1900-| eter | 1905-| eter | 1910- 
Ageclass. ee 1895, | breast} 1900, |breast| 1905, | breast} 1910, | breast} 1915, |Basis. 
feo. | |_| Peri- | high, | peri- | high, | peri- | high, | peri- | high, | peri- 
tion odie | 1900. | odie | 1905. | odic | 1910. | odic | 1915. | odic 
100. | 1890 | 1895 | an- an- an- an- an- 
o nual nual nual. nual nual 
Years ER eins In. In. In. In In. In. In. In. In. | Trees 
21-to 60. 522 Ce) 0.8] 1.0] 0.04 P64 Os 2:3)" Oks 3.7} 0.28 5.0] 0.26 11 
x Ay? -6 .08 1.4 .16 Dit <2 3.5 . 20 4,4 18 6 
2.4 <li 4 . 06 .8 .08 s Ree .10 1.8 .10 2.1 06 t 
5. @. a (ee vie . 06 .6 . 06 7 -02 .9 . 04 11 04 & 
61to0100....) o eH eh . 20 9.3 322;| 1054 By ppl hema 59 -22/] 13.0] 30 12 
x 6.6") “7.0 14 8.0 .14 8.7 314 2 S238 12 9.9 wae 
». 0.4 6.0} 6.8 .16 io 14 8.1 rtZ 8.6 .10 9.0 08 
SEX 6.88. cob 14 8.2 14 8.7 7k 9.2 .10 9.4 . 04 17 
101 to 140...' o 15.0 | 15.7 SLE is DBOL5 5 6 ETS .20| 18.6 .22} 19.8 . 24 6 
x 44, 5-).b5s1 a a Fae the 3677 -16 | 17.5 16 f Teso en 6 
xx |14.8|15.2 .08 | 15.7 -10-| 16.1 -0O8 | 16.5 .08 | 16.9]. .08 6 
xxx 15s 2 156 .08 | 15.9 - 06 16.3 .08 | 16.7 .08 | 17.0 - 06 
201 to 240...| Oo 17.8 | 18.5 «4 teb9d oe Ws 1 Me Bgl 1 5 ‘Saag Ua 20° |, aenk .20 5 
Sx | 6 20 . 06 17.4 eh = IN lao W gen” -06 | 17.9 -04] 18.2 . 06 


—S oe TY ee ee ee ee eee See ee eee ee ee 
: } t 


THE WESTERN YELLOW PINE MISTLETOE. 15 


TABLE 9.—Comparison of the average height growth or accretion of 102 felled western 
yellow pine trees, for a 25-year period, grouped by age classes and degree of mistletoe 
_ infection. 


Accre- Accre- Accre- Accre- Accre- 
De- Total tion tion tion tion tion 
A gree height. 1890- | Total | 1895- | Total | 1900- | Total | 1905- | Total | 1910- : 

‘l ge of 1895, |height,| 1900, {height,] 1905, jheight,| 1910, |height,| 1915, |Basis. 

infec- peri- | 1900. | peri- | 1905. | peri- | 1910. | peri- | 1915. | peri- 

tion odic odic odic odic odic 

1890 | 1895 jannual annual annual annual annual 

Years. Feet.| Feet.| Feet. | Feet. | Feet. | Feet. | Feet. | Feet. | Feet. | Feet. | Feet. | Trees. 
21 to 60...-. r¢) 3.2 5.4 0. 44 8.0 0. 52 153 0. 66 14.9 aye) 18.6 0. 74 link 
x 2.6 a | . 50 8.3 . 64 12.2 . 78 15.3 - 62 18.2 - 58 6 
2.&.¢ LS ete fo 2o2 4.6 . 28 6.1 . 30 7.4 . 26 8.6 - 24 fi 
/ > do, 2 (NR RAS Jo Mie A $24 3.8 . 26 4.9 22 By? .16 6.3 59) 5 
61 t0 100....| 0 Bi. 4 31.5 7821035. 6 .82}] 39.5 AS» 4002 -74| 46.6 . 68 12 
x 29.6 | 32.2 -52)]..34.6 . 48 36. 8 .44| 38.8 - 40 40.8 - 40 7 
xx | 20.7.1 26.1 - 48 28. 3 -441 30.5 44 32) 1 302 30.0 - 24 9 
xxx | 23.4 | 28.4 -40 | 30.0 7-40 hats ey) 24) 32.2 -20} 33.0 .16 17 
101 t0 140...} o | 589) 61.5 soo") O4ee, .54) 66.9 54} 69.7 OD ete 56 6 
x 49.4 | 51.8 48 53. 5 . 34 55. 0 . 30 56. 4 - 28 5%. 5, 322 4 
Sx | 55.8 57.9 -42] 60.0 Tan G19 -38 | 63.5 ef ae 50) .30 4 
xxx | 46.4 | 47.8 - 28 49.0 . 24 50. 0 20 50. 6 .12 Sil? ah 4 
201 to 240...). o 7 Uys wa bel onpe G - 24 77.8 Ay. 78.9 ay.) 80. 0 22 81.2 124 5 
ER) | 7LI4 |. 72.0 sal G22 .10 73.0 .10 73.5 10 74. 0 .10 5 


Tas.E 10.—Comparison of the average volume growth or increment of 102 felled western 
yellow pine trees, for a 25-year period, grouped by age classes and degree of mistletoe 
infection. 


De- Increment, Total Tncrement, Total 


gree Total volume. 1890-1895. volume. 1895-1900, volume. 
Age class. REDS ae SS 1 ae ee oer eee Ck eee. aeRO mNs (es ae 
ee | 1800 1895. | Periodic annual. | 1900. | Periodic annual. | 1905 
Cubic Cubic Cubic Per Cubic Cubic Per Cubic 
Years. feet. feet. feet. cent. feet. fect. cent. feet. 
P21. 16... 602'5 22.3 (6) 0.36 0.54 0.036 Q@) 0.80 0.052 (1) 1.19 
x .02 .05 BOOG fase errs . 20 X13) essere -41 
xx 01 02 SOO Zahirers eel rahe .08 By 10 Ufo its Te A .14 
PRR eh ec roe SN ee SSIS chute le chute 04 SOUS" se Soa ae te -08 
61 to 100... ..... (s) 3.77 5.40 326 8.6 7.54 -428 7.9 10. 23 
x 4.90 5.91 . 202 4.1 7.10 . 238 4.0 8.49 
2.4 2.53 3.24 142 5.6 3.98 . 148 4.6 4,81 
ox 4.12 4.94 164 4.0 5.72 156 3.2 6.46 
10) to 140...... ce) 35.10 39.78 936 2.7 44,80 1.004 2.5 50. 26 
‘ x 25.95 30.15 840 3.2 34. 80 930 Sek 39. 20 
3.4 23,42 26.35 526 2.2 28. 62 454 | ef 30.75 
xxx 20.02 21.04 204 1.0 22.87 366 14 24.10 
202 to 240...... fe) 59. 06 63. 94 976 ea, 69.38 1.088 Laie 15. 72 
p. 0.0.4 52.16 54.36 440 8 56. 56 0 &S 58. 94 
# De- Increment, Total Increment, Total Increment, 
ft ri 1900-1905. volume. 1905-1910. volume. 1910-1915. B 
Age class. 5 eS A ESE: SRLS PS, SEU Se ae eee Pe mT) ae EP Sig: 
Mae Periodic annual. | 1910. | Periodicannual.| 1915. | Periodic annual. 
Cubic Per Cubic Cubic Per Cubic Cubic Per 
Years. feet. cent. feet. feet. cent. fect. feet. cent. |Trees. 
21 to 60.....22...| 0 0.078 (1) 1.81 0.124 Q) 2.67 0.172 () 11 
x 5 A ee ae . 86 OOO ose Se 1.25 Ufo’ er Sere 6 
xx AULA a eT le 24 POZO Ne ee FiC6 O26 COAL E Je ae 7 
2.2.9.4 US e ses ee -18 O20) peewee ok .29 OOF te ee 5 
61 TO 100 e250 - 538 7.1 13.52 658 6.4 17.28 752 5.6 12 
a < -278 3.9 9.89 280 3.3 11.49 320 3.2 vi 
xx - 166 4.2 5.65 168 3.5 6.52 174 3.1 9 
xxx . 148 2.6 t.42 132 2.0 7.70 116 1.6 17 
101 to 140........ (0) 1.092 2.4 56.48 1.244 215° 63.41 1.386 2.5 6 
x - 880 2.5 43.72 904 2:3 48.07 . 870 2.0 ‘4 
2.7 -426 1.5 32.70 390 1.3 34.60 . 380 1.2 4 
i x . 246 1.1 25.32 244 1.0 26.42 . 220 9 4 
201 to 240........ (0) 1, 268 1.8 82.46 1.348 1.8 90.12 1.532 1.9 5 
5.O. ©. 476 8 61.38 -488 8 64.00 - 524 -9 5 


1 The periodic annualincrement per cent was not computed for the 21 to 60-year age class because of the 
ey sma]linitial volumes and the proportionately great effect on the percentage of slight individual 
ions. 


-. showed marked vigor and was 4 feet tall, whereas the one infected — 


16 ‘BULLETIN 1112, U. S. DEPARTMENT OF AGRICULTURE. “a 


In the early stages of the study the trees were segregated by crown . 
classes. Since by far the greater part of the trees in the open park- 
like stands studied were in the isolated, dominant, and codominant — 
classes, the effects of crown class were found to be negligible in con-— 


trast to the marked effect of mistletoe in retarding the rate of growth. _ 


The retardation of growth due to the mistletoe was consistently — 
evident in each age-crown class in which sufficient trees were secured — 
to form a comparable basis. It was impossible to secure an equal 
number or équal proportion of each crown class in each age-infection 
class. As has been shown, it was found more necessary to segregate 
the felled trees by age-infection classes than by crown-infection 
classes. It was impracticable to segregate by crown classes all of 
the trees used in this study because of the extremely small number 
and in some cases entire lack of trees falling into each age-infection- 
crown class, had such a triple classification been used. The diameter, 
height, and volume growth during the 5-year period, 1910-1915, in 
the 21 to 60 year age class of the isolated trees included in Table 7, may 
be cited to show the injurious effect of —— on growth within a 
given age-crown class, as follows: 


‘{Breasthigh} Height Volume 
diameter owth owth 


Degree ofinfection. growth for br last or last Basis 
last 5 years.| 5 years. 5 years. 
Inches. Feet Cubic feet. | Trees 
Dee eee ee aes os 2 lide 0 ais Reig wie oe ee OR 1.3 3.3 2.04 3 
ME Bina wm nice bs haope s Me s,0 9 OPES ore cine ee 8 2.0 . 54 2 
Beak | oeuee - 22 Satin Bae ood oct ap aeos tees tee ee 6 1.2 25 3 
SS oper eiats oS SRR aes Bh MR Tegel Art ee 2 (1) a8 . 004 4 


1 The trees in this class were less than 4.5 feet in height. 


In Table 11 is shown increment data for two intensive sample 
plots aggregating 24 acres, located within the extensive plot on the — 
Tusayan National Forest mentioned below, the data being grouped 
according to degree of infection. An accelerated growth is noted ~ 
in the x infection class comparable to that noted in Table 1, the 
explanation of which is not evident from the data at hand, unless — 
it be an actual stimulation due to the presence of the mistletoe. — 
The decrease in the rate of growth in the heavily infected class is very . 
marked and is in accord with all of the other i secured in et 
study. 

Two seedlings, one healthy and the other henivily infected with | 
mistletoe, which were growing side by side on a good site, were ana- 
lyzed and both found to be 15 years old. The healthy seedling — 


with mistletoe was only 3 feet tall and showed evident stunting and — 
that death was imminent. 


PLATE 


Iture. 


cu 


ities S. Dept. of Aor 


Bu 


*9049]STUL 


Aq SSUTT[OMS JO UOT}VULIOJ oY} pue ouTd MoOTIOA U 


191SOM JO S8TM4 UO 90J0TISTUL Jo JUIUTCOTBASP ATIVO 9T[1 UT SO8VIS DATSSeOONS VIAL, 


“OOTXOJY MON 


*BUOZIIY ‘JSO10,J [BUOTJVN OUTUODIOD ‘sIvad JO JOQUINU &B IO} pvop \solot [eUOIeN oq eye *904JeT}STUL 

“euOZIIV ‘48010 \T uood sey ,,ouTd MOT[VA,, OY} O[TYM ATJWODE1 PoT[DyT ot ,,Syoul Aq posnvs UMOJO OY} JO JAR JOMOT OY} UT 

[euoeN OUTUOD0g ‘sOJeTJSTUL AQ poT[DT YoRvlq,, of ‘“sojoystur AQ pol[ky punoisyoeq oy} ut ,,ouid : SULOOIG ,SOYD}IM PUB soyoURIG poyUNys ZUT 
AT{Udde1 901} UTA MOT[OA U.I09SOM YW—e “DT MOT[A,, B PUB PUNOISoI0J oY} UI ,,syowl Yovyq,, OoMP—Z “DIT -MOYs 001} ouId MOT[OA Ulo}soM W—'T ‘OL 


PLATE III. 


Bul. 1112, U. S. Dept. of Agriculture. 


THE WESTERN YELLOW PINE MISTLETOE. tT 


The data presented in the preceding pages show that, although 
minor fluctuations dre exhibited, the rate of growth of the host 
decreases with the amount of mistletoe infection; or, in other words, 
is dependent on the degree of parasitism. Possible exceptions may 
be cases of very light infection which appear to act as stimulants for 
the host tree. These results are really to be expected when the 
effects of mistletoe parasitism are fully understood. 


TaBLE 11.—The effect of mistletoe infection on the rate of growth of western yellow pine 
on two intensive sample plots aggregating 24 acres on the Tusayan National Forest. 


® Basis 
EMG de Seba eee Total aces 
. . ameter annua. annu: of trees 
Degree of infection. growth, | increment, | increment, ae ets 4 inches 
1914-1919, | 1914-1919. | 1914-1919.1 ? *| and over 
+e). 
Inches. Cubic feet. | Percent. | Cubic feet. 
Se 0.70 4, 56 2.54} 1,636.2 359 
Re ate erate Fae a hood Soin baie Seg - ake. ote - 88 5. 65 2.79 553. 9 98 
oa Oe Ry) SNES ee ee - 49 2. 23 1. 83 254. 5 114 


1 On cubic-foot, basis. 
Note.—Since there were only 13 trees classed as moderately infected, they were omitted because of 


the small basis. 
EFFECT ON LIMBS, 

The first visible effect of the infection of a limb by mistletoe is the 
formation of a fusiform swelling (Pl. II) about the center of infection 
similar to those occasionally found on stems. This hypertrophy is 
the first stage of a later abnormal growth of branches from the en- 
larged portion, which results in the formation of witches’ brooms. 
(Pl. III, Fig. 1.) When the stimulus of the parasite has once become 
manifest through the formation of a broom, the tendency toward 
abnormal branching continues, although the aerial parts of the 
mistletoe have may died. 

The comparative diameter growth or accretion of 54 limbs on 18 
standing black jacks is averaged by infection classes in Table 12. 
Measurements were taken at 6 inches from the bole of the tree and 
at 6-inch intervals beyond this point. The measurements taken at 
6 to 18 inches from the bole of the tree were averaged and are pre- 
sented in the table to facilitate a clearer and more comprehensive in- 
terpretation of the significant data. Limb measurements were also 
taken on the felled trees to check the comparative growth of the 
healthy and mistletoe-infected limbs of the standing trees. From 
these data, which are summarized in Table 13, it is apparent that the 
limbs had been infected at least 25 years prior to the time at which 
they were analyzed. The data presented in both tables show that, 
for the limbs examined, the rate of growth in diameter of limbs 
infected with mistletoe is greater than that of uninfected limbs. Itis 

3600°—22—Bull. 11123 


18 BULLETIN 1112, U. S. DEPARTMENT OF AGRICULTURE. 


very probable that the increased diameter growth continues to a 
certain point, beyond which there is a pronounced decrease in the 
rate of growth, until the limb eventually dies. This increased diam- 
eter growth is probably caused by the formation of an excessive 
amount of pathological parenchyma tissue, as a result of the irritation 
of the cambium by the parasite. The softer parenchyma adjacent 
to the center of infection renders the infected wood somewhat weaker 
than the more highly-lignified tissues of normal, uninfected wood. 
The presence of the mistletoe in the limb produces a stimulated 
growth of the host near the center of infection. 


TABLE 12.—Comparison of the average diameter growth or accretion of 54 limbs on 18 


ers black jacks, for a 5-year period, grouped according to degree of mistletoe in- 
ection. 


Average diameter.! Accretion, 1910-1915. 


Degree of infection. 


Periodic 
1910 1915 Periodic. annual. 
Inches. Inches. Inch. Inch. Limbs. 
Osa coe oe et ents one Se ee Mee 3. 84 3.98 0.14 0. 028 20 
D a tied anda A Mag ty area be RAY silent, ional 3.90 4.06 -16 - 082 6 
b.2, CORE A AN eae eg et PCR cee TEP Me Mel gee le 4.35 4.62 74 . 054 7 
D2: ©, men ap ep Wa BA Rt Ie a 4.08 4.46 -38 .076 21 


1 Average of two sets of measurements taken at 6 and 18 inches from the bole of the tree. 


: 
TABLE 13.—Comparison of the average diameter growth or accretion of 8 limbs on 4 felled 


western yellow pine trees, for a 25-year period, grouped according to degree of mistletoe 
infection. 


Accre-| Aver- | Accre-| Aver- | Accre-| Aver- | Accre-| Aver- | Accre- 

Average | tion, | age | tion, | age | tion, | age | tion, | age | tion, 
diameter.1 | 1890- | diam-| 1895- | diam-| 1900— | diam-| 1905- | diam-| 1910- 
: 1895. | eter.1 | 1900. | eter.1 | 1905. | eter.1 | 1910. | eter.1 | 1915. 


Degree of : Fixe a eee ee 
infection. Basis 
ae eon Pen: Pa bat 
~ | odic odic odic odic c 
1890 | 1895 | So | 1900.) Fe), 005 | Se 10 ee eee 
nual nual nual. nual nual 
In. | In. | In. | In. | In. | Ine | In. | dn. |dn. | Ino (ne [hime 
ONte st dacee cee wees 1.68 | 1.84 | 0.032 2.01 | 0.034 2.21 | 0.040 2.34 | 0.026 2. 46 ~4 
DO. GR Ee pe 3.06 | 3.32 . 052 3.68 .072 4. 04 . 072 4.34 060 4.56 x 4 


1 Average of two sets of measurements taken at 6 and 18 inches from the bole of the tree. 


Eccentricities, especially hyponastic growth, are considerably more 
pronounced in limbs heavily infected with mistletoe than in healthy 
limbs. The formation of a large witches’ broom produces an abnor- 
mally heavy load which must be borne by that portion of the limb 
nearest to the bole of the tree. This abnormal load produces stresses 
sufficient to stimulate the formation of wood on the under side of the 
limbs through the deposition of food materials, which enables the 
wood to withstand the compression below. The tension above is over- 


| 
THE WESTERN YELLOW PINE MISTLETOE. 19 


come by the development of a special tissue on the upper side of the 
limb. 

The increased size of the limbs infected with mistletoe renders 
limbing and brush disposal in logging operations more difficult and 
consequently more expensive. The excessive secretion of resin which 
occurs in mistletoe-infected limbs has somewhat the same effect on 
brush disposal. 


HYPERTROPHY AND RESIN FLOW. 


Although mistletoe infection causes swellings on both branches and 
trunks, the stem swellings frequently become less noticeable as the 
tree grows. In many cases there are no pronounced swellings on the 
larger boles even when very old mistletoe infections are present, about 
the only means of detecting the infection being the presence of the 
mistletoe or the unusual roughness of the bark. (Pl. IV, Fig. 1.) 
When, however, infection occurs during the early life of the tree, 
it frequently results in the formation of a burl which may attain 
very conspicuous proportions. The fusiform swellings on both the 
stems and limbs resulting from mistletoe infections are centers where 
abnormal amounts of food materials are stored, which condition is 
evidently stimulated by the decided pathogenic tendencies of the 
mistletoe. The cortex is frequently gnawed from the lesions by 
rodents, especially porcupines and squirrels, attracted by the soft 
spongy nature and the greater thickness of the inner bark of mistletoe- 
infected branches and stems. This fact establishes a casual relation- 
ship between mistletoe infection and rodent injury. 

As previously stated, there is more or less hypertrophy at the point 
of mistletoe infection on both limbs and stems. This hypertrophy 
is frequently accompanied by a copious flow of resin, which appears 
as small drops, usually on the lower side of limbs, which are heavily 
infected with mistletoe. A cross section through such a limb shows 
large areas of the sapwood thoroughly infiltrated with resin. The 
process of infiltration contintes on many of the limbs until the fibro- 
vascular system is thoroughly clogged with resin; the limb is girdled 
as far as receiving any food supply is concerned, and is finally killed. 
This process is usually very gradual, but none the less sure. 

The resin flow from such mistletoe-infected limbs is not caused by 
insect punctures. A careful examination of the resin-infiltrated areas 
fails to show any signs of such injury. On many of the trees which 
are heavily infected with mistletoe, resin cankers (Pl. IV, Fig. 2) of 
varying sizes are found on the bole. These cankers are often directly 
associated with local mistletoe infection. The resin flows on the bole 
are usually indicative of the decline of the tree; in fact, trees with 
marked resin-flow cankers usually die in a relatively short time. 


20 BULLETIN 1112, U. S. DEPARTMENT OF AGRICULTURE. 


EFFECT ON THE FOLIAGE. 


Tables 14, 15, and 16 show the effects of the mistletoe on the foliage 
of the western yellow pine. The data included in Table 16 were 
obtained as follows: | 

Each tree crown was divided into three divisions—bottom, middle, 
and top—including in each division about one-third of the total leaf 
surface. One hundred tufts from each section were selected at ran- 
dom and measured; the mean length of these tufts was taken as the 
average length per tuft for that section. Then 10 tufts of this 
average length were taken from each of the three sections into which 
the crown had been divided. These tufts, 30 in all for each tree, were 
cut off and taken to the laboratory, where the number of leaves per 
tuft, the length, and the width of each leaf were determined. The 
total number of tufts in the bottom, middle, and, top thirds was 
determined by actual count. The number of tufts thus obtained was 
multiplied by the average number of leaves found in the 10 tufts 
from each section. This gave the average number of leaves in each 
section. ‘The sum of the leaves in the three sections gave the average 
number of leaves in any given tree crown. 


TABLE 14.—Comvarison of the length of leaves of 103 western yellow pine trees, classified 
according to degree of mistletoe infection. 


In lower portion | In central portion | In upper portion Mean for entire 


of crown. of crown. of crown, crown. 
tere ot Basis 
tnfection-| Mean | Mean | 4 ver. | Mean | Mean | 4 ver. | Mean | Mean | 4 yop, | Mean | Mean | 4 vor. 
mini- | Maxi-| “206. | mini- | maxi-| “276. | mini- | maxi-|“)02) | mini- | maxi-| “376 
mum.}mum.| 2®& |mum.|mum.} 98° |mum.|mum.| 28° |mum.|mum. ; 


In. In. In In In. In. In. In. In. In. In. In. | Trees. 
(0 Vegeta Pigameas 8 3.3 6.2 4.9 3. 8 6.3 5D 4.2 6.9 5.8 3.8 6.5 5.4 : 
Keteusce 23 Dao 4.0 2/5 5.9 4.5 a. 2 6.2 5.0 2.7 5.8 4.5 15 
5. ©. < 4x eit: 5.3 3.8 2.0 5.4 4.1 2.9 5.7 4.6 2.15 BaD 4,2 18 
XW. ci. Oeil 51 3.6 2.4 5.1 4.0 2.7 1 4.0 2.4 Be | 3.9 32 


TABLE 15.—Comparison of the length of leaf tufts of 97 western yellow pine trees, classified 
according to degree of mistletoe infection. 


| 
* In lower portion | In central portion | In upper portion Mean for entire 


of crown. of crown. of crown. crown, 
Degree of oo Te A 
infection.) Wean | Mean ‘Aver. | Mean | Mean | 4 \o,. | Mean | Mean | 4 vor. | Mean | Mean | 4 vor. tem 
mini- | Maxi- age mini- | maxi- age mini- | maxi- age mini- | maxi- age 
mum.|mum * |mum.|mum * |}mum.]mum. * }mum,} mum. ; 
In. In. In. In. In. In. In. In. In In. In. In. | Trees. 
OF te hese 3.441 745 6.7 4) ASD 10. 0 6.8 |.7:22% Tai ee 5.21 16.60]; 0a2 av 
mth a og ie Bet) 10.1 6.5 4.0 12.0 8.0 Dae 16.8 10.3 4,2 13. 0 8.3 15 
©. aa 2. 4 8.2 4.9 2.3 9.1 5.2 he ee P| tad AM 9.4 5.8 15 
D&O 23 8.1 4.5 2.6 8.6 570 2.4 8.5 4.8 2.4 8.4 4.8 30 


PLATE IV. 


Bul. 1112, U. S. Dept. of Agriculture. 


‘ouTd MOT[OA U109S9M UO OTST 
eoJopISTUL PTO UB UT SsuIdOfeAsp I 


eyueod UISOl VW 


—-7° 


9) Ay | 


‘ourd MOT[OA T904S8A\ TO 
UOTSI] 9OJOTJSTUL V JO DOUVAPR JO SSULI O1IJUVDUOQ—"T “HTT 


—=_ 


PLATE: Vi 


Bul. 1112, U. S. Dept. of Agriculture. 


‘OZIS [VINJLU YIYSI0-oUQ ‘porINds svM J OINSTY UI UMOYS YouvIG oY} 
TUM uwtoy dnois oures oy} Url 001} AYYTVoYy B UO pedofeaop SopoUlezUT J9sU0T 
puUe soAvoy JoSIvJ oy} SULMOYs OUI MOT[OA UJO}SOM Jo YouRIq [[VUIs VY—'Z “Ol 


‘OZIS [VINJLU Y}XIS-OUG ‘Uses oq ABU SUOTIOIJ 
UT [COT 9914} OTA JO ‘90JO]JSTUL OY} 07 ONP SopoUIOjJUT 10JIOYS PUB SOABOT 
JoT[VUIS PUB JOM} SUTMOYS eurd MOT[PA Udo}SaM JO YOuBIg ][VUIS W—'T “DIq 


THE WESTERN YELLOW PINE MISTLETOE. o1 


~TaBLe 16.—The effects of mistletoe on the photosynthetic surface of western yellow pine. 


gor ; Crown. 
Degree Teas Total Total Crown 
Tree number. pre sais Pi height. | volume. class. 
bark. 
Years. | Inches. Feet. | Cubic feet 
She XXX 80 7.5 20. 0 2. 50 x 
OA Pe aSiwicie we oon C4) , 79 14.5 42.0 19. 00 x 
DCSE SE Sables asin «<0 xxx 83 8.1 26. 0 8.55 Cc 
EMP iese eet are <yaicisie < «0 (0) 83 15.2 49.0 22. 50 C 
| Gea efile ee Fy a (8) 37 Ye | 21.0 2.40 D 
“! Length of leaf tufts. 
Lower portion of crown. Center of crown. Upper portion of crown. mentee te 
Tree 
num- 
ber. | Mini-[Maxi-|Aver-NU™/| mini-|Maxi-| Aver-[NU™-| Mini-|Maxi- Aver-NU™| Mini-|Maxi-| Aver- 


mum.|mum.| age. |} 7,, |mum.jmum.| age. | +57, |mum.|mum.| age. |. |mum.|mum.| age. 


In, | In. | In, In. 6?) fae FIM In. | In. | In In. | In. |} In. 
ee 0.5 s 3.2 81} 1.0) 80}; 3.8] 3829] 1.0]/12.0] 5.7] 234] 0.8] 9.0 4,2 
104..... -0)11.3] 5.3 2,161 | 2.0/13.0)] 5.4 |2,390} 2.0) 18.0] 8.0 1,151] 1.6] 14.1 6.2 
. -3/11.0] 3.7] 242 5|}12.0} 4.0} 183 6.1°13..0 }) 5.0). 176 -4 112.0 4.2 
TOG; 3).r-/. 1.0)11.0} 4.0 |1,522] 1.5/)17.0| 6.7 |1,228| 2.0] 26.0) 7.7) 445) 1.5]18.0 6.1 
107.....| 1.51)12.5| 6.8] 379) 2.5/180|] 88] 321} 2.5) 28.0) 10.0| 313] 2.1] 19.5 8.5 
Length of leaves. 
Total 
number Lower portion of crown. Center of crown. 
Tree No. of tufts 
in entire 


crown, Mean | Mean | Mean Wraahibie Mean | Mean | Mean Aumiber 
ofleaves.| Mini- | Maxi- | aver- | orieaves 
mum.|mum.| age. mum.|mum.| age. ? 


ee eS eS ee, ee 


In... In. In. In. In. In. 
1G ee 1.6 3.3 2.6 13, 122 ed, 3.5 2.6 62, 181 
tees TIS IS 3. 5, 702 9 4.9 3.5] 518,640 2.8 5a. 8.7 803. 040 
ESE ae Se 601 2.0 4.1 8.2] 109,142 PH 33 4,2 |-~3. 1 67, 161 
OO eee ss os 3, 195 4.1 5.8 4.9 | 365,280 4,4 6.7 Ded, 289, 808 
1 di ie athe el agate ea 1,013 3.3 5.2 4,5] 94,371 4,1 5.7 5.1 172, 972 
Length of leaves. 
Upper portion of crown. Mean for entire crown. 
Tree No. 
Mean Mean | Mean Mean 
: 5 Mean | Number of Roar - Mean 
mini- maxi- mini- maxi 
mum. mum, | 2Verage. leaves. mum mum average. 
In. In. In. In In. In. 
RTA, & Sie a 1.8 4.5 3.2 84, af Sed 2.8 
A Rect s wise & ice onee 2.8 5.1 4,1 470, 759 PH | 5.0 ay 
SNe Bees arias one dvs Sak 5.0 4.3 85, 712 2.4 4.4 BA) 
4 tes OS a cioiats bie, ajers'a:e 4,8 6.8 5.9 182, 005 4.4 6.4 5.5 
“ 25) Be aE oe ‘ 5,2 6.4 5.9 152, 431 4.8 5.7 wk 


29 BULLETIN 1112, U. S. DEPARTMENT OF AGRICULTURE. 


‘Taste 16.—The effects of mistletoe on the photosynthetic surface of western yellow | | 
pine—Continued. 


Leaf surface. 
Totalnum- 
Meee Wa ber of leaves : Ratio ofleaf] Ratio of 
: in entire Lower Central Upper Entire surfaces. | volumes.} 
crown. portion of | portion of | portion of crown. 
crown. crown. crown 5 
Square Square Square Square 
inches. inches. inches. inches. 
a Ui ames ares ti Sy 159, 543 4,094.1 19, 400. 4 32, 348.2 55, 842.7 1.0 1.0 
L0G e Sah oe 1,792,439 | 217,828.8 | 356,549.8 | 231,613.4 | 805, 992.0 14.4 7.6 
LOR. Sess See 262, 015 40, 910.5 24, 983.9 44, 427.4 | 110,321.8 2.0 1.4 
TOG es ee es 837,093 | 218, 438. 4 198, 228.7 | 128,939.5 | 545, 606.6 ; 9 ni 


809s, Ben 419,774 | 50,960.3 | 105,868.9| 107,921.4| 264; 750.6 4 ; 


1 In these ratios Tree No. 103 is taken as unity. 


The average length and width of the leaves in the 10 tufts selected 
were used in determining the leaf surface for a given section of the 
crown, and this in turn for finding the total leaf surface of a given 
tree. Table 16 shows that not only does the mistletoe shorten the 
length of both leaf tufts and leaves, but it also materially decreases the 
number of leaf tufts per tree for heavily infected trees when compared 
with healthy trees of the same age and site conditions. (Pl. V.) 
When two trees of the same size, one healthy and the other heavily 
mistletoed, are compared—Trees No. 103 and No. 107, for instance— 
it is seen that it has taken the mistletoe-infected tree more than twice 
the number of years to reach the same size as the healthy tree. The 
average ratio of the leaf surface in square feet to the total volume in 
cubic feet for the healthy trees given in Table 16 is 409.7 compared 
with 185.5 for the heavily infected trees. 

Trees heavily infected with mistletoe not only have considerably 
shorter leaves and leaf tufts than healthy trees, but the leaves of 
mistletoe-infected trees are lighter in color than those of healthy 
trees, being a yellowish green as compared with the olive green on 
the healthy trees. Each heavy infection causes a localization and 
reduction of the photosynthetic or assimilatory leaf surface of the 
tree, which in turn results in a marked decrease in the rate of growth. 


EFFECT ON LONGEVITY OF HOST. 


A number of permanent sample plots were established on the Coco- 
nino and Tusayan National Forests by the Fort Valley Forest 
Experiment Station, in 1909, to determine the rate of growth and 
decadence, the rate of establishment of natural reproduction, and the ~ 
effect of various factors upen regeneration on cut-over areas. These 
plots were remeasured in 1914 and 1919. Some of the plots yielded 
valuable data on the amount of ee infection and the resulting : 
mortality on cut-over areas. 


” (HE WESTERN YELLOW PINE MISTLETOE. 23 


On an area of 456 acres on the Tusayan National Forest about 5 
miles from the Fort Valley Forest Experiment Station, 2,636 black 
jacks, or 34.9 per cent of the total number on the plot, and 225 
yellow pines, or 34.8 per cent of the total number, were infected with 
mistletoe in 1914. In 1919, 2,335 black jacks, or 28.8 per cent of the 
total number of trees 4 inches in diameter and over, were infected with 
mistletoe. In many instances the infection was not sufficient to 
render the tree unhealthy, but with the increase of infection many of 
the infected trees will pass through the various infection classes and 
eventually die. 

All of the trees which had died on the plots during the two 5-year 
periods were carefully examined and the cause of death noted. On 
the plot of 456 acres on the Tusayan National Forest 170 black jacks 
died from various causes during the first 5-year period, or 2.2 per 
cent of the total number of black jacks living on the plot in 1909, 


‘while 21 yellow pines died during the 5 years, which is 3.4 per cent 


of the total number of yellow pines living on the area. During the 
5-year period from 1914 to 1919, 127 black jacks,died from mistle- 
toe alone, or in conjunction with other agents such as insects, porcu- 
pines, etc. 

On a plot of 135 acres located on the Coconino National Forest 
about 14 miles from the Fort Valley Forest Experiment Station, 27 
black jacks died from various causes during the first 5 years, which 
is 1.1 per cent of the total number of black jacks living on the plot in 
1909; 26 yellow pines, or 1.8 per cent of the total number, died during 
the same period. 

A digest of that part of the detailed records pertaining to mistletoe 
as a cause of the death of western yellow pine during the 5-year 
period from 1909 to 1914 is given in Table 17. The 456-acre plot on 
the Tusayan National Forest is located on an area which has sus- 
tained heavy losses from mistletoe, while the 135-acre plot on the 
Coconino is located on an area with only occasional heavy infections. 
A study of Table 17 indicates the mortality of western yellow pine on 
these two areas and the extent to which mistletoe was a direct cause 
or a contributing factor. A study of Table 17 also indicates that of 
the 170 black jacks on the Tusayan plot which died during the 5- 
year period 26.4 per cent were killed directly by mistletoe, 42.3 per 
cent by mistletoe combined with other agents, and only 31.3 per cent 
died from other causes; while only 4.8 per cent of the yellow pines 


_were killed by mistletoe combined with bark beetles. On the 135- 


acre Coconino plot mistletoe infection alone resulted in the death 
(Plate III, Fig. 2) of 7.5 per cent of the total number of dead black- 
jacks and 7.9 per cent of the total number of dead yellow pines, while 
mistletoe was a contributing factor toward the death of an additional 
20.2 per cent of the yellow pines. During the 5 years 1.5 per cent 


/ 
24 BULLETIN 1112, U. S. DEPARTMENT OF AGRICULTURE. 


of the total number of black jacks on the Tusayan plot in 1909 were _ 
killed by mistletoe alone or in conjunction with other agents, mainly 
insects. While this figure itself is not high, it is alarming because 
the indications are that the death rate will increase from year to 
year, and although an effort was made to have all heavily infected 
trees removed when this area was marked for cutting, it is evident 
that mistletoe did not receive the attention which it deserved. 


TABLE 17.—Classification of dead trees on permanent sample plots of 456 acres on the 
Tusayan and 185 acres on the Coconino National Forest. 


Per cent of dead trees, 1909-1914 (based 
on total number of trees which re 
during 5-year period). 


456-acre plot, Tu- | 135-acre plot, Coco- 
sayan National nino Nationa 1 
Forest. Forest. 


Cause of death. 


Black | Yellow | Black | Yellow 
jack. pine. jack. pine. 


ee ee 


Mistletop. 22542 35.2 PARA Soe Seg SOE Ee Bee oe ie phe aps Re 

Mictiotae attrl TRGeCI eo ee oe ee eee 35. 0 sO i Reng ae Sh 20.2 

Mistletoe and Poreupine. 2 ee. SS ke ca, 2200 oe wee ee oe B.D ios o's = 5 bie gape sd a ert 

Mistletoe and suppression . . 2.1. - 22 anne en ne ool s we bolas = = ee eee eee 

Mistletoe, porcupine, and insects +. ot = ecnuy -n4-s cheap eeoeee oF |. wan acinn ahs mel crteele ee 

AU ote? CAUSES <5 tke oe nae eee cae: eee eee eee 31.3 95. 2 92.5 71.9 
01 ee ee i Se at Ea 5 goat PRO WMEON y etadas yp APB de! 100. 0 100.0 100.0} 100.0 


Weir * has noted the same direct relation between mistletoe infec- 
tion and insect infestation in the Northwest, especially with Dendroc- 
tonus valens. The origin of numerous insect infestations has been 
traced to stands of western yellow pine heavily infected with mis- 
tletoe. 

The main difference between mistletoe and insect injury is in the 
length of time required for the injury to become manifest. A 
sporadic insect infestation may develop rapidly and may kill a large 
number of trees in a relatively short time, and it may even continue 
to increase until it is overcome and reduced to normal proportions 
through some natural agency. Mistletoe, on the other hand, de- 
velops slowly but continuously and persistently. The bark beetles, 
when attracted by the resinuous exudations of the mistletoe-infected 
trees, may materially hasten the death of the host which has already 
been weakened by the parasitic mistletoe. Trees dead or dying from 
mistletoe infection have been found infected with species of secondary 
bark beetles and borers, such as Ips, Pityophthorus, Chrysobothris, 
and Melanophila. 

Three black-jack saplings under 4 inches in diameter breast high on 
one of the intensive mistletoe-study plots died during the five-year 


4 Weir, James R,, Mistletoe Injury to Conifers in the Northwest. U.S. Dept. Agri. Bulletin 360, 39 pp., 
1916, 


THE WESTERN YELLOW PINE MISTLETOE. 25 


period as a direct result of mistletoe infection. Five yellow pines 
on the same area were also killed by mistletoe during the same period. 
Many of the other trees on the sample plots, although not dead at the 
last examination, were small and stunted; they were making an 
almost inappreciable growth and were very unhealthy in appearance. 
Some of these, which are apparently unable to endure the parasitism 
of the mistletoe combined with a rather adverse climate, will un- 
doubtedly succumb before the remeasurement of the plots at the 
end of the next five-year period. Practically all of the trees which are 
heavily infected with mistletoe are ultimately doomed, since it is only 
a question of the length of time during which they can withstand the 
insidious action of the parasite. 


EFFECT OF MISTLETOE ON MERCHANTABILITY OF TIMBER. 


Although the mistletoe injury to the host results less in the depre- 
ciation of the lumber than in the impairment of the vital physiological 
functions of the tree, there is nevertheless an appreciable effect on 
the quality of the lumber. The accelerated growth of mistletoe- 
infected limbs, as shown in Tables 12 and 13, results in larger limbs 
which produce knots of a larger size in the lumber that is sawed from 
the boles of the mistletoe-infected trees. The number of knots is 
also increased by the greater number of secondary branches and 
twigs-in stem infections. ‘The increased size and number of the knots 


_ May, in many cases, be sufficient to lower materially the grade of the 


lumber. 

Mistletoe-infection produces a curly or abnormally grained wood 
and weaker lumber. Wood invaded by the thread-like ‘sinkers of 
the mistletoe is spongy, and is frequently discolored and pitchy, as a 
result of the resinous flow or bleeding of the trees. The presence of 
mistletoe burls renders a tree more susceptible to wind breakage; in 
addition, it may ruin a portion or all of a sawlog. A seedling or 
sapling whose stem is infected with mistletoe will seldom develop a 
bole large enough to yield any considerable quantity of lumber and 


very rarely, if at all, lumber of a high grade. It is therefore evident 


that, aside from the physiologically injurious effect of the mistletoe, 
it also introduces a cull factor in that mistletoe-infected trees produce 
a poorer grade of lumber than healthy trees. 


EFFECT OF MISTLETOE ON SEED PRODUCTION OF HOST. 


Pearson * has shown that, as a result of a collection in 1909, seed 
from mistletoe-infected black jacks gave a germination of 17 per 
cent below that of healthy black jack, which had a final germination 
of 78 per cent. The present study leads to the conclusion that, 


5 Pearson, G. A. The Influence of Age and Condition of the Tree Upon Seed Production in Western 
Yellow Pine. U.S. Dept. of Agri., Forest Service Cir. 196, 1912. 


26 BULLETIN 1112, U. S. DEPARTMENT OF AGRICULTURE. 


although the mistletoe may stimulate growth in that portion of the — 
host adjacent to the parasite, causing the abnormal development of 


certain limbs and branches into witches’ brooms, the excess of carbo- 


hydrates produced by the additional foliage of the mistletoe-stimu- 
lated branches is consumed by the parasite, thereby reducing the 
amount available for the seeds. The effect upon the host in all cases 
is insidious, slowly depriving the tree of its vitality instead of causing 
injuries in the nature of a shock, as in the case of burns and other 
mechanical injuries. In this and the following study, no informa- 
tion was-available as to the influence upon seed production of the 
condition of other trees which may have supplied the pollen for fer- 
tilizing the seed tree. Because of the lack of pollination experiments, 
the conclusions are necessarily based wholly upon the condition of 
the tree from which the seed was collected. 

In order to check this theory further, additional seed collections 
were made by the Fort Valley Forest Experiment Station in 1913 and 
1915 from mistletoe-infected and healthy western yellow pines. 
Aside from the difference in degree of mistletoe infection, the trees 
were otherwise normal and very similar in age and crown develop- 
ment. The seed extractions and germination tests were conducted - 
separately for each tree. Five hundred seeds from each lot were 
germinated in sand in the greenhouse at a temperature ranging from 
40° to 90° F., with a mean daily temperature of approximately 65° F 
Daily counts were made during the progress of the germination tests, 
which continued for approximately 50 days. 

The pertinent data on the seed production of 64 felled western yellow 
pine trees for the 1913 and 1915 collections are classified in Table 18, 
according to the degree of mistletoe infection. The best criterion by 
which to judge the relative seed production is believed to be the repro- 
ductive value of each tree or the total number of viable seeds produced 
per tree, which represents a convenient summation of the fundamental 
variables of seed production. This is obtained by multiplying the 
yield per tree in pounds of clean seed by the number of clean seeds 
per pound, and in turn multiplying the product by the final germina- 
tion per cent. It will be noted that, with the exception of the lightly 
infected class upon which the mistletoe appears to have a slight stim- 
ulating effect, there is a decrease in the percentage of germination, 
the yield of cones, and clean seed per tree and consequently a marked 
decrease in the reproductive value per tree with an increase in the 
amount of mistletoe infection. The reproductive value of the trees 
‘in the intermediate infection class is about 40 per cent of that of the 
healthy class, while the reproductive value of the trees in the heavily 
infected class falls to only about 25 per cent of that of the healthy 
class. This is not surprising when the effects of the parasitism are _ 
fully understood. The data for the mistletoe-infected classes of ‘a 


tei 


THE WESTERN YELLOW PINE MISTLETOE. = ae 


felled trees reported in Table 18 are meager because of the difficulty 
experienced in securing seed from mistletoe-infected trees, owing to 


the sterility of the cones and their failure to develop. In fact, a 
diligent search was made for heavily mistletoed trees which were 


_ bearing seed, but very few were found. 


‘Tape 18. Pati on the seed production of 64 felled western yellow pine trees classified 


according to degree of mistletoe infection. 


Yield per tree. 
Final | Clean xg Reprodue- 
Degree of infection. germina- seadss 1a Ye | stave walue Basis. 
tion. per pound. Cones: (i Glean seed: |. 2S tree. 


Number of | Number of 


ae collection: Per cent. MN umber. Bushels. Pounds. | viable seeds. trees. 
Ee aE a 82.8 14, 4 0.8 1.08 12, 942 4 
2 Se ee 84.1 14, 385 1.0 1.10 13, 292 2 
a ee 81.7 13, 314 Pi 45 4, 895 2 
See eee eee eee ST 8 77.0 14, 475 3 etl 3, 455 2 
Mean of x, xx, and xxx. 80. 9 14, 058 .6 . 62 7,052 6 
1915 collection: 
) SERS | eS eee 53.2 12, 156 1.1 . 83 5, 626 11 
Mean ofx, xx, and xxx. . 47.1 14,170 -9 .37 2, 202 4 


The extent and condition of the seed crop on the standing trees on 


_ the permanent sample plots were under observation from 1912 to 


1916 in order to secure additional data on the effect of mistletoe. 
infection on the amount and periodicity of seed production. The 
1912 seed crop was rather light; only a few of the trees bore any 


large quantity of cones. In 1913 there was an average crop, with 


practically none in 1914, while the 1915 seed crop was somewhat 
below the average. 

The records of the 1912 and 1915 seed crops for 90 of the living 
western yellow pines are classified in Table 19 by degree of mistletoe 
infection and amount of the seed crop. The seed crops were arbi- 
trarily classified by the observer as heavy, good, medium, light, or 
none. An analysis of the data shows that the amount of seed pro- 
duction varies inversely with the degree of mistletoe infection. As 


_ the degree of mistletoe infection increases the amount of seed pro- 


duced decreases until very little, if any, seed is produced by heavily 


infected trees. 


These results are further substantiated by observations of the 


_ writers covering a period of approximately 10 years. Trees heavily 


infected with mistletoe produce small amounts of seed at such times 
as there are generally heavy seed crops, and at other times practically 


_ none. The few cones that may occasionally be found on trees 
_ heavily infected with mistletoe are very often aborted, and are 
_ frequently infested with a cone insect (Conophthorus ponderose) ° 


§ Material determined by Office of Forest Insect Investigations, Bureau of Entomology, U. 8. Dept. of 
Agriculture. ; 


28 BULLETIN 1112, U. S. DEPARTMENT OF AGRICULTURE. 


TaBLeE 19.—Record of 1912 and 1915 seed crops for 90 standing western viettats pine trees 
classified by degree of mistletoe if saa and amount of seed crop. na 


Amount of seed crop. ae 
Degree of Total — 


infection. ‘| basis. 
Heavy Good Medium Light None «4 
Num- Num- Num- Num- P Num- 
1912 seed| berof | Per ber of | Per ber of | Per ber of | Per ber of | Per 
crop: trees. | cent. | trees. | cent. | trees. | cent. | trees. | cent. | trees. | cent. | Trees. 
Ce 0 0 2 5.3 23.7 27 71. 38 
0. Fs Rea 1 wn 0 1 As 30.8 a 53. 8 13, 
Sie saat <5 0 0 0 0 0 0 5 25.0 15 75.0 20 
0 -0 0 0 0 0 0 0 16} 100.0 16 
1915: “~ eed 
crop: 
Onsen 0 0 1 2.8 2 5.5 15 41.7 18 50.0 36 
Kase ce 0 0 0 0 2 14.3 5 35.7 7 50.0 14 
p<. CRIES 0 0 0 0 0 0 4 18.2 18 81.8 22 
poo 0 0 0 0 0 0 0 0 18} 100.0 18 


A similar deterrent effect of mistletoe on the seed production of 
Douglas fir, western larch, and lodgepole pine has also been found by 
Weir 7 to obtain in the Northwest, where seed collected from very 
old mistletoe brooms showed a germination on an average of 10 per 
cent below that of seed taken from uninfected branches of the same 
trees. Munns ® reports that Jeffrey pine trees infected with mistletoe 
had half as many more seed to the pound as were found in the cones 
on thrifty trees, but the germination was 20 per cent lower and the 
seedlings produced were not so vigorous. It seems very improbable 
that moderate or heavy mistletoe infection would ever act as a 
stimulus upon seed production, because its slow, insidious action 
makes constantly greater demands upon the vitality of its host. 
Trees moderately or heavily infected with mistletoe are prsinsens! of 
little or no value for the purpose of seed production. 

The fact is fundamental in silviculture that variations in the indi- 
vidual characteristics of the parent trees are hereditarily transmitted 
through the seed.*° The extent to which the origin of the seed influ- 
ences such characteristics as the resistance or immunity to disease, 
the rate of growth, and the growth-form of the regenerated forest, 
is of vital importance in the rational practice of scientific forestry. 

The experiments of Zederbauer '° indicate that trees grown from 
seed collected from intermediate, suppressed, and weakened trees 
are less resistant to disease than trees grown from seed produced by 
dominant and vigorous trees. The hereditary characters of the spe- 
cies are not changed materially during one rotation. Several gener- 
ations are necessary to show the true effects of those characteristics 

7 Weir, James R. Mistletoe Injury to Conifers‘in the Northwest. U.S. Dept. of Agri. Bul. 360, 1916. 

8Munns, E.N. Effect of Fertilization on the Seed of Jeffrey Pine. Plant World, 22: 138-144, 1919. 

9 Engler, Arnold. Einfluss der Provenienz des Samens auf die Eigenschaften der forstlichen Holzge- 
wichse. Mitteilungen der Schweizerischen Centralanstalt fiir das forstliche Versuchswesen, Ziirich, 1905, 


B. 8, S. 81-236; 1913, B. 10, s. 1-386. 
10 Zederbauer, E. Centralblatt fiir das gesammte Forstwesen, 1912, s. 201. 


THE WESTERN YELLOW PINE MISTLETOE. 29 


of the parent tree which may be transmitted through the seed, such 
as an unusual divergence from the typical silvical characteristics of 
the species. A clearer conception of the latent possibilities of dis- 


ease resistance and immunity of a species obtained through tree 


breeding is of vast importance in the silvicultural improvement and 
management of the forest. The hereditary influence of the parents 
upon the offspring is a well-recognized factor in genetics. This factor 
is doubly important in forestry, not only in the collection of seed for 
artificial regeneration, but also in the selection of seed trees to provide 
for the natural reproduction of cut-over forests. In timber-sale prac- 
tice only thrifty seed trees should be left and all diseased and sup- 
pressed trees should be removed in order to improve the condition of — 
the forests of the future. 


SILVICULTURAL ASPECT OF MISTLETOE INFECTION. 


The destruction caused by disease promises to approach or even 
surpass the losses from fire on the national forests of the Southwest, 
now that the development of fire protection has reduced the fire 
hazard. Mistletoe injury presents one of the most serious phases of 
this silvicultural problem. The parasite may be slow in effecting its 
injury, but it is unquestionably sure. 

A brief discussion of some of the salient objects of silviculture is 
essential to a complete understanding of the significance of any 


methods of control which may be attempted. The chief fundamen- 


tals of silviculture, as applied in the regeneration of western yellow 
pine stands, are to maintain the continuity of the forest and to 
increase its productivity. A number of basic considerations must 
be taken into account under any rational method of cutting, among 
which may be mentioned the silvics of the species, the fire hazard 
and liability, exploitation and economic conditions, and the removal 
of the decadent, unhealthy, and overmature timber as rapidly as 
possible, to avoid waste through decay. All defective, diseased, and 
suppressed trees should be marked for cutting unless needed as fire 
insurance or seed trees. No defective or diseased tree should be left 
standing if it is evident that it will not live until the next cutting, 
unless it is absolutely required for silvicultural purposes. When it 
becomes necessary to reserve trees among the large diameter classes, 
thrifty, healthy trees of good form should be selected, since the con- 
dition of the progeny is influenced by heredity as well as by soil and 
climate. Increased forest productivity will be realized if, in the 
application of the above principles, the forester will also strive to 
eliminate the deterioration of merchantable material. It is thus 
evident that the marking on each individual area must be varied to 
meet the silvicultural requirements of the forest. The importance 
_ of careful, intelligent marking on timber-sale areas can not be over- 


30 BULLETIN 1112, U. S. DEPARTMENT OF AGRICULTURE. 


estimated, since this is the practicable means by which rational silvi- — 
cultural management is actually secured. s 
Meinecke ! has suggested the establishment of pathological rota- — 
tions for species of economic importance which are subject to serious — 
diseases. A pathological rotation may be defined as the period during 
which the timber crop may grow and be subject to exploitation at a 
profit, but beyond which rapid deterioration is imminent and the 
product will be marketed at a great reduction in value. The patho- 
logical rotation is therefore a limiting factor; and, with regard to 
heartwood-destroying fungi entering the heartwood through open 
wounds, it is based upon the age of decline or the age at which even 
unwounded trees become subject to heavy infection because they are 
unable to throw off the parasite or to hold its growth in check. From 
the discussion in the earlier part of this bulletin it will be seen that 
the mistletoe may kill small seedlings only a few years old, as well as 
veteran western yellow pines 200 to 300 years old. It is therefore 
evident that it would not be practicable to attempt to establish a 
pathological rotation for mistletoe-infected western yellow pine. 


CONTROL OF MISTLETOE. 


Any method of control of this serious and widely distributed enemy 
of the western yellow pine forests of the Southwest must be adapted 
to existing conditions. As in the case of other diseases, prevention 
is the basis for control. The protection of healthy stands of timber 
from disease is accomplished mainly by removing the source of 
infection. | 

Mistletoe is more susceptible to control measures than many fungi. 
Infection is confined to the aerial parts of the host, while fungi may 
infect the subterranean as well. The seeds of the mistletoe, which. 
are much larger than the microscopic spores of fungi, are not subject 
to such wide dissemination. Mistletoe is killed with the death of its 
host, whereas certain fungi may remain alive for an indefinite period 
following the death of their hosts. 

It is evident also that mistletoe develops rapidly after cutting, 
since many of the trees left standing on the permanent sample plots 
were killed by mistletoe during the five years following the logging 
operation; and many more, although still alive, will die in the course 
of a comparatively few years. In this study mistletoe was found to 
be directly or indirectly responsible for the greater number of deaths — 
of western yellow pine. 

All of the facts at hand indicate that the cutting of mistletoe- 
infected trees is the only practicable method of control. Since 
mistletoe appears to spread more rapidly and to grow faster on 
lightly infected trees, as a result of increased wind and light following 


11 Meinecke, E. P. Forest Pathology in Forest Regulation. U.S. Dept. of Agri. Bul. 275, p. 59, 1916. _ 


THE WESTERN YELLOW PINE MISTLETOE. 81 


cutting and providing more favorable conditions for the optimum 
development of the parasite, every effort should be made to free the 
stand entirely of mistletoe infection, although it is doubtful whether 
in certain cases the removal of lightly infected trees would be war- 
ranted because of silvicultural reasons. The increased activity of 
the mistletoe following the opening of the stand militates against 
leaving for a future cutting operation any but lightly infected trees, 
the infection of which is confined to the lower portion of the crown. 
Old and heavily infected trees should be cut for two reasons: (1) To 
improve the hygienic condition of the forests of the future through 
the removal of the mistletoe, and (2) to secure the maximum reali- 
zation on a rapidly diminishing growing stock or forest capital. 
Since the future productivity of the forests depends to'a great extent 
upon the proper choice of seed trees or of the seed itself in the case of 
artificial regeneration, those trees used for reproductive purposes 
should be sound, healthy, and of an intermediate age class. 

As heavy a stand of healthy trees as possible should be left in order 
to compensate for the removal of diseased trees, and to maintain 
better forest conditions, reduce wind damage, and insure a denser 
stand of reproduction. Exceptional care should be taken to leave 
every healthy black jack which is free from infection. Wherever 
possible, trees should be freed from light infections by cutting off 
lower branches within reach. Transition trees and vigorous yellow 
pines, suitable for seed trees, should be left in greater numbers to 
take the place of diseased black jacks removed, to maintain better 
forest conditions, and to furnish abundant seed for the restoration 
of the stand. Small heavily infected black jacks should be marked 
wherever it is possible to have them cut under the sanitation clause 
of the timber-sale contract, or where there is a market for small 
material, such as stulls, mine props, ties, poles, posts, and pickets. 

Forest officers in charge of marking on mistletoe-infected timber- 
sale areas should study carefully the possibilities of increasing the 
number of healthy trees in the remaining stand. The pruning of 
infected limbs from small trees at the time of marking presents a 
practical means of eliminating light limb infections and at the same 
time increasing the number of healthy trees. Occasionally there are 
trees in a stand that are lightly infected on a low branch within 
reach of the ground. Mistletoe-infected reproduction and young 
timber below merchantable size should also be freed from the disease 
either through cutting the seedlings and saplings or by lopping off 
the infected branches. Such measures may be impracticable except 
on timber sale areas and in some cases the extra labor and expense 
involved may prove prohibitive. 

_ The areas of mistletoe infection should be located and mapped as a 
prerequisite to an efficient control campaign. The degree of injury 


32 BULLETIN 1112, U. S, DEPARTMENT OF AGRICULTURE. 


and the amount of infection should also be recorded. Weir has q | 


suggested that this could easily be done by timber-survey parties in | 


connection with their regular mapping and cruising work. Such 
tangible records of mistletoe infections would be invaluable to forest — 
officers in showing just where diseased stands are located, in order 
that an attempt be made to exploit stands of seriously diseased tim- 
ber as rapidly as possible. 

The advent of a large commercial timber-sale operation should se 
be awaited before undertaking mistletoe-control work. Small ranger 
sales and even the issuance of free-use permits would materially assist 


in the reduction of severe infections. Although in many instances ~ 


the large lumbering operation is more economical than the small one, 
the latter can render a definite service in improving the hygienic con- 
dition of the forest through remoying more or less isolated infections 
which are too small to be exploited in a large operation. The prod- - 
ucts of the small operation are not marketed in such highly finished 
or specialized form as are many of the products of the large operation. 
In the case of a small lumbering operation mistletoe-infected trees 
will, in almost every case, be as well adapted to the desired uses as the 
sees of healthy trees. 

The problem of the control of mistletoe assumes two quite different 
aspects, depending upon the degree of infection on a given area. 
Silvicultural systems of regeneration should provide for the eradica- 
tion of the mistletoe from the stand as one of the most necessary re- 
sults to be accomplished. On areas adequately stocked with advance 
reproduction all infected trees should be cut. On the other hand, on 
areas of light to moderate infection special emphasis should be laid 
upon the need of leaving all healthy trees possible, even if they belong 
to the “‘yellow-pine’’ class, in order to insure as good a condition of 
the forest cover and seed production as possible. Where the injury — 
is not very serious the marking rules should call for the removal of all 
mistletoe-infected trees possible without breaking up the continuity 
of the stand or materially interfering with the silvicultural system 
of management adopted for the area. Lightly infected areas should 
be marked in such a manner that, with supplemental pruning at the 
time of marking, the stand would be practically free of infection. 
Lightly infected black jacks and transition trees on areas bearing no 
advance reproduction should not be cut when otherwise thrifty and 


sound, except where thinnings are desirable to obtain increased growth —__ 


or where reproduction is established. Such thinnings, however, may 
be somewhat heavier than in uninfected stands; but in lightly in- 
fected black-jack stands where reproduction is not established vigor- _ 
ously growing and thrifty trees should not be radically sacrificed. — 


13 Weir, James R. Some Suggestions on the Control of Mistletoein the National Forests of the North- a 
west. Forestry Quarterly, 14: 567-577, 1916. } 


THE WESTERN YELLOW PINE MISTLETOE. 33 


Lightly infected yellow pines should be left when uninfected trees or 
lightly infected black jacks are not available for seed and protection. 

Moderately infected trees should always be marked for cutting, 
except where there are no other trees available to leave as seed trees. 
Mistletoe can not in all cases be eliminated in one cutting without. 
too great a sacrifice of silvicultural requirements. Moderately 


_ infected trees should not be left for seed on lightly infected areas if 


healthy trees are available within 100 yards. This, however, applies 
to large areas rather than to small openings or small areas which have 
a chance to seed in from surrounding trees and where infection might 
be removed completely without opening the forest.too extensively. 
Moderately infected trees should be left for soil-protection purposes 
only on the most adverse sites, where their need for this purpose is 
clearly evident. 

Areas of heavy infection on which the injury from mistletoe is 
alarming should receive special attention and should be treated from 
the standpoint of the sanitation of the forest. Areas where the 
entire stand is too heavily infected to permit carrying out sanitation 
measures without material interference with the silvicultural require- 
ments of the forest should be marked for clear cutting. In practice 
such a condition will seldom be encountered. The largest possible 
number of small trees infected with mistletoe should be utilized. 
Areas of unmerchantable reproduction infected with mistletoe should 
be freed of the disease either through cutting the diseased seedlings 
and saplings or by pruning off infected branches. In certain cases it 
would be desirable for the owner of the forest to devote special funds 
for mistletoe-control projects, as is done in the case of serious insect 
_ infestations. 

While the areas infected with mistletoe to such an extent that 
diseased trees must be left or the stand practically clear cut, are not 
extensive, areas will probably be found on which forest planting to 
fill in blank growing spaces will be desirable following operations 
approaching a clear cutting under a mistletoe-control project. It 
may also be advisable from the standpoint of economy to clear-cut 
and plant certain limited areas of heavy infection. A definite policy 
of mistletoe control should be adopted for mistletoe-infected areas 
to be cut over by timber sales. Necessary funds should be provided 

to complete the cleaning of the areas after.the operator has removed 
all of the diseased trees which he can be required to take under the 
agreement. 
Forests in the vicinity of nurseries and planting areas should 
_ present unusually healthy conditions. It should be remembered 
_ that healthy trees can not be grown in an insanitary environment. 


_ All mistletoe infection in the vicinity of forest nurseries and planting 


areas should therefore be removed. 


34 BULLETIN 1112, U. S. DEPARTMENT OF AGRICULTURE. 


When a proposed timber-sale area contains a considerable amount __ 


of mistletoe, a special mistletoe sanitation clause should be inserted 
in the contract, containing the stipulation that all heavily infected 
trees, whether merchantable or unmerchantable, and certain other 
moderately infected trees will be marked for cutting. If the amount 
of unmerchantable infected timber is sufficient to affect the stumpage 
price materially, this factor should be fully taken into consideration 
and due allowance made for it in the stumpage appraisal. 

In control work on those areas where both mistletoe and insects 
are present, it would be advisable to combine the eradication of 
both pests where the commercial value of the stand justifies such 
measures. Infestations of secondary bark borers have occasionally 
been found and reported with or immediately following mistletoe 
infection.* It is believed that certain of these insects even show a 
slight preference for trees infected with mistletoe. The attack of 
trees weakened by the mistletoe often hastens their death, or in the 
case of dead trees the work of the borers hastens deterioration. : The 
control of such combined infection and infestations by eliminating 
the weakened trees would tend to control both mistletoe and insects, 
and thus hasten the realization of the ideal—a productive, thrifty, 
and healthy forest. 

The western yellow pine mistletoe probably has few natural enemies 
which can contribute toward its control. During the course of the 
studies reported in the preceding pages, a spittle insect (Clastoptera 
obtusa)’®> was very frequently found within masses of spittle on the 
mistletoe plants. The work of the insect in controlling the mistletoe 
is probably of little practical importance.- However, since the 
insect subsists on the juices of the mistletoe, it must tend to weaken 
the mistletoe to a certain extent, especially in cases of severe infes- 
tations. 

Through a proper realization and appreciation of the necessity 
for adequate control measures and their adoption on all cutting 
areas where the amount of mistletoe infection is relatively great, a 
very good beginning can be made toward the eradication of the 
pest through the more or less gradual process of elimination. 


SUMMARY. 


Western yellow pine is subject to severe injury by mistletoe 
(Razoumofskya cryptopoda). The injury to the forest caused by the 
insidious and destructive action of this pest results in serious losses 
of western yellow pine and presents one of the most important 
silvicultural problems in the Southwest. ; 


14 Hopping, Ralph. Insect Infestation in Relation to Injury, Fungi, and Mistletoe. Manuscript report. 
February 24, 1915. 

15 Determined by E. H. Gibson, Scientific Assistant, Bureau of Entomology, U. na Department of 
Agriculture. 


THE WESTERN YELLOW PINE MISTLETOE. 35 


Mistletoe infection causes a marked decrease in the rate of growth 
of the host, which continues until the virulent parasite ultimately 


| causes the death of the tree. The rate of decrease varies directly with 


_ the degree of infection from little or no decrease in the growth of 
~ lightly infected trees to a very marked falling off in the current 
growth of heavily infected trees. Many trees are killed annually by 


' this pest alone or in conjunction with other causes, such as insect 
infestations or porcupine injury. 


The decrease in the rate of diameter and height growth and the con- 


_ sequent current increment of trees infected with mistletoe are accom- 


_ panied by a reduction of the leaf surface of the host. 
Trees of all age classes are subject to mistletoe infection, provided 
_ the seeds of the parasite fall on parts of the tree which are not pro- 
tected by the bark. Young seedlings and saplings usually die com- 
paratively soon after becoming severely infected, while older trees 
_ May remain alive for a much longer time. 
_ The quantity and quality of the seed produced by trees infected 
with mistletoe is below that of normal, healthy trees. Heavily 
_ infected trees are practically worthless for peal production and should 
not be left as seed trees 
_ The most practical method of controlling mistletoe is to remove 
_ the infected trees while cutting operations are in progress. All heav- 
_ ily infected trees should be marked for cutting. Moderately infected 
_ trees should be marked for cutting except where others are not 
available for seed trees. On areas of light to moderate infection the 
marking rules should require the removal of all mistletoe-infected 
_ trees possible without breaking up the continuity of the stand or 
_ materially interfering with the silvicultural requirements of the forest. 
_ Exceptional care should be taken to leave as heavy a stand of healthy 
trees as possible in order to compensate for the removal of diseased 
_ trees and to maintain better forest conditions. 
Areas on which the entire stand is too heavily infected with mistle- 
_ toe to permit adequate sanitation measures without very material 
- interference with the silvicultural requirements of the forest should 
be marked for clear cutting under a mistletoe-control project. 
_ Although in actual practice such a condition will seldom be encoun- 


_ tered, relatively small areas will probably be found on which forest 


_ planting may be desirable. 

When proposed timber-sale areas contain a great amount of mistle- 
toe, a sanitation clause should be inserted in the timber-sale contract 
_ requiring the cutting of all heavily infected trees, whether merchant- 
able or unmerchantable, and certain other moderately infected trees 
_ which may be marked. 


ORGANIZATION OF THE UNITED STATES DEPARTMENT OF 
AGRICULTURE. 
PS COPGIAEY DOF: AQTIOUIUPE no ois oo oe ag oe le eee ep Henry C, WALLACE, 
A SSIBLET DOTY «6 — nin cw nig > op ae so  e . C. W. Puastey. 
Derector of Stventepie Works. Ma. koe oe ee K. D. Ban. 
Director of Regulatory Work. .....:-.-.----..+-. me ee, 
Weather Bureaus... dees enh ey cead Duet a CHARLES F. Marvin, Chief. — 
Bureau of Agricultural Economics. ......------ Henry C. Taytor, Chief. 
Bureau of Animal dndystry cin: be 3: ees oem JouN R. MonzeEr, Chief. 
arene of Llane, INMUsty : «wie cones 5 2 ee Writam A. Taytor, Chief. 
DHERE TUES na e's See eke re aoe oe W. B. Greetzy, Chief. 
Burews of Chemistry: 2? . s/229E OTT A WALTER G. CAMPBELL, Acting Chief 
Bureau of Sots... 252 Lok Ins “ae Mitton WHITNEY, Chief. 
Bureau.of Entomology: «5.22045 - 208 dyes wet de L. O. Howarp, Chief. 
Bureau of Biological Survey.....-..------+--+-- EK. W. Netson, Chief. 
Here OF PubuCe ROGISs.\. ngg oko ek oe hase THomas H. MacDonarb, Chief. 
Fixed Nitrogen Research Laboratory. .......-..-- F. G. Corrrety, Director. 
Division of Accounts and Disbursements......... A. Zapponr, Chief. 
Dwision'of Publications.d 2i i). ciiletiewes ik Joun L. Cosas, Jr., Chief. 
TAbrapy 1 Jo's nies ehrigge tein che geree secs teen e. CLARIBEL R. Barnett, Librarian. . 
States Relations Servwle ss» mn sotninivie ns “ein <b. snk A. C, True, Director. 
Federal Horticultural Board...........-.------- C. L. Marzart, Chairman. 
Insecticide and Fungicide Board. . ..-------- J. K. Haywoop, Chairman. 
Packers and Stockyards Aamenstlation BAL AS: PON Pe MorriLt, Assistant to the 
Grain Future Trading Act Administration......) Secretary. 
Office bf the Soutitor 50:94:35 sew sheews- meh eres o8 R. W. Wi11aMs, Soutcrror. 


es bulletin is a contribution from— 


Forest SCrviee. 05.08 oo Ss OL Sa W. B. GREELEY, Chief. 
Branch:of Lends: «ca astinn ded teens L. F. Kyetpp, in charge. s 
Buresu of Plant Andustry c-.veb «t-aecintasies onyiees Wit1ram A. TAYLOR, Chief. 
Investigations in Forest Pathology. . . HAVEN MercaLr, in charge. ae 
367 P 


ADDITIONAL COPIES 
OF THIS PUBLICATION MAY BE PROCURED FROM 
THE SUPERINTENDENT OF DOCUMENTS 
GOVERNMENT PRINTING OFFICE 
WASHINGTON, D. C. 
AT 
15 CENTS PER COPY 


V 


UNITED STATES DEPARTMENT OF AGRICULTURE 


BULLETIN No. 1128 


Washington, D. C. PROFESSIONAL PAPER February 20, 1923 


DECAYS AND DISCOLORATIONS IN 
: AIRPLANE WOODS. 


By J. S. Boyce, Pathologist, Office of Investigations in Forest Pathology, 
Bureau of Plant Industry. 


CONTENTS. 
Page. Page. 
PTO ICETO Wise era 1 | Discolorations caused by fungi —~____ 24 
General considerations _____-__--~_- 2 Seles enieeee Meee RN eee 25 
Woods used for airplane construction_ 3 Brown-oak discolorations —___~ ~~ 29 
General defects of airplane woods___ 5 Decay discolorations .____-____ 30 
aor? commarisons-_?<_.....+-=___—— 14 | Decay in finished airplanes ________ 40 
Discolorations caused by wounds__-_ 5 LE AEST 0 0072 yy a a a a 42 
Lightning wounds ~___--_--_-~--_ Li i iberabureleipedmen mene fee maar 45 
Sapsucker wounds -~-__-_-_+_~ 20 | Defects of wood referred to in this 
Pitnerayyiecks 2223. 222.222 20 bulletin, arranged by species____ 50 
Chemical discolorations _____----~-~- 23 
INTRODUCTION. 


The purpose of this bulletin is to enumerate and describe the more 
important decays and discolorations to which woods used in air- 
craft construction are subject and the conditions under which they 
occur. It is well known that the initial or incipient stages of decay— 
that is, the first steps in weakening wood—are indicated by discolora- 
tions, but wood is subject to many color variations from the normal 
not caused by wood-destroying fungi. 

The value of recognizing the true nature of any given discolora- 
tion or other abnormality is immediately apparent, since such know]l- 
edge will permit the free use of wood which, though seriously reduced 
in value from an esthetic standpoint by a disagreeable discoloration, 
is not mechanically weakened, while at the same time dangerous color 
variations can be detected. In the airplane industry, where the very 
finest quality of high-grade wood is demanded, and in which there is 
a maximum of unavoidable waste in the remanufacture of the lum- 
_ ber, it is imperative that no suitable material be wasted or diverted 
to another purpose, while at the same time it is equally important 
_ that all weakened material be excluded. 

This bulletin first considers certain defects in airplane woods not 
_ due to decay, but which must be readily recognized in order to avoid 


9997T—23 1 1 


2 BULLETIN 1128, U. S. DEPARTMENT OF AGRICULTURE. 


confusion. Next are described the various discolorations in airplane 
woods caused by mechanical injuries to the living trees, chemical 
reactions, harmless fungi, and decay-inducing fungi in relation to 
their actual effect on the strength of wood. In the case of those 


defects and properties which it is not within the province of this 
bulletin to discuss in detail, references to available literature are 


given. 
GENERAL CONSIDERATIONS. 


There are certain basic principles in the manufacture of high- 
grade lumber which should be most rigidly adhered to in the case of 
stock for airplanes. The purchaser should be certain that the manu- 
facturer supplying his requirements is both willing and able to fulfill 


these conditions, so that defects very difficult to detect are not intro- — 


duced. 

When trees are felled the logs should be removed from the woods 
with reasonable promptness, because as soon as the timber is down 
it becomes subject to decay, sap-stain, checking, and the attacks of 
wood-boring insects. Leaving logs in the woods over winter is par- 
ticularly poor practice. If the logs must be stored for any consider- 
able length of time they should be kept in the pond, where the defects 
mentioned will be largely prevented. > 

After the logs are sawed the lumber should be carefully inspected: — 
and those pieces unsuitable for use in airplanes diverted to other 
uses. Next comes seasoning. Drying with artificial heat in dry kilns 
is preferable. The kilns should be of proper construction, so that the — 
temperature and relative humidity can be completely controlled and ~ 
the lumber brought to an average final moisture content of about 8 
per cent, within the limits of 5 to 10 per cent (based on oven-dry 
weight), without checking or other injury. If it is necessary to store 
the dry lumber at the mill it should be placed in a dry shed, com- 
pletely protected from the weather. The shed should have a board 
floor. Concrete, particularly if new, or dirt floors may give off con- 
siderable moisture. The stock should be shipped in box cars com- 
pletely protected from moisture. When it reaches the factory the 
lumber should be shop seasoned; that is, placed in a room under 
uniform shop conditions, for about two weeks. During the entire 
process of manufacture the stock should be carefully protected from 
the absorption of moisture. Piling lumber or partly fabricated parts 
on damp floors or under the drip from steam or water pipes are two 
not uncommon offenses. : 

In case it is impossible to kiln-dry the stock, air drying must be 
resorted to. As a rule it is not possible to get the moisture content 
below 11 per cent by this process, except in arid regions. When 
the lumber comes from the saw it may be necessary to dip it ina © 
chemical solution to prevent sap-stain in regions where lumber is ~ 
especially subject to this discoloration; but under any conditions — 
the stock should be carefully open-piled on elevated foundations to ~ 
assure a circulation of air throughout and only sound, bright, — 
thoroughly seasoned stickers used between courses. The piles should — 
be properly slanted and roofed, so that rain will run off and not soak 
the lumber. To pile lumber closely, without proper circulation of air 
throughout the piles, results in some cases in warping, sap-stain, 


DECAYS AND DISCOLORATIONS IN AIRPLANE WOODS. 3 


and, ultimately, decay. Then, too, it is almost impossible for the 
stock in the center of the pile ever to become properly dry. 

At best, however, air drying is a matter of months, even with soft- 
woods, while proper kiln drying can be accomplished within one to 
three weeks or so, depending on the thickness of the stock. As a 


rule, hardwoods both kiln-dry and air-dry more slowly. 


Air-dried stock should be shipped in the same manner as kiln- 
dried and handled in the same way at the factory, except that it 
must be kiln-dried to the proper moisture content before it is condi- 
tioned in the shop. ; 

The principles given briefly in the foregoing paragraphs, together 
with their application and underlying reasons, are brought out in 
detail in the following pages. 


WOODS USED FOR AIRPLANE CONSTRUCTION. 


The most important wood for aircraft construction is spruce, 
including red, white, and Sitka spruce (Picea rubens Sarg., P. cana- 
densis (Mill.) B. S. P., and P. sitchensis (Bong.) Trautv. and 
Mayer), but of these Sitka spruce, on account of its much larger 
size and the consequently greater quantity of clear lumber that can 
be obtained, is paramount. By far the greatest proportion of the 
lumber entering into the construction of most present-day airplanes 
‘is spruce or one of its substitutes. The combination of strength 
properties with light weight found in spruce is not duplicated in any 
other wood. Most of the beams in the directing surfaces are prefer- 
_ably of spruce or a soft wood, as are many of the struts, and these 
parts account for the bulk of the timber in an airplane. 

An excellent substitute for spruce is Port Orford cedar (Cham- 
aecyparis lawsoniana (Murr.) Parl.), which is slightly heavier. 
Unfortunately the supply of this splendid wood is decidedly lim- 
ited. Douglas fir (Pseudotsuga taxifolia (Lam.) Br.), though much 
heavier than spruce, is an extensively used substitute. Other woods 
_ which can play some part’in this way or may be used for special 

purposes where a softwood is needed are western white pine (Pénus 
_monticola Dougl.), sugar pine (P. lambertiana Dougl.), western 

hemlock (7'suga heterophylla (Raf.) Sarg.), white fir (Abies con- 
color (Gord.) Parry), amabilis fir (A. amabilis (Loud.) Forbes), 
noble fir (A. nobilis Lindl.), yellow or tulip poplar (Lirzodendron 
tulipifera Linn.), basswood (Tilia americana Linn.), incense cedar 
. (Libocedrus decurrens Torr.), and western red cedar (Thuja plicata 
Don.). Certain parts of an airplane frame as a rule are made from 
hardwoods. In such parts great strength and toughness are re- 
quisite. Here, commercial white ash? stands supreme. For ex- 
ample, it is unsurpassed for longerons in those fuselages not con- 
structed wholly or mostly of veneer. Black ash (Praxinus nigra 
_ Marsh), which does not possess sufficient stiffness for use in highly 
_ stressed parts, can be distinguished from white ash (2, 30, p. 47; 68, 
_ p. 62).2. White oak,? hard maple (Acer saccharum Marsh), and 


-17Commercial white ash includes white ash (Frazinus americana Linn.), green ash (F. 
fea Borkh.), blue ash (F. quadrangulata Michx.), and Biltmore ash ( F. biltmoreana 
eadle). 
Sean numbers (italic) in parentheses refer to ‘‘ Literature cited” at the end of this 
etin. 
* White oak as used here includes white oak (Quercus alba Linn.), bur oak (Q. macro- 
carpa Michx.), cow oak (Q. michauzii Nutt.), and post oak (Q. minor (Marsh) Sarg.). 


4 BULLETIN 1128, U. S. DEPARTMENT OF AGRICULTURE. 


rock elm* are sometimes used instead of white ash. Hickory,°-so 


far, has been principally used for tail skids. The two finest woods — 


‘for propellers are black walnut (Juglans nigra Linn.) and true 
mahogany (Swietenia mahagoni Jacq.), also known as Centrai 
American mahogany. Other species commonly used are yellow 
birch (Betula lutea Michx. f.), sweet birch (B. denta Linn.), Afri- 
can mahogany (A haya senegalensis A. Juss.), black cherry (Prunus 
serotina Ehrh.), hard maple, white oak, and yellow poplar. How- 
ever, a number of other woods are occasionally utilized, and in the 
future a wide variety of species will probably be admitted. Euro- 
pean designers even now are less exacting in this respect, sometimes 
using two species of wood in the same propeller, which on the 
whole is considered poor practice in this country. 


TABLE 1.—Distribution of wood in airplanes, showing the service requirements 
and the adaptation thereto of the different grades of the several species. 


Species of wood and quality designation (grade). 
lo ! ; ro ® 
Las] fe . j=" eo | . H j = 
iS) q slew] a | x : 
Designation of assembly and name of part. ¢ a & Ps 3 Os] A a os Bs s & A 
o 3 | 
SBCs] s le8 S| Slog 2 /2lala/s 
R/S 18° 2is |8| 8 esis|s|alsie 
aials (ae |F\FR EE a \a lm 
Main and center planes, ailerons, stabilizer, | | ; 
elevator, rudder, and fins: | 
Beams; solids. 6 2 = 25 So See ee A. | A | Al... A} A | Ay lppAps SS eee 
Beals): POX. Pa ess oe Cee eee eee A |} ATA J....) ACA dco AS eee eee eee tg 
Filler:blocks..5:3.25 2.2 tj: me car, See eer ee C| C}.C1C) COs) 40) Gao ee eee 
MilletStrips:.c. ace. nee nae See eee nee B|B)B |B B YB Ss Pa eee 
Panel blocks— 
oe ners SPS SAS ee EA 
orner blocks 4.5 454 et) 2. ae 
Spacer blocks.-focc8- ee Ae eS C/C) CC) 0) 0) OC) Gi eta aaa 
Remiorcine: DlOCKS. -< 5 Tesh Ws eee | 
Rib webs, solid. -....--..--.-.-----+---+----+- B.|B| BB |B | Buh B ceeeeteree eee ~ 
Rib webs, compression (s.lid)--....-.-.-.. A | Ad A.) A | Awl Al) Aen) Stee eee 
Compression struts.........-.-.--.------.. A) Ap AC...) Aby CAR) Aoe Soi Pee Se1 8 Ss igesha AeLe 
CAPEDMDS: atte: Jatt fee A 7A | A.) AL|CAC) Aes. Sos See if. 
Trailing edge— | ) 
Sirpieht:s: ~-<f- co bees se poe eee By ivBairB B | B | Bi :Bels- celeve at eee 
Bout +. 25-2. Co eae: ae ee ae eee eee ASP eee eee es. ne PY Sy eh tl = eT 
Entering edge— | 
SA Pee jeepers B.| B | B.|....| BB Be eee 
Bar eee ce eee tee ee LA ae wlecec}eceu|2 ana] bows) iene aaa rnin 
Gussets.....-. 50-4 eee eee eine ee es dee tne B|B|B .| B | B |. &.\ecndlesea aches 2a. 
Masts 224. cc = bp os eae eee eae eee A. Rel A | A | AR . 
Stringers 2. J.-L) - Ae Se eee ee .|. BB SB) (Baie OS error 
Interplane struts. 36:25 ten aoe ee A tee ae es oes a As | Aol ho) o 
Center section struts-. 2 222A | A} AS ACRONIS ee AT RAR ARE 
Fuselage: 
Longerons— 
Strangle xc) bi. 162 ed: eee et A } A>) AY. Sch eee A Age 
Betis | ee oe re Meme | aie s [ne a bovwecall cece 2 ae ee ee Aal Biel sae 
Struts, vertical, and horizontal— / 
« Highisttess 4.5 -2-b pps me cep ig ves |} A | A | Al...) A> Ael Al) ASU ES Staee 
SUOW SULCSS- ccc. Se ee es ree nee en ee |B! B| B....) BBY Bale eee eee 
Struts, diagonal: 42722 >- - 453-4. 6542 a5 ee B | BB |-2.2| Bo) BBs Bea eee ees 
SUpporis, N€AV Y= -. == Ho ten ee A|A|A|....| A | A) Al ASS 
Supports, light 229 3.52 fas sae ae a B|B| BB) B| BB) Bie eee 
Braco. blocks:<.J2-4-95--gee-uct= 55 eee B B B|B|)B| BBY) Bae 
NtMLCNETS. vows sere cect ae mea eee B B) B BY) Bl 3 a eee ee 
Cleats: i 228 32 betes ee eee ee ee es ee ee ee elise cfm .| CC} CC] C 
Wuarrene SUS << 2c wee 2 ee ee ee B\|B|B|B|B| 8 | 8) See 
Hioor and seat boards...2s22 teh l ese. ese C} Cj\-C}-Cy CC) CO i aaa eee eee 
Oradle slats 2-2. 28s oS oot Ci Ci} CC). C 1.C:) Cl tC Cs ee ae 
Seat rail.....-. BE 2 SO MNO kh tt Rs & A;A/A|A | Al ASA TSA eee a 
Dail Postsl.;s2 22. -.3 sates. pease eee Awl A ch cAt le eelaed 3 Se ee A NPA NEAL Re: ee 
Vall SKIG. ooo cic en ve castes waene sees nena sof aein al eee <eee ieee ee AY a Be ee 
Landing chassis: . 
ShNBES 5. seh. o 7 bee be pee a ie ee A tA) Ayal: Ne ee A | At Aiea 
Streamlining. Oe doe setae eee ee eee 1 C} CC] Cj Cl Cy) Cit GS eee eee 


‘Rock elm includes rock elm (Ulmus racemosa Thomas) and the more dense stock of 
both white elm (U. americana Linn.) and slippery elm (U. pubescens Walt.). 

®* The true hickories include mockernut hickory (Hicoria alba (Linn.) Br.), shellbark 
hickory (A. laciniosa (Michx. f.) Sarg.), pignut hickory (H. glabra (Mill.) Br.), and shag- 
bark hickory (H. ovata (Mill.) Br.). 


= 
t 


i 


on ) 


sacs cits sa heehee Re Nia a ideal Da, 


DECAYS AND DISCOLORATIONS IN AIRPLANE WOODS. 5 


Table 1, which is an adaptation of specification 15037-B of the 
Bureau of Aircraft Production, shows where the various woods 
may be used in an airplane and the quality desired. The symbol A 
indicates a grade of wood of the very highest quality and free from 
all injurious defects; grade G demands a quality of wood similar to 
grade A in all respects except that a little tolerance is allowed in 
regard to straightness of grain and specific gravity; wood of grade 
( is used in parts where little strength is needed and may contain 
various defects, provided the piece is strong enough for the purpose 
intended. 

These woods are not the only ones used for airplanes, but they are 
the most important. Others are mentioned here and there in this 
bulletin. It can be predicted that, with a growing scarcity of the 
more desirable species and an increase in our knowledge of the prop- 
erties of other species, woods little or not at all used at present will 
become of importance. For a full discussion of this entire subject, 
the reader is referred to other sources (60, 69, p. 34-40). 


GENERAL DEFECTS OF AIRPLANE WOODS. 


It is impossible to thoroughly understand wood without a work- 
ing knowledge of its structure and mechanical properties. This is 
more difficult to attain than with most other materials of construc- 
tion, for wood, instead of being a relatively simple and more or less 
homogeneous compound, is a highly complex organic structure whose 
chemical composition is even now none too well understood. The 
discussion in the following pages will be much clearer to the reader 
provided he has such knowledge. There are a number of valuable 
publications which may be referred to in this connection (30, 45, 47, 
48, 68, 69). 

Besides decay, there are other defects which reduce the strength 
of timber, and these must be given due consideration. Wood may 
be inherently weak because of its structure, it may be injured by 
Some process of manufacture, or the trouble may be due to faulty 
design or assembly. Such defects in relation to airplane woods have 
been discussed in various publications (42; 46, 68, p. 15-20; 69, p. 
11-22), but a review of the more important of these is essential 
here, since by the uninitiated some of them are confused with decay. 


GRAIN. 


One of the most common defects in airplane woods is an exces- 
sive slope of diagonal or spiral grain. Since any deviation from 
straight grain is accompanied by a reduction in strength, the re- 
quirements in this respect are very exacting, a deviation from 
straight grain of more than 1 inch in 20 inches rarely being allowed 
for any highly stressed portion of an airplane, although this may 
be reduced to 1 inch in 12 in portions of less severe stress. A dis- 
cussion of the methods to be employed in detecting this defect, to- 
gether with its effect on strength, may be found in several publica- 
tions (31; 42, p. 8-14; 68, p. 15-16; 69, p. 11-20). 

SPECIFIC GRAVITY. 


Brashness or brittleness in wood is another common defect. These 
Synonymous terms denote a lack of toughness in wood to which they 


are applied. Brash wood is usually low in strength, and when 


6 BULLETIN 1128, U. S. DEPARTMENT OF AGRICULTURE. 


tested by bending fails with a short break instead of a splintering 
fracture. This is one indication of decay, but not all wood show- — 
ing such defect is decayed. ‘Too often when wood appears to be ~ 
somewhat brash and develops less than the normal strength, instead 
of making a serious attempt to determine the real source of the diffi- 
culty the “cabalistic term “dry-rot” is uttered, and the case is set- 
tled, often resulting in the loss of good material, while the trouble 
oes on unchecked. Even if the wood be decayed, it most probably 
is not dry-rot, which term to the pathologist embraces a definite type 
of decay caused by a certain fungus. Let us consider a few of the 
more important causes of brashness, aside from decay, in aircraft 
woods. 

The primary requisite of wood for use in airplanes is that it 
must be of specific gravity high enough to give the necessary 
strength. It has long been known that an increase in strength of 
any species of wood goes with an increase in specific gravity, and 
it has finally become possible accurately to express this relation for 
the various strength properties, so that if the specific gravity of a 


given piece of wood is known it is possible quite accurately to derive 


its strength under various stresses (47). No matter how perfect a 
piece may be in other respects and free from all other defects, if it 
is below the minimum specific gravity it should not be used. ‘These 
minimum figures have been carefully worked out for the more im- 
portant airplane woods (68, p. 21; 69, p. 26). Wood of low specific 
eravity is naturally somewhat brittle, and for this reason is often 
erroneously considered as slightly decayed. While the actual spe- 
cific gravity of the wood substance in various species is practically 
the same (/3), having a value of 1.54, the porous nature of the wood 
is such that most commercial species range from 0.3 to 0.6. In other 
words, only one-fifth to three-fifths of a unit volume of wood is oc- 
cupied by wood substance; the remainder is air. 

It is self- evident that a density or specific gravity determination of 
every individual piece of wood to be used for a primary member in an 
airplane is out of the question. Neither is it necessary. The most 
reliable index of specific gravity, without making an actual test, is 
the ratio of spring wood to summer wood per annual ring. This is 
best seen on the cross or end section after it has been smoothed off 
with a sharp knife or a high-speed miter saw. In the softwoods the 
summer wood is the darker of the two bands composing each annual 
ring, as is shown in Figure 1, which illustrates cross sections from 
two wing beams of Douglas fir, one of average and the other of low 
specific gravity. In the ring-porous hardwoods (ash, for example) 
the summer wood appears more solid and very much less porous than 
the spring wood, but in the diffuse-porous hardwoods (such as 
birch) this is often very difficult to determine. For Douglas fir a 
minimum specific gravity of 0.47 has been established for high- 
stressed members, but this can probably be reduced to 0.45 with per- 
fect safety when used as a substitute for spruce. As a rule, wood of 
this species with less than 6 or more than 30 annual rings per inch, 
measured radially on the cross section, falls below the minimum 
specific gravity. The former usually comes from the center of the 
tree, where the wood is rapid growing and brash, while the latter is 
the slow- grown soft “ vellow fir” so characteristic of the outer layers 


DECAYS AND DISCOLORATIONS IN AIRPLANE WOODS. 7 


of very old trees. If each annual ring is composed of approximately 
one-third or more of summer wood the piece possesses the necessary 
strength. In those pieces with very narrow annual rings, in which 
_ the summer wood is indicated by a mere dark line at the outer edge 
of each annual ring, the wood is very soft and weak, often having a 
‘specific gravity as low as 0.34 (Fig. 1). i djs: 
Sometimes the proportion of material of low specific gravity in 
Douglas fir airplane lumber is exceedingly high. The writer has seen 
several consecutive carload lots of selected wing-beam stock at one 
factory in which from 25 to 50 per cent of the pieces in each car were 
below the minimum specific gravity. The stock was cut from old 


Fic. 1.—Cross sections of wing beams of Douglas fir of average and low specific gravity. 
The large proportion of summer wood, indicated by the dark bands, in the piece of good 
specific gravity (on the right) in comparison with that in the piece with low specific 
gravity (on the left) is plainly shown. : 


slow-grown trees, which yield the “ yellow fir” so much preferred by 
the trade, but which invariably contain a large percentage of material 
of low specific gravity not suitable for aircraft or any other type of 
construction where high strength is requisite. 

The same general relations hold good in Sitka spruce. Here, 
again, if the annual rings are too few or too many per inch, they in- 
dicate wood of low density. The minimum specific gravity for this 
species is established at 0.36. 

It is often difficult to approximate the specific gravity by visual 
examination of the proportion of summer wood per annual ring 
in the case of those pieces close to the minimum density permitted 
in softwoods. There is considerable chance for error even with 
Douglas fir, but with spruce this is increased, owing to the fact 


8 BULLETIN 1128, U. S. DEPARTMENT OF AGRICULTURE. 


that the summer wood and spring wood merge into each other, not 
being sharply delimited as in Douglas fir. With experience it 
is quite feasible to judge with accuracy the relative specific gravity 
of many of the pieces, leaving the doubtful ones for an actual test 
or to be worked up along with those below the minimum into parts 
less highly stressed. In making tests to determine the specific 
gravity it is not necessary to use the time-consuming immersion 
method. The pieces can be cut fairly regularly, oven dried, and the 
volume ascertained by measuring to the nearest half millimeter or 
to the nearest sixty-fourth of an inch. The weight should be ob- 
tained as usual. The writer has tested this method extensively and 
found the limit of error rarely over 0.01. In most cases the result 
will not vary from that obtained by the immersion method. This 
method can not be used on irregularly shaped pieces, however. 

In the ring-porous hardwoods, such as ash, it 1s very easy to 
determine the relative proportions of spring and summer wood in 
each annual ring. Here the condition is the reverse of that found 
in the softwoods. About three-fifths or more summer wood per 
annual ring in the case of white ash is necessary to give the 
strength required by the minimum specific gravity of 0.56. Wood 
with few annual rings to the inch in white ash has a high specific 
gravity, and this, as a rule, decreases as the number of rings per inch 
increases. Wood with 20 to 25 annual rings or more to the inch is 
usually worthless if strength is a requisite. The relations just dis- 
cussed are fairly constant throughout the ring-porous hardwoods, 
such as white oak, rock elm, and hickory. 

A large proportion of summer wood is not always an indica- 
tion of strength in white.ash. The notable exception to this rule 
is pumpkin ash, so called by the trade. This ash has remarkably 
broad bands of summer wood in the annual rings. These rings are 
often half an inch broad and contain only one or two narrow lines of 
pores in the spring wood, but the specific gravity of the wood is low, 
and when tested in static or impact bending it breaks with a brash, 
brittle failure under a light load. It can readily be detected by cut- 
ting with a knife, yielding softly without the resistance offered by 
good ash. When finished it has a waxy white, cream, or hght-brown 
color in tangential section and can be readily dented with any hard 
blunt instrument. In eross section the pores in the summer wood 
sometimes appear as small brown, rather indistinct spots. 

Pieces may be found with almost the same appearance as pumpkin 
ash which when tested with a knife prove to be hard and tough, 
with a good specific gravity; or, again, both hard and soft wood may 
be found in the same board. 

As nearly as can be ascertained from hearsay evidence, this pump- 
kin ash is not confined to a particular tree species, but may be found 
in any of the white-ash group when grown under swampy conditions 
in the southern part of the range. It does not necessarily occur, 
but when it does the central portion of the butt logs or even the entire 
trunk may be composed of such wood. Pumpkin ash has been as- 
signed by botanists as the common name for one definite tree species 
(Fraxinus profunda Bush), but the name as applied in the lumber 
trade denotes white-ash wood having the characteristics above de- 
scribed without regard to species. | 


7 
; 


DECAYS AND DISCOLORATIONS IN AIRPLANE WOODS. 9 


It is quite difficult to judge the specific gravity of diffuse porous 
hardwoods by visual examination except in those pieces patently 
very low or very high. Actual specific-gravity determinations will 
have to be used to a greater extent when handling this class of woods. 

In examining a piece of wood of any considerable length to deter- 
mine its specific gravity, care must be used to examine it throughout. 
Pieces in which the grain is not perfectly straight may have high 
specific gravity in one portion and a low density in another, as at- 
tested by the percentage of summer wood. This is due to the fact 
that trees may not develop wood of the same or nearly the same spe- 
cific gravity throughout their life. Such a condition is not at all 
uncommon in white-ash longerons, and it must be remembered that 


any given piece of wood is no stronger than its weakest portion. 


As a general rule, airplane timber should be purchased under speci- 
fications so worded in regard to the ratio of spring wood and summer 
wood per annual ring and number of annual rings per inch of radius 
as to reject at the source of supply most of the stock of low specific 
gravity. | 

COMPRESSION WOOD. 

Occasional pieces of wood of unusual growth are encountered. ‘The 
annual rings are very broad, with an abnormally large proportion 
of summer wood per annual ring, and there is little contrast between 
the spring wood and the summer wood. The specific gravity is very 
much higher than that of normal material. The abnormal growth is 
supposed to be due to the fact that the tree or portion of the tree 
from which the piece came had been under some long-continued un- 
usual stress or had been in an unusual position. The term “ com- 
pression wood” is usually applied to material of this nature. The 


writer remembers particularly a spruce wing beam with six annual 


rings per inch of radius, 75 per cent or more of summer wood per 
annual ring, and a specific gravity of 0.85. Since the usual specific 
gravity of spruce used is about 0.40, it can readily be seen that the 
weight of this wing beam was more than double the normal. Com- 
pression wood is not confined to spruce, but may be found in other 
soft woods. This type of wood is not desirable. Its strength proper- 
ties are uncertain, and its shrinkage does not correspond to that of 
normal wood, the longitudinal shrinkage being several times as great, 
while the radial and tangential shrinkage is very much less. The 
excessive weight is also a factor that must be considered in a deli- 
cately balanced machine. 


STEAMING AND BENDING. 


Wood may be rendered brittle or otherwise injured by steam bend- 


ing if this is not properly done. It is necessary to bend certain 


parts of an airplane frame in this way in order to obviate the ini- 
tial stresses which would result if these members were simply sprung 
into place. This should not be attempted on thoroughly air-dry or 
kiln-dry material, because wood once dried is weaker when brought 
back to a higher moisture content, and in addition such material has 
a tendency to spring back after the clamps are removed if it was 
not thoroughly resoaked. Asa rule, wood with less than 18 per cent 
of moisture based on oven-dry weight should not be steamed and 


- bent. 


9997—22——-2 


10 BULLETIN 1128, U. S. DEPARTMENT OF AGRICULTURE. 


‘Yoo high temperatures in the steam box will make wood brittle, 
seriously weakening it. Steaming should be accomplished at _atmos- 
_. pheric pressure and for a period not to exceed six hours. Higher 
pressure means higher temperatures and weakened wood. Most 


hardwoods are more or less discolored by this process, assuming a — 


dead-gray color, but this does not indicate injury. White oak may 
change to a blackish brown. White ash becomes a dead-gray color, 
on which a bluish gray discoloration may appear. Elm also takes 
on this gray shade to some extent. The change in color is very much 
less noticeable in the soft woods. 

Soft woods should not be steamed and bent, because they are very 
susceptible to injury by this process. When tested, the bent portion | 
will be very weak and brash. A close examination will reveal numer- 
ous slight compression failures on the inner curve of the bend. 
Spruce i is particularly subject to this type of injury. 


SEASONING, 


It is well established that a decrease in the moisture content of 
wood after the fiber saturation point is reached results in marked 
progressive increase in the strength of wood, accompanied by a de- 
cided shrinkage (63). ‘The fiber saturation point is the condition at 
which the cell walls are completely saturated, or, in other words, 
have absorbed the maximum percentage of water which they can 
hold, but the cell cavities are empty. For two reasons, then, to in- 
crease the strength and to prevent subsequent shrinkage when the 
pieces have been worked to size or even assembled, it is essential 
that airplane timber be dried or, as it is commonly termed, seasoned. 
This may be done by air drying, that is, natural seasoning in the 
air, or by kiln drying, that is, seasoning with artificial heat (4, 12, 
64, 65, 66,70). 

As a result of improper seasoning, particularly that which occurs 
unevenly or too rapidly, checks, which are small longitudinal splits, 
may occur in the wood. Almost invariably these are on the tangen- 
tial face, since wood as a rule shrinks about twice as much in the 
direction of the annual rings as it does radially or across them. The 
longitudinal shrinkage (with the grain) is so slight that it usually 
has no effect. Checks are decidedly weakening, but fortunately are 
easy to recognize. 

Airplane wood is usually kiln dried, because the seasoning process 
can be better controlled than in air drying; it is more rapid, a lower 
moisture content can be attained, and there is less tendency for kiln- 
dried wood to shrink and swell with subsequent changes in the humid- 
ity of the air. Extensive tests have been made on the effect of arti- 
ficial seasoning (73). Kiln drying when not properly done is a 
source of serious injury. Temperatures that are too high or proper 
temperatures that are combined with humidity that is too low may 


markedly weaken a charge of lumber, particularly if these conditions — 


are maintained for some time. The ‘detection of such injury, when 
not severe, is very difficult. Hence, it is highly important that self- 
recording instruments showing temperatures and relative humidities 
at all times be properly installed in the kilns and that these be cali- 
brated from time to time. In pronounced cases the lumber els 
readily reveal Its brittle nature when picked with a knife blade. 


DECAYS AND DISCOLORATIONS IN AIRPLANE WOODS. “o» 1oh 


In all cases where it can not be determined satisfactorily by other 
metheds, representative pieces should be selected for impact bending. 
This test above all others most readily reveals brittleness in wood. 
But the test must be made, or at least the results and breaks reviewed, 
by some one experienced in this method of testing and thoroughly 
conversant with the mechanical properties of wood. 


COMPRESSION FAILURES. 


Compression failures may be due to abnormal stresses on the stand- 
ing tree (from a wind of unusual velocity, for example), to shocks 
in felling the trees, or to injury during the process of manufacture. 
Figure 2 shows a compression failure, probably caused when the tree 
was felled, in a section from an unfinished wing beam of Sitka spruce. 
As an example of injury during the course of manufacture, it might 
be mentioned that when a large number of wing beams, improperly 
piled, are transported 
on a car or wagon the 
weight and jar some- 
times cause such fail- 
ures in beams near the 
bottom of the pile. 

The smaller com- 
pression failures are 
not easy to detect. 
They appear as small . 
whitish wrinkles or 
irregular lines across 
the face of the piece, 
at right angles to the 
grain. A hand mag- 


nifier is often neces- Fic. 2.—Section oon an ge nage wing penn, oe 
3 a compression failure in Sitka spruce which probably 
sary to bring out the occurred when the tree was felled. 


finer failures dis- 
tinctly. The more pronounced failures appear as rather rounded | 
ridges resulting from the “ buckling ” of the wood fibers under stress. 
Compression failures are quite detrimental to the strength of 
wood, particularly as regards bending strength and shock-resisting 
ability. Material showing compression failures must not be used 
in parts where strength is required. One visible small compression 
failure usually indicates the presence of others. 
- Members with a small cross section are sometimes subjected to a 
rough test which makes the wood appear to be brash. It is well 
known that beams when placed in static bending characteristically 
fail first in compression, that is, in the fibers between the center 
(neutral plane) and the top of the beam. Hence, when a spruce 
longeron, for example, is supported at both ends and a load applied 
‘in the center, slight and practically invisible compression failures 
may result. Such failures appear as tiny whitish lines or wrinkles 
on the surface of the wood. If the member is then turned over and 
_ the load again applied until failure occurs, the break will be sharp 
and straight across with no splintering, typical of a compression 
break. This test should not be applied to softwood longerons, par- 
ticularly spruce, since the resulting breaks will nearly always be 


19 BULLETIN 1128, U. S. DEPARTMENT OF AGRICULTURE. 


short and sharp and may be confused with breaks in brash wood. 
By turning the member over after the first weight is applied, the 
-compression side, already partially failed, becomes the tension side 
under the new load; and when the new compression side fails, the 
tension side, already fractured squarely across, fails with it. To 
test the resiliency of such members, apply the load on one side only, 
and do so with moderation. 


SHAKES. 


Shakes are long tangential cracks or separations in the wood fiber. 
They are the result of an actual rupture of the wood due to wind, 
felling stresses, or other causes and are exceedingly detrimental to 
strength. Old shakes which have occurred while the tree was still 
standing are often stained and readily visible to the naked eye. 
This is also true where lumber has been exposed to the weather and 
dirt has filtered into the cracks. But where they are neither dis- 
colored nor opened up the rupture is not so easily detected. 


PITCH POCKETS. 


Pitch seams or pockets are lens-shaped cavities or openings be- 
tween the annual rings. They contain resin or pitch either in solid 
or liquid form; hence the name. These defects result from injury 
to the living tree, but the cause of injury is as yet unknown. Pitch 
pockets may indicate more serious wounds. ‘They are very common 
in Douglas fir, but may be found in other resin-producing softwoods, 
including spruce. | 

While pitch pockets reduce the strength of wood, the reduction is 
not as serious as is generally supposed. General specifications re- 
garding the presence of these defects have been worked out for wing 
beams of spruce and Douglas fir (69, p. 21). 


WORM HOLES. 


Worm holes are caused by the larve of three main types of wood- 
boring insects. The powdery or granular matter, the excrement or 
frass of either the adults or the “ worms,” or larvee, with which these 
galleries or burrows are usually filled, need not be confounded with 
clecay, since there is no difficulty in separating the two defects. In 
decay the transition from the soft, spongy, or friable wood to the 
normal hard material is gradual, while in the worm holes, usually 
circular or somewhat flattened when seen in cross section, the line 
between the firm wood and the frass or finely excreted wood is very 
sharp. 


(1) Ambrosia beetles or “ pinworms.” The small adult beetle bores into the 
green saw log or green lumber and deposits its eggs. The larve hatching from 
these eggs extend other burrows at an angle from the parent galleries. Mois- 
ture is necessary for this type of insect. There may be a blackish discoloration 
extending around the galleries, particularly those in the sapwood. This is the 
result of the activity of a wood-staining fungus which does not cause decay in 
the wood and therefore need not be considered as weakening the material. 

(2) Borers. The adults of borers, as a rule, require bark under which to 
lay their eggs. The larve hatching from these eggs burrow under the bark 
through the sapwood and sometimes into the heartwood; the holes are often 
large. 

(3) Powder-post beetles. Powder-post beetles cause the most dangerous type 
of defect, and their presence may be detected by fine, powdery droppings com- 
ing from the wood. The eggs are laid either in the pores of the wood or under 
the bark, depending upon the type of insect causing powder post. 


DECAYS AND DISCOLORATIONS IN AIRPLANE WOODS. 13 


Worm holes not only weaken the wood, but the presence of the 
larvee of powder-post beetles in the wood may render it unsafe. 
Ambrosia beetles or borers already in the wood can be killed by the 


ordinary dry-kiln process, but certain types of powder-post beetles 


require higher temperatures. It is much simpler to prevent attack, 


and this can be done by slight modifications in business management. 


Full information on these and other insect defects can be obtained 
from the Bureau of Entomology, United States Department of 


Agriculture. 


CHARACTERISTICS OF SPECIES. 


Different woods have certain inherent qualities which must be 


= recognized. Douglas fir has a decided tendency to splinter. The 


~ 


separation usually occurs along the annual rings in the spring wood 


adjacent to the summer wood. It is quite probable that this char- 


acteristic can be accentuated by excessive steaming with high tem- 
peratures during kiln drying, since it has been shown (6/) that 


certain softwoods in which the spring wood is sharply differ- 


entiated from the summer wood, in which category Douglas fir 
belongs, have the spring wood weakened more easily than the sum- 
mer wood by prolonged boiling. On account of this tendency of 
Douglas fir to splinter, aside from other reasons, Sitka spruce and 
Port Orford cedar are more desirable. 

White elm can be readily steamed and bent, but it usually warps 
and twists badly in drying. Douglas fir is very subject to splitting 
when nailed, while basswood is one of the least troublesome species 
in this respect. Black ash is low in stiffness. Other examples might 


be cited, but these are sufficient to show that the failure of a wood to 


meet certain requirements may be unavoidable. 


FAULTY DESIGN AND ASSEMBLY. 


As an example of faulty design the following instance may be 
cited. In one of the types of combat planes constructed in the air- 


eraft factories of this country two horizontal bolts were placed 


directly through the neutral plane in each upper front longeron 
of Douglas fir. A fitting was hung on the head of these bolts and 
two opposed high-tension wires, pulling at right angles to the direc- 
tion of the grain in the longeron, were attached to the fitting. 


While the ship was subjected to shocks and jars which occur par- 


ticularly during landing, these wires were in very unequal and 
irregular tension, varying from loose to very tight, and the strain 
on the longeron was exactly the same as if a chisel blade had been 
inserted through the neutral plane and the handle was being jerked 
sharply up and down. On the test flight of the first ships built the 
longerons did the obvious thing; they split in both directions from 


’ the bolts for a distance of a few inches to 2 feet. The failure was 


promptly blamed on the wood, which was assumed to be either 
weakened by decay or faulty kiln drying, instead of on the faulty 
design, where it belonged. Such mistakes arise from the lack of 


knowledge of the mechanical properties of wood on the part of the 
designer. | 


Incorrect assembly also plays a part in the unjust condemnation 


_ of perfectly good wood. One of the most common occurrences was 
to have interplane struts of Douglas fir or spruce, especially the 


14 BULLETIN 1128, U. S. DEPARTMENT OF AGRICULTURE. 


latter, reported as being made from decayed or “dead” wood. This 
was characterized by the fact that the struts, after assembly, if 


struck sharply on the side near the middle, would “bow” and re-— | 
main in such position. If struck then on the opposite side the © 


“bow” might reverse, but the strut rarely straightened up. This 
condition results from such an excessive tightening of the drift 


and flying wires that the struts acting as posts between the wings 
are placed under such a heavy compression load — 


that they are just on the point of failure, hence the 
inability to straighten up after bowing. Needless 
to state, such a condition is dangerous. 


of a vertical fuselage strut due to severe tightening 
of the tension wires in the fuselage. This failure 


floor. 


the attention of the reader to defects that can re- 
ceive only passing mention or must be omitted 
entirely, so that, if interested, he can become con- 
versant with these through the references cited. 


COLOR COMPARISONS. 


still in the living tree. For the first few years after 
formation wood is white or nearly so, and finally 
when the sapwood is transformed to heartwood a 


Fre. 3: uead of a decided color change takes place in most woods, 
showing a - com while in some the change is negligible. In such 
pesca spruce. species as redwood (Sequoia sempervirens (Lam.) 


caused by an ex- Hndl.), incense cedar, Douglas-fir, juniper (Juni- 


cessive  tighten- 


ing of the ten- perus), white ash, true mahogany, and white oak ~ 


sion wires in the 


"fuselage: there is a decided contrast between the light-colored — 


sapwood and the dark heartwood, while in spruce, 
fir, western hemlock, and yellow buckeye (Aesculus octandra Marsh) 


the heartwood more nearly approaches the sapwood in-color, and in © 


some cases it is difficult to distinguish between the two. Color is not 
always uniform in the heartwood. It is necessary to be thoroughly 


acquainted with woods to be able to recognize normal color variations — 


at a glance. : 

Color should always be observed on a freshly cut surface and the 
surface (whether radial, tangential, or cross) recorded when making 
permanent observations. All woods change color on exposure to 
light and air (54), the most noticeable change occurring in the lighter 


colored woods, particularly of the conifers. The first change is a 


yellowing, then a graying, and finally in some conifers a decided 


browning. These color changes have no weakening effect on the me- 
chanical properties of wood, since the discolored portion is a very 


thin surface layer and microorganisms play no role in this change 


Iigure 3 shows a compression failure in the head 


occurred before the machine had left the factory — 


In the foregoing pages no attempt has been made — 
to specify all the defects in airplane timber aside 
from decays or discolorations, or to describe fully | 
those mentioned. The writer desires merely to call — 


Color is a natural characteristic of wood while — 


Pl de ae ee, 


DECAYS AND DISCOLORATIONS IN AIRPLANE WOODS. 15 


of color. Light is necessary. Ordinarily these color changes are 
deepened by direct sunlight, which has a greater influence on the 
color changes than diffused light. ; 

Green wood usually differs in color somewhat from air-dry mate- 


_ rial of the same species, even on a freshly cut surface. There is a 


tendency for the more delicate tints to be obscured by drying. A 
system of color standards is at present sadly needed in describing 
colors of wood (43). Furthermore, the condition of the wood, that 
is, whether green, partly air dry, or fully air dry, invariably should 
be given consideration. 

_ The heartwood of sugar-pine, eastern white-pine (Pinus strobus 
_ Linn.), and western white-pine lumber often becomes a pink, lght- 
red, or vinous-red color upon air drying. This color is not confined 
_ to the surface layer, but is usually uniform throughout. No reduc- 
tion in strength results. Wood of this kind is very pleasing to the 
eye, so it is often desired by pattern makers. This discoloration 
need not be confused with an incipient decay, since it is so uniform 
throughout. Furthermore, it terminates abruptly in a horizontal 
direction and does not shade off gradually into the normal light- 
brown or cream-colored wood. 

Color is considered an index of strength properties (14, p. 359-360) 
in certain cases. The French marine department distinguishes two 
classes of European oak (Quercus robur L.), inferior wood (bois 
maigre) and good wood (bois gras). The former, which is straw 
yellow in color on a fresh cut, is much more subject to atmospheric 
influences; that is, it shrinks, swells, warps, twists, and splits more 
readily than the latter, which is pale brown to red brown in color. 
This is taken into account in specifying in what part of the con- 
struction the two types of wood shall be used. The Danish-Prussian 

marine specifications distinguish three colors of green oak wood, 
whitish yellow, brownish yellow, and reddish yellow, all three fre- 
quently with a tinge of gray. The first color on drying becomes 
straw-colored or sand gray, the second greenish brown, and the third 
reddish yellow or a dirty or dusty yellow-brown. It is considered 
that the unseasoned or fresh wood with any brownish color is de- 
cidedly poor in quality. 
_ The foregoing seems to be somewhat contradictory. In the opin- 
ion of the writer, trusting to the vagaries of color is an exceedingly 
uncertain method by which to judge the.strength properties of wood 
‘within a species or group and has nothing to recommend it as com- 
pared to the reliable index of the ratio of summer wood to spring 
wood per annual ring, which is particularly easy to judge in ring- 
porous woods like oak. There is a widespread opinion in regard to 
southern bald cypress (Taxodium distichum (Linn.) Rich.) that the 
darker the heartwood the more durable it is, but in reality the color 
of the heartwood makes no difference. 

Most woods when dried after a prolonged immersion in water 
reveal a grayish, lusterless color, much like that caused by steaming 
(see p. 10). Oak changes to a blue-black or a gray-black color 
after such treatment. 

Wood becomes a dirty gray to gray-black color after long exposure 
to the elements. This is well illustrated by unpainted poles, fence 
rails, posts, and shingles. The color change is caused by a number 


16 BULLETIN 1128, U. S. DEPARTMENT OF AGRICULTURE. 


of factors (52), but most important is a chemical reaction in which 
iron plays an important part. Timber is not weakened by this discol- 
oration, since the action is confined to the surface. | 

In boards cut from red cedar (Juniperus virginiana Linn.) white 
streaks are frequently found mingling with the normal red heart- 
wood. Such streaks are the white sapwood, the mingling being due 
to the irregular outline of the stem to which the heartwood con- 
forms or to layers which never change to heartwood. 

In Sitka spruce the heartwood has a light reddish tinge, slightly 
distinguishing it from the sapwood. Some trees of Sitka spruce, 
however, have a pronounced reddish or brownish pink heartwood, 
which is quite uniform throughout. The color difference is striking 
in a planed board or timber containing both heartwood of this kind 
and characteristic white sapwood. The same phenomenon undoubt- 
edly occurs, in red and white spruce, where it would be even more 
noticeable, since the heartwood in these species is normally as light 
colored as the sapwood. This reddish heartwood is just as strong as 
wood of the usual color and can be safely utilized. The same condi- 
tion is reported as being quite common in the Himalayan spruce 
(Picea morinda Link) in India (16, 29). 

The brown heartwood of incense cedar (8, p. 22-24) and western 
red cedar often has a reddish to purplish tinge, varying in intensity 
even in the same piece, while in other trees it may be completely lack- 
ing. It is entirely without significance in relation to the strength 
of wood so affected. 

In certain softwoods color variations may be connected: with 


changes in the rate of growth. In the heartwood of Douglas fir, — 


which has a distinct reddish or orange-reddish hue, the reddish color 
may be strongly intensified in long regular bands. A careful exami- 
nation will show that this color change is confined to a definite group 
of annual rings, narrower than those on both sides or containing 
a greater proportion of summer wood. The brown heartwood of the 
cedars also varies in this way. The so-called “ yellow fir,’ from the 
slowly grown, exceedingly narrow ringed outer layers of the old 
coast Douglas firs, is another example. The origin of such variations 
can be readily recognized, since the color is confined to.a definite 
eroup of annual rings. 

Occasionally an apparent discoloration in heartwood may be due 
to the failure of the wood to change color uniformly during the 
transition from sapwood to heartwood. This has been noticed in 
white ash, Douglas fir, western red cedar, western larch (Larix oe- 
cidentalis Nutt.), and other woods. The sapwood of white ash is” 
white or straw colored, while the heartwood is grayish brown, some- 
‘times with a reddish tinge. Hence, when the condition above men- 
tioned is found, the grayish brown heartwood will contain sharply 
delimited straw-yellow areas of various sizes and shapes. The wood 
is not weakened. How to avoid confusing this condition with the 
initial stages of white-rot will be considered later. 


Discoloration may be caused by dirt or dust. Surfaced or sanded — 


white pine or sugar pine is sometimes found covered with tiny little 


grayish black streaks following the grain of the wood. A close ex- 


amination will show that this is due to deposition of dust in the 
numerous resin ducts. This is especially apparent against the almost 


DECAYS AND DISCOLORATIONS IN AIRPLANE WOODS. 17 


white wood of these species, whereas in darker woods the streaks 
would pass unnoticed. ‘ 

Burns or scorches in wood may occur from the use of high-speed 
saws if the saws are not set properly to provide sufficient clearance. 
Improperly set planing knives will produce the same effect. Usu- 
ally such burns, appearing on the face of the piece as dark-brown to 
blackish blotches, are very superficial and can be planed off. The 
injurious effect is negligible. Deep burns, extending through a piece 
one-eighth or even one-fourth of an inch in thickness are rarely 
encountered and are usually confined to particularly susceptible 
woods, such as the white pines. These may result when a high-speed 
sander stops suddenly. The wood is injured and can not be used 
for highly stressed parts. Burns usually occur in the remanufac- 
ture of dry lumber and not on green lumber in the mills. 


DISCOLORATIONS CAUSED BY WOUNDS. 


The term “wounds” as applied to trees includes not only those 
scars by which the bark is removed from living trees, exposing the 
sapwood or heartwood with the death of the cambium over the ex- 
posed surface, but also those injuries by which the cambium is 
temporarily damaged but not killed. The cambium, which is very 
susceptible to injury, is the very narrow layer of delicate growing 
- tissue of a tree situated at the junction of the living bark and sap- 
wood. When this tissue is injured or killed, a healing or callusing 
process immediately begins which causes a dip or wave in the grain. 
Consequently, irregularity of grain in a timber often indicates prox- 
imity to a wound. 

Wounds in living trees result from a variety of causes, among 
_ which may be mentioned fire, lightning, insects, birds, and man. 
All such injuries are usually accompanied by a discoloration of 
the wood, particularly the sapwood. Such discolorations are most 
intense in the hardwoods, especially in the sapwood of such species 
as white ash, hickory, maple, birch, and tulip poplar. 

When the wood of a living tree is exposed to the air it dries out 
and changes color. In softwoods the change is to a grayish brown 
or dead-gray color, while in hardwoods the change ranges from a 
deep brown to almost black, most noticeable in the sapwood. This 
color change is an oxidation process. Although the wood is not 
weakened by this change, wound wood of this type should be 
avoided, owing to the fact that during its exposure to the air it 
often becomes infected by wood-destroying fungi and may be weak- 
ened by incipient ‘decay. 


LIGHTNING WOUNDS. 


The general appearance of hightning injury is readily recognized. 
Spike tops and stag heads, together with the spiral wounds exist- 
ing for many feet along the trunks of the trees, are unmistakable. 

Besides such wounds, the cambium is very susceptible to electrical 
discharge and may be affected for some distance down the tree with- 
out any outward visible indications. This irritation to the cambium 
results in the formation of a layer of cells changed in both shape and 
structure from the normal. Often in the conifers an unusually large 

number of resin cells or resin ducts are formed within this injured 


9997—23——_3 


18 BULLETIN 1128, U. S. DEPARTMENT OF AGRICULTURE. 


portion. In ashort time the cell formation returns to normal. Ulti- 
mately, as the growth of the tree proceeds, these lightning rings, 
always following one definite annual ring, are deep within the wood, 
extending completely or partially around the circumference over a 
varying distance. When the tree is worked up for lumber certain of 
the boards may have such lightning rings extending completely 
through, both in width and length. Such a board then consists of 
two layers of wood held together by a zone of abnormal structure 
forming a plane of cleavage. Checking often occurs along this line, 
since the continuity of the medullary rays may be interrupted. Such 
checks are striking, since they invariably are tangential, following 
an annual ring on end section or radial face but not visible on the 
tangential face. This 
is not at all an un- 
common defect in air- 
plane timber. An ab- 
normal number of 
resin ducts may be 
found in the annual 
ring following many 
types of mechanical 
injury, but for prac- 
tical purposes there is 
no difference between 
such so-called trau- 
matic resin ducts and 
the abnormal ducts 
formed as a result of 
hghtning injury. 

It is self-evident 
that wood with these 
hghtning rings must 
be used with discre- 
tion. Eventhough 
the lightning ring 
does not check on dry- 
ing, when a mem- 
Fic. 4.—Section from a finished interplane strut, showing ber with this defect is 

a small lightning injury in Sitka spruce. put under severe 
strain and stress a 
serious check may develop. Of course, every member showing a 
lightning ring need not be considered valueless. Such a defect in 
the stream line of a strut, for example, would be trifling, while a 
much shorter ring in the butt or inner bay of a wing beam, particu- 
larly if in the same plane as the bolts, would be serious. ‘The same 
ring in the tip of such a beam could be overlooked. | 

The detection of lightning rings in rough lumber is exceedingly 
difficult, unless accompanied by small wounds, which is sometimes 
the case. Then such wounds must be scrutinized closely for the 
presence of a lightning ring. Two or more of these wounds, which 
resemble sapsucker wounds, occurring on the same annual ring 
and connected by a lightning ring, are sometimes found. Figure 4 
shows one of these wounds on an interplane strut, in this case not of 


ay 


ee ele ee ee eee 


FO Pes eS TR PM Eee 


DECAYS AND DISCOLORATIONS IN AIRPLANE WOODS. 19 


any importance, since the injury occurred alone with only a very 
short lightning ring and on the stream lining where high strength 
is not requisite. Lightning rings are more readily detected on a 
member before it is sanded. In some cases the seriousness of the 
defect can be determined after planing but before the piece is 
shaped. This is usually possible when the defect runs entirely 
through the piece. 

In white fir the lightning rings are easily detected both on cross 
section or on the radial face. The normal color of the summer wood 
is a light brown, while the lightning ring is a pronounced brown 
or purplish brown, which stands out strongly against the whitish 
sapwood or heartwood. Abundant resin ducts occur in these rings. 

Lightning rings in incense cedar are dark brown in color, standing 
out plainly in the white sapwood, but are not so apparent, although 
still recognizable, . 
against the reddish |Hije  ” 
brown heartwood. 
Resin ducts do not ac- 
company lightning 
rings in cedar. 

Sitka spruce wood 
is rather susceptible 
to the effects of elec- 
tricity. The light- 
ning rings appear as 
light to dark brown 
lines in the pale pink- 


ish heartwood or white ee rma eae ee eee premeoe pea 

: showing a lightning ring in Sitka spruce. e row oO 

sapwood. Rings are resin oles extending entirely Be section can be 

1 seen in the summer wood of the fifth annual ring from 

found which appear the bottom. The defect ran the entire length of the 
to be chiefly composed _ beam. 


-of resin ducts; in fact, 


when viewed on the end section, it is seen that the resin ducts are so 
numerous that they almost coalesce. This condition is illustrated in 
Figure 5. Furthermore, spruce wood is peculiarly susceptible to dis- 
coloration by lightning injury. Often in connection with a lightning 
ring a reddish brown discoloration is found, somewhat tinged with 
purple. This discoloration rarely extends radially more than 3 or 4 
inches from the lightning ring toward the pith, but may extend 2 feet 
beyond the limits of the ring in a vertical direction. Wood so dis- 
colored is not weakened. Furthermore, the color is not sufficiently 
intense to detract from its value for any purpose, particularly since 
the discoloration when varnished appears merely as a darker tone 
of the normal heartwood. 

The lightning rings found in Douglas fir are red-brown in color, 
darker than the summer wood and consequently are quite apparent 
in the white sapwood and orange-red or yellowish heartwood. These 
rings are practically composed of resin ducts. The ducts are smaller 
than in Sitka spruce. 

The reader must not get the impression from what has been written 
that lightning rings are a feature of every piece of wood, but the 
do occur and must be taken into account. 


20 BULLETIN 1128, U. S.. DEPARTMENT OF AGRICULTURE. 
SAPSUCKER WOUNDS. 


Sapsuckers are a group of woodpeckers which extract the sap 
from the inner bark and sapwood of living trees and eat the cambium. 
The final result after the wound has healed or callused over is the 
so-called bird pecks (15, 35). This injury is often accompanied by 
extensive staining, particularly in the hardwoods. On the ends of 
logs or boards the healed wounds appear as stained areas of varying 
size, each containing a more or less open, short, radia] check in con- 
nection with distorted grain. The general appearance is a T-shaped 
or triangular mark or check surrounded by a stain varying from 
brown to almost black. More than one usually occurs in the same 
annual ring. On the edge-grain or slash-grain faces of sawed lumber 
these injuries usually appear as small knots-or distortions in the 
grain, surrounded by more or less stain which is usually localized, - 

-but the stain may be accompanied by a bleaching which extends for 

some distance. ‘The stain is always adjacent to the distorted grain, 
and the more distorted the grain the greater 
the extent of the stain. 

The stain appears to be the most injurious 
of the two, but in reality the distorted grain 
is the only cause of weakening in the wood. 
The strength of the wood is not much affected, 
so that wood with bird pecks in most cases 
can be safely utilized. Figure 6 shows a sec- 
tion from a white-ash longeron with a minor 
injury of this kind which does not impair the 
usefulness of the member. Pieces are some- 
Fig. 6.—Section from a times unsuitable for handles, owing to the 

ing a sapsucker injury tendency of the grain to roughen up at these 

or, bird peck ‘in white - places when planed. If the. pecks are nu- 

Le merous in one annual ring it is best not to 

use the piece, for although it has not been determined by comparative 
tests it is quite probable that such material is reduced in strength. 
Checks or wind-shakes are very prone to occur along an annual ring 
containing numerous sapsucker wounds or even at individual in- 
juries. These often prove to be serious in thin veneer, since pieces of 
the distorted grain are likely to fall out. Sapsuckers are responsible 
for much of the curly grain and bird’s-eye found in ap poplar. 
Both stain and bird’s-eye in this species are shown in Figure 7. sel" 

Practically all tree species, both softwoods and hardwoods, are 
subject to this type of injury, but hard maple, soft maple (Acer sac- 
charinum Linn.), tulip poplar, and hickory in particular stain badly. 
The bird pecks are common ‘in white ash, but the accompanying 
stain is generally closely localized. 


PITH-RAY FLECKS. 


Pith-ray flecks, which are also termed medullary spots and pith 
flecks, are caused by the larve or grubs of certain insects living in 
the cambium of living trees during the growing season (10, 17, 20, 
21, 44, 67). These insects comprise several species of the genus 
Agromyza belonging to the order Diptera. On the end section of 
logs or lumber the flecks appear as small brown crescent or half-moon 


DECAYS AND DISCOLORATIONS IN AIRPLANE WOODS. 21 


shaped areas, which on the tangential or slash-grain face and the 
radial or edge-grain face of a board appear as brown streaks, usually 
running in a vertical direction. (Figs. 8 and 9.) The wood for a 
little distance around a pith-ray fleck may be darker than normai. 
This is particularly so in poplars or cottonwoods (Populus spp.). 
On the whole, the injuries are not at all serious, having no noticeable 
effect on the strength of the wood unless the flecks are exceedingly 


Fie. 7.—Slash-grain or tangential surface of a tulip- poplar board, showing stain and 
bird’s-eye caused by sapsuckers. One-third natural size. (Courtesy of. ther Uz ss. 
Biological Survey.) 


numerous. Only in the cherries (Prunus spp.) may a weakening 
be expected, a there the affected wood tissues are broken down, 
while in the other woods they are but little distorted. Furthermore, 
the presence of pith-ray flecks is usually hard to detect in the heart- 
wood of cherries. The color of the heartwood differs but little from 
the color of the pith-ray flecks. 

Pith-ray flecks are found in all the common poplars or cotton- 
woods, birches, m aples, cherries, basswood, and many others, but 
there is considerable variation in their abundance on different closely 
related species. For example, these flecks are very common in soft 
maple, while they are rather infrequent in hard maple. In river, 
gray, and paper birch (Betula nigra Linn., B. populifolia Marsh, 
and B. papyrifera Marsh) they are found in abundance, but are 


22 BULLETIN 1128, U. S. DEPARTMENT OF AGRICULTURE. 


somewhat uncommon in yellow birch, although the writer has found 
them from time to time in propeller stock of this species. Softwoods 


Fig. 9.—Tangential section of the trunk of a tree of silver maple, showing pith-ray flecks. 
Natural size. 


DECAYS AND DISCOLORATIONS IN AIRPLANE WOODS. 23 


are not subject to these pith-ray flecks, but a somewhat similar injury 
in western hemlock known as black check results from the work of 
a different insect (77). | 


CHEMICAL DISCOLORATIONS. 


The sapwood of many species of wood is subject to discolorations, 
varying widely in appearance but fundamentally the same, which are 
the result of chemical action (2). Sapwood is rich in organic com- 
pounds and also contains certain soluble ferments which facilitate 
the oxidation of such compounds. Under favorable temperature con- 
ditions, for example, when green sapwood is exposed to the oxygen 
of the air, these ferments, known as oxidizing enzyms, act on the 
organic compounds in the sapwood. The result of their action, which 
is an oxidation process, is a discoloration of the sapwood, with the 
colored substance most noticeable upon microscopic examination in 
oe cells mainly concerned in the storage and transportation of 

ood. ) 

Hot, humid weather is most favorable for this staining. Cool, dry 
weather retards it or prevents it entirely. Logs immersed in water 
are not affected. Light is not necessary for this reaction, as it takes 
place just as readily in darkness. The stain is confined to the 1m- 
mediate surface layer, and the wood is not weakened. The most 
practical method of prevention, if this is considered necessary, is by 
dipping the green sap boards into boiling water for a few minutes 
as they come from the saw. 


HARDWOODS. 


Birch, maple, and cherry stain a reddish yellow or rusty color. 
The wood of alder becomes very intensely red or red-brown on freshly © 
cut surfaces, often within an hour or so after the surface is exposed 
(40). In the case of red alder (Alnus oregona Nutt.), if the wood 
dries and remains white, the red color will appear upon the addition 
of water in the presence of air, provided the temperature is favor- 
able. A bluish stain often occurs in red gum (Liquidamber styraci- 
flua Linn.). 

The European linden (7%ia europaea, Linn.) is subject to a strik- 
ing discoloration (39), which probably also occurs on basswood 
in this country. When freshly sawed boards are so closely piled 
that they dry slowly, a more or less apparent dirty green color ap- 
pears in from 8 to 10 days. Under very favorable conditions the 
color is exceedingly bright and intense. The color varies between 
wide limits, from yellow-green or brown-green through all possible 
gradations to the purest moss green. Only the outer layers of the 
wood are colored. Usually the stain extends to a depth of one 
thirty-second of an inch or rarely to a depth of one-eighth of an inch. 
The staining, although it is the result of a chemical reaction (an iron- 
tannin reaction), is not dependent on temperature, since it occurs 
just as readily in ee asin summer. Too much moisture hinders 
the reaction, but a certain degree of moisture is essential. If the 
boards are dried quickly no staining results. 


SOFTWOODS. 


Coniferous woods are not so commonly subject to this type of dis- 
coloration, but there are a few examples. The ends of incense-cedar 


24 BULLETIN 1128, U. S. DEPARTMENT OF AGRICULTURE. 


logs sometimes have a decided brownish red stain on the sapwood. 
This is of no importance, because it does not occur on sawed lumber — 
except so faintly as to be almost invisible. ) 

A very unsightly discoloration known as brown-stain (43, p. 
305-307), which, however, does not weaken the wood, often occurs 
on sugar pine, but is frequently not noticeable until the lumber has 
been finished. ‘This appears in the sapwood as a streaky, dirty, light 
to dark brown or brownish black discoloration, and may be super- 
ficial or very deep. It is quite striking against the faint yellowish 
white sapwood in finished lumber. The discoloration occurs on 
green sap lumber upon exposure to the air and may appear during 
air drying or kiln drying.. In the last instance it is known as kiln 
burn, but it does not differ from the brown-stain and is probably 
sometimes due to defective circulation in the kiln. Brown-stain is 
particularly bad in lumber cut in early spring. Hot, humid weather 
and poor circulation of air in the lumber piles favor the staining, 
while cool, dry weather and proper piling tend to prevent it. This 
brown stain is an oxidation process similar to the others, but whether 
it can be prevented by the hot-water treatment is doubtful, since the 
discoloration often extends deeply into the lumber. | 

The wood of sugar pine in dead trees, standing or down, may be 
affected by a very brilliant orange stain which occurs in spots or as 
a solid color, but more often is seen as narrow to broad streaks 
parallel to the grain of the wood. It is found in both heartwood 
and sapwood. ‘The exact cause of this discoloration is unknown, but 
it is probably the result of chemical reaction, since no fungous 
mycelium has been found associated with it. While the wood is 
apparently not weakened, the presence of this stain indicates that 

the lumber came from dead trees, and it should be closely watched 
' for signs of decay and insect borings. 


DISCOLORATIONS CAUSED BY FUNGI. 


From an economic standpoint by far the most important discolora- 
tions in wood are caused by fungi. Fungi are very simple plants 
which can not live on the simple food elements of the soil and air 
and build up complex organic matter, as is done by the green plants | 
with which we are familiar, but must have organic matter already 
prepared in order to sustain life. This they find in the material 
built up by green plants; hence they may attack living plants, or 
dead portions of such plants, or any dead vegetable matter. Some 
live on animal matter, but these do not concern us. The develop- 
ment of fungi is dependent upon a supply of oxygen, of which there 
is always sufficient in the air, a certain degree of moisture, a suit- 
able range of temperature, and the necessary food substances. ‘The 
maximum and minimum of these requirements vary widely with 
different fungi. Bee! 

The fungous plant consists of very fine threads (hyphe), which 
are invisible to the naked eye unless they occur in mass. Individual 
hyphe require magnification by a compound microscope. Collec- 
tively, the hyphe are termed mycelium. The hyphe usually live in 
the tissues of the substance on which the fungus is growing. The 
fruiting bodies or sporophores, which vary in size from those so small 
as to be invisible to the naked eye except in a mass to others quite 


DECAYS AND DISCOLORATIONS IN AIRPLANE WOODS. 5 


large and conspicuous, appear on the surface after the hyphe have 
developed vigorously. The fruiting bodies bear the spores, which 
are microscopically small reproductive bodies of relatively simple 
structure. The spores, being very lhght, are borne about by air 
currents. If they alight in a ‘suitable place under proper conditions, 
germination takes place and hyphe develop. 

Fungi growing on wood may be roughly divided into two groups, 
depending on the habit. of growth of hyphx. In the first group are 
placed those fungi whose hyphe live on the substances contained in 
the various cells of the wood, while to the second group belong those 
whose hyphe attack the actual wood substance of the cell walls and 


_ destroy it. The first group 1s principally represented by the sap- 


staining or discoloring fungi, so called because they produce various 
discolorations which are confined to the sapwood. To the second 
group belong the wood-destroying fungi. 


SAP-STAIN. 


DESCRIPTION. 


Sap-stain, which has been extensively studied (23, 27, 38, 50, 61), 
even though it may render wood very unsightly does not dee 
its strength for practical purposes. The discoloration is normally 
limited to the green sapwood, because as a rule there is neither 
_ sufficient food material nor moisture in the dry dead heartwood for 
the development of the fungus. The discoloration is usually most 
intense in the medullary rays, since in these tissues the bulk of the 
food material is found. The stain is produced in two ways, either 
by a reflection of the color of the hyphz through the cell walls of the 
wood or by an actual color solution excreted by the hyphx, which 
stains the wood itself. These stains vary in color from blue or 
blackish to reddish, the former being the most common. Since these 
fungi do not attack the cell walls in which the strength of the 
wood reposes, except to a negligible extent, discolored wood is not 
appreciably weakened. This has been determined by comparative 
oe tests on stained and unstained wood (4/,; 56, p. 13-14; 

17). 

ee the strength of the wood fibers is not impaired by such 
stains, the wood is objectionable in places where color is a factor. 
Tn a ‘highly varnished interplane strut, for example, a stained 
streak is unpleasant to the eye. F urthermore, it may lead to a 
strong prejudice against the airplane having such a member, be- 
cause while by the uninitiated a dangerous defect not readily ap- 
parent is passed unnoticed, an unsightly though harmless discolora- 
tion is considered to indicate a serious weakness. Where the dis- 
coloration is to be covered up or painted there is no reason to ex- 
clude it. 

It must be remembered that the conditions which promote the 
development. of the fungus discoloration are highly favorable to 
_ the development of true wood-destroying fungi. These conditions 
_ are a comparatively high humidity and warm weather. Sap-stain 
is at its worst during warm wet weather, when the humidity of the 
_ air is relatively high and lumber dries slowly. It is at such periods 
that the most severe staining may occur if the lumber is not properly 
handled. The climate of the Pacific Northwest is usually exceed- 


yo0(—20o-—4 


26 BULLETIN 1128, U. S. DEPARTMENT OF AGRICULTURE. 


ingly favorable for the development of wood-staining and wood- 
destroying fungi during the spring and summer months. It is from 
this region that the three most important airplane woods—Sitka 
spruce, Douglas fir, and Port Orford cedar—are obtained. 

Wood containing very severe sap-stain therefore should be care- 
fully examined for the presence of wood-destroying fungi. If de- 
cayed, the wood will be brash and may be softer and less tough 
when the fibers are picked with a knife. If any doubt exists after 
an inspection, the decision should be based on a microscopical ex- 
amination or a mechanical test by a qualified expert. 

The most important of these stains from an economic standpoint 
is blue-stain, caused by various species of Ceratostomella, which may 
be found on almost any hardwood or softwood. Softwoods are 
more commonly affected, and certain species are particularly sus- . 
ceptible. This is due both to the character of the wood and to the 
climatic conditions of the region where the species occurs. The 
discoloration may be more or less superficial, occurring as spots or 
streaks. If the staining is severe, however, the entire sapwood will 
be affected, so that it can not be surfaced off. The fungi causing 
these stains are not readily seen, but sometimes if a deeply stained, 
almost black piece is inspected with a hand magnifying glass, in- 
numerable bristles with a bulbous base will be observed. ‘These are 
the fruiting bodies, containing an enormous number of spores, which 
are exuded and are carried about by air currents. Falling on green 
sap lumber they sprout, the hyphe develop, and more blue-stain re- 
sults. Under favorable conditions blue-stain may develop with sur- 
prising rapidity, appearing on lumber within a day after sawing. 

Other colors, such as black, brown, gray, red, pink, and violet, are 
caused by species of Hormodendron, Hormiscium, Graphium, Pen- 
icillium, and Fusarium. These discolorations are not nearly so 
common as blue-stain. 

Certain other discolorations of sapwood are produced by fungi be- 
longing to the molds, of which the green mold on fruits or in certain 
cheeses is an example. Usually such stains are superficial and 
readily surface off. They occur on both hardwoods and softwoods. 
The bluish or blackish stains are difficult to separate by visual inspec- 
tion from the true blue-stain. 


CONTROL. 


Considerable study has been devoted to the development of methods 
of prevention and control of sap stains caused by fungi (J, 25, 72). 
Naturally most of this work has been concentrated on blue-stain, 
and the following paragraphs are most directly applicable to it, but. 
will probably also apply fairly well to the others. Blue-stain may 
be checked after it has started, but the stain can not be eradicated 
unless it is so superficial that it can be planed off. Therefore, the 
keynote of all treatments must be prevention. | 

Unfortunately, there is no one principle that. can be applied to the 
prevention of this discoloration. Staining may take place at any 
time after the trees are felled or, in the case of dead timber, while 
they are still standing. Hence, in logging operations in regions 
where blue-stain is of importance, the logs should be removed from 
the woods as soon as possible after the trees are felled and bucked 


) 


sO ee” 


—_—.:chU6- hl 


SO a er tena | 


ee ee ee eee a ae 
‘ 


DECAYS AND DISCOLORATIONS IN AIRPLANE WOODS. OT 


(cut up into log lengths). The practice of leaving logs lying in the 


woods for months can not be too strongly condemned, as this not only 
-causes blue-stain but also promotes the growth of wood-destroying 


fungi. Furthermore, the inevitable attacks of wood-boring insects 
assist greatly in the spread of blue-stain and decay. When the trees 


are bucked the narrow space left by the saw kerf between the logs as 
they are lying end to end affords an ideal situation for the develop- 
ment of the blue-stain fungi. Such logs often stain deeply, while 
those with the ends fully exposed remain entirely free from discolora- 
tion. As soon as the logs are in the mill pond danger from staining 


is over for the time being, since the oxygen supply is so reduced that 


the fungi can not develop. 


The greatest danger of all is encountered during the process of 


_ drying the rough lumber as it comes from the saw. The best method 
of preventing blue-stain is by kiln drying. If the stock checks easily, 
so that low temperature and high humidities must be maintained 


over a considerable period, some of the other staining fungi such 
as molds, may develop. But these can be checked by raising the tem- 
perature in the kiln to about 160° F. or slightly more for an hour 
by turning live steam into the kiln. When this is done, care must be 
taken to keep the air saturated while steaming and to reduce the 


humidity gradually after steaming. When the stock has once been 


dried properly the moisture content has been so reduced that there 


is no more danger from staining, provided it is kept dry. A dispute 


that arose over the efficiency of a dry kiln was immediately settled 
by the fact that the blue-stain fungi had resumed vigorous growth 
the day after the stock was removed from the kiln. This could not 
have occurred if the lumber had been properly dried. 

All airplane lumber should be kiln-dried immediately, since this 
not only prevents blue-stain, but also stops the growth of wood-de- 
stroying fungi, prevents future checking, and greatly reduces weight 
without in any way injuring the lumber, provided temperatures that 
are too high are avoided. 

In case kiln drying is impossible, treatment with antiseptic solu- 
tions is of considerable value. As it comes from the saws the green 
lumber is dipped into a hot or cold chemical solution. The solutions 
most commonly employed are sodium carbonate or sodium bicar- 
bonate in water. Neither is 100 per cent effective under optimum 
conditions for staining, but they aid materially in checking discolora- 
tion. These two chemicals, however, color the treated wood a 
decided yellow or brownish. Sodium fluorid, although it does not 
stain the lumber and is slightly better for blue-stain, is not so effec- 
tive against certain molds as the two solutions first mentioned. This 
chemical is seldom used. It must be remembered that the strength 
of the solutions must necessarily vary with the conditions. The more 
favorable the conditions for blue-stain, the stronger the solutions 
should be. 

After being dipped in any of these solutions the lumber must be 
carefully open piled, that is, with spaces between the boards to insure 
good ventilation. Narrow cross strips or “stickers” chemically 
treated should be used, to prevent staining at the points where the 
boards and cross strips meet. Detailed instructions as to the proper 
methods of piling lumber may be consulted elsewhere (4, p. 17-21). 


28 BULLETIN 1128, U. S. DEPARTMENT OF AGRICULTURE. 


Salt is of little or no value in preventing blue-stain in comparison 
with the other chemicals. The application of salt after blue-staining 
has well started is almost a waste of money. In fact, the application 
of wet salt or a strong salt solution may prove detrimental in the long 
run, for if the lumber is dried after such treatment the affinity of 
the salt for water may cause the moisture content to remain much 
higher than normal. 

Mercurie chlorid in a 0.1 per cent solution is exceedingly effective — 
against blue-stain, but on account of its highly poisonous nature — 
and extremely corrosive action when in contact with many metals 
it is little used. , ) | 

Shipping green stock closely piled in closed box cars during the 
spring and summer months is almost certain to result in severe stain- 
ing. Indeed, the writer has seen some stock handled in this way 
which stained even in winter. On the other hand, any measures 
taken to prevent staining, such as open piling in gondolas or on 
flat cars, will almost certainly result in severe checking. Of the two 
evils, checking is by far the most serious in airplane stock, since 
checked lumber is greatly reduced in strength, while the stained 
lumber is only somewhat unsightly. Shipping green lumber in the 
close hold of a vessel, particularly if tropical seas are to be traversed, 
is an invitation to swift and sure disaster as far as sap staining is 
concerned. It is doubtful whether dipping in any chemical solu- 
tion now used, except possibly mercuric chlorid, would be effective 
under such severe conditions. | 

But, to repeat, the most effective measure to employ against blue- 
stain is speed in drying the wood. Get the logs from the woods to 
the saw with the greatest rapidity and the lumber from the saw di- 
rectly into the dry kiln. 


SAP-STATN ON SOFTWOODS. 


Certain species are peculiarly susceptible to sap-stain. This is 
due both to the character of the wood and to the climatic conditions 
of the region where the species grows. Western white pine, spruce, 
and southern yellow pine, the last-named wood including longleaf 
pine (Pinus palustris Mill.), shortleaf pine (P. echinata Mill.), and 
loblolly pine (P. taeda Linn.), are very subject to sap-stain, especially 
blue-stain, while true fir and cedar are not so easily affected. Douglas 
fir occupies an intermediate position. 

Besides blue-stain, a red stain has been very commonly found on. 
Sitka spruce airplane lumber. It occurred abundantly in the East 
on stock in cars just arrived from the Pacific coast and also developed 
on material along the Atlantic coast which had arrived unstained 
at the port of embarkation but was held over awaiting shipment. - 
The stain appeared as terra-cotta or brick-red spots on the rough — 
lumber, varying from very faint to a pronounced color. In the stock 
worked up in the factories in this country it was found that the 
stain was superficial, usually surfacing out during remanufacture; 
but reports from abroad indicate that the fungus developed very 
intensively by the time the lumber reached European ports, and the 
discoloration penetrated deeply into the sapwood, The appearance 
of the wood is not. marred to the same extent that it is by blue- 


DECAYS AND DISCOLORATIONS IN AIRPLANE WOODS. 29 


stain, and as far as is known no reduction in strength results. The 
fungus causing the discoloration is as yet unknown. 

Blue-stain is very severe on the white pines and is particularly 
noticeable because of their white wood. Plate I, left part, shows a 
section from a sugar-pine rib web in which the sapwood is stained 
to some extent. The small, darker, bluish black spots are the ends 
of the medullary rays, in which, as before stated, the fungous myce- 


lium is most abundant. The longer streaks are the resin ducts. 


Certain fungi (Penicillium spp.), stain the sapwood of the pines 
an orange-red to a crimson-red color. Another fungus (/usariwm 
roseum Link) is responsible for a pink to lilac color in the same 
woods. The color is produced by means of a pigment secreted by 
the hyphee, which actually dyes the wood. 

A wood-staining fungus (Zythia resinae (Fr.) Karst.) has been 
reported in Europe (9) as working on finished pine lumber after 
the wood has been oiled. The discoloration was characterized by 
violet to dirty red or even dark grayish brown flecks beneath the 
oiled surface of the wood. The spots were covered with minute 
pustules varying from violet, orange, and brown to black. These 
constitute the spore-producing bodies. ‘The discolored areas ex- 
tend within the wood as streaks closely associated with the medul- 
lary rays and resin ducts. The report does not state whether the 
discoloration was confined to sapwood. Apparently the wood was 
not reduced in strength. As far as is known, this stain has not yet 
been found in the United States. 


SAP-STAIN ON HARDWOODS. 


Hardwoods are not as subject to the stains caused by fungi as are 
softwoods. In hardwoods, when sap-stain does occur, the discolora- 
tion is most intense in the medullary rays and large pores or vessels. 
In a wood such as yellow birch, in which these vessels are not too 
closely crowded, the stain, if not too severe, appears in longitudinal 
section aS very narrow bluish black lines or streaks following the 
erain of the wood. This stain will not necessarily be confined to the 
surface layers, but may extend entirely through the sapwood. Of all 
the hardwoods, however, red gum seems to be the most susceptible 


. to stains caused by fungi. 


BROWN-OAK DISCOLORATIONS. 


A somewhat different discoloration than those previously de- 
scribed, in that it is confined to heartwood only, is the “ brown oak” 
(18, 19) found in Great Britain. This is also known as “red oak” . 
and “ foxiness,” but the name first given is most commonly accepted. 
Instead of the normal heartwood, certain trees of the common Euro- 
pean oak have a dull-brown to rusty brown or even rust color in the 
heartwood. In some cases the color is uniform, while again longi- 
tudinal streaks of normal-colored heartwood may alternate with 
those of the brown color. When these brown streaks contain black 
patches this type of wood is known as “tortoise-shell” oak. This 
discoloration originates in the heartwood of living trees, the normal 
heartwood changing first to a faint yellow color, which continues to 
deepen until the brown stage is attained. The color change is caused 


by a fungus, but so far as known the infected wood is not weakened. 


30 BULLETIN 1128, U. S. DEPARTMENT OF AGRICULTURE. 


The hyphe attack the cell walls very slightly, presumably living on 
the tannin, of which oak wood contains a high percentage. The 
value of the wocd for veneers is very much enhanced. The writer 
has no record of this discoloration being found on oaks in this 


country. 
DECAY DISCOLORATIONS. 


The hyphe of wood-destroying fungi living within the wood feed 
on the various substances composing the cell walls. They use certain 
constituents of the cell walls, neglecting others, with the result that 
these walls are broken down, the wood being thus greatly weakened 
and more or less destroyed. It is the breaking down of the wood and 
the change in its physical and chemical qualities that is termed decay. 
The degree of decay is determined by the energy of growth of the 
fungus, the length of time it has been at work, and the type of wood 
it attacks. Some fungi attack many different kinds of wood, while 
others are limited in their choice. Owing to their less exacting moist- 
ure requirements, wood-destroying fungi are able to live on heartwood 
as well as sapwood. The fruiting bodies, usually quite large, are 
found on the surface in the form of brackets, crusts, or mushrooms 
or toadstools. They are not developed until the hyphe have been 
at work for some time; consequently, the presence of fruiting bodies 
indicates serious decay. 

Two types of wood-destroying fungi may be recognized, (1) those 
mainly attacking the heartwood, rarely the sapwood, of standing 
living trees, and (2) those principally confining their activities to 
the manufactured product, such as sawed lumber, crossties, and 
poles. The former type may continue their work of destruction after 
the tree has been cut down and worked up into lumber. The latter, — 
attacking the manufactured product, usually invade the sapwood 
first, since it is far richer in stored food, generally has a higher 
moisture content than the heartwood, and is not so inherently re- 
sistant to decay. Fungi causing this type of decay are often very 
abundant in yards where the lumber is closely piled on damp earth, 


with little or no aeration under the piles, and much accumulated 


wood débris scattered throughout the yard. Unfortunately, such 
conditions are all too prevalent in mill yards. Sanitary yards both 
at the mills and the factories are badly needed. Humphrey (28) | 
gives a complete account of the life history and habits of these fungi, 
the damage caused by them, and methods for their control. 


CONDITIONS AFFECTING DECAY. 


All conditions which favor sap stains are equally favorable to 
wood-destroying fungi. Furthermore, the latter can attack wood 
with a lower moisture content, so the fact that wood does not sap- 
stain is no indication that fungi causing decay may not be present. 
The discolorations caused by the latter in sapwood are not so pro- 
nounced as sap-stain; consequently, they are much harder to detect. 

Moisture in wood.—Dry lumber will not decay. The most efficient 
method to prevent decay is to air-dry or kiln-dry lumber immediately 
and then keep it dry by proper methods of storage. Placing dry 
lumber in the open, exposed to rain, or in damp sheds can not be too 
strongly condemned. If the lumber becomes moist again, it is just 


DECAYS AND DISCOLORATIONS IN AIRPLANE WOODS. ol 


as liable to decay as before. To be sure, kiln drying is much better 
than air drying, since the high temperatures employed in the former 
process are probably fatal to the hyphe of some decay-producing 
fungi, while under the latter conditions the fungi may merely re- 
main dormant until suitable moisture conditions are again restored. 
However, since wood-destroying fungi are common around and in 
ards and wood-working factories, the chances are that kiln-dried 
peer will be reinfected, and if it becomes moist again decay will 
egin. 
hipping green or even partially air-dried lumber on long voy- 
ages through tropical seas in the hold of a vessel offers a chance 
for a heavy loss through decay. The close humid air of the ship’s 
hold becomes a perfect forcing chamber for wood-destroying fungi 
when warm latitudes are reached. Shipments of Douglas fir leav- 
ing the Pacific coast perfectly sound have contained a considerable 
percentage of decayed lumber when unloaded at a South African 
port (36, p. 36). Indirect reports indicate that the same condition 
resulted during the World War in some shipments of Sitka spruce 
ped to Europe through the Panama Canal and the Mediterranean 
ea. ) 

Durability of wood.—Resistance to decay, or as it is termed 
“durability,” is a factor that should no longer be neglected in 
selecting woods for airplane construction. Airplanes are being 
more and more exposed to unfavorable weather conditions as their 
use extends, conditions which in some instances are highly favorable 
to decay. Furthermore, certain conditions created by the construc- 
tion of an airplane promote decay. For example, in the interior of 
the wings the relative humidity may be much higher than that of 
the surrounding air, and there is often considerable condensation 
of moisture. In addition, the temperature is slightly higher. All 
rea factors are favorable to the development of wood-destroying 

ngi. 

Within’ any species durability increases with the increase in 
specific gravity. Consequently, the fact that only wood with high 
specific gravity is used for aircraft not only increases strength but 
serves to increase durability. However, it is well known that differ- 
ent species vary widely in their durability. Unfortunately, spruce 
is not at all durable. Neither are basswood and birch. Douglas fir 
is fairly durable, as is also white oak. But the cedars are remarkable 
for their inherent durability, and among these Port Orford cedar 
compares favorably with spruce in all its strength properties and is 
only slightly heavier. Consequently, this wood can not be too 
highly recommended for use in aircraft where resistance to decay 
must be considered. Sapwood must not be used under such cir- 
cumstances, for no matter what the species is it decays easily. 

Contrary to existing belief, the resin content of wood is of slight 
importance in relation to durability (74, p. 153-154; 75, p. 66-68). 
Resin itself has no poisonous effect, on the growth of fungous 
_ hyphe, and its only beneficial effect in increasing durability is its 
waterproofing action on wood. This is so slight, however, if the 
normal resin content of softwoods is considered, as to be practically 
negligible. If wood is rendered more durable through a sufficient 
increase in its resin content to have a decided waterproofing effect, 


32 BULLETIN 1128, U. S. DEPARTMENT OF AGRICULTURE. 


it is usually completely resin soaked or contains pitch streaks which ~ 
make it unsuitable for painting or contact with fabric coverings. 


INCIPIENT DECAY. 


It is a simple matter to recognize well-advanced rot or typical 


decay. Here the changes in the wood structure due to the longer ~ 


action of the wood-destroying fungus are so profound as to be very 
plainly apparent, but the earlier stages of decay, termed incipient 
decay, immature decay, or advance rot, are often far from easy to 
detect (6,7). In some cases detection is practically impossible with- 
out a microscopical examination of the wood. 

Specific gravity is not a reliable index of decay. It has been sug- 
gested that decay in any piece of wood will be immediately reflected 
in a lowering of the specific gravity. But this can not be detected 
unless the specific gravity of the piece was known before decay com- 
menced, a manifest impossibility in most cases. Incipient decay does 
not cause a sufficient reduction in the specific gravity to bring the 
heavier pieces of wood below the minimum set for the species. The 
writer has tested pieces of yellow birch, white ash, and Douglas fir 
with conspicuous incipient decay and found the specific gravity of the 
affected pieces to be from 0.05 to 0.2 higher than the minimum per- 
missible. The same condition will exist in all species. Douglas fir 
with pronounced white cellulose pockets characteristic of the final 
stage of red-rot or conk-rot has been found in some cases to have a 
higher specific gravity than the minimum of 0.45. Of course, when 
sound such wood had a high specific gravity. 7 | 

Wood is weakened by incipient decay, the degree depending on the 
stage of the decay and somewhat on the species of fungus at work. 
Furthermore, if infected material is merely air dried the hyphxe may 
remain dormant, ready to continue their work of destruction again 
if suitable conditions arise. The chalky quinine fungus (/omes 
laricis (Jacq.) Murr.), which normally causes decay in the heartwood 
of various coniferous trees, either living or dead, has been found 
causing decay in the roof timbers of cotton weave sheds (4). Un- 
doubtedly this originated from timbers containing incipient decay 
of this species placed in the roofs at the time they were built, where 


the high temperature and humidity which prevails in such sheds soon 


resulted in renewed activity of the fungous hyphe and their spread 
to adjoining sound timbers. The rose-colored Fomes (Yomes roseus 
(Alb. and Schw.) Cke.), which is common on dead trees and is some- 
times found on living trees in the coniferous forests of the Pacific 
Northwest, has been found to be very destructive to timbers in base- 
ments with high humidity and poor ventilation in the Northeastern 
States (26, p. 28). As a general rule, infected wood must not be 
used. 

It is extremely doubtful whether incipient decay in one of the 
laminations of ply wood can be considered an important defect. 
In the first place, the reduction in strength would be negligible. 
Furthermore, there would be but little danger of the fungus ever 
resuming its activities, because the high degree of heat and humidity 
to which the ply wood is subjected during various stages of its manu- 
facture must kill the vegetating hyphe. However, this does not 
prevent reinfection and subsequent damage if conditions for decay 


DECAYS AND DISCOLORATIONS IN AIRPLANE WOODS. 33 


again become suitable. Laminations with incipient decay should 
not be used in propellers. In this place the reduction in strength 
need not be so carefully considered as the variation from the normal 
shrinking and swelling that would result. Unequal and particularly 
unusual strains and stresses must be avoided above all things in 
propellers. 

Incipient decay usually appears as a discoloration, in some cases 
pronounced, in others so faint as to be practically invisible. Most 
of this decay in airplane lumber was actually in the tree when it was 
cut or in the logs when they left the woods. It is rare that any 
serious effort is made in the woods or at the mills to cut out incipient 
decay. When the logs are bucked and sawed the typical decay is 
usually trimmed off, leaving the less apparent incipient decay in the 
lumber. After sawing, the upper grades of lumber, which include 
airplane stock, are usually handled carefully enough at the larger 
mills to prevent further damage. 

When decay commences in a living tree, it spreads upward in the 
heartwood if the infection entered at the butt, or in both directions 
if it occurred higher on the trunk. Very rarely do the decays in the 
heartwood of living trees attack the sapwood. Beyond the typical 
_ decay, that is, where the wood is decidedly rotted, extend the incipi- 
ent stages of decay, which become less and less apparent as the dis- 
tance from the typical decay increases. Finally, the incipient decay 
ends entirely. The wood beyond is then sound. The incipient decay 
rarely ends abruptly or evenly, but usually fades out in one or more 
irregular streaks, which may be short or long. It usually extends 
only 3 or 4 feet longitudinally beyond the typical decay, but with 
certain wood-destroying fungi on some hosts the incipient decay 
may extend 15 feet or more in advance of the typical decay. Fur- 
thermore, the latter is always bounded radially by incipient decay, 
and this boundary is often irregular. Boards sawed from diseased 
trees may contain all stages of decay or incipient decay, occupying 
part or all of the board. The fact that the fungi causing decay in 
standing trees may continue their work of destruction in logs in the 
woods, or even in sawed lumber if conditions are favorable, indicates 
the necessity for having logs removed from the woods, sawed, and 
the lumber dried with reasonable promptness. 

When lumber is green the discolorations indicating incipient decay 
are more intense than when the wood has seasoned for some time. 
During the drying process the discolorations fade in varying de- 
grees. Furthermore, if a new discoloration appears within one or 
two weeks after the lumber comes from the saw it is practically 
certain that it is not caused by one of the wood-destroying fungi 
attacking the piled lumber, since the latter work more slowly. A 
sap-staining fungus or a chemical reaction is the most likely agent 
in such a case. 

Incipient decay should be detected and eliminated before the 
lumber is worked into individual parts. If the entire piece is not 
defective the sound portion can be sawed out and utilized. In 
_ marking a piece for cutting, however, it must be remembered that 
decay extends more rapidly with the grain in a tree or piece of wood 
than it does across the grain; thus, to be perfectly safe, an allow- 
ance of 2 feet should be made in the direction of the grain beyond 


34 BULLETIN 1128, U. S. DEPARTMENT OF AGRICULTURE. 


the last visible evidence of incipient decay, while across the grain 
an allowance of 2 to 3 inches will suffice. | 


TYPES OF DECAY IN LIVING SOFTWOOD TREES. 


One of the most common decays in airplane lumber is that caused 
by the ring-scale fungus (Zrametes pin (Brot.) Fr.) in the heart- 
wood of living trees. It may occur in practically any species of soft- 
_ wood, but is very common in Douglas fir, spruce, and pine. The de- 
cay, known under various common names, such as red-rot, red-heart, 
conk-rot, white honeycomb rot, pecky wood-rot, and ring-scale rot, 
is readily recognizable in its typical stage by the fact that the heart- 
wood is honeycombed with small white pits in which the wood is 
reduced to a soft fibrous mass of cellulose (in a chemical sense 
cotton is practically pure cellulose), these pits being separated by 
firm and apparently sound wood. Plate II shows typical decay in 
Douglas fir. 

While the typical decay is closely similar in appearance in various 
species of wood, there is considerable difference in the incipient de- 
cay. In Douglas fir as a general rule it appears as a pronounced 
reddish purple or olive-purple discoloration, gradually tapering and 
becoming fainter until it is lost entirely. The color is often most 
pronounced in the outermost heartwood just where it joins the sap- 
wood. In some cases it appears brownish against the red or yellow 
heartwood. At the lower limits of the incipient decay, where it be- 
gins to merge into typical decay, a close scrutiny will usually reveal 
faint indications of the cellulose pits. Vertically the discoloration 
may extend 10 feet or more in advance of the cellulose pits, but 
radially this is limited to 2 or 3 inches. The discolorations described 
are often bounded by a narrow zone of pronounced red color. Plate 
III shows discoloration in Douglas fir with the formation of cellu- 
lose pits beginning. Inrare instances the first indication of the decay 
may be the tiny golden white spots or streaks which indicate the 
initial stage in the formation of cellulose pits. In this case the 
discoloration is probably too faint to be recognized, and material of 
this kind is quite easily overlooked. 

In white and red spruce (55, p. 32) this incipient decay first ap- 
pears as a change in color from the pale yellowish or reddish brown 
of the normal heartwood to a light purplish gray, which deepens 
to a reddish brown, with the gray forming the outer boundary of 
the reddish brown discolored portions. Next, the cellulose pits ap- 
pear, visible at first as very tiny black lines following the grain of 
the wood, but soon revealing their true nature. The discoloration is 
not so pronounced as in Douglas fir. In Sitka spruce the tiny black 
lines preceding the cellulose pits are not found. 

The yellow pines first show the decay by a pronounced pink color 
which rapidly gives way to a red-brown; hence the names red-rot 
and red-heart. During this stage the wood is hard and firm. Then 
the white pits develop, although in some cases they appear so spar- 
ingly that they are readily overlooked. . 

In certain woods there is little or no discoloration with this incipi- 
ent decay. This is true with incense cedar, Port Orford cedar, and 
western red cedar, and is probably the same with other cedars. The 
first indication of the diseased condition of the wood is the appear- 


DECAYS AND DISCOLORATIONS IN AIRPLANE WOODS. 35 


ance of cellulose pits. Hence, the purplish red color commonly found 
in the heartwood of incense cedar (see p. 16) and western red cedar 
need not be mistaken for decay. | 

As yet very little is known in regard to the reduction in strength 
due to incipient decay caused by the ring-scale fungus. However, it 
seems probable that such reduction is slight until the appearance of 
the white cellulose pits; but it 1s to be remembered that pieces with 
discoloration contain hypheze which may again attack the wood, if 
suitable conditions arise. Consequently, stock with any stage of this 
decay should not be used. 

The chalky quinine fungus causes a pronounced decay in the heart- 
wood of many softwoods. The typical decay is a brownish red 
friable crumbly mass, often with conspicuous mycelium felts filling 
the cracks. This is shown in Plate IV. The incipient decay is very 
difficult to detect, as a rule. Even when the wood has been severely 
weakened the extremely faint brownish discoloration is not discern- 
ible to any but the most expert eye. However, the incipient stage 


_ of this decay in western yellow pine appears as a red-brown or pro- 


nounced brown discoloration in the pale-lemon to light orange- 
brown heartwood. The discoloration is not uniform over the entire 
affected portion, but may occur on the radial or tangential face in 
broad bands of varying intensity or even intermingled with narrow 
bands of the normal light-colored heartwood. In cross section the 
infected wood presents a mottled appearance. The horizontal limits 
of the discoloration are bounded by a narrow band of pronounced 
pink or red. At the upper limits of the incipient decay the discolora- 
tion becomes fainter until it finally disappears. The discolored wood 
seems to be hard, firm, and strong, but in reality it is seriously weak- 
ened. Plate V illustrates this condition. 

The typical decay caused by the sulphur fungus (Polyporus sul- 
fureus (Bul.) Fr.) is very similar to the foregoing. However, it is 
not confined to softwoods. It is common only in the true firs among 
the softwoods, but is very prevalent among the hardwoods, particu- 
larly the oaks. The heartwood of living and dead trees is affected. 
The incipient decay is difficult to detect, being first indicated by a 
faint brownish discoloration. 

The velvet-top fungus (Polyporus schweinitzii Fr.) also causes a 
reddish brown friable rot, which is, however, confined to the butt and 
roots of the tree. The mycelium felts are very fine and inconspicuous. 
Only softwoods are affected. Normally the incipient decay is very 
difficult to detect. It first becomes evident in Sitka spruce ® as pale- 
yellow to lemon-yellow streaks or spires extending longitudinally 
beyond the light yellowish to reddish brown discoloration which 
characterizes the more visible incipient decay. In the latter stage a 
softening of the wood isapparent. In Douglas fir the incipient decay 
is first evident as a faint yellowing or browning of the normal heart- 
wood. This or an exactly similar decay in western red cedar is first 
indicated by a decided deepening in the color of the normal brownish 
heartwood. The discolored zone often extends horizontally for sev- 
eral inches around the typical decay and for a foot or more in ad- 
vance of it. The discoloration may be confused with the normal 


*The description of the decay in this species caused by Polyporus schweinitzii is based 
- on notes furnished to the writer through the courtesy of E. E. Hubert. 


36 BULLETIN 1128, U. S. DEPARTMENT OF AGRICULTURE. 


darker colored bands of heartwood which are found in some trees, 
but such bands are confined to a definite group of annual rings. 

_ Redwood is subject to a brown friable decay which is not con- 
fined to the butt of the tree. The fungus causing this is unknown 
(57). The first indication“of the incipient decay is a very faint 


| light brownish discoloration on the light-cherry to deep reddish 


brown heartwood. This is most readily detected on the tangential 
face in the summer wood. When the brownish discoloration is 
plainly apparent, the decay has progressed so far that the affected 
wood feels softer than the normal to the thumb-nail. The typical 
decay is dark brown in color, very soft, and easily crumbled. Thin 
crustlike mycelium felts occur along the sides of the cracks. 

These reddish brown or brown friable decays which are so difficult 
to detect in their incipient stages, particularly in woods with a pro- 
nounced reddish or brownish heartwood, reduce the strength of the 
wood far more seriously than incipient decays of the red-rot type; 
in fact, the wood may be weakened before the incipient decay is 
visible. Consequently, in cutting out such decays from lumber it is 
advisable to leave a margin of safety of at least 2 feet in a longi- 
tudinal direction beyond the last visible evidence of the incipient 
stage. 

Tiasnne cedar is very commonly decayed by the incense-cedar dry- 
rot fungus (Polyporus amarus Hedge.). ‘The typical decay con- 
sists of vertically elongated pockets, varying in length from half 
an inch to about a foot, which are filled with a brown friable mass, 
and the line of demarcation between the sound and decayed wood is 
very sharp. In some of these pockets small cobweblike or feltlike 
masses of white mycelium occur. The pockets are separated from 
each other by what appears to be sound wood, although in some 
cases streaks of straw-colored or brownish wood may extend verti- 
cally between two pockets. ‘This is especially noticeable between 
young pockets. The pockets of incipient decay are at first firm 
and very faintly yellowish brown. This color deepens slightly, and 
the wood becomes somewhat soft. The incipient decay extends but 
a short distance vertically in advance of the typical decay, and a 
distance of 2 feet beyond the last visible evidence will usually exclude 
all decay. The incipient decay is only faintly apparent, occurring 
as it does in pockets with the color in the very earliest stages differ- 
ing but slightly, when at all, from the normal wood. The fact that 
an occasional pocket may be found several feet in advance of the 
main body of decay makes this decay an exceedingly dangerous one. 
The wood, even in an incipient pocket is decidely weakened (al- 
though the intervening wood is apparently not affected), and this 
makes a weak spot that is hard to detect. Such cases are fortunately 
not common, and the fact that most incense-cedar stands are so badly 
decayed will probably preclude this species from any extensive use 
for airplane construction. Other woods are subject to similar decays. 
That found occasionally in western red cedar may be caused by the 
same fungus, while “peckiness” of bald cypress (ZYaxodiwm dis- 
tichum (Linn.) Rich.) results (33) from the work of a different 
organism (Momes geotropus Cke.). 

One of the most striking discolorations indicating decay and at 
the same time one of the most serious incipient decays is that caused 


——— a ee mC mL hCU he 


DECAYS AND DISCOLORATIONS IN AIRPLANE WOODS. oF 


by the Indian paint fungus (L'chinodontium tinctorium EK. and E.). 
This is found on the true firs in the western United States, being 
especially prevalent and severe on white fir (37). It is also exceed- 
ingly serious on western hemlock (77). 

In white fir the first indications of this decay on a radial or tangen- 

tial section are light-brown or golden tan spots or larger areas of dis- 
coloration in the light-colored heartwood, which may be accompanied 
by small but clearly distinct radial burrows, resembling somewhat 
very shallow insect burrows without the deposit of excrement. These 
burrows are not easily detected in cross section. Next, rusty red- 
dish streaks appear following the grain. Throughout this stage 
the wood appears firm and strong, but in reality is so greatly weak- 
ened that boards may separate along the annual rings when dried. 
The discoloration intensifies, the wood becomes soft, showing a de- 
cided tendency to separate along the spring wood in the annual rings, 
and finally the typical stage is reached, in which the wood is brown, 
with pronounced rusty, reddish streaks and becomes fibrous and 
stringy. Hence, the name stringy brown-rot is applied to the decay. 
The incipient decay usually extends from 2 to 6 feet beyond the 
typical decay. Plate VI shows the incipient decay. 
‘ In western hemlock the incipient decay is much harder to detect, 
because the initial discoloration above described so closely approxi- 
mates the pale-brown, slightly tinged with red, color of the normal 
heartwood. The wood first assumes a faint yellowish color, which is 
sometimes intensified by the presence of small, hardly discernible 
brownish areas. These areas later develop into the typical decay. 
The extension of the incipient decay beyond the typical decay varies 
from 1 to 5 feet. For the sake of safety 2 feet should be added be- 
yond the last recognizable yellowish discoloration in order to elimi- 
nate all incipient decay. 


TYPES OF DECAY IN LIVING HARDWOOD TREES. 


Hardwood trees are subject to very serious decays. One of the 
most important from our standpoint is the white heartwood rot (58) 
so commonly found in commercial] white-ash stock, caused by the ash 
TIomes (fomes fraxinophilus (Pk.) Sacc.).. This fungus attacks 
the heartwood of living trees and produces a very characteristic rot. 
On cross section the first indication of the decay is a light brownish 
discoloration, often difficult to distinguish from the normal grayish 
brown or reddish brown heartwood. This discoloration is most ap- 
parent in the broad bands of summer wood. Next, there is a bleach- 
ing of the spring wood, during which it turns to a straw color, and 
then small white spots or specks appear. On the radial (edge- 
grain) and tangential (slash-grain) faces these appear as small whit- 
ish spots, streaks, or blotches, usually following the grain, but some 
may be at right angles to it if the decay follows a medullary ray. 
The whitish color becomes more marked, until the entire spring wood 
is affected and appears disintegrated. Then the fibers fall apart. 
The summer wood passes through the same process, but much more 
slowly, thus during the earlier stages of the typical decay causing a 
banded appearance. The completely rotted wood is whitish or straw 
colored, very soft, and spongy, readily absorbing water. A section 


38 BULLETIN 1128, U. S. DEPARTMENT OF AGRICULTURE. 


from a white-ash longeron with this incipient decay is illustrated in | 
Plate I, right side. : 
Apparently mycelium does not occur in the brown discolored wood ~ 
in advance of the white spots. It would seem that the wood is not ~ 
weakened until the white spots are found, and the wood with the 
brown discoloration alone need not be rejected. It is an excellent 
hint for close scrutiny of an affected piece, however. The incipient 
decay is somewhat obscured in rough lumber, but is usually readily 
apparent on smooth surfaces. This stage does not extend many feet 
beyond the typical decay, and on long boards the latter will most 
likely also occur. Once the presence of the typical decay is ascer- 
tained it is a relatively simple matter to determine the hmits of the 
incipient stage. : —- 
Areas in which the wood failed to change color upon transition | 
from heartwood to sapwood (see p. 16) can be differentiated from | 
the initial stages of white-rot by their larger size, by the straw-yel- 
low color as opposed to the whitish of the decay, by the sharp line 
between the two colors, and by the fact that the spots are much 
larger, without becoming soft and spongy, than would be the case ~ 
with the decay. | 
Sweet birch and yellow birch are subject to a white heart-rot (32) 
which, although very similar to the foregoing, is caused by a ditf- 
ferent fungus, the false tinder fungus (/omes zgniarius (L.) Gill.).— 
The first indication of the incipient decay is a brown discoloration, 
not very apparent against the reddish brown heartwood. Next, 
faintly paler streaks or spots appear, which finally become a yel- 
lowish white, strikingly apparent against the dark background. ~ 
This stage is illustrated by Plate VII. In the center of these streaks | 
small spots are found in which the yellowish white wood appears 
to have collapsed. Usually the long axis of these spots is parallel to 
the grain, but in some it may be at right angles to it. The wood up 
to this time appears firm and hard. Next the white streaks merge, 
the wood becomes soft, and finally the entire affected portion of the 
heartwood is reduced to a yellowish white fibrous mass composed 
principally of cellulose, the result of the delignification by the fun- 
gous hyphe. As in the white-rot of ash, hyphe are not found in the 
brown discoloration.’ Hence, no reduction in the strength of the ~ 
wood may be expected until the very first indications of the whitish — 
streaks or spot, which may be found as much as 8 feet in advance 
of the typical decay. . 
One of the most common decays (24) on oaks and also on cer-— 
tain poplars (Populus) is the heart-rot caused by the oak fungus ~ 
(Polyporus dryophilus Berk.). The incipient decay of this whitish 
piped rot in white oak has a water-soaked appearance in the unsea- ~ 
soned wood, but when dry the discoloration becomes hazel to tawny ~ 
in color. The discoloration may extend from 1 to 10 feet in advance ~~ 
of any other indication of the decay. The next stage of the decay, 
which is best seen on a radial face, is characterized by whitish spots — 
or streaks, usually following the medullary rays, which produce a ~ 
mottled appearance of the wood. This mottling is the result of a — 
delignification process; that is, the lignin is removed from the wood, 
leaving only the cellulose. In the final stages the decayed wood is 
firm, with a white, stringy appearance, and the delignification is 
practically complete. eo 


DECAYS AND DISCOLORATIONS IN AIRPLANE WOODS. 39 


A somewhat similar rot in oaks (34) is the honeycomb heart-rot 
(Stereum subpileatwm B. and C.). As in the whitish piped rot, the 
first indication of this decay in white oak is a slight water-soaked 
appearance of the fresh heartwood, and when dry this “soak” be- 
comes a tawny color. Next, light-colored isolated areas appear in 
the tawny discolored wood, and pronounced delignification occurs. 
This is indicated by the appearance of very small irregular whitish 
patches in the light-colored areas. These patches develop into small 

its with their long axes parallel to the grain of the wood, and they 
increase in number until the affected wood is completely occupied. 
The pits are from one thirty-second to one-fourth of an inch wide 
by one-fourth to five-eighths of an inch long, and lined with cellulose 
fibers. At this stage the appearance of the decay is similar to the 
red-rot in softwoods previously described. Later the cellulose lining 
may disappear. The wood is probably not weakened by this decay 
until the light-colored areas appear in the tawny discoloration. 

An incipient decay is sometimes encountered in African mahog- 
any, the cause of which is unknown to the writer. This decay ap- 
pears as light-yellow, brown, or merely lighter brown closely crowded 
spots or flecks on the reddish-brown heartwood. These flecks vary 
from one-sixteenth to one-quarter of an inch long and are several 
times longer than broad, the long axis corresponding with the direc- 
tion of the grain in the wood. Such wood is weakened. 


TYPES OF DECAY IN LOGS AND LUMBER. 


In addition to the wood-destroying fungi which normally attack 
living trees, and which may continue to decay the wood after the 
tree is cut, there are fungi which grow only or principally on wood 
in the form of logs or lumber. Owing to their destructiveness, some 
of these deserve more than passing mention. Although it is true 
that damage caused by such fungi is due to improper handling of 
the timber during the course of manufacture and utilization, unfor- 
aaRely such improper handling does occur and must be reckoned 
with. 

Softwood logs and lumber.—One of the most important of these 
fungi is that which causes dry-rot in stored logs or lumber and in 
timber in structures (22). The term “dry-rot” is loosely applied 
to cover almost any type of decay, but. it is correctly applicable 
only to the work of the dry-rot fungus (Merulius lacrymans (Wulf.) 
Fr.). This decay is more common on coniferous woods than on 
hardwoods. The incipient decay appears as a yellow-brown dis- 
coloration not easy to detect. Wood with typical decay is yellow to 
brown in color, much shrunken and cracked, and is so badly disin- 
tegrated that it can be easily crushed to a powder. Both sapwood 
and heartwood are attacked. 

Another common decay on logs and sawed lumber, particularly 
on railroad ties, is the brown-rot (62) caused by the brown Lenzites 
(Lenzites sepiaria (Wulf.) Fr.), which is practically confined to 
coniferous wood. The typical decay is brown, friable, and easily 
reducible to a powder. In the early stages of decay infected wood 
is darker in color than the normal. Sometimes the early spring 
wood of the annual rings may be completely decayed, while the 


40 -BULLETIN 1128, U. S. DEPARTMENT OF AGRICULTURE. 


summer wood is scarcely affected. In this condition the wood sep- J 
arates readily along the annual rings. 4 
Hardwood logs and lumber.—Certain fungi (Polystictus versi- 


color (L.) Fr., Sterewm hirsutum (Willd.) Pers., and others) cause a — 


sap rot very difficult of detection in its incipient stage. The typical 
decay is very light in weight, white in color, rather soft, and easily 
broken in the hands. But since the first indication of this decay is 


a faint whitening of the diseased wood and white is the normal | 


color of most sapwoods, it is apparent that the initial stages may 
be readily overlooked. At the same time the wood is decidedly re- 
duced in strength. The decay is most common on hardwoods, but 
also occurs to some extent on softwoods. Fortunately none of the 
fungi causing this white sap-rot attack living trees of the species 
which furnish airplane timber. 

Red-gum logs when left in the woods for any considerable time 
are subject to a very serious sap-rot (59) caused by the smoky Poly- 
porus (Polyporus adustus (Willd.) Fr.). The heartwood is com- 
paratively durable. Boards cut from diseased logs are very char- 
acteristic and striking in appearance. Normally, red-gum sapwood 
is a light yellowish white, commonly with a reddish tinge. The sap- 
wood in a decayed board has a number of various-colored streaks or 
lines irregularly distributed from the end of the board toward the 
middle. ‘These streaks are light orange at first, but in the more ad- 
vanced decay are a very light straw color (in fact, almost white) and 
are intermingled with lines and patches of bluish gray and the nor- 
mal-colored sapwood. Black zigzag lines may extend from the ends 
of the board for a distance of 2 inches or more parallel to the grain. 
The general consistency of sapwood with this incipient decay, which 
may extend 2 or 3 feet in advance of the typical decay, is firm and 
solid. Sapwood with the typical decay is badly broken down, being 
soft and pulpy and without firmness. . 

This and other sap rots may be prevented by shortening the dry- 
ing period in the woods. Coating the ends with hot coal-tar creosote 
immediately after the logs are cut is also effective. Where possible, 
all freshly cut logs, particularly those cut during the spring and 
summer, when the rot develops best, should be peeled. Sap rots simi- 
lar to those found in the red gum are found in tupelo gum (Vyssa 
sylvatica Marsh) and in maple. 


DECAY IN FINISHED AIRPLANES. 


Little information about decay in finished airplanes is available. 
In the past there has been very small chance for airplanes to decay, 
because the completed machines rarely ever were stored, and their 
life in use was a relatively brief one; but since the conclusion of the 
World War immense quantities of airplane material have been placed 
in storage, and the average life of the machines has been materially 
increased by changes in construction. Under average conditions 
there should be practically no damage to finished airplanes by decay. 
When in use there is little danger from this source, owing to the fact 
that when not actually in flight the machines are properly housed. 
The wooden parts in the interior of the wings and around the en- 
gine are most susceptible. In these places there is an increased tem- 
perature and relative humidity. Keeping the machines in a dry 


DECAYS AND DISCOLORATIONS IN AIRPLANE WOODS. 41 


place when not in use will suffice in most climates. ‘There is’ more 
danger in humid tropical or semitropical regions, particularly to 
seaplanes. 

Serious loss can easily result to machines through improper han- 
dling while being stored or shipped. Airplanes are usually knocked 
down for storing and shipping; that is, the machine is taken apart, 
and the individual assemblies, such as the wings, tail surfaces, and 
fuselage, are handled separately. When shipped, these parts are 
carefully wrapped in heavy paper and packed in solid crates. If 
these crates are left out in the air, cracks open up between the boards, 
water may get in, and then the trouble commences. Once damp, it 
is almost impossible for the mass of paper wrappings to dry out un- 
less the crate is completely unpacked. Varnish or dope does not 
prevent the taking up of moisture, so that the wood soon attains a 
moisture content sufficient for the erowth of molds and wood-destroy- 
ing fungi, while the other conditions within the crate, such as lack 
of air circulation with the resulting high humidity and the higher 
temperatures, are ideal for the development of these organisms. 
Even before the wood is decayed the elements of the ply wood are 
very likely to separate, owing to the action of moisture and molds on 
the glue. Even water-resistant glues can not permanently withstand 
such conditions. 

There is no cure for decay, once it has started. The damaged 
part can be replaced and further destruction prevented, but the con- 
stant aim should be not to let decay begin. Material should not be 
kept in packing cases any longer than is necessary. The practice 
of leaving packing cases containing airplanes or spare parts in the 
open for several months can not be too severely condemned. 

When put in storage, the parts should be removed from the cases 
and placed on racks, so that a complete circulation of air is possible 
around each unit or piece. The storage houses should be equipped 
with a forced-ventilation system, so that‘air of the proper humidity 
can be constantly circulated through the piles of material. The 
relative humidity should be maintained at 60 which will keep the 
wood at a moisture content of about 11 per cent, low enough to pre- 
vent decay, mold, or sap-stain. 

Circumstances will arise where planes are in use or while being 
shipped when it will be impossible to maintain proper conditions to 
prevent deterioration. In the warm climate and high humidity of 
tropical or semitropical regions in particular this will be true. It 
is advisable to have planes for use under such conditions constructed 
from a durable wood such as Port Orford cedar. Where this can 
not be done, methods should be employed to make the other species 
more durable. 

Wood may be moisture-proofed by the application of aluminum 
leaf. This not only prevents decay, since the wood is kept dry, but 
protects the glue joints from the action of moisture and mold. 

As a last resort, the wood could be treated with preservatives to 
prevent decay. These liquids are most effective when forced into 
the wood under pressure. Consequently the completed individual 
wood parts would have to be treated before assembly. Sodium 
fluorid could be used on parts to be glued, while coal-tar creosote 
could be applied to the others. The most highly efficient of all, 


42 BULLETIN 1128, U. S. DEPARTMENT OF AGRICULTURE. 


mercuric chlorid, is unfortunately a deadly poison, corrodes metal, 
and is very difficult to handle. The subject of preservative treat- 
ment is one about which little is known as applied to airplanes. 4 

Little information is available as to what fungi actually cause 
decay in finished airplanes or as to the types of decay found. Un- ~ 
doubtedly the fungi most concerned are those commonly attacking ~ 
the manufactured product, such as the dry-rot fungus, the brown ~ 
Lenzites, or the rose-colored Fomes. Fungi decaying the heartwood 
of living trees are not commonly found. When they do appear, this 
is practically proof positive that the manufacturer used wood with 
incipient decay in the fabrication of the wooden parts. 


SUMMARY. 


Among the softwoods or conifers the most valuable for airplane 
construction are red, white, and Sitka spruce, the last being most 
important on account of its large size and the consequently greater 
proportion of clear lumber that can be obtained. A. splendid substi- 
tute for spruce, and its superior where durability must be consid- 
ered, is Port Orford cedar. However, the supply of this wood is 
limited. Douglas fir, which is much heavier than spruce and there- 
fore not so desirable, is also extensively used. In those parts of an 
‘airplane frame requiring great strength and toughness, hardwoods 
are used. White ash is best, but white oak, hard maple, and rock 
elm may be substituted. Hickory is principally used for tail skids. 
Black walnut and true mahogany are unsurpassed for propellers, 
but yellow birch, sweet birch, African mahogany, black cherry, hard 
maple, and white oak are acceptable substitutes. As the supply of 
timber diminishes in the future, a wider variety of woods will be 
acceptable for airplane construction. 

All wood is subject to defects, of which one of the most serious is 
decay; but other defects which reduce the strength of timber must 
be recognized. Among these can be mentioned spiral and diagonal 
grain, specific gravity that is too low or too high, brashness caused 
by excessive temperatures during steaming or kiln drying, com- 
pression failures, shakes, pitch pockets, and insect galleries. | 

Decay in its incipient stage is often not readily recognized; but — 
wood with incipient decay must not be used in airplane construction, 
since infected wood may be reduced in strength. Furthermore, the 
decay may continue if suitable conditions arise. ‘The first indi- — 
cation of decay is usually a discoloration of the infected wood, but ~ 
not all discolorations result from decay. Marked discoloration of — 
the wood, particularly the sapwood, usually accompanies pith-ray 
flecks and wounds made by lightning and sapsuckers. Conditions 
favorable for decay also promote sap stains. These discolorations of 
the green sapwood of various softwoods and hardwoods occur in two 
ways: (1) By an oxidation of the organic compounds in the cells © 
of the sapwood when exposed to the air and (2) by the attack of | 
sap-staining fungi, the hyphe of which feed on the organic com- 
pounds in the cells of the sapwood without attacking the cell walls 
except to a negligible extent. The discolorations are confined to the 
se as a rule, but occasionally the sap-staining fungi, may dis- 
color the heartwood slightly. For practical purposes wood so dis- 
colored is not reduced in strength. : 


DECAYS AND DISCOLORATIONS IN AIRPLANE WOODS. 43 


The discolorations resulting from incipient decay may be found 
in the sapwood or heartwood. Incipient decay extends for varying 
distances beyond the typical decay. In cutting out this defect it is 
advisable to leave a margin of safety of at least 2 feet in a longi- 
tudinal direction beyond the last visible evidences of the incipient 
decay, in order to remove all infected wood. This margin of safety 
is particularly important with brown or red-brown friable decays, 
since infected wood may be dangerously weakened by them while the 
incipient stage is still practically invisible. 

Many decays other than those described in this paper are found 
in living trees, in logs, and-in manufactured timber, but the examples 
cited include both the most important decays and the principal types. 
For most purposes it is sufficient to recognize incipient decay as 
distinguished from other discolorations or defects without deter- 
mining the causal fungus. 


oe 


a . 


PLT BER es RD ed. 
k rates de 
inp ial 9) aaa 
Peart? bes: a ‘bit hee 


rods 
; 


¢ Airhead 
ee 
dee al 
ea 
one ae 
aes ee. Z 
eth atk “wee EE : i 
oi RP SPs P ais hs 


“at at r 


tipo ee 


x stg etre 


P , 
a 
~. 
Ae 
‘ 

Ls ' 
- 
2 
‘ 
' 


- : 
Ww z 
ee oO 
<x . 
= # 3 
ae i SB 2 
Es 
oO 
pee 
o * 

om 

a, 

om 

oO 

=| 

—“ 


-STAIN IN SUGAR PINE 


SHOWING BLUE 


at the right is unstained heartwood. 
FiG. 2.—SECTION FROM A WHITE-ASH LONGERON. 
heartwood rot. 


The brownish discoloration with the small white streaks indicates 


FiG. 1.—SECTION FROM A RIB Wes, 
The dark-blue specks are the ends of the medullary rays. The pale orange colored wood 


Bul. 1128, U. S. Dept. of Agriculture. 


PLATE Il. 


Bul. 1128, U. S. Dept. of Agriculture. 


—— 


Ty ie rep PSO PRD RDA RA ITH 


ce RY EDS LLG SE en TG I ON SOP 


aceetccat 
ose 
a RS 


SECTION OF THE HEARTWOOD OF DOUGLAS Fir. 


The typical decay here shown is caused by the ring-scale fungus. 


The light-colored 


wood at the right is sound sapwood, 


A. HOEN & CO. BALTO 


— 


ER, 


= 


Bul. 1128, U.S. Dept. of Agriculture. PLATE III. 


INCIPIENT Decay IN Douatas FIR CAUSED BY THE RING-SCALE FUNGUS. 
The white spots are the beginning of the formation of cellul 
discolored zone, indicating decay. 


ose pits in the central 


i te litte 


Bul. 1128, U. S. Dept. of Agriculture. PLATE IV. 


DECAY COMMON IN THE HEARTWOOD OF PINE, LARCH, AND DOUGLAS Fir. 


This typical decay, with the characteristic conspicuous white mycelium felts, is caused by 
the chalky quinine fungus. 


PLATE V. 
A.HOEN @ CO. BALTO. 


i, 


¥ “~ er Se Ee RAR xe ° x on 


INCIPIENT DECAY IN THE HEARTWOOD OF WESTERN YELLOW PINE. 
The pale orange colored wood at the right is sound heartwood. 


The discoloration indicates the presence of decay caused by the chalky quinine fungus. 


- Bul. 1128, U. S. Dept. of Agriculture. 


pag a an Sag a ti A Ee PLR EPPS ae ne CS 


” 


PLATE VI, 


Bul. 1128, U. S. Dept. of Agriculture. 


‘ia 


Shem 2 


SAA ATES AYER S-Series tienen tives iar phere, 


OS a team RST esi 
z adhe GS 


INCIPIENT DECAY IN THE HEARTWOOD OF WHITE FIR. 


-paint fungus. Note 


dicates decay caused by the Indian 


. 


10n 1n 


the contrast 


This golden brown discolorati 


lor with the normal white wood, 


1p co 


A HOEN 


—— = 


se 


N 


Ls 


Bul. 1128, U. S. Dept. 


SECTION OF YELLOV 


The incipient decay here shown is caused by the 


LITERATURE CITED. 


(1) ANONYMOUS. 
1919. Dipping treatment for prevention of sap stain. Jn Timberman, 
var20:- no. t, P..50,: illus. 


1919. How to distinguish black ash from commercial white ash lum- 
ber. In Tech. Notes (U. S. Forest Seryv., Forest Products 
Lab.) No. D-11. 


(3) Batrey, Irvine W. 
1910. Oxidizing enzymes ana their relation to “‘sap stain’ in lumber. 
In Bot. Gaz., v. 50, p. 142-147. 


(4) Bertrs, HArorp S. 
1917. The seasoning of wood. U.S. Dept. Agr. Bul. 552, 28 p., 18 fig., 
8 pl. 
(5) LATE, RK. J. 
1919. Fungi which decay weaveshed roofs. (Abstract.) In Phyto- 
pathology, v. 9, p. 54-55. 


(6) Boyce, J. S. 
1918. Advance rot and latent defects in aeroplane timber. Jn Aerial 
Age Weekly, v. 7, p. 674-675, 691. Bibliography, p. 691. 


(7) 1918. Detection of decays, advance rots and other defects in wood. 
In Bur. Aircraft Production, Inspection Manual, QT-16, 6 p. 


(8) 1920. The dry-rot of incense cedar. U.S. Dept. Agr. Bul. 871, 58 p.. 
3 fig., 3 pl. Literature cited, p. 57-58. 


: (9) Brick, G. 

1911. Zythia resinae (Fr.) Karst. als unangenehmer Bauholzpilz. In 
Jahresber. Angew. Bot-, Jahrg. 8, 1910, p. 164-170. Biblio- 
graphical footnotes. 


(10) Brown, H. P. 
1913. Pith-ray flecks in wood. U. S. Dept. Agr., Forest Serv. Cire. 
215,15 p., 6 pl. References, p. 14-15. 


(11) Burks, H. E. . 

1905. Black check in western hemlock. U. 8S. Dept. Agr., Bur. Ent. 
Circ, 61, 10 p., 5 fig. 

/(12) Dunwap, FREDERICK. 

1906. Kiln-drying hardwood lumber. U. S. Dept. Agr., Forest Serv. 
Circ. 48, 19 p., 4 fig. 


1914. Density of wood substance and porosity of wood. Jn Jour. Agr. 
Research, v. 2, p. 423-428. 


1912. Die technischen Higenschaften der Holzer. Jn Handbuch der 
Forstw. Aufl. 3, Bd. 2, p. 342442, 3 fig. Tiibingen. Biblio- 
graphical footnotes. 


(15) Fucus, GILBERT. 

. 1905. Uber das Ringeln der Spechte und ihr Verhalten gegen die 
kleineren Forstschidlinge. In Natiirw. Ztschr. Land-u. 
Forstw., Jahrg. 3, p. 317-341, 7 fig., pl. 7. Bibliographical 

footnotes. 
16) GtLover, H. M. 
1919. Spruce red wood. In Indian Forester, v. 45, p. 243-245. 


45 


46 


(17) 


(18) 


(19) 
(20) 


(21) 


(22) 


(24) 


(25) 


(30) 


(31) 


(32) 


(33) 


(34) 


BULLETIN 1128, U. S. DEPARTMENT OF AGRICULTURE. ; 


GREENE, CHARLES T. ; 
1914. The cambium miner in river birch. In Jour. Agr. Research, 
v. 1, p. 471-474, pl. 60-61. 


GROOM, PERCY. 
1915. “Brown oak” and its origin. Jn Ann. Bot., v. 29, p. 393-408, 


1920. Brown oak. Jn Quart. Jour. Forestry, v. 14, p. 108-109. 


GROSSENBACHER, J. G. 
1910. Medullary spots: A contribution to the life history of some 
cambium miners. N. Y. Agr. Exp. Sta. (Geneva) Tech. Bul. 15, 

p. 49-65, 5 pl. Bibliographical footnotes. 


1915. Medullary spots and their cause. In Bul. Torrey Bot. Club, v. 
42, p. 227-239, pl. 10-11. 


HARTIG, ROBERT. 
1962. Der echte Hausschwamm ... Aufl. 2. vii, 105 p., 33 fig. (partly 
col.). Berlin. : 


HEDGcocK, GEORGE GRANT. 
1906. Studies upon some chromogenic fungi which discolor wood. In 
Mo. Bot. Gard. 17th Ann. Rpt., p. 59-114, illus., pl. 3-12. 
Bibliographical footnotes. 


and Lone, W. H. 
1914. Heart-rot of oaks and poplars caused by Polyporus dryophilus. ~ 
In Jour. Agr. Research, v. 3, p. 65-78, pl. 8-10. Literature 
cited, p. 77 
Howarp, N. O. A 
1922. The control of sap-stain, mold, and incipient decay in green 
wood, with special reference to vehicle stock. U. S. Dept. 
Agr. Bul. 1037, 55 p., 26 fig., 2 pl. Literature cited, p. 52-55. 
Hoxik, FI. J. 


1915. Dry-rot in factory timbers. 107 p., 70 fig. Boston. 


HUBERT, ERNEST BE. 
1921. Notes on sap-stain fungi. In Phytopathology, v. 11, p. as 
4 fig., pl. 7. Literature cited, p. 223-224. 


HuMPHREY, C. J. 
1917. Timber storage conditions in the Eastern and Southern States 
with reference to decay problems. U. S. Dept. Agr. Bul. 510, 

43 p., 41 fig., 10 pl. Bibliographical footnotes. 


KHAN, A. HAFIZz. 
1919. Red wood of Himalayan spruce (Picea morinda Link). 
Indian Forester, v. 45, p. 496-498. 


IXOEHLER, ARTHUR. 
1917. Guidebook for the identification of woods used for ties and 
timbers. U. S. Dept. Agr., Forest Serv., ‘79 pD.,. 8 fig. 31 pl 

11 maps. 


1918. The “ grain” of wood wale special reference to the direction ¢ 
the fibers. Jn Bur. Aircraft Production, Inspection Manu: 
QT-18, 8 p., 12 fig. 


LInDROTH, J. IVAR. j 
1904. Beitriige zur Kenntnis der Zersetzungserscheinungen des Birken 

holzes. In Naturw. Ztschr. Land-u. Forstw,, Jahrg. 2, p. 7 

406, 7 fig. Bibliographical footnotes. 


LonG, WILLIAM H. ig 
1914. A preliminary note on the cause of “pecky” cypress. (Atk 
stract.) Jn Phytopathology, v. 4, p. 39. a 


1915. A honeycomb heart-rot of oaks caused by Stereum subpileat 
In Jour. Agr. Research, v. 5, p. 421-428, pl. 41. Bibliogr. 
cal footnotes. *¢ 


DECAYS AND DISCOLORATIONS IN AIRPLANE WOODS. 47 


35) McATEE, W. L. 
1911. Woodpeckers in relation to trees and wood products. U. S. 
; Dept. Agr., Biol. Survey Bul. 39, 99 p., 44 fig., 12 pl. Bibliog- 
raphy, D. 55-56. 


a6) MacMrzan, H. RB. 
1916. Timber trade of South Africa. In: Timberman, v. 17, no. 8, p. 
34-389. 


(37) MEINECKE, E. P. 
1916. Forest pathology in forest On gee ais U. S. Dept. fare Bul. 275, 
63 p. Bibliographical footnotes. 


(38) Mincu, Ernsv. 

1905-1906. Die Blaufiiule des Nadelholzes. Jn Naturw. Ztschr. Land- 
u. Forstw., Jabrg. 5, p. 5381-573; Jahrg. 6, p. 32-47, 297-323, 
33 fig. Bibliographical footnotes. 


(39) NecER, F. W. 
1910. Die Vergriinung des frischen Lindenholzes. Jn Natiirw. Ztschr. 
Yorst u. Landw., Jahrg. 8, p. 305-313, 2 fig. 


(40) 1911. Die Rotung des frischen Erlenholzes. Jn Natiirw. Ztschr. Forst- 
u. Landw., Jahrg. 9, p. 96-105, 2 fig. 


(41) Newtin, J. A., and Witson, T. R. C. 

‘ 1919. The relation of the shrinkage and strength properties of wood 
to its specific gravity. U.S. Dept. Agr. Bul. 676, 35 p., 9 fig. 
(partly fold.). 


(42) OAKLEAF, H. B. (revised by Boyce, J. S.). 

: 1918. Important defects in wood. Jn Bur. Aircraft Production, In- 

spection Manual, QT-10a, 18 p., 10 figs. 

(43) Pratt, Merrit B. 

1915. The deterioration of lumber. Calif. Agr. Exp. Sta. Bul. 252, p. 
301-320, § fig. 


(44) Recorp, SAMUEL J. 
191). Pith flecks or medullary spots in wood. Jn Forestry Quart., v. 
9, p. 244-252, illus. References cited, p. 251-252. 


(45) 1914. The mechanical properties of wood ...KHd.1. xi, 165 p., 52 
fig., front. New York. Bibliography, p. 145-160. 


(46) 1918. Defects in airplane woods. In Sci. Amer., v. 119, p. 212, 218- 
219, illus. 


47) 1919. Identification of the economic woods of the United States... 
Hid. 2. ix, 157 p., 15 fig., 6 pl. New York. References, p. 
109-117. Bibliography, p. 119-125.° 


(48) RorH, FIvserr. : 

1895. Timber: An elementary discussion of the characteristics and 
properties of wood. U. S. Dept. Agr., Div. Forestry Bul. 
10, 88 p., 49 fig. 


(49) RubDELorr, M. 

1897. 1899. Untersuchung tiber den Einfluss des Blauwerdens auf die 
Festigkeit von Kiefernholz. Sonderabdruck aus den Mitt. K. 
{echnischen Versuchsanstalten, 1897, p. 1-46, 55 fig.; 1899, p. 
209-239, 9 fig. 


(50) — CAROLINE. 
1911. Blue stain on lumber. Jn Science, n. s. v. 34, p. 94-96. 


(51) 1911. Uber die Hinwirkung des Saure- und Alkaligehaltes des Nihr- 
g bodens auf das Wachstum der holzzersetzenden und holzver- 
firbenden Pilze; mit einer Hrortung tiber die systematischen 
Beziehungen zwischen Ceratostomella und Graphium. Jn 
Naturw. Ztschr. Forst- u. Landw., Jahrg. 9, p. 429-466, 22 fig. 
Ono: pl. 


48 BULLETIN 1128, U. S. DEPARTMENT OF AGRICULTURE. 


~ 
é 


(52) ScHRaAMM, W. H. -j 
1906. Zum Vergrauen der Holzer. Jn Jahresber. Angew. Bot., Jahre. 4 
1906, p. 140-153. Bibliographical footnotes. : 


(53) 1907. Zu den Farbenangaben bei Hélzern. Jn Jahresber. Angew. Bot. 
Jabrg. 4, 1906, p. 154-163. Bibliographical footnotes. 


(54) 1907. Zur Holzvergilbung. Jn Jahresber. Angew. Bot., Jahrg. 4, 1906 
p. 116-139. Bibliographical footnotes. 


(55) ScHRENK, HERMANN VON. ‘ 
1900. Some diseases of New England conifers. U. S. Dept. Agr., Diy. 

Veg. Phys. and Path. Bul. 25, 56 p., 3 fig., 15 pl. Bibliographi 

cal footnotes. 


(56) 1903. The “bluing” and the “red rot” of the western yellow pine, 
with special reference to the Black Hills Forest Reserve 
U. S. Dept. Agr., Bur. Plant Ind. Bul. 36, 40 p., 14 pl. (partly 
col.). 


(57) 1903. The brown-rot disease of the redwood. In U. S. Dept. Agr., 
Bur. For. Bul. 38, p. 29-31, pl. 10-11. 


(58) 1908. A disease of the white ash caused by Polyporus fraxinophilus. — 
U. S. Dept. Agr., Bur. Plant Ind. Bul:-32; 20 py tiie. 6 


(59) 1907. Sap-rot and other diseases of the red gum. U. 8S. Dept. Agr., | 
Bur. Plant Ind. Bul. 114, 37 p., 8 pl. 


(60) SPARHAWK, W. N. 
i919. Supplies and production of aircraft woods. National Advisory 
Commit. for Aeronautics Rpt. No. 67, 62 p., 28 maps. (Pre- 

print from 5th Ann. Rpt.) ! 


(61) SPAULDING, PERLEY. 
1906. Studies on the lignin and cellulose of wood. Jn Mo. Bot. Gard. 

17th Ann. Rpt., p. 41-58, pl. 1-2 (col.). Bibliographical 

footnotes. 


(62) 1911. The timber rot caused by Lenzites sepiaria. U.S. Dept. Agr, 
Bur. Plant Ind. Bul. 214, 46 p., 3 fig., 4 pl. Bibliography, p. | 
31-37. 


(63) TIEMANN, HARRY DONALD. 
1907. The strength of wood as influenced by moisture. U. 8 .Dept. 

Agr., Forest Serv. Circ. 108, 42 p., 6 fig. Bibliographical foot 

notes. 


(64) 1912. Principles of drying lumber at atmospheric pressure and humid 
ity diagram. U.S. Dept. Agr., Forest Serv. Bul. 104, 19 p. 
2 fig. (1 fold.). 


(65) [1917]. The Kiln Drying of Lumber ... xi, 316 p., 54 fig. in fé x 
and on pl., 8 pl. (1 fold.). Philadelphia, London. 


(66) 1917. The theory of drying and its application to the new humidit} 7 
regulated and recirculating dry kiln. U. 8. Dept. Agr. Bul 

509, 28 p., 3 fig. . 4 

(67) TuBEurF, C. VON. 
1897. Die Zellginge der Birke und anderer Laubhilzer. Jn Forstl 
Naturw. Ztschr., Jahrg. 6, p. 314-319, 3 fig. 


(68) U. S. Dept. Agr., Forest Products Laboratory. 
1918. Information for inspectors of airplane wood. Bur. Aircraf af 
Production, Te ae Dept., 72 p., 52 fig., 2 pl. Washington 

D. C. 4 

(69) 1919. Wood in aircraft construction. Reprinted from Aireraft De 
sign Data, Bur. Construction and Repair, Navy Dept., as 

82 fig. Washington, D.C. 


(70) WAGNER, JOSEPH B. 
1917. Seasoning of Wood... xiii, 274 p., 101 fig. (1 fold.). 
-York. Bibliography, p. 251. 


DECAYS AND DISCOLORATIONS IN AIRPLANE WOODS. 49 


(71) WeETR, JAMES R., and HuBERT, ERNEST EH. 
j 1918. <A study of heart-rot in western hemlock. U.S. Dept. Agr. Bul. 
722, 39 p., 18 fig. Bibliographical footnotes. 


{72) Weiss, Howarp F., and BARNUM, CHARLES T. 
1911. The prevention of sap stain in lumber. U. S. Dept. Agr., Forest 
Serv. Circe. 192, 19 p., 4 fig. 


473) Wirson, T. R. C. 

; 1920. The effect of kiln drying on the strength of airplane woods. 
National Advisory Commit. for Aeronautics Rpt. No. 68, 69 
p., 22 fig.; 9 pl, 27 tables. (Preprint from 5th Ann. Rpt.) 


(74) ZxExterR, SANFORD M. 

1917. Studies in the physiology of the fungi—III. Physical proper- 
ties of wood in relation to decay induced by Lenzites saep- 
jiaria Fries. Jn Ann. Mo. Bot. Gard., v. 4, p. 938-164, 1 fig., 
11 charts (partly double), pl. 9-18. Bibliography, p. 154-155. 


(75) 1920. Humidity in relation to moisture imbibition by wood and to 
spore germination on wood. Jn Ann. Mo. Bot. Gard., v. 7, 
p. 51-74, 5 fig., pl. 1. Literature cited, p. 72-73. 


- 


- 


DEFECTS OF WOOD REFERRED TO IN THIS BULLETIN, ARRANGE 


sap- a 


16, i 


16, 3 


BY SPECIES. 
HARDWOODS. Page. 
Poplar: Brown spots, pith-ra 
Alder: Hed-stant= 43a 23 flecks______ Z ae . ese. p 
Ash, a Ae teen nae 8, 13 Whitish rot, heartwood____ 
white: ack spots or ee ee 
blotches, sapsucker rhs peri aaa ind’s- eye 
wounds__—-_-____-_- 20 Sapsucker “wounds. anes 
Bluish gray stain, ~ [0° 
Sieamine se 10 
Re a 39 SOFTWOODS, 
Straw-yellow heart- —__—| Geaur: Blue-stain, sapwood_____ 
wood ~_---~--~------ 16, 3 Red-rot, heartwood 
White-rot, heartwood __ 37 : ae ene 
Basswood: Brown spots, pith- Cedar, Rasa Brownish red 
ray feds — 820 CA eae 21 stall —~-___~________ a 
Pein Mies tO, tne Be 5 23 Brown-rot pockets, heart- 
Birch: Pith-ray flecks__________ 21 wood 22 eee 
Reddish yellow stain_______ 23 Lightning rings_-__________ 
Birch, sweet: White-rot, heart- es ae Race, -------- 
WOO0U > >. +5 2 ee oe 88 -ToU, Nearitwooa 2 
yellow: Blue-stain, Sap-. Cedar, Port Orford: Red-rot, 
WOE [steak te eee 29 heartwood _.=2 4 eee 
Brown spots, pith-ray Cedar, red: White streaks in 
= ioe 6: Bue ee ee = heartwood 2.2 eee 
ecay — -——-— — -— v = ° ey 
White-rot, heartwood__ 3 See ea Ee rot 
Cherry cee spots, pith-ray Zi Purplish heartwienas ae! 
Reddish yellow stain______ 23 Ree ae 
Elm: Gray color, steaming_____ 10 | ee eee 
Gum, red: Bluish stain________ 2 Red-rot, heartwood 2 
Orange to straw-colored rot, ——— Paisano 5 | Pecki- 
sapwood. -. O2aat ae 40 0 rtwood_-__________ 
Sap stains, susceptibility___ 29 | Douglas fir: Blue-stain, sap- 
Gum, tupelo: Orange to straw- wood |. ee 
colored rot, sapwood_________ 40 Color variations in heart- 
Hickory: Sapsucker wounds____ 20 wood due to growth_____- 
Linden, European: Green-stain_ 23 Decay _.... eee 
Mahogany, African: Yellow- Decay during shipment____ 
brown rot, heartwood________ 39 Lightning rings: eee 
Maple: Brown _ spots, . pith-ray Pitch pockets 2222322.e=e : 
fleelss, > #152 a a ee 4. Reddish brown rot, heart- 
Reddish yellow stain_______ 23 W000 .... 35 ee 
Maple, hard: Black-stain, sap- Red-rot, heartwood_____-__ 
sucker injury 2 2 20 Splintering tendency_______ 
Brown spots, pith-ray flecks_ AL “Yellow fir”. 22 
Maple, soft: Black-stain, sap- Fir: Blue-stain, sapwood_______ 
sucker, Ajay 20 Brown discoloration, heart- 
Brown spots, pith-ray flecks_ 21 wood, stringy brown-rot__ 
Oak, sie ag ag Brown heart- ns Brown-rot, heartwood_____- 
WO0G. <0. 2. ee eee : 
white: Blackish brown stain, uit, Vee ‘Stringy brown: 
Steaming) 10 an 
Blue-black to gray-black Tarn or att nen 1 
stain, immersion in Lightning rings 
Gaiters oc. deste 45 | Hemlock, western: Black check_ 
Brown-rot, heartwood__ 25 Brown discoloration, heart- 
Honeycomb, heart-rot__ 29 wood, stringy brown-rot__ 
Tawny color, heart- ieee Pine: One -red_ stain, 
Wood 2262. en = SE : wood. _____-+___ eee 
Whitish piped rot, heart- Pink color, sapwood —_----~ 
wood: -)44.._ 54 ae 38 


50 


Violet stain _.____.. 23a - 


Pine, southern yellow: 
Brain, sapwood 1 -_ 
sugar: Blue-stain, sapwood_ 

Brown-stain, sapwood__ 
Dirt streakse occ ee 
TS 2 i ee cae 
Pink heartwood —-___-__ 
Orange-red stain______- 
western white: Blue-stain__ 
western yellow: Red-brown 
rot, heartwood_____- 
Red-rot, heartwood —___ 
white: Blue-stain, sapwood_ 
Brown to black blotches, 
Moor Wnrnse lo 

OS a 


Rs OE ee ae 

Spruce: Compression failure 
caused by— 

Faulty assembly___________ 

eee 


_ Page. 


DECAYS AND DISCOLORATIONS IN AIRPLANE WOODS. 


Spruce: Compression failure 
caused by—Continued. 

pceam, bending — -. 222. 
Sy ha a ET a a a 
Spruce: Compression wood____-_ 
Bec: pockers 8 
Spruce, Himalayan: Red heart- 
meyer we os Ed ee ee 


Spruce, red: Red-rot, heart- 
WOOO 2 ony ha eee 
Spruce, Sitka: Blue-stain, sap- 

2 Oi AR a tiple det «of 


Decay during shipment_____ 
Reddish brown-purple color, 
benining 2 ots et We ere 
Reddish brown rot, heart- 
ETO | ERS Tee 2 2 TE SAC 

hed heartwood 
Red-rot, heartwood___..____ 

- Red-stain, sapwood ________ 
Spruce, white: Red-rot, heart- 
BONG eee tse Sn ec eee me 


ORGANIZATION OF THE UNITED STATES DEPARTMENT OF 


AGRICULTURE. 
Secretary .of. Agriculture_-.__ ee HENRY C. WALLACE. 
Assistant’ Secretary) 22 ae C. W. PUGSEEY. 
Director of SGentific Worle... 4). .D> BALL. 
Director of Regulatory Work__.________~- 
Weather Baresi. See Oe eae CHARLES W. Marvin, Chief. 
Bureau of Agricultural Economics_______- Henry C. Taytor, Chief. 
Bureau of Animal Industry_____=.__-____. JOHN R. MOHLER, Chief. 
Buréat of Plant, Inaustry see oe ee WILLIAM A. TAYLOR, Chief. 
Forest. SCrvice twig es sat ee eh ae . W. B. GREELEY, Chief. 
Bureau OF ORCI) 3 te Ae WALTER G. CAMPBELL, Acting Chief. 
BuUreat.of Sous... 2 a ee eee MILTON WHITNEY, Chief. 
Bureawt of Hntomotlogy 2. - ee ae L. O. Howarp, Chief, 
Bureau of Biological Survey__—______.__-. EK. W. NELSon, Chief. 
Bureau of Public Roadie. 2 oa THomMAS H. MAacDonatp, Chief. 
Fized-Nitrogen Research Laboratory______ F. G. CoTTREtx, Director. 
Division of Accounts and Disbursements__ A. ZAPPONE, Chief. 
Division of Publications’ = Se JOHN L. Cosss, Jr., Chief. 
TADIONY 2 4. ae CLARIBEL R. BARNETT, Jibrarian. 
States Relations Service_____-___-__._____. A. C. True, Director. 
Federal: Horticultural’ Board... = 2a = C. L. MAriattT, Chairman. 
Insecticide and Fungicide Board_________- J. K. Haywoop, Chairman. 
Packers and Stockyards eyiibatiaties vo MorriL1, Asistant to the 
Grain Future-Trading Act Administration_- Secretary. 
Office of the Solicitor. = Ss R. W. WILLIAMS, Solicitor. 


This bulletin is a contribution from— 


Bure of Plant Industry = eee WILLIAM A. TAYLOR, Chiet. 
Office of Investigations in Forest Pa- HaveN Metcatr, Pathologist im 
thology. Charge. 
Bee 


ADDITIONAL COPIES 


OF THIS PUBLICATION MAY BE PROCURED FROM 
THE SUPERINTENDENT OF DOCUMENTS 
GOVERNMENT PRINTING OFFICE 
WASHINGTON, D. C. 

AT 


20 CENTS PER COPY 


PURCHASER AGREES NOT TO RESELL OR DISTRIBUTE THIS 
COPY FOR PROFIT.—PUB. RES. 57, APPROVED MAY 11, 1924 


UNITED STATES DEPARTMENT OF AGRICULTURE 


| Z-}) DEPARTMENT BULLETIN No. 1131 ,%. 


Washington, D. C. PROFESSIONAL PAPER 


February 13, 1923 


THE FORMATION AND PATHOLOGICAL ANATOMY OF FROST RINGS IN 
CONIFERS INJURED BY LATE FROSTS. 


By ArtHurR 8. Ruoaps, formerly Assistant in Forest Pathology, Office of 
Investigations in Forest Pathology, Bureau of Plant Industry. 


CONTENTS. 
Page. Page. 
1 es 7 a a a rs 1 | Anatomical structure of the frost 
_ Review of the literature___________ 2 TiO OS Ge Oe TS alle a are Eee eer 8 
_ General symptoms and macroscopic mumimgy SAE Fi IOUS Mi 13 
Bppenvetiee es Sree or bil yy Him ihiteragure Gitedy2_ C217, 2arsiy to 15 
INTRODUCTION. 


Various writers have shown that an abnormal or pathologic 
parenchyma tissue may occur as an interruption of the normal course 
of the wood elements in the growth rings of coniferous trees, result- 
ing from a variety of widely different causes, which may either 
directly or indirectly influence the growth of the cambium. Among 
these causes may be enumerated mechanical injuries of any kind; 
attacks by various cryptogamic and phanerogamic parasites which 
stimulate the woody tissue to an abnormal development; abnormal 
physiological conditions of growth and nutrition which per se pro- 
duce a like effect ; premature defoliation ; and injuries resulting from 
such meteorological causes as lightning, frost, and drought. The 
last-mentioned three forms of inj ury have rather distinctive anatomi- 
cal characteristics which are scarcely recognized in this country 
and additional knowledge of these is highly desirable. 

Owing to its close resemblance to the disturbances in the wood 
caused by certain forms of lightning injury which he was studying, 
the writer was impelled to investigate also the pathological anatomy | 
of late-frost injury. The present bulletin is therefore designed as 
a contribution to our knowledge of the pathological anatomy of late- 
_ frost injury in the conifers. 

The material used as a basis of this study was collected by the 
writer in connection with his field work in various parts of northern 
Idaho, northeastern Washington, and northwestern Montana and 
_ was supplemented by material collected later in the District of 
Columbia and in Missouri. The photomicrographs were made by 
the writer from his own sectional preparations. 

16168—22—_1 


2 BULLETIN 1181, U. S. DEPARTMENT OF AGRICULTURE. 
REVIEW OF THE LITERATURE. 


Despite the great mass of literature on the subject of frost injury, 
there are but few descriptions of the pathological effect of the 
injury on the structure of the wood. In fact, the effect on forest 
growth of temperatures below the freezing point, or frost, is seldom 
considered, except in so far as it causes injuries the external mani- 
festations of which are readily apparent. 

The so-called frost rings, or “ moon rings,” as they sometimes are 
called when extending only a part of the way around the stem, 
occurring in young trees as a result of the action of frost, have 
been mentioned by various European writers, but it is only rarely 
that their structure and origin have been studied from the stand- 
point of their pathological anatomy, and illustrations of this abnor- 
mality are rare. , 

Mayr (4, p. 36)! states that the stimulating action of a mild late 
frost on the annual ring already in a state of cambial activity exerts 
itself in such a way that in place of the elongated tracheids a short- 
celled parenchyma arises. According to Mayr (5, p. 37), this 
abnormal wood may occur either on only one side of the stem or 
extend entirely around it, depending upon the way in which the cold 
air strikes the plant. In either case internal healing ensues, pro- 
ceeding from the parenchyma cells of the wood, which fill up pos- 
sible cavities with wound parenchyma, while a new cambium is 
developed in the bark from the bast parenchyma remaining alive. 
In addition, Mayr states that if the frost has killed the bast together 
with the cambial layer, then the entire plant part dies. | 

Hartig (2) investigated the action of a May frost on the shoots 
of young trees of Pinus sylvestris. He describes in detail the for- 
mation of zones of parenchyma tissue, which constitute the so-called 
frost ring, in the growth ring developing during the year of the 
injury. He likewise describes the peculiar permanent distortion 
of the injured young shoots, a circumstance occasioned by their loss 
of turgor and consequent drooping after the freezing, followed by 
an effort to redirect their shoots upward. In many cases, however, 
the whorls of shoots were killed outright. 

Hartig also investigated the formation of similar frost rings in 
young trees of Picea excelsa, Larix europaea, and Chamaecyparis 
lawsoniana, but he illustrates their formation only in Pinus syl- 
_ westris and Picea eacelsa. He states that frost-ring formation was 
so frequent in a spruce 2 meters high that he counted 10 frost rings 
in a section about 15 years old, so that 25 rings were to be counted 
in a casual macroscopic examination. The frost-ring formation ex- 
tended down into the stem parts, which were 10 to 12 years old. In 
the larch the frost rings occurred only in its youth, as in the spruce, 
and were found only in the youngest to the 4-year-old axes; in the ~ 
Lawson cypress, however, frost rings still occurred in the older axial 
parts, and such ring formation was noted also in the interior of the 
phloem. Hartig gives the same account later in his textbook of plant 
diseases (3). 


ate Tag numbers (italic) in parentheses refer to “‘ Literature cited” at the end of this 
bulletin. , 


FORMATION OF FROST RINGS IN CONIFERS. a 


Petersen (9) describes and illustrates the zone of parenchyma 
tissue or frost ring which resulted in a double-ring formation in 
beech trees which had suffered from frost on May 17 and 18 in 
Holland. 

Tubeuf (74, pl. 31, fig. 1), in an article upon the pathological 
anatomy of spruce trees that were dying back from the top in 

- consequence of drought injury, evidently for the sake of compari- 
son, illustrates a portion of a frost ring in a small tree of Picea 
; excelsa. However, he makes no allusion in the text to frost injury, 
_ which would seem to be due to his apparent failure to publish the 
_ concluding part of the article. 

- Sorauer, who was able to add the action of frost to the causes 
_ which bring about the formation of false annual rings (72, p. 320), 
_ later gives the details of an extensive study to determine the effects 
of early and late frosts on the mature and immature wood of a 
large number of fruit and forest trees (12). He found that erup- 
_ tions in the vascular cylinder are generally manifested either in 
radial clefts within the medullary rays or in tangential cracks 
_ within the cambial region. In addition, many cavities appear in 
_ the pith and the bark parenchyma. The separated tissue within 
_ the cambium region gradually heals over, after presenting the ap- 
_ pearance of a ring growth of two years. Sorauer discusses the for- 
_ mation of double rings from the activity of frost and gives the 
- same account of this in the last edition of his manual of plant 
_ diseases (12) as well as a detailed account of the injurious action of 
_ frost injury in general upon plant tissue. Here (p. 577) he describes 
_ the brown circular zones, or “ frost lines,” frequently occurring in 
_ fruit trees after spring frosts and composed of collapsed, misshapen 
cells. The occurrence of this phenomenon was also investigated 
_ experimentally in artificial freezing experiments. 

Graebner (/), who investigated the action of late frosts on oak, 
_ beech, spruce, and fir, makes no mention of frost-ring formation 
_as such, but does mention a wound-parenchyma formation that can 
_be followed back into the 2-year-old and 3-year-old wood. 

Neger (7) investigated a tip blight of Picea excelsa with which 
two ascomycetous fungi were associated; however, they were found 
only on shoots that had been injured by frost. Sections of the 
stems, taken both through the dead tips and through the still living 
stems, showed a more or less broad zone of parenchyma wood or 
_ frost ring occurring in the beginning of the 1913 growth ring. 
_ Since this parenchyma zone followed immediately upon the summer 
_ wood of the 1912 growth ring and was not preceded by normal 
_ spring-wood tracheids, it was assumed that a late frost was not in- 
_ volved, but rather an early frost occurring in the fall of 1912. While 
_the frost of 1912 did not come particularly early, relatively low tem- 
_ peratures occurred in comparison with other years, following upon 
a cold wet summer, which greatly retarded the maturation of the 
axial growth of that year. This injury therefore was considered to 
_ be more nearly due to the action of the winter frost upon immature 
wood. Tubeuf (75) had previously briefly described and illustrated 
a tip blight of Picea excelsa due to the same causes, but he does 
not go into the pathological anatomy of the injured shoots. Accord- 
ing to Neger, the frost injury had the effect of suspending or at least 


4 BULLETIN 1181, U. S. DEPARTMENT OF AGRICULTURE. 


reducing the bark pressure, with the result that a zone of paren- 
chyma wood was developed as the first growth in the following 
spring instead of the normal tracheidal wood, in so far as the stem 
had remained living and continued its annual ring formation. In 
his textbook, which appeared later, Neger (8) briefly describes frost 
rings and reproduces an illustration of one caused by this winter 
rost. 

Somerville (77) describes an abnormal zone of parenchyma tissue 
that is very closely related to frost rings, 1f not actually identical 
with them. ‘This abnormal zone occurred in the early-spring wood 
of a large percentage of young conifers whose wood he had occa- 
sion to examine. All of the species examined, including Laria lepto- 
lepis, Pseudotsuga douglasu (=P. taxifolia), Tsuga albertiana 
(=T. mertensiana), Cedrus deodara, Thuja plicata, and Picea 
sitchensis, exhibited more or less of the injury. 

Somerville describes the abnormal wood formation only for Laria 
leptolepis. He says that the abnormal wood formed in the early 
part of 1912 is easily distinguished by the naked eye. On a cross 
section it appears as a narrow brown ring, while on a radial section — 
it forms a thin brown streak. A microscopic examination shows 
that the medullary rays are seen to pursue a most irregular course 
and to consist of much elongated and swollen cells. The rays fre- 
quently are discontinuous with those of the previous ring. The in- 
tervening cells, many of which have walls much thickened, instead 
of getting smaller as one proceeds outward, have a tendency to be- 
come larger. A radial section along the junction of the normal 
summer wood and the abnormal spring wood of 1912 shows that 
the abnormal zone of tissue is largely composed of irregularly 
shaped parenchymatous cells with simple pits and rectangular trans- 
verse walls. It will thus be seen that the foregoing description of 
Someryille’s abnormal wood formation agrees closely with Neger’s © 
description of frost rings, especially since they occur following im- 
mediately upon the summer wood of the preceding growth ring. 

Somerville, however, states that the cause would appear to be the 
excessive heat and drought of the summer and fall of 1911, which 
seriously affected the growth of many trees, notably the Japanese 
larch. He says: 

This climatic condition evidently so upset the normal function of the cam- 
bium that when the wood of 1912 came to be formed it was found to deviate 
greatly from the usual type. 

However, from a consideration of Somerville’s description and 
illustrations of the injury, together with the fact that it occurred 
also in the spring wood of other years, the writer is inclined to re- 
gard this injury as the result of frost rather than of drought. This 
view appears to gain credence when it is considered that, inasmuch 
as the drought occurred during the summer of 1911, it would seem 
likely that the injury to the cambium must have occurred in ample 
time to have registered in the latter part of the 1911 ring, whereas 
it did not register until the beginning of the growth ring of the 
following year. | 7 a 

Mix (6) describes and illustrates the formation of a zone of paren- 
chyma wood in apple trees varying in age from 2 to 8 years, follow- — 
ing an injury to the cambium due to freezing while in the dormant 


Tae 


FORMATION OF FROST RINGS IN CONIFERS. 5 


condition. Macroscopically the injury appeared as a brown line 
between two annual rings. A microscopic examination showed that 
the wood first formed in the spring following the injury was a com- 
paratively narrow zone of parenchyma wood, that the normal xylem 
was soon laid down outside of this zone, and that the remainder of 
the growth ring was normal. The medullary rays, which had be- 
come enlarged and spread out tangentially, could be traced into this 
parenchyma zone. Mention is made of a yellowish brown amorphous 
substance occurring in the intercellular spaces. While Mix was un- 
able to definitely determine the exact nature of this substance, the 
writer, from his investigation of this group of substances (10), 
would regard the brown color as a sign of humification and the 
brown substance itself as a huminlike compound originating as a de- 
composition product of the cell contents of the cells killed by frost. 
The type of frost injury which Mix described is closely related to 
that described by Neger (7) in Picea eaxcelsa. 


GENERAL SYMPTOMS AND MACROSCOPIC APPEARANCE. 


During the field season of 1921 the writer repeatedly observed in 
frost localities on cut-over lands in Washington, Idaho, and Mon- 
tana areas of coniferous reproduction on which a large percentage 
of the young trees showed the effect of repeated late frosts, both 
externally and internally. 

In unusually severe cases the young growth had been killed back 
until the trees had developed an abnormally compact bushy form.? 


Such a growth form, which was by no means common in such native 


trees as Thuja plicata, Tsuga heterophylla, Pseudotsuga taaxifolia, 
Larix occidentalis, Picea engelmanni, Abies lasiocarpa, and Tsuga 
mertensiana, was rarely observed in Pinus contorta, P. ponderosa, 
and P. albicaulis.2 It was extremely common, however, in Abzes 
grandis (Pl. 1, A). The greater tendency of young trees of Abies 
grandis to assume this compact bushy form after injury by late frost 
is due to the great readiness with which this species develops com- 
pensatory shoots. Since the recovery of any given species from frost 
injury depends largely upon its ability to retain dormant buds which 
give rise to such compensatory shoots, it should rank very high in 
both Abzes grandis and A. concolor. 

In the cases of less severe injury the trees did not develop any 
particularly compact bushy form and often did not appear unusual 


in any way, yet the same frost rings occurred in the wood, although 


less frequently and perhaps only in the wood increment of but a 
single year. Where such frost rings occurred, however, it could be 
detected upon close examination in practically all cases investigated 
by the writer that the original terminal shoot of the stem in ques- 
tion had been killed back by frost after the initiation of its growth, 
and that in some cases the same had happened one or more times to 
the volunteer shoots. In this connection the writer wishes to state 
that he has never observed in any of the coniferous species studied 


2The writer wishes to make it clear that he does not consider all cases of the broom- 
ing of young conifers to be due to late-frost injury, since this abnormal form of growth 
may be induced by parasitic fungi alone. In the latter case, however, the formation 
of frost rings does not occur within the zones of annual increment. 

’Host names for American species follow the usage in the publications of George B. 
Sudworth, of the United States Forest Service. 


6 BULLETIN 1181, U. S. DEPARTMENT OF AGRICULTURE. 


by him any pronounced permanent distortion of the living shoots 
which would indicate injury by late frost, except in the case of 
Pinus densiflora Sieb. and Zucc., a Japanese species which will be 
considered later. 

In every case where the terminal growth had been killed, a narrow 
brownish zone of abnormal tissue, or frost ring, could be traced from 
the base of the dead shoot down the stem for a distance of several 
inches, or often for several feet in the case of saplings. This zone of 
abnormal tissue, which has the appearance of a brownish stripe in 
sections of the stem, usually occurred in the immediate beginning of 
the growth ring or else a short distance beyond the outer limit of the 
growth ring of the preceding year. In the latter case it gave the ap- 
pearance of a double ring formation, especially when the growth rings 
were rather narrow. As a rule, the action of late frost manifests 
itself in a closed ring, although occasionally the zone of injury ap- 
pears only on one side of the stem. In no case of late-frost injury 
observed by the writer was any external sign of mechanical injury to 
the bark visible. 

Measurements of the linear extent of the frost rings were made 
in only a few instances where larger trees were involved, since this 
point was not deemed of any particular importance. In general, it 
may be said that in the smaller trees they usually extend down to 
or nearly to the ground line. In the larger trees, however, they 
terminate rather abruptly as the older and therefore better protected 
portion of the stem is reached. While the writer has observed the 
occurrence of frost rings in the outer growth rings of saplings of 
Larix occidentalis and Pseudotsuga taxifolia 2 inches in diameter, 
he has not observed their occurrence in coniferous stems of larger 
size at the time of the injury. Frost-ring formation, however, often 
occurs in larger stems of fruit trees that are subject to various forms 
of frost injury. The latter in general, however, perhaps due in part 
to the cultural practices employed, are more susceptible to frost injury 
than the coniferous trees. Detailed stem-analysis data are recorded 
for four saplings of Larix occidentalis from an area in which.frost 
rings were found to be especially numerous, as mentioned below. 


Stem ANALYSIS OF LARIx OCCIDENTALIS SAPLINGS WITH Frost Rines, Cur At 
IoNE, WASH., AUGUST 24, 1920. 


Tree No. 1.—The tip of the original leader formed in 1918 had been killed and 
was dead down to an elevation of 223 centimeters above the ground, at which 
point a 2-year-old volunteer had developed subsequent to the injury, giving the: 
sapling a total height of 278 centimeters. A conspicuous brownish zone of 
parenchyma wood, located in the 1919 growth ring and developed very soon 
after the initiation of the growth of that year (Pl. II, C), could be traced down 
the stem to an elevation of 65 centimeters above the ground, at which point it 
was no longer apparent under a hand lens. A section of the wood at this point 
showed under the microscope practically no distortion of the wood elements. 

Tree No. 2.—Another sapling, with a height of 865 centimeters and with no 
evidence of any external injury or dead terminal shoot, showed upon dissection a 
similar brownish zone of parenchyma formed shortly after the beginning of 
the 1919 growth ring. This line of parenchyma could be traced from the apex 
of the 1918 growth, at an elevation of 300 centimeters, down the stem to an 
elevation of 175 centimeters, below which point it was no longer in evidence. 

Tree No. 3.—In this case the original leader had been killed, and a volunteer 
leader 2 years old had been put out at a height of 158 centimeters, just below 
the dead tip of the 1918 growth. A brownish zone of parenchyma, formed 
shortly after the beginning of the 1919 growth ring, was traceable down the stem 


FORMATION OF FROST RINGS IN CONIFERS. 7 


directly from the base of the volunteer leader, at an elevation of 158 centi- 
meters to an elevation of 30 centimeters above the ground. In these first three 
trees there was no evidence of any frost injury in the growth rings of any year 
other than those enumerated. 

Tree No. 4.—The original leader of this sapling had been killed, and a 2-year- 
old volunteer had been established at a height of 287 centimeters just below 
the dead tip of the 1918 growth, giving the tree a height of 300 centimeters. A 
conspicuous brownish zone of parenchyma, developed shortly after the beginning 
of the 1919 growth ring, could be traced from the apex of the growth of this 
year, at the base of the dead 1918 tip, at an elevation of 237 centimeters, down 
the stem to an elevation of 75 centimeters. At this point a faint zone of 
parenchyma also showed in the beginning of the 1918 growth ring and could be 
traced up the stem to an elevation of 200 centimeters, a point just below the apex 
of the 1918 growth, where the stem had a diameter of but 2 millimeters. Beyond 
this point the injury was not evident with a hand lens, but only in sections ex- 
amined under the microscope. By means of a microscopic examination this zone 
of parenchyma formation could be traced up to an elevation of 211 centimeters, 
at which point the stem, consisting of only the 1918 growth, was but 1 millimeter 
in diameter, or practically to the apex of the growth ring of that year. 

Through the kindness of J. A. Larsen, director of the Priest 
River Experiment Station in Idaho, the writer was enabled to 
examine and procure material for the study of a number of non- 
indigenous conifers that showed the effects of repeated late-frost 
injury. The trees had been grown to the transplant stage in Cali- 
fornia and planted some years previously on an open bench at the 
experiment station. The stock in question comprised young trees 
of Pinus lambertiana, Pseudotsuga taxifolia, Chamaecyparis law- 
soniana, and Sequoia washingtoniana, all of which except Pseudo- 
tsuga tawifolia are nonindigenous to Idaho. All of these trees, 
especially the two species mentioned last, exhibited an abnormally 
compact and bushy form and owing to the repeated injury con- 
tained frost rings in practically every growth ring. At the time of 
the examination all of the two species last mentioned, as well as a 
large number of the first two species, were dead, due probably to 
the combined action of the repeated late-frost injury and recent 
drought injury. 

The young shoots, however, are by no means always killed back 
by late frost. Not infrequently the shoots injured by frost may 
remain alive throughout and still record the injury within their 
tissues in the usual manner. In this form of late-frost injury the 
terminal shoots as well as the corresponding lateral shoots sometimes 
exhibit more or less of a characteristic permanent distortion, which 
is accompanied by a frost-ring formation in the wood. While not 
observed in any of the western frost-injured conifers which the 
writer studied, this type of injury has been described by Hartig 
(2) for Pius sylvestris and has been observed by the writer in a 
row of young trees of Pinus densiflora, a Japanese species of dwarf 
bushy pine grown in a nursery on the Mall, in Washington, D. C. 
For the correlation of this form of injury with late frost and the 
observations on the behavior of the trees immediately after the 
a the writer is indebted to R. H. Colley and G. F. Gravatt, 
of the Office of Investigations in Forest Pathology. 

From March 27 to 29, 1921, there occurred a general cold wave, 
coming after a period of abnormally warm weather, which was very 
destructive to the active vegetation over a large part of the country 
east of the Mississippi River. On the day following this freeze, 
March 30, it was observed that large numbers of the 1921 shoots 


8 BULLETIN 1131, U. S. DEPARTMENT OF AGRICULTURE. 


along this entire row of Pinus densiflora trees, which was the outer- 
most row on one side of the nursery, had wilted and drooped, due 
to loss of turgor. On a row of trees of Taxus baccata near by in 
the same nursery it was observed that a large number of the new 
shoots, which averaged half an inch in length, were killed outright. 

On September 30 the writer had the opportunity to observe these 
trees. The entire row of Pinus densiflora trees showed numerous 
cases of permanent deformation of the terminal and many of the 
lateral shoots of the last whorl, but all had remained living and 
had regained to a large extent their normal erect position, although 
not without leaving more or less of an S-shaped kink in their stems 
(Pl. IIL). In all cases which the writer examined, such shoots ex- 
hibited a frost ring in the beginning of the 1921 growth ring, which 
could be traced readily down the stem for several inches from the 
base of the last whorl, although it was scarcely to be distinguished. 
even with a hand lens, from the outer limit of the 1920 growth ring, 
owing to its close coincidence (Pl. IV, A). The frost ring like- 
wise was traceable macroscopically on sections cut with a keen micro- 
tome knife, though better microscopically, for a distance of several 
centimeters above the bases of the deformed eterminal and lateral 
shoots of the last whorl, where it appeared in the first wood elements 
bordering upon the pith and in the outer cells of the pith. It was 
lacking in those few lateral branches of the last whorl that some- 
times escaped injury by reason of their lack of development at the 
time of the freeze. In the far less numerous cases of frost injury 
in Taxus baccata, however, there was no evidence of any deforma- 
tion of the young shoots, such as occurred in Pinus densiflora, but 
the young terminal shoots were killed outright and replaced by one 
or more volunteer shoots. In all such cases, where the terminal 
shoot had been killed by late frost, a frost ring could be traced down 
the stem for several inches below the base of the dead terminal shoot 
in the beginning of the 1921 growth ring. . 

A row of trees of Pinus montana var. wncinata, a more hardy ap- 
pearing species planted next to the row of Pinus densiflora, showed 
no single external symptoms of frost injury, and none of the shoots 
which the writer cut into showed any frost rings. On the other hand, 
with the exception of the two species mentioned, there was no evidence 
of any deformation or killing of the shoots by frost on any of the 
other conifers, of which a large variety were in the nursery. 


ANATOMICAL STRUCTURE OF THE FROST RINGS. 


As is well known, when living plant tissue is frozen the water is 
withdrawn from the cells, solidifying to ice in the intercellular spaces 
or other tissue gaps. Upon the initiation of the freezing the water 
from the still living cambial wood passes out between the wood and 
the bark and forms an ice mantle there. The extraordinarily tender 
nature of the youngest cambial cells favors the separation of the 
tissue, and a loosening of the phloem is facilitated either by the 
stronger shrinkage of the frozen wood or by the expansion of the 
cortex due to the stress exerted by the ice formation beneath it. The 
lower the temperature falls the thicker the ice mantle becomes, and 
it compresses the tender cambial cells until their outlines are more 
or less indistinguishable, as is to be seen in Plate IV, A, B, and C. 


Bul. 1131, U. S. Dept. of Agriculture. 


PLATE [. 


FROST INJURY TO ABIES GRANDIS AND TSUGA HETEROPHYLLA. 


fa branch of a similar 


ion 0 
(X10.) 


sult of the ready development of numer- 


fter the first one. 


.) B.—Transverse sect 
th ring a 


, in every grow 


(One-fifth natural size 


compact and bushy form of growth as are 


h 


y every growth ring. 
irely around the stem 


ll 
lly or ent 


1¢a, 
1a 


t 


, Showing the abnormall 
ther part 


ings in prac 
ion, ei 


d by late frosts 


ted frost r 


i 


y injure 
ib 


This tree e 


tree of Tsuga heterophylla, showing frost-ring format 


A —Young tree of Abies grandis repeated] 
ous compensatory shoots. 


“Bul. 1131, U. S. Dept. of Agriculture. PLATE II. 


eS 


mn? Rd ’ » 4 

eid 

cd LF” ‘i 

| es a“ le 
KGa 


N 
ze 
ky 


WEAWs (95 Sa 


giagae 


FROST INJURY TO THUJA PLICATA, PSEUDOTSUGA TAXIFOLIA, AND LARIX 
OCCIDENTALIS. 


A.—Transverse section through frost ring in Thuja plicata, showing a pronounced distortion of 
the medullary rays. (<135.) B.—Transverse section through frost ringin Pseudotsuga taxifolia, 
showing the crumpling of the wood cells that were but slightly lignified at the time of freezing. 
(X135.) C.—Transverse section through frost ringin Larix occidentalis sapling (tree No.1), at 
146 centimeters above the ground, showing an extreme case of lateral displacement of the 


medullary rays. (X185.) 


Bul. 1131, U. S. Dept. of Agriculture. PLATE III. 


we 


w-) oe 


‘ 


FROST INJURY TO PINUS DENSIFLORA. 


Effect upon Pinus densiflora of alate March frost occurring after the development of many of the 1921 
shoots had been initiated, showing the characteristic permanent distortion of the terminal shoot 
and three of the five lateral shoots. Photographed September 30. (Two-thirds natural size.) 


Bul. 1131, U. S. Dept. of Agriculture. PLATE IV. 


ry 
% 


a 


Ne 


oe 
gus 


wtf 
@ 
al i 


iy 


ita 6 ee 
? a é 
Cd 


FROST RINGS OF PINUS DENSIFLORA, ABIES GRANDIS, AND TSUGA HETERO- 
PHYLLA. 


A —Transverse section of stem of Pinus densiflora taken 10 centimeters below the 1921 whorl of 
branches, showing a slight frost ring formationin the 1921 growth. (X135.) B.—Transverse 
section of Abies grandis, showing a more pronounced frost-ring formation, with the character- 
istic lateral displacement of the medullary rays and their proliferation. (X135.) C.—Trans- 


verse section through a frost-ring formation in Tsuga heterophylla, showing the formation of 
a broad zone of parenchyma wood ( X135.) 


Bul. 1131, U. S. Dept. of Agriculture. PLATE V. 


BINS ws “ | 
p TS, se , , 
ge * 
, F 
TT 


ery 
eae 


{ 


ae: 
: aicqes ee’ 


Va 


gr? 


one WN 
ae 


gee Si ern 


ar 


i sn 
.@. 


“8 
Sl 


a, 


ex 


Oe &. rf - 4% 
> Pe SOMES MAK 
: SY. MOS yn, IIo me 
bat iD & te ‘eas =. = 
4} - ete higte) alive 
aa? d= 28e 
@ ‘o@ | 9@, a8 


FROST INJURY TO PINUS MONTICOLA AND PINUS ALBICAULIS. 


A .—Transverse section through a stem of Pinus monticola, showing the termination of the pre- 
ceding annual ring (at the outer margin of the resin canal at bottom of picture) and three frost 
rings occurring in the early portion of the succeeding growthring. (X135.) B.—Transverse 
section through a frost ring in Pinus albicaulis, showing the crumpling of the wood cells that 
were but slightly lignified at the time of freezing and the formation of a radial cleft (at the left) 
which has become filled by large-celled parenchyma. ( 135.) 


PLATE VI. 


Bul. 1131, U. S. Dept. of Agriculture. 


: sl de ‘e oe’ 
Ae } 4 
=o Sorsze 
Pt _ 
’ 
$f 


eee rey 
Tr 17 


we 


* 


Pd. Pag “RS... BC p, Sito-, 


Seevae ®> SI =e ne 
B > = 4 tee 4 Se | 5 
a &. - 


% 


® 


ho SO ee. ge we 
— Pg pied, 9 Oe @ 


#8 .,. : 
aaazel éaite se: Seas " as 


PTT" ee 


CHAMAECYPARIS LAWSONIANA, AND 


SEQUOIA WASHINGTONIANA. 


FROST INJURY TO TSUGA MERTENSIANA 


ma 
g occurring 


parenchyma. 
showing a series of 


ped before the 


celled 
brown parenchy 
st rin 


e outer face of a pre- 
Fro 


showing th 
fied tracheids develu 
hand corner) filled up with large- 
dian position in a growth 
(X135.) C— 
oniana, 
(X<185.) 


quoia washing! 


radial clefts subsequently filled up with large-celled parenchyma. 


, 


na 
number of well-ligni 
ying a me 
gan unusually broad zone of dark- 
celled parenchyma. 
n in Se 


gin Tsuga mertensia 
gh a frost ring occup 


5) 


filled up with large- 


is lawsoniana, showin 
at the outer limit of a summer-wood formatio 


—— Transverse section throu 


hamaecypar 


also a radial cleft (at upper left 
and radial clefts also 


owth ring at bottom and a large 


B 


Transverse section through frost rin 


ceding gr 
freezing; 
(<185,) 

ring of C 


Jj) = 


eS EES 


FORMATION OF FROST RINGS IN CONIFERS. 9 


The already thick-walled but still unlignified cells collapse also, 
their walls presenting a crumpled appearance (PI. II, 2, Pl. V, B). 

After the thawing, the cell tissue that has been compressed does 
not expand to its previous form and size, but remains permanently 
distorted. In the cases of the more severe injury there begins at the 
periphery of the wood formed before the injury a more or less broad 
zone of large-celled parenchyma, which is distinguished by its 
greatly thickened simple-pitted walls and by the dark-brown color 
of the walls and the cell contents. This zone of parenchyma tissue 
quickly passes over into tracheidal tissue, which at first is usually 
somewhat larger celled than that developed before the frost injury, 
but which quickly becomes typical. In this manner the frost injury 
resul:s in the formation of a false ring, especially if it occurs after the 
development of several spring-wood tracheids (Pl, IV, B; Pl. V, 
Avge Vis Acand 2). 

As may be seen from.the accompanying reproductions of photo- 
micrographs, the frost rings exhibit great dissimilarity in structure, 
according to the degree of intensity of the frost action and the sus- 
ceptibility of the wood tissue at the time of its occurrence. | 

he medullary rays, which extend through the frost ring and 
stretch in accordance with the stress exerted upon them, naturally 
suffer most from the displacement of the tissue. Their deformation 
varies according to the severity of the injury, but in general is 
very characteristic. On the inner side of the frost ring the rays 
widen out abruptly, often becoming 2-seriate or 3-seriate instead of 
uniseriate (PI. IV, 8; Pl. Il, B). The rays apparently are stimu- 
lated to lateral broadening by the diminution of the pressure nor- 
mally exerted by the adjoining wood elements, caused by the crush- 
ing together of the young wood elements. This broadening ensues 
immediately in the region of the frozen young wood and reaches 
its greatest extent within the region which, in the frozen condition, 
was filled by ice. In addition to broadening out laterally, the rays 
usually are also more or less sharply displaced, often undergoing 


a knee-shaped bending (Pl. IT, A and @). Within any one stem 


the medullary rays are usually, although by no means always, dis- 
placed uniformly either to the one side or to the other. As the wood 
ring enlarges after the thawing, the medullary rays are brought 
into an oblique position and later grow out again in their original 
direction, continuing in equal number in the newly formed wood 
and causing the wood tissue to appear as though a fault had oc- 
curred in it. The lateral displacement of the medullary rays appar- 
ently depends upon the circumstance that their stretching during 
the ice formation remains preserved after the thawing. This lateral 
expansion and displacement of the medullary rays is by far the 
most conspicuous and characteristic feature of late-frost injury and 
is a constant feature of all injuries to wood by late frost. In at 
least the more severe cases of injury the frost ring is further accentu- 


B® sted by a more or less broad zone of brownish parenchyma tissue. 


There also may arise after the thawing a series of radial gaps 
or clefts, SeeUT ENS with variable frequency and conspicuousness 


within the tracheidal tissue, where it had been stretched apart pre- 


viously by the excessive tangential contraction. With subsequent 
growth, these tissue gaps become filled with large-celled parenchyma 


\ 
10 BULLETIN 1131, U. S. DEPARTMENT OF AGRICULTURE. 


derived from the new cambial formation (Pl. V, B; Pl. VI, Band 
(.) An unusually striking example of this radial cleft formation 
occurred in the frost rings observed in stems of Sequoia washing- 
toniana, where clefts were present not only in the early formed — 
portion of the growth ring but also at the outer limit of the summer- — 
wood formation (Pl. VI, C). In the latter case the frost rings ap- 
peared to lie between the summer wood of one growth ring and the 
spring wood of the next, so that there was no sharp demarcation 
between the two annual rings except where the frost ring did not 
extend completely around the stem. Still other stems from the 
same material, which had been injured by frost near the close of 
the growing season and had died without subsequent growth, ex- — 
hibited the same radial clefts at the periphery of the xylem, but 
in this case the clefts were still open and free from any occlusion — 
by parenchyma cells. Such tissue disturbances result in a very pro- 
nounced false ring formation. 

A large part of the phenomena which come to light in frost injuries 
to young stems, however they may vary, can be traced to simple 
mechanical processes. Sorauer (12) has proved experimentally that 
processes of loosening are initiated in the cell membranes by the 
action of frost; and this explains the formation of this parenchyma 
zone instead of the normal wood elements as the result of a weaken- 
ing of the compressing influence exerted by the bark girdle on the 
youngest tissue, that is, the cambium. According to Sorauer, the 
frost, without necessarily forming ice crystals in the intercellular 
spaces, contracts the tissue in direct proportion to the thinness of 
the walls of the tissue. The bark suffers considerably more than — 
the wood, which, reached later, cools down less easily and contracts 
less. The tangential contraction is greater than the radial. As 
Sorauer states, this difference acts like a one-sided strain and exerts 
itself in the direction of the circumference of the trunk, to which — 
the different layers of the bark will respond to a different degree 
when the bark as a whole is very young. Consequently, with the 
action of the frost there must take place everywhere within a woody 
axis a preponderance of tangential strain over radial contraction, 
and under certain circumstances this must increase to a radial split- 
ting of the tissue. With an equal degree of contraction at all points 
in the bark, the cells lying nearest the periphery and most elongated 
in the direction of the circumference of the trunk will be the most 
displaced. As Sorauer also states, if one considers that the outer 
cells of the primary bark, because of the greater coarseness of their 
walls, are not as elastic as the underlying thinner walled ones, it is 
clear that when the strain ceases in them the permanent stretching, 
caused by the incomplete elasticity, will be the greatest there. After 
the action of the frost, which continues but a short time in late frosts, 
has stopped, the tissue that has become stretched is not sufficiently 
elastic to contract again to its original volume, and the cells retain 
their distended and distorted form. In this way each frost action 
leaves behind an excessive lengthentng of the peripheral tissue layers — 
in proportion to the adjacent layers which lie more toward the inside. 
The bark body as a whole is therefore larger and either does not 
have room enough on the wood cylinder, so that in places it is raised _ 
up from it, or it at least decreases its constricting influence on the © 


2 LL <= SC CC LULU 
i ok oS AZ! 


FORMATION OF FROST RINGS IN CONIFERS. 11 


cambial elements of the wood cylinder. The cambial zone responds 
to this with the formation of parenchyma wood, as may be seen in 
every wound in which the bark is raised. If the bark girdle closes 
together again into a connected layer the cambial cylinder by growth 
in thickness must again resist the constricting effect of the bark and 
on this account again forms normal wood elements. 

In sections containing frost rings that when viewed macroscopi- 
cally appear to be only one-sided, it can be recognized in a microscopic 
examination that, as a rule, a lesser disturbance has occurred on the 
other side of the stem (PI. Il, B). However, a disturbance of the 
wood tissue by no means always extends entirely around the stem, 
the'same often being purely local and consisting of numerous isolated 
groups of parenchyma elements. The frost rings occasioned by late 
frost vary greatly in their position within the growth ring, but usu- 
ally occur early in the spring wood, either in the immediate beginning 
or after the formation of a few normal tracheids. On the other hand, 
they may not be formed until late in the growth ring when the frost 
must necessarily occur during the summer. Frost rings in the latter 
position are comparatively rare, however. 

More than one frost ring may occur within the wood of any one 
growth ring, depending upon whether or not the frost occurs more 
than once after the spring growth has been initiated. Two frost 
rings within one annual ring are fairly common, and the writer has 
observed the occurrence of three frost rings in the spring-wood zone 
of an annual ring in Pinus monticola (Pl. V, A) and in Picea 
engelmanne. 

Frost-ring formation may occur in the wood from the action of 
either late or early frosts during the course of the growing season 
or from the freezing of the cambium during the winter when the 
tree is dormant. The frost rings, therefore, may register at any 
point within the growth ring, the relative position of the frost ring 
within the growth ring signifying the time at which the injury 
occurred. 

According to Hartig (2, p. 4), frost rings arise through late-frost 
injury only when the cambial activity has already commenced and 
at least some few cells have been cut off toward the interior, if, there- 
fore, the annual ring formation has been initiated. It has been the 
writer’s experience with late-frost injury that, while the number of 
spring-wood tracheids that intervene between the outer limit of the 
summer wood of the preceding annual ring and the frost ring is 
usually fairly uniform on any radius, the frost-rings sometimes ap- 
pear to abut directly on the summer wood of the preceding growth 
ring, although groups of normal spring-wood tracheids usually 1n- 
tervene in places. The formation of at, least some normal spring- 
wood elements would therefore appear to be a diagnostic feature of 
late-frost injury. | 

In the case of late frost occurring unusually late in the season, the 
frost rings may register in the median or outer portion of the growth 
ring (Pl. VI, B). In the case of early frosts occurring late in the 
season, at a time when the annual accretion of wood has not matured, 
or in the case of frost injury occurring during the dormant period of 
the year, the resulting frost ring registers in the immediate begin- 
ning of the next growth ring, often tending to obscure the normally 
sharp demarcation between the two rings (Pl. VI, @). 


12 BULLETIN 1131, U. S. DEPARTMENT OF AGRICULTURE. — 


In general, it appears that frost injury occurring shortly after the 
initiation of active growth causes a greater distortion of the wood 
elements than that occurring when the growth ring is practically 
mature or when the tree is dormant. 

Frost rings are often confusing to those who have occasion to 
engage in age determinations or stem analyses of trees. The frost- 
ring formation, however, usually occurs within such close limits of 
the beginning of the annual ring formation that, macroscopically at 
least, the parenchyma zone appears to coincide more or less closely 
with the outer limit of the preceding growth ring. Frost-ring 
formation should prove confusing in age counts only when it occurs 
late in the season after a considerable portion of the growth ring 
has been formed. Moreover, since only the younger stems appear 
to be susceptible to frost-ring formation, it is believed that in coni- 
fers at least, false ring formation from this source need be expected 
ely only in the first several growth rings formed in the life of 
the tree. 

As may be expected from their structure, frost rings constitute 
a plane of weakness in the wood, since there is no strong bond be- 
tween the wood formed before the injury and the parenchyma wood 
formed immediately after it. In chopping off a face on stems con- 
taining one or more frost rings in order to follow their linear 
extent, the wood frequently splits peripherally along the plane of 
these zones of abnormal wood. In future years it seems likely, as 
Somerville (77) states for the abnormality which he describes, that 
they may lead to the formation of ring shakes within the trees. 

The writer’s investigation of the pathological anatomy of late- 
frost injury confirms those of Mayr, Hartig, and Sorauer in all par- 
ticulars except the occurrence of the chains of pathologic resin 
canals, which Mayr (4) suggests may be caused by frost and which 
Hartig (2) found sometimes associated with the frost rings. ; 

Mayr (4, p. 29), in a discussion of the chains of abnormal or 
pathologic resin canals sometimes found in the wood of Abzes firma 
and Tsuga, suggests that they may be caused by late frost, which, he 
states, is of fairly common occurrence. However, he observed that 
such chains of resin canals may also be found in the hard summer- 
wood zone of the annual ring, where late frost is excluded as’a 
cause. Although not considered by Mayr, a number of other types 
of injury could easily have been responsible for this pathologic 
resin-canal formation. | 

Hartig (2, p. 7) states that he has repeatedly found that the woun 
parenchyma developing in the frost ring contained resin canals, so 
that a more or less complete ring of them was recognizable in the 
frost zone. Despite the writer’s particular consideration -of this 
point and his extensive investigations on pathologic resin-canal 
formation in general, which will appear shortly, he has never ob- 
served the formation of chains of pathologic resin canals as the 
result of frost injury. While zones of pathologic resin canals do 
occasionally coincide with the frost rings in a stem, the writer has 
always traced their origin to some mechanical wound. It is by no 
means impossible, however, for such zones of pathologic resin canals 
to arise schizogenously within the broad aggregates of parenchyma 
wood comprising the frost ring. 


— OU 


= 


FORMATION OF FROST RINGS IN CONIFERS. 13 


Hartig (2, p. 7) likewise mentions the occurrence of chains of 
abnormal resin canals, which he regards as due to the action of late 
frost, throughout the entire circumference of the phloem of stems of 
Chamaecyparis lawsoniana 2 centimeters thick, at a slight distance 
from the cambial layer. He states that these arise by the medullary 
rays stretching and becoming broadened laterally through cell divi- 
sion and that between each two rays the delicate-walled tissue com- 
posed of sieve tubes and parenchyma was crowded apart. He as- 
sumes that here also the tissue gaps are not closed after the thawing 
of the ice, and finds that the surrounding living cells become en- 
larged more or less into these gaps and become converted into resin- 
secreting cells, pouring large quantities of resin into them. As a 
result of this formation a festoon of large resin beads appears from 
the bark on the ends of cut-off shoots. The writer, however, did 
not observe any formation of chains of pathologic resin canals in 
the phloem of the frost-injured material of Chamaecyparis law- 
sonzana studied by him. 


SUMMARY. 


The pathological anatomy of late-frost injury has been studied in 
detail by the writer in Pinus albicaulis, P. contorta, P. densiflora, P. 
lambertiana, P. monticola, P. ponderosa, Picea engelmanni, Larix 
occidentalis, Pseudotsuga taxifolia, Abies grandis, A. lasiocarpa, 
Tsuga heterophylla, T. mertensiana, Thuja plicata, Chamaecy paris 
lawsoniana, Sequoia washingtoniana, and Taxus baccata; also in 
apple and pear trees. 

The young shoots injured by late frost may either wilt through 
‘loss of turgor and after again directing their points upward usually 
become permanently distorted, or, as generally happens, they may be 
killed outright and replaced by one or more volunteer shoots. The 
structural disturbance initiated by the action of late-frost injury is 
not confined to the shoots then developing, but extends down the 
stem for distances varying from several inches to several feet below 
the base of the injured shoots, or as far as the cambium has been in- 
jured by the freezing without entailing the death of the stem. The 
healing proceeds internally and results in the formation of a brown- 
ish zone of parenchyma wood, or frost ring, within the growth ring, 
developing at the time of the injury. 

Late-frost injury results in very characteristic disturbances in the 
tissue of the growth ring forming at the time of the injury. The 
abnormal tissue of the frost ring varies greatly, according to the 
severity of the injury, and may be characterized by various combi- 
nations of such features as the crumpling of the wood cells that were 
but slightly lignified at the time of the injury, a marked broadening 
or proliferation of the medullary rays, a strong lateral displacement 
of the medullary rays together with a marked broadening or pro- 
liferation, the presence of radial clefts subsequently filled up by 
large-celled parenchyma, and more or less broad zones of wound 
parenchyma. The displacement of the medullary rays is occasioned 
by their stretching and lack of elasticity ; the radial clefts, to the pre- 
ponderance of the tangential contraction over the radial contraction ; 
and the interpolated zone of parenchyma wood, to a transitory weak- 
ening of the compressing influence exerted by the bark girdle on the 
cambium, due to the disrupting action caused by the freezing. 


14 BULLETIN 1131, U. S. DEPARTMENT OF AGRICULTURE. 


Frost-ring formation may occur in the wood from the action of 


either late or early frost during the course of the growing season 
or from the freezing of the cambium during the winter when the 
tree is dormant. The frost rings, therefore, may register at any 
point within the growth ring, the relative position of the frost ring 
within the growth ring signifying the time at which the injury 
occurred. . 

Frost rings arise through late frost only when the cambial ac- 
tivity has already commenced and some new xylem cells have been 
differentiated. e: a rule, there is a definite zone of spring-wood 
tracheids intervening between the outer limit of the summer wood 
of the preceding annual ring and the frost ring. In the case of 
early frosts the frost ring may either register late in the summer 
wood of the growth ring or not until the immediate beginning of 
the ensuing growth ring. Frost injury occurring during the dor- 
mant period likewise is recorded as a frost ring in the immediate 
beginning of the ensuing growth ring. } aah 

Young trees injured by repeated frosts often develop an abnor- 
mally compact and bushy form, especially in Abses grandis and 
other species, which readily form compensatory shoots. Frost in- 
jury that results in the killing of the young shoots often detracts 
greatly from the straight axial growth of the trees and, where fre- 
quently repeated, may render the tree absolutely valueless for com- 
mercial purposes. In addition, late-frost injury may render young 
conifers more susceptible to weakly parasitic fungi than they would 
be otherwise. 


Late-frost injury, when occurring late in the season after any — 


considerable portion of the growth ring has been formed, results 
in a false or double ring formation, which is often confusing in 
age determinations. Frost-ring formation from late-frost injury 
has not been observed by the writer in coniferous stems larger than 
2 inches in diameter, although it often occurs in larger stems of 
fruit trees that are subject to various forms of frost injury. ; 

As may be expected from their structure, frost rings constitute 
a plane of weakness in the wood, which may not only predispose 
to the formation of circular shake in the standing tree, but may 
require the manufactured wood to be discriminated against for use 
in small pieces where great strength is required. 


ee 
< 


ee eee 


(1) 


(2) 


(13) 


(14) 


(15) 


LITERATURE CITED. 


GRAEBNER, PAUL. 

1909. Beitriige zur Kenntnis nichtparasitérer Pflanzenkrankheiten an 
forstlichen Gewichsen. 8. Wirkung von Frésten wihrend der 
Vegetationsperiode. Jn Ztschr. Forst. u. Jagdw., Jahrg. 41, Heft 
7, p. 421-431, 5 fig. 


HARTIG, ROBERT. 
1895. Doppelringe als Folge von Spatfrost. Jn Forstl. Naturw. 
Ztschr., Jahrg. 4, Heft 1, p. 1-8, 6 fig., pl. 1. 


1900. Lehrbuch der Pflanzenkrankheiten ... Aufl. 3, ix, 824 p., 
280 fig. Berlin. 


MAyR, HEINRICH. 
1890. Monographie der Abietineen des Japanischen Reiches... 
viii, 104 p., 7 col. pl. Miinchen. 


1894. Das Harz der Nadelhdélzer, seine Entstehung, Vertheilung, Be- 
deutung und Gewinnung. 96 p., 4 fig., 2 col. pl. Berlin. 


Mrx, A. J. 
1916. The formation of parenchyma wood following winter injury to 
the cambium. Jn Phytopathology, v. 6, no. 8, p. 279-283, 3 fig. 


NecGeEr, F. W. 
1916. Ueber eine durch Friihfrost an Nectria cucurbitula Fr. und 
Dermatea eucrita (Karst.) verursachte Gipfeldiirre der Fichte. 
In Naturw. Ztschr. Forst. u. Landw., Jahrg. 14, Heft 3/4, p. 121- 
127, 4 fig. 


1919. Die Krankheiten unserer Waldbiume und wichtigsten Gar- 
tengehdlze ... viii, 286 p., 234 fig. Stuttgart. 


PETERSEN, O. G. 
1905. Nattefrostens he ore paa Bggens Ved. Jn Denmark. Forst- 
lige Forségsvaesen, Bd. 1, p. 49-68, 12 fig. 


RHOADS, ARTHUR S. 
1917. The black zones formed by wood-destroying fungi. Tech. Pub. 
8 (v. 17, no. 28), N. Y. State Coll. Forestry, 61 p. incl. 6 pl. Lit- 
erature cited, p. 46-49. 


SOMERVILLE, WILLIAM. 
1916. Abnormal. wood in conifers. Jn Quart. Jour. Forestry, v. 10, 
no. 2, p. 182-186, 10 fig. on 3 pl. 


SORAUER, PAUL. 

1886-1909. Handbuch der Pflanzenkrankheiten. Theil 1, Die nicht- 
parasitaren Krankheiten. Aufl. 2, xvi, 920 p., 61 fig., 19 pl. Ber- 
lin. 1886. Aufl. 3, xvi, 891 p., 208 fig. Berlin. 1909. Biblio- 
graphical footnotes. 


1906. Experimentelle Studien tiber die mechanischen Wirkungen des 
Frostes bei Obst- und Waldbiumen. Jn Landw. Jahrb., Jahrg. 35, 
Heft 4, p. 469-526, pl. 9-18 (partly col.). 


TUBEUF, CARL VON. 
1906. Pathologische Erscheinungen beim Absterben der Fichten im 
Sommer 1904. In Naturw. Ztschr. Land. u. Forstw., Jahrg. 4, 
Heft 11, p. 449-466, 6 fig., pl. 26-82; Heft 12, p. 511-512. 


1913. Absterben der Gipfeltriebe an Fichten. In Naturw. Ztschr. 
Forst. u. Landw., Jahrg. 11, Heft 8, p. 396-399, 1 fig. 


15 


ORGANIZATION OF THE UNITED STATES DEPARTMENT OF 


AGRICULTURE. 

{ 
Secretary. of., AQTICUNUTE... > + eee Be ~ HENRY C. WALLACE. 
Assistant Secretary se 2) o0 ce C. W. PUGSLEY, : 
Director of Scientific Work ~~~. 2_- E. D. BAtt. : 
Director of Regulatory Worcs <=. "tt , 
Weather Bureau h® +. BOGAN Ly Less CHARLES F, MARVIN, Chief. 
Bureau of Agricultural Economics_____.--__- Henry C. Taytor, Chief. 
Bureau of ,Animatl industry... JOHN R. Mouter, Chief. 
Buréau of Plant Industry _-._---_-__ WILLIAM A. TAYLOR, Chief. 
Forest, Sexrvige + eM 2 a ea ee W. B. GREELEY, Chief. 
Bured Of CHG IAS TTY pe itm ee tte ee eno WALTER G. CAMPBELL, Acting 

Chief. 

IEUS GT: OR: ROGGE is MILTON WHITNEY, Chief. 
Burequs: of Bndomolo Gy 622 a es L. O. Howarp, Chief. 
Bureau of Biological Survey ___.__-.+2..-__. BH. W. NEtson,. Chief. 
Bureau, Of Public ;pROGG8 xctso 06 - a ete t. THoMAS H. MacDonatp, Chief. 
Fived-Nitrogen Research Laboratory___.._-__- F. G. Corrreti, Director, 
Division of Accounts and Disbursements____- A. ZAPPONE, Chief. 
Division of Publications________-__-_______---. JOHN L, Copss, Jr., Chief. 
TROT CY 2 SOI STEEN) _ SUES RS SCA ACSA CLARIBEL R. BARNETT, Librarian. 
States Relations Service______-__-__-______- A. C. TruE, Director. f 
Federal Horticultural Board____-_+---------. C. L. MArtattr, Chairman, 
Insecticide and Fungicide Board____________- J. K. Haywoop, Chairman. 
Packers and Stockyards Administration__—-- \ CHESTER MorRRILL, Assistant - 
Grain Future Trading Act Administration__ to the Secretary. 
Office of} the Soncitots— 42cce08--4b 24242 5) R. W. Witt1AMs, Solicitor. 


This bulletin is a contribution from the— 


Bureau of Plant Industry___—_-_---2U_-2 41-2 WittiAmM A. Taytor, Chief. i 
Investigations in Forest Pathology_----- HAVEN MetTcaLr, Pathologist in 

. Charge. 

16 . 


ADDITIONAL COPIES 
OF THIS PUBLICATION MAY BE PROCURED FROM 
THE SUPERINTENDENT OF DOCUMENTS 
GOVERNMENT PRINTING OFFICE 
_. WASHINGTON, D. C. 
AT 


10 CENTS PER COPY 


PURCHASER AGREES NOT TO RESELL OR DISTRIBUTE THIS 
COPY FOR PROFIT.—PUB. RES. 57, APPROVED MAY 11, 1922 


V 


UNITED STATES DEPARTMENT OF AGRICULTURE 


DEPARTMENT BULLETIN No. 1140 


Washington, D. C. PROFESSIONAL PAPER March 29, 1923 


“THE DETERIORATION OF FELLED WESTERN: YELLOW PINE ON 
INSECT-CONTROL PROJECTS." 


By J. S. Boyce, Pathologist, Office of Investigations in. Forest Pathology, 


\ Bureau oe Plant Industry. 
CONTENTS. 
Page. Page. 
Pmenoemcnons 2 6i2 2) Loe 1 | Causes of deterioration___________ 4 
Method of collecting data__-__-- 2) TCORCINBIONR: 2 oo be ee 6 
Rate of deterioration-___---_--_~- 2 


INTRODUCTION. 


During the past 15 years extensive insect-control measures have 
become necessary in various localities in the western United States 
in order to check epidemics of the western pine beetle (Dendroctonus 
brevicomis Lec.) and the mountain-pine beetle (Dendroctonus mon- 
ticolae Hopk.) on western yellow pine (Pinus ponderosa Laws.), 
lodgepole pine (Pinus contorta Loud.), western white pine (Pinus 
monticola Dougl.), and sugar pine (Pinus lambertiana Dougl.). 
Briefly, control consists in felling and barking the infested trees (or 
burning the bark in the case of Dendroctonus brevicomis), in order 
to destroy the overwintering stages of the beetles. The trees usually 
_ are limbed well into the top but are not cut into log lengths. 

The attacks of the western pine beetle on western yellow pine have 
been widespread, and consequently the most extensive control projects 
have been concentrated on this tree species. At present control work 
is under way in the yellow-pine regions of British Columbia and 
central California, while a large project was begun in the spring of 
1922 in the Klamath Lake region of southern Oregon. 

The southern Oregon-northern California project begun in the 
spring of 1922 necessitated the felling of about 16,000 merchantable 
western yellow pines, with an occasional sugar pine, comprising ap- 


1 This study was made in cooperation with the Klamath Forest Protective Association 
at Klamath Falls, Oreg. Without the yearly records of the association giving the loca- 
tion | of felled trees, the study would have been impossible. The writer is indebted to 
Kimball, secretary-treasurer, and to H. H. Ogle, of the same association, for 
: valuable assistance in obtaining the field data. 


25322—23 ; I 


o™~s 


2 BULLETIN 1140, U. S. DEPARTMENT OF AGRICULTURE. 


proximately 16,000,000 feet board measure, over an area roughly of — 4 


200,000 acres. Further work in the next three or four years will 
probably involve eutting an additional 20,000,000 feet of merchant- 
able timber on adjoining areas. These trees must be left on the 
ground until such time as they can be reached by logging operatiens. 
The rate of deterioration of this felled timber then becomes of para- 
mount importance. It is in connection with this projeet that the 
study reported here was made. i a 


# 


METHOD OF COLLECTING DATA. ee PIs f 


Local control work has been carried on in this region for some — 


years by the Klamath Forest Protective Association, and records 
of this association were available, giving the general location of 
trees felled yearly since 1915. From these records, felled trees were 
relocated and examined during November, 1921. 

Each tree was opened up sufficiently with ax and saw to permit 
scaling in 16-foot logs with the Scribner decimal C seale, aceording 
to standard commercial practice. Logs two-thirds or more unmer- 
chantable by volume were culled. Diameter measurements were 
taken to the nearest inch, and length measurements to the nearest 
tenth of a foot. The gross scale where given is the actual merchant- 
able volume in the trees at the time of felling, determined when this 
study was made. In making the measurements of decay, the subse- 
quent advance of decay present in the living tree at the time of fell- 
ing was disregarded. In the region in which the trees were stud- 
ied the decays in living yellow pine seem to advance very slowly or 
not at all after an infected tree is felled. Characteristically, west- 
ern yellow pine is a sound species, and the normal loss through 
decay in stands of living trees does not exceed 2.5 per cent and may 
be much less. The only two kinds of decay found in the trees ex- 
amined which were there at the time of felling were rots caused by 
the ring-scale fungus (Trametes pini (Thore) Fr.) and brown cu- 
bical butt-rot caused by the velvet-top fungus (Polyporus schwet- 
nitzii Fr.). Two trees had been infected with the first-named rot, 
with a slight loss resulting. Brown cubical butt-ret had also been 
present in two trees, but there was little indication left of the decayed 
wood, which had been almost completely destroyed by fire when the 
bark removed from the trees was burned. 

Data were obtained on a total of 100 trees, all western yellow pine, 
near Bly, Klamath Falls, and Keno, in Klamath County, Oreg., at 
elevations around 6,000 feet above sea level. The site conditions 
were essentially the same for all the localities. These trees varied 
from 16 inches to 43 inches in diameter outside bark at stump height, 
and the usual stump height ranged from 2 to 3 feet. 


RATE OF DETERIORATION. 


These felled trees deteriorate with extreme rapidity, far more 
rapidly than the casual observer is led to believe. The heat from 
burning the bark and from the sun’s rays results in a pronounced 
drying of the outer sapwood to depths averaging one-half inch. 
This outer layer, being too dry to decay, remains hard and sound 
for several years, and if tested superficially leads to the belief that 


———— ee 


DETERIORATION OF WESTERN YELLOW PINE. 3 


- the tree is sound throughout, when as a matter of fact it may be. 
commercially a complete loss through decay. Table 1 shows the 
rate of deterioration. 


TABLE 1.—Rate of deterioration of felled wesiern yellow-pine trees in Klamath 
County, Oreg. 


— 
/ Trees with 
| | Volume (board feet). merchantable | Average 
| Bearer zeal Per- volume. = diameter) Num- 
When cut. éfex. (4 ++| pentage|-——- ila inside ber of 
posure. | | | of cull. bark | trees 
|: / | ee | Num- |. Per | Stump | (basis). 
Gross. Coll. |, Net. Vat ees centage|(inches). 
| * | of total. 
me of hss ee a oa I | ste a ey) a | ee aoe 
1 | 2 ve ai 5 6 aie | 9° | 10 

i | ee a uM 
Mepril, T02T 2: 3... 5. | 1 6, 400 810 5,590 13 6 100 24 6 
December, 1920....... 1 11,350 2,060 9, 290 18 12 100 23 12 
February, 1920....... 2; 11,610 7,360 | 7250 | 11 79 23 14 
November, 1919...... 2 8,080 6,120 1,960) 76 6 75 21 8 
Spring of 1919........ 3 15,870 12,900 2,970 | 81 10 62 16 
Spring of 1918........ 4 2,650 | 1,790 860 68 3 100 23 3 
ro |: |) Ar? 5 35,510 28, 960 6,550 82 7 31 16 
Spring of 1916........ 6 13,270 | 12,060 1,210 | 91 2 14 23 14 
Spring of 1915........ 7 11,470 | 10,710 760 | 93 1 9 25 11 


ae 


In Table 1 the expression “seasons of exposure” means the num- 
ber of growing seasons that have elapsed since the trees were felled. 
It is, of course, during the growing season that the greatest deteriora- 
tion occurs, although loss continues throughout the year. This is 
shown by the fact that the trees cut in April, 1921, and exposed for 
one season show a loss of 13 per cent, while those cut in December, 
1920, also exposed for one season but with four additional months 
in winter and early spring, show a loss of 18 per cent. The same 
relation holds for the trees exposed for two seasons but cut at dif- 
ferent times. 

‘The important feature of Table 1 is the enormous increase in the , 
cull percentage after the first season. This increase is from 13 and 
18 per cent for the first season to 63 and 76 per cent for the second 
season and is so great that from an economic standpoint felled trees 
must be utilized before they pass into the second season of exposure. 
This means that the bulk of the trees cut on a control project must 
be regarded as a loss, since it is at present commercially impossible 
so to adjust logging operations that trees scattered over a large area 
can be picked up in a single season. ; 

After the second season deterioration increases steadily, until by 
the end of the seventh season there is little merchantable volume to 
be obtained, and this only in an occasional tree much larger than the 
average or with some other abnormal condition. For example, the 
merchantable volume in the trees cut in 1916 came from two trees 
only, as is shown in column 7 of Table 1. One of these was a large 
tree with a diameter inside bark at stump height of 37 inches, while 
the other, though 11 inches smaller in the same dimension, had an 
unusually resinous butt log. The 760 feet board measure in the 1915 
trees came from the first three logs in a 43-inch tree. 

The criticism may be made that Table 1 is based on insufficient 
data. An examination of the table will show that the trees are well 


ae ee 
q, ¥ Se 
we 


i= 
Wie 


“4 BULLETIN 1140, U. S. DEPARTMENT OF AGRICULTURE. 


distributed by seasons of exposure except in the case of those cut in ; 


1918, of which there are only three, all that could be obtained. The 
basis for this class is insufficient. The cull percentage shows a steady 
increase and the percentage of total trees with merchantable volume 


a steady decrease except in the 1918 trees. This points to a sufficient — 


basis for the other classes. Then, too, during the course of the field 
work the similarity in condition between trees exposed for the same 
number of seasons was quite apparent. _ 

Figure 1, which is a diagrammatic smoothed curve based on Table 
1, illustrates the rate of deterioration of the down timber. 


S20 


PERCENTAGE OF CULL 


2 F <4 ker) 
SEASONS OF EXPOSURE 


Fic. 1—Diagrammatie smoothed curve, illustrating the rate of deterioration of felled 


western yellow pine, 


CAUSES OF DETERIORATION. 


In ‘Table 1 sap-stain is not considered a defect. While this dis- 
coloration does degrade the lumber, discolored wood can still be used 
for a variety of purposes. In this region blue-stain caused by the 
fungus Ceratostomella sp. is most common, while a brown stain, of 
which the causal fungus is probably Alternaria sp.2 is sometimes 
found. Staining is practically confined to the sapwood, rarely pene- 
trating the heartwood. The extent of the stain in a tree is easily 
misjudged. As previously pointed out, there is a very dry outside 
layer of sapwood, too dry to stain, and a hasty examination may show 
bright wood, but deeper chopping will reveal the stain. By the end 
of the first season all the sapwood with the exception of the outer 
layer was heavily stained in the trees examined. In the upper por- 
tions of the trees, where the bark had been left on, this outer layer, 
since it had been kept moist, was also stained. ‘The discoloration 


2 Hubert, Ernest E. Some wood stains and their causes. Jn Hardwood Rec., vy. 52, 
no. 11, p, 17-19, illus. 1922, [Si 


a 


DETERIORATION OF WESTERN YELLOW PINE. 5 


first began along the checks and then spread over the entire sap- 
wood. “Tf stained sapwood is considered a defect the loss for Table 1 
after one season of exposure would amount to 78 per cent in the trees 
cut in April, 1921, and 67 per cent in the trees felled in December, 
1920. ‘This difierence may be mere chance or it may indicate that the 
winter-felled trees for some unknown reason were less susceptible to 
‘discoloration by the time that climatic conditions in spring or sum- 
mer favorable for staining arrived. Observations made on wind- 
thrown yellow pine in this region showed that heavy staining began 
in July. To avoid sap-stain as much as possible trees should be 
logged before that time. 

That the principal causes of deterioration were relatively few and 
well defined is shown in Table 2. 

The most important cause of cull in the trees exposed for one 
season was checks. Checks were confined mostly to the sapwood 
but in some cases extended deep into the heartwood. 


TABLE 2.—Causes of deterioration of felled yellow-pine trees in Klamath 


County, Oreg. 
Cull (percentage of gross volume.) 
Pensens |... 1s Bee 4 he Ses 
When cut. : of yeas | eee 
exposure.) Cheeks. | Sap-rot. e ian felling.| Burned. | Borers. 
1 2 8 cS 5 6 7 8 
Mpa 9a |) hii2s!. 2 tkieee. 1 Po Kelee cede | Pes. eee icccke. oiiclin ileal Bs 3. 
December, 1920...............-- 1 16.2 Bah | wines 0.2 i es 
Lj Ae | 2 16.9 S06") CFA Ye ee eee yj eS Lae 
November, 1919................ 2 11.5 | : Ee | 3.7 D4ai bets otic ace 
2 OS 4 re ro Al ee ue ee 59.4 | 9.6 | 1.2 | | SEN iar) 9 ee 
Spring of 1918..................- Avs s2h sda: 63.4 | A | s~-heoe S/E308 LEE EET oad s. 
ae 5 1.4 53.2 | 15.0 «5 | 9.6 1.9 
Spring of 1916.................-. 6 3.9 63.7 | 14.1 | .8 | IB) 1, 
Spring of 1915.42..........-.-.-- 7 3 | AF | ae PD lead a nga es Ea 


Checking usually began and was most severe on the side of the 
trunk exposed to the direct rays of the sun. Exceptions to this rule 
were found where particularly intense heat had caused severe check- 
ing when the bark was burned. Normally the loss through checking 
in any one tree resulted from several or numerous checks, but in a 
very spiral grained tree a single deep check twisting around the tree 
sometimes caused all the loss. Considering column 3 of Table 2 it 
would seem that the loss through checking decreases with the length 
of exposure after the second season, while it is self-evident that this 
loss should increase slightly or remain about the same. The explana- 
tion is that as sap-rot becomes more severe the checks become obscure 
or disappear completely, and in scaling the loss from this source is 
then difficult to separate from that caused by sap-rot. 

There was little sap-rot during the first season. In fact, the en- 
tire 170 board feet given in Table 2 were obtained from a single tree. 
But by the end of the second season the loss from this cause was 
_ heavy and continued so. After that time sap-rot was the most im- 
_ portant factor in deterioration. In poles and young thrifty stand- 
ards with wide sapwood, sap-rot by amounting to two-thirds or more 
_ of the gross volume often caused the loss of the entire tree. It fol- 


Me —a 


6 BULLETIN 1140, U. S. DEPARTMENT OF AGRICULTURE. 


lowed then that poles and young thrifty standards were subject to 
much more rapid deterioration than large trees, in which the ratio 
of sapwood to heartwood is inverted. 

The upper side of the trunk decayed most rapidly, and the under 


side, the portion resting on the ground, much more slowly. This is: 


probably explained by the retarding effect on the development of 
wood-destroying fungi from the excessive moisture content, lessened 
oxygen supply, and lower temperature of the wood of the under 
side as compared with the upper side. Decay first appeared along 


ie ak ee 


the checks, but avoided the dried outer layer of sapwood. Tongues 


of decay extended down from the ends of the checks. The decay 
then spread from the checks, finally involving the entire sapwood 
with the exception of the outer layer. Where the bark was left on in 
the top, the outer layer also decayed. Barking the tree somewhat 
retards decay, but not enough to be of practical importance, while 
on the other hand it promotes checking. 

Generally it was impossible to determine the exact kind of decay 
in the different trees, but where this was done it was found that a 
white cellulose pocket rot * caused by Polyporus anceps Pk. was most 
common, while a brown friable rot caused by the brown Lenzites 
(Lenzites sepiaria (Wulf.) Fr.) and a yellow-brown friable rot 
caused by Pomes pinicola (Fr.) Cke. occasionally occurred. 

Heart-rot was not found in the trees until the third season of 
exposure. Decay first appeared as tongues running in from the 
sapwood or following in along deep checks. The white cellulose 
pocket rot was most common. 


A negligible amount of loss resulted from breaks, usually in the 


top, when the trees were felled. 

A more important source of cull was fire at the time the trees were 
felled and bucked. This sometimes did considerable damage. When 
the bark was burned, trees with open wounds were very likely to 
burn out along the scar and for some distance in advance. Fire 
scars, particularly in pitchy butts, were common starting points for 
destructive burns. Felling trees across one another or leaving limbs 
resting on the trunk resulted in additional loss from fire. 

The loss caused by wood-boring insects was negligible. Ambrosia 
beetles did not attack the trunk from which the bark had been re- 
moved, while the round-headed and flat-headed borers did not attack 
the trees until sap-rot was well started. 

From the foregoing discussion of Table 2 it is apparent that while 
checks caused some loss (and in a lesser degree so did fire), decay, 
particularly the very rapid decay of the sapwood, is responsible for 
most of the deterioration in these trees. 


CONCLUSIONS. 


The facts brought out in this bulletin should not be considered 
as of value for local application only. The climatic conditions of 
the Klamath Lake region, characterized by a small yearly precipita- 
tion, with a long summer drought, often beginning in the late spring 
and extending well into the fall, and low winter temperatures, are 


’This Gecay has also been called western red-rot. According to Dr. J. R. Weir, : 


Polyporus ellisianus Murr. as known in the West is the same as P. anceps Pk. 


a ee 


DETERIORATION OF WESTERN YELLOW PINE, 7 


exactly similar to those of a great part of the yellow-pine belt of 
eastern California, Oregon, and Washington, and not markedly at 
variance with conditions in other western yellow-pine regions in 
North America. 

These results should prove generally applicable, with minor varia- 
tions, on control projects in western yellow pine. ‘Timber averaging 
smaller than that studied here wili deteriorate more rapidly, while 
the deterioration in larger timber will, of course, be slower. 

The felled and barked trees were completely sap-stained by the 
end of the first season of exposure. If sap-stain is considered a 
defect serious enough to make discolored wood worthless for lumber, 
there is such a large loss the first season that utilization by mid- 
summer is imperative. However, as a rule, stained lumber is only 
degraded and not culled. 

Deterioration is very rapid and is chiefly caused by decay, par- 
ticularly the very rapid decay of the sapwood, followed more slowly 
by the breaking down of the heartwood. The resulting loss is so 
high by the end of the second season that felled trees must be utilized 
by the beginning of the second season, or else the volume of mer- 
chantable wood obtained is so small as to be of little commercial 
importance. Consequently, the timber in most of the trees cut on a 
control project becomes a complete loss, since under present economic 
conditions it is usually not possible to utilize scattered trees over a 
Jarge area within such a limited period of time. 


) Gere ta a 
Vee « a 


we re - nme 
Naik bi ore 5 if hon 
ie ie A a ; i * ee oe 
p cy 7 Anes ef - i he 
a as 2S ‘ r 
~ , a. rate ‘ 
: 7 ¥ Dy t 
Aid . a = 5 
= . As 
es a 
aoe ‘ , —- ee 
- . > F . ae) a! 
i? = ae 
' n ” 7 
, : FES 14s oe 
= ¥ * 1. ie 
: To 
ahi - i a ¥. Re: 85 3 
ry 4 se 
a 
t 


ORGANIZATION OF. THE “UNITED STATES DEPART ny 


AGRICULTURE. 

Secretary of Agriculture _21.- ~~ u.... Henry C, W. 
Assistant Secretary____._--_____-_ RE W. PuGSLEY. - 
Director of Scientifie Work_-_---------------- B.D. Bam, ae 4 
Director of Regulatory Work-—---~--+--~+---~ art 
Weather Bure. 302 a Bia cei F. MA 
Bureau of Agricultural Economics__._.___---_. Henry C. TAY LOR 
Bureau of Animal Industry____.___-__._-____-- JouN R. Mout, | 
Bureau of Plant Industry____._-_------_---_--e. WitiiAmM A. TAYLOR, 
Forest: Service. viu_2ascs_Lollc} jeu ee.) Wao B, Gia 
Bureau of Chemistry. 12-2 ek - WALTER Gay / 

Chief. — 
Bureadiof SetteLo:.i ltou22cet pe. gor py MILTON ae 
Bureau of Entomology___.__-. +e. L. O. Howa 
Bureau of Biological Survey__-____-_----__--- B. W. NELson,. | 
Bureau of Public Roads_.2ntt ig tus bat Toomas H. Mz | 
Fixed Nitrogen Research Laboratory___-----~-- eG. CorrRett, 
Division of Accounts and Disbursements______. A. ZAPPONE, Chi 
Division of Publications__. 24, Be JOHN L. Coss, ¢ 
Pt an OR RY A MI A, = eles CLARIBEL R. fF 

rian. ae 
States Relations Service_____________________- A. C. TruE, Dir 
Federal Horticultural Board________---__-___- C. L. Marat, 
Insecticide and Fungicide Board_____________- J. K. Haywe 
Packers and Stockyards Administration______- CuerstTeR Mor 
Grain Future Trading Act Administration____- the Secreta - 
Office of the Soleitor._.___- = -_--* eee R. W. Witu1aMs, So 


Bureau of Plant Industry_.-.-.--------------. WM. A. ae 
Investigations in Forest Pathology____--_- HAVEN METCALF, PC 


8 


ADDITIONAL COPIES 
OF THIS PUBLICATION MAY BE PROCURED FROM 
THE SUPERINTENDENT OF DOCUMENTS 
GOVERNMENT PRINTING OFFICE 
WASHINGTON, D. C. 
AT 


5 CENTS PER COPY 
Vv 


Washington, D. C. July 21, 1923 


A STUDY OF DECAY IN DOUGLAS FIR IN THE PACIFIC NORTHWEST. 


By J. S. Boycr, Pathologist, Office of Investigations in Forest Pathology, Bureau 
é of Plant Industry. 


CONTENTS. 

Page. Page 
Importance of decay in Douglas fir.......... oh Sotranice Of tite Geen ys. uso. 2 ee eos ee as 7 
Method of coilecting data..............-.--- 2 | Indications of decay in living trees.......... 10 
MMNeL CARINE GOCAY:..-.<--2-----2-+-20---- 3 | Extent ofincipient decay-.............-.-.4 15 
Position of the decays in the tree...........- ZV MR SSUI Cha Gh ange SL MUM oa ing Ta 9 8 8 Ie a Ase ae 16 
Relative importance of the decays.......--- Ah OMtbLOOKs 5. 4, cove tas ays bey qoa sei ith wert 17 
Mer imCaminyliries co). ooln swe nae cc ese | MeuOLALUILe Chie sass ote ae a: cuelees tae Nee 19 


IMPORTANCE OF DECAY IN DOUGLAS FIR. 


Douglas fir is the most important timber tree in the Pacific North- 
west, covering, as it does, the greater part of the foothills and lower 
slopes of the Cascade Mountains and the Coast Range in practically 
pure stands of great density. The stand of this species in Oregon and 
Washington is estimated at 505 billion feet (6, p. 23),1 or nearly one- 
fourth of the remaining merchantable timber in the United States. 

The loss through decay in Douglas fir in this region is very high. 
While some overmature stands are relatively sound a loss of 20 per 
cent in such stands is not uncommon. In certain cases the cull figure 
may reach 50 per cent or more, so high that in timber on difficult 
ground it becomes impossible to log at a profit. It is only in young 
stands of second growth that Douglas fir is uniformly sound. Plate 
I shows defective trees left uncut after logging in an overmature 
stand. In this instance about 25,000 feet board measure per acre 
was left standing. Where clear cutting is practiced numerous logs 
and entire trees remain on the ground after logging, absolutely worth- 
less on account of decay. This isillustratedin Plate II. Practically 
all the large pieces were left because of rot. 

Recognizing the importance of this question, foresters and lumber- 
men in the Douglas fir region have repeatedly felt the need for exact 
information on decay in Douglas fir. This bulletin presents obser- 
vations by the writer and the results of a preliminary study.’ 


1The serial numbers (italic) in parentheses refer to ‘‘ Literature cited ’ at the end of this bulletin. 

2 This study was made in the sammer of 1917 under the direction of Dr. E. P. Meinecke. To him the 

_ writer is indebted for supervision and assistance throughout the course of the field work. The project 

_ was a cooperative one with the Forest Service of the United States Department of Agriculture, and 

acknowledgment is made to Forest Examiner IF. B. Kellogg for his part in collecting the field data. A 

much more detailed study of decay in Douglas fir is now in progress, but will not be completed for several 
years. 


42198—23-——-1 1 


2 BULLETIN 1163, U. S. DEPARTMENT OF AGRICULTURE. 


METHOD OF COLLECTING DATA. 


The trees selected for study were part of a defective, overmature 
stand of pure Douglas fir on the west slope of the Cascade Mountains 
at McCredie Hot Springs, above Oakridge, Lane County, Oreg. 
The area was at an elevation of about 2,000 feet above sea level, and 
the local topography was characterized by moderate slopes and almost 
level benches. The stand was quite typical of the bulk of the Douglas 
fir type on the west slope of the Cascade Mountains. 

Kach tree was felled with a stump height of 14 feet measured at a 
point halfway on the slope. The bole was then cut into 16-foot logs 


to an 8-inch top-diameter limit inside the bark. Complete measure- 


ments were then taken. Next, the logs were split open and any 
further data available recorded. In this way it was possible to study 
each tree very completely, particularly with reference to the character 
and distribution of decay. Volumes of the trees were worked up in 
both board and cubic feet. The board-foot volume included the 
merchantable portion of each tree from the stump height of 14 feet 
to a diameter limit of 8 inches inside bark. The 16-foot logs were 
scaled with the Scribner Decimal C scale and the volume of decay 
determined in accordance with the standard scaling practice of the 
Forest Service (8). 

The cubic-foot volume included the contents of the entire stem 
from the ground level to the tip. In computing volumes the stump 
was considered as a cylinder, each 16-foot log as the frustum of a 
paraboloid, applying the Smalian formula (2, p. 161), the top (that 
is, the section from the 8-inch diameter inside bark to the tip) as a 
cone, and a broken section of the top which did not include the tip 
as the frustrum of acone. The actual cubic-foot volume of decay 
was computed by the same formulas. 


A general idea of the size and age of the trees analyzed is given 


in Table 1. 
TABLE 1 —Size and age of Douglas fir trees studied. 
eg retecaeams of 
yolume. 
Average | diameter tem : Number 
Age class. age peasy a of trees, 
(years). | hig . asis. 
(inches). | “feet | feet 

Al-¢o GO) Fearsijatj cst 2 ed eke eee ee 59 9.5 0.04 4) 1 

Ol tors0i years 2.42 2 ae Agena cles och e eee 68 12.1 -91 0. 62 8 

Sito LOO fyearskiw el SOR eeles hh Da eee Ree 95 14.0 .53 -42 3 
10% G0 120. Yearse 6 ocak Ss ae ol Set do eeeee aan 103 16.3 . 15 .62 3 
121'to 140 years... . Lah eA Oe aa ce eat gedit spel SP 129 16.0 ato 11 1 
IAL to 6D iyears. ...2 bb ob eo -AEd Leo EE See Ue ke (Q) 
161 To T80 ears. ee ss an oye a le ieee a al eps 0 
18}*to.200 ‘years. ee eel 2 eR 195 18.7 1.36 1 ty i 5 
DOU EO 220) OTS oe eS pee A ee 214 25.3 15.49 14, 89 29 
ZZ TOZEO 1 VEATS sO Hees ee ee Renae af tom neat 230 27.5 32.69 33.91 47 
241 $0 260) FOaRScn3 05 < th). 0 eee VLE RSL GAUEE o ek a 245 27.9 10.81 11.26 15 
261'CO 280) WEARS. oe sae eee ol te eine ieee sb Sea 271 28.1 15.81 15.74 25 
28Hto. 800 Fears? a AERA Ok Bos A 284 29.2 1.52 1.63 2 
301 G0,320 Years jugs. See a eel ole tae 309 29.7 6.07 5.97 9 
321 to 340; yearstate-* ) eee eee eae Re inguin ane 333 29.8 10.38 10.22 16 
341.it0..360. YOarS ano Oso de dhe okimenie sere eee 348 28.9 2. 48 2.46 4 
BEUEO SS0MYORES xo osc Ee ey ela Vie et ee oe hae 362 39.6 1.09 1.10 | 

Wombpitied sci hee wee kA eer ere as 238 26.lo)sieveoqum ahet Gets 169 - 


t One tree, too small to consider. 


DECAY IN DOUGLAS FIR. 5 


The trees studied were not clear cut from a given area, but average 
trees both sound and decayed were selected to obtain preliminary 
information on which an extensive study of decay in Douglas fir 
could be based. This will be brought out as the discussion proceeds. 

In all 170 trees were felled, bucked up, split open, and studied. 
One of these was only 2 inches in diameter breast high, so it was 
dropped from consideration, leaving 169 trees with a total volume of 
203,920 feet board measure and 33,703.12 cubic feet. 


FUNGI CAUSING DECAY. 


Four species of fungi are responsible for all but an infinitesimal 
portion of the decay in Douglas fir. They are the ring-scale fungus 
(Trametes pint (Thore) Fr.), the velvet-top fungus (Polyporus schwei- 
mitew Kr.), the quinine fungus (Fomes laricus (Jacq.) Murr.), and the 
rose-colored Fomes (Fomes roseus (Alb. and Schw.) Cke.). The 
decays caused by these four wood-destroying fungi in living trees are 
confined to the heartwood. 

The ring-scale fungus causes decay commonly known as conk-rot 
in this region (ring-scale or red-rot in the pine regions), in which the 
wood is riddled with small white pits or cavities, apparently separated 
by sound wood. ‘This is shown in Plate III, Figure 1. In its incip- 
ient stages, before the appearance of the white pits, the decay appears 
as a pronounced reddish purple or olive-purple discoloration, often 

bounded by a narrow zone of pronounced red color. The sporo- 
phores, or conks, are very common in overmature Douglas fir stands. 
_ These fruiting bodies issue from the tree through knots and are 
_ perennial. They vary in size and in shape from bracketlike to hoof 
shaped. The upper side is a dull grayish or brownish black, rough, 
and with concentric furrows parallel to the hght-brown margin. The 
under side is a grayish brown or rich brown color with large irregular 
pores. The substance or context of the sporophores is corky or 
punky. Plate IV shows the appearance of the sporophores on a 
living tree. : 
. The velvet-top fungus causes a red-brown friable rot in the final 
_ stage. The incipient Aecit is very difficult to detect. It first becomes 
- noticeable as a faint yellowing or browning of the normal heartwood, 
which still seems to be firm and hard but in reality is seriously weak- 
ened. The sporophores, or conks, of this wood destroyer appear 
_ either on the infected tree or on the ground near by and are annual. 
_ They are rather large, with a light-brown upper surface, an olive or 
_ dirty green under surface, and have a cheesy consistency when young, 
_ but when old and dry are a dark rusty brown and corky. Sporo- 
_ phores on the ground have a short thick stalk. Plate V, Figures 1 
_ and 2, illustrate both sporophores and decay of this fungus. 
_ The quinine fungus has a large, conspicuous, whitish perennial 
sporophore, not at all common on living trees. The substance of the 
_ sporophore is white, soft, and cheesy when young and rather crumbly 
and chalky when old and dry, with an exceedingly bitter taste. 
_ Hence the name. On the older sporophores the upper surface is 
' rough and chalky white and brownishin color. The pores are small 
| andregular. Plate VI, Figure 1, shows a sporophore. The typical 
| decay is a crumbly brown rot easily recognizable by its mycelium 
felts or sheets (i. e., closely woven masses of fungus hyphe). This 
_ characteristic is brought out in Plate VI, Figure 2. The incipient decay 
| which appears as a faint brownish discoloration is not easy to recognize. 


= BULLETIN 1163, U. S. DEPARTMENT OF AGRICULTURE. 


The sporophores of the rose-colored Fomes are easily recognized b 
the delicate rose color of the under surface. The pores are small. 
The upper surface is rough, hard, and black. This is illustrated in 
Plate IiI, Figure 2. The decay caused by this organism is a yellow- 
brown crumbly rot, with mycelium felts much less conspicuous than 
those of the quinine fungus. The incipient decay is indicated by a 
faint brownish color, the outer limit of which is sometimes marked 
by a zone of brownish green discoloration. 


POSITION OF THE DECAYS IN THE TREE. 


The decay caused by the ring-scale fungus and that caused by the ) 


quinine fungus are not confined to any one portion of the bole but 
commonly extend throughout the tree. 

On the other hand, the decay caused by the velvet-top fungus is a 
typical butt-rot. Of the 70 infections of this decay in 68 trees, each 
separate focus of the rot in a tree being considered an infection, 94.3 
per cent, or all but 4, were in the stump or butt log. The decay 
usually does not extend higher than the first 16-foot log. In 10 trees 
only did the decay go beyond the butt log, and the greatest upward 
extent in any one case was 37.4 feet above ground level. The average 
for all the butt infections was 10.41 feet above the ground. The 
measurements given include the incipient decay. 

The decay caused by the rose-colored Fomes is usually confined to 
the upper portion of the tree in connection with dead tops, and often 
the rot does not extend into the merchantable portion of the infected 
tree. In all, there were 46 infections of this rot, and all but 9 of 
these were in the upper bole. Of those in the upper bole, 18, or 
almost 50 per cent, were in the top beyond the 8-inch diameter limit 
and caused no loss in merchantable volume. 

For the sake of brevity in the remainder of this paper, the decays 
caused by these four fungi will be designated as follows: 


Velvet-top fungus ......52..2ac3.-¢.. ae eee red-brown butt-rot. 
Ring-scale fungus.) sea cul lope ap mere gee oa conk-rot. . 
Ouihine TUBB, .’ nda snc d dsr Becks ene eee brown trunk-rot. 
Rose-colored Fomes... \.. 2... cc pate cece eae yellow-brown top-rot. 


When used in tables the designations will be simply butt-rot, conk- 
rot, trunk-rot, and top-rot. 


RELATIVE IMPORTANCE OF THE DECAYS. 


Conk-rot is responsible for by far the greatest amount of cull in 
Douglas fir. In fact, if the species was free from this defect it would 
oe its place with the pines as a sound tree. This is brought out in 
Table 2. 

In considering Table 2 it must be remembered that it is not based 
on trees clear cut from a given area. Consequently the figures on 
the percentage of infected trees and volume of decay are not indica- 
tive of the actual loss through decay in stands of Douglas fir, but 
they do indicate the relation of the various decays. Under ‘unknown 
rots’”’ are placed a number of small infections of decays whose cause 
could not be determined and one infection caused by Ganoderma 
oregonense Murr., which resulted in a slight loss. | 

Conk-rot stands out as the all-important cause of decay. The 


7 


volume destroyed by this decay in comparison with the others is far — 


j 
| 
| 


a 


j 


j 


DECAY IN DOUGLAS FIR. 5 


greater than the ratio of infected trees would indicate. For example, 
only about one-third more trees are infected with conk-rot than with 
red-brown butt-rot, yet the board-foot volume of decay is slightly 
more than 18 times as great. Conk-rot is usually quite extensive in 
an infected tree, particularly in the mechantable portion of the bole. 


TABLE 2.—Relative importance of the different kinds of decay in Douglas fir. 


Volume of decay, Infections. 
percentage of gross 
volume. eee 
] 
Kinds of decay. viet. ALP it) 33) pereent- Average volume. 
age of Number fees 
i total. i 
5 d ag ‘ basis. total. Board Cubic 
; 3 feet. feet. 
OGLE NO) |, Se ae 38. 4 22.5 61.0 118 41.6 663 64.2 
Wotiakeror ce ot tee 257 1.3 5.9 15 5S} 369 28.7 
IBALL RC ae eS er ail 1.2 40.2 70 24.6 62 5.9 
PRON ees eens. Soe s ces sm +s 1.6 1.0 22.5 46 16.2 72 7.0 
WNKHOWMN TOtSiessessesssets ss. a al 18.9 35 12.3 4 1.0 
Omimted <. Dee tks 44.9 26.1 87.6 284. | sheen 323 30.9 


While only a few trees showed brown trunk-rot in comparison to 
those with red-brown butt-rot and yellow-brown top-rot, yet the 
volume of brown trunk-rot is greater than either of the others, 
particularly in board feet. This is due to the fact that brown trunk- 
rot when it does occur is quite likely to cause the loss of all or most 
of the merchantable portion of the affected tree. Yellow-brown top- 
rot and red-brown butt-rot, being localized, result in much less loss 
per tree, but make up for this in the many more trees with these 
decays. The greater loss through brown trunk-rot in board feet as 
compared to cubic feet in relation to red-brown butt-rot and yellow- 
brown top-rot is understood when it is remembered that the former 
is usually in the merchantable portion of the tree, while the latter 
two are often in the stump and top, which are not included in the 
board-foot volume but are figured in computing the cubic-foot volume. 

Furthermore, red-brown butt-rot is of more importance than the 
figures would indicate, since seriously affected trees are quite subject 
to windfall, breaking off near the ground. Then, too, this decay 
destroys the valuable heartwood of the butt logs. 

Of the total of 169 trees, 21 were free from decay, while in the 
remaining 148 there were 284 infections, or an average of 1.9 infections 
per infected tree. Some trees had as many as 6 individual infections. 
Again, in considering the infections conk-rot stands out both in the 
number of infections and particularly in the average volume of 
decay per infection. Trunk-rot has a high average volume of 
decay per infection, which shows again that this rot is of minor 
importance only because of the limited number of infections, but 
when a tree is once attacked destructive and extensive decay usually 
results. 

MECHANICAL INJURIES. 


Mechanical injuries on trees are of importance in that besides some- 
times reducing the annual increment or causing an actual loss in 
merchantable volume from the mere presence of the injury the 
afford access to the heartwood of the tree for the spores of wood- 

destroying fungi. 


6 BULLETIN 1163, U. S. DEPARTMENT OF AGRICULTURE. 


Wounds in Douglas fir, though quite common, are mostly super- 
ficial and heal rather rapidly. Rapid healing is particularly the 
case in younger trees. Wounds as a rule callus very irregularly, and 
as a result it is usually difficult or impossible to determine the exact: 
dates when scars were made and callused over by counting the annual 
rings. In this respect Douglas fir differs strikingly from the clear- 
cut, regular calluses characteristic of incense cedar and white fir. 
Turthermore, injuries in Douglas fir frequently result in the formation 
of prominent burls. | 

Of the trees studied, only 11 were entirely free from scars. The - 
remaining 158 trees had 508 scars, open and healed over, an average 
of 3.2 wounds per tree. Table 3 shows the relative frequency of the 
various types of scars 


TABLE 3.—Scars in Douglas fir. 


Number ofscars, basis.| per- Number of scars, basis.| per- 
LS cent- cent- 
Type of Scar. ne age ¢ Type of scar. a age <a 
Heale tota Heale tota 
Open.| “over, | Total. | scars. Open.) “over, | Total-| scars. 
Fire sears ......222. 43 237 280 55. ||| Spike (tops)... ee ee eee 10 2.0» 
Falling-tree scars. - . 25 61 86 16.9 || Broken tops: . .o)j..aceklaweeeeen 58 11.4 
Lightning scars..... il 38 49 9.6 || Unknown scars.... UM ed eee ag 7 1.4 
Sapsucker scars... .. 1 | 9 10 2.0 —--— 
Blaze sears... 2.2... 1 0 1 ap Total... ee ucet eee FS alae g ome 
Frost cracks........ | 0 7 7 1.4 
J 


In Table 3 the healed-over, closed, or occluded sears are greatly in 
the majority. This indicates that the wounds were mostly superficial 
and that this tree species heals rapidly after wounding. 

The predominance of fire scars is striking. While it was not pos-- 
sible to determine the years in which the fires occurred, for the reason 
stated previously, it was noticeable that most of the injuries of this 
nature had happened when the trees were relatively young—that is, 
below 20 inches diameter breast high, more or less. This coincides. 
with our knowledge of fires in the Douglas fir region. In young 
stands fires which run over the surface of the ground injuring but 
not killing the trees are common, while in mature or overmature 
timber fires have a tendency to run through the crowns, killing all but 
scattered individuals outright. 

Burls may form as the result of fire scars, but more common are 
swollen, or churn, butts as the result of severe scars. These churn 
butts extend usually from the ground level up the trunk slightly 
higher than the limit of the fire scar. Even though a fire scar has. 
been healed over for a long time and there is no churn butt or burl 
to indicate its presence, it can often be detected by the variation 
in the appearance of the bark over the healed wound. This appear- 
ance is hard to describe, but not difficult to judge after a little 
experience. 

Next in numerical importance to fire scars were wounds caused by 
falling trees. These, of course, are more common in mature and 
overmature stands than in second growth. Trees may die and ulti- 
mately the snags will fall, or again large trees with butt-rot are 
quite subject to windfall. Such trees on their way down strike 
others, breaking off the tops or limbs or bruising the trunks and 
knocking off pieces of bark. Falling-tree scars rarely extend deeply 
into the tree. 


DECAY IN DOUGLAS FIR. 7 


Lightning wounds occasionally occurred, although the Douglas fir 
region is not subject to severe lightning storms. Injury by sap- 
suckers was rare, and the few scars found were very superficial. 
These birds do not seem to select a single tree and attack it year 
after year, as they often do in other tree species. I rost cracks were 
not common. This was to be expected, since the Douglas fir region 
as a whole is not subject to sudden extreme variations of temper- 
ature from relatively warm to very cold. 

There were 10 spike-topped trees. Half of these dead tops had 
been caused by lightning, while two of them resulted from falling trees. 

On the other hand, trees with broken tops were not unusual. The 
most common cause of such injury was falling trees. This source 
accounted for 31 of the broken tops. Snow was responsible for 4 and 
lightning for 3, while the remaining 20 could not be determined. 
A load of ice or heavy wet snow is of more importance in causing 
broken tops than appears from these figures, but most of the damage 
occurs in young stands. According to observations of the writer and 
others, heavy snow or ice injury occurred about 1888*% in the imme- 
diate section where this study was made. The damage was very 
apparent from the number of broken tops, all having been made at 
the same time, in second-growth timber. ; 

Broken tops require a long time to heal. Even after the volunteer 
top is well started the stub of the old top protrudes, and when this 
is finally grown over a slight crook still remains in the bole, which 
does not entirely disappear for years. 

In considering the data presented, it may appear from the total of 
508 scars on 158 trees that the trees were subject to excessive injury. 
It must be remembered that most of the wounds were superficial. 
Then, too, several small scars on a single tree might be made by the 
same agent. For example, one fire or one lightning stroke can 
readily cause several scars on a tree. Owing to the impossibility of 
_ determining with any accuracy the dates of injury in Douglas fir, it 

_ was necessary to consider each scar, with a few exceptions, as separate 
_ and distinct. 
ENTRANCE OF THE DECAYS. 


The wind-blown spores from sporophores of wood-destroying fungi 
attacking the heartwood of living trees must light on exposed dead 
wood in order to cause infection. But the type of infection court 
varies with different species of decay, and it is of importance to 
determine the common means of entrance in each case, since in so 
far as the infections occur through controllable mechanical injuries 
there is a possibility of reducing the amount of loss. 

; Table 4 shows the points of entrance for conk-rot. From this 
_ table it can be seen that knots or branch stubs are responsible for 
the major portion of the infections, and, what is far more important, 
all but an infinitesimal portion of the total volume of conk-rot 
resulted from these infections. 

_ ‘The infections of brown trunk-rot both numerically and in the 
_ resulting volume of decay. were rather more evenly distributed, as 

_ can be seen from Table 5; but here again knots predominate. 


_ .* This date is from an unpublished record furnished by the Forest Service. 


8 BULLETIN 1163, U. S. DEPARTMENT OF AGRICULTURE. 


TABLE 4.—Infection court of conk-rot in Douglas fir. 


| 


Infections. 


Percentage of total. 


Infection court. Average volume. 


Number, Volume. 
basis 
Number 

Board Cubic Board Cubic: 

feet. feet. feet. feet... 
riots} 22 dbp etane! .wee teagh £6. he 98 83.0 99. 62 99. 48 796 77.0 
HIn@ Soars. Joyal ict cage ete eed Dee = 10 8.5 .04 .03 3 «2 
Falling-tree- wounds :f P22. ire eee 3 2.5 0 -05 0 1.4 
Lightning: scars)! ciissii3is eas. RE os 4 3.4 34 43 68 8.2 

‘Dead Tops... og. c. tah eee ee oe 1 -9 0 0 -. 0 0 

Unknown'scars?. 2. 31) .. 9315. See. 2 1? 0 0 0 0 


TaBLE 5.—Infection court of trunk-rot in Douglas fir. 


Infections. 


Percentage of total. 


Infection court. Average volume. 


Number, Volume. 
basis. a. 
Number 
Board Cubic Board Cubic 
feet. feet. feet. feet. 
Kytts 26s AR 2). OL JD ie. 7 46.7 44.6 46.1 353 4 
ITOSCETS cae Po Se ee ee ee a 1343 0 0 0 
Falling-tree scars..........---..- Cg Oe a 26.7 30.0 26.9 415 29.0 
2 13.3 25.4 26.9 705 58.0 


hightning sears. r7z- sc. «dence to $e seaeine - 


Table 6 brings out the relation between fire and red-brown butt-rot. 
The major portion of the infections entered through fire scars, and 
the resulting volume of decay was proportionately much higher. This 
butt-rot also attacks the roots and can probably be spread by the con- 
tact of a diseased root with a sound one. About 11 per cent of the 
volume of rot is apparently traceable to this method of infection. 
Besides these two the other infection courts are of no importance. 


TaBLE 6.—Infeclion court of butt-rot in Douglas fir. 


Infections. 


Percentage of total. 


Infection court. Average volume. 


Number, Volume. ¢ 
basis. | 
Number 
| Board Cubic Board Cubic 
feet. feet. feet. feet. 
Rinotdt 64 city Sespte ese ae 1 1.4 1.4 0.5 60 2 
MATCGEATS. OSs be. case eee cate aL eee 41 58.6 78.2 79.1 83 3. 
Falling-tree, searsiti¢icege as. 0 ese ee 4 He 327 50 40 5. 
hightning scars. 259. SNA veer ese oc 4 oi” 239 1.8 28 A. 
ES 5Y 0 > MRR SRI PRSRNN YORE OE SS ar “OY De RH TR a 16 22.9 10.8 11-5 29 3. 
Unknown Scars: 2322225: aes 4 5a 3.4 24 38 2. 


NOoONOCO 


SS 


DECAY IN DOUGLAS FIR. 9 


Yellow-brown top-rot, true to its name, in Table 7 shows the 

eatest number of infections entering through dead tops, which 
include broken and spike tops. Knots, though with fewer infections, 
were responsible for a greater volume of decay, since such infections 
usually occurred lower down on the bole where there was more 
heartwood for the fungus to work on than was the case when the 
wood destroyer entered through a dead top. The large volume of 
decay the cause of which is recorded as ‘‘ unknown” resulted from 


an extensive infection which could not be traced to its source. 


TaBLE 7.—Infection court of yellow-brown top-rot in Douglas fir. 


Infections. 


Percentage of total. | 


Infection court. Average volume. 


Number, Volume. 
basis. 
Number. 
Board Cubic Board Cubic 
feet. feet. feet. feet. 
ere tere nee 12 26.1 35.8 35.7 98 9.6 
Cyn Sys) 8 RR a A a 2 4.3 8.2 6.6 135 10.6 
SS a eee ere ae rf 15.2 7.0 1.9 33 9 
ea i ae 5 10.9 15.4 15.0 102 9.7 
oo) De ee ee ee ee ee 18 39.1 17.0 23.8 31 4.3 
4.3 16.7 17.0 275 27.5 


Table 8 shows the infection courts of the unknown decays. Some 
of these were undoubtedly infections of the four common rots, but 
were abnormal or so small that they could not be accurately identified. 


TaBLE 8.—Infection court of unknown rots in Douglas fir. 


Infections. 


/ Percentage of total. 


Infection court. Average volume. 


Number, Volume. 
pasis. a he 
Number. 
Board Cubic Board Cubic 
feet. feet. feet. feet. 

eer ee ete ne ee A 5 14.3 0 0 0 0 
Fire:scars ....'....- SFE ES Se ae oC ae eee 12 34.3 80.0 62.5 10 rs 
TAGE BCATS Fee ce 2 ok Wheaten ce eee ls. 4 11.4 20.0 8.8 8 8 
CRT e ees ee UE ee el ae oo 11 31.4 0 20.8 0 -6 
LaRosa I eee oe a 3 8.6 0 7.8 0 9 


In Table 9 the data in Tables 4 to 8, inclusive, have been combined. 
Knots were responsible for the greatest number of infections and a 
proportionately greater loss through decay. 

Of all the infection courts fire scars, which were only responsible 
for 4.2 per cent of the total rot volume, are the only factors that can 
be directly controlled. With the increase of efficiency in fire-protec- 
tion methods, injury from fires is being steadily reduced. But the 
other 95.8 per cent of the decay is traceable to sources that can not 
be controlled. Knots, falling trees, lightning, and snow or ice will 

42198239 


10 BULLETIN 1163, U. S. DEPARTMENT OF AGRICULTURE. 


be present in Douglas fir stands in the future, no matter how well 
regulated. Consequently, the reduction in the quantity of rot in 
Douglas fir by a reduction in the scars caused by contrallabla 
mechanical injuries can amount to little. 


TABLE 9.—Infection court of combined decays in Douglas fir. 


Infections. 


\ Percentage of total. 


¢ 
Infection court. Average volume. 


Number, Volume. 
basis 
Number. 
Board Cubic Board Cubic 
feet. feet. feet. feet. 
OMOLS). ral co bce dchecs ost ae ae on 123 43.3 | 89.2 89.2 664 63.9 
ine Sears 455. oc: hie eee 67 23.6 4.2 4,2 57 5.5 
Ealling-tree-scars.) oc.2 2 Ao 18 6.3 2.2 LT. 114 8.2 
Digiiningpeara. le ie Ed 19 6.7 2,0 2.4 123 11.5 
DG Ope. Sees ts eae oe eee 39 10.6 6 1.0 19 2.8 
OOUS . a: Soe Shan eee ae ero at 19 6.7 .5 -.6 25 2.6 
Wnktnownisears 22: SR ao re ok ee 8 2.8 .8 ei 88 8.0). 


While it is true that infection courts resulting from all mechanical 
injuries are of little importance in the total volume of decay produced 
as compared to knots or branch stubs, it is of academic interest to 
determine the kind of scar most susceptible to infection in the trees 
studied. This is brought out in Table 10. at 

54000 iO 
TABLE 10.—Susceptibility to infection of various scars in Douglas firs 


——— 


Scars infected. Scars infected. 
Number Number 
Type of scar. nf sengiay Type of scar. of Scars. 3 

Number. | Per cent. Number.| Per cent. 
Fire scars. i i.252.5% 280 67 23.9 || Spike tops......... : 
Falling-tree scars. . 86 18 20.9 || Broken tops ....... \ 68 30 44.1 
Lightning scars ... 49 19 38.8 || Unknown scars.... i ad 100 
Sapsucker scars ... 10 0 0 —_— | —_—|—_— 
Blaze scars ........ 1 0 0 T otal ..i2- S22 508 141 28.0 
BPOSHCrAGS, oes | 0 0 


Dead tops, which include spike-tops and broken tops, followed 
by lightning scars, were most susceptible to infection, wee to 
Table 10. 


INDICATIONS OF DECAY IN LIVING TREES. 


Recognition of the indications of decay in standing Douglas fir or 
in logs is of the greatest importance from a practical standpoint. 
A comparison of the cruise and actual cut on ma operations in 
overmature decadent timber brings this out foraibly. At present 
there is a great deal of confusion and misinformation among foresters 
and lumbermen in regard to the detection of decay in living trees, 
and the specter of “hidden defect” assumes unnecessary proportions. 
In fact, decay in Douglas fir is more easily detected than in most 
species ‘subject to a large amount of rot. 


PLATE I. 


Iture. 


gricu 


Bul 1163, U. S. Dept. of A 


a NE 


DEFECTIVE DOUGLAS FIRS LEFT STANDING AFTER LOGGING. 


The principal defect is decay caused by the ring-scale fungus. 


23——=8 


42198 


PLATE II. 


Bul. 1163, U. S. Dept. of Agriculture. 


ee vee 


NEN edeiges 


“i 
wigs 


Se | 


LOGGING. 


A PRACTICALLY PURE STAND OF OVERMATURE DOUGLAS FIR AFTER 
Nearly all the large pieces were left because of rot, principally decay caused by the 
(Photographed by D. C. Ingram.) 


ring-scale fungus. 


PLATE III. 


Bul. 1163, U S. Dept. of Agriculture. 


“snsunj sty) Aq 
SOMO] PIIO[OI-9SO1 dy} JO 9 


posneod 101 UMOIG-MOTIVA 9} PUB 
,oydo-ods 8 Jo sovjins oddn oy} SMOYS STU 


‘dOL Yl4 SVISNOG V AO NOILOAS SSsO¥O—'S ‘DIF 


‘UOTIBIO[OOSIp sTdind Yystppol B A Pe1VdTNUT ST JoI sy} Saseys 


quetdiour szt uy 


‘ABoop oy} JO 98Rqs [eoIdA} oy} SoVeIISN]I SIM, 


“SNONNSA AIVOS-ONIY, AP GSSNVO LOY-ANOO—"| ‘SIs 


PLATE IV. 


1163, U. S. Dept. of Agriculture. 


Bul. 


IN THE 


ROT 


INDICATING CONK- 


HEARTWOOD OF THE TREE. 
(Photographed by G. G. Hedgcock.) 


SPOROPHORES OF THE RING-SCALE FUNGUS, 


Bul. 1163, U. S. Dept. of Agriculture. PLATE V. 


FiG. |.—SPOROPHORES OF THE VELVET-TOP FUNGUS ON THE BUTT OF A 
LIVING DOUGLAS FIR. 


These sporophores indicate red-brown butt-rot in the tree. (Photographed by G. G. Hedgcock.) 


Fic. 2.—RED-BROWN BUTT-ROT CAUSED BY THE VELVET-TOP FUNGUS. 


Only a thin shell of sapwood remains. Trees so badly decayed are subject to windfall, 


particularly if the rot extends into the roots. (Photographed by G. G. Hedgcock.) 


Bul. 1163, U. S. Dept. of Agriculture. PLATE VI. 


FIG. |.—SPOROPHORE OF THE QUININE FUNGUS. 


These conspicuous whitish fruiting bodies are not common on living trees, but are found more 
often on dead down timber. The sporophore has a very bitter taste. 


Fic. 2.—BROWN TRUNK-ROT CAUSED BY THE QUININE FUNGUS. 


The decay is usually extensive in an infected tree 


wr 


Bul. 1163, U. S. Dept. of Agriculture. PLATE VII. 


BURL ON A DOUGLAS FIR LEFT STANDING ON A CUT-OVER AREA. 


Because of the burl the tree was thought to be badly decayed. Burls do not indicate decay 
Compare with Plate VIII. 


PLATE VIII. 


1163, U. S. Dept. of Agriculture. 


Bu.. 


a 


cath, cand 


* a8 Be 


SWOLLEN KNOTS OR BLIND CONKS ON DOUGLAS FiR. 


Compare with Plate VII 


These indicate conk-rot in the tree. 


DECAY IN DOUGLAS FIR. rT 


DEAD LIMBS. 


_ Large trees with many dead limbs in the lower crown are no more 
likely to be decayed than a normal tree. Such ‘‘wolf trees,” as they 
are known to the forester, merely grew faster than their neighbors, 
and their branches did not die so soon through lack of light; conse- 
quently it requires a longer time for these large limbs to drop off 
and for the branch stub to heal over. 


BRANCH FANS. 


Groups of branches, radiating like a fan from one point, are not 
uncommon on Douglas fir. These branch fans have been considered 
by some persons as indications of decay. A little thought will show 
that this is not within the realm of probability. That decay in the 
dead heartwood could directly affect the vital growing portion of 
the trunk of a tree in such a way as to cause abnormal branching is 
directly contrary to all our knowledge of growth and development 
- of trees. In all, these branch fans were found on 32 trees, varying 
from 1 to 15 on a single tree, with an average of 4.4. Of these 32 
trees, 2 were free from decay, while in 19 the infections were very 
light, rarely causing a loss of more than 10 board feet, and the branch 
fans were not on the same portion of the trunk as the decay. There 
was a considerable volume of decay in each of the 11 remaining 
trees, but in 7 of these the decay was in the lower or middle portion 
of the trunk, while the branch fans were above it in the crown. In 
only 4 trees were part or all of the branch fans found on the decayed 
section of the trunk. -These figures indicate the complete lack of 
even an empirical relation between branch fans and decay. 


BURLS, 


Douglas fir when bruised is subject to burls at the point of injury, 
but it is questionable whether or not all burls are caused by wound- 
ing. ‘Such burls are a disorganized mass of wood tissue with a 
enarled or twisted grain. This formation is a direct response to the 
irritation caused by the injury. Burls are often considered to 
indicate decay. Plate VII shows a tree left uncut on a logging oper- 
ation because it was presumed from the presence of the burl that the 
tree was badly decayed. Data showing the relation of decay to burls 
in the trees studied are presented in Table 11. The number of burls 
to the tree varied from 1 to 20, with an average of 3.6. 


TABLE 11.—Relation of burls to decay in Douglas fir. 


Character of data. Number. | Per cent, 
cect ce inane de san sacs ncinnscopes sh eweescnacnesecepeccete 43 [oo gescacee 
Seperr eres ri sand NO Mech y fy 555 J2 CRC. Seek LL Se kh Skis de se cnicicleinee 6 14.0 
Trees with burls and decay on different sections of the trunk....................-- 19 44.2 
Trees with burls and decay on the same section of the trunk...............-------- 18 41.9 


Analysis of the data in Table 11 demonstrates that the presence of 
burls does not mean decay in the tree. Of the trees with burls 14 
per cent were free from decay, while in 44.2 per cent the rot and 
_ burls did not occupy the same section of the bole. Burls on the 

_ butt of the tree, however, are sometimes an indication of decay, since 
_ burls in this position often result from wounding by fire, and fire 
_ scars are quite commonly infected with red-brown butt-rot. 


12 BULLETIN 1163, U. S. DEPARTMENT OF AGRICULTURE. 
CONK-ROT. 


The decay causing by far the greatest loss in Douglas fir is relatively 
easy to detect. Sporophores of this decay occur abundantly. This 
is indicated by the local name of conk-rot used in the Pacific North-— 
west. Lumbermen observed the unusually common occurrence of 
sporophores, or ‘‘conks,” on infected trees, as compared to those 
with other decays, and the name followed. The prolific development 
of sporophores is shown by the fact that of 83 trees with sporophores 
there was an average of 14.4 per tree, or a total of 1,196. Considering 
all infections both with and without sporophores there was an average 
of 10.1 sporophores per infection, or 1 for every 6.34 cubic feet of 
conk-rot in the trees and 1 for every 65 board feet. 

It is of interest to consider the orientation of these sporophores. 
Moller (4), working with the same fungus, found 89.4 per cent of the 
sporpaorcs on the westerly side of the trees. He explained this by 
the facts that the prevailing winds were from the west and the trees 
were most strongly struck by rain on the west side, and consequently 
the branch stubs (a very common point of infection) were more moist 
on that side. Weir and Hubert (7, p. 30) ,in their work with the Indian- 

aint fungus (Echinodontium tinctorvum EK. and E.) on western hem- 
ock (Tsuga heterophylla (Raf.) ten found that most of the 
sporophores had a northwest to north-northeast orientation. The 
same workers (8, p.18), studying conk-rot in western white pine 
(Pinus monticola Doug.), found the largest percentage of the sporo- 
phores develope ®on the west side of the tree, with the smallest per- 
centage on the southeast side. Table 12 shows the orientation of 
the sporophores on the trees studied. 


TABLE 12.—Orientation of sporophores of conk-rot in Douglas fir. 


Orientation of sporophores. 


Character of data. 


NW N NE E. SE 8 Sw w 
Number of sporophores.............. 212 291 202 91 144 77 96 79 
Pereentageiof total .../...0..0..2.006- 17.8 24. 4 17.0 7.6 12.1 6, 52h | 28i 6.6 


The largest percentage of sporophores occurred on the north side 
of the trees and the smallest percentage on the south side. Adding 
the sporophores on the north, northwest, and northeast it is seen 
that 59.2 per cent were in the northerly grouping. Following this 
system gives 36.7 per cent easterly, 26.7 per cent southerly, and 32.5 
per cent westerly. The northerly direction clearly predominates. 
This is logically explained by the fact that there is less light on the 
northerly side and, consequently more moisture, particularly during 
the growing season, which in this region is a long dry period inter- 
rupted by occasional thundershowers of brief duration. Conditions 
on the northerly side of the trees are therefore more favorable for 
infection and the subsequent development of sporophores. 

As a rule very little rot develops in a tree before a sporophore 
appears, or if not a sporophore at least a swollen knot, or “ blind 
conk,”’ as it is colloquially termed. The sporophores can not pene- 
trate the unbroken bark and issue only through knots or branch 


@ 


DECAY IN DOUGLAS FIR. 13 
stubs not yet occluded. A swollen knot is the initial stage of a 
sporophore in which the substance forming the conk is growing out 
through a knot and forcing out the bark. The pressure may also 
cause an increase in the width of the sapwood immediately around 
the knot, which accentuates the swelling. Swollen knots are illus- 
trated in Plate VIII. A swollen knot is just as good an indication 
of the presence of decay as asporophore. Often the sporophore never 
develops beyond this stage, remaining abortive. Chopping into one 
of these knots reveals a brown, soft, corky or punky context, the same 
as in a fully developed sporophore. Plate III, Figure 1, shows a sec- 
tion through part of a decayed knot. 

The effect of fire on sporophores or swollen knots is striking. 
When mature timber is swept by fire, the flames running along the 
trunk of the tree can not burn off the thick bark. However, the 
corky context of the sporophores and decayed knots burns readily, 
and this results in rounded, blackened hollows extending for several 
inches into the tree where the fire has burned out the decayed knots. 
This makes it possible to judge in a measure the extent of conk-rot 
in recently fire-killed Douglas fir. 

That the development of swollen knots and sporophores follows 
rather closely the progress of conk-rot in the heartwood is brought 
out in Table 13. 


TaBLE 13.—Relation of sporophores and swollen knots to conk-rot in Douglas fir. 


Infections. Volume of decay. 


Percentage of total. 
Average per 


Decay. Per- tary Ey infection. 
yum cent- Gross. Of conk-rot. 
basis. | 28° of 
* | total 
Board | Cubie | Board | Cubic | Board | Cubie 
feet. feet. feet. feet. feet. feet. 
With sporophores so 006i e oso. 2. 96 81.4 | 36.83 | 21.71 | 95.94 | 96.51 782 76.2 
Without sporophores................ 22 18.6 1.56 .78 4.06 3.49 144 12.0 
MVitniswollen knots: ... 205-6 Sol... 108 91.5 38. 39 22.49 99. 95 99. 97 725 ase 
Without swollen knots.............. 10 855 .O1 OL . 04 . 03 3 2 


Table 13 shows that while there was a noticeable percentage of the 
infections which did not develop sporophores, these infections were 
very small, as is indicated by the volume percentages and the average 
volume per infection. The relation is even more striking with swollen 
knots, where the volume percentages and the average volume per in- 
fection of those infections without swollen knots is so small as to be 
negligible. . 

This means, then, that it is possible to pick out rather accurately 
the trees in a stand affected with conk-rot. When high up in a tree 
among the branches swollen knots, or even sporophores, are not easily 
seen, but if overlooked there it does not make so much difference in 
the accuracy of an estimate, since the volume of the top logs is rel- 
atively insignificant in the total. 


EXTENT OF CONK-ROT. 


It is not only possible to pick out the decayed trees, but it is also 
feasible to judge with some exactness the normal extent of conk-rot. 


14 BULLETIN 1163, U. S. DEPARTMENT OF AGRICULTURE. 


In the trees studied it was found that the average extent of decay, 
including typical and incipient decay, above the highest sporophore 
was 20.1 feet. This was based on 83 infections. In two infections 
the decay ended at the height of the top sporophore, and in one tree 
the rot extended for 61 feet above the highest sporophore. When 
the downward extent of conk-rot below the lowest sporophore was 
considered, it was necessary to discard those infections in which the 
decay extended into the stump. Based on only 33 infections, the 
average downward extent was 13.9 feet. The average of both 
upward and downward combined was 18.3 feet. he aoe 

The same figures for the highest and lowest swollen knots were as 
follows: Upward extent, 9.5 feet, based on 93 infections; downward ex- 
tent, 9.2 feet based on 41 infections; combined average, 9.4 feet. In 
one tree the rot extended for 45.2 feet below the lowest swollen knot. 
This difference in the extent of decay beyond sporophores as 
compared to swollen knots is due to the fact that the swollen knot 
in many instances is the initial stage in the development of a normal 
sporophore, and consequently by the time a sporophore appears the 
decay has been in the tree longer and has progressed farther than at 
the formation of a swollen knot. 

These data mean, then, that it is possible to approximate the 
volume of conk-rot in defective trees when cruising. The figures, of 
course, should not be applied to an individual tree as such, but should 
be used in estimating the individual components of a stand in order 
to secure an accurate figure on the total loss through conk-rot. In 
actual practice the writer would use 20 feet as the upward or down- 
ward extent of decay beyond the highest or lowest sporophore and 
10 feet as the figure for swollen knots. In other words, in the case 
of a decayed tree with sporophores the trunk would be considered 
unmerchantable from a point 20 feet below the lowest sporophore to 
a point 20 feet above the highest sporophore, while for swollen knots 
the distance would be reduced to 10 feet below and above. These 
figures are easy to remember and have checked well with the writer’s 
observations since this study was made; but for greater accuracy in 
any given locality it is well to study felled trees and watch long logs 
through the mill, so that these limits ean be corrected to fit local 
conditions. 

RED-BROWN BUT?-ROT. 


Sporophores are, of course, the best indication of decay. The 
sporophores of red-brown butt-rot beimg annual are not common 
except in favorable seasons for their development, but can always 
be found now and then in a locality where the trees are affected. 
However, the best clue is fire scars. Noticeably fire-scarred trees 
are commonly infected with this decay. Of the 125 trees with fire 
scars that were studied, 41, or 33 per cent, were infected with red- 
brown butt-rot. Healed fire scars can often be detected by a 
variation in the appearance of the bark over the wound or by 
swollen or churn butts. There are no swollen knots with this decay. 


BROWN TRUNK-ROT. 


Brown trunk-rot is rather hard to detect. Swollen knots are not 
formed. Sporophores are rare on living trees, but when they do 
occur. they are very conspicuous and not readily overlooked. 


| DEGAY IN DOUGLAS FIR. 15 


Furthermore, observation shows that they indicate extensive decay in 
the tree. Only one tree studied had sporophores of this rot, and the 
decay volume in cubic feet was 31 per cent and in board feet 74 per 
cent of the gross volume of the tree. But the total loss caused by 
this decay was triflmg. (See Table 2.) 


YELLOW-BROWN TOP-ROT. 


-Yellow-brown top-rot also is rather hard to judge. Swollen knots 
do not accompany the decay. Sporophores are not uncommon, 
particularly with the more extensive infections. In the trees studied, 
seven infections, which resulted in 42 per cent of the cubic-foot 
volume and 41 per cent of the board-foot volume of yellow-brown 
top-rot, had developed sporophores. However, the sporopheres are 
commonly so high up in the trees that they are easily overlooked 
and, in fact, are often completely hidden by the branches. Broken 
or spike tops commonly indicate infection (see Table 7). The 
aggregate loss caused by this decay is small. | 


INDICATIONS OF DECAY IN FELLED TIMBER. 


‘The estimate of the extent of defect in logs or felled timber is 
much easier than in standing trees. The red-brown butt-rot is 
revealed in the butt cut, and its upward extent can be more closely 
approximated. Knots can be tested carefully for signs of rot, and if 
the timber has been bucked the ends of the logs can be examined for 
typical decay or the discolorations caused by incipient decay. How- 
ever, if the logs have been exposed to the weather for several months 
these discolorations fade and can not be seen. 

It is not at all difficult to judge quite accurately the extent of 
conk-rot in felled Douglas fir by chopping into the knots to reveal 


the brown corky context of the abortive sporophore. 


EXTENT OF INCIPIENT DECAY. | 


A knowledge of the vertical extent of incipient decay, which is the 
term used to designate the early stages of rot, beyond the typical 
decay or well-advanced rot is of practical value. In some infections 
the incipient decay may end with the typical decay and in other 
cases extend many feet beyond it. The horizontal or radial extent 
normally amounts to only a few inches. Incipient decay, which is 
usually indicated by a discoloration of infected wood, in some cases 
pronounced and in others so faint as to be practically invisible, is 
not always easy to detect. Affected wood in a casual examination 
seems to be firm and strong. Consequently, it is the rule rather 
than the exception in the lumber trade to include incipient decay 
with sound lumber. 

Wood is weakened by incipient decay, the degree depending on 
the stage of the rot and also on the species of fungus at work. Tests 
(3) on Douglas fir with incipient decay of conk-rot showed that the 
wood was apparently not weakened, but pieces with incipient decay 
of red-brown butt-rot and brown trunk-rot, to which general type of 
decay yellow-brown top-rot also belongs, were much reduced in 
strength. Furthermore, if infected material is merely air dried, the 
hyphe may remain dormant, ready to continue to decay the wood 
again if suitable conditions arise. Hence, wood with incipient decay 


16 BULLETIN 1163, U. S. DEPARTMENT OF AGRICULTURE. 


should be excluded from all lumber to be used for purposes requiring 
strength and durability. 

The incipient stage of conk-rot is often quite extensive. In one 
tree this stage of decay extended for 29.6 feet vertically in the heart- 
wood beyond the typical decay, while in several infections this figure 
ranged from 10 to 20 feet. The average extent upward of incipient 
decay beyond the typical decay was 3.3 feet and the average extent 
downward was 4 feet. The significance of this difference will be 
touched upon later. The average extent both up and down was 3.5 
feet, based on 145 measurements. | 

Red-brown butt-rot is less variable in respect to the extent o 
incipient decay. The greatest extent found was 8.4 feet, while the 
average based on 44 measurements was 1.95 feet. This average is 
based on measurements of upward extent only, since most of the 
infections began in the stump or extended into it and no downward 
measurements were possible. 

Only meager data were available on brown trunk-rot. Based on 
13 measurements the upward extent of the incipient decay was found 
to be 3.5 feet, while the downward extent was 3.6 feet. The com- 
bined average was 3.6 feet. The extreme extent was 8.5 feet above 
typical decay. 

The incipient decay of yellow-brown top-rot had an average extent 
upward of 2.2 feet and downward of 3.8 feet, while the combined 
average was 3.1 feet, based on 58 measurements. In one tree incip- 
ew decay extended up beyond typical decay for a distance of 25.4 

eet. 

From the foregoing it can be seen that in all three of the rots in 
which it was possible to make a comparison between the upward 
and downward extent of incipient decay the downward extent 


exceeded the upward on the average, and the difference is most strik-. 


ing in yellow-brown top-rot, where most of the infections occur in 
the upper part of the bole. This difference is probably explained by 
the well-known fact that older trees are much more subject to decay 
than younger ones, and therefore it follows that older heartwood is 
more susceptible than younger. As the fungus progresses downward 
in the heartwood of a tree 1t encounters wood gradually increasing 
in age and easier to decay, while as it moves upward younger wood 
which offers more resistance is continually invaded, decreasing the 
extent of both typical and incipient decay. This tendency for Hee, 
to work more rapidly downward than upward is in keeping wit 
other observations (/, p. 21). 

The figures presented on the extent of incipient decay show that 
this is quite variable and indicate the need for careful inspection to 


eliminate this type of defect from timbers where durability and © 


strength are a prerequisite. 
SUMMARY. 


The four principal decays in Douglas fir are conk-rot caused by 
the ring-scale fungus (Trametes pini), red-brown butt-rot caused by 
the velvet-top fungus (Polyporus schweinitzii), brown trunk-rot 
caused by the quinine fungus ( Fomes laricis), and yellow-brown top- 
rot caused by the rose-colored Fomes (Fomes roseus). Conk-rot and 
brown trunk-rot usually occur in the body of the trunk, red-brown 
butt-rot is commonly confined to the stump and first log, while yellow- 


DECAY IN DOUGLAS FIR. GT 


brown top-rot usually occurs in the upper bole or top. Conk-rot 
causes by far the greatest volume of decay. The other three rots 
are of ie etely minor importance, except that red-brown butt-rot 
predisposes an infected tree to windfall. 

Douglas fir is subject to wounding throughout its life and partic- 
ularly to injury by fire during its earlier years. On the whole, wounds 
in Douglas fir are mostly superficial, and this tree species heals 
rapidly after wounding. Scars callus very irregularly, and it is 
usually difficult or impossible to determine the exact dates when 
scars were made. 

Mechanical injuries are of' little importance in relation to the 
entrance of decay. Knots were responsible for nearly 90 per cent of 
the volume of all decay in the trees studied. Fire scars were the 
entrance point for 4 per cent, and the remaining 6 per cent came in 
through other scars. [ire is the only factor which is controllable, so 
there can be but little reduction in the extent of decay in future 
stands by a reduction in the scars caused by controllable mechanical 
injuries. 

eee aniston of the indications of decay in standing or felled timber 
is of the greatest importance from a practical standpoint, yet this is 
little understood. Branch fans, dead limbs, or burls do not indicate 
decay. Sporophores and swollen knots which develop prolifically 
indicate the presence of conk-rot. After a stand has been fire swept, 
burned-out hollows show where there were sporophores and swollen 
knots. It is also possible to approximate with some accuracy the 
volume of the decay. Conk-rot, on the average, extended approxi- 
mately 20 feet in the trunk beyond the highest or lowest sporophore 
and 10 feet beyond the highest or lowest swollen knot. Sporophores 
of red-brown butt-rot are not common. However, the relative fre- 
quency of fire scars indicates somewhat the relative amount of this 
decay. Churn butts often denote old fire scars. Brown trunk-rot 
is rather difficult to detect in standing trees, but the loss caused by 
this decay is insignificant. This also applies to yellow-brown top-rot. 

Figures on the different rots, giving the extent of incipient decay 
beyond typical decay, show that this is rather variable, thus requir- 
ing careful inspection to obviate the inclusion of wood with this type 
of defect in timbers selected for durability and strength. 


OUTLOOK. 


The work on which the preceding discussion is based is merely pre- 
liminary. More extensive studies are needed to bring out new facts 
and develop still further those already brought out. This should 
aid materially in placing the estimating of Douglas-fir timber on a 
more exact basis. | 

The biggest problems remain unsolved. Our half-formulated ideas 
of control of decay in Douglas fir are based on observation without 
a sound backing of exact data. Furthermore, while it is a well- 
established fact that young stands or second growth are relatively 
immune from decay, it is not yet determined at what age in the life 
of the stand this immunity ceases and the trees become subject to 
extensive decay. Establishing this age will enable us in the future 


18 BULLETIN 1163, U. S. DEPARTMENT OF AGRICULTURE. 


to cut stands before there is any real loss and at the same time per- 
mit the trees to attain the maximum size. 

Equally important is the periodic rate of increase in the loss through 
decay after the above age has been passed. Such information is of 
the highest value to organizations holding extensive stands of mature 
or overmature timber, enabling them to estimate the loss in their 
holdings and adapt plans accordingly. But these questions can only 
be answered by the study of all the trees felled and left standing on 
a wide range of plats in stands of different ages and conditions 
selected on logging operations throughout the Douglas-fir region of 
the Pacific Northwest. 


LITERATURE CITED. 


(1) Boxcz, J. 8. 
1920. The dry-rot of incense cedar. U.S. Dept. Agr. Bul. 871, 58 p., 3 fig., 
3 pls., 11 tables. Literature cited, p. 57-58. 
(2) CHapmMaNn, Herman Haupt. 
. 1921. Forest. mensuration. xxii, 553 p., 88 fig., 89 tables. New York. 
= (8) Coury, R. H. 
. 1921. The effect of incipient decay on the mechanical properties of airplane 
timber. (Abstract.) Jn Phytopathology, v. 11, p. 45. 
(4) MOLuER, A. 
1904. Uber die Notwendigkeit und Méglichkeit wirksamer Bekampfung des 
Kiefernbaumschwammes Trametes Pini (Thore) Fries. Jn Zitschr. 
Forst. u. Jagdw., Jahrg. 36., p. 677-715, pl. 4-5. 
(5) U. 8. Depr. Acr., Forest SERVICE. 
1916. Instructions for the scaling and measurement of national forest timber, | 
94 p., 10 tables. Washington, D. C. 
(6) 1920. Timber depletion, lumber prices, lumber exports, and concentration of 
timber ownership. 71 p., 22 fig., 26 tables. Washington, D. C. 
(7) Were, James R., and Husert, Ernest E. 
1918. A study of heart-rot in western hemlock. U.S. Dept. Agr. Bul. 722, 
39 p., 13 fig. Bibliographical footnotes. 
(8) 1919. A study of the rots of western white pine. U.S. Dept. Agr. Bul. 799, 
. 24 p. Bibliographical footnotes. 


19 


ORGANIZATION OF THE 
UNITED STATES DEPARTMENT OF AGRICULTURE, 


Seeretary of Agriculture. sos 4.8 DO ee Henry C. WALuACE. 

Aasisiant. Secretar us .2- dargwata ied sehamravee C. W. PuaestEy. 

Deretioniof, Scienicfies, Werke, . 3.2% , <7 id tis E. D. Bat. 

Director of Regulatory Work. . 2.2.2 200-+52 004 

TRENT SR AE state Tine deiptR Asi ais legs asteea CHARLES IF, Marvin, Chief. 
Bureau of Agricultural Economics.......----- Henry ©. Taytor, Chief. 

Bureau of Animal Indwmstripass 6.4), ooh sdeewis JoHN R. Monter, Chief. - 

Bapreats af Piaget lenis ole oud 2 Naat Witi1am A. Taytor, Chief. 

PIGPUSTAS CRORE. 5. satus os otha oad eee a W. B. GREELEY, Chief. 

Burcat of Chenvsiry... -o wet ner dee eae WaLTER G. CAMPBELL, Acting Chief. 
PS URCOU-OF MOUIRS 1'0-at aon bia se as eh ee ee Mitton WHITNEY, Chief. 

Bureat of - LriOmowWgy. 2. face. dancin L. O. Howarp, Chief. 

Bureau of Biological Survey.........-------- KE. W. Netson, Chief. 

Bureay of Publie Roads... 0.22 2.t ie eee Tuomas H. MacDona.p, Chief. 
Fixed Nitrogen Research Laboratory.......---- F. G. Corrrety, Director. 
Division of Accounts and Disbursements... ...- A. ZAPPONE, Chief. 

Division of Publications: .22..2... +. Geyeast EpwIin ©. PowE.., Acting Chief. 
Tpibrary: S. sick doll. wks aholeawd. aeigesy CLARIBEL R, Barnetz, Librarian. 
States Relations Service... .2si.e.-2- 1.2.2.2 A. C. True, Director. 

Federal. Horticultural Board . «3.4 «sla -cvteme C. L. Maruart, Chairman. 
Insecticide and Fungicide Board........-.---- J. K. Haywoop, Chairman. 
Packers and Stockyards Administration.....--.. CHESTER MorRILL, Assistant to the 
Grain Future Trading Act Administration... i Secretary. 

Office: of thé Soler. 6A... ctcdess bee peaes R. W. Wiuirams, Solicitor. 


This bulletin is a contribution from 


Bureaw of Pleas Tnaustrys ook sain he Wiiuram A. Tayzor, Chief. is 
Office of Investigations in Forest Pathology. HavEN Mercatr, Pathologist in. 
Charge. : 

20 


ADDITIONAL COPIES 


OF THIS PUBLICATION MAY BE PROCURED FROM 
THE SUPERINTENDENT OF DOCUMENTS 
GOVERNMENT PRINTING OFFICE 
WASHINGTON, D. C. 

AT 


10 CENTS PER COPY 


PURCHASER AGREES NOT TO RESELL OR DISTRIBUTE THIS ; 
COPY FOR PROFIT.—PUB. RES. 57, APPROVED MAY 11, 1922 : 


V - 


Ee ee ee ee ee eS ee ee ele eee 


Te 8 


ee ee a eee fe er 


a, ee ee a a, ee eT 
\ 


— 


=e OF ee es 


ee PP. 


vA 


Washington, D. C. Vv February 8, 1924 


WHITE-PINE BLISTER RUST IN WESTERN 
EUROPE. 


By W. Sruart Morr, Assistant in White-Pine Blister-Rust Eradication, Office of 
Blister-Rust Control, Bureau of Plant Industry. 


CONTENTS. 

Page. Page. 
imireducnen=— Sa. fs 525 2 eke} 1 | Control measures recommended in 
Scope of the investigations________ 2 FCBR OC a a ees Ste I ag ce Ya 17 
istorica | ireviews 222 5. ee 3 | Significance of European experience 
Susceptibility of blister-rust hosts__ 3 EO" AImein Cage) 22 suk. sea uk ee 21 
Relation of white pines to Huropean Economic aspects of the blister-rust 

ROT eetitey seeeetess 2-3 re eee et 6 DrODIGINETeey A eter ee ee 25 
Importance of currants. and goose- Summary of the blister-rust situa- 
Bates Los eee BAO es ee ie 9 tron: in Huropes. 2 2222 474s 26 
Damage to eastern white pine in European experience a warning to 
LOLI Oe a oe ee Ee allel Pa. OOK E GAC GE Vie IR Is cll nl ives ipa ale 28 
hiterature: ‘eited2s2s 22 eee os 29 
INTRODUCTION. 


Following the outbreak of the white-pine blister rust in the north- 
eastern United States and in Ontario, Canada, foresters and patholo- 
gists sought a method of combat, and to this end European litera- 
ture was scanned for assistance (40)*. The European scientists who 
studied the causal fungus (Cronartiwm ribicola Fischer) had con- 
fined their research almost exclusively to its biology. Their inves- 
tigations as summarized in literature contain many suggestions for 
combating the disease, and they advance the principle of control by 
host separation but yield nothing definite on the practical applica- 
tion of control measures suited to American conditions. During the 
period from 1917 to 1921 the United States Department of Agricul- 
ture, in cooperation with the New England States, New York, Wis- 
consin, and Minnesota, conducted extensive experiments to develop 
methods of practical control of the disease under forest conditions. 

These experiments have fully demonstrated that under average 
forest conditions in the northeastern United States, white pine can 


1The serial numbers (italic) in parentheses refer to ‘“‘ Literature cited” at the end of 
this bulletin. 


55162°—24——-1 2 z 


29 BULLETIN 1186, U. S. DEPARTMENT OF AGRICULTURE. 


be effectively protected (10). Control is accomplished by uprooting 
all wild and cultivated currant and gooseberry plants (Ribes) within 
a distance of 600 to 900 feet of the trees to be protected. The de- 
struction of wild currant and gooseberry bushes can be accomplished 
at a cost sufficiently low to make it practicable and profitable to safe- 
guard the valuable white-pine crop of the Northeastern States. In 
the five years from 1918 to 1922 the cost of removing 19,224,118 
wild currant and gooseberry bushes from 1,504,945 acres of forest 
and pasture land averaged 31.8 cents per acre. Any white-pine stand 
protected in this manner is safe from further rust infection for at 
least 5 to 10 years, and in many cases permanently, depending on 
whether or not local conditions are favorable or unfavorable to the 
growth of wild currant and gooseberry bushes. Several years of 
careful study are required to develop and perfect the cheapest and 
simplest methods of control, since many phases of this work are still 
in the experimental stage. Meanwhile, the control measures that 
have been developed should be generally applied at once to prevent 
further losses from this disease. } 

The writer, a forester, observed the blister-rust situation in several 
European countries in 1919 and 1920 and takes this opportunity to 
acquaint others with his observations, which should be of especial 
interest to timberland owners on account of the rapid spread of the 
disease in the Northeastern. States and its occurrence in British 
Columbia and Washington. Unless otherwise specified, the state- 
-ments are based on the writer’s observations. It would have been 
quite impossible to conduct the work without the assistance and 
advice of scientists, departments of agriculture, and forest officials 
in the countries visited. The writer wishes to express his sincere 
appreciation to those who freely gave their time and efforts, which 
contributed so largely to the progress of this work. 


SCOPE OF THE INVESTIGATIONS. 


The primary purpose of this work was to gather information re- 
garding European methods of dealing with the white-pine blister 
rust which would assist in the control campaign in America. To 
accomplish this purpose, plantations of infected white pine were 
studied, foresters and pathologists interviewed, and data compiled 
as to the actual and financial loss caused by the disease. This work 
was supplemented by visiting the nurseries to observe their sanitary 
conditions, in order that a first-hand opinion might be formed as 
to the justification of the rigid quarantine regulations adopted by the 
United States against imported nursery stock. In addition, all 
available historical and biological data concerning the fungus were 
collected in Norway, Sweden, Denmark, Great Britain, France, and 
Belgium. ‘Typical specimens of ornamental white pine were seen 
very frequently in European parks and arboretums (PI. I.). Even 
under the most favorable conditions they become prey for the blister 
rust. 

As the writer was in Sweden during the fall of 1919 and winter of 
1919-20, work was begun in that country and extended to cover 
Norway and Denmark. By the middle of July the field was shifted 
to the British Isles, then to France and Belgium, which were com- 
pleted on November 1, 1920. Miscellaneous notes were also gathered 


WHITE-PINE BLISTER RUST IN WESTERN EUROPE. 3 


by correspondence from other European countries, including Ger- 
many, Switzerland, Holland, and Russia, although these countries 
were not actually visited. 


HISTORICAL REVIEW. 


Both the Peridermium and Cronartium forms of Cronartium 
ribicola have been known in Europe for 65 years. Dietrich first 
used the name about 1856 in a collection of dried plants entitled 
“Plantarum Florae Balticae Cryptogamarum” (//, p. 287), and 
European writers generally attribute the name to him. Five years 
-later, in 1861, W. Saellen discovered the fungus on white pine near 
Helsingfors, Finland. The form on Ribes, as far as is known, was 
not found in that country until 1897 (28, p. 447-449). Rostrup, in 
1865, found the disease in Denmark on black currants, while Kor- 
nicke first found it in East Prussia in 1865 (27, p. 281). It was 
unknown in the rest of Germany until Fischer de Waldheim found 
it on Ribes aureum at Stralsund in 1871.2 The following year 
Magnus found it on the same species at Kiel (29). 

‘The disease was reported on one or both hosts from western Si- 
beria in 1879,3 Sweden in 1880 (14), Norway in 1885 (7, p. 70), 
Holland in 1885 (32, p. 239), France in 1889,* and during the fol- 
lowing decades from the British Isles in 1892 (33), Belgium in 
1894 (37), and Switzerland in 1895 (75). The date 1887 is perhaps 
the most significant in blister-rust history, for in that year Klebahn 
separated the old composite species Peridermium pini Willd. into 
three species, namely, Peridermium pini ribicola Kleb., Peridermium 
cornui Rostrup and Klebahn, and Peridermium strobi Kleb. (22). 

In 1888 Klebahn determined by inoculation experiments the re- 
lationship between the Peridermium form on Pinus strobus and the 
Cronartium form on Ribes. The same year, in company with O. 
Nordstedt at Grimstorp, Westgotland, Sweden, this belief was veri- 
fied when they found white pine and black currants growing close 
together and both badly diseased (22). 

Following the determination of the host plants the fungus has 
been repeatedly found and reported from several European coun- 
tries, attracting the attention of both mycologists and foresters. Its 
distribution covers nearly the whole of western Europe and the 
British Isles and, according to statements by members of the Nor- 
wegian forest service, extends to 634° north latitude on the Nor- 
wegian coast. The date of the introduction of the blister rust into 
America is not known, but circumstantial evidence indicates that it 
was first introduced from Europe about 1898. 


SUSCEPTIBILITY OF BLISTER-RUST HOSTS. 
FIVE-NEEDLE PINES. 


The current European opinion is that the fungus originated on 
Pinus cembra in Siberia, migrated to Europe, and became far more 
virulent on the exotic five-leaved pines than on its supposed original 
host. Contrary to the writer’s expectations, he found no Pinus 


2Rabenhorst, L. Fungi europaei exsicatti, No. 1595. 
’Thuemen, Felix von. Mycotheca universalis, No. 2049. 
Specimen. Natural History Museum, Paris. 


4 BULLETIN 1186, U. S. DEPARTMENT OF AGRICULTURE. 


cembra infected in the countries visited, although a single instance 
of its occurrence on this species is reported from Switzerland (37). 
Besides occurring on Pinus cembra and P. strobus, it has been found 
(and seen by the writer, except as otherwise noted) in Europe on 
other species as follows: P. ayacahuite Ehrenb. (British Isles and 
Belgium), P. excelsa (Denmark, 36, p. 312), P. flexilis (Belgium, 
France, Germany (42), Norway, Sweden), P. koraiensis (Sweden), 
P. lambertiana (Belgium, British Isles, France, Germany (42), 
P. monticola (Belgium, British Isles, Germany (42) ), P. pentaphylla 
(British Isles) ,° and P. peuce (Belgium,’ Germany (42)). 
Inoculation experiments successfully conducted by many European 
investigators show that all five-leaved pines and Ribes tested are 
susceptible to the fungus, though varying greatly in their degree of 
susceptibility. The experiments also prove the independence of the 
two forms Perzdermium pint and P. strobi. It is worthy of mention 
at this point that the earliest known Cronartium on Ribes, though 
not C. ribicola, was collected by Jacquemont (43), the French ex- 
plorer, in India in 1830 and determined by Leveille as Cronartium 
asclepiadeum.® This is particularly significant, since in 1914 a bark- 
inhabiting Peridermium was found on the Himalayan white pine 
(Pinus excelsa) and sent to the Mycological Bureau at Pusa, India. 
Dr. E. J. Butler, of the Bureau of Mycology at Kew, England, kindly 
forwarded a specimen of the Peridermium to the writer, who sent it 
to Dr. R. H. Colley, of the Office of Forest Pathology, for deter 
mination. He found it to be distinctly different from Cronartium 
ribicola. | 
CURRANTS AND GOOSEBERRIES. 


Herbariums in the botanical museums were carefully scanned for 
Ribes species serving as hosts for Cronartiwm ribicola and for the 
localities and dates of occurrence. A total of 29 species was recorded, 
covering all the western European countries. Of the common Ribes, 
the most readily infected is nigrum (41), while grossularia and 
rubrum are less susceptible. The writer found the first-mentioned 
species, but not the last-mentioned, infected in Europe. In the Vil- 
morin Arboretum at Nogent sur Vernisson, Loiret, France, 35 species 
were examined, and only two were found: infected, namely, A7bes 
caucasicum and Ribes propinquum, both of which were badly dis- 
eased. European foresters regard ibes nigrum as the most danger- 
ous species and consider other European Ribes as of little consequence 
as agents for harboring the white-pine blister rust. ~ 


CURRANTS AND GOOSEBERRIES KNOWN TO BE SUSCEPTIBLE. 


The list of varieties shown in Table 1 includes all infected species 
of Ribes seen by the writer in herbariums and elsewhere in Europe, as 
well as those observed by a correspondent, Prof. O. Juel, in 1920, in 
the Botanical Gardens at Upsala, Sweden; but undoubtedly other 
host species exist in other European collections. 


5 Correspondence with Professor Von Tubeuf, 

6 Reported by the Forestry Commission for Scotland. 

7 Reported as having occurred at Groenendael, Belgium. . 
8 Specimen in Cryptogamic Herbarium, Botanical Museum, Paris. 


Bul. 1186, U. S. Dept. of Agriculture. PLATE |. 


A CENTURY-OLD WHITE PINE IN BELGIUM. 


This magnificent specimen in the Domaine of St. Ode, Luxembourg, is one of our finest American 
trees on foreign soii. Photographed by Prof. Charles Bommer, Brussels, Belgium. 


Bul. 1186, U. S. Dept. of Agriculture. PLATE Il. 


A GRouP OF 70-YEAR-OLD WHITE PINES IN BELGIUM. 


The largest tree in this group, at the farm St. Michel, near St. Hubert in the western Ardennes, in 
1902 measured 110 feet in height, with a diameter of 33 inches at breast height. This tree would 
cut 1,400 board feet, valued in Europe at approximately $0 per thousand on the stump. 
Photographed by Prof. Charles Bommer, Brussels, Belgium. 


WHITE-PINE BLISTER RUST IN WESTERN EUROPE. 5 


TABLE 1.—List of species of Ribes infected with blister rust as seen by the 
writer in certain herbariums and elsewhere in Hurope and by Prof. O. Juel in 
the Botanical Gardens at Upsala, Sweden. 


[Names recorded from the specimen labels are shown in boldface type. The synonymy 
has been furnished by Dr. Frederick V. Coville, and the synonyms are here printed 
in SMALL CAPITALS. Doctor Coville believes that the gooseberries are more satisfac- 
torily regarded as belonging to Grossularia, a genus distinct from Ribes, which com- 
prises the currants. The species are_so treated in the revision of the family Gros- 
sulariacee in the North American Flora (9). American species or varieties are 
designated by an asterisk (*). Hxpianation of symbols.—Bru=Botanical Museum, 
Brussels, Belgium; Chr=—Botanical Museum, Christiania, Norway; Cop—Botanical 
Museum, Copenhagen, Denmark; Lon=British Museum, London, England; Sto—Royal 
Museum at Stockholm, Sweden (contains the herbariums of Rehms and Sydow, as 
well as those of Swedish collectors; Upsala—Botanical Gardens, Upsala, Sweden; 
Vil=Vilmorin Arboretum, Nogent sur Vernisson, Irance.] 


Name of species. Where seen. Remarks. 
Seen by the writer: ; 
albidum* L....-...-.-- WOH sae resn ek estate se « This presumably is Ribes albidwm Paxton, which 
is an albino form of #. glutinosum Benth. 
alpinum Ll... -.------ ChrseonheuOs-2. + 40s... 
SES eae ee ee See floridum. 
apiifolium......-.-.-- WonyS tose wik eh. sans Ss: According to Janczewski (22) this is a hort:- 
cultural variety of R. nigrum L. 
-atropurpureum Mey)|..... GOs as teased fk. According to Janczewski this is a variety of 
RK. petraeum Wulf. 
aureum* Pursh.....- ChniCop; duon7Stor .3--5 This is probably R. odoratum Wendl., the com- 


mon very sweet-scented golden currant of 
gardens which often passes under the name 
Fk. aureum Pursh, a related species seldom cul- 
tivated and with little odor. See also ginkae= 
folium and tenuiflorum. 
caucasicum......... Nile ie ied Sates eek ot Listed as holosericewm No. 7432 in Vilmorin’s 
/ catalogue. This is probably R. holosericewm 
Otto and Dietr., a hybrid of R. petraeum and 


R. rubrum. 

eynosbati* L......-.- WOM Aa Sabe o ce eis oil soot fee gracile. 

Oy ISTE TEE ES |e ee ee Cee saxatile. 

floridum* [L’Her....- One maiiarisete Aten do. The name FR. jloridum L’Her., published in 1785, 

5 isasynonym of the much older R. americanum 

Mill., published in 1768. 

fontanesii* Colla..... JOOor Sila Ree eee ee ae ee The name #. fontanesii Colla is a synonym of 
R.odoratum Wendl. 

ginkaefolium*.......|..... ClO eS Se eae a ieres This is presumably a form of R. aureum cata- 


logued for many years by Spaeth, a Berlin 
nurseryman, under the name F&. aurewm gink- 


gifolium. 

Grotmosum bern. .|_-.- 2. ....-5---»- Saew = See albidum. 

gordonianum* Lem.) Lon, Sto............-....-. This is a well-known hybrid between R. odoratum 
and I. sanguineum. 

gracile* Michx........ SOLS ee eee Michaux’s Ff. gracile is a smooth-fruited form of 


R. cynosbati L., but the plant that usually 
passes under the name R. gracile is R. mis- 
souriense Nutt., the Missouri gooseberry. 


grossularia [.......-- Bru, Cop, Lon, Sto.-..-... 
heterophy!llum Phil.| Lon, Sto.-................ According to Janczewski this is a variety of R. 
punctatum Ruiz. and Pav. 
HOMsOHBIOMUNE MOTO poe nf). 25 od oeiecch cece emt See caucasicum. 
and Dietr. 
intermedium Tausch; Lon, Sto.................. According to Dippel FR. intermedium is a hybrid 
between Rk. americanum and R. nigrum. 
longiracemosa Wil- |...........------.----.---.- Inoculated by Prof. W. Somerville, of Oxford. 
son. 
macrobotrys fuiz | Lon, Sto.................. 
and Pay. 
menziesii* Pursh.....)..... So mpl gine A aa This is a well-known gooseberry of southern 
Oregon and northern California, but the name 
has often been misapplied to other Pacific coast 
species. See subvestitum. 
missouriense* Nutt.|..... Os eaciaseeiten oxo t 0h: 
Migrumy U2. 2--2:-2-- Bru, Chr, Cop, Lon, Sto...| See also apiifolium. 
niveum * Lindl..-..... Pon Stoufes2 sa ea 2.2 
PDR EMV CTO colo cis a ac woe wine Sele Hino jee n= See aureum and fontanesii. 
orientale Desf.......- TOUS SCOM SS6 sot et. 3k 
oxyacanthoides* L..)..... (tee ia a 
parvifolia * Phio.....|....- COm eee eee et. Sk .| This should be parvifolium Phil. 
petraeum Wulf...... COON StOs. 5823 32 MEERELK . 1 See also atropurpureum. oh 
Propmaguium hure7zs) Vil... ..2.......2.--<e- Sue to Janezewski this is R. warszewiczii 
ancz. 


RUC ATMEL RUIZ, ATG, |e 8 2 ol oo oe ale = oar oe ee See heterophyllum. 
Pav. mi 


6 BULLETIN 1186, U. S. DEPARTMENT OF AGRICULTURE. 


TABLE 1.—List of species of Ribes infected with blister rust, ete.—Continued. 


Name of species. 


Seen by the writer—Con. 
racemosa Wilson. ee 


sanguineum?* Pursh. 


Where seen. 


Remarks. 


Bris Cop .StOu Ste sees 
Lon, St 


Inoculated by Prof. W. Somerville, of Oxford. 


Saxatile:Pall .....°s2252.|paees GOS... sashes os Ae ieee This is R. diacantha Pall. 

setosum * Lindl.....|..... DOzews 5 ists alt gee 

subvestitum *.......]..... Cones tot ie Lee: The original R. subvesiitum published by Hooker 
and Arnottisasynonym of R. menziesii Pursh., 
but other Pacific coast species of gooseberry 
have sometimes passed under the name of R. 
subvestitum. 

tenuifiorund-Lind): 23) “ones a. 220. i. a. eee This is a synonym of R. aurewm Pursh. The 
name has sometimes been misapplied to R. 
gracillimum Coville and Britton. 

WARSZE WICZIT Jane7d.c\lieecoce see. Sele eee See propinqguum. 

Seen by Prof. O. Juel: 

americanum * Mill..| Upsala.................... 

aureum * Pursh.....|..-.- GOs ct en = Su). See 

biebersteinii Berl....|..... COASISSSEAM See This is regarded by Janczewski as a variety of 
Rk. petraceum Wulf. 

divaricatum * Dougl.!...-. GOS 2 oc: Berar: 

divaricatum var. |..... dO: oo. tesa This is probably intended for divaricatum var. 

glabrifolium. glabriflorum Koehne, a smooth-flowered form 

of R. divaricatum Dougl., a common northwest- 
coast gooseberry. 

gordonianum* Lem.|..... GOSS SOS eee 

INERME Rydberg......|...-. 10%. Sou Rae ase a eae See oxyacanthoides nevadensis. 

multifiorum Kit.....|..... 05 fs Mareen es eet thoes egy 

nigrum 25. es pense QD: DEAE, 

orientale Desf_......_|....- OLA. bs 5 See a oes ; 

oxyacanthoides |..... 0. SS ee ete oe eee This is R. inerme Rydberg, the wine gooseberry. 

nevadensis.* 

PETRAEUM Wulf. = oe|scsee dO: ee ee fe See biebersteinii. 

pinetorum * Greene.|....- 0: See ee ee 

pubescens Sw........|.-..: GO: J keeoenee ec ae This is doubtless R. rubrum pubescens Swartz. 

TUPI Tee oe | ee QDs Sete eee pe oe See also pubescens. 

sanguineum* Pursh.|....- GOsc2 ee Pee Ses 

bie de Mert. and |..... GOs 82. 2 abe Re ee Thisis a synonym of R. vulgare Lam. 

och. 
VULGARE Lam. 4. oes eee GOR Yi se De eee See sylvestre. 


RELATION OF WHITE PINES TO EUROPEAN FORESTRY. 


Kuropean forest conditions form a striking contrast to those in 
America. In Europe conservative methods of management and 
utilization have been in practice for centuries, whereas in America 
we are considering only the ways and means of applying such 
methods. Labor costs, though now abnormally high in Europe, as 
elsewhere, have usually been very low, a factor which has con- 
tributed largely to the success of forest practice abroad. With the 
development of forestry as a science, exotic tree species have been 
sought for study and experimental planting. There has been a 
continual search for species which would become readily naturalized 
and establish themselves under different conditions of planting and 
site. Trees from the New World were eagerly sought after, both 
for ornamental and forest planting. Many of the newcomers soon 
found a permanent place in the list of desirable species for use 
by the arboriculturist and the forester, foremost among which was 
Pinus strobus. 

In Europe the eastern white pine of North America (Pinus 
strobus) is invariably called “Weymouth pine.” According to 
Belon (S) this tree was growing in the royal nurseries at Fon- 
tainebleau, France, in 1553. If that is true, it is the earliest record 
of its appearance in Europe. It was not until after its introduc- 


. 
| 


WHITE-PINE BLISTER RUST IN WESTERN EUROPE. 7 


tion into England in 1705 and later into other European countries 
that the tree became prominent abroad. From the beginning its 
distinct and ornamental beauty interested foreigners (Pls. I and IT). 
Gold and silver medals were offered for plantations of Weymouth 
pine in England by the Society for the Encouragement of Arts in 
1765 (1). This tree is now well known abroad and is one of the most 
widely distributed of introduced American species. Unfortunately 
in several countries Cronartium ribicola has taken such heavy toll 
that some foresters are wary of planting it, while others have abso- 
lutely discontinued its cultivation. 

White pine although widely distributed is not the commercially 
important forest tree in Europe that it is in America, for it is not a 
native species. The total area which it occupies is negligible in com- 
parison with the forested areas of European countries. The ease 
with which the wood can be worked and its varied uses for joinery, 
pattern making, matches, and in shipbuilding for masts, yards, and 
deals brought imported white pine into much demand abroad. <Ac- 
cording to Laslatt, timber inspector of the British navy, when ships 
were built of wood “white pine served well for masts and bow- 
sprits,” but he says it was not strong enough for hight spars subject 
to great and sudden strain. For such requirements it was surpassed 
in strength and durability by Oregon fir (25, p. 356-366). 

To-day in Europe it is difficult to obtain white pine free from 
knots and sapwood. In England the value of the best quality is 
advanced to 6s. ($1.50) per cubic foot. During the war the timber 
controller fixed the maximum price at 9s. 8d. per cubic foot, or 
approximately $389.75 per thousand board feet (20). 

Standing white pine has brought equally high prices. A 70-year- 
old plantation cut in Surrey during the war yielded a clear profit of 
$340 per acre. In the Vosges region of France 60-year-old planta- 
tions on optimum sites have yielded 68,590 board feet per acre, with 
a stumpage value of $44.53 per thousand board feet. Other planta- 
tions near Epinal in the French Vosges at the age of 55 years have 
produced a volume of 42,900 board feet per acre (fig. 1). In Ger- 
many, pure stands 104 years old yielded 81,538 board feet per acre, 
while stands 68 years of age produced 61,560 board feet per acre (44). 

In volume production and rapidity of growth white pine ranks 
high. In the Vosges of France at 60 years it has shown a mean an- 
nual growth of 190 cubic feet per acre, a figure which has been 
equaled in Belgium. At Oxford, England, at 12 years the yield was 
181 cubic feet per acre. It was outclassed in mean annual volume 
production by Douglas fir (Pseudotsuga taxifolia) from Vancouver, 
western hemlock (7'suga heterophylla), western red cedar (Z’huja 
plicata), and Sitka spruce (Picea. sitchensis). The diameter growth 
of white pine, however, was good. Trees 12 years old with 3.2 inches 
average diameter at breast height were exceeded only by Vancouver 
Douglas fir with an average diameter of 3.4 inches (38). 

A recent Belgian publication (76, p. 14) states that the only merit 
of white pine from its viewpoint is its large volume production 
and that its reputation as a tree with a future in Belgium has been 
overestimated. Bommer and Visart, on the other hand, credited 
white pine with being the one pine which up to the present has been 
cultivated successfully on the high plateau of the Ardennes (6). In 


8 BULLETIN 1186, U. S. DEPARTMENT OF AGRICULTURE. 


1911 an English writer said that the blister rust caused much damage 
to young trees, and it was not valuable enough to plant as a forest 
tree except on a small scale (17, p. 173). Similarly, Baltz in Ger- 


. 


¥ 


. % sad iy : 
Md a : 4 ’ x we ix * ae ; f 


Mens wee fw 


p 


a 
a, 

‘ 

rh bere 

ih Chew. 


se at: + calla ae 


ie 
, 
- 
t 


Rx. Bd 


usb 
Rie f 


re nae . he 
Mi : 
od : " 
ek igs” 


ae 
“a 


vase eh SRA : 
iid QP sA)! Dares: 
ee ee i ee wey 
a 
rth seme 
i SR Re ee le 
aa 
et cor’ Sa 


mee , 


Pike Bees ewe, ae 


, 
a 
o* 


pee Ss alata 3 spiaigttc: FE 
Siig Salata, F 
PRBS 


Fig. 1.—A 55-year-old white-pine plantation in the French Vosges, yielding 42,900 board 
feet per acre. Note the clean straight trunks of the trees. Such a crop is profitable, 


and there are many stands similar to this in the white-pine regions of northeastern 
America. 


many suggested caution in planting white pine on.a large scale (4). 
Henceforth, owing to the destructive power of the blister rust, white 
pine will be planted commercially less and less in Europe. 


; 


WHITE-PINE BLISTER RUST IN WESTERN EUROPE. 9 


Other members of the American five-leaved pine group have been 
introduced into Europe, but only for ornamental and experimental 
planting. The sugar pine (Pinus lambertiana), the most valuable 
commercial timber tree on the Pacific coast, was introduced into 
England by Douglas in 1827 and later into other European coun- 
tries. The western white pine (Pinus monticola), since its introduc- 
tion into England by Douglas shortly after 1831, has been planted 
here and there in the British Isles and European countries as an 
ornamental tree (72). The limber pine (Pinus flexilis), a native of 
the Rocky Mountain region, has been planted scatteringly in Europe 
for ornamental and experimental purposes. Specimens are to be 
found in the British Isles, Belgium, France (fig. 2), Norway, Swe- 
den, and Germany, but there are no extensive plantations. Others 
more rarely found are P. albicaulis, P. balfouriana, P. monophylla, 
and the Mexican white pine (P. ayacahuite). These trees have no 
commercial future in Europe, but are valued and sought continually 
for park and arboretum planting by tree enthusiasts. The Him- 
alayan white pine (Pinus excelsa) and the Balkan white pine (Pinus 
peuce), both five-needle species, indicate favorable growth possibili- 
ties combined with more or less resistance to Cronartium ribicola 
and will undoubtedly become more popular abroad for forest 
planting. 


IMPORTANCE OF CURRANTS AND GOOSEBERRIES. ~ 


Currants and gooseberries are universally grown in the cultivated 
areas of western Kurope and are far more extensively used abroad 
than in this country, fulfilling many demands, such as making jellies, 


jams, pastries, and wine. Black currants (/’zbes nigrum) generally 


predominate, although red currants, gooseberries, and ornamental 
species are common. Wild Ribes are usually limited to five species, 
R. rubrum, 2. nigrum, PR. grossularia, Rk. alpinum, and PR. petraeum. 
In several countries only the first four occur, but not abundantly. 
This scarcity, however, is more than compensated for by the presence 
of the cultivated bushes, which are everywhere valued as a small fruit. 
Some 35 varieties of Ribes nigrum are described in the fruit cata- 
logue of the Royal Horticultural Society. 

Currant bushes frequently form the principal ornament in some of 
the gardens of European country cottages, and it is often customary 
to train the bushes against the walls of the house. There are nearly 
200 varieties of gooseberries, including yellow, green, white, and red, 
which are made into jams and jellies. The wine made from the best 
yellow gooseberries has a flavor resembling champagne. Single 
gooseberries have weighed as much as 175 ounces (troy weight). At 


‘Duffield, near Derby, England, a bush 46 years old had a circular 


spread of 12 yards, and bushes at Chesterfield, England, trained 
against a wall, measured 50 feet from one extremity to the other (3). 

The northernmost point at which Ribes rubrum grows is near 
Hammerfest, Norway, some 300 miles above the Arctic Circle. Other 
species, as 2. nigrum, Rf. grossularia, and PR. alpinum, are also found 
growing above the Arctic Circle.® Ribes species are essentially 
adapted to a cold moist region, and in Europe they usually do not 


® Notes from the Botanical Museum, Christiania, Norway. 


55162°—24 2 


10 BULLETIN 1186, U. S. DEPARTMENT OF AGRICULTURE. 


thrive in a warm dry climate. This distribution is well illustrated 
in France, where both wild and cultivated bushes are confined to the 
northern part of the country and the cooler regions in the vicinity 
of the mountains to the east and south. They do not occur in cen- 
tral France (24), where the climate is warm and dry. The Ribes 


Fig. 2.—Limber pine (Pinus flexilis) of western North America, growing in the National 
Arboretum at Nogent sur Vernisson, Loiret, France. This tree, although thriving 
under its new surroundings, was attacked by the blister rust on two limbs, one located 
2 feet and the other 4 feet above the ground. 


of India, eight species in all, do not grow in the hot and dry areas, 
but in the Himalayan region (79) at altitudes between 7,000 and 
13,000 feet. The Ribes distribution of the North Temperate Zone 
coincides closely with that of the five-leaved pines, affording optimum 
conditions for the development of the blister rust, 


WHITE-PINE BLISTER RUST IN WESTERN EUROPE. Bl 


The universal cultivation of black currants in western Europe, 
although red currants and gooseberries are also grown, is the primary 
cause of the widespread distribution and seriousness of the disease 
in these countries. White pine is of less importance to the happiness 
and welfare of the average European than are these popular Ribes 
fruits which have been so carefully cultivated for centuries. For- 
esters have found a substitute for white pine in other fast-growing 
conifers, but no fruit to replace the currant and gooseberry. On 
account of the blister rust white pine can not be cultivated further at 
a profit, and the forester must respond to the popular demand to give 
up the exotic white pine rather than require the farmer and gardener 
to forego a profitable and widely grown crop. An excellent example 
of the damage done to white pine by the blister rust when black cur- 
rants are near by to spread the fungus is shown in Figure 3. 


DAMAGE TO EASTERN WHITE PINE IN EUROPE. 


The earliest observation of damage to Pinus strobus by Cronartium 
ribicola is recorded by Hisinger in Finland, 1869 (78), who states that 
30-year-old trees attacked on both the stems and limbs were being 
killed by the rust. Prior to 1870 the fungus had been reported in 
Denmark and later became so widely spread that in several places 
the cultivation of Pinus strobus was abandoned (27, p.281). During 
succeeding years the fungus was discovered in other European coun- 
tries, causing damage and killing trees. Information upon the sub- 
ject is fragmentary, as no accurate records or data have been kept. 
Only meager notes were made concerning the occurrence of the fungus 
and the killing of the trees. It is quite natural that the European 
foresters should not regard the disease in the same light as American 
foresters, since, as previously stated, white pine is an introduced 
- species of secondary economic importance. The fact that the tree is 
susceptible to the rust is sufficient in most cases to create prejudice 
against its further planting. 

SWEDEN. 


The general opinion expressed by the members of the forestry pro- 
fession and of the Swedish experiment station is that the white pine 
is not adapted for planting in their country. The blister-rust attacks 
have been a potent factor in developing this attitude, for the pine has 
become infected wherever planted. A forester in northern Sweden 
states: “Pinus strobus is not a tree for my forest. It is quite impos- 
sible for me to raise it, for Cronartium ribicola {white-pine blister 
rust | causes great loss, particularly to young trees.” Similar state- 
ments have been received from other parts of the country. 


NORWAY. 


Norwegian foresters have held white pine in very high regard be- 
cause of its rapid growth and yield capacity, as well as its ability to 
regenerate naturally. To-day their attitude is very unfavorable, be- 
cause of the destruction caused by the rust in their plantations. The 
Norwegian forest service has not used the species in its experimental 
plantations for several years and henceforth will not cultivate it. 
The few plantations made in the past have been thinned out by the 
disease until only a few white pines remain in the whole country. 


12 BULLETIN 1186, U. S. DEPARTMENT OF AGRICULTURE. 


One small 28-year-old experimental plantation at Jelsa had 100 per 
cent of the trees attacked by the blister rust and 6 per cent already 
pare he None of the remaining trees will make merchantable 
timber. 


Fig. 3.—A white-pine tree growing near black currants at Bagley Wood, near Oxford 
England. This tree illustrates the typical appearance of white pines in a 12-year-old 
plantation in which 95 per cent of the trees are attacked by blister rust. Hach limb 
shown here, as well as the trunk, is diseased. 


DENMARK. 


The white-pine blister rust has been known on the island of Born- 
holm, Denmark, since 1890, when Rostrup collected the first infected 
twig at Almindingen.?® Since that date the disease has become preva- 


10 Pathological collection, Royal Agricultural College, Copenhagen. 


> piaat 


aur 


1,060 trees 20 to 30 


la hana a i i lik a ie i i in i nt i ee ee ee ee Lay Le Bre aE ey en ye eee 


WHITE-PINE BLISTER RUST IN WESTERN EUROPE. 13 


lent in plantations, doing such serious damage that the foresters 
have stopped planting the species. In one pine plantation in the 
Almindingen forest 91 per cent of the trees 20 to 30 years old have 
been attacked by the rust, and it is estimated that 75 per cent will 
be a total loss in 10 years, disregarding the probable damage from 
further infection. No merchantable product will be obtained, and 
the only revenue to be derived is from the sale of wood cut for fuel 
from the dead and dying trees, which barely covers the cost of cutting 
and is insufficient to pay for the original cost and maintenance of the 
plantation. The piling of the tops of white-pine trees felled because 
they were dead or 
dying from the blister 
rust and salvaged for 
fuel is illustrated in 
Figure 4. 

In another pure 
stand of 24-year-old 
white pine, covering 
16 acres, 90 per cent of 
the trees were at- 
tacked, and it is esti- 
mated that in 10 years 
82 per cent of the trees 
will be dead. Out of 


years old examined in 
the Almindingen for- 
est 90 per cent were 
diseased, and it is esti- 
mated that 18 per cent Fic. 4.—Salvaging the dead and dying white pines fol- 


will be dead in 10 lowing a blister-rust attack on the island of Bornholm, 


Denmark. The tops and limbs, as well as the stems, 
years. These figures are piled into cubic meters and sold for fuel. 


represent the condi- 

tions in the entire stand. Thé actual loss can not be determined, 
because many diseased trees have already been cut. The typical 
condition of the white pines on the island of Bornholm, Denmark, 
where the destruction by the blister rust has been complete, is shown 
in Figures 5 and 6. The Danish foresters have a peculiarly de- 
scriptive term which they apply to the white pine. Their name for 
this tree is “ Weymouthsfyr,” but they commonly speak of it as 
“ vemodsfyr ” or the “ melancholy pine,” and this aptly expresses its 
appearance after it is attacked by the blister rust. 

In the Corselitz forest, located in the northeastern portion of the 
island of Falster, the blister rust has so badly damaged the white-pine 
plantations that the cultivation of the species has been discontinued. 
Oak, a more profitable crop for this forest, is being used in some 
cases to replace the white pine (PI. IIT). 


BRITISH ISLES. 


The damage to white pines in England has been serious. <A study 
of a 12-year-old plantation at Bagley Wood, Oxford, revealed so 
much injury inflicted by the blister rust during the early life of the 
stand that it will be impossible to obtain timber of commercial value 
from the plantation. The occurrence of the disease here is interest- 


14. BULLETIN 1186, U. S. DEPARTMENT OF AGRICULTURE. 


lic. 5.—Interior of a 24-year-old white-pine plantation at Almindingen, island of Born- 
holm, Denmark, showing the destruction caused by the blister rust, which has killed 
32 per cent of the trees. The rest are dying from the disease. 


ing, in that it showed a decrease in the amount of infection with the 
increase of the distance from Ribes to pine. Within 200 feet of the 
Ribes bushes (18 black currants, 3 red currants, and 7 gooseberries) 
95 per cent of the trees were diseased (fig. 7). Farther away, at 570 


Fic, 6.—Exterior view of the plantation shown in Figure 5. Even the trees showing 
the best height growth are badly diseased, 


WHITE-PINE BLISTER RUST IN WESTERN EUROPR. 15 


feet, it had decreased to 10 per cent, and at 1,096 feet no disease what- 
ever was found. 

In the Windsor Park forest at Surrey, 67 per cent of the white 
pines, approximately 20 years old, were attacked by the blister rust. 
Of these, 17 per cent had been killed and 25 per cent were in a dying 
condition. ‘This plantation was made in mixture with Pinus syl- 
vestris and other conifers, and the loss due to the disease is perhaps 
less than it would have been if the plantation had been purely Pinus 
strobus. 

In 1896 Pinus monticola was observed to be fatally diseased in 
Scotland (26). A few years later some fine old trees were felled be- 
cause of the damage inflicted by the rust. Hereafter in the British 
Isles white pine must be planted with caution and never in the vicin- 
ity of black currants, as has been the custom in the past. I+ will be 


Fic. 7.—A 12-year-old white-pine plantation at Bagley Wood, near Oxford, England, 
in which 95 per cent of the trees are attacked by the blister rust and 84 per cent are 
in a dead or dying condition, within 100 feet of where 18 black-currant bushes were 
growing. 


well also to plant white pine in mixture with other conifers, rather 
than pure, in order to provide all possible protection from the screen- 
ing afforded by other trees. 


FRANCE. 


French foresters minimize the menace of the blister rust to their 
white-pine plantations and maintain an optimistic viewpoint, because 
the old trees on a casual inspection do not appear to be seriously in- 
jured. This is not true for the young age classes. As far as could 
be learned, the disease has been known on pine in that country only 
since 1890 (34, p. 342). Itis present and destroying natural reproduc- 
tion in the Vosges district, where the writer found clumps in which 49 
per cent of the regeneration was diseased (fig. 8). After the felling 
of the mature stands the damage will be more striking in the young 
growth. If new plantations are made the disease is certain to attack 
them severely before they are 15 years old; that is, assuming that the 


16 BULLETIN 1186, U. S. DEPARTMENT OF AGRICULTURE. 


Ribes bushes are not removed as an act of protection, which seems 
quite unlikely. Plate IV shows a 50-year-old tree in the communal 
forest near Epinal, France, killed as a result of severe crown infec- 
tion by blister rust. Inspection of wind-thrown trees in another sec- 
tion of the same forest revealed many infections and conclusively 
proved that no tree is too large to be attacked and killed by this 
disease. 


BELGIUM. 


The damage in Belgium has been large, but few detailed data are 
available as to the actual extent of destruction. At one time the 
future of white pine in that country was regarded as particularly 
bright because of the success with which it had been grown in the 
Ardennes. In fact, it is the only pine which has been successfully 


Fic. 8.—Natural regeneration of white-pine trees 3 to 15 years old which haye grown 
in an opening made in the overwood of pine and spruce. In a sample plat 25 feet 
square 49 per cent of the trees were infected with blister rust. Diseased twigs are 
marked with pieces of paper, and the tree with the cap on the trunk is dying. 


cultivated in the high plateaus of that region. This opinion has been 
altered, owing to the damage done by blister rust. In an 18-year-old 
plantation studied by the writer, 50 per cent of the trees have been 
killed and 53 per cent of those remaining were diseased. ‘The forester 
in charge of another severely infected plantation said he considered ~ 
it. best to destroy the entire lot and replant with another species, since 
the white pine could not be grown to commercial size. In the opinion 
of the Belgian forest service it can not afford to plant the tree ex- 
tensively because of its susceptibility to attack and damage by Cro- 
nartium ribicola. 

The figures in Table 2 accompanying were obtained from studies 
made in typical infected white-pine stands for the purpose of show- 
ing the average diseased condition of the entire plantation. They 
illustrate representative conditions in the countries visited. In most 


Bul. 1186, U. S. Dept. of Agriculture. PLATE III. 


REMNANT OF A 20-YEAR-OLD WHITE-PINE PLANTATION, CORSELITZE, 
DENMARK. 


Each of the 200 remaining trees is diseased with blister rust on the stem or limbs or both. The 
most severely infected trees have been felled. Those left are now used as a cover crop for the 
pedunculate oak, Quercus pedunculata Ehrh. As soon as the oak becomes well established all 
the white pines will be cut. 


Bul. 1186, U. S. Dept. of Agriculture. PLATE IV. 


aon, + 3 a ; * ie 
»  fenrtle GPs ak me, 
i” abe! Spa 7% bP og a: 
a ia ae Sie ee 

J : :* ‘ee oe 


WHITE PINES IN A COMMUNAL FOREST NEAR EPINAL, FRANCE.. 


The 50-year-old tree bearing the cap has been killed by the white-pine blister rust, while other 
trees in the opening in the background have serious crown infections. 


WHITE-PINE BLISTER RUST IN WESTERN EUROPE. We 


cases the site chosen for the plantation was favorable to the growth 
of white pines. The Windsor Park woods, England, were too sandy 
for its best development, and the location at Almindingen, island 
of Bornholm, Denmark, was too wet. 


TABLE 2—Summary of typical European conditions with respect to the infec- 
tion of pine trees with blister rust. 


Black currant 
(Ribes nigrum). 


White-pine (Pinus strobus) trees examined. 


Area Attacked | Killed by | Dying from 


Country and locality. |stud- A by rust. rust. rust. 
ied. ate” ee Distance from |Num- 
: er. ines. ber. 
height. Num-| Per |Num-| Per [Num-| Per x 
ber. | cent. | ber. | cent.| ber. | cent. 
England: Acres.| Feet. Feet. 
(Os, 3010 (eee eee 2 20.) ar 105 954 aL Pig 73 | 65.7 190 18 
Windsor Park..... 25 25 | 394 67 | 17 17 | 4.3 17 | 4.3) 1,760 to 4,600 100 
Norway: 
Jelsaaorssth*, 27} 14 35 159 159 | 100 107 | 67 b2 |¥o2 150 10 
Fjosanger.......... 1 25| 20] 20] 100 5 | 25 15 | 75 500 12 
Sweden: 

Atvidaberg........ al 30 30 Dae Ooo 8.a: «stall etarelarats 3 | 10 3,500 150 
gists 15 0} 517 4) 90 168 | 32 184 | 33 820 15 
sya 2 46 2 

Almindingen. ..... 16 351 543 | 493] 91 94 | 17 245 | 45 3,000 50 

France: 

Lesbarres.......... 5 15 31 5 LG Poee teed sate 4) 13 1,600 35 

: 4 --10 63 31} 49 fr ec al Sos! eee 2,500 30 

La Mouche, Epinal { 6 bo | 2995 (2-296. (2i.. 21: Ee Pal sc 27500} 30 

Ste Oreie oto. os 2 “f 135 26} 19 ae] bear Saal Sores eee oe 3,300 10 

Deyvillers......... 2 18 89 42 | 47 LON Ee, ellie Be cael Sralaiave 870 10 
Belgium: 

1 25 41 Dsl OO teal raise castle loleeiote 19 | 46 3, 160 3 

Gedinne........... 43 20 62 62 | 100 6; 9 51 | 80 524 5 

2 12 37 21 FPA) Sc a Perea |e eh ee 430 15 


Total or average.| 864 21 |2,307 |1,574 | 68 438 | 19 670 | 29 1,653 to 1, 843 493 


The European situation may be briefly stated as follows: The 
white-pine plantations in some countries are disappearing as a re- 
sult of the damage by the rust, and foresters quite generally express 
the opinion that the loss resulting from the disease is too large to 
permit raising the species at a profit. The white-pine plantations 
are being replaced by other foreign conifers of good growth rather 
than protecting them by destroying the Ribes. 


CONTROL MEASURES RECOMMENDED IN EUROPE. 


When foresters and pathologists recognized the damage being 
done to the white pine by the rust they began to consider means of 
combating it to save their plantations and ornamental trees from 
destruction. Although in Europe the white pine is an exotic tree, 
Cronartium ribicola is believed to be a native fungus indigenous to 


Siberia. The exact reverse of this condition applies to the United 


tates, where the fungus is rapidly becoming too well naturalized 
in its new environment. 

For at least 30 years European writers have recommended meth- 
ods of control, though rather indefinitely, and have even proposed 
curative treatment for infected trees. The writer found that con- 
trol measures were rarely put to a practical test. The seriousness of 
the disease is fully realized, and its life history is well known, but 


18 BULLETIN 1186, U. S. DEPARTMENT OF AGRICULTURE. 


it took some years for it to become sufficiently well established to | 
attract much attention. The most effective control method, con- — 
sisting of Ribes extermination in the neighborhood of white- -pine | 

plantations, has seldom been practiced. Popular opinion favors sav- _ 
ing the black currants rather than the exotic white pine, because — 


the people have a greater appreciation of their native currants than 


of a foreign tree. 
| SWEDEN. 


Among the earliest recommendations for control are those made by | 


Prof. Jakob Eriksson in Sweden in 1890 (13). He informed the 


writer that the control of the fungus by the removal of the Ribes — ; 
had not been undertaken in Sweden. For some years white pine — 
had been grown in nurseries at Djurgarden, Stockholm, but its cul- — 


tivation was stopped in 1897 because of the increasing loss from 


Cronartium ribicola. At least 50 per cent of the seedlings between g 


the ages of 3 and 5 years became diseased. All such infected stock 
was pulled out and burned, and Professor Eriksson gave orders that 


no white pine from the nursery was to be shipped to other parts of 


the country. 


Black currants and gooseberries were grown near the white-pine ~ 


beds, the former species showing severe infection annually. The 
significant feature is that the cultivation of white pine ceased, while 


that of Ribes continued. A few old trees planted in the park at 
Djurgarden early in the nineteenth century became infected in the — 
crown and on the side limbs. These trees were carefully treated by — 
removing the diseased limbs, so that to-day they still survive, al- — 
though somewhat lacking in natural symmetry because of the prun- — 


ing away. of the infected branches. 


NORWAY. 


A Norwegian writer, Schgyen, in 1895 recommended growing the 
Ribes and pine apart from each other (39, p. 56). This advice was — 
followed in 1904 by Director Saxelund, of the Norwegian forest — 
service, who ordered that no more Pinus strobus should be planted | 


in the Gov ernment nurseries at Sandnes.?! 


DENMARK. 


Rostrup, in Denmark, 1889, issued a bulletin to the forest guards — 
dena with the dangerous tree diseases, in which he advised that — 
Ribes and white pine should always be separated (35, p. 11). The 
only case of the removal of Ribes from the vicinity of a white-pine 
plantation in Europe was brought to the writer’s attention at Cor- — 
selitz, Denmark. The plantation referred to was located near the ~ 
cottage of a forest guard, and 20 years ago an order was issued that — 
no Ribes should be grown in the cottage garden. On what authority 
the order was issued is not known, but it is believed to have come 


from Rostrup. The removal of the black currants effectively 


checked the spread of the rust, and to-day the trees are thrifty. In : 
contrast to this, consider the appearance of the 34-year-old white- F 


pine plantation suffering from severe crown infection shown in 


a 


1 Oral information from Skogforvalter A. Jenssen, Stavanger, Norway. 


idl 


WHITE-PINE BLISTER RUST IN WESTERN EUROPE. 19 


Figure 9. No control measures were attempted here, the result being 
that 90 per cent of the trees are diseased. 


FRANCE. 


French foresters to date have given the fungus little attention, 
for white pine is of secondary importance to them, and they have 
been concerned with forest problems of a nature more vital to their 
country. The writer found no case where the uprooting of Ribes had 
been attempted or sil- 
vicultural methods 
undertaken to control 
the disease in France. 
The blister rust is 
nevertheless working 
destructively in their 
plantations. Figure 
10 shows a 17-year-old 
stand wherein 52 per 
cent of the trees are 
attacked so seriously 
that it is doubtful 
whether they will ever 
reach maturity. 


BELGIUM. 


Notable among re- 
cent Belgian investi- 
gators dealing with 
the blister-rust fungus 
are Professor Mar- 
chal; Professor Bom- 
mer, of Brussels; For- 
est Inspector Pechon; 
and Professor Quai- 
riere, of the research 
station at Groenen- 
dael. With the excep- 


tion of ae experl- Fue. fom 34-year-old white pine plantation at Almindin- 
gen, island o ornholm, Denmark, in which 90 per 

rite nts made with cent of the trees have been attacked in the crown by the 
fungicidal treatment white pine pester Aue eeany, af ane co killed by the 
. rust have been felled. Some of the diseased trees had 

at the experiment sta- their weakened tops broken off by the wind. 


tion at Groenendael, 
the writer saw no cases where the suggested control methods have 
been adopted. Bommer emphasized the need of exterminating 
the fungus in the nurseries by destroying infected trees. Pechon 
in conversation with the writer placed little faith in the treatment 
with chemical solutions to check the development of the fungus and 
strongly advised the removal and burning of infected trees. Such a 
practice, however, is futile unless the currants and gooseberries in 
the locality are also destroyed. 

It is a common practice in many European nurseries to grow white- 
pine stock and Ribes near each other. After attention was called to 


20 BULLETIN 1186, U. S. DEPARTMENT OF AGRICULTURE. 


the blister-rust menace several of the nurseries of Belgium and 
France specializing in conifers for exportation discontinued the 
growing of black currants, since this species caused the most damage 
to pine. In other nurseries where the currants are of major im- 
portance the cultivation of five-leaved pines has been abandoned. 
The nursery beds shown in Figure 11 are in one of the largest of the 
French forest nurseries, situated near Orleans. These were started 
since the war and contain Austrian and Scotch pines, but no Ameri- 
can five-needle pines, the growing of which was discontinued. 


BRITISH ISLES. 


British foresters declare the rust to be altogether too prevalent, 
but have made no efforts to control it. The fungus has raised more 
interest and concern among fruit growers than it has among the 
foresters, because the former feared a decrease in their black-cur- 
rant crop, entailing financial loss. . 


Fic. 10.—A 17-year-old white-pine plantation near Epinal in the French Vosges. 
Blister rust has attacked 52 per cent of the trees. This entire plantation is ex- 
posed to further infection from black-currant bushes growing 600 feet distant. It 
is doubtful whether merchantable timber will ever be obtained from it. 


Trials made at Oxford, England, to check the rust by spraying — 
Ribes proved quite unsuccessful (2, p. 24). Reference to the spray- 
ing of young pines with a fungicide is made in the Quarterly Jour- 
nal of Forestry (4), with a statement that in a Belgian nursery seed- 
lings sprayed with a 1 per cent solution of potassium permanganate 
had been effectively protected. Chemically treating diseased parts of 
stem or limb may retard the development of the disease, but results 
thus far obtained are rather uncertain. Silvicultural methods will 
never control the fungus as long as Ribes bushes are permitted to 
grow in the neighborhood, but the opinion prevails that such methods 
may slightly decrease the amount of infection through better aera- 
tion and the entrance of more sunlight into the stand, especially if 
it occupies a moist site. If the black currants had been removed 
from the neighborhood of the plantation at Oxford, it would not 
be in its present poor condition (fig. 12). 

Control of a forest disease on as extensive a basis as the blister- 
rust work in the United States has no parallel in foreign forest prac- 
tice and presents a striking contrast to the limited measures of con- 


WHITE-PINE BLISTER RUST IN WESTERN EUROPE. ae 


trol which they have applied to small groups or isolated.ornamental 
specimens. Strenuous efforts to control the blister rust wherever it 
occurs are not made in Europe because the tree lacks the commercial 
status necessary to warrant such action. 

No European country has carried out a definite scheme of study 
for the control of Cronartium ribicola covering a number of years. 
The work done in the past has been conducted by individual initia- 
tive and interest, the investigators working independently and in 
some cases apparently unaware of each other’s activities. The work 
in Sweden by Eriksson was prompted by a popular fear lest the 
disease on Pinus strobus should prove a menace to the native Pinus 
sylvestris, the principal forest timber species. 


GERMANY. 


Klebahn’s work in Germany was undertaken from a purely sci- 
entific viewpoint. He paid little attention to the practical side of the 
question when he saw 
that the foresters were 
not concerned about 
it. When the United 
States restricted the 
entry of five-needle 
pine nursery stock in 
1912 because of the 
fungus, the nursery- 
men took a greater in- 
terest in the subject. 
Large nurseries situ- 
ated near Halsten- 
beck, Germany, con- 
ducting an extensive 
export trade were par- 
this restriction, ‘They ss antSense caste cota Sunes bine, oth 
called upon Klebahn 
_ to witness that their stock was free from blister rust, which testimony 
he was bound to decline, since the fungus is difficult to detect on seed- 
lings. To Klebahn’s knowledge measures against the disease have 
not been taken anywhere in Germany, since Pinus strobus, aside 
from the nurserymen’s point of view, is of small economic im- 
portance. It is said that in the municipal forest of Heidelberg there 
are mature white-pine plantations covering nearly 150 acres. This 
is probably the largest single plantation of the species in Europe. 
Professor von Tubeuf, who has made a careful study of the blister 
rust in Germany, expects that in the future white pine will be grown 
less and less in that country.” 


SIGNIFICANCE OF EUROPEAN EXPERIENCE TO AMERICA. 


The observations made abroad on the susceptibility of sugar pine, 
western white pine, and the limber pine show that these species are 
as readily attacked and as severely damaged by the white-pine blister 
rust as is the eastern white pine. Laurie found western white pine 


” Correspondence with Professor von Tubeuf, 1920, 


22 BULLETIN 1186, U. S. DEPARTMENT OF AGRICULTURE. 


fatally attacked at Murthly Castle, Scotland, in 1893, although no 
record of the occurrence was published until 1898 (26). The rust 
so badly damaged and disfigured the beautiful ornamental specimens 


v Dose 
. hte 
o> each 


ec. ‘ 
ys = 3 


: A oes gees 
Ngee le A ce A pe 
. _ vat 
Eo Ttod . i - 
Ge shh 


ea 

Poe 
z Se oe » 
Cee %, 
5 Bis 
4 a 

< 
; 


Bs 


a) ise Ste ive: 


Fic. 12.—Interior view of a white-pine plantation in Bagley Wood, near Oxford, Eng- 
land, in which 84 per cent of the trees are in a dead or dying condition. Every tree 


shown is diseased, and the tree in the foreground produced spores on October 15, 
1920. Black currants were growing only 100 feet away. 


growing in the Murthly Castle Park, which had reached a height of 
60 feet, that it was necessary to cut them down. To-day, only one 
tree remains of the original group of 50. This tree, having a 
diameter of 26 inches and a height of nearly 90 feet, is probably the 


WHITE-PINE BLISTER RUST IN WESTERN EUROPE. OS 


largest specimen of western white pine in the British Isles. It, too, 
is being killed by blister rust. In young plantations of western 
white pine at Balmoral Castle, Scotland, the blister rust is gradu- 
_ ally working with telling effect. Neger reports this species as being 
attacked by the rust in Germany (30, p. 280). 
The California sugar pine was found diseased in Scotland, France, 
and Belgium, and is reported from Germany.’* A most striking 
example of damage done to a single tree was observed at Murthly, 
Scotland. An arboretum specimen, 20 years old, with a height of 
20 feet, is so heavily attacked on every limb to a height of 8 feet 
from the ground and so severely constricted on the stem that it is 
_ practically worthless. The late Sir Edmund Loder, of Horsham, 
Sussex, England, stated in correspondence that young sugar pines 
on his estate were attacked and killed by the rust. The appearance 
of infected trees in Belgium and France indicates that this species 
is highly susceptible. 
_ The limber pine was seen diseased in Norway, Sweden, and France, 
and Tubeuf states that it is infected in Germany (42). One of the 
most interesting cases of damage to the limber pine by the blister 
rust was seen at Softeland, near Bergen, Norway. In a plantation 
_ of {-year-old trees numbering 300, each tree was diseased and one- 
third of the number killed. The infection may be directly attributed 
to black-currant bushes growing in a garden 650 feet distant. At 
the Alnarp Forest nursery in Sweden 100 seedlings 6 years old 
were destroyed in 1920 because they were found to be diseased. A 
few younger seedlings remaining in the nursery (fig. 13) had de- 
veloped the disease in only two cases. In the National Arboretum 
at Nogent sur Vernisson, France, 12-year-old trees of this species 
_ have been killed by the disease (fig. 14). 

The Mexican white pine is heavily infected, the disease being 
found on this species in Belgium and England. Extensive planta- 
tions of these trees do not exist abroad, since they have been planted 
chiefly for ornamental purposes. The severity with which the 
fungus has attacked them and its rate of development clearly demon- 
strate that they are readily susceptible. 

These facts are of special significance to the United States and 
sound a clear call to action. ‘The recent discovery of white-pine 
blister rust in British Columbia and Washington and the wide- 
spread abundance of wild currants and gooseberries in the Pacific 
coast and Rocky Mountain regions (there being about 60 species) 
place the valuable western five-needle pines in an extremely hazard- 
ous position. Furthermore, climatic conditions of the West appear 
to be favorable to the spread and development of the fungus. 
There is a striking resemblance between the climate of western Nor- 
way, where the disease worked destructively in white pine and limber 
pine, and the northwest coast of the United States. Observations 
in Norway on the growth of the Douglas fir and Sitka spruce show 
that these indigenous species grow admirably in that region, thus 
giving evidence of the similarity of the climate of the west coast 
of Norway and of America. -They give such promise of excellent 
volume production that in the future these trees will undoubtedly 
play an important role in the forestry practice of that country. 


8 Correspondence with Professor von Tubeuf, 1920, 


24 BULLETIN 1186, U. S. DEPARTMENT OF AGRICULTURE. 


During the wet summer of 1917 (2, p. 24) the blister rust de- 
veloped so heavily and so seriously on cultivated black currants in 
England that nurserymen became alarmed and feared a decided 
setback to their currant crop because of defoliation of the bushes.“ 
A climatic cendition favorable to the spread of the rust on the 
currants results in an increased amount of pine infection. French 


Fie. 138.—Limber pine (Pinus flexilis) growing in a nursery at Alnarp, Sweden. Blister 
rust first appeared here in 192U, at which time 100 seedlings 6 years old were de- 
stroyed. The young trees were growing within 300 feet of black currants and goose- 
berries. This shows the results that may be expected from an exposure of this species 
to the white-pine blister rust, 


foresters maintain that the disease is much more abundant during 
a wet year than in a dry one.® A similar opinion is upheld by 
members of the Belgian forest service. In the western United 
States the two factors of an abundance of wild currants and goose- 
berries and a climatic condition favorable to the fungus will work 
together to the detriment of the five-needle pines. European cli- 


e 14 Notes obtained from Kew Garden Laboratory, through the courtesy of Dr, A, D. 
otton. ; : 
16 Oral statement to the writer, 


oy 


<a 
\ 


Degas! 


#7 


and gooseberry bushes 


_white-pineforests. 


-eent careful studies 


WHITE-PINE BLISTER RUST IN WESTERN EUROPE. "95 


matic conditions suitable to the growth of the five-needle pines were 
found favorable to the development of the blister rust. 


ECONOMIC ASPECTS OF THE BLISTER-RUST PROBLEM. 


The problem of controlling the blister rust in eastern North 
America is distinctly an economic one, and the practical application 


of forest pathology must aid in the protection of a basic industry 


by maintaining forest production. The task at present has developed 
beyond protecting merely a restricted area; 1t involves the entire 
country west as well as east. It has been positively demonstrated in 


eastern North Amer- 


ica that this disease 
ean be controlled at a 
reasonable cost by up- 
rooting alleurrant 


within 900 feet of 


The blister rust can. 
not be eradicated 
from North Amercia, 

but the local destruc- 

tion of currants and 

gooseberries prevents 

damage to pines 

within the control 

area. 

The value of the 
commercial eastern 
white pine alone 
amounts to $276,- 
000,000 7 an asset 
well worth insuring 
against the rust. Re- 


made on the rate Fig. 14.—Limber pine (Pinus flexvilis) in the National 


O h Arboretum at Nogent sur Vernisson, France, dying from 
f s P © 2 d of the a blister-rust attack. The 12-year-old tree in the center 
fungus in New York, ee Sage ty ai ae na ite i pate igi! “ne ste 

x owing and shedding o e needles, an ied the fol- 
New Hampshire, Ver lowing year. This species appears to be a ready victim 
mont, and Massachu- to the rust. 


setts show 15 per cent 

general infection. This is only the beginning of the invasion, for 
the disease is comparatively young here, having been only 25 years 
in the country and not imported to any appreciable extent until 
1909. During the next decade it will gain impetus, spread with ever- 
increasing force, and impress its seriousness upon the public mind. 
The crux of the situation lies.in the fact that the young white- 
pine growth which should become the commercial stands of the 
next 30 years will be severely hit. Clearly the control of the disease 
by the removal of currants and gooseberries in the East must. be 
vigorously pursued. 


16 Hstimate of the United States Forest Service. 


26 BULLETIN 1186, U. S. DEPARTMENT OF AGRICULTURE, 


WESTERN NORTH AMERICA. 


One of the grave problems now confronting the Federal and State ~ 
Governments is the safeguarding of the five-leaved pines of the 
West from this European pest. Now that the disease has made its 
appearance in British Columbia and Washington, what will be the ~ 
result? The final outcome is difficult to forecast, but it is certain 
that the western five-leaved pine forests are in grave danger. Ob- 
servations made in Europe upon the susceptibility of sugar pine, 


western white pine, and limber pine to the fungus showed that | 


these trees are as readily attacked and as severely damaged by 
the white-pine blister rust as is the eastern white pine. It means 


that $228,400,000** worth of growing timber is to become the prey ~ 


to a very insidious and dangerous disease. A widespread attack — 


in this region is imminent and threatens to bring immeasur- | 


able loss to private owners as well as to the Federal Government. 
To judge from the severity of the disease on these species of pines 
in Europe, it is no exaggeration to predict that the presence of the — 
blister rust in the Northwest threatens the future position of these 
valuable pine species in the timber markets of the world. : 


DECIDED STEPS OF ACTION NECESSARY. 


The action demanded by present conditions in order to control the 
blister rust is summarized as follows: 

(1) Energetic control of the disease in the East by the general 
eradication of currants and gooseberries in pine-growing sections. 

(2) Prompt and decisive action to control the disease in the West. 

(3) Eradication of the cultivated black currant, the most suscepti- 
ble alternate host of the blister rust and the most active agent in its 
spread and establishment. 

(4) Strict adherence to and prosecution of the quarantine laws 
prohibiting the shipment of five-needle pines and currant and goose- 


berry plants from infected territory. Also the continued enforce- 
ment of the quarantine placing an absolute embargo on foreign — 


nursery stock, thus preventing the entrance of the blister rust and 
other pests from foreign countries. Conditions demand such action. 


The scope of the problem is more than regional or national; itis _ 


international. Neither evasion of the quarantines nor laxity in the © 
prosecution thereof can be permitted. The liability is large and the 
hazard great. 


SUMMARY OF THE BLISTER-RUST SITUATION IN EUROPE. 


The white-pine blister rust was first discovered some 65 years ago 
on pine and currants in the Baltic Provinces of Russia. Six years 
later it was seen to attack seriously 30-year-old white-pine trees in 
Finland and was marked as a dangerous tree disease. It is difficult — 
to state where the disease originated, but the facts available to the 
writer indicate that Russia was the original home and Pinus cembra 
its host. From there it migrated and gradually spread over western — 
Europe. f 

Its occurrence was noted with increasing frequency from 1880 to — 
1900, particularly in those countries, such as the British Isles, Den- — 
mark, Germany, and Sweden, in which plant pathology is carefully — 


17 Hstimate of the United States Forest Service. 


WHITE-PINE BLISTER RUST IN WESTERN EUROPE. 27 


~ studied and in which tree species from America were being con- 
tinually sought for experimental forest planting and ornamental 
purposes. 

The first known occurrence of white pine in Europe was in the 
~ Royal Nurseries at Fontainebleau, France, in 1553. It was not exten- 
sively planted until after its first introduction into England in 1705 
and later into other European countries. From the outset it gained 
the high regard of arboriculturists and foresters abroad because 
of its distinct ornamental beauty and the excellence and suitability 
of its wood for many purposes. To-day it is well known in Europe, 
having been one of the most widely distributed of the introduced 
American trees. ; 

Nurseries undertook the cultivation of white-pine stock for do- 
_mestic sale and for export trade in localities where currant and 
gooseberry bushes were present, a practice which contributed largely 
_ to the spread of the fungus in Europe and America. As the de- 
mand for nursery stock increased, European nurseries, particularly 
those of Germany and France, undertook to meet the requirements. 
- Until 1912 they could raise and ship white pines to America with- 
out restriction. This policy resulted in the importation of the white- 
pine blister rust into America about 1898, and this plague gradually 
spread through the northeastern white-pine region. Later, probably 
about 1910, it was introduced into British Columbia and has recently 
reached Washington. 

The spread of the blister rust followed the increase in the distri- 
bution of white pine in European countries, reaching even to the 
northernmost plantings of the species in Norway. Eastern white 
pine is not the only member of the American five-leaved pine group 
attacked by the blister rust. Other five-leaved pine species intro- 
duced into Europe for ornamental and experimental planting have 
likewise become affected. Prominent among these are the California 
sugar pine, the western white pine, the limber pine, and the Mexican 
white pine. These species appear to be as readily susceptible as the 
eastern white pine. 

Cultivated black currants and gooseberries, especially black cur- 
rants, are very plentiful in European countries, and through them 
the disease is perpetuated with ever-increasing volume. Wild cur- 
rants and gooseberries are very limited as to the number of species, 
and the bushes are scarce in the forests. The control of blister rust 
as a forest-tree disease does not appear to have been seriously at- 
tempted abroad. A few efforts have been made to check the fungus 
on individual ornamental trees by removing the infected parts or 
treating them with chemical solutions. The wholesale removal of 
cultivated and wild currants and gooseberries is not practiced, not 
because of lack of knowledge of the damage done by the diseased 
currants, but because the currants are of more value to the people 
than the foreign white pine. 

The blister rust is gradually driving the white pine out of Europe. 
Unfortunately, the stands are gradually disappearing in Europe be- 
cause of damage by the blister rust. Foresters generally are express- 
ing the opinion that the damage done by the fungus is too large to 


_ permit raising the species at a profit. Often over 90 per cent of the 


trees in plantations are infected, and frequently one-third have been 
killed by the blister rust. Mature trees also are fatally attacked. as 


28 BULLETIN 1186, U. S. DEPARTMENT OF AGRICULTURE. 


shown on eastern white pine in Sweden and France and western white 
pinein Scotland. Many European foresters have been enthusiastic over 
the future prospects of white pine in their countries, believing that it 
would come to occupy an important position in theirsystem of manage- 
ment and be regarded as an indigenous species. As shown by its growth 
abroad ‘it has excellent volume ‘production, regenerates well (fig. 15), 
and is not exacting as to soil and moisture requirements. Such an 
optimistic outlook was held by foresters in Denmark, Belgium, and 
Norway, while the Germans had faith enough in the productive 
capacity of the species to plant considerable areas with white pine. 


eae 


IRE TS 


en a 
Boe 
at. 
ave 


Fic. 15.—Natural white-pine reproduction in the communal forest of La Mouche, Kpinal, 
France. In this part of the forest 36 per cent of the young trees were attacked by 
the blister rust, thus greatly reducing the probability of a future crop. 


Other foreign conifers, such as Douglas fir, Sitka spruce, and 
Japanese larch, will gradually replace the disappearing white pine. 
Himalayan and Balkan pine will also come into more extensive use 
for forest planting. 


EUROPEAN EXPERIENCE A WARNING TO AMERICA. 


This disease is a most dangerous forest enemy. It readily kills 
mature trees, but the greatest menace is in sweeping out of existence 
the young pine stock of to-day which is to become the mature timber 
of to-morrow. Although it is slow in developing, it is nevertheless 
constant in action and certain in destruction, undermining the very 
security of our forest capital, without which continued forest pro- 
duction is impossible. 

Blister-rust control is a national problem. It is necessary to pro- 
tect a resource so essential as white pine for economic and industrial 
development. Simple and practical methods are available to any 
pine owner in the eastern United States which enable him to safe- 
guard his pines from this disease. The blister rust is spreading into 
the western white- -pine and sugar-pine forests and threatens the com- 


mercial extinction of these species. Vigorous action is required to de- - 


velop and apply measures that will minimize the damage in the West. 


- 
» 
- 
= 

< 


, ee ee ee ne ee ae 


(1) 


(2) 
(3) 
(4) 
(5) 


(6) 


(7) 
(8) 


(9) 


(10) 
(11) 
(12) 
(13) 
(14) 


(15) 


(16) 


LITERATURE CITED. 


ANONYMOUS. 

1765. An account of the premiums offered this year (1765) by the 
Society for the encouragement of arts, manufactures, and com- 
merece. For planting and husbandry. In Museum Rusticum et 
Commerciale, v. 4, p. 379-890. 


1920. Report on the occurrence of insect and fungus pests on plants 
in England and Wales in the year 1918. Bd. Agr. & Fisheries 
[Gt.. Brit.], Misc. Pub. 23, 69. p. 


AYRES, THOMAS. 
1824. A description of a remarkably large gooseberry plant. In 
Trans. Hort. Soc. London, v. 5, p. 490-491. 


BALTz. = A 
1919. Die Weymouthskiefer (Pinus strobus). Jn Forstw. Centbl., 
Jahrg. 63 (N. F. 41), p. 302-307. 


Beevor, Hucu R. 
1919. Young woods in Belgium. Jn Quart. Jour. Forestry, v. 138, p. 
272-275. 


BELGIUM. CONSEIL SUPERIEUR DES FORETS. 
1909. Rapport sur l’introduction des essences exotiques en Belgique, 
par le Comte Amédée Visart et Charles Bommer. 881 p., 6 pl. 
Bruxelles. Liste des ouvrages cités, p. 361-365. 


BuiyTtT, AXEL. 
1896. Bidrag til kundskaben om Norges soparter. Forhandl. Vidensk. 
Selsk. Christiana, 1896, No. 6, 75 p. 


BOLLE, CARL. 


1890. Wann erscheint die Weymouthskiefer zuerst in Europa? Jn 
Gartenflora, Jahrg, 39, p. 484-438. 


COVILLE, FREDERICK VERNON, and BRITTON, NATHANIEL LorpD. 
1908. Grossulariaceae. Jn North Amer. Flora, v. 22, p. 193-225. 


DETWILER, SAMUEL B. 
[1921.] White pine blister uae control, 1920. Jn Bul. 6, Amer. Plant 
Pest Committee, p. 1-6. 


DIETRICH, HEINRICH AUGUST. 
1859. Blicke in die aap iacmenecle der Ostseeprovinzen. Jn Arch. 
Naturk. Liv- Ehst- und Kurlands, Ser. 2, Bd. 1, p. 261-416. 


Etwes, Henry JoHNn, and Henry, AUGUSTINE. 
1910. The trees of Great Britain & Ireland, v. 5, p. 1001-13338, pl. 
271-339. Edinburgh. 


ERIKSSON, JAKOB. 
1890. Landtbruksbotanisk berittelse. 17 Blasrost 4 tall (Peridermium 
Pini (Willd.) Wallr. och P. Strobi Kleb.) Jn Landtbr. Akad. 
[Sweden], Handl, och Tidskr., Arg. 29, p. 223-225. 


1896. Nagra iakttagelser rérande blasrosten 4 tallstammar, dess 
natur och forekomstatt. Jn K. Landtbr. Akad. [Sweden]. Handl. 
och Tidskr. Arg. 35, p. 240-258, 3 fig. Bibliographical footnotes. 


FIscHER, EDUARD. 
1898. Beitrage zur Kenntniss der schweizerischen Rostpilze. Jn Bul. 
Herb. Boissier, t. 6, p. 11-17. 


GOBLET d’ALVIELLA, FELIX. 
1919. Eléments de sylviculture, v. 1, xiv, 383 p., SC ie. Parts, 
Bruxelles, Principaux ouvrages consultés, p. 371-3872. 


29 


30 BULLETIN 1186, U. S. DEPARTMENT OF AGRICULTURE. 


(17) Hanson, C. O. / er 
1911. Forestry for woodmen. 222 p., 15 fig., 12 pl. Oxford. 
(18) Histncrer, Epwarp. 


1876. Peridermium pini (Willd.) Pers. a perch dita Pin as” 
strobus. Jn Bot. Notiser, 1876, p. 75. att 


(19) Hooxerr, J. D. 
1879. The flora of British India, v. 2, 792 p. London. 


(20) Howarp, ALEXANDER LL. “4 
1920. A manual of the timbers of the world... xvi, 445 p., illus. 

London. a 

(21) JaANCZEWSKI, EDUARD, RITTER VON GLINKA. a 
1907. Monographie des a Ribes L. In Mém. Soc. Phys. 

et Hist. Nat. Genéve, t. 35, p. 199-517, illus. ; 


(22) KiEeBpaHn, H. FF 
1888. Uber den Rindenrost der Weymouthskiefer, Peridermium | 
(Aecidium) Strobi. Jn Bot. Notiser, 1888, p. 229-230, 236. 


(23) 1889. Beobachtungen und Streitfragen tiber die Blasenroste. Jn 
Abhandl. Naturw. Ver. Bremen, Bd. 10, p. 145-155, pl. 1. Bibli- 
ographical footnotes. 


(24) Lamarck, J. B. pE, and CANDOLLE, A. P. DE. 
1815. Flore francaise re . Ed. 3, t. 4., 944 p. Paris. 


(25) LastetT, THOMAS. ie 
1894. Timber and timber trees native and foreign. Ed. 2, com- 

pletely revised ...by H. Marshall Ward. xx, 442 p., 34 fig. 

London and New York. 


(26) Lauriz, JAMES. 
1898. Diseased Pinus monticola. Jn Gard. Chron., ser. 3, v. ma p. 244. 


(27) Linn, JENS. 
1913. Danish fungi as represented in the herbarium of E. Hostrap: | 
648 p., 42 fig., 9 pl. List of literature, p. 555-606. 


(28) Lipo, J. Ivar. ' Mi tie 
1908. Uredineae Fennicae, Findlands rostsvampar. Bidr. Kann. Fin- — 

lands Natur och Folk, Hiftet 65, 642 p., 15 fig. babii 332 ofver | 

den i arbetet citerade literaturen, p. 585- 605. : 


(29) Macnus, PAUL. j 
1873. Mycologische Bemerkungen. In Hedwigia, Bd. 12, p. 49-53. 


(30) NeEcrErR, F. W. 
1906. Kleinere mycologische Beobachtungen. In Ann. Mycol., Jahrg. 
4, p. 279-287. 

(81) [N1gPELS, PAvt.] . 
1900. La Peridermium du Weymouth. Jn Bul. Soc. Cent. orcas, Belg., — 
v. 7, p. 577-579. 


(82) OvuprMans, C. A. J. A. 
1885. Aanwinsten voor de flora mycologica van Nederland. IX en X. 
In Nederland. Fianna s = Archief, ser. 2, deel 4, p. 208-278, 

' pl. 46. 
(33) PLowrienHtT, C. B. 
1892. Cronartium ribicola. In Gard, Chron., ser. 3, v. 12, p. ad 501. 


(84) PorRAULT, GEORGES. 
1890. Les Urédinées et leur plantes nourriciéres. In Jour. Bot. 
[Paris], t. 4, p. 229-234, 245-251, 307-315, eee 1% 


(35) Rostrup, EMIt. :. 
1889. Afbildning og Beskrivelse af de farligste Snyltesvampe i Dan- 
marks Skove. 30 p., illus., 8 col. pl. Kgbenhavn. 


(36) 1902. Plantepatologi. ... 640 p., 259 fig. Kgbenhavn, 


d 


WHITE-PINE BLISTER RUST IN WESTERN EUROPE. a 


6 ScHELLENBERG, H. C. 
1904. Der Blasenrost der Arve. Jn Naturw, Ztschr. Land-.u. Forstw., 
Jahrg. 2, p. 283-241, 2 fig. Bibliographical footnotes. 


(38) ScHLicH, WILLIAM. 
: 1919. The Bagley Wood itt plots. Jn Quart. Jour. Forestry, v. 
13, p. 266-268. 


(39) Scu¢yen, W. M. 
1897. Beretning om Skadeinsekter og Pibaiekyeadinhd i 1896. 58 p., 
% illus. (Report of State Entomologist, Norway.) 


peed) SPAULDING, PERLEY. 
1911. The blister rust of white pine. U. S, Dept. Agr., Bur, Plant 
Indus. Bul. 206, 88 D-, 5 fig., 2 pl. Bibliography, p. 61-78. 


(41) TAayLor, MINNIE W. 
; 1922. Pétential sporidia production per unit in Cronartium ribicola. 
In Phytopathology, v. 12, p. 298-300, 1 fig. 


(42) TUBEUF, CARL VON. 

* 1914, Neuere Versuche und Beobachtungen tiber den Blasenrost der 
Weymouthskiefer. Jn Naturw. Ztschr.-Forst- u. Landw., Jahrg. 
12, p. 484-491. 


(48) TULASNE, L. R. 
1854. Second Mémoire sur les Urédinées et les Ustilaginées. Jn Ann. - 
Sci. Nat. Bot., sér. 4, t, 2, p. 77-196, pl. 7-12. 


(44) Wappss, L. 
1896. Zur Naturgeschichte der Weymouthskiefer. Jn Forstl. Naturw. 
Ztschr., Jahrg. 5, p. 205-219, pl. 18-14. French translation, without 
plates, in Bul. Soc. Cent, Forest. Belg., v. 4, p. 105-123. 1897. 


AY, Vigieesgte BLISTER RUST may destroy much of the 

white pine of the United States. This destructive dis- 
ease probably had its original home in Asia, later reaching 
Europe. It was introduced into America during the years 
1898 to 1910. European and American investigations indi- 
cate that this rust can not spread direct from pine to pine 
and that an intermediate stage of development on currant and 
gooseberry bushes is necessary before it can harm the pine. 
Studies of the disease in this country showed that the dis- 
iance to which currant and gooseberry bushes infect pines 
is comparatively short. This knowledge is the basis of the 
local control work in the United States, which was begun 
experimentally in 1916. These experiments prove that un- 
der ordinary forest conditions in the eastern United States 
a stand of white pine is subject to little or no damage 
from the rust if there are no European black currants grow- 
ing within a mile and no other currant or gooseberry bushes 
within 900 feet. European black currants are dangerous to 
pine at greater distances than other species because they are 
more susceptible to the rust and produce a much larger 
volume of spores per unit of infected leaf surface. 

The purpose of the study in western Europe in 1919-20 
was to determine how destructive the blister rust had been 
to American white-pine species planted abroad and what 
steps, if any, had been taken to combat this disease in for- 
eign countries that would be of practical value in control- 
ling the disease in the United States. It was found that 

- cultivated black currants and gooseberries, especially black 
currants, are very abundant in Europe and popularly con- 
sidered of more value than the foreign white pine. Conse- 
quently these bushes have not been removed from the 
vicinity of the white-pine plantations, and the blister rust is 
gradually driving these trees out of Europe by destroying © 
such a large percentage that it is unprofitable to cultivate 
ihe species. White pine is being supplanted by other for- 
eign conifers, such as Japanese larch, Douglas fir, Sitka 
spruce, and Balkan pine. 

Very recently the blister rust has been found on the 
Pacific coast in Washington and British Columbia. This 
discovery is a matter of great concern, since there are 
seven different white-pine species in the West and the coun- 
try’s greatest white-pine resources are centered in the 
western white-pine and sugar-pine forests. Western white 
pine and limber pine apparently are more susceptible to the 
blister rust than eastern white pine. Sugar pine is also 
highly susceptible. To delay the spread of the rust through 
the eradication of cultivated black currants and quarantine 
enforcement and the development of practical local control 
measures adapted to the conditions found in western forests 
are the only alternatives to the ultimate extinction of the 
most valuable commercial pine-timber species of the West. 


82 WASHINGTON : GOVERNMENT PRINTING OFFICE : 1923 


Washington, D. C. v August, 1924 


EFFECT OF KILN DRYING, STEAMING, AND AIR SEASONING ON CERTAIN 
FUNGI IN WOOD.’ 


By Ernest E. Husert, Assistant Pathologist, Office of Investigations in Forest 
Pathology, Bureau of Plant Industry. - 


[In Cooperation with the Forest Products Laboratory of the Forest Service. ] 


CONTENTS. 

Page Page 
Derenneet eee 1 | Brief summary of the test runs____ 10 
peeviene WOTk .___....-___. Jig} b2— 2 | Air-seasoning experiments -________ 14 

.Material used in this study___--_-- 3 | Revival of fungi in wood after air 
Mecwias OF seagyut 5 kale tt a ee aes Ha Se he ae 15 
Cultural methods. — 222 .224+-.+4 5 | Review of the results’'__-___._-~___- 17 
_Kiln-drying and steaming experi- SUMUPATY, ate Se be eet 19 
| Te Se) GRE OS ee ROR eS 6 T thteretese Cited ~-— =. L»__... 20 

INTRODUCTION. 


Among lumbermen and kiln-drying experts the belief is general 
that the temperatures and humidities used in the various commercial 
kiln runs and steaming processes, with the exception of stock that 
requires low temperatures and high humidities, are efficient in killing 
the various stain and decay producing fungi found in lumber and 
other wood products. Accurate tests to support this belief have 
never been made. It was the object of this study to determine 
whether the fungi in lumber are killed under ordinary commercial 
kiln conditions and steaming processes and to gain some idea of the 
minimum time and temperature limits necessary to kill these organ- 
isms. Such information has a wide application in the steaming 
processes commonly applied to gum, poplar, and other hardwoods 
previous to air seasoning and to the steaming of billets in the cooper- 
age and other industries. It also has a very important bearing 
upon the sterilization of ties, posts, and poles and of mine, bridge, 
and building timbers when treated by a preservative process where 


1This manuscript was submitted for publication December 24, 1923. , 

- Acknowledgments are due to Miss A. M. Waterman for aid in culturing some of the test 
blocks; to members of the section of timber physics, Forest Products Laboratory, for aid 
and advice in handling the dry kilns; and to Dr. C. J. Humphrey for advice in outlining 
the project and furnishing samples of infected wood. 


91940°—24——-_1 


) BULLETIN 1262, U. 8. DEPARTMENT OF AGRICULTURE. 


heat is introduced as a preliminary steaming or during impregn: 
or both. ut. 3 HAT 


In most of the kiln-drying and steaming processes now in use where 
sufficiently high temperatures are used it serves the double purpose 
of seasoning and sterilizing the wood. However, in many of the 
steaming processes used primarily for the purpose of softening the | 
wood little or rio attention is paid to the sterilization of the stock. 
Adjustments in temperatures and periods of heating may not on y 
result in the killing of such fungi present in the wood before treat- | 
ment but may prove beneficial in rapidly drying the surface of the 
wood during subsequent air seasoning and thus aid in the prevention | 
of sap stains, molds, and decay. The slack cooperage industry | 
presents among others one notable case for experimentation along 
these lines. | 
In the preservative treatment of wood where heat is used during 
the process the sterilization of the inner portions of the wood not 
penetrated by the preservative is often desirable. Very often ties, 
posts, poles, and timbers of various kinds contain before treatment 
certain active decay organisms which are fully capable of reviving 
under favorable conditions, continuing the decay process, and even- 
tually weakening the wood. Sterilization would not only greatl 
reduce the chances of loss from such a source, but would make it 
possible to utilize for less exacting purposes material containing to 
a limited extent certain types of incipient decay. 4 
In this connection it is necessary to take into account. several fac- 
tors, among which the efficiency of the preservative, the relative ab- 
sorptivity, and the strength qualities of the infected wood are 
paramount. | & 
In the control of blue stain in lumber the use of chemical dips can 
at best protect only the surfaces of the wood against the stai af 
organisms. In case the fungus is already present in the log before 
it 1s sawed into boards the dip solution has no effect upon the fungus 
within the board. Heat treatment in conjunction with the chemical 
action therefore would greatly increase the protection against blue | 
stain. Lis 
Steaming is the common method of applying heat in most of the | 
commercial operations connected with the production and manu- | 
facture of wood, although electricity may be used effectively in some 
cases. Directing an electric current through wood has been tested 
in this country, in France, and in Australia as a rapid method of 
seasoning,” and it is conceivable that the electric current may be used 
to advantage in the sterilization of wood, particularly as a means 
of checking incipient decay of structural timbers in buildings, ships, 
bridges, or other structural units where it may be found impracticable 
to apply other means of heating. > bits 


PREVIOUS WORK. = 


Both Hoxie (2)* and Snell (8, 9) have contributed to the subject 
of the effect of heat on fungi in wood. Hoxie tried the experi- 


ve 
Y 
*. 


| 
| 
| 


*s 
ot 
“* 
, 
z.. 
‘ig 


?Menzel, C. A. Preliminary experiment in the drying of wood by passi an. electr ic 
current through it. U.S. Dept. Agr., Forest Serv., Forest Products Lab. "Sunpublis he 


manuscript. 
*'Th 


1921. 2 
e serial numbers (italic) in parentheses refer to “ Literature cited,” at the end of 
this bulletin, ; : a 


_ 


| 


= EFFECT OF KILN DRYING, ETC., ON FUNGI IN WOOD. 83 


ment of heating a mill, the timbers of which,were infected with dry 
rot, to about 115° F. The heat was applied from Saturday noon 
until Monday morning on four different occasions. Hoxie states that » 
specimens were cultivated from 40 of the badly rotted beams and only 
4 showed living fungi. The fungus in this case was given as Meru- 
lius lachrymans, which is particularly sensitive to heat. Snell, using 
8-inch blocks of spruce artificially inoculated with Lenzites sepiaria, 
Lenzites trabea, Trametes serialis, Lentinus lepideus, and Trametes 
carnea, respectively, subjected these blocks to both moist and dry 
_ heat at varying temperatures and periods of time. The results of 
his tests indicate that moist heat is much more effective in killing the 
fungi than dry heat. None of the fungi within these blocks were 
able to withstand 131° F. for 12 hours at moist heat, while it took 
a heat of 221° F. for 12 hours to kill all the fungi with dry heat. 
The experimental data are limited to tests on 3-inch blocks, but 
statements are made that the temperatures employed in the kiln 
drying of lumber and in the various wood-preservation processes are 
sufficient to kill any fungi within the wood. 


MATERIAL USED IN THIS STUDY. 


' The first lot of material consisted of 18 pulp logs of northern 
white spruce (Picea canadensis)* shipped in from northern Wiscon- 
sin. Six wood-destroying fungi were found infecting this material. 
In some cases the rots of two fungi were present in the same log; as, 
for example, Polyporus anceps in the sapwood and T7’rametes carnea 
in the heartwood, a faint colored zone showing at the junction of the 
two kinds of rot. | : 

_ The second lot consisted of a carload of mixed hardwood and 
conifer logs 16 feet long shipped in from the Menominee Indian 
Mills, Neopit, Wis. These logs were selected by the writer from 
standing green trees on the logging area. An attempt was made to 
find trees with fruiting bodies of the attacking fungus attached, but 
this was not possible in all cases. A total of 23 logs representing 9 
hosts and several wood-destroying fungi comprised the shipment, a 
detailed list of which is given on a succeeding page. The blue-stain 
fungus (Ceratostomella sp.) was found in three of the hosts and 
Torula ligniperda in two hosts. Dark brownish and black discolor- 
ations extending the full length of the log were found bordering the 
incipient decay of the brown cubical rot of tree No. 3 (eastern white 
pine) and trees Nos. 8 and 9 (eastern hemlock). Upon examining 
sections of the dark-colored wood under the microscope, typical spore 
chains of 7’. ligniperda were observed within the wood cells. The 
association of this stain-producing fungus with typical wood- 
destroying fungi in decaying wood is apparently quite general (6). 
_ At the laboratory sawmill, disks 3 inches thick were cut from the 
middle point of each log. These disks were numbered and the decay 


area sketched upon record cards. Photographs taken of some of 
these disks show the types of infection. (PI. I.) 

_ There was some doubt as to the identity of the fungus causing the 
rot in tree No. 18, basswood (T7élta americana). The butt log 
showed a slight hollowing at the base, and within this hollow there 


* Authorities for the scientific names are given in the list on page 4. 


4 ‘BULLETIN 1262, U. S. DEPARTMENT OF | 


dcfvatoned during storage several large rolidereeckemeds 
tentatively determined as a species 0 HE Pholiota. lide a 
the rotted wood was placed in the humidity room and kept r 
In about a month several typical sporophores of Pholiota adipo 
were produced (Pl. II). Typical sporophores have also been pro- 
duced on malt-agar cultures. + akg 
The third lot kof infected logs consisted of a carload shipment of 
Douglas fir (Pseudotsuga taxtfolia) and incense cedar ae $ 
decurrens) shipped by Dr. J. S, Boyce from Oakridge, Oreg. 
Douglas fir logs contained rots caused by Trametes pini, Polypon 
schweinitzit, and Homes laricits. The incense-cedar logs caiiieiae | 
the rot caused by Polyporus amarus. The shipment consisted of 32 — 
logs each 16 feet long, the total scaling 7,790 feet, board measure. | 
A few logs of Alnus oregona, intended for pulping extents 
but rejected when found infected with Polystictus hirsutus and Poly | 
stictus versicolor, were also used in the study, as well as some miscel-— 
Janeous material listed on the following pages. 


List of fungi and hosts. 


Shipment from Port Edwards, Wis.: 
Bawah hirsutus Fr. in northern white spruce (Picea canadensis (i) 
B.S 
Polyporus anceps Pk. in northern white spruce. 
Lenzites sepiaria Fr. in northern white spruce. 
Trametes carnea Nees. in northern white spruce. 
Polystictus abietinus Dicks. in northern white spruce. 
Trametes pini (Thor.) Fr. in northern white spruce. 
Fomes pinicola Swartz in northern white spruce. 
Miscellaneous material: 4 
Polyporus anceps Pk. Murr. in western yellow pine (Pinus ponderosa 
Laws.). a 
Polystictus hirsutus Fr. and P. versicolor Fr. in red alder (Alnus oregon hb |} 
Nutt. ). 
Blue stain in Liquidambar styraciflua L. 
Alternaria sp. in Pinus rigida Mill. 
Trametes pint in Pinus banksiana Lamb. 
Shipment from Neopit, Wis. : 
Trametes pini in larch or tamarack (Larix laricina. (Du Roi) Koch). 
Brown cubical rot in white pine (Pinus strobus L.). . 
Ceratostomella pilifera Fr. and Torula ligniperda, (Willk.) Sacc. in white 
pine. : 
Brown cubical rot in northern white cedar (Thuja occidentalis ae 
Blue stain in northern white cedar. 
Brown ring-rot in northern white cedar. 
Fomes pinicola in hemlock (Tsuga canadensis (l.) Carr.).. 
Torula ligniperda (Willk.) Sacc. in hemlock. pa 
Brown cubical rot in hemlock. 
Ganoderma tsugae Murrill in hemlock. 
Fomes fomentarius Fr. in paper birch (Betula papyrifera Marsh.). 
Fomes igniarius (l.) Gillet in white elm (Ulmus americana L.). 
Trametes pini in white pine. 
Brown cubical rot in northern white cedar. 
Fomes igniarius in red maple (Acer rubrum L.). 
Trametes pini in larch (Larix laricina). 
Pholiota adiposa Fr. in basswood (Tilia americana L.). 
Polyporus borealis in sugar maple (Acer saccharum Marsh.). 
Shipment from Oakridge, Oreg. : 
Trametes pini in Douglas fir (Pseudotsuga taxifolia (Lam.) Britt. tn 
Polyporus amarus Hedg. in incense cedar (Libocedrus decurrens ° 
Polyporus schweinitzti Fr. in Douglas fir. 
Fomes laricis (Jacq.) Murr. in Douglas fir. 


Bul. 1262, U. S. Dept. of Agriculture. PLATE I. 


TRANSVERSE SECTIONS OF HEMLOCK, WHITE PINE, SOFT MAPLE, AND BASS- 
WOOD, SHOWING ROTTED AREAS. 


A, Transverse section of a hemlock ( Tsuga canadensis) log from tree No. 10, showing the incipient 
stage of rot produced by Ganoderma tsugae. .B, Transverse section of a white pine (Pinus 
strobus) log of tree No. 14, showing the ring-rot of Trametes pini. C, Transverse section of a 
soft maple (Acer rubrum) log of tree No. 16, showing the incipient and typical stages of Fomes 
igniarius. The dark area surrounding the central rotted area is the incipient region. D, The 
transverse section of a basswood (Tilia americana) log of tree No. 18, showing the incipient 
rot produced by Pholiota adiposa. Note the darker outer zone of discoloration. 


Bul. 1262, U. S. Dept. of Agriculture. PLATE Il. 


BASSWOOD INFECTED WITH PHOLIOTA ADIPOSA. 


Sporophores of Pholiota adiposa produced on a piece of infected basswood (tree No. 18) which was 
placed in a moist chamber for one month. 


Bul. 1262, U. S. Dept. of Agriculture. erate Ti: 


TIMBER TEST PIECES ILLUSTRATING THE METHODS OF STUDY. 


A, Culture blocks cut from test pieces Nos. 8D and 18D, showing the distribution of the rots 
in the central portions of two4 by 4 inch test pieces. The incipient stage of each rot is seen 
to extend into the center of each. B, Culture blocks cut from the center of 1-inch (lower), 
2-inch, and 4-inch (center and upper) test pieces from tree No. 18. C, Culture blocks showing 
the hollows where fragments have been removed with the chisel forceps. 


ri - 


‘duind oy} Surddo}s pue 3ut}1e}s Ul posn YOUIMs OOTY “YF “AUS oy} 4B WMOYs sdad10J [osTyO OY} YIM PeAourel 018 POOM Pa}oaJUT 


JO syuoMIse1y YOIM UWOIy YOorG einyND “WZ “Pp 
-Uey 94} pues s}USTINAs 
giny[Nd 97} Jo JO110yUI ey} Avids 0 pesn pue dun 


"SLSA.L SHL YOA SAYNLINO ONINVI NI GasM LNAWdINODA GNV ASVD AYNLIND TWldAdS 


OL @ UO SUIPI[S PUB SOfOYULIG YIM UTBIIND YAOTD ‘GT “esBd 9Y} JO episjno ourey ses oy} YALA Seqny 4Se} Jo BUT 
Ul JO UOT}VZI[L10}S 94} SjtULIed YOY osvo Ol} JO Ivel 9} UT suiued9 ‘9 | ‘gq YI0Tq 91N4[Nd ey} Poy 0} pesn duress oyy Jo syed ‘gq ‘esd 
d 18 USALIP AT[BOIIJO9To UB 0} P9yoe}}V WOTJNIOS OTydesTyUe UB IO 10jVM PeT[I}sIP JOY YIM po[[g JoztMoyW Vv 


PLATE IV. 


Bul. 1262, U. S. Dept. of Agriculture. 


Bul. 1262, U. S. Dept. of Agriculture. PLATE V. 


CULTURE TUBES SHOWING NEGATIVE AND POSITIVE RESULTS. 


A, Culture tube showing a negative result; no fungous growth has developed from the fragment 
of wood. The white area on the surface of the agar is due to reflections of light. B, Culture 
tube showing a positive result; the fungus has grown from the fragment of infected wood, and 
a small sporophore (Pholiota adiposa) has developed. 


*% 
F 
a 


“ail EFFECT OF KILN DRYING, ETC., ON FUNGI IN WOOD. 5 


METHODS OF STUDY. 


"The logs and other pieces assembled for this study were cut into 
tes aang at the sawmill of the Forest Products Laboratory under 
the direct supervision of the writer. The 16-foot logs were first cut 
into 8-foot logs. A 3-inch disk was then cut from one of the 8-foot 
ae. (Pl. I.) The 8-foot logs were divided into imaginary 4-foot 
bolts and lettered A, B, C, D, etc., beginning at the first bolt at the 
base of the first lo ‘taken from a tree. The tree number was used 
4 conjunction with these letters in labeling the bolts, the planks, 
and the test pieces cut from each. For example, the first 4-foot bolt 
im tree No. 14 was labeled 14A, the second 14B, and so on, including 
the second and third 16-foot ‘log. The 8-foot logs were cut into 
Q-inch and 4-inch planks, and an attempt was made to include the 
maximum quantity of incipient. decay in each plank. The planks 
from each log were numbered consecutively, and records were thus 
made, showing the position of each plank in the log. Diagrams of 
a longitudinal extent of the rot in each plank were also made. 
; lanks were next cut into the required sizes for test pieces, 1 
by ay ht 24 inches, 2 by 4 by 24 inches, 4 by 4 by 24 inches. These 
are referred to in this bulletin as 1-inch, 2-inch, and 4-inch stock. 
eed test pieces were numbered and sorted. In cutting the test 
pieces care was taken to include in each piece a maximum of the 
incipient stage of decay. Incipient or typical decay extending from 
the edge to the pe of the piece constituted the minimum require- 
ments. (PI. III, A.) 
_ A series of preliminary cultures was next made, using fragments 
of infected wood taken from test pieces cut from each ‘of the logs. 
This was done to test the vitality of the fungous mycelium within 
: the infected wood. 
_ The sets were open piled, using half-inch to 1-inch crossing sticks 
between layers, thus providing free circulation of air about the 
pieces and about the piles. 


CULTURAL METHODS. 


: Upon the removal of the test pieces from the kiln, culture blocks 
2 inches thick were cut from the center of each piece. (Pl. III, 
B.) These were given the piece number and placed in boxes to 
await culturing. The culture work called for special equipment in 
order to handle more efficiently and speedily the large number of 
_ cultures. A special culture or transfer case (Pl. IV) was constructed 
with motor-driven spray apparatus (Pl. IV, A, /), special clamp 
for holding the culture blocks (Pl. IV, 2), an opening in the rear 
of the case allowing the instruments used to be sterilized over a gas 
‘fl me placed on the outside of the case near the opening (Pl. IV, C), 
and a sliding cloth curtain (Pl. IV, D), which allowed the free use 
of the hands during the operations. 
_ The cultural process in detail is as follows: 
A culture block is selected and quickly dipped in a solution of 1 to 1,000 
mei reuric chlorid; it is then split open along a central line with a sterilized 
A het blade. After the interior of the case has been thoroughly sprayed 
distilled water or an antiseptic solution, half of the block is clamped 


as | hown in Plate IV, H. The chisel forceps is next sterilized by dipping 
in 95 per cent alcohol and flaming over the gas jet. The fragments of 


pm) 


ee 
j 


6 BULLETIN 1262, U. S, DEPARTMENT OF AGRICULTURE. 


— 


infected> wood are then cut and pried out of the block with this instrum 
and placed in sterile test tubes containing plain malt agar. The area fr 
which each fragment is removed is numbered and the test tube containi 
it is similarly marked. The block when removed from the clamp shows # 
numbered hollows (Pl. III, C) and their distribution over the face of the 
block. A sketch was made of the split block, showing the areas from vi 
fragments were removed, indicating the stages of decay and the limits i the 
discolored areas. 

A large percentage of the cultures are contamination free, and an averag 
of 96 to 100 tube cultures can be made in two hours. When three out of ge 
tubes showed contamination, or when results seemed doubtful, the cultures 
were repeated. i 

Plain malt, agar° was used in the tubes and the castor of the agar. dianted: 
All cultures were grown at room temperatures and were kept for a minimum 
period of six weeks, in order to observe the negative cultures and watch for 
delayed revival of the fungi in the inoculum. A negative culture is shown in 
Plate V, A, and a positive culture in Plate V, B. ; ity-& 


KILN-DRYING AND STEAMING EXPERIMENTS. 


RUN 1. 


A set of test pieces of the Neopit and Oakridge material was placed 
in a small experimental dry kiln for a period of 16 days. — 

The temperature range during the run was from 120° to 135° F. 
The relative humidity averaged 85 per cent during the test, with a 
range between 100 and 70 per cent. 

Cultures made from the blocks removed from the test pieces at the 
end of the run showed all the fungi to be dead within the Peatets@ 
of all the 1-inch, 2-inch, and 4-inch pieces. 


RUN 2. } 
a i 
Eighteen spruce (Picea canadensis) pulp logs received siren 
northern Wisconsin were sawed into test planks 2 by 10 by 48 inches. 
These logs were infected in the storage pile by various wood- destroy- 
ing fungi, and in most cases both the typical stage and the incipient — 
stage of decay were included in the test planks. Im many eases the — 
rots of more than one fungus were present in the same test plank. 
A set of 20 planks was placed in a Tiemann dry kiln along with a 
commercial run of 23-inch bald cypress lumber for a period of 40 
days. Three planks ‘of western yellow pine (Pinus ponderosa) in-— 
fected with Polyporus anceps and 15 pieces from the Neopit material — 
were also added. The initial temperature was 95° and the end tem-— 
perature 160° F. During the kiln drying the relative humidity — 
ranged between 50 and 84 per cent. At the end of the run, culture — 
cla were cut from the center of each plank. Cultures were made — 
in the usual manner, and it was found that all the fungi had boom 
killed. | 


RUN 3. : 


A set of test pieces of the Neopit and Oakridge rates idinbsed 
was placed in a Tiemann dry kiln for a period of 12 days. The set 
was placed on top of a charge of oak lumber. = 3 

The temperature range during the run was from 143° to 168° F. : 
The relative humidity averaged 57 per cent during the run, with a 
range between 28 and 95 per cent. 


5 Distilled water, 1,000 cubic centimeters; Trommer malt extract, 25 Sag : agar (pow- . 
dered), 15 grams. te 


EFFECT OF KILN DRYING, ETC., ON FUNGI IN WOOL. 7 


_ The fungi were found to pe dead within the centers of all the 1- 
inch, 2-inch, and 4-inch pieces. | ‘ 


eRUN 4. 


A set of test pieces of the Neopit material was placed in a Tie- 
mann dry kiln for a period of 18 days. The set was placed on top of 
a charge of 1-inch commercial birch lumber. The temperature range 
during the run was from 135°, the initial temperature, to 180° F. 
‘The range in relative humidity was from 50 to 85 per cent. On the 
seventeenth day of the run the charge was conditioned for 20 hours 

at 180° F. and 85 per cent relative humidity. 
At the end of the run, cultures made from these blocks showed all 
the fungi to be dead within the center of each test piece. 


RUN 5. 


- 4@) Six green 1-inch sap gum (Liquidambar styracifiua) boards 
showing blue stain were subjected to 80 pounds of steam, gauge pres- 
sure at approximately 274° F., for a period of 40 minutes in a 
_Kraetzer preparator. Samples containing blue stain were cut from 
_ these boards after the treatment and forwarded from Memphis, 
- Tenn. 
Cultures made by using fragments of the blued wood taken from 
_ the center of each board showed the fungus to be dead in each case. 
(6) Six blocks of pitch pine (Pinus rigida), each measuring 1 by 
2 by 2 inches and infected with the brown-stain fungus (Alternaria 
_ sp.) were subjected to a so-called dry heat of 221° F. for a period 
of 24 hours. Cultures showed the fungus to be dead in all of the 
_ blocks at the end of the test. 
___(e) Disks cut transversely from the central part of two jack-pine 
— (Pinus banksiana) railroad ties which had been treated with creosote 
- and subjected during the treatment to a temperature of 178° to 188° 
F. for a period of 47 to 50 minutes were sent to the writer for exami- 
nation. The ties were infected before: treatment and showed - the 
_ typical stage of rot characteristic of 7’rametes pint. Disks cut from 
several untreated ties and showing various stages of the same rot 
- were also received. Cultures made from the central areas in the 
_ various disks showed the fungus to be alive in the central part of the 
treated disks as well as in the untreated ones. The treated ties were 
' 7 by 84 inches and 8 by 94 inches in cross section, respectively. 
(d) Two sets of test pieces from the Oakridge material were sub- 
jected to 20 pounds of steam (gauge pressure, 259° F.) followed 
_ by a vacuum of 1 hour. The first set was steamed for 14 hours and 
_ the second set for 2 hours. The results show that the 14-hour treat- 
_ ment killed the organisms in the 6-inch but not in the 8-inch pieces. 
_ The 2-hour treatment killed the organisms in both sizes. 


RUN 6. 


A set of test pieces from the Neopit and Oakridge material was 
_ placed on stickers in an open pile in a Tiemann dry kiln. The 
_ pieces were subjected to a temperature of 110° to 116° F. at saturated 
- atmosphere for a period of 48 hours. This set contained three 6- 
- inch and three 8-inch test pieces of Douglas fir, the pieces of each 


8 - BULLETIN 1262, U. 8, DEPARTMENT OF AGRICULTURE. 


size being infected with Polyporus schweinitaii, Trametes pini, and 
Fomes laricis, respectively. 
Upon removal from the kiln most of the pieces showed a consider- 


able area covered with mold, which had developed during the test. — 


The test pieces of Douglas fir of the 6 by 6 by 24 and the 8 by 8 by 
24 inch sizes, freshly cut, showed green-mold growth covering the 


sapwood. It is apparent that the conditions were favorable to mold a 


growth. F 

At the end of the test the cultural methods showed the fungi i in | 
most of the test pieces to be dead. Positive Sige developed : as 
follows: 


For the 4-inch pieces——blue stain in Pinus strobus and Thuja occidentalis, | 


Ganoderma tsugae in Tsuga canadensis, Trametes pini in Lari« laricina, 
Pholiota adiposa in Tilia, americana, Polyporus borealis in Acer saccharum, 
Polyporus amarus in Libocedrus decurrens, Polystictus hirsutus and P. versi- 
color in Alnus oregona. q 
For the 6-inch and 8-inch pieces—Fomes laricis and Polyporus schweinitzii — 

in Pseudotsuga taxifolia. 
RUN 7. 


Five sets of test pieces of the Neopit material were stacked in a — 
Tiemann dry kiln. Steam was turned on gradually into the kiln © 
until the recording instruments showed a temperature of 120° F. © 
and a relative humidity of 100 per cent. The test was begun at this — 
point, and this temperature and humidity were maintained. | 

A set of the test pieces was removed at the end of 3, 6, 9, 12, and 24 a 
hours. Culture blocks were cut from the centers of each of the test — 


pieces, and fragments from each block were cultured to determine the a 


viability of the fungi. “a 
The set of test pieces subjected to 120° F. at 100 per cent humidity 
for three hours upon culturing showed most of the cultures positive. | 

In the 1-inch pieces the following were positive: Blue stain in 
Pinus strobus, brown ring-rot in Thuja, occidentalis, Torula ligni- 
perda in Tsuga. canadensis, Fomes pinicola in Tsuga canadensis, — 
Fomes fomentarius in Betula papyrifera, brown cubical rot in 7’suga — 
canadensis, Trametes pint in Pinus strobus, and Polyporus borealis — 
in Acer saccharum. The following were negative: Blue stain in — 
Thuja occidentalis, Trametes pint in Larix laricina, brown cubical — 
rot in Thuja occidentalis, Ganoderma, tsugae in_T'suga canadensis, 
Fomes igniarius in Ulmus americana, brown cubical rot in Pinus — 
strobus, Fomes igniarius in Acer rubrum, and Pholota adiposa 3 in 
Tilia americana. 

The blue-stain organisms remained alive in all three sizes of test 
pieces, 1-inch, 2-inch, and 4-inch, during the 3-hour test, in the wood — 
of Pinus strobus.. The blue-stain organism in the 1-inch and 2-inch 
test piece of 7’huga occidentalis when cultured did not revive. The 
heartwood of this particular test piece was infected with a wood q 
destroyer producing a brown crumbly or cubical rot. 

In general, all the 4-inch test pieces gave positive cultures. Of 
the 2-inch pieces 13 gave positive and 3 negative results. The re- 
sults indicate that the time and temperature factors used with this 
set are not practicable in killing wood- “inhabiting ene in Linch, | 
2-inch, and 4-inch stock. j 

The set removed from the kiln at the end of six hours upon cone ; 
ing showed, in general, that the fungi were killed in all of the 1-inch_ 


EFFECT OF KILN DRYING, ETC., ON FUNGI IN WOOD. 9 


test pieces with the exception of three cases, namely, the blue-stain 
organism in Pinus strobus, the brown ring-rot in Thuja occidentalis, 
_and the brown cubical rot in 7'suga canadensis. In this set, again, 
the blue-stain organism in Pinus strobus resisted the heat in all 
_ three sizes of test pieces, 1-inch, 2-inch, and 4-inch, and in general 
it stood out as a particularly heat-resistant type of infection in com- 
parison with the rot-producing type. For the other fungi the 2- 
- inch test pieces showed positive results in 6 cases and negative results 
in c cases, and of the 4-inch pieces 13 gave positive and 3 negative 
results. 

The test pieces of the set subjected to the trial conditions for nine 
hours upon culturing showed negative results in most cases. The 
_ blue-stain organism in Pinus strobus was killed in the 1-inch stock. 
In the 2-inch stock the same organism was dead in the outer por- 
tions of the block but alive in the fragment taken from the center of 
’ the block. In the 4-inch block the organism was alive in all the 
fragments except those taken within a general area extending from 
the edge of the block to approximately 1 inch inward from the edge. 
_ All of the 1-inch test pieces gave negative results. Of the 2-inch 

stock, all but two pieces gave negative results. These were 7’rame- 
tes pint in Larix laricina (of which only one of the five fragments 
gave positive results) and blue stain in Pinus strobus. Cultures of 
the 4-inch stock showed only 5 positive and 8 negative. The nega- 
tive results in the 4-inch stock showed a steady increase through the 
3, 6, and 9 hour tests. The conditions in this trial test were effective 
in sterilizing all the 1-inch stock, nearly all the 2-inch stock, and 
only about 61 per cent of the 4-inch stock. 

The set subjected for 12 hours gave negative cultures in all but 
_ two cases. In the 2-inch and 4-inch Pinus strobus pieces the blue 

stain resisted the heat successfully. 
~ The 24-hour test was effective in killing all the organisms in all 
the test pieces. 
| RUN 8. 


Two sets of test pieces, consisting of test material from both the 
Neopit and Oakridge shipments, were placed in a Tiemann dry kiln 
for periods of six and nine hours, respectively. The temperature 
was maintained at 130° F. and the relative humidity at 100 per cent. 
Test pieces of the Oakridge shipment, 6 by 6 inches and 8 by 8 inches 
square, were used in this test. 

At the end of the test the cultural method showed that after six 
hours the fungi in the centers of the 6 by 6 and 8 by 8 inch test 
pieces were still alive. At the end of the 9-hour test, however, 
all of the test pieces, including the 6-inch and 8-inch pieces, showed 

negative cultures. : 

RUN 9. 


Five sets of test pieces of the Neopit material were stacked in a 
Tiemann dry kiln. Steam was introduced gradually into the kiln 
- until the recording instruments showed a temperature of 140° F. 
and a relative humidity of 100 per cent. The test started at this 
point, and this temperature and humidity were maintained. 
A set of test pieces was removed from the kiln at the end of 3 
hours, the second set at 6 hours, the third at 9 hours, the fourth at 


me OYga01——a : 


10 BULLETIN 1262, U. S. DEPARTMENT OF AGRICULTURE. 


12 hours, and the fifth at 24 hours. As soon as the test sets were — 
removed, 2-inch blocks were cut from the center of each piece and — 
cultures made from these. } 

In the set exposed for three hours at 140° F. at saturation all the © 
fungi were killed in the 4-inch test pieces except the blue-stain fungus 
(Ceratostomella sp.) in Pinus strobus and Thuja occidentalis, — 
Trametes pint in Pinus strobus, Torula ligniperda in Tsuga can- 
adensis, and the brown ring-rot of Zhuja occidentalis. Torula 
ligniperda was alive in the 1-inch and 2-inch pieces. These results 
indicate that in a few cases the penetration of heat into the centers 
of the 4-inch test pieces was not complete at the end of three hours, 
at least not sufficient to kill these particular fungi. The test pieces 
subjected to 140° F. for 6, 9, 12, and 24 hours all gave negative 
results when cultured. In the three-hour trial one 2-inch test piece 
infected with blue stain, when cultured, gave positive results with 
the fragment taken from the center of the block. Fragments taken — 
nearer the edge of the block, however, showed no revival of the 
fungus in the cultures. 

RUN 10. 


One set. of test material from both the Neopit and Oakridge ship- 
ments was placed in a Tiemann dry kiln for a period of three hours 
at 145° F. and at saturated atmosphere. 

Cultures made from the culture blocks at the end of the run 
showed all of the fungi to have been killed within the test pieces. 


RUN 11. 


Two sets of test pieces from both the Neopit and Oakridge ship- 
ments were placed in the usual manner in a Tiemann dry kiln. The 
pieces were subjected to a. temperature of 150° F. at saturated at- 
mosphere for a period of one hour for the first set and two hours 
for the second set. 

Of the set subjected to the above condition for one hour the 
following 4-inch pieces showed positive cultures: Polystictus harsu- 
tus and Polystictus versicolor in Alnus oregona, blue stain in Thuja 
occidentalis and in Pinus strobus, Polyporus borealis in Acer sac- 
charum, Trametes pint in Larix laricina, Fomes igniarius in Acer 
rubrum, Fomes fomentarius in Betula papyrifera, and Polyporus 
schweinitzii in Pseudotsuga taxifolia. The remainder were negative. 

Of the set subjected for two hours all of the test pieces showed 
upon culturing no evidence that the fungi were alive. 


RUN 12. 


A set of test pieces, consisting of material from both the Neopit 
and Oakridge shipments, was placed on stickers in an open pile in 
a Tiemann dry kiln. The pieces were subjected to a temperature of 
170° F. at saturated atmosphere for 40 minutes. It took 20 minutes 
for the temperature to rise from 80° to 170° F. within the kiln after 
the charge was in and the doors closed. At the end of the run all 
the fungi were found to be dead. 


BRIEF SUMMARY OF THE TEST RUNS. 


Table 1, a summary of the results obtained in the 12 runs, is based — 
upon the examination of over 1,000 test pieces and the positive or — 


EFFECT OF KILN DRYING, ETC., ON FUNGI IN WOOD. 11 


negative results of over 8,000 culture tests. The graphs in Figure 1 
are smoothed curves based upon the same data and represent graphi- 
cally the time and temperature conditions required to lall the fungi 
under discussion. _ 

Test runs 1 to 4, in which the ordinary commercial kiln-drying 
conditions were used, show conclusively that the temperatures, hu- 
midities, and periods of time were effective in killing the various 
fungi within the 1-inch, 2-inch, and 4-inch test pieces. These data 
furnish evidence which leaves little doubt concerning a phenomenon 
which has previously been accepted at its face value without posi- 
tive proof. The additional fact that all of the samples of kiln-dried 
or steamed stock infected before drying and sent in by various lum- 
ber firms for examination gave negative results when cultured fur- 


Time—Temperature Curve 


~ . 
2 based on data from steaming tests 
9 
220 
is e _I-inch stock X-4-inch stock 4 -8-inch stock 
sn O.2-inch stock © 6-inch stock a-blue stain 
uv 200 
: EE | pa aoe aa a aa 
ba) 
© 
O180 
<4 
eit ' <4 
E 140 e-)-1Ss 
bk 


ee 
= candy 


ee) || bay 
® Cot eal ci meb ae Wien Sa 
(¢) 12 14 16 » 18 20 22 24 48 
Hours 


Fig. 1.—Curves showing the time-temperature relation of the data on 1-inch, 2-inch, and 
4-inch test pieces from, the steaming tests. Data on the 6-inch and 8-inch test pieces 
are included for completeness and comparison. Curve A represents roughly the time- 
temperature relation as expressed by the data on the 1-inch pieces. Curve B represents 
roughly the time and temperature limits necessary to kill certain fungi in wood up to 
and including 4 inches in thickness. 


Neale 2 os 6 Bini) at 


nishes further evidence of the sterilizing efficiency of this method of 
seasoning lumber. 

The experimental tests, runs 5 to 12, inclusive, give somewhat 
more accurate data in regard to the effect of temperature on fungi 
in wood when acting under a constant humidity of 100 per cent. 
The effect of increasing the length of time during which the infected 
wood is subjected to a constant temperature and humidity and the 
relatively greater resistance of the larger sized test pieces to the 
penetration of heat are both clearly shown in runs numbered 6, 7, 
and 11 in Table 1 and in Figure 1. In run No. 7 the temperature 
used, 120° F., was sufficiently low to require a period of 24 hours 
before all the fungi were killed in the test pieces. This gave a fairly 
good comparison of the relative resistance to heat of the various 
fungi within the wood. 


tin various species 


Run No. 


dead, L=live.] 


different sizes. 


p. 13. ibaa run 6, Fomes pinicola was dead in Picea canadensis. 


of wood of 
Symbols used: 


Size of test 
piece (inches) 
4 
4 
4 


BULLETIN 1262, U. S. DEPARTMENT OF AGRICULTURE. 


TABLE 1.—Effect of various heat treatments on certain fung 


[For tests listed under run No. 5, see text, 


12 


“sinoy 7% | AAA 
‘smoy@t | AAA 


AAA ARA 


ARA-AAA 
AAA_AAA 
aaa aaa 


‘smoq9 | AAA 


AAR AAA 
AAA AAA 


bated Dead Ret feted eet nd fetid Partial foetal aad 
be ele nl ee len mel en le nl omen 


‘sinoye | AAA AAA AAA AAA AAA 


‘sn0y Fz | 


AAA AA AA AARA ARA 


wollen |---| --|--|--|-- |S) eee 


‘sinog@T | AAA AAA AAA AAA AAA 


‘smog 6 | AAA 


AAR AAA AAA 


‘smog 9 | HAH AAH AAH ARH AAH 
‘smoye | Hae AA HAH 


“sInoy gf 


“SABP 81 


ee) ey eed ed er ee ed ee ee ee ee Seas Ps se 


o9IT_01 OT | Pipi. | BRA BRAR 


O81 0} S&T | ARA AAA. AAA 


ee 


j 


“SACD ZI 
0891 0} o€FT | ARA AAR AAA 


“SACP OF 
o09T 04 096 | si alee 


Dice. des elit dodo) Ca 


Dultess 
D 


“SAB OT | 
oft-07-.001 | jAO8 


Fungus or rot and host. 
Ceratostomella pilifera 
in Pinus strobus---- 


Iu 


pe, oN ees | 
Vat joo 

Ry 2A | Lee 

V 24 hb 

Y 24 |-2-- 

icerente eee | ne 


Zby 10 by 48. |a-| Daj_--- 


Picea canadensis_____] 2 by 10 by 48 |---- 


in 
Polystictus abietinusin 


Thuja occidentalis_ _ 
n 


in 


Picea canadensis --___- 
in 


Picea canadensis-_-____| 2 by 10 by 48 
in 


Tilia americana. ---- 


i 


in 
decur- 


pinicola 
carnea 
sepiaria 


igniarius 
Tsuga canadensis_ -_- 


Ulmus americana--- 
Picea canadensis_____| 2 by 10 by 48 


Pinus ponderosa-_-.-..| 2 by 10 by 48 |---- 


dotsuga taxifolia_____ 
Tsuga canadensis___ 
in Pseudotsuga taxi- 
TES Se ee EE 
Acer saccharum.-____ 


Libocedrus 


Betula papyrifera - -- 
TUp GUM Sib ees 


Ceratostomella sp. 
Fomes fomentarius in 


Fomes 
Polyporus schweinitzii 


Fomes igniariusin Acer 
Fomes laricis in Pseu- 
Ganoderma tsugae in 
Polyporus amarus in 
Polyporus anceps in 
Polyporus anceps in 
Polyporus borealis. in 


Pholiota adiposa 


Trametes 
Lenzites 


Fomes 


EFFECT OF KILN DRYING, ETC., ON FUNGI IN WOOD. 18 


TABLE 1.—EH/ffect of various heat treatments, etc.—Continued. 


Run No. « 


SS ee Ss ee ee ee eS 
| ——_ | ————_ |__| ————_ 


- > > . . ) ° ° t) 
3 Size of test |= | |= | | 120 F - 140° F. OE 
Fungus or rot and host.| _: ; hess bet atz +. 
piece (inches).o. plo gle gla di we 
12 LIS PIS Bis © EE | ee ee es Nae | ee (aes 
oO lS Pl00 mina = 
SS SIV ayn sans | c 4 
Bb Tietleslos|. 12) 21 of] ol of wah sail | 
POISQIPMFSol ZA Zs cs BC 2/4415 \5) 2 jue] & 
ao fo. fo “| S/S/Sloleis/S/s/sislolo] 8 isis 
Os lo NulGeh licen len, S1O/S)qla1S/SlSie/Siaic] S |sis| g 
R po [S |e (FH [SlsleqiglSisisisiaiaigt = |4\4 
e IF fea feolalaiN|@lalajolalHln| o lala! 


—|— | — | S| — | — | — J — | | I 


Polystictus hirsutus in 
Picea canadensis_-_._| 2 by 10 by 48 [____ 


D 
Polystictus colo in} lby 4 by 24] D 2p D a Datel. - 
D 


and P. versicolor inj} 2by 4 by 24 | D D Dee ee | ele lala ta th DDL D 
Alnus oregona----_-- 4by 4by 24 | D DED se eee LA ee be o_o DH Dy 
vari) } 1 by 4 by 24 |____|____ D|D|DILIDIDIDIDI__|D|LIDID|D|D] D |D|D| D 
+rua Heniper da nl 2 by 4 by 24 |..._|.... D|D1/D|LlDIDIDIDI__DIL|D|DID|D| D |DID] D 
1 A by A by Of | | D|D/ D{LILIDIDID|__|D/L|D|DIDID] D |D|D| D 
Trametes pini in Picea 

canadensis_-_--__-___- PAI ipes lw paste sadn agile TF) Si) a Nadal lt Ah EL fc Mi a le da eis Ue] ly] i ay inet > Papen 
nee mei, Poy 4 by 24,1. :1..- D1DI|D IDIDIDID|DI__|DID|D|D/D|D] D |DID| D 

Page rink initeci| 2 by 4 by 24 |____|___- D|D/D{ILILILIDID|D/D|D|DIDID/D| D |DID 
i ep See one 4 by 4 by 24 |____|___- D|D]L{L|L/LIDID|D|D|D|D|D|D|D] D |L|D] D 
ee ae 1 by 4 by 24] D |___.|D|D | D {LIDID|D/D|__|DID|D/DI/D|D] D |D|D| D 
on aby 4by 241 D |._.| D| D| D ILILIDID|D|___DID|DIDIDIp| D [DID] D 
NT ariatcr-- | 4by 4 by 24] D |---| D | D| D j|LILID/D|D]__|D|L|/D|D|D|D| D |D|D} D 
ge eoigarnaie age Cby 6 bY 240 tas Ee LD Jig eal afl oa ee Tk) iN | A ee etl ad 
' dotsuga.. taxifolia__.\| 8 by 8 by 24 |._._}____|____|_-.. Beate tenth | Ey) Diy a) gedeaiicy |: ap Sele lias 
: : 1 by 4 by 24 |____|____ D|D!D IDIDI__|DiDI|__'DID|D|D|D|D| D |D|D] D 

op lle Hy 2 by 4 by 24 |._..1..-.|D 1D] D!LID|__|D|D)__\D/DIDID|DID} D [DID 
EeG4 sir 4 by 4 by 24 ee D|DID rag ll a D [DID] D 
: : lby 4 by 24 |____|___- D|D!I!D |DIDI__|D/D|__'DID/D|DID|D] D |DID] D 
ac hen a 2by 4 by 24 |....|....1D]D|D |LIDI__IDID|__ DIDID|DID/D] D [DD] D 
J owl by 4 by 24 /.:.. | DID! D “PPP PPP PP D DID D 
; : 1 by 4 by 24 |____|___.| Db | D ch poll piplp pip PADI... 
token peer a aby 4by 2410 | DP ILIL ID Dip p pIpIpIpI b Ipipia22 
ug: ---|| 4by 4 by 24 |____|____| D | D J____|L|L/L|D|D|__|__[DID|D|DID] D |D/DI_--- 
5 : 1 by 4 by 24 |.-__|___.| D}] D |____|L/LIDIDIDI__|__|DIDIDID|DI____|D/DI___- 

Brown ring-rot in 

, om Res 2 by 4 by 24 |____|____| D | D |--_-|L/LID|D|D|__|__|D|D|D|D|D/____/D|D]___- 
Thuja eezets | 4by 4 by 24 |__| D|D L/L D/D/D/-| | D|DIDIp|—- Dip 


Minor preliminary tests were included under run No. 5, a, b, ¢, 
and d. The test given in 5,a, indicates that the steaming process, 
where pressure is used for short periods of time, is effective in 
killing the blue-stain fungus, at least in 1-inch stock. The steriliz- 
ing effect of the ordinary method of oven drying blocks of wood 
is given under 5,b, and the data on the failure of a particular pre- 
servative treatment in sterilizing the center of 8-inch ties infected 
with a heart rot is given under 5,c. It was noted that in the areas © 
where the creosote had penetrated the infected wood the fungus no 
longer revived when cultured, but revived in cultures made by using 
fragments taken from the untreated portions near the center of the 
ties. From the face of the tie to a point 2 inches in from the face 
no positive cultures were obtained from the infected area; beyond 
this point and toward the center, positive cultures were obtained. 
The heat apparently was effective in sterilizing to a depth of 2 
inches. Under 5,d, it was found that a steaming treatment of two 


#7 


14 BULLETIN 1262, U. S. DEPARTMENT OF AGRICULTURE. 


hours followed by a vacuum of one hour was necessary in order to | 
sterilize to the center the 8-inch test pieces. 


e 


AIR-SEASONING EXPERIMENTS. 


In the first air-seasoning experiments infected planks 2 by 10 
inches and 4 feet long cut from spruce (Picea canadensis) pulp 
logs were used. These planks contained. typical and incipient 
stages of the decays produced by Lenzites sepiaria, Trametes carnea, 
> Late anceps, Trametes pini, Polystictus abietinus, and /omes 
pinicola. | . 

On July 28, 1920, 21 planks representative of the above material 
were stacked in the yard of the Forest Products Laboratory. The — 
open method of stacking was used, and the layers of planks were ~ 
separated by half-inch stickers. Adjacent to this pile another pile 
containing 33 planks was constructed. In this case the planks were 
closely piled one on top of the other. A third set of 39 planks of 
the same material was stacked open piled, while a fourth set of 
28 planks was stacked close piled in a well-inclosed shed. 

On June 11, 1921, records were taken concerning the number and 
species of fungous sporophores developed upon the planks since 
the piles were constructed. The open pile in the yard showed a total 
of 41 sporophores, of which 35 were Lenzites sepraria and 6 were 

Trametes carnea. 'There were 23 sporophores on the planks in the 
close-piled set, and of these 13 were of Lenzites sepraria, 2 were 
Trametes carnea, 6 Polystictus abietmus, and 2 Polyporus an- 
ceps. Most of these sporophores were of small size, but capable of 
producing spores. Many of the smaller of these dried out per- | 
ceptibly during the warm, dry weather, but revived again during 
the prolonged rainy periods. Most of the sporophores appeared 
during the spring months. It is interesting that the largest number 
of sporophores were found upon the open pile and that of these 
over 85 per cent were of Lenzites sepiaria, a fungus which thrives 
under comparatively dry conditions. In the closed pile only 56 
per cent of the total sporophores were of Lenzites sepiaria, and 
three other species were represented, in contrast to two species in 
the open pile. a >. 

Cultures made from test blocks cut from the planks stored in the 
two piles m the shed showed that the fungi within the wood were 
still alive, although there were no indications that the decays had 
progressed within the planks. No sporophores had developed on 
any of these planks. . 

On April 25, 1922, notes were again taken on the sporophore crop 
appearing upon the planks stacked in the yard. On the planks in 
the open pile a total of 61 sporophores were noted. Some of these 
were resupinate in character, and a few were buttons, or rudimentary 
fruit bodies. Of this total, 50 (or about 82 per cent) were Lenzites 
sepiaria, 7 Trametes carnea, 2 Polyporus anceps, and 2 Stereum sp. _ 
On the closed pile were found 69 sporophores with about 10 buttons. 
Of this total, 42 (or about. 61 per cent) were Lenzites sepiaria, 13 
were 7rametes carnea with 10 buttons, 7 were Polyporus anceps, 5 
Polystictus abietinus, and 2 P. versicolor. BS 

A comparison of the closed pile with the open pile indicates that 
the closed pile is more favorable to sporophore production and pre- 


EFFECT OF KILN DRYING, ETO., ON FUNGI IN WOOD, 15 


sumably to decay activity. The records taken on April 25, 1922, 
show an additional genus and two additional species over those take 
on June 11, 1921. ; 
As an additional control, a closed pile was constructed in the yard 
on July 28, 1920. This was made of the infected planks removed 
from the kiln (run 2) which showed by culturing that the fungi in 
the wood had been killed. This pile was subject to the same environ- 


_ ment as the other two piles in the yard. No sporophores developed 


upon these planks. 
REVIVAL OF FUNGI IN WOOD AFTER AIR DRYING. 


Green infected lumber piled for air seasoning or for storage con- 
tains the live organisms which cause rot and sap-stain. ‘These or- 
ganisms can remain inactive in wood during periods when the lumber 
is kept dry, but can revive and con- 7 
tinue their development and there- 
fore extend the decay or stain in 
the presence of favorable moisture 
and temperature conditions. The 
approximate length of time during 
which wood-destroymg and sap- 
stain organisms can remain alive in 
wood under continued air-dry con- 
ditions has been determined for 
certain fungi by means of the 
method here outlined. 

Blocks of wood infected with 
known fungi were stored on shelves Fie. 2.—An old fungous thread (hypha) 
: : : of the blue-stain fungus which has 
in the dry air of the laboratory, in Puvledd and produced-tirds ‘new’ etdw- 
mien tne temperature range was... 2g branches The hyphe in the wood 


(Pinus strobus) were air dry and 
between 64° and 74° F. Cultures dormant for some time, but revived 


were made at intervals, usually six  Ynlarsea'about 800 times) puDPled. 
months apart, using fragments of 

the infected wood. Positive cultures indicated the revival of the 
fungus in each case. In order to determine whether the new growth 
developing from the infected fragment grew from the old hyphe in 
the wood and not from spores, either secondary or primary, or from 
young hyphe of a possible recent infection of the wood, cover-glass 
cultures were made. Thin sections of the infected wood were cut, 
washed in distilled water, and under sterile conditions placed under 
a cover glass on a thin layer of malt agar on a glass side. Here the 
growths of the hyphz were observed under the microscope. In all 
eases the new growth was traced to the “sprouting” of the old 
hyphe in the wood (fig. 2). This was observed for the following 
fungi: Trametes carnea, T. pini, Polyporus anceps, Trametes serialis, 
Fomes pinicola, and Ceratostomella sp. 

The results given in Table 2 show the cultures completed up to 
_ January, 1923. 


‘The blue-stain fungus in one case was estimated to have remained 


more or less dormant for a period of seven years. Z'rametes serialis 
(?) in a Douglas fir timber was found to revive after use of the 


‘ 


geen 
Ngee a 
16 BULLETIN 1262, U. 8. DEPARTMENT OF AGRICULTURE, = hg 


timber in a building for 44 years and subsequent storage in the Iba 
ratory for over 7 years. Complete records on Polyporus amarus in — 
Libocedrus decurrens showed that the fungus remained alive up to — 
about. eight months. Cultures made from the infected wood one 
month and eight months later showed no growth. Cultures of thin | 
fungus develop Slowly when fragments are taken from material not — 
freshly cut from the tree or log. In some cases 20 to 25 days elapsed — 
before the growth appeared on the agar slants or the inoculum. 

The fungi recorded in the “ Live” column are still under observa-— 
tion, and in no way can these results be taken as the limits of vitality — 
of the different fungi. The figures in the “ Dead” column indicate 
only that the fungus did not revive when cultured. Just when the 
ability to revive was lost has not been determined. 


TABLE 2.—Length of time certain fungi remain alive but inactive in wood stored 
in the air-dry conditions of a room. 


[Date when last cultured, January, 1923. ] 


Length of time in storage, air-dry 
condition. fr 
Fungus. Host. Live Deal 
Years. | Months. | Years. | Months. 
Ceratostomella sp___....-_.--._- Pinus ‘ponderosa: (4422-22. et 3 Q |32325°E th Cage 
IPG. Boe St ee ae ae os 0 Pinus strobuss.22. 2.) Fes 3 i ee Bes || ae LS aS 
Done oie? ee Sa Southern yellow Par Ld rida 7 0 |). eee 
Echinodontium tinctorium ______ Tsuga heterophylla_____________ 5 yA ee: Sete | ee Ee) CELT 
Fomes annOSUS= | 4c eee ; |; rene, pita ica Dak emlialyoens: |e 5 07 
Fomes applanatus--_-_..-.----.-- Populus trichocarpa____..._____- I 5 2 4 
Pomesigniarius—....- 2.2. --- 228 A Cer PUDTAM 45.2 2 ee 1 Bal _ cc ee Seen 
Gs. eee sehen Oe oe Populus tremuloidés //_ i220. LE ae ee 10 
Fomes laricishsgao enue foe Pseudotsuga taxifolia____._______ 1 | Sj ree am PE 
Fomes:pinicola.._...2<+ 03.30. Tsuga heterophylla-_--__-__.-_-_- 1 ge os See gt Ay | 
Tpeneten Fst 0 ot. Vea Sea Bt ell Ne rie caniadensisces: . ivi ye ees ; Tee hy tte ee oe 
eGR oe. ranteatitey et Robes Mot es ‘a a ee IE DO LS APS ae ey ie 
Gakoactun SSAC a 2 ee Tsuga eanadensis.t: //. {ti 22 | site 6 1 3°49 
Lentinus lepideus_._-_.-_.---.-- Southern yellow pine...f-.'% .-_ |" 5 eee 2 5 tt 
Benge sepiatigg 22 = ster oa 2 Sea ee ee 2 Fi ee paint Sc and 
Wee a ee ea ee tee “Picea canadensis.__-__._-----__- 2 Oreos 52 cle Ae 
ae ERR: peo Si CHR prea AN PUSS | EINE ee oe do paca er (oe IS. wn.oel om cert et 2 6 2\ Pee eee, ee 
AE ee ee ee ae Se do... 5-2. TR a TS 6 SS ELE SER T ones 
Pholiota adingsa : = eee This AMeTICgO. af ip coed 1 Bt sh See eee, 
Ee Eee eee Mies Crandis? 227 LI Se ee 6 3 
Pholiota | eee eeee meres ert ee O9ecoreectols.¢43-<ped eee 6 O ioe: oer eet 
Polyporus adustus___.._.___-___- INVssa'sylvatica oo ee mh 1 8 2k ee ; 
Polyporus amarus____.___---___- Libocedrus decurrens_ __.-2-212-)--LL.-22 (im mee Es a Ts 8 
Polyperus anceps....... 22... Picea canadensis _-.-...-.....--- 2 4 hs ete ee Ek 
PO. eee) Fe SOS ee ey eae Pimis*pondtrosa': £2 552 ates esas) 3 SPE BEV eee 
Polyporus schweinitzii______.___- Pseudotsuga taxifolia__......__-- 1 Ouislcpetck)| Sy eee ex 
Polyporus stipticus_-_..-...-_-__ Pinus QOBGErOSA . ~~ 2 eae eee 2 1) 2 2 eee ne 
—- sulphureus:+ - 2222-22 Quercus Spi2>. 2.4 Ine ie 1 4A eae 33 
SORES. ok Peete See Ge TS Queress rubra. _ig.-.. oul 10 0 
Polystictus versicolor_______-_-_- Ainus orepomias° °°) 2° S28bex 22 2 O4t + 35)! Aes. 
Polystictus hirsutus --_....-.---|----- BD: sce Ab es ces. -F a5 tees 2 6H ae 
Wrameres Dill tase =~ soe nee Lari RiGee =. ae eee 1 1 Pn arte Oa 
1b); Seen 20a eee eee ees amt Picea canadensis -_____._-_---_--- 2 3 DO as ete 
Gm ee eee eh Tanah Pinus monticola¢ =e 2 | eee ee 5 0 
Mya FEL! Bs See ee AS Tsuga’heterophy Ha. Pk). 222 Ae ee 7} 2 
Trametes serialis (?)__..-._--.._- Pseudotsuga taxifolia__._________ i pp | Sees be Wag orig ee 
Fusarium negundi (red stain)___.| Acer negundo_________.__-_____- 1 6 eo eee 
Brown cubical rot.__.-_-.-.-..-- Thuja phieptat \G- 3 oe Ga 1 6 Loess ees 
DO. ee ee ee Thuja occidentalis. _____________ 1 6 |. |e 
Brown pocket rot__.__....-_-_-_- Sequoia sempervirens -__-_____-.- 5 O22 AT eee, 


In general, the results at 4 time show that. certain peat in eee 
can remain alive though dormant for long periods under the areas 
conditions of a room and are capable of reviving and producing new — 
growth when sufficient moisture is added. 


EFFECT OF KILN DRYING, ETC., ON FUNGI IN WOOD, 17 
REVIEW OF THE RESULTS. 


Sterilization by heat is a well-known process and has its examples 
in many everyday activities. The canning of fruit is probably the 
best-known example, and it is but a short step from this to the 
sterilization of wood—a. very similar process. The protection of 
wood against. future infection is not accomplished by sterilization 
alone. Proper care following sterilization is absolutely essential, and 
in the case of lumber proper storage to insure dryness is the process 
by which reinfection is prevented. This fact has prompted the in- 
shist in of the air-seasoning data for correlation with the results of 
the heat experiments. It will be of interest to note here that wood 
when properly kiln dried is equal in strength to air-dried wood when 
moisture contents are carefully considered (0). 

A brief consideration of the factors affecting the penetration of 
heat. into sound and infected wood may not be out of place here. 
Very little has been published on this subject. Hunt (3) in a series 
of experiments obtained data on the rate of heat penetration into 
sound wood of various sizes and species. Using sawed ties of maple, 
red oak, loblolly pine, and hemlock 6 by 8 inches by 84 feet he found 
that under the conditions of the experiments no appreciable dif- 
ference in rate of increase of temperature due to difference in species 
could be determined. He also observed that. the interior of the ties 
never quite gained the temperature of the heating medium and that 
seasoned ties heated more rapidly than green ties. In the treatment 
with steam at 20 pounds pressure the time required for the interior 
to reach 212° F. varied from 2% to 5 hours, averaging 4 hours and 
20 minutes. With steam treatment at atmospheric pressure the ulti- 
mate maximum temperatures within the ties varied from 2 to 17 
degrees F. less than the temperatures of the surrounding medium. 
With ea at 20 pounds pressure the variation was from 2 to 21 
degrees F’. 

n regard to the experimental data in this bulletin, the effect of 
heat upon the fungi in the wood was observed to vary with the size® 
of test pieces and the relative porosity of the wood as expressed by 
the stage of decay. In many cases negative cultures were obtained 
from portions of the culture block, showing a typical stage of decay 
which was obviously more porous than the near-by areas of incipient 
decay. In other cases the blue-stain fungus present in the sapwood 
of the piece was killed in blocks showing a brown cubical or brown 
ring-rot in the adjoining heartwood, and it remained alive in blocks 
of similar size containing only incipient stages of decay in the 
adjoining heartwood. The data on the steaming experiments when 
plotted on coordinate paper show in general a definite relationship 
between time and temperature. This is clearly evident in the curves 
shown in Figure 1. Curve A is drawn through points representing 
data on the 1-inch test pieces. Curve B is more or less theoretical 
and represents roughly the time and temperature limits necessary 
to kill certain fungi in wood up to and including 4 inches in thick- 
ness. The point in Figure 2 showing death of the fungi in 4-inch 
stock subjected to 140° F. for six hours is considerably outside the 
curve and theoretically should coincide with the curve near the 44- 
hour point. It is evident that the fungi in this case were killed 


18 BULLETIN 1262, U. 8, DEPARTMENT OF AGRICULTURE. © = a | 


before the six-hour limit was reached, as another test (run 10) chime 7 
that the fungi were dead in the 4- inch stock subjected to 145° F. for 
three hours. For completeness, the points representing the data | 


on 6-inch and 8- inch stock, as well as the high values obtained for. q | 


the blue-stain organisms, are given. 
In the steaming experiments a saturated atmosphere was usdih in 


order to avoid as much as possible variations in heat penetration 


which might be due to variations in moisture content of the test — 
pieces, since the experiments of Hunt (3) have shown that seasoned 
wood heats more quickly than green wood. The data from the — 
steaming experiments are thus directly applicable to the preliminary ~ 
steaming now generally recommended for various commercial kiln 
runs. This preliminary steaming consists of subjecting the wood at — 
the beginning of the run to live steam (160° to 185° F.) for half 
an hour to three hours. By glancing at the temperatures and periods 
of time given in Table 1 and comparing these with the temperatures 
and periods of time given for the hardwood and softwood drying 
schedules by the Forest Products Laboratory (1, 4, 11) it will be 
seen that with very few, if any, exceptions the heat and periods of 
duration of each schedule are sufficient to sterilize wood (for the 
fungi of these experiments) up to and including 4 by 4 inches in 
cross section. In the drying schedules for hardwoods the lowest 
temperature used is 115° F. for an average period of 56 days and the 
highest temperature 170° F. for 3 to 4 days. The lowest isd highest 
temperatures used in the various schedules for drying softwoods are 
135° and 200° F., respectively. The lowest temperature used in 
the steaming experiments was 110° F. for 48 hours; the highest was 
170° for 40 minutes at atmospheric pressure and 274° at 30 pounds 
gauge pressure. The first is successful in sterilizing wood up to 
but not including all the test pieces of a thickness of 4 inches; the 
last has been tested for 1-inch stock only. 

From the experimental data obtained in this study the ipomyne 
results are shown for the hosts and fungi studied: 

(ly. x long list of fungi consisting of both wood-destroying and Seip 
organisms in a variety of hosts can effectively be arrested in their development 
through sterilization by heat. 

(2) The blue-stain fungus is apparently the most resistant of those tested. 

(3) The stage of decay of certain fungi may affect the rate of heat pene- 
tration within infected wood. 

(4) The temperature of commercial kiln runs, excepting temperatures below 
120° F., are effective in sterilizing infected wood up to and including 4 by 4 
inches square. Pieces 6 by 6 inches and 8 by 8 inches square were sterilized 
by treatment at 130° F. for nine hours at saturated atmosphere and by igs vol 
pressure treatment. 

(5) Infected wood piled in the yard at Madison, Wis., in both open and 
closed piles and unprotected against rain, will continue to develop decay and 
in many cases fungous fruiting bodies. 

(6) Similar material piled in dry sheds protected from moisture showed 
no outward signs of fungous activity, but the fungi remained alive though 
inactive. Uninfected wood in the same shed remained sound. 

(7) Certain fungi dormant or inactive within air-dry wood for long periods. 
of time are capable of reviving and continuing their development be aap the 
return of favorable moisture conditions, 

One investigator (72) has shown that a fairly high moisture con- 
tent of the wood, about 25 per cent, is needed before spores of Len- — 
zites sepiaria will germinate readily upon the surface and subse- 
quently cause infection. 


EFFECT OF KILN DRYING, ETC., ON FUNGI IN WOOD, 19 


Miinch (4) has shown that for a blue-stain fungus (Ceratostomella 
coerulea Miinch) in the sapwood of Scotch pine (Pinus sylvestris 
L.) the optimum moisture content of the wood lies between 33 and. 
74 per cent, based upon the oven-dry weight. Above and below these 
limits the activity of the fungus spielen. and at 143 per cent no 
_ growth was noted. At 28 per cent little growth was evident. The 
same writer also states that the moisture content favorable for the 
blue-stain fungus agrees in general with the moisture requirements 
of certain wood-destroying fungi. 

_ Snell (7) has reported on one series of experiments in which he 
used Lenzites sepiaria, L. trabea, Trametes serialis, Fomes roseus, 
and Lentinus lepideus in loblolly-pine sapwood (Pinus taeda L.) 
and Sitka spruce (Picea sitchensis), presumably heartwood. He 
found that the results upon loblolly-pine sapwood agreed very closely 
with those of Miinch on Scotch pine. Very little decay was recorded 
when the quantity of water in the wood was below the fiber satura- 
tion point, a moisture content of 25 per cent in terms of the oven- 
dry weight of the wood. With the increase in moisture content the 
decay increased, and the greatest development of decay occurred 
between 33 and 42 per cent (or 49 and 72 per cent based on the 
oyen-dry weight). At 50 per cent there was little decay, and no 
decay was noted at 60 per cent (150 per cent, oven dry). With 
spruce the decay began a little below the fiber saturation .point, and 
the greatest development was noted between 30 and 57 per cent (43 
and 133 per cent, oven dry). At 67 per cent (203 per cent, oven 
dry) neither penetration by the hyphe nor decay was noted. 

These experiments indicate that a moisture content considerably 
above the fiber saturation point of wood is required for the optimum 
development of at least certain fungi within wood. How long 
this optimum condition must be maintained to produce decay in 
stored lumber is not known, nor are there any figures to show 
whether alternate wetting to the fiber-saturation point and above 
and drying to 17 per cent and lower is favorable or unfavorable to 
fungous development. In regions where the rainfall is heavy and 
continuous over long periods the unprotected and poorly protected 
lumber would unquestionably develop wood-inhabiting fungi. It 
is doubtful whether lumber properly dried and carefully stored 
under cover would absorb sufficient moisture from a humid atmos- 
phere to sustain continuous fungous growth within the wood. 

With these facts as a basis, it seems reasonable to suppose that 
wood properly kiln dried will be sterilized and that if it is then 
properly stored in dry well-ventilated piles protected from all mois- 
ture (except the moisture absorbed from the air) the stock will re- 
main bright and sound. 


SUMMARY. 


The need is shown for some practical method or methods of 
sterilizing wood against the fungi inhabiting it, and the wide appli- 
cation of such methods to the wood producing and consuming indus- 
tries is indicated. 

The tests carried out show that a long list of wood-inhabiting 
fungi in a variety of woods can effectively be arrested in their de- 
_ velopment through sterilization by heat. 


20 


BULLETIN 1262, U. S. DEPARTMENT OF AGRICULTURE. 


Of the various fungi tested the blue-stain fungi appear to be the 
most resistant to heat. No great differences in resistance were noted. 
among the various rot-producing fungi tested. 

Commercial kiln conditions and steaming processes coming within 
the effective limits of temperature and time as determined by the tests 
are effective in sterilizing infected wood up to and including pieces 
4 by 4 inches square. Pieces 6 by 6 and 8 by 8 inches square were 
sterilized when subjected to 130° F. for a period of nine hours. 
Sterilization was also effected by steam-pressure treatments. ra) 

Methods of piling and storage are important factors in ‘protecting 
wood against deterioration due to fungi. 

Certain fungi continue to develop in wood as long as favorable 
conditions are present, and they will revive and continue development 
after long periods of drying. 

From the data obtained it is assumed that wood that is properl 
kiln dried will be sterilized and that with proper storage it will 
remain bright and sound. 


(1) 


(2) 
(3) 


(4) 


(5) 


(6) 


(7) 


(8) 


(9) 


(10) 


(11) 
(12) 


LITERATURE CITED. 


Brewster, D. R. he ati 

1919. Schedules for drying hardwoods. In Hardwood Rec., v. 47, 
no. 6, p. 19-21; no. 8, p. 20-22a, illus. . 

Hoxir, F. J. 

1915. Dry-rot in factory timbers. Ed. 2. 107 p., 70 fig. Boston. 

Hunt, GEORGE M. 

1915. Temperature changes in wood under treatment. In Proc. 11th 

Ann. Meeting Amer. Wood Preservers’ Assoc., p. 85-99, 7 fig. - 
LouGHBOROUGH, W. K. , 

1922. Schedules for drying softwoods. In Southern Lumberman, 

v. 105, no. 1385, p. 51. 
Mutncu, ERNST. 

1907-8. Die Blaufaiule des Nadelholzes. In Naturw. Ztschr. Land. u. 
Forstw., Jahrg. 5, p. 531-573; 6, p. 32-47, 297-823, 33 fig. 
Bibliographical footnotes. 

SiecGers, PAu V. ot 

1922. Torula ligniperda (Willk.) Sace. A hyphomycete occurring in 
wood tissue. Jn Phytopathology, v. 12, p. 369-374, oe “25. 
Literature cited, p. 374. 

SNELL, WALTER H. 

1921. The relation of the moisture content of wood to its decay, with 
special reference to the spraying of log piles. In aoe and 
Paper Mag., v. 19, p. 531-538, 2 fig. bs 

1922. The effect of heat upon wood-destroying fungi in mills. In 
Proc. 18th Ann. Meeting Amer. Wood Preservers’ Assoc., p. 
25-29, 1 fig. 

1922. The effect of heat upon the mycelium of corte structural tim- 
ber destroying fungi within wood. (Abstract.) In Phyto- 
pathology, v. 12, p. 59. 

Unirep STATES DEPARTMENT OF AGRICULTURE, ForEST SERVICE. FOREST 
Propucts LABORATORY. 

1922. Comparative strength of air-dried and kfln-dried wood. U. S. 
Dept. Agr., Forest Serv., Forest Products Lab. Tech. Note 
180, 1 p. 

1922. Drying periods of various woods. S. Dept. Agr., Forest 
Serv., Forest Products Lab. Tech. Sia 107, 1 p. . 

ZELLER, SANFORD M. } 

1920. Humidity in relation to moisture imbibition by wood and to spore 
germination on wood. Jn Ann. Mo. Bot. Gard., v. 7, D. 51-74, 
5 fig., pl. 1. Literature cited, p. 72-73. 


WASHINGTON : GOVERNMENT PRINTING OFFICE ; 1924 


ae 


CONTROL OF DECAY IN PULP AND PULP WOOD 


By Orto Kress, formerly in charge, Section of Pulp and Paper, Forest Products 
Laboratory; C. J. Humpurey, Pathologist, and C. A. RicHarps, Assistant 
Pathologist, Office of Investigations in Forest Pathology; M. W. Bray, Chemist 
in Forest Products, and J. A. Sraipu, Assistant Engineer in Forest Products, 
Forest Products Laboratory, Forest Service, in cooperation with Bureau of Plant 
Industry 


CONTENTS 

; Page 
mero: dooney propel in pulp industry... -- = eh kk n 
terme eee a2 fk fits eg h var de eyer Pi on Poel eet zeus oli sese. don 4 
ee tenet y TOT COW LM Offline] 22.2 =. 5-4-2 Soe ee nek nee es a 5 
Fungi that decay stored pulp wood-_-____...-_-_-_- SE EL OP FED PERE Ee LIS 9 5, SUE gee 6 
ENS EE ES ae Mere Oe ae eS Se ee ee ee on ili Soak 6 
Umea wood AV alg ble 1Or MUNpINe 8 ee ee ee EN 6 
error meriod) i fin® Pires niyeek a1 Pegs moe Tk eee sen oes ete! cece OL 7 
Handling of pulp wood at woods points______-______ COR pan Al hee Ta amacrine ets Si 7 
Pit yr HOUeah tie THT Vs el ov es PU er Po A oo ee ari ee a 8 
I RETMTOTIOALIONR a5 2230 Ue sc eh dee BBA ec case aed be ie coane ck Se ste den seus 12 
Pepe enneaicverishics of decayed WO0dS.... 02622 20 ee ee 14 
Physical properties of mechanical pulp made from sound and from decayed spruce-.__...----_- 14 
Physical properties of sulphite and soda pulps made from sound and from decayed wood_.__-_- 16 
Chemical properties of sound and decayed woods and pulp from sound and decayed spruce---.-- 20 

parece woedand sprice mechanical pulp... 260. 2 ee Pe eee teen + -ae 2 
Pin ISAt ANC ASPel WOOGS..._. 2 rd oe ee a ee ae ke 23 
ETERS MATEO [) 134 92 90) (Rita Mee Ws eee red to 8 gee ee, dee lad ee 24 
NRRL UNE ent ee ee ee ak ee ceeds 24 
Pippeooussion of Chomlical data... ls) co be cre ee eee 25 
EE EELS EE EE Ee On Pn eee SE a ee Oe ee A 25 
See Rr ee Ps ee ESR PA ns SERA OOS | of Pe ee 26 
ann eCOTaAgee De ert. uke co ee) yy Sule de WO Vesela he eee 26 
eee reperties Of Ddlp decayed in Storage.....___.-_.-._.___-+--._-----------s+-_-------------- 29 
Preservauonor piip by chemical treatment... a ge eb LL ees alee 31 
Sn MPMEVOM I OLOLSY sec et fo a eR ee a 32 
aR UCERTERUINTOETICOI EIT ne ee FEI APART ENO SND RS GPP Rate sik feds 33 
Pee aemrerervative treatments _ 422213. ss Ssec sess secu as eee ea eeee sue 54+ ---- see kee... 36 
Preservatives recommended for mill application__.._..._......_..._..--....---.---------------- 48 
I ae See cr 6h a Sa a Ue eb sll 49 

APPENDIX 
Biucies of specinetungi that. deteriorate wood pulp......-.i---.-..---L2---.----. se s--- 52 
ar OUSTICHLONS, U2 et eee Oe EN RS a ah 52 
Deere en nonods eniployed. . 2.2.6.2. 20 sues cue pes esis Lees 2b sa petal. d--- 56 
I a eB ne ge pene bo peda alll i Ai ite tact Caged tie Op 56 
pag and chemical properties of ground-wood pulp deteriorated by specific fungi in pure cul- 4, 
Se ee er cee ee 

RIPE OS ok S| ot SS ee A ad Gal is BRAS MS 2 B45 3 £87! 67 
Ho OTC Sa it 2 ole Wee INE BS SNE ME UNy cree ah UUs ey get lg ce cv) Sgt ne ar, aR Cee 74 


ag aul ase Sige lh 5. ees 2 ahaha Sale dat glide te alien ed 79 


IMPORTANCE OF DECAY PROBLEM IN PULP INDUSTRY 


The pulping of wood for the production of paper and various fiber 
products is one of the major industries of the United States. It is 
argely concentrated in the northern region beginning with Minnesota 


_ and extending eastward. The six leading pulp-producing States 


523°—25t——1 


a Se 
y) ‘BULLETIN 1298, U. 8. DEPARTMENT OF AGRICULTURE 
are Maine, New York, Wisconsin, Pennsylvania, New Hampshi A} 
and Minnesota. Thirty per cent of the newsprint-manufacturing | 
industry is in New England, nearly 50 per cent in New York, and 15 | 
per cent in the Lake States. . 2 
Statistics (20)! recently published will give some idea of the magni- | 
tude of the operations. During 1920, 253 establishments reported the | 
use of 6,114,072 cords of wood valued at $116,495,720, with an 
average cost per cord of $19.05 f. 0. b. mill. This material produced 


3,821,704 tons of pulp, of which 1,583,914 tons were meee 
1,585,834 sulphite, 463,305 soda, and 188,651 sulphate pulp. The 
pulp wood prea ption in 1920 showed an increase of 16 per cent | 
over 1918. This demand was met in part by the importation of © 
nearly a million and a quarter cords of spruce and poplar. ¥ 
An abnormal demand for pulp developed in 1919, because of the — 
world shortage following the war, and this continued until the latter | 
part of October, 1920. Wood and pulp increased correspondingly ~ 
in value, and losses from decay and mold, assuming greater monetary 5 
significance, came sharply to the attention of operators and evoked Pt 
many requests for assistance in controlling or reducing the losses. © 
The Federal Government did not have funds immediately available 4 
to finance the necessary investigative work, and a group of 33 inter- © 
ested mills subscribed to a fund which enabled the Forest Products — 
Laboratory to employ two pathologists (who were detailed from the © 
Bureau of Plant Industry) and two chemists to study the problem. — 
A preliminary survey of the situation was made at some twenty | 
of the cooperating mills in Wisconsin, Minnesota, New York, and — 
Pennsylvania. At these mills the problems were discussed with the | 
operators, and inspections were made of wood and pulp storage © 
facilities and methods. The survey disclosed heavy losses at — 
most mills, particularly in the storage of wood, and past losses of ~ 
considerable extent in the storage of ground wood pulp. One mill © 
had lost more than $100,000 on ground wood stored inside for a — 
comparatively short time. At another mill a loss exceeding $10,000 — 
occurred in a 7,500-ton lot of hydraulic-pressed ground wood from | 
Canadian spruce stored for two or three years. ‘This was in an out- | 
side pile about 20 feet high, unprotected above but placed on a plank © 
foundation. ‘The company reported this pulp about 72 per cent air © 
dry (65 per cent oven dry). There were also several instances in ~ 
which ground wood, infected at one plant and shipped to another, — 
had rotted very rapidly after arrival. Such direct cancellations of — 
unsalable pulp from the books create a very distinct impression of — 
loss; but there is a much greater loss, in the aggregate, from deterio- 
ration which is not sufficiently marked to cause rejection, though — 
sufficient to reduce the market value of the product. All these afe- . 
ments the present investigators have tried to take into account. 
Little attention has been paid in the past to losses from pulp wood ~ 
rotting in the yard or in the woods. Rot has been recognized only ~ 
after it became sufficiently advanced to affect the strength of the pulp, 
thus necessitating a larger proportion of sulphite to produce news- 
print. In only one instance was wood found which was so far — 
rotted as to be considered unfit for use. This had been in storage — 
about four years. Many mills have been operating for years on — 


1 Numbers in italics in parentheses refer to literature listed in ‘‘Bibliography,”’ p. 80. 


CONTROL OF DECAY IN PULP AND PULP WOOD 3 


| wood with a considerable admixture of decayed material, so that a 
' “normal” yield with them is not the normal for sound wood, and 
| losses figured on that basis would be underestimated. In fact, 
| definite data on comparative losses in pulping sound and infected 
'.woods, either by mechanical or chemical processes, were lacking. 
_ Decay in the wood yard was considered rather an “‘act of Providence” 
than a direct result of storage conditions highly favorable to the 
growth of wood-destroying fungi. 
Since the improvement of storage conditions in the wood yard and 
| the working out of a method for the Sacnher ag of ep by the 
| addition of antiseptics appeared to be the two problems of greatest 
significance, it was ecified to direct the investigative work especially 
along these lines. 
_ The present study, however, combines investigations on all phases 
of the Pe iotation problem. Rarely is the opportunity offered, as 
in this case, to correlate mill tests and commercial practice with 
_ pathological and chemical laboratory investigations of the same 
material. It is the ideal way to conduct a commercial study. 
_ The investigations cover the cause of decay in wood and wood + 
pulp and the conditions which favor it. This information, when 
_ adapted to commercial practice, will go far toward reducing deteriora- 
tion in these products. 
The pulping characteristics of decayed wood have been investigated 
with special reference to the losses actually occurring under present 
commercial methods of storage. Pulping value depends to a large 
degree upon the nature of the process used. With decayed wood as 
raw material, mechanical pulp is characterized by low yields, dark 
color, and to some extent low strength; soda pulp by high consump- 
tion of chemicals, low yields; and decidedly low strength. Sulphite 
ulp, on the other hand, unless made from wood badly deteriorated, 
bes characteristics not greatly different from those of pulp made from 
sound wood. The yield, when‘expressed in terms of weight of both 
wood and sulphite pulp, is not materially lower, although the pulp is 
slightly darker and becomes somewhat brittle when beaten. When 
the wood has become badly decayed, however, the deterioration is 
reflected more positively in the characteristics of the pulp. 

In order to determine the relation between decay and pulping 
value, it was necessary to study the subject from both a chemical 
and a pathological angle. The investigations show that the changes | 
in the wood substance leading to poor quality and quantity of pulp 
are due to a physical breaking down of the fibers Jiigatirpaii ae ye 
_ chemical changes in which even the cellulose is finally changed from 
_astable form to an unstable condition more soluble both in water and | 
eet use 
__ By the application of known principles of sanitation and rotation 
it is possible to reduce materially the losses which result from decay 
during the handling and storage of pulp wood. It is not feasible, 
. however, to eliminate entirely from the mill all the pulp wood which 
has become decayed. The rapidity with which the pulp wood 
supply in the United States is vanishing makes it imperative that 
even the decayed wood be used wherever economically possible. 
_ Many trees are attacked by fungi and begin to rot while they are still 

on the stump, especially those which have reached maturity or those 

which have suffered from attack of insects, from suppression, or from 


- 


4 BULLETIN 1298, U. S. DEPARTMENT OF AGRICULTURE # 


mechanical injury. The extensive ravages of the budworm in the 
spruce and a a forests, for example, have resulted in the death of © 
more than 40 per cent of these important pulp-wood species in the | 
areas affected. Trees weakened or killed by this pest quickly show | 
signs of rot. | Oe 
Investigations thus become necessary to determine to what extent 4 
d: cerioration can proceed before the wood loses its economic value 
for pulping. Such investigations are under way at the Forest 
Products Laboratory, and it is hoped that the results will lead to J 
better methods of selecting the wood, to the end that the value of ~ 
partially decayed material will be fully realized. . 
In connection with the control of decay and molding in pulp stored 
commercially, much attention has been devoted to the use of anti- 
septics introduced into the pulp to prevent the development of © 
fungous growth. This was found necessary since no other remedy ~ 
seemed at all feasible. During the progress of the investigation a — 
brief report of the behavior of some of the most effective antiseptics — 
and of the method of their application was distributed to the industry — 
- through the courtesy of the American Paper and Pulp Association. 
As there are many fungi concerned in the deterioration of both — 
pulp wood and stored pulp, it was necessary to determine which of © 
these were the more detrimental. For this reason a large number of — 
fungi were studied individually in pure culture in order to determine ~ 
their action on wood fiber, and the resultant infected pulps were | 
examined both chemically and physically with the same object in — 
view. This investigation will be continued and expanded to include > 
other fungi which produce rots of distinctive types prevalent in pulp- | 
wood species. | roe 


DECAY OF WOOD 


Decay in wood is produced by fungi. These fungi are plants, 
differing from the ordinary green plants merely in their form, lack 
of green coloring matter, and methods of nutrition. Ordinary plants | 
get their nutriment from the soil and air; wood-destroying fungi | 
utilize wood substance for this purpose. ee ei 

Many fungi are wood inhabiting, but not all are wood destroying. — 
In studying the effect of fungi on pulpwood and pulp it is ratyraiey 
to discriminate between two'broad groups of fungi—namely, molds 
and wood destroyers. Molds are abundant on pr particularly 
ground wood, but play so little part in the actual disintegration of — 
wood fiber that their effect on its strength may be ignored. The 
active wood-destroying organisms are for the most part hymeno- 
mycetes, or fungi comparatively high in the scale of development. 
These fungi feed actively on the wood substance. 

In the life cycle of wood-inhabiting fungi two essential stages of 
development are recognized: -(1) The mycelial, or vegetative stage, — 
during which the fine, cotton-like branched threads (the mycelium) 
of the fungus penetrate the wood and also develop on the surface if 
the surrounding air be moist; and (2) the fruiting stage, during which ~ 
spores are produced for the further propagation of the fungus. 

The mycelium (PI. I, fig. 1) is the absorbing system of the fungus, 
and in function is comparable to the root system of ordinary green 
plants. In the case of molds, the mycelium enters chiefly the ducts — 
or medullary rays of the wood, where it feeds on the starches, sugars, — 


Bul. 1298, U. S. Dept. of Agriculture -PLATE | 


Fic. 1—Mycelium of a wood-destroying fungus on ground wood after six months’ storage ina 
mill basement 

Fic. 2—Mycelium of Trametes pini in southern yellow pine. The small black lines are the 
fungous threads. The heavy lines are the walls of the wood fibers. Note the numerous small 
holes where the threads have perforated the walls of the fibers 

Fic. 3.—Spore print of a mushroom, Lepiota naucina, obtained by placing the cap, gills down, 
on a piece of black paper. The spores were cast by the billion. (After Atkinson) 

Fic. 4.—Fruit bodies of Polystictus hirsutus on the end of an aspen pulp log. This fungus is 
limited to hardwoods 

Fic. 5—Fruit bodies of Fomes roseus (the larger) and Polystictus abietinus on the end of spruce 
pulp logs in the pile of three-year wood shown in Pl. VI, fig. 3. These two fungi are the most 
prevalent species on conifers 

Fic. 6.—Fruit bodies of Lenzites sepiaria on spruce pulp logs. This fungus is confined almost 
entirely to conifers and develops readily on the drier exposed timbers 


Bul. 1298, U. S. Dept. of Agriculture PLATE II 


Fic. 1.—Encrusting fruit bodies of Polystictus abietinus on a hemlock pulp log. This fungus is 
very abundant on coniferous wood. ‘The pore surface is violet when fresh 

Fic. 2—Longitudinal section of log shown in fig. 1. Note the minute pockets, primarily in the 
sapwood, which are characteristic marks of this fungus 

Fic. 3.—Fruit bodies of Polyporus adustus on aspen pulp wood. The pore surface is smoky 
brown to smoky black. This fungus attacks hardwood pulp logs, particularly aspen, very 
vigorously. 

Fic. 4.—Rot in log shown in fig. 3 

Fic. 5.—Fruit bodies of Stereum sanguinolentum on spruce pulp log. At the ends of the log 
the fungus also forms small brackets. The spore-bearing surface ‘‘bleeds’’ if scratched when 
fresh. The fungus attacks mainly the sapwood of conifers and is not a severe wood destroyer 

Fic. 6.—Fruit bodies of Stereum purpureum on aspen pulp logs. ‘The spore-bearing surface is 
purplish when fresh. This fungus is particularly prevalent on aspen and apparently produces 
considerable decay. The wood shown had been in the yard less than a year 


CONTROL OF DECAY IN PULP AND PULP WOOD 5 


and other easily digested organic compounds. It may also pass 
through the pits in the walls of the wood fibers, but rarely bores 
| through the solid wood substance. For this reason, molds on timber 
| do not affect its pulping quality. The mycelium of wood destroyers, 
| though often quite similar in appearance to that of molds, can 
| usually be distinguished by its disintegrating action on the wood fiber. 
| (Gee Pl. I, fig. 2.) 

- In order to propagate itself successfully, every fungus must have a 

‘fruiting or spore-bearing stage. The spores of molds are usually 
‘borne directly on somewhat specialized superficial mycelium. The 
‘spores of wood-destroying fungi are, with the exception of secondary 
| ones produced in certain cases, borne on or within definite fruit 
| bodies (conchs, brackets, toadstools, mushrooms, leathery incrusta- 
tions, etc.), whose shape, color, and texture are quite characteristic 
| for the different fungi. (See Pls. I, II, and XVIII.) 
Spores, in function, are entirely comparable to seeds. They are 
‘microscopic in size and extremely light, and appear (PI. I, fig. 3) 
_as a very fine powder, which is very often white, though the color 
varies for different fungi. Frequently the spores from a single 
ruit body will number into the billions, most of them being capable 
of producing a new plant. With so many spores blowing about in 
the air and settling on new timber, it is evident that the chances for 
infection are very great, provided the conditions for germination 
are favorable. The most active period for the casting of spores from 
the fruit bodies is during moist weather, which in turn is most favor- 
able for germination and subsequent infection. 


CONDITIONS NECESSARY FOR GROWTH OF FUNGI 


‘The conditions necessary for the growth of fungi are (1) the presence 
| of an adequate food supply, (2) sufficient moisture, (3) at least a 
small amount of air, and (4) a suitable temperature. 

Food is supplied by the wood tissues, and the more easily these 
‘tissues are attacked the more readily will the wood disintegrate. 
The sapwood of practically all species of American timber is non- 
‘resistant to fungous attack, and the heartwood of most of the prin- 
cipal pulp-wood species is hardly more durable than the sapwood. 

_ Where there is a suitable food supply for the fungi, moisture is, 
_ without doubt, the most important factor in decay. The different 
_fungi, however, appear to vary somewhat as to their water require- 
ments. For infection and the early stages of decay a comparatively 
high moisture content of the wood and the surrounding air is highly 
favorable for all fungi. In discussing the effect of atmospheric 
‘moisture on the germination of spores of Lenzites sepraria on shavings 
of shortleaf pine sapwood, Zeller (28) shows that 85 to 100 per cent 
of them germinate only at the high relative humidities of 98 to 99 
per cent. This writer considers that fiber saturation ? of the wood 
is attained at 95 to 96 per cent relative humidity, and concludes that 
even at this point germination is considerably retarded, and that 
below fiber saturation it falls off with extreme rapidity. A slight 


- 2 Green wood usually contains water within the cell walls and ‘‘free’’ water in the pores. In drying, 
the water in the pores is the first to be evaporated. The fiber saturation point is that point at which no 
Water exists in the pores of the timber, but at which the cell walls are still saturated with moisture. The 
fiber saturation point varies with the species. The ordinary proportion of moisture, based on the dry 
w eight of the wood, at the fiber saturation point isfrom 20 to 30 per cent. 


= ee 1. -_ 


6 ‘BULLETIN 1298, U. 8. DEPARTMENT OF AGRIC vs 7 


film of water on the wood surfaces, he believes, is highly fs favo orable 
to germination. Just what moisture content of wood is most f favor- 
able to decay after infection has once taken place is not known. Nor 
is it known what moisture is necessary for infection of sou 
from an infected stick lying in contact with it, so that the my 
may grow from the one to the other. The study of this phase of tt e 
problem is complicated by the fact that moisture may f a0 3 
added to the wood by direct secretion from the myceli dt 
the breaking down of the wood substance itself, in ee ; sik 
water is one of the products formed. Decay may therefore appear 
in certain cases, to as place somewhat below fiber saturation a4 

A certain amount of air in the wood i is absolutely nece ; for the 
occurrence of decay. The fungi require it in their g 
the wood is saturated, the air in the wood cells is 
and fungous growth and decay are impossible. 

The fungi which decay pulpwood generally grow best « 
atures between 75 and 95° F. All will grow at much 
atures, but much more slowly. The most severe winter ¢ 
do not kill them. They merely cease growing and remain ¢ 
On the other hand, a rise of temperature of but a few nein eae 
the optimum has a greater ae influence on growth ' fan ap 
responding reduction. The conditions of moisture ita’ mpel 
under which fungi thrive are such that in most 
they will find a favorable environment during t 
the year. 

FUNGI THAT DECAY STORED PULP WOOD 


The fungi which have been found causing extensive decay in s 
ulp wood in the regions investigated are: Polystictus iaseolus (PL 
fg. 4); Polystictus versicolor, Polyporus adustus (P\. H, or 
Stereum purpureum (PI. Il, fig. 6); Fomes roseus ue 
Lenzites sepiaria (Pi. I, fig. 6); Polystictus abietinus — 
iar 1 and 2); Stereum sanguinolentum 1. I, fig. 5); and ! 
The first four species mentioned attack hardwoods; 
wt are particularly prevalent on aspen. The other ia 
conifers. her fungi found only occasionally are Fomes pin 
Lenzites trabea, Pretheles heteromorpha, Tr. i, Pleurotus ¢ 
— hyllum commune, Corticium galactinum, Stereum rugo 
yporylon cohaerens. Many others are undoubtedly 
pestis bones in the southern and western regions. In $ 
an evolvens is reported as doing considerable 
producing heart rot in living trees are Fomes roseus, | 
vinnie and rametes pini in conifers, and Pleurotus « 
hardwoods Trametes pint produces the oa red heat, "or 
“ring fede.” a 
STORAGE OF PULP Woop ret Hge 3 om 


CHARACTER OF WOOD AVAILABLE FOR PULPING 


oe te woods used for pulping are: Spruce, 57 per 
hemlock, 14.5 per cent; aspen, 6 per cent; b , 5A per cent; and 
various yellow pines, 5.3 per cent. Other woods used in sm aller 


quantities are jack pine, w ite pine, white fir, pee ge 
beech, birch, cottonwood, gum, maple, and yellow poplar. 


CONTROL OF DECAY IN PULP AND PULP WOOD 7 


On the whole, the species used are not resistant to decay, for 
which reason storage of them is difficult. The fact that a certain 
proportion of the wood reaching the mills is already infected or 
decayed in varying degrees (see Pl. III, fig. 1) makes the storage of 
this material even more difficult than that of the sound, since the 
fungi present at the time of piling will continue to develop rapidly 
under conditions favorable to their growth. 


LENGTH OF STORAGE PERIOD 


Most mills aim to carry only a year’s supply of wood in the yard, 
| but circumstances often render longer storage necessary. Wood 
from 2 to 4 years old was found at several mills and it required no 
‘specialist to see that such long periods of storage were disastrous 
under the conditions of piling that obtained. Pulping and chemical 
tests showed how the wood had deteriorated. Much of the storage 
loss is preventable by the introduction of better methods of piling and 
‘improved sanitation. | 
Pulp wood supplies, especially east of the Mississippi River, each 
year come from increasingly great ‘distances from the mills. In some 
cases they are transported 1,000 miles or more. Much of the supply 
is at present coming from less accessible, often swampy, regions, 
where cutting operations are largely dependent on the condition of 
the terrain—winter being the favorable season for operations. This 
leads to a seasonal concentration in production and a corresponding 
congestion at points of delivery, instead of a regular and dependable 
supply. The growing scarcity of material is also a factor which 
induces many operators to stock heavily in order to insure adequate 
material. | 
The result is very often a heavy influx of timber into yards not 
equipped to handle it to the best advantage, because of limited space 
and insufficient labor. Demurrage charges must be kept down, and 
haste in unloading often leads to improper piling. | 

Changes can be brought about only by the close cooperation of the 
pulp-wood producer, the jobber, and the mill operator and his 
employees. These changes must be based on a thorough knowledge 
of the causes of decay and the conditions that favor it. It must be 
fully recognized that the improvements can be effected only if 
' sufficient money is spent for the necessary facilities and labor, and 
for effective supervision of them. 


HANDLING OF PULP WOOD AT WOODS POINTS 


Care of pulp wood should start at production points. Observation 
shows that a large amount of infection and deterioration occurs 
before the wood reaches its destination. 


TIME OF CUTTING 


_ Winter is the best time to cut, since fungous and insect life is 
largely dormant at this season, and chances of infection are almost 
negligible. Infection by fungi occurs during warm, moist weather— 
particularly in the syals Sob regions, in the summer and fall. In the 
South it may occur at almost any time of the year, but it is especially 
likely to take place during the rainy season. Since infection occurs 


8 BULLETIN 1298, U. S. DEPARTMENT OF AGRICULTURE 


mainly from spores, the most active infection period must coincide 
with the time of most active production of fruit bodies. In the more 
northern regions this occurs during the rainy fall months. In low, 
dense woods it may also occur during the summer. Fruit-body pro- 
duction in the spring months is not so abundant, but at the same — 
time these months are usually so wet that timber can not be season | 


before the active infection period sets in. 


a 
‘oy: 
= ‘ 
* As 


REMOVAL OF BARK a 4 


Wherever feasible, removal of the bark from pulp wood at pro-— 
duction points is strongly recommended. ‘This greatly hastens the 
seasoning and also prevents insect attack. The bark of hemlock is 
sometimes removed for use in tanning. This should be encouraged. — 


METHOD OF PILING 


Timber should never be left lying directly on the ground, for woods — 
soil harbors a great variety of fungi, including many wood destroyers. 
It should be placed on log skids, with the piles separated and prefer- 
ably built lengthwise to the prevailing winds. open place on a > 
well-drained slope should be selected wherever oceieie: ree circu- 
lation of the air is the prime consideration. As timber in the woods 
is much more subject to infection from slash and other rotting débris — 
usually left by the logger, and as even under the best storage condi- 
tions available in the woods it can be better handled at the mill, 
it should be shipped as soon as possible. 


STORING OF PULP WOOD AT THE MILL 
REMOVAL OF BARK 


If bark is not removed in the woods it is desirable, wherever feasi- 
ble, that it be taken off at the mill before piling. Barked wood dries 
more rapidly and is less susceptible to insect and fungous attack than — 
wood with the bark on. There is a market for hemlock bark, and 
its sale may offset the cost of removal. | 


SEPARATION OF WGOD 


Separation of highly perishable species, such as poplar, balsam, 
and, white fir, from the more durable woods may be considered desir- 
able by some operators. In deciding this point, however, it should be 
kept clearly in mind that improved storage conditions will go far 
toward eliminating deterioration in mixed piles. The cost of sepa- 
ration will necessarily be considerable, and this item must, of course, 
be warranted by the returns. 

Separation of badly infected shipments (Pl. ITI, fig. 3) from sound 
wood is strongly recommended. Although it is not economically 
feasible to pick out all rotten sticks from shipments of otherwise 
sound material, something can be done at times in this direction by 
a diligent yard crew. Badly infected shipments should always be — 
segregated in an allotted portion of the yard for quick utilization. — 
This precaution is important. Deterioration in such wood vs propor- 
tionately much greater than in sound or slightly infected stock. If rts — 
intermixed with sound wood it serves as a rapid and vigorous source of — 
infection to the better material. 


Bul. 1298, U. S. Dept. of Agriculture PLATE III 


ow 


. 
7 


Fic. 1—Heart-rotted hemlock as delivered to a mill. The largest log is about 3 feet in 
diameter with a shell of sound wood not exceeding 6 inches in thickness. A large propor- 
tion of hemlock is defective from heart rot 

Fic. 2—Bark and insect borings near the base of close-ranked piles of mixed spruce and 
balsam. Such débris hinders the seasoning process 

Fic. 3.—Mixed spruce and tamarack pulp logs seen after they were received at amill. Note 
the excessive amount ofsaprot. These logs may have been rotten fallen material salvaged 
from the woods, or the decay may have developed during too long storage previous to 
delivery. Such wood should never be mixed with sound wood during storage 

Fig. 4.—Eight-foot spruce stored intheriver. Logs which are not kept saturated will decay 


Bul. 1298, U. S. Dept. of Agriculture PLATE IV 


tions for decay 
Fic. 2.—Partial view of conveyor in use for 2-foot wood 
Fic. 3.—Pile of 2-foot rossed spruce about 40 feet high and containing about 10,000 cords. The 


{ 
Fic. 1.—Spruce pulp wood unloaded indiscriminately into river, offering very favorable condi- 
tricked wood in the foreground was so placed for the purpose of establishing a fire lane , 


Bul. 1298, U. S. Dept. of Agriculture PLATE V 


Fic. 1—Ranked piles of 8-foot spruce. This type of massed piling, without adequate ven- 
tilation at the sides and beneath the ranks, leads to serious decay in a comparatively short 
time 

Fic. 2.—Piles 35 feet high of 8-foot jack pine and spruce. Note the orderly arrangement and 
clean yard, conditions which are all too rare in the pulp industry 

Fic. 3— Bark and fragments of rotten wood which have been shaken down from the conveyor. 
Such detritus readily absorbs and holds moisture from rains and, in the case of any but 
water-soaked wood, promotes decay: 

Fic. 4.—Bark and rotten wood at the base of a pile of 2-foot spruce and balsam stored for about 
one and one-half years. New rossed wood has been piled on this old, thoroughly infected 
‘base. Considerable loss from decay in the new wood may be expected from this source. 
Before starting new piles the old wood should be utilized and the surface of the ground cleared 
of all infecting material 


Bul. 1298, U. S. Dept. of Agriculture PLATE VI 


£ 


Fic. 1—Representative samples of infected spruce and balsam taken from the base of the pile 
shown in PI. V, fig.4. These are badly decayed and will be almost worthless when utilized 
Fic. 2.—Pile of pulp wood equipped with spray nozzles spaced 30 feet apart each way and 
delivering 2 quarts of water per minute. The nozzles should be higher, about 5 to 10 feet 
above the wood, in order to cover the pile. For the most efficient results and the best dis- 
tribution of moisture, spray heads should be selected which break the water into the finest 

possible spray. (After Hoxie) 

Fic. 3.—Piles of 8-foot spruce and balsam up to 35 feet in height placed directly on the ground 
and closely massed. This wood was found very severely decayed after three years’ storage 
Fic. 4——Ranked piles of 8-foot tamarack, about 35 feet high, separated by a space of about 
2 feet at the base, which permits considerable air circulation. Higher foundations would 

be advantageous 


q 


CONTROL OF DECAY IN PULP AND PULP WOOD 9 


METHODS OF STORAGE 


At the mill puJp wood is stored in the open in three ways: (1) In 
the water (Pl. IIT, fig. 4 and Pl. IV, fig. 1); 6) in conical piles of 2-foot 
wood built by means of conveyors (PI. IV, figs. 2 an 3); and (3) 
ete ricked in long piles (Pl. V, figs. 1 and 2) up to 30 or 35 feet 

Dadiiste immersion in water is theoretically ideal storage, because 
wood in a saturated condition can not rot. In present commercial 
practice, however, complete immersion is not practicable. Most of 
the logs float, and often the exposed portion dries out sufficiently for 
decay to take place. Some logs are left on the river banks at low 
water; others, as they are unloaded from cars into the river, are left 
in a high pile extending out into the water. Under such conditions 
of exposure, wood is very liable to decay, particularly in a zone just 
above the water line. 

In view of the difficulty of keeping the wood saturated, it is be- 
lieved that storing the logs on well-drained land is preferable to 
holding them in the river, provided they are properly piled. 

Of the two methods of piling pulp wood, ricking seems preferable 
to piling in large conical piles, provided the ricked piles are off the 

ound and, especially in the case of the smaller woods and shorter 
eneths, separated laterally one from another so as to allow con- 
tinuous circulation of air. With hemlock, however, when stored 
green with the bark on, piling in close ricks may result in less decay 
than when the ranks are separated. ‘The conical pile offers the ad- 
vantage of requiring less space and trackage, but it has drawbacks 
from a pathological standpoint which, in many cases, can not be 
eliminated. Its volume is so great that drying takes place only in 
the outer part, and deterioration is apt to be rapid wither Drying 
is further retarded by the infiltration of bark débris, which rattles 
down from the conveyor (PI. V, fig. 3) or is broken loose from rough 
wood in dropping. This débris is usually allowed to accumulate 
(Pl. V, fig. 4), and in time forms an excellent bed in which fungi 
(Pi. VI, Fe. 1) can readily develop. Conical piles are placed di- 
rectly on the ground, which is usually moist and thoroughly per- 
meated with wood-destroying fungi, with the result that direct in- 
fection from the soil occurs. Because drying moist wood in large 
piles such as these is out of the question, the only alternative is to 
apply water in the form of a fine spray in an effort to keep the wood 
too wet for decay. Such a procedure, however, can be recommended 
only when the wood has a high water content at the time of piling. 

Hoxie (10, 11, 12) has discussed the relation of moisture to decay 
and has advocated the use of the spray method (PI. VI, fig. 2) both 
as a preventive of decay and as a precaution against fire. As regards 
moisture in the wood as stored, his observations are: 


The character of pulp wood with respect to moisture content varies widely at 


different mills. Wood which is river driven and is piled out wet after remaining 


in water for several months contains about 55 per cent moisture, and tests made 


- on chips from this wood after remaining in the pile for one season indicate an 


average moisture content of from 45 to 50 per cent, which, from best informa- 


tion obtainable, is never below 40 per cent. On the other hand, wood delivered 


by rail at some mills shows a moisture content as low as 23 per cent. 


In the present investigation, moisture determinations were made 
on a large number of wood samples, both sound and infected, which 


. £0 BULLETIN 1298, U. S. DEPARTMENT OF AGRICULTURE 2% 
had been stored in ranked piles. No data were obtained on fresh 
river wood; but wet spruce and balsam, after storage in close-ranked _ 
piles at one mill for about a year, showed a maximum of 44.4 per © 
cent and an average of 38 per cent. In one instance rotten 3-year- 
old samples taken from near the bottom of a large storage pile of 
solidly massed ranks of rail-shipped spruce inGwed a moisture con- 
tent of from 33 to 35 per cent, which is practically the same as for 
green spruce. The top of a similar 35-foot pile ran about 27 per | 
cent. Rotten spruce from another mill, probably stored for about — 
the same length of time but in a much lower pile, was reduced to ~ 
about 18 per cent. Green wood just off the cars contained about — 
40 per cent moisture. Cs 
he fact that spruce and balsam will rot rapidly in an essentially — 
green condition argues against their storage in large conical piles, 
unless continuously water-soaked. Hoxie believes that wood with 
less than 40 per cent moisture is best stored in ranked piles. Snell — 
(25) concludes from experiments with five fungi on spruce that 
decay is greatest at a moisture content of between 30 and 57 per 
cent, but that 60 per cent of water will eliminate all danger of serious 
loss from decay. | ‘e 
Present knowledge of the actual amounts of moisture which will — 
preserve timber is based on observation, or unscientific experimenta- — 
tion. More careful investigations will undoubtedly reveal differ- 
ences in the reactions of the various wood-rotting organisms toward — 
water. Actual mill tests are highly desirable. It is well established 
that spruce and balsam containing 35 per cent moisture will decay 
readily. The few other records available indicate that in certain ~ 
species considerable decay may also occur up to 80 or 90 per cent ~ 
mene content. Above this point the rate of decay may fi much — 
reduced. ht | 
Wood which reaches the mill in a partially dried condition is 
probably best stored in ranked piles so that drying may progress to 
a point where decay is markedly retarded or entirely inhibited. 
Precautions must be taken to get ample ventilation around and 
beneath the piles. Under present practices the ranks are often 
solidly massed without any possibility of air seasoning. (See Pl. VI, | 
fig. 3.) Such a condition should be corrected by separating the 
ranks by a space of from 4 to 6 feet (Pl. VI, fig. 4) and running them ~ 
in the direction of the prevailing winds. If thay can be placed ona 
hillside in the direction of the slope,so much the better, as thiswillallow 
improved air drainage. Cross ventilation, accomplished largely by 
free air circulation through the foundations, ahold be pelvis for, 
as this assists in the removal of the humid air near the ground level 
and hastens seasoning in the bottom of the piles. = : A 
Ranked piles are sometimes placed directly on the ground (Pl. VII, _ 
fig.1). In one case they were even piled in a drainage canal (PI. VII, 
fig. 2). More often they are placed on parallel rows of poles or logs. i 
The skid logs are commonly taken from the pulp-wood shipments as 
needed and kept in use as long as they are serviceable, frequently until — 
they are in advanced stages of decay. On moist land they are often 
forced into the ground so far that sufficient air can not circulate 
underneath the piles. (See Pl. VII, fig. 3.) Inasmuch as rotten 
foundations will transmit infection to the wood piled on them, if pulp 
logs are to be used for foundations it is much better to use fresh logs 


ie. 


d 
; 
. 


CONTROL OF DECAY IN PULP AND PULP WOOD 1l 


for each new pile, removing the old ones and utilizing them for pulp, 
if suitable. Before new piles are started it is also good practice to 
— up and remove all bark débris which has accumulated from the 
old ones. 

A better type of foundation can be made by supporting creosoted 
stringers on concrete piers or creosoted wood blocks, with the footings 
sufficiently large to prevent them from being forced into the ground. 
The supports bank be at least 12 inches high to allow ample side 
ventilation. A concrete foundation experimented with at one of the 
Wisconsin mills is similar to a rail in section and 10 feet long. The 
base is 18 inches broad, and the web is proton with 5-inch circular 
se spaced 12 inches apart. (See fig. 1.) This has been found 
of sufficient strength to stand up under the hardest usage it is likely 
to get with large 12 to 16 foot hemlock logs. (See Pl. VII, fig. 4.) 


ROTATION OF WOOD 


None of the wood should be held in storage longer than absolutely 
necessary, for losses during the second and third years are entirely out 
of proportion to those of the first year. No method of storage which 


Two rods I” from center line. 


10° aes 
9-holes 5"dia. I2”o.c. 12° r 


734. rods 10’ long. Six rods 3”o.c. 


Fic. 1.—Sketch and specifications for precast TP eae skid in experimental use at a Wisconsin 
m 


is economically feasible will fully protect wood for long periods, and 
mills should make every effort to reduce the storage time to a mini- 
mum. ‘The time in storage should be reckoned from the date of 


cutting and due allowance made accordingly in assigning a rotation 


number, which should be plainly marked on each pile (Pl. VIII, fig. 1) 
or section of a pile in the yard. ‘The material should always be sent 
to the wood room in the order indicated. Large conical piles should 
be completely utilized. New wood should never be piled on old wood 
at the base. Thesame attention should be paid to cleaning up bark 
débris at the bottom of these piles as would i given to ranked piles. 

In order that the wood may be piled most conveniently for later 
utilization, a survey of the yard is ene! desirable. Following this, 
a diagram and blue prints can be prepared for the use of the yard 
crew, so that a definitely prearranged plan will be available to coun- 
teract a tendency toward indiscriminate piling. 


GENERAL SANITATION 


Many yards are littered with rotten or infected wood or bark débris 
which should be removed and burned. Infection of new wood may 
spread from this in two ways, namely, by spores from fruit bodies 


12 BULLETIN 1298, U. S. DEPARTMENT OF AGRICULTURE 


developing on it and by direct contact which permits the mycelium _ 
to grow from one stick to another. Bark débris (Pl. VIII, Fig. 2) 
ail frapinderl és of rotten wood on the ground form an excellent bed ~ 
for the growth of fungi, since the mass is usually in a moist condition. — 

The wood which is in too bad condition for pulp should be burned, | 
and noticeably infected wood which is still usable should be segre- 
gated and utilized as soon as possible and not mixed in piles with 
with sound material. 

In order to insure better surface drainage (Pl. VIII, fig. 3) and 

reater cleanliness, it is advisable to surface yards with cin 

(Pl. VIII, fig. 4) to a depth of 4 to 6 inches. Incidentally, this will 
keep down the grass and weeds which impede air circulation around 
the base of piles. . Te 

At most mills the cleaning-up program must be carried out grad- 
ually as opportunity permits. here débris has been accumulatin 
for a number of years the task will call for concerted and specia 
effort. In some cases it may even prove advisable to change the 
location of the yard rather than attempt to put it in satisfactory 
condition. This would apply particularly to low yards where large 
amounts of filling are required 

Every yard should be sufficiently drained to insure immediate 
run-off after rains. Earth is much better for filling than barker 
waste or other woody débris, which if not kept saturated with ground 
water will soon rot and furnish an uneven and unstable foundation 
for the piles. In any case the yard should be heavily cindered. : 

One Wikcohain mill employs a clean-up crew to look after the 
general sanitary condition of the yard. At least one or two men are 
continually at work digging out weeds and grass (Pl. VIII, fig. 4), 
raking up bark débris, ete. The wood yard at this mill is well drained 
and is surfaced with cinders, and there is no appreciable loss from de- 
cay during the storage periog which is usually not longer than two 


years. This condition shows quite conclusively the advantages to be ~ 


derived from a good location and attention to sanitary details. 
Spraying the ground beneath piles with a ‘‘weak tannic acid 
solution” (19) or any other antiseptic, is not recommended. ‘Tannic 
acid is not an effective fungicide, and treatment with an effective 
antiseptic is too expensive in proportion to the benefits derived. | 


SUMMARY OF RECOMMENDATIONS 


It is believed that if the recommendations just given are consist- 
ently followed, losses in stored wood can be for the most part pre- 
vented. The big outstanding fact is that present conditions, wherever 
they favor fungous attack, must be corrected before mills can hope 
to eliminate deterioration from these causes. The extent of loss 
in the wood yard has never been fully realized. All other operations ~ 
about the mill are closely scrutinized, and are corrected wherever 
losses are exposed. Why except the wood yard? It may require 
expert assistance to get the best results, but once the system gets 
under way it becomes largely a question of close attention to detail. — 
Money will have to be spent, just as it must be spent in the replace- 
ment of old machines with more modern ones in order to meet close 
industrial competition. Taking as a very conservative estimate a 
shrinkage in value of $1 to $1.50 per cord for wood cut one and one- 


4 
; 


Bul. 1298, U. S. Dept. of Agriculture PLATE VII 


Fic. 1—Four-foot hemlock piled directly on the ground and with no spacing between the 
ranks. Wood should never be placed directly on the ground. Even if these ranks had 
been separated, the pile in the background running at right angles to them would have cut 
off most of the air circulation 

Fic. 2—Hemlock pulp logs 12 to 14 feet long piled in a drainage canal 12 feet deep. The logs 
which are not wholly submerged will decay with extreme rapidity, owing to the moisture 
conditions being favorable to decay and the impossibility of further drying 

Fic. 3—Hemlock logs used as foundations for 12 to 14 foot pulp wood. The accumulation of 
bark from the handling and peeling of logs is nearly at the top of the rotten foundations, so 
aoe ite. peor might about as well be piled on the ground. ‘The whole mass is an excellent 

ungus be 

Fic. 4— Concrete skid, built according to the sketch shown in fig. 1 (p. 11), in experimental 
use at a mill 


Bul. 1298, U. S. Dept. of Agriculture PLATE VIII 


Fic. 1—Pulp wood piles marked with date of arrival at the mill, to be used in rotation 

Fic. 2—Bark accumulation resulting from the hand peeling of hardwoods, a source of infection 
to wood piled on it. It was several feet thick over the entire yard 

Fic. 3—A storage yard on swampy ground. Pulp and pulp wood can not be stored under 
such conditions without heavy loss. Certain portions of the yard were being raised several 
feet with barker waste, surfaced with cinders. Earth and cinders would serve the purpose 
much better 

Fic. 4— Wood yard surfaced with cinders and located on a well-drained slope. The company 
recognizes the value of cleanliness and employs a crew to rake up and remove all accumulated 
bark endrotten wood. Workman ‘‘spudding”’ out grass and weeds and leveling the cinders. 
Wood is not usually stored longer than a year, and there is no appreciable loss from decay 


CONTROL OF DECAY IN PULP AND PULP Woop 13 


half to two years, the losses for an average mill will be a very con- 
siderable item. As these can largely be prevented through the 
improvement of storage conditions, at least part of the money repre- 
sented in losses might well be invested for their prevention. 

The points to be emphasized in handling pulp wood are: 

1. Timber should be left in the woods the shortest possible time, 
and while it is there it should be stored on skids, on a well-drained 
site fully exposed to the wind, in separate piles running, preferably, 
in the direction of the prevailing winds. 

2. If borers are troublesome, soaking in water and peeling are 
effective. 

3. Logs should, if possible, be peeled, in order to hasten air drying 
and also to prevent borers from attacking the wood. 

4. Badly infected shipments or portions of shipments should be 
separated from sound wood and segregated for rapid utilization. 
5. Wood should be stored at the mill on well-drained land. The 
_ site should have a cindered surface which will give rapid run-off and 
keep down weeds which hinder air circulation around the base of piles. 
Barker waste is a poor fillmg material, because it harbors fungi and 
forms a very unstable foundation for piles, even when surfaced with 
cinders. 

6. Conical piling by the use of conveyors is not considered as good 
as ricking for partially dried wood. For river wood it seems satis- 
_ factory, when the piles are equipped with an overhead spray system 
to keep the surface moist. The method needs testing under commer- 
cial conditions, however, in order to determine more exactly the per- 
centage of moisture in the wood necessary for protection. The 
_ sprays are also valuable features for fire prevention. 

7. Wood should never be ricked directly on the ground. The best 
procedure is to use reinforced concrete skids provided with sufficient 
openings to insure good cross-ventilation or concrete piers supporting 
_ stringers which have been given a pressure treatment of coal-tar 
creosote. If treated properly, either of these types should last 20 to 
25 years. The latter is preferred because it gives better cross- 
ventilation. If it is not considered feasible to equip the yard with 
conerete piers, the next best method would be to use wood blocking, 
pressure-treated with coal-tar creosote, as supports for the stringers. 
The stringers should, in any case, be at least 12 inches, preferably 18 
inches, off the ground. If pulp logs are used they should be of the 
larger sizes win should be pulped or removed when the piles are 
_ torn down. 

8. High-ranked pe should, as a rule, be separated by open spaces 
4 to 6 feet wide and with their length in the direction of the prevailing 
winds. Between low piles a 3 to 4 foot space should be sufficient. 

9. Each pile should be marked with the date on which it was piled, 
or if possible with the date of cutting. The piles should be used in 
the order they were cut. 

10. All decayed and unserviceable wood should be removed from 
_ the yard, and after the removal of a pile of wood the bark should be 

cleaned up. | 


14 BULLETIN 1298, U. S. DEPARTMENT OF AGRICULTURE 
PULPING CHARACTERISTICS OF DECAYED WOOD 


PHYSICAL PROPERTIES OF MECHANICAL PULP MADE FROM SOUND 5 
AND DECAYED SPRUCE Ri 


CHARACTER OF WOOD USED 


In order to demonstrate the large losses sustained and the difficul- — 
ties encountered in the use of decayed wood, comparative grinder — 
runs were made on sound and on decayed spruce wood at one of the 
cooperating mills. 

he sound wood, sample 1 (Pl. IX, fig. 1), was 12-foot Wisconsin 
— taken direct from a car which had just been received at the 
mill. 

The decayed wood, sample 2546 (Pl. IX, fig. 2), represented 
ordinary mill-run Minnesota spruce, approximately 3 years old. It | 
had been stored in 8-foot lengths directly on the ground, in close ’ 
ricks, in a solid mass of several thousand cords. (See Pl. VI, fig. 3.) 
The logs used for the grinder runs were selected from the lower half 
of the piles. They were representative of severely infected material, 
_ ee was so badly decayed that it would have been rejected by 
the mill. 

The principal fungi rotting the wood, in the order of their frequency, 
were Homes roseus, Stereum sanguinolentum, Polystictus abietinus, 
Lenzites sepiaria, and Trametes pini. <A tally of 184 of the 250 sticks 
showed 75 sticks infected with the first fungus, 59 with the second, 
28 with the third, 16 with the fourth, and 6 with the fifth. Fomes 
roseus was represented in the living tree to a certain extent as a heart- 
rotting organism, but most of the rot probably developed in the pile. 
Trametes pint was undoubtedly introduced altogether as heart rot from 
the standing tree. All the other fungi developed from infections sub- 
sequent to cutting. Of these, Lenzites sepiaria readily attacks both 
heartwood and sapwood; Stereum sanguinolentum and Polystictus 
abietinus attack the sapwood principally. 3 


METHOD OF PREPARATION 


Approximately 5 cords each of infected and sound wood were 
selected, weighed, and ricked. This material was then sampled py ‘ 
cutting disks 6 inches thick for specific gravity determinations (Pl. — 
IX, fig. 3) and thinner disks for moisture determinations. The — 
moisture disks were ae directly after cutting, wrapped in paper _ 
to prevent loss of small particles of bark and wood, and sent by — 
express to the laboratory for the actual moisture determination. 
Fourteen of the sound and 26 of the infected sticks were sampled in 
this manner. atk 0 

After being sampled the logs were dumped into the hot pond and 
cut into 2-foot bolts, all the odds and ends being collected and ~ 
weighed and this weight deducted from the weight of the rough wood. 
The 2-foot bolts were barked on knife barkers and corded in cord 
ricks. icc 

Preliminary to grinding, the ground-wood chest was run dry and 
washed out. Two 3-pocket grinders were used, with a pressure of 35 
pounds per square inch on the piston heads and an average speed of 
220 revolutions per minute. The stones were sharpened equally for 


CONTROL OF DECAY IN PULP AND PULP WOOD 15 


both runs. The temperature of grinding varied between 120 and 
180° F. (49 to 82° C.). After the separated screenings were weighed 
the pulp was run over the wet machine and the dry weight. calculated. 

The essential data obtained from these tests are shown in Table 1. 


TasBuE 1.—Data on the grinding of sound and decayed spruce 


Sound Decayed 
wood, wood, 
sample 1 |sample 2546 


SP SEAS 85 Baie IG) MR St BRE Pe Se cana pieces__ 1140 2250 


Mpematn CUR WOOGS 20 Seo eS SEE) eee pounds_-_ 17, 920 18, 839 
Weienrotrouen wood, Oven-dry *..2.-_-.-.-.0--2------2L 22st ---22--e dois 10, 720 12, 600 
Loss in barking, based on oven-dry wood-.--.-.----------------------- per cent__ 32.4 31.3 
Weimntorparked wood, oven-dry =~ 22 2.-22 20-222 t ease n ie le pounds-_- 7, 250 8, 650 
Wilelaonpmlnoven-drvi weight. . 2224. -loc et lee sl eee ed dor ssi 6, 826 6, 783 
Yield of oven-dry pulp, based on oven-dry barked wood-------------- per cent__ 94. 2 78. 4 
Yield of oven-dry pulp, based on oven-dry rough wood___-__-------------- G0! = 63. 7 53. 8 
1 12-foot lengths. 28-foot lengths. 3 Computed from moisture samples. 


YIELD AND QUALITY OF PULP 


The results of this particular trial indicate a yield of 94.2 per cent 
in the case of the sound and of 78.4 per cent in the case of the decayed 
wood, on the basis of oven-dry weights in each case. Decay thus 
accounts for a loss of 15.8 per cent. . 

A sample of the pulp from each grinder run was shipped to the 
Forest Products falteainey: for physical and microscopic examina- 
tion and for paper-making trials. Samples were also placed in moist 
storage for further observation, as described later. 

Sedimentation tests indicated that the pulp made from decayed 
wood was slightly freer than that made from sound wood, although 
the difference was not marked. Microscopic examination of the 
average length of fiber particles showed 1.57 millimeters for the 
sound in comparison with 1.27 millimeters for the decayed material. 
The decayed pulp contained about twice as much débris, in the form 
of very small particles evidently produced by pulverizing the infected 
wood in the grinding. A large percentage of this débris would, of 
course, be lost during conversion on the paper machine, so that white 
water losses from decayed pulp should be larger than for sound pulp. 
‘The stock was run into 100 per cent ground-wood sheets without 
_the use of size, alum, or color. Physical tests on the papers, as 
shown in Table 2, indicate that both stocks, in so far as these runs 
would show, were of about the same strength. The pulp made from 
decayed wood, however, contained the larger number of shives and 
was decidedly the darker of the two in color. 


TaBLE 2.—Data on waterleaf papers made from sound and from decayed 
spruce woods 


Weight | Points 


of ream, per Average 


Average |Tempera-| Humid- 


Sample |. +4: F 
No. Description 24 by pound hae a stretch ture ity 
36—500 | per ream g 
Pounds Meters | Per cent 9. Fy Per cent 
1AA_-_| From sound wood, No. 1. -__---- 47 0. 304 2, 760 1.4 87 64. 5 


2AB- --| From decayed wood, No. 2546. -- 48 . 304 2, 610 163 85 64. 0 


16 BULLETIN 1298, U. S. DEPARTMENT OF AGRICULTURE a 


PHYSICAL PROPERTIES OF SULPHITE AND SODA PULPS MADE FROM . 
SOUND AND FROM DECAYED WOOD ‘i . 


CHARACTER OF WOOD USED 


Investigations were made at the Forest Products Laboratory to 
determine the effect of decay in wood on the yield and on the quality 
of chemical pulps made from it, and to ascertain the difficulties en- 
countered in manufacturing paper from such pulps. 

Through the courtesy of the cooperating mills, shipments of spruce, 
hemlock, and aspen woods representing sound wood and wood in 
various stages of decay were received. These woods may be de- 
scribed as follows: 


Sample 2545. Spruce wood from a Wisconsin mill; nearly free from decay; 
taken from the top of a pile approximately 35 feet high, containing about 10,000 
cords of 8-foot wood. Used for sulphite cook No. 7, pulp designated as No. 2547. 

Sample 2546. Spruce wood; considerably decayed; taken from the bottom of 
the same pile from which No. 2545 was taken. Used for sulphite cook No. 6, 
pulp designated as No. 2548. 

Sample 2560. Spruce wood from a Wisconsin mill; nearly free from decay and 
in physical appearance similar to No. 2545. Used for sulphite cooks Nos. 8 and 
10, pulp designated 560A and 560, respectively, and for soda cook No. 6, pulp 
designated as No. 2559. 

Sample 2541. Spruce wood froma Wisconsin mill; so badly decayed that it 
was rejected at the pulp mill. (See Pl. IX, fig. 4.) Used for sulphite cook No. 9, 
pulp designated as No. 2555, and for soda cook No. 7, pulp designated as No. 
2557. 


Spruce wood, not numbered; presumably sound; received at the Forest 
Products Laboratory and cooked prior to these studies. Used for sulphite cook 
No. 336, pulp designated as No. 2540. ‘¥ 

Spruce wood, not numbered; presumably sound; received at the Forest 
Products Laboratory prior to these studies. Used for soda cook No. 109, pulp 
designated as No. 540. . 

Sample 2552. Aspen wood selected at random from a Michigan mill pile; 
extent of decay not certain. Used for sulphite cook No. 1, pulp designated No. 
5521, and for soda cook No. 4, pulp designated as No. 552D. 

Aspen wood, not numbered; presumably sound; received at the Forest Prod- 
ucts Laboratory and cooked prior to these studies. Used for sulphite cook No. 
351, pulp designated as No. 50. am 

Sample 2542. Hemlock wood from a Wisconsin mill; considerably decayed; 
used for sulphite cooks Nos. 2, 3, and 5, pulps designated respectively 542A, 542B, 
and 542C, and for soda cook No. 8, pulp designated as 542D. 

Sample 2554. Hemlock wood from the same mill from which No. 2542 was 
received; sound; used for sulphite cook No. 4, pulp designated as No. 554. 

Hemlock wood, not numbered; presumably sound; received at the Forest 
Products Laboratory and cooked prior to these studies. Used for soda cook 
No. 228, pulp designated as No. 40. 


CHIPPING LOSSES 


On account of the breaking down of the fibers by the fungi, decayed 
wood is brash. In the chipping of such wood a considerable loss 
occurs in ‘“‘sawdust” and shives which are rejected by the screens. 
Trial chipping and screening of sound and decayed spruce wood from | 
the lot under investigation gave the following screening losses in 
per cent by weight: 


Per cent loss 
Sound. . fo 3 ee a 4,4 
Relatively sound |(No. 2545) _--.. _-._=_ 4222 ohee ee 5. 6 
Samewhat decayed. (No. 2560)... 2. _ 4-2 13. 2 
Considerably decayed (No,,2546). 0° ""* Ve 15, 


Badly deeayed (No, 2541) 2. - .- i. ._. Se 17. 0 


— 


Bul. 1298, U. S. Dept. of Agriculture PLATE IX 


Fic. 1—Fresh sound spruce used for experimental grinding in comparison with the infected 
wood shown in fig. 2 

Fic. 2.—Rick of infected spruce wood used for experimental grinding. This was representative 
of the material toward the base of the pile shown in PI. VI, fig. 3 

Fic. 3.—Specific gravity disks cut from the infected spruce shown in fig. 2. Sample 23 was 
decayed by Lenzites sepiaria and Polystictus abietinus, sample 21 by Stereum sanguinolentum, 
and sample 19 by a fungus which was not fruiting and hence indeterminable 

Fic. 4— Spruce wood about four years old sent to the laboratory for sulphite and soda cooking 
tests. This wood was rotted mainly by Fomes roseus and was too far gone for commercial 
use 


Bul. 1298, U. S. Dept. of Agriculture PLATE X 


Fic. 1—New ground-wood pulp placed directly on ground. A concrete base would prevent 
all infection from the ground upward into the base of the pile 

Fic. 2.—Rotten platform recently used for ground wood. It rests directly upon moist soil, 
from which it became infected. If plank foundations are to be used, all decaying material 
should first be removed from the site, the ground surfaced with cinders, and fresh new timber 
used for each pile. In the long run a concrete base will be found much better and cheaper 

Fic. 3.—Base of a pile of hydraulic-pressed ground-wood pulp stored two years in an open 
shed. The light area to the right is a very rotten spot in the floor, from which the piece of 
pulp to the left has been turned back. The indication is clear that this particular decayed 
area in the pulp originated from the floor 

Fic. 4—New ground-wood pulp stored on arotten base consisting of hydraulic-pressed ground- 
wood pulp two years old. The floor is also completely decayed. Under no circumstances 
should clean pulp be placed in contact with decayed or infected material 


~ CONTROL OF DECAY IN PULP AND PULP WOOD Daf 


Even though the yp saan used in this instance is not comparable 
- with mill equipment, the results show the relative effect of decay 
upon this type of loss. 


PREPARATION OF SULPHITE PULP 


Both sound and decayed spruce, hemlock, and aspen were cooked 
___ by the sulphite process in the laboratory digester, under conditions as 
nearly uniform as possible. In Table 3 are indicated the conditions 
- of cooking and the respective yields. The data on cooks Nos. 351 
- and 336, of sound aspen and sound spruce, respectively, were taken 
from the laboratory records of previous tests and were used for 
purposes of comparison. 


TABLE 3.—Sulphite cooks of sound and decayed woods 


[Yield percentages are based on oven-dry weights of wood and pulp] 


Yield} Yield | Yield ier 
‘ ‘ i ie ie 5 p.ct. 
_ Sample] Cook} Pulp Tgscrition ape Max.|Total | Free oe of of of avail- 
No. | No. | No. Pp agit temp.| SO2/SOa SO crude] screen- |screened| able 
2/pulp| ings | pulp ae 
ine 


Hoursi 3 Geil Peet. | Ps cb.) Poct.ePs ct) Po cbc PR.ct: 1h oP sets 
0. 46 14 


See 336 | 2540 | Spruce, sound____- 8. 25 153 | 5.86 | 4.56 | 1.30 | 47.1 4 and 
2545 7 | 2547 | Spruce, decayed___| 8 152 | 5.34 | 4.10 | 1.24 | 44.6 .8 43. 8 14 
2560 8.) 560A).____ (Ce oo 8 155 | 5..50.| 4.37 | 1.13 |, 47. 4 .6 46.8 16 
2560 Pi oo j- (Oi aiectad belaioepet 8 153°}, 5.50 | 4.35 ) 1. 15 | 45. 9 .8 45. 1 16 
2546 6 | 2548 |_.__- AC eer ee od a Be 8 152 | 5.45 | 4.28 | 1.17 | 43.9 .4 43.5 14 
2541 9 | 2555 |_...- ‘h(t oar eae 8 153 | 5.56 | 4.45 | 1.11 | 39.6 1.2 38. 4 20 
2554 4 54 | Hemlock, sound___| 8 153 | 5.38 | 4.36 | 1.02 | 46.6 *8 46. 1 36 
2542 2| 542A) Hemlock, decayed_| 8 152 | 5.44 | 4.33 | 1.11 | 44.9 eh 44, 2 26 
2542 3} 542B/____- eae sak, 8 153 | 4.92 | 3.83 | 1.09 | 46.6 .8 45. 8 35 
2542 5 | 642c/____- (UG. FER de eee y 8 153 | 5.36 | 4 27 | 1.09 | 46.8 oh 46. 1 44 
peer ees 351 50 | Aspen, sound__-__-} 8.25 | 152] 5.50] 4.20 | 1.30] 47.5 Sli 47.4 12 
2552 1 | 5521 | Aspen, decayed__-_| 7 153 | 4.28 | 3.14] 1.14 | 42.1 .0 42.1 19 


PREPARATION OF SODA PULP 


Soda cooks were made only on decayed specimens of the three woods. 
The cooking conditions were maintained as nearly uniform as possible 
except in the case of the aspen, for which a larger amount of chemical 
was used. In Table 4 are given the cooking data. The data shown 
for cooks Nos. 109 and 228, on sound spruce and sound hemlock, re- 
spectively were taken from the laboratory records for purposes of 
comparison. 

: YIELD OF PULP 


_. The yield of screened sulphite pulp obtained from the decayed 
spruce woods did not vary greatly from each other, except in one case, 
nor were they much lower than the yield from sound spruce. The 
exceptional yield, which was abnormally low, was that from the re- 
_ jected wood, No. 2541. None of the hemlock woods was sufficiently 
_ decayed to show a pronounced decrease in yield. The aspen pulps 
showed a lesser yield with greater amount of decay. 


§23°—25t—_—2 


18 BULLETIN 1298, U. S. DEPARTMENT OF AGRICULTURE 


TaBLEe 4.—Soda cooks of sound and decayed woods 


[Yield percentages are based on oven-dry weights of wood and pulp] 


Maxi-| Lime NaOH | Liquor 


i at | Total! per 100 | per 100 -| Yield| Yield | ~-. 
py Cook] Pulp | neseription hee maxi-| time | pounds | pounds ser of of | Yield - 
Ko. | No. | No. pres- um} of | oven- | oven- |W y¢q|crude|screen- rai 

sure | Pres- cook} dry dry ulp | ings : 
sure chips | chips 


| | | | | 


Lbs. | Ars. | Hrs. | Pownds|Gallons | P. ct. | P. ct.) P. ct.) P. ct. 
t 20.3 27.4 75.9 | 


a 109 | 540 | Soundspruce._| 100 a| 2k 9 | 50.2 4 48.8 

2560 6| 2559} Decayed 100 5 6 20. 5 31.6 | 89.9 | 42.6 |__-____ 42.6 
spruce 

2541 IBS 8 Ggit eae 100} 5 6 20.5| 31.7] 95.91488]| 16.8 32.0 

ee 228 40 | Sound hem-| 105 8| 43] 20.5| 27.2] 82.0|46.0] 0.1 45.9 


ock. 
2542 3 | 542D en hem- — 100 5 6 20. 5 31.4 


ock. 
2552 4 | 552D | Decayed  as- 102 42 5} 26. 2 30.3 | 95.3 | 44.0 4.9 391 
pen. 


In the soda process the yields of spruce pulps showed a wider range 
~ than those for sulphite, with the rejected spruce wood again giving an 
- abnormally low yield. The aspen wood, No. 2552 (pulp No. 552 D), 
yielded only 39.1 per cent, notwithstanding the use an an exceptionall 
large proportion of chemical. Badlydecayed wood is soluble to a Sich 
degree in caustic soda solution, so much so that during the early stages 
of cooking the concentration of the active alkali is reduced to such an 
extent that the pulping process can not be completed. The resultis a 
large percentage of screenings and a low yield of screened pulp. For 
example, the badly decnyad spruce wood, No. 2541, was soluble in 
caustic soda (see Table 7) to the extent of 62.3 per cent. It was 
found by repeated trials that the 20.5 pounds of alkali sufficient to 
pulp 100 pounds of sound wood was insufficient for this decayed 
spruce, the yield from which (pulp No. 2557) consisted of 16.8 per cent 
of screenings and only 32.0 per cent of screened pulp. 
Attention should be directed to the fact that diese yields are ex- 
pressed on an oven-dry weight basis both for the wood and the pulp. 
[f it had been possible to convert the yrelds to a pounds-per-cord basis, a 
distinct lowering of yield with increasing decay would doubtless have been 
evident even in the less extreme cases. Such a conversion involves two 
factors: The density of the wood, and the solid wood volume per cord. 
Both factors, even for sound wood, show wide variation, so that any 
figures given for the yield per cord would be practically meaningless. 
If solid volume, rather than the number of cords, be taken as the 
basis, then density becomes the chief factor to be considered; and of 
two woods of different densities but yielding equal weights of pulp, 
that with the lower density will, obviously, show the lower yield per 
unit volume. . | 
Comparisons on that basis would be fairly exact but for the fact 
that data on the density of the woods used for the pulping tests are 
insufficient, and in some cases apparently conflicting; nevertheless 
they indicate, in general, that the progress of decay is accompanied by 
a decrease in density. This is certainly true in the advanced stages of 
decay, and the decrease in average density is doubtless roughly pro- 
portional to the increase in decay. Further investigation of this 
point would be very desirable because of its direct and vital bearing 
upon mill operation. 


CONTROL OF DECAY IN PULP AND PULP WOOD 19 


The decayed aspen used in the tests weighed approximately 2 
pounds less per cubic foot than sound wood. ‘To put the matter in 
another way: If 100 solid cubic feet of sound aspen had been pur- 
chased and placed in storage until decay had reduced its density to 
this extent, 200 pounds of wood would have been lost; and even 
though a yield (on the weight basis) were obtained equal to that for 
sound wood, say 40 per cent, the actual loss of 80 pounds per 100 
cubic feet would be there just the same. 


QUALITY OF PULP 


The screened pulps from both the sulphite and the soda cooks were 
converted into waterleaf ee on the experimental paper machine, 
and the papers were tested for strength. The data appear in Table 5. 


TABLE 5.—Sirength tests of sulphite and soda pulps made from sound and from 
decayed woods 


Atmospheric 
f conditions 
Weight Hp ae Break- 
— soar Description ras at i pound| ing | Folds |Stretch| poy. 

‘ 36—500 per | length five Tem- 

ream humi- pera- 

dity ture 

Sulphite pulp: Pounds| Pounds Meters |Number| Per cent| Per cent) ° F. 
2540 | 336 Sound spruce_--_---| 43.5 32. 0 0.74 | 5,880 785 2. 90 65 94 
2547 a Decayed spruce_-_..| 41.5 26. 8 .65 | 5,480 310 1.58 64 92 

560A 8 Bore ret ee 39. 5 25. 4 .64 |] 5,630 121 1. 88 64 92 

560 10 (Dy 3 ere ees 38. 0 25. 4 .67 | 6,040 207 1. 69 64 77 
2548 6 Di gee seas 38. 0 25. 9 -68 | 5,070 169 1. 83 64 92 
2555 9 Dt See ees 30. 0 17.8 -59 | 4,370 26 1, 62 64 93 

554 4 Sound hemlock____} 47.6 32,2 .68 | 6, 660 449 3. 46 66 75 

542A 2 Decayed hemlock -- 37.0 14.7 -40 | 4,490 137 1.90 67 72 

5428 3 DO es Et 39. 5 25. 8 40g Oy, 170 232 2. 54 65 75 

542c 5 [20 ee 38. 5 21.7 56 | 5, 950 306 2. 58 66 75 

50 | 351 Sound aspen -_-____- 51.2 25. 6 50 | 3,970 12 1. 87 65 74 
5521 1 Decayed aspen_-_--- 44.5 11.4 26 | 3,760 5 1. 66 66 68 
Soda pulp: 

540 | 109 Sound spruce- -____- 40. 0 28. 8 72 | 5,490 707 1.97 GB, jaca eee t 
2559 6 Decayed spruce_-_-| 46.0 21.0 46 | 4,770 192 1. 44 65 79 
2557 . 7 pes Fee sys bone 76. 5 25. 2 33 | 2,790 1 1.08 66 82 

40 | 228 Sound hemlock___-} 43.5 37.3 86 | 6,390 668 3. 26 68 69 
542p 3 Decayed hemlock._} 46.5 24.3 52 | 5,380 389 3. 32 64 t¢ 

552D 4 Decayed aspen____- 40.5 11.8 29 | 3,290 4 1. 64 65 72 


All of the pulps made from decayed woods show a lower strength 
than those made from sound wood, as indicated by the bursting and 
breaking-length tests. The breaking length for pulp No. 560, from 
decayed spruce, was the only exception to this ont The low endur- 
ance of folding shown by the pulps from decayed woods is very 
marked, and is indicative of the decidedly deteriorating effect which 
decay in wood has upon the flexibility and wearing qualities of pulps 
made from it. This deterioration is especially marked in sulphite 
pulp No. 2555, made from the badly decayed spruce wood. More- 
over, the pulp was exceptionally dirty. When this same wood was 
cooked by the soda process the strength of its pulp, No. 2557, was 
even lower, and the pulp was again very dirty in color. 


20 BULLETIN 1298, U. S. DEPARTMENT OF AGRICULTURE 


CHEMICAL PROPERTIES OF SOUND AND DECAYED WOODS 
AND PULP FROM SOUND AND DECAYED SPRUCE 


A knowledge of the chemical composition of sound woods and 
pulps and of the changes produced in them by the action of fungi is 
of considerable importance to an understanding of the losses sustained — 
during the storage of such material and in the conversion of wood 
into pulp and of pulp into paper. In following the earlier stages 
of decay, in particular, chemical analysis is superior to visual examina- 
tion, for an infected log or lap of uit may look relatively sound and 
yet contain wood-destroying fungi a aS had chemically changed the 
fiber, rendering it of distinctly less value as a ner ahaa material. 
For these reasons sound and decayed specimens of spruce, hemlock, 
balsam, and aspen woods and of pulps from sound and decayed spruce 
were subjected to chemical analysis, the object of the investigation 
being to correlate, more definitely than ever before, and quanti- 
tatively where possible, the chemical evidences with the fact and the 
degree of wood and pulp decay. 

The analytical methods used were those that have been found 
of value in the study at the laboratory of the chemistry of woods, 
details of procedure having appeared in the technical journals in 
various articles* initiated by the laboratory. The methds cover 
determinations for moisture; ash; solubility in cold water, in 
hot water, in 1 per cent NaOH, in 7.14 per cent NaOH, in alcohol, 
and in ether; lignin; cellulose; alpha, beta, and gamma cellulose in 
the total cellulose; pentosans; methyl-pentosans; and copper number. 


SPRUCE WOOD AND SPRUCE MECHANICAL PULP 


SOUND SPRUCE WOOD 


In order to establish a check in the present studies,>cross sections 
of spruce logs were obtained from various parts of eastern North 
America and analyzed for lignin, cellulose, and solubility in ether 
and in alcohol. These data, together with the number of annual 
rings in each log sampled, are recorded in Table 6. The samples 
were inspected microscopically and found to be sound, except as 
indicated in the table. The lignin showed variation from 26.8 per 
cent to 28.3 per cent, and the cellulose from 58.1 per cent to 61.7 
per cent. Whether these variations are indicative of differences due 
to the locality of growth it is impossible to say from the limited data. 
All of the Canadian and New England samples tested were relatively 
high in cellulose content, and those from Wisconsin and lower Mich- 
igan relatively low. The decayed spruce woods studied were mostly 
from Wisconsin. If locality were known to exert an influence on 
cellulose content, the average of the values for cellulose given in 
Table 6 would be too high for general comparison, and losses in 
cellulose due to decay would be over-accentuated. The more con- 
servative value, 58.5 per cent, obtained for the Wisconsin sample 
designated VA was therefore chosen as a standard for comparison. 


3 Schorger, A. W., Jour. Ind. and Eng. Chem. 9: 556. 1917. 

Mahood, S. A., and Cable, D. E., Jour. Ind. and Eng. Chem. 12: 873. 1920, 
Mahood, S. A., and Cable, D. E., Jour. Ind. and Eng. Chem. 14: 727. 1922. 
Bray, M. W., and Staidl, J. A., Jour. Ind. and Eng. Chem. 14: 35. 1922. 


CONTROL OF DECAY IN PULP AND PULP WOOD 21 


TABLE 6.—Chemical analyses of samples of sound white spruce wood from various 
parts of North America 


8 27 | Occasional thread 
of mycelium. 


ie eee 
Ether| “2° | °®& | Condition as ob- 
Designation : Mois-| Lig- |Cellu- “| bol of 
of aciisle Company and locality ture | nin | lose ey solu- | an- neeres ee 
ble | nual P 
rings 
iP cee Pach We. cha| Pict.) 2. cb. bP Sin. ; 
Wilt are Port Huron Sulphite & Paper | 3.3 | 26.8/ 61.7! 0.7} 0.4 64 | Occasional thread 
eae 5 Pannen, Alberta, of mycelium. 
VIIIB_______| Riordon Co. (Ltd.), Hawkes- | 45 | 28.0} 61.1 CTs 7 OL 140 Do. 
bury, Ontario, Canada. 
POE Price Bros. Co. (Ltd.), Keno- | 5.0 | 27.4 | 60.9} 1.5 .9 23 | Sound. 
gami, Quebec, Canada. 
oe fee a Laurentide Co. (Ltd.), Grand | 49 | 28.1] 60.5] 1.5 9 40 Do 
Mere, Quebec, Canada. 
VM Sree Groveton Paper Mills Co., | 5.0 | 28.1 | 60.7 Sip sled 47 Do 
Groveton, N. H 
IVA______...| 8. D. Warren Co., Cumber- {| 4.4 | 26.9 | 60.1 6 8 75 Do 
land Mills, Me. 
Id and Ig____| Pejepscot, 10 miles north of | 4.2 | 26.8 | 59.7 6 8 18 Do 
Brunswick, Me. 
] 1 ©), hk eae Hammermill Paper Co., Fort | 3.6 | 27.6 | 59.3 CARS 85 Do, 
William, Ontario, Canada. 
be See ahi Marathon Paper Mills, Roth- | 3.1 | 28.3] 585] 12 8 80 Do 
schild, Wis 
elo Lh i SAS EE ee ee ee ee er Oe Cees Cesc ee 


IMA and bx-_. Fletcher Paper Co., Alpena, | 4.2 [| 27.9 | 58.1 


DECAYED SPRUCE WOOD 


Spruce woods, Nos. 2545, 2546, and 2541, previously described in 
connection with the pulping tests and representing decay in increas- 
ingly advanced stages, together with two additional samples, were 
~ analyzed by the methods used for the sound wood VA. The addi- 
tional samples were No. 2549, a Minnesota wood nearly free from 
decay, and No. 2556, a Minnesota deadhead log taken from the 
bottom of the river. In Table 7, following the data for sound wood 
VA, are presented the data for decayed woods, arranged in the order 
of decreasing cellulose content. This is also the order of increasingly 
advanced stages of decay as evidenced by the general appearance of 
the specimens. Of the five, however, only No. 2541 was so far gone 
that it had been rejected at the mill. 


TABLE 7.—Analyses of sound and decayed spruce woods 


8 ls |S lassie 5s 18/3 4 
Bol” AGERE a\eta | | 
Sampl pe Bixecis|] S59, © |°oa| = |lo] g A 
ample Description eles] © Pe ae 88) 2 : 24| 8/88 2 Be 
o » = . 
378 |al S=92 |B) ale | Sis | ae | 4 
. OH | alaezicezio |/A/ol |alo |ala |< 
Per|Per|Per|Per|Per Per | Per | Per | Per |Per| Per |Per | Per 
cent|cent|cent|cent|cent cent|cent|cent|cent|cent|cent|cent|cent 
VA | Sound spruce, average.__________ 2. 2} 3. 8] 1.2) 8. 8/18. 9] 4. 1/28. 3/58. 5/63. 5/10. 4/26. 1/11. 8} 1. 8/0. 17 
Popa DeaAGnedG. |. Se an ce owe Se 1. 4! 1.3} 0. 5}12. 0/19. 7} 5. 9/30. 9/59. 5/60. 0/16. 1/23. 9} 9.8] 2.8) .45 
2549 | Very slightly decayed___________ 3. 4) 5. 6! 1. 5)15. 0/24. O} 5. 5130. 6/54. 6)_--__]__-__]-.-_]_--2_]LL.- . 38 
2545 | Slightly decayed, top of pile, 
Fy Te eas oe era 4.1) 6.3] 1. 7/20. 6/28. 5} 7. 7/30. 51/54, 1/42. 8/37. 7/19. 5}11. 3} 1. 6/1. 37 
2546 Gadaiiesabiy dochyed: ff tse 5. 5} 9. 7} 1. 3/89. 9/49. 2/17. 4135. 2/46. 9/27. 8/61. 4/10. 8} 9.4) 2.6) . 75 
6. 5/11. 9} 1. 4/50. 2/62. 3/23. 5138. 2/42, 0/17. 0/74. 6] 8.4) 8.5] 3.7] .61 


2541 | Badly decayed_-_-_--.-_-_------ 


22 BULLETIN 1298, U. S. DEPARTMENT OF AGRICULTURE 


The deadhead log, No. 2556, contained a larger proportion of | 
cellulose than did the sound wood. This condition is at least par- 
tially accounted for by the fact that it had been stored under water 
and the water-soluble material had been more completely removed. 
If the cellulose content of both samples be calculated on the basis of 
the residue after the removal of the hot-water-soluble portion, No. 
2556 gives a slightly lower value than VA. In any event, the con- 
clusion may be drawn that the log stored under water, and therefore 
out of contact with the air, had not suffered appreciable decay. 

The stability of the cellulose isolated by the Cross and Bevan 
method is greatly decreased as measured by the resistance to the 
action of 17.5 per cent NaOH. This resistance is indicated by the 
proportions of alpha, beta, and gamma cellulose. 

Both the cold-water-soluble and the hot-water-soluble content of 
these woods increased with increase in decay. . 

An even greater indication of increasing decay is afforded by the 
increase in solubility of the wood in caustic soda. The results obtained 
with 7.14 per cent NaOH appear to differ from those obtained with 1 
per cent NaOH only in intensity. Even in wood which has not 
reached a sufficiently advanced stage of decay to be rejected for 
pulping, the solubility in 1 per cent NaOH has risen to 39.9 per cent, 
as compared with 8.8 per cent for sound wood. ‘The copper number 
also increases with increased decay, but its changes during the earlier 
stages are not so pronounced. 

The process of decay does not appear to have destroyed the lignin. 
In fact, the proportion of lignin increased as decay advanced. ‘This 


increase can readily be explained, however, without assuming the 
formation of lignin, provided it is assumed that an actual loss in | 


weight of wood substance occurs gone decay. In this way the 
lignin, unchanged in weight, represents a larger and larger proportion 
of the residual wood. The decrease in wood density, already referred 
to, and the action of isolated fungi, described later, fully substantiate 
the assumption. " 

Pentosans showed a decrease and methyl pentosans an increase; 
but the significance of these changes is not yet clear. ; 

The resins, as determined by solubility in ether, and the mineral 
content, as determined by the ash, were not appreciably affected by 
the process of decay. 


ANALYSES OF MECHANICAL PULPS gt tg SOUND AND FROM DECAYED SPRUCE 
O 


Mechanical pulps Nos. 1AA and 2AB, ground respectively from 
sound wood No. 1 and decayed wood No. 2546, were chemically 
analyzed. The data are found in Table 8. The data for pulp No. 
1AA, Table 8, closely resemble those for sound wood VA in Table 7. 
The small difference becomes even less significant when note is taken 
of the low water solubility of the pulp, due to the removal of a large 
ee of the water-soluble content during the pulping process. 

n the other hand, in a comparison of the respective data for pulp 
No. 2AB and wood No. 2546, the decrease in water solubility is not 
sufficient to account for the more significant decrease in copper num- 
ber, Lignin, and solubility in NaOH, and for the increase in cellulose 
content. Jf account is taken, however, of the brashness and britileness 
of the decayed wood and of the abnormal losses in the white water, rt 


CONTROL OF DECAY IN PULP AND PULP WOOD 23 


may be assumed that the grinding Fyon pulverized to a large extent the 
portion of wood which had suffered decay, and that after the removal of 
this finely divided matter, as well as the water-soluble products, the residual 
pulps had more nearly the properties of pulp made from sound wood. 


TABLE 8.—Analyses of spruce groundwood pulp 


ae pe it tase | 4 | els : 
Oo o 1 peat o) n 
= A oi | 3) 
2 sg B 23 “e : D Sy 3 S, qa Pg 
tM 
—, Description Bi Pa| & (esyeties! 3181.8] 8 | a8| 2 lee 
slo" ela iasl@ | Blaiea | Bis | als 
oe = WGA. 0a aS (Fah Mh Ga A Ge a = ee = 
Pict. Pret Poet P. et.) Pct. P: ct, P: ct P5cb.| P2ct.| Piet. P. et P: ct. 


1AA | From sound wood No.1-| 06.0) 1.0) 0.4) 10.1) 18.3) 4.4) 29.7) 60.0} 60. 5) 24.5) 15.0) 11.9) 2.0 


2ABj; From decayed wood 
MINOSepdo. ote ell ee 6] 1.4) .8| 17. 7| 27.4) 6.6) 29.7) 59.6) 58.7) 20.7) 20.6) 10.3) 2.6 


~~ HEMLOCK, BALSAM, AND ASPEN WOODS 


Chemical analysis was made of sound and decayed hemlock woods, 
Nos. 2554 and 2542, and of decayed aspen wood, No. 2552, all 
previously described in connection with the pulping tests. A sample 
of aspen, No. 2551, freshly cut at Madison, Wis., was analyzed as 
representative of sound wood. Sound balsam wood, No. 2550, from 
Mininend ti, and decayed balsam wood, No. 2553, from Wisconsin, 
were also analyzed. 7 
_ The results are shown in Table 9. That none of these cases had 
reached a very advanced stage of decay is substantiated by the 
relatively small difference between the data for the sound and tho 
affected material. Further substantiation is found in the results of 
the chemical pulping tests of the hemlock, already described, in 
which very little difference appeared in the yields obtained from 
the two stakes of this wood. (See Tables 3 and 4.) The effect of 
decay is evidenced by increased solubility in water and in NaOH, 
_and by decreased stability of the cellulose as measured by the alpha, 
beta, and gamma cellulose. Mechanically, it is reflected in the 
decreased strength of both the soda and the sulphite pulps. In the 
case of the sound aspen, since the material that was pulped- (see 
Table 3) was not the same as that analyzed, the pulping and analyt- 
ical data are not directly comparable. The similarity of the analyt- 
ical data for the two states of the wood suggests, however, that 
decay had not reached an advanced stage in No. 2552. 


TABLE 9.—Chemical data on sound and decayed hemlock, aspen, and balsam 


4 . ‘a0 ra >) 1 A 
io) r= © Bm fe) 2 S r) a & 
So te 2 |S0 7 © g 31618 2 
4 ads Seolso| 2 |45|/"s al. 2 Pes ey q 
° Description (85) a6| 3 | s2/S8] 5 21° 1/318] 2 los 
a oF tel sleet! alahel ele is | 8 ls 
S| She Cha (ee ba) Bos be fe lB] 2 
a re o — o — Oo os} o nm 
a yi re debe bane | sei > yd. aio a < 
P. ct.| P..ct.\P. ct.\P. ct.\P. ct. Pere. Cb. ACh. Fe CLE, CbLP. Ct.|b.et.| Pct. 
Sound hemlock.._.| 2.9 | 4.1 | 0.5 |14.5 !21.6 | 7.3 |35.8 150.6 |57.6 |24.4 /18.0| 9.0] 2.7 OT 
Decayed hemlock_-_| 4.8 | 6.0] .7 |20.2 |29.0] 8.2 |81.0 53. 4 [51.8 /29.2 119.0] 6.7] 6.6 8 
Sound aspen__-_____ 2.6 | 3.5 | 2.1 |20.8 |33.9 | 4.8 |26.6 157.5 [58.3 123.3 /18. 4 118.9 a2 8 
Decayed aspen____| 3.4 | 4.7 | 1.7 |24.1 |32.7 | 5.8 |26.3 |55.9 [55.5 |28.6 115.9 118.3 .0 1.0 
Sound balsam -__-___ -5] 1.8] 1.0 |10.1 /18.0 | 6.1 |81. 5 [50.5 158. 5 118. 0 123.5 {10.2 | 2.4 4 
Decayed balsam.__} 6.5 | 9.4 .7 {22.8 |380.6 | 8.3 130.5 |52.8 |54.8 [27.4 |17.8 | 9.1] 2.6 ‘2 
| 


24 BULLETIN 1298, U. S. DEPARTMENT OF AGRICULTURE 


Sound and decayed balsam Nos. 2550 and 2553 were selected at — 
random from mill piles. Like the hemlock, the balsam showed a 
higher cellulose content in the decayed material than im the sound. | 
The true evidence of decay is seen, however, in the increase in copper | 
number and solubility in water and in NaOH, and in decreased ~ 
stability of the cellulose. Unfortunately, it was not practicable to 
make pulping trials on the balsam woods. 


SPRUCE SULPHITE PULP 


Spruce sulphite pulps Nos. 2547, 560, 2548, and 2555, prepared 
from woods containing successively increasing amounts of decay, 
were chemically analyzed, with results as shown in Table 10. The 
data as to cooking and physical properties of these pulps are those 
previously given in Table 3. The chemical data for pulp No. 2561 
are taken from records of work done previous to these studies, and 
are representative of pulp made from sound spruce. 


TABLE 10.—Analyses of sulphite pulps from spruce woods 


3 fe a) i © 
212 believe $|\o(5 
x nD [o>] = a fae] 3 n oO 
S 5 |2 | 8 |S.elze) 8 zi g|® 
* : ~~ O10 OD] pol kage oO 
4 Description Sslea| 6 | 3/83] 5 2) > |e lag 3 
oa & w |OS|. oe] 2] A 3 
= SE | 8 |s76*| 8 elelalelg |= 
A 6 |S |sie = |S) B/S) ais 8 
a OM /AjH Ik |O;/AlO|4+)/ mis. | a 
P.ct| P..ct| P.ct| P.ct| P.ct P.ct| P.ct| P.ct| P.ct| P.ct| P.ct : 
2561 | From typical sound wood__--_-_-__- 0.1) 0.0} 1. 1/11. 0/20. 5) 3. 0} 1. 2/97. 2/87. 5} 3.2) 9.3] 3. \ 
2547 | From slightly decayed wood No. 
DEO 2 oe ee ee O| .O} 1. 5/10. 8/24. 8] 2. 6) 2. 8/96. 1/75. 8/17. 9) 6.3) 4.6) .6) .57 ~ 
‘660 | From somewhat decayed wood 
INO. 2OO0 2 Sie Se oe 22 See .3} . 0} 1.3/14. 3/28. 2) 3.8] 1. 5/96. 5/79, 4/11. 4) 9.2) 4.2) .9) .33 
i 2548 | From considerably decayed 
WiGOG eNO. 204625 : tae eee oe .O} .0} 1. 0/13, 4/31. 3] 3. 7] 2. 1/96. 1173. 0/22. 0} 5.0) 3.6] 1.4) .50 . 
2555 | From badly decayed wood No. akc 
DESY: Oh Tee SOR RS ig ae Be ee Se TN . 3} 5. 


. 9|31. 9/52. 8} 9. 0| 1. 7/94. 4/46, 1/48. 6] 5.3] 2.9] 1.4] .81 


The pulps did not vary greatly in purity. None, with the excep- 
tion of No. 2555, contained less than 96.1 per cent cellulose, and 
none more than 2.8 per cent lignin. The progressively increased 
degree of decay in the woods was clearly reflected in the pulps, how- 
ever, by the increase in their solubility in NaOH and the decrease 
in stability of the cellulose. The copper number did not show any 
marked increase, except in the one case of advanced decay. 


SPRUCE SODA PULP 


Soda pulps Nos. 2559 and 2557, prepared, respectively, from 
slightly and badly decayed spruce, the same lots from which were 
made sulphite pulps’ Nos. 560 and 2555 (Table 10), were analyzed, 
and the data are given in Table 11. ae 

The low cellulose and high lhgnin in pulp No. 2557 indicate clearly 
its undercooked condition, which was evidenced also by the large 
proportion of screenings, 16.8 per cent, and by the weak, brittle 
condition of the screened pulp. It is not surprising to note, there- 
fore, that this pulp was still soluble in alkali to a considerable degree. 
Pulp No. 2559 also appears far from pure, containing as it does 9.6 
per cent lignin and only 89.4 per cent cellulose. . Sos 


Bul. 1298, U. S. Dept. of Agriculture PLATE XI 


Fic. 1—Ground-wood pulp stored in a wood yard on low swampy ground supporting a dense 
growth of grass and weeds. Sawmill slabs are used for a base. This is extremely poor prac- 
tice. Conditions probably could not be worse for decay at the bottom of the piles 

Fic. 2—Pile of ground-wood pulp on swampy ground. Note the surface water all about the 
pile. This yard should have been drained and surfaced with cinders before use for storage 
purposes 

Fic. 3—Fibers of sound ground-wood pulp 

Fic. 4.—Fibers of decayed ground-wood pulp. Note how the fibers have been broken up into 

short fragments through the action of wood-destroying fungi 


Bul. 1298, U. S. Dept. of Agriculture 3 . PLATE XII 


Fic. 1.—Base of a pile of Canadian hydraulic-pressed ground-wood pulp worthless from decay 
after three years’ storage on an open platform. The pile was originally 20 feet high and 
contained 7,500 tons. More than $10,000 worth of this pulp was an absolute loss 

Fic. 2.—Lap taken from near the base of the pile shown in fig. 1, showing brown strand-like 
mycelium of a fungus 

Fic. 3.—Several laps of ground-wood pulp deteriorated by wood-destroying fungi during a 
six months’ storage period in a mill basement 


CONTROL OF DECAY IN PULP AND PULP WOOD 25 


In view of the incompleteness of the alkaline pulping action, it is 
doubtful whether the chemical data for these pulps has much signifi- 
- eance with regard to decay in the wood. 


TaBLE 11.—Analyses of spruce soda pulps 


vee Bleec.| |, (2 ele | fee 

2215.41" ©|5'5|_ 0 ola \dole | ais 

BAIS S] SIP R/A,5 2 |PoaliZalao|l a |Aa 

Romie Description Es Bs ola Srila! € |g 33 "3 g21 3 = 
- cole oSalsaiVoles| 815 (a7 ($5187! 8 108! 
"AS ale 2 BI Bl|O A] .& | SLE Sols o a) a 
Oo lt a Ie Inzio |AlOl= ja [6 |a la < 
2559 | From slightly decayed spruce |P.ct|P.ct|P.ct|P.ct|P.ct P.ct|P.ct|P.ct|P.ct| P.ct|P.ct|P.ct|P.ct 
Py a Se ee poe a 0. 8| 0.2} 1.0] 3.2) 6.6} 2.6] 9. 6/89. 4/57. 1/39. 1) 3.8) 7.8) 0. 7)1.17 

2557 | From badly decayed spruce No. 

LES ee ee ee 6| .0| .7| 7.0)13.6) 7. 9/38. 3/56. 4/23. 3169. 7| 7.0) 4. 5) 2.7/2. 08 


1 Decayed spruce wood, sample No. 2560, was not analyzed, but was comparable to spruce No. 2545. 
(See Table 7.) 


GENERAL DISCUSSION OF CHEMICAL DATA 


Even the limited amount of data obtained in this study clearly 
indicates the value of chemical analysis as an aid in studying the 
progress of decay and its effect upon yield and quality of pulp. The 
analytical tests which seem to offer the greatest promise in this 
direction are tests for cellulose content and for solubility in water 
and in 1 per cent NaOH, together with possible determinations of 
alpha, beta, and gamma cellulose. It is not unlikely that a quanti- 
tative relation between some or all of these values and the degree of 
decay, as evidenced by the pulping value of the wood, can be worked 
out for the different species. A qualitative parallelism at least, has 
been clearly demonstrated for spruce woods, and this persists in the 
mechanical and sulphite pulps made from them. ‘The tests for solu- 
bility in hot water and, especially, in 1 per cent NaOH are easy to 
apply, and ought to prove correspondingly valuable. The deter- 
mination of total cellulose content, and of alpha, beta, and gamma 
cellulose, are more difficult operations, and are not likely to afford 
much information beyond confirmation of the results indicated by 
the solubility tests. Furthermore, relatively small amounts of decay 
gt to be reflected with greater definiteness by the solubility in 
alkali than by any of the other tests. 


STORAGE OF PULP 


Chemical pulps, as a rule, are stored indoors. Ground wood, on 
the other hand, is often stored in the open in large, compact piles 
oe to 20 or 30 feet high (Pl. X, fig. 1). It is also stored in unheated 
closed sheds, or in the warm basements of the mills. It contains 


about 70 per cent moisture as it comes from the wet machines. 


‘Occasionally it is eg on concrete bases; more often it is piled on 
planks or slabs (Pl. X, fig. 2) which are commonly infected with 


_. wood-destroying fungi and ready to transmit the infection to the 


stock. (See Pl. X, fig. 3.) In some cases it is piled directly on the 
ground, or on older, sometimes badly infected, pulp. (See Pl. X, 
fig. 4.) For lack of suitable storage space, piles are often placed 
on low, swampy ground amid a luxuriant growth of grass and weeds. 

(See Pl. XI, fig. 1.) In some instances piles are placed in poorly 


26 BULLETIN 1298, U. 5S. DEPARTMENT OF AGRICULTURE 


kept wood yards (PI. XI, fig. 2) surrounded by rotting débris arid » | 


subject to abundant infection from fungi. 


Storage in unheated sheds,.which naturally affords protection | 


against weathering and soot, and partial protection against air- 
borne spore infections, probably does not protect against deteriora- 
tion by fungi after infection has actually taken place. Where pulp 
is preserved with a volatile antiseptic, a closed building would be of 
advantage in retaining the vapors. | ete 

Pulp piled in warm, moist basements will be especially subject to 
deterioration, and it should not be held under such conditions longer 
than is absolutely necessary. | 


LENGTH OF STORAGE 


Because of manufacturing conditions, a rather long storage period 
is in many cases necessary for ground wood pulp. A large volume 
of this pulp is ground by hydroelectric power, the supply of which is 
dependent on stream flow. Thus, at many mills, production becomes 
seasonal and must be concentrated at favorable times; and storage 


of large quantities of material, for both local consumption and ship-. 
ment, becomes necessary over periods of from 6 to 12 months or even 


longer. 


hemical pulps are for the greater part converted into paper 


immediately, or within a few months. 
DETERIORATION DURING STORAGE 
Molds and wood-destroying fungi are the chief enemies of pulp. 


Molds cause physical deterioration by (1) discoloring the pulp, and. 


(2) binding together the particles so that the molded spots or areas 


do not beat up well—a lumpy, speckled paper resulting. Wood- 


destroying fungi decrease the strength of the wood fibers and make. 


them so brittle that they break into short lengths (Pl. XI, figs. 3 © 


and 4) in the beater, with the result that much of the pulp is lost in 
the white water and the manufactured paper has little strength. 
The combined action of molds and wood-destroying fungi results in 
the production of paper of a very poor color and quality. - 

The losses during the storage of pulp may be large. They depend 
upon the length of the storage period and the conditions under which 
the pulp is stored. 

Chemical pulps, in ordinary commercial practice, deteriorate much 


less than do ground-wood pulps, owing to their shorter storage period 


and the complete sterilization which takes place during the process of 
cooking. Molds, however, which are more likely to develop than 


decay organisms, may cause more or less trouble in the manufacture. 
of the better grades of paper; and in extended periods and poor 


conditions of storage both decay and molding may become just as 
severe in chemical pulps as in ground wood. For a further discus- 
sion see Blair (6). 

A rather common belief among pulp manufacturers is that the 


more sulphite liquor the pulp retains the more rapid will the pulp. 


deteriorate during storage. A few tests were conducted at the 


laboratory in an attempt to find out something on this point. While 
not conclusive, the tests at least indicated that traces of sulphite. 


liquor remaining in the pulp do not hasten the deterioration caused 
by fungi. | 


CONTROL OF DECAY IN PULP AND PULP WOOD 27 


The writers have had very little opportunity to observe deteriora- 
tion in hydraulic-pressed ground wood, but the information at hand 
indicates that pulp so treated will not offer any greater resistance to 
decay than the wetter laps. This is to be expected, as the pressed 
pulp still contains 40 to 55 per cent moisture. The case already 
cited of a total loss in a portion of a 7,500-ton pile (Pl. XII, figs. 1 
and 2) after storage for somewhat less than three years is strong 
evidence on this point. 

Several writers have expressed opinions as to the sources of fun- 
gous infection in fresh pulp. Some hold that infection in the wood 
carries over through the grinding process and continues to develop 
in the pulp. Acree (/), Beadle and Stevens (4) (with reference to 
blue stain caused by Ceratostomella app) , and Klemm (1/4) have 
expressed themselves as inclining to this view. Blair (4) likewise 

states: 

The process of manufacture does not affect the fungus in any way except to 
separate it into a great number of small pieces which are distributed throughout 


the pulp. When such pulp is stored, each piece of the fungus may set up a center 
of decay within the pile whether of laps or of bales. 


Sée (23), in discussing the molds that injure paper, remarks that— 


the germs of these true maladies of paper are not caused by any sort of later 
infection, but preexist in the pulp from which the paper is made, and probably 
proceed from the materials used in making paper pulp, such as straw, alfalfa 
fiber, etc. 

In order to find out whether the infection in ground wood origi- 
nates in the decayed wood used in its manufacture, an experiment 
was conducted, the material used being pulp freshly ground from 
decayed spruce at one of the cooperating mills. 

‘The wood used was abundantly infected with Fomes roseus, 
Lenzites sepiarva, Polystoctus abietinus, Stereum sanguinolentum, and 
Trametes pint. 

The rots were not so far advanced but that the mycelium of each 
of them should have been alive in all cases. Culture tests proved 
this to be true, for Momes roseus and Stereum sanguinolentum at any 
rate. Samples of the ground wood were collected in sterile bottles 
as the pulp left the grinder. A number of samples from freshly 
eround, commercially sound wood were also collected. The tem- 
perature at the discharge varied fron 120 to 180° F. (49 to 82° C.). 
At the surface of the stone, however, the temperature was much 
higher, and it should be noted that very minute particles of the 
fungus were for a short time exposed to this heat. 

None of the samples, either from commercially sound or from 
decayed wood, produced a single wood-destroying fungus when 
plated out into Petri dishes on malt agar. Some plates remained 
sterile, but the remainder were overrun with molds, such as TJvri- 
choderma spp., normally obtained from river water. As many 
plates were sterile among those representing the infected wood as 
there were among those representing the sound wood. No difference 
could be observed in the species of molds obtained on the two groups 
of plates, a condition which would indicate that water, and perhaps 
air, are the sources of infection. 

Considerable amounts of each sample were planted upon sterilized 
clean ground-wood pulp (approximately 70 per cent wet) supported 


28 BULLETIN 1298, U. S. DEPARTMENT OF AGRICULTURE. 


over water in fruit jars. These cultures were kept for more than — 


a year in an inside basement room in which the temperature was 
fairly constant (19 to 24° C.). In no case did infection by wood- 
destroying fungi occur. The remaining amounts of the samples 
were kept in the original containers, which were capped with cotton 
and cloth 
had appeared, although most of the samples were infected with one 
or two species of molds. 

This experiment is at least an indication that no infection from the 
rotten wood is carried LS 8 the grinding process. Undeniably, 
pulp made from infected wood does deteriorate faster in storage than 


. After 14 months no evidence of hymenomycete infection 


_that made from sound wood. (See Table 12.) This tendency 


would seem to be due to an increased susceptibility to infection rather 
than the bodily transfer of fragments of fungi from the wood. 

Woody or other organic materials infected with living fungi are, 
however, a common source of infection—a fact which is particularly 
noticeable with decay-producing fungi. Barnes (2) placed rotten 
pulp in sound pulp and incubated the bundles for several weeks. The 
results led him to believe that the infection would not be trans- 
mitted. This opinion is not supported by repeated observations of 
what actually takes place in commercial storage. Pulp may become 
infected not only by contact with infected pulp but also by contact 
with other decayed materials. Rotten wood floors in storage sheds 
and plank bases for pulp piles frequently infect pulp placed in contact 
with them, and the infection may pass upward through a considerable 
number of laps. Any infected wood placed within or in contact 
with a pile may spread decay. An interesting demonstration of such 
contagion occurred in one of the experimental piles, where certain 
planks picked up about the yard were used to separate the experi- 
mental material from surrounding mill stock. At the end of six 
months an infection with a wood-destroying fungus could be traced 
from the planks downward through as many as eight laps. 

The dirt carried on workmen’s shoes and clothing is also a likely 
source of infection. The soil about pulp mills is loaded with fungi, 
and even small quantities transplanted to fresh, moist pulp are 
bound to start infections, each of which may eventually involve 
several hundred pounds of pulp. For this reason it would be highly 
advisable for each workman handling pulp to keep a pair of clean 
shoes for use on the pile only, and never to wear them anywhere else. 
Upon attention to just such details, to the layman apparently of 
little import, have bash built up the highly successful practices of 
modern medical sanitation. 

There still remain two other possible sources. of infection to be 


considered: Contaminated water used in the manufacturing proc- 


esses, and fungous spores carried by the air. 
Beadle and Stevens (4) hold that little infection comes from the 


water. They advance the idea that infection depends upon the food- _ 


yielding capacity of the wood, which varies with the season of cutting; 
that in the spring and summer the wood contains, in the bai rays, 
sugars and other organic food materials which are favorable to mold 
growth; that in the fall these foodstuffs are converted into insoluble 
reserve substances, such as starch, which are less available as food 
for fungi; and that the only part water plays in the contamination 


CONTROL OF DECAY IN PULP AND PULP WOOD 29 


of ground-wood pulp, aside, of course, from furnishing the requisite 
moisture, is in its reaction upon the foodstuffs in the wood, rendering 
the organic substances more or less available for the growth of 
fungi according to its softness or hardness. They also attribute to 
the mineral and nitrogenous substances in the water the possible 
function of nourishing the molds in their early development. 

Barnes (2), on the other hand, points out the necessity of keeping 
pulp out of contact with pools of water, because “the more impurities 
an organic body contains, the greater tendency there is for that body 
to decay.” Sée (23) maintains that water used in manufacture is at 
least one source of infection, and in this Wolesky (27) concurs. Sée 
also remarks that in considering the molding of paper the sizing 
should be viewed with suspicion. 

After examining a large number of laps of pulp one becomes 
impressed with the fact that much of the infection is internal; that 
is, that many of the infected spots or areas originate within the laps. 
The decay has apparently been introduced through the water or 
through the air. Since many of the molds and two of the wood- 
destroying fungi commonly found on pulp have been isolated from 
river water used for manufacturing pulp, the inference is drawn that 
water probably plays a considerable part in infection. 

Air-borne infections must also play their part. All of the fungi 
produce spores that are more easily carried about by air currents 
than the finest dust. In the case of the wood destroyers not only do 
the fruit bodies produce an abundance of spores, but in some cases the 
mycelium may also develop them. The mature spores germinate 
readily on any moist surface; if they happen to fall on pulp they are 
likely to start new infections which may spread rapidly. For this 
reason, rotting wood or pulp should not be left in close proximity to 
new pulp piles. As for mold spores, they are everywhere in the air 
(6) but of course are more abundant where there are large amounts 
of organic matter in a state of partial decomposition. 

To prevent deterioration in stored pulp from the action of fungi and 
bacteria, then, the sources of infection should be eliminated so far 
as possible. Wood foundations for piles should be replaced with 
concrete or antiseptically treated lumber. The yards or sheds should 
be cleaned of infecting débris. Workmen should use care to keep 
infecting materials out of the piles. The water used in manufac- 
turing processes should be filtered and sterilized if possible. These 

recautions will all aid in maintaining the pulp in good condition, but 
or. complete protection it will also probably be necessary to introduce 
an antiseptic into the pulp itself. 


PHYSICAL PROPERTIES OF PULP DECAYED IN STORAGE 


In order to demonstrate the deterioration in the quality of mechan- 
ical pulps due to decay during storage, an experimental study of 
commercial pulps was made. One lot was stored at the mill and al 
the others at the Forest Products Laboratory. | 
_ The investigation began with two shipments of approximately 
1,000 pounds each, designated A and B, from one of the cooperatin 
mills. Shipment A had decayed during six months’ storage (Pl. XII, 
fig. 3 and Pl. XVIII). Shipment B, submitted for comparison, con- 


30 BULLETIN 1298, U. S. DEPARTMENT OF AGRICULTURE 


sisted of freshly ground pulp. The cooperator described these _ 


pulps as follows: 


One lot is freshly ground pulp from approximately 70 per cent spruce and 
30 per cent balsam, ground at close to 70 horsepower with a 10-cut, screw-thread 
burr, at 160° F. The other pulp is of similar wood and similar grinding, except 
that it was stored for six months in a dark, high basement where it quickly 
became infected, as the laps show. ca’ 

The decayed pulp was found to be very free, brash, and brittle, 
and in some of the badly decayed areas could be erumbled to a dust 
by rubbing between the fingers. The fiber length averaged 0.25 

illimeters, as compared with 1.09 millimeters for the freshly ground 
pulp. (See Pl. XI, figs. 3 and 4.) Under as nearly identical beater 
and machine conditions as possible, both pulps, without the admix- 
ture of other fibers, were run into waterleaf paper on the laboratory 
machine. The decayed pulp ran much freer and also showed a tend- 
ency to stick to the soins and press rolls. It foamed badly, and 
this trouble was not overcome even with the addition of 2 per cent 
size and 2.5 per cent alum. Owing to the excessive amount of fine 
fiber, approximately 8.5 per cent more of the decayed than the sound 
pulp was lost in the white water. 

The paper made from the decayed pulp was considerably darker 
than that from the fresh pulp. The difference, evident to the eye, 
was also clearly indicated by color readings on the Ives tint photom- 
eter, which gave for the decayed pulp 50.5 per cent white and 39.5 
per cent black, and for the good pulp 60.5 per cent white and 23 per 
cent black. The paper from decayed pulp was much the dirtier, con- 
taining 20 times as many specks per unit area as the other: It pos- 
sessed less than half the bursting strength and only about half the 
tensile strength, and was only one-tenth as resistant to ink penetra- 
tion as the paper made from sound pulp. 

Tests were then made, under more carefully controlled condi- 
tions, (1) to check the results obtained on pulps from shipments A 
and B, and (2) to determine the relative resistance of pulps made 
from sound and from decayed wood to decay in storage. Pulps in 
the form of commercial laps were stored at the Forest Products 
Laboratory in a room in which were maintained a high relative 
humidity and a temperature suited to the development of fungi. 

A number of the laps were selected from pulps freshly ground from 
sound and from decayed spruce, data for which have been given in 
Table 2. They were designated as pulp No. 1AA, made from sound 
wood No. 1, and pulp No. 2AB, made from decayed wood No. 2546. 
Other laps were selected from a shipment of hydraulic-pressed pulp, 
No. 3AC, received from a Wisconsin mill. This material was in 
reasonably sound condition at the time the tests began; otherwise 
its history is not known. All the pulps were stored in the humidity 
room for a period of 12 months. In the same room during this 
prsions were stored 4,000 small laps of mechanical pulp which had 

een sprayed with disinfectants and inoculated with various molds 
and wood-destroying fungi, and also a large amount of badly de- 
cayed hydraulic-pressed pulp as a source of infection for the three 
pune under observation. There was ample opportunity, therefore, 
or ane to become thoroughly infected, as they did, during the test 
period. S eh 


CONTROL OF DECAY IN PULP AND PULP Woop 31 


At the end of approximately six months, and again at about the 
end of the year, some of the laps of each of the three pulps, so se- 
- lected as to be as representative as possible of the state of decay 
throughout the lot, were made into waterleaf paper on the labora- 
- tory machine without the addition of other fibers. 

- The hydraulic pulp, and especially the pulp made from decayed 
wood, foamed very badly on the screen and paper machine. The 
pulp made from sound wood did not.. Trouble on this account in- 
' creased with the age of the pulp. | 
- The papers from all three sources showed during storage an in- 
_ crease in freeness, a progressive darkening and yellowing, a loss in 
strength, and a decrease in the average length of the fibers. 

_ ‘The experimental data are givenin Table 12. The color change, as 
measured by the Ives tint photometer, is indicated by a decrease in 
_ the percentage white and an increase in the percentage red plus green 
(yellow). e change was much more rapid in the samples from 
Hooked wood. The bursting strength and the tensile strength in all 
cases showed a decided decrease, this effect being more rapid for the 
samples from decayed wood. The rate of weakening was higher 
during the first than during the second six months, a result which 
is in accord with the microscopical and chemical observations on 
_ these samples. 
There was a marked difference in the amount of dirt and specks 
in the papers, those made from sound wood pulp being much cleaner. 


TaBLE 12.—Physical properiies of ground-wood pulps 


Color (tint pho- Strength factors at 65 per 
Green tometer) Aver- cent humidity 
Seqi-VIMt fe.) Sah Ors aes 3 gage 
Sam- menta- length 
ple Description tion of | Weight Aver- 
». 2No. test. F Red | fiber of |Points| age | Aver- 
Over- |White | Black| plus | par- | ream | per |break-| age 
flow green | ticles | 24 by |pound]} ing jstretch 
36—500 length 
Per Per Per Per 
From sound spruce: Cc: cent | cent | cent | Mm. | Pounds Meters| cent 
1AA Freshly ground. __.--_.- 91 |), 68: 5: -4205.0.)e1155 1.6 47.0 | 0.30] 2,780 1.4 
JAA BIbewOAMOMUNS-_ =... - 100-1 67.5 | 198 | 1257 .9 49.8 . 27 | 2,340 .8 
1AA2 After 12 months________- 180 | 64.6] 22.8] 12.6 1.0 46.0 .22 | 2,175 1.3 
, From decayed spruce: 
2AB Freshly ground ____-___. 100°|*62. 5") * 27.5 10.0 1.4 48.0 . 30 | 2,610 1.3 
_ 2ABi After 6 months_-___..__- 141] 56.6] 29.3 14.1 1.0 51.9 .21 | 1,990 -6 
2A Ba After 12 months________- 160 | 54.0] 27.4] 186 7 47.0 .19 | 1,780 122 
Hydraulic pressed pulp: 
3AC 8S Sig T LTT TSS aR aS ee eT ee ee Se een era eee (eee 
3ACi mtber GIONS. - 2 3.” 132 | 66.0} 23.3 10.7 La 46. 0 22 | 1,910 6 
3AC2 After 12 months_____-___- 170 | 59.8) 26.0] 14.2 1.0 47.0 20 | 1,905 2 


PRESERVATION OF PULP BY CHEMICAL TREATMENT 


_ The chemical treatment of pulp is the most reliable method of 
preventing deterioration during storage, although to a considerable 
extent decay may be reduced by the methods of storage already 
recommended in this bulletin. Molding of pulp, however, appears 
to be more difficult to control than decay. Moist pulp, particularly 
ground wood, will prove highly susceptible to the attack of fungi (so 
long as the temperature is favorable to the growth of these organisms) 
unless their food supply is poisoned by the introduction of antiseptics. 


§2 BULLETIN 1298, U. S. DEPARTMENT OF AGRICULTURE 


If it were commercially feasible always to dry the pulp below the | 
limits required for fungous growth, say to from 15 to 20 per cent, | 
or, on the other hand, to keep it completely saturated, the problem | 
would be largely solved. (See Blair and Parke-Cameron (7) for a — 
discussion of under-water storage for mechanical pulp.) od 


WORK OF OTHER INVESTIGATORS 


The writers are aware of only one reference in literature to attempts _ 
earlier than their own to preserve pulp from decay by the addition — 
of antiseptics. This is a brief mention by Wolesky (27) of prelimi- | 
nary tests, from which he concludes that 0.25 per cent solutions of — 
sodium chloride, magnesium sulphate, or aluminum sulphate applied — 
on the wet machine would protect ground wood. | 

Concurrently with the present investigation, Bates (3) has discussed | 
tests made at the Kenogami mill of Price Brothers & Co. (Litd.), — 
of Canada. This investigator reports spraying approximately 29 


tons of wet pulp with three chemicals—zine chloride, mercuric chlo- | 


ride, and sodium fluoride. The chemicals were applied as a water 
solution by means of a perforated brass pipe, which delivered about | 


5 pounds of solution per minute on a felt roll fitted to the top press 


roll. Zinc chloride was used in a 3 and a 7.15 per cent concentration, 
mercuric chloride in a 0.107 and a 0.428 per cent solution, and sodium — 
fluoride in a 1.14 and a 2.86 per cent solution. Some solution was — 
necessarily pressed out and lost in the white water. 

After treatment most of the material was piled in a storage shed. 
For the first eight months it lay in separate exposed piles at one end ~ 


of the building, in a cool location, and showed little change. Later — 


the piles were transferred to the middle of the building and buried | 
under the season’s supply of pulp. After 12 months they were again — 
inspected. In no case, even in the adjacent untreated pulp, was — 
deterioration serious. po 4 

At the time the material was put into the storage shed about 20 ~ 
laps treated with each preservative, together with 20 untreated laps — 
for each, were placed in a closed, humid kiln of brick construction — 
in the mill basement, where conditions for decay were very much 
more favorable. After 18 months this material was in a condition | 
far different from that of the material placed in the shed. The laps — 
with the light and the heavy zinc chloride treatments were badly discol- — 
ored by black fungous spots scattered throughout the pulp, the effect 
being worse in the case of the heavier chemical treatment. Those 


treated with mercuric chloride, both light and heavy, were also badly — 


discolored with green and gray mold patches, although the pulp was 
fairly well preserved from decay. ‘Those from the sodium fluoride — 
solution, however, were in strikingly good condition as compared with 
the untreated pulp, which was seriously molded and rotted. These 
tests pointed to the conclusion that sodium fiuoride in 1.14 per cent ~ 
concentration, applied at the rate of about 12 pounds per ton of air- 
dry pulp, or 4 pounds per ton of wet pulp having a moisture content 
of 72.7 per cent, probably may be used very effectively as a preserva- 
tive for ground wood. a 


CONTROL OF DECAY IN PULP AND PULP WOOD 83 


EXPERIMENTAL PROCEDURE 
TESTS AT FOREST PRODUCTS LABORATORY 


During the course of this study, 112 different chemical preserva- 
tives were investigated, with the object of finding an efficient one 
that could be applied to pulp at a reasonable cost. 

About 3,000 small ground-wood laps and 1,400 sulphite laps were 
treated and tested under laboratory conditions, in addition to ground- 
wood pulp experimentally treated in the two mill tests described in 
the Baoving section. 

Laboratory procedure was in general, as follows: On a small wet 
machine there were run off laps of fresh pulp about 25 inches long, 
12 to 14 inches wide, and one-eighth inch thick. After the laps had 
been trimmed to about 21 inches in length they were separated into 
bundles of 7 and 3. Each bundle was then weighed separately, and 
all 10 laps were afterwards spread out on a table and sprayed on both 
sides with preservative by means of an ordinary hand-operated 214- 
gallon compressed-air garden sprayer. , 

Moisture determinations showed the ground-wood and sulphite 
laps to be about 30 and 25 per cent oven-dry, respectively, before 
spraying. Lach piece of the lot containing seven laps was then in- 
aeutated by shaking on one surface from an atomizer bottle a heavy 
water suspension of the mixed spores of 25 molds. The three other 
laps were each inoculated in 10 places with mycelial cultures of five 
wood-destroying fungi grown on agar, small squares of the agar 
being cut out with the growing fungus. After inoculation each lot 
of seven and of three was folded once and then weighed for the 
second time in order to determine the amount of preservative in 
the pulp, the weight of inoculating substance being negligible. 

The amount of pulp treated at the laboratory varied from 3 to 15 
pounds, oven-dry weight, for each concentration applied. The con- 
centration of solution used was to a certain extent limited by the solu- 
bility of the chemical; but where the antiseptic value was doubtful 
and the substance easily water-soluble in the desired amount, 5 per 
cent solutions were chosen for the preliminary tests. In later tests of 
substances which looked promising the concentrations, and hence the 
amount of antiseptic per unit of pulp, were in many cases reduced. 

At the end of a day’s run the bundles of laps were taken to a storage 
house (Pl. XIII, fig. 1) in which the air was kept highly humid and the 
temperature held at 72 to 75° F. The bundles of seven laps in- 
oculated with molds were for the first few months stacked closely on 
narrow shelves, with one or more untreated laps separating the 
treated bundles, and with occasional bundles of untreated test laps 
- interspersed at random to serve as checks or blanks. For the last 
10 months of the test, however, the bundles were repiled with thick 
laps of very rotten hydraulic-pressed pulp separating the layers, so 
as to give a more severe infection. The bundles of three laps, in- 
oculated only with wood-destroying fungi, were piled on other 
shelves and separated only by laps of clean, untreated pulp. 

The increase of moisture content due to treatment varied, of 
course, with the amount of solution applied, but no records of this 
were taken at the time of spraying. 


523°—25t———3 


34 BULLETIN 1298, U. S. DEPARTMENT OF AGRICULTURE _ 


Very little drying seems to have occurred during storage, except : 


in the case of a few laps at the top of the piles before they were inter- 
piled with the decayed commercial ground wood. ‘The average 
moisture for the 81 representative laps sampled at the time of the 
last inspection was approximately 71 per cent, varying for the in- 
dividual specimens between 41 and 81. There were only 17 laps 
below 65 per cent, and 64 between 65 and 80 per cent. 


COMMERCIAL TESTS AT MILL 


Preservative tests, made at two Wisconsin mills, involved approxi- 
mately 2,900 and 4,300 pounds of ground-wood pulp. In both 
cases the preservative was sprayed on the pulp on the wet machine. 
The results of the tests are recorded in Table 13. 

Test A.—At one of the mills 18 preservatives that had appeared 
promising in earlier laboratory tests were used in varying concentra- 
tions with the object of*checking them under mill conditions, Several 
of the substances were further diluted in order to determine the 
minimum quantity effective under commercial conditions. 

The treating solutions flowed from a barrel set on a platform about 
4 feet 6 inches above the suction box on the wet machine. The 
barrel was connected to a pipe which was perforated with holes three- 
sixty-fourths inch in diameter and one-half inch apart from center 
to center, the pipe extending along the stretch roll 2 inches above it. 
All pipes were copper. A strip of cloth 5 inches wide hung from the 
perforated pipe and brushed against the pulp. The perforations 
were turned upward about 45° from the horizontal, thus causing the 
chemical always to flow to the pulp by way of the cloth. ! 

After treatment the commercial laps were piled in a moist basement 
under the wet-machine room and surrounded by the regular stock. 
(See Pl. XIII, fig. 2.) In computing the amount of chemical applied 
it is assumed that 70 per cent was retained in the pulp as it came from 
the wet machine. From 25 to 60 pounds of bulk , oven-dry weight, 
were treated with each concentration of preservative. | 

Test B.—This test at the second mill included five of the most 
promising preservatives: Boric acid, sodium borate (borax), sodium 
dichromate, sodium dinitrophenolate, and sodium fluoride. The 
solutions were made up in cold water, with the exception of borax 
and boric acid, which go into solution much more quickly in warm 
water. 

The solutions, strained through fine wire mesh, were added to the 
pulp at the top press roll by dripping from a three-eighth-inch brass 

ipe perforated with one sixty-fourth-inch holes spaced three-fourths 
inch apart from center to center. This pipe extended the full width 
of the machine, and was connected with a clean 50-gallon barrel. 
There were two globe valves in the line for regulation of flow. The 
barrel was hung from the ceiling, so that the solution had a minimum 
head of 2 feet. It was slightly tilted to one side, and a clean-out 
hole provided. The rate of flow of the solution was adjusted as 
closely as possible by preliminary trials with the intention of settin 
the second valve at a fixed point and moving only the first, as a cut-off. 
In actual practice, however, it was found necessary to regulate the 
second valve from time to time, according to flow judged by the eye. 
The tendency of the small holes in the pipe to plug was not particularly 


CONTROL OF DECAY IN PULP AND PULP WOOD 85 


marked, and could be compensated for by slight adjustments and by 
occasional picking out. With entirely clear, carefully strained solu- 
tions probably no difficulty would be experienced. 

From 125 to 250 pounds of pulp, oven-dry weight, were treated 
with each concentration of preservative. The amount of chemical 
applied was figured on the basis of 70 per cent retention, After 
treatment, the pulp, together with a quantity of untreated material, 
was piled in the basement of the mill for later observation. 


RETENTION OF CHEMICAL OM WET MACHINE 


The amount of chemical actually retained by pulp sprayed at the 
press rolls depends mainly on the pressure applied at the roils. To 
obtain experimental data on this question several tests involving 
somewhat more than 200 pounds of wet pulp were conducted on the 
small wet machine at thelaboratory. Sodium chloride (common salt) 
was the chemical used, for the reason that it can very easily be washed 
from pulp and quantitatively determined with silver nitrate. 

The salt solution was dropped on the pulp at the press roll from a 
three-eighth-inch brass spray pipe having one sixty-fourth-inch 
perforations spaced three-fourths inch between centers. The speed 
of the sheet was 41.9 feet per minute. Every tenth lap, or approxi- 
mately one lap every five minutes, was sampled for sodium chloride 
and moisture. 

In the case of a 5 per cent solution, approximately 70 per cent of 
the dry weight of salt was retained by the pulp. With a 25 per cent 
solution, the retention was somewhat greater (74 per cent), as less 
of the solution had to be 4 on to leave equivalent quantities of 
dry salt in the pulp. In mill practice some of the chemical can be 


-_ recovered bv recirculation of the white water. 


DIFFUSION OF CHEMICAL IN PULP 


The rate and amount of diffusion of chemical in the pulp have an 
important bearing on the tests conducted and are of particular 
importance in determining the commercial method of applying pre- 
servatives on the wet machine. ‘To get information on this point, a 
series of special tests with sodium chloride was begun. 

Some of the ground-wood laps used in the sodium chloride retention 
tests were reserved for the purpose, and a number of fresh laps of 
ground wood were run off at a moisture content of 71 to 73 per cent. 

In one set of tests 14 treated and 90 untreated laps were sprayed 
with filtered lake water in quantities as nearly as possible equal to 
those used in the regular preservative tests. The treated laps were 
gathered into 2 bundles of 7 and folded once; the untreated into 18 
bundles of 5 and folded once, making 10 thicknesses to a bundle. A 
“sandwich”’ stack was then built up of 6 untreated bundles and 1 
treated bundle alternately, 5 layers in all, each layer of treated pulp 
_ thus being faced with 60 thicknesses of untreated. 

In a second set of tests, 28 treated and 50 untreated laps were 
taken. Their moisture contents ranged from 71 to 73 per cent, and it 
was decided not to add water. They were folded in the same sized 
bundles as the laps used in the first test and piled together, the 
Saingy bundles being laid between 20-fold thicknesses of untreated 

aps. 


36 BULLETIN 1298, U. S. DEPARTMENT OF AGRICULTURE 


Quantitative analyses of laps from the first set were made after — 
two weeks and again after two months. The treated pulp at the — 
beginning of the experiment contained 1.16 pounds of salt per 100 
pounds of wet pulp. At the end of two weeks salt from the upper- 
most treated bundle, after an upward penetration of 20 thicknesses, 
showed a concentration of 0.04 pound per 100 pounds of wet pulp; 
from the lowest treated bundle, downward diffusion had ovidiaie | 
reached the bottom (through 60 thicknesses), where a concentration 
of 0.01 pound per 100 pounds was indicated. 

In two months the upward diffusion from the first treated bundle 
exceeded 33 laps, concentration reaching 0.03 pound per 100 pounds © 
in the thirty-third. In the sixth lap from the abs of the pile the 
concentration was 0.08 pound per 100 pounds. ai 

In the drier pulp of the second test set, observations showed that 
diffusion was going on with a rapidity about equal to that in the first. 
No formal record was kept. | 

During the storage phase of the preservative experiments at the 
Forest Products Laboratory, diffusion undoubtedly accounted for a 
certain amount of mingling of chemicals as well as loss by penetration 
into untreated spacer laps, and the lower the laps were in the pile the 
ereater the diffusion, owing to the greater pressure and closer con- 
tact of the bundles or layers. In the second mill test, however, dif- 
fusion did not affect the results, since pulps of different treatment 
were placed in separate piles. 

As a matter of preservation, the rapid diffusion of a chemical 
through pulp is high beneficial. From the facts observed it seems 
perfectly nate to conclude that any minor irregularity in the applica- 
tion of the antiseptic is quickly compensated for, and that uniformit: 
of treatment is insured. Under manufacturing conditions in whic 
every lap in the pile would be treated, loss from diffusion would not 
occur; and, therefore, smaller amounts of chemical than were found 
effective in the laboratory tests can be recommended for commercial 
practice. 3 


RESULTS OF PRESERVATIVE TREATMENTS 


Table 13 presents a record of preservative treatments applied both 
at the laboratory and at the mills. In its interpretation the foot- 
notes will help to explain certain apparent discrepancies. The results 
of the mill tests, which followed commercial methods, must be the 
final check on the value of the antiseptic. | 

In each series of tests a number of untreated laps were interspersed 
in the piles to serve as checks. Their condition was noted at different 
inspections. Except in a few cases where the laps dried too much, 
the records indicate that these check laps were severely or completely 
molded and decayed at the time of the last inspection. 


PLATE XIII 


Iture 


1cu 


1298, U. S. Dept. of Agri 


I. 


Bu 


Fic. 1.—Humidity-controlled and temperature-controlled storage shed at the Forest Products Laboratory in which ground-wood and sulphite pulps 
sprayed with 106 different chemicals were kept under observation for nearly two years. The laps in the background are in bundles of three, 
each being inoculated with five different wood-destroying fungi. ‘The experimental pulp on the left side of the shed was inoculated with a large 
number of molds. The large laps are rotten hydraulic-pressed ground wood used to increase the infection. Between these are single layers of 
bundles, each bundle consisting of seven test laps folded once 

Fic. 2.—Pile of commercial ground-wood laps treated at a Wisconsin mill with 18 different preservatives and placed in a warm, moist basement. 

This experimental pulp was piled at one side against the wall and was surrounded on all other sides by the regular-run ground wood 


ee a i to ag -» 7 


Bul. 1298, U. S. Dept. of Agricu!ture | PLATE XIV 


Fic. 1—Ground-wood pulp sprayed at the Forest Products Laboratory with a 5 per cent 
solution of borax, inoculated, and stored for a littlelonger than 14months. Thesamplecon- 
tained approximately 1 pound of dry chemical per 100 pounds wet pulp. It is free from 
mold and decay : 

Fic. 2.—Ground-wood pulp sprayed with 0.5 per cent solution of sodium dichromate at the 
rate of approximately 0.1 pound dry salt per 100 pounds wet pulp. This amount of chemical 
did not prevent serious decay and molding after 14 months’ storage, as shown 

Fic. 3.—Ground-wood pulp sprayed with a concentrated solution of sulphite liquor at the 
rate of 14.7 pounds of solution per 100 pounds wet pulp. After 1314 months’ storage the pulp 
was very badly molded and decayed : ; 


CONTROL OF DECAY IN PULP AND PULP WOOD 87 


TaBLE 13.—Preservative treatment of pulps 


[“ A” or “B” appearing in the second column refers to test A or test B described in the text. ‘‘S’’ denotes 
sulphite pulp. All other was ground wood] 


Pounds 
or. ; Months 
d chemical] Effect of chemical on Condition at time of 
Preservative ! per ton pulp agen am inspection 
oven-dry : 
pulp 
Alphanaphtylamine aptayfegt | 5. 7 Yellow._..2sesaH -}.-- 11 | Molded and very rotten. 
1h ere Risers mee ae ae OFS ne Gewvst witdeiih i 11 | Severely molded and de- 
-cayed. 
PPO ie Ha Stocco ete. 0) its ae es oa aL on ee 11 | Considerably molded and de- 
; cayed. 
Me eetleees oles | 21.9 S| Slightly brown_------. 19E Boney hat molded and de- 
caye 
Aluminum chloride, ¢. p------- 39.9 OHO Se Set ee 12 | Severely molded and de- 
caye 
Aluminum sulphate, ¢c. p__----_- 88:0. jee Ore an ee 12 Do. 
Aluminum and potassium sul-| 96.9  |-_---- GOs eee a tS 12 Do. 
phate, c. p. 
Ammonium bifluoride________- 10.9 Bleaches_._....---.--- 11 Do. 
PS 8 Ty ee 20, ee 26.8 > laa GOs felon 2 eA Bo 
Mere bs tefernn—o-erlccen.-.L- Pts a ee 0 PR ee ope See 1) Do. 
Dp ee eyes BLL 46.2 S| Slightly brown-_-___--- 11 Rormen hat molded and de- 
caye é 
Ammonium carbonate, c. p___-| 81.4 INGO 22822 2 te Bete 12 asad end molded and de- 
cayed. 
Ammonium chloride. -____.-_--- A i OO ett af 3 gc i eo 12 Do. 
Ammonium fluoride_-_-.__.___- ry, aes | RG AN ee eerie eet Bea Te ll Do. 
Oe dhtosy tee. OT ee RAR AR BAUME a's bots 11 Do. 
LO ee eee 68. 5 Britcle.. 3 see 1) 11 ; Considerably molded. 
SENT ee ET te HA) SOhb. 225 oe 2 oes 11 | Severely decayed. 
eens GA gt SJ (eae 6 ie pees oe Oe 11 | Severely molded and de- 
cayed. 
~ 23S ae ee 56.1 S | Slightly brown_-_____- 11 | Severely decayed. 
Ammonium nitrate ___..______- 103. 4 INGO! 2 3 EO: 12 Severely molded: and de- 
cayed. 
Ammonium sulphate_---____-- Lion tema ny Se GO 2acneeeatet ae 11 Do. 
Barium chloride; c. p_---_----_- |i ee age Wee ee GOwSe = ems on eats 5 13 Do. 
1 eS ae lis pam) ees Oe. 2 alge Get a 13 Do. 
C7 ee ee ee 94.8 Slightly brown_-_____- 12 | Slightly molded and de- 
cayed. Fair condition at 
> 24 months. 
Beta mapathols 2 s22 4.0.2.2... 1.0 IN O1O2 2) see Se nabs 13 peeee molded and de- 
[os | ee ea 5.7 S| Purple-brown________- 24 Slightly molded; no decay. 
Deen sonsiers = 1.) 24.7 B |. .-.-....2--.-.2-..£.-. 7 | Good condition; slightly 
molded. 
MING ee ree eg. 82.2 Pink-browne. 2-2 3k se. 13 | Slightly molded. Failed be- 
fore 24 months. 
LL TRM NS Gees aS ee 126.7 S | Slightly brown_-______- 24 | Slightly molded. 
Borobenzoic acid 23___________- 34.3 IN (cha Ve aan ae ane aaa ee 11 i SN molded and de- 
cayed. 
MINA Die eRe ne LS 63.0 S | Slightly brown--_____- 11 | Slightly molded. Somewhat 
worse at 22 months. 
Monobromo naphthalene 3_____ 5.3 NOG eine eT es 12 peyereny molded and de- 
cayed. 
Meee ks Ora opens GOs oe cede e 12 Do. 
| fh SA ESR ea ec 9.6 S! Slightly brown_-_____- 12 | Somewhat molded; no decay. 
4 No change at 24 months. 
Calcium benzoate____.....-_._- 10.9 INOTIOY Sienna ova 5 2 11 soe molded and de- 
cayed. 
BG er ee 8 ose) 205 2. [eee GO See ee oe 11 Do 
‘LD ROS ene ee ES alee aa 55.4 BES BC (oy Selon Mer ap. teh, CER 11 Do. 
(UL, rk ie se er ge a a 233.0 9 |. eee AG) 2 eee oe ll Do. 
Ae ee ee | ASS. SAS 8 3 Oe eae de 11 Do. 
re Meee Nee sk 95:3 Sieso = GO eee ek ee os? 11 Do. 
Seat is TOMAUE Rs ys ob (a: Maat Wee [0 ge fae ng an a lees Se ll Do. 
i) ot ee eee IR pi = ial (era «Vo pert re aie ges ae 11 Do. 
@hieta ehiorate...-:..... ._ 61.2 Wiellawasm 2 22-5. koe 11 Do. 
Oe - i Se ees ee 110.2 § ONG 22st yary 2b 2: 11 we molded and de- 
cayed. 
Calcium ae ae oe 86.8 03 tie pet ee Ne a 12 | Severely molded and de- 
cayed. 
Calcium sulphocarbolate______- 30.45 8 Soe "sloop tia Ie ll Do. 
TDS 2 od ee eee 95.6. ‘Ss = se (gia bs See eee 11 | No mold or decay. Slightly 
molded and apparently 
somewhat decayed at 22 
: months. 
Carbolic aid. 2... 2 ee Severe OOS. tes oka 13 | Somewhat molded; no decay. 
. Failed before 24 months. 
Carvacrol oil No. 5 5 6__________ 3%.0 Ae 22 (6 (0) alae Ec Spee 16 | No mold or decay. 
Carvacrol oil No. 47) 6__________ 37.0 A } Slightly pink_........- 16 | Very slightly molded. 


See footnotes on page 43. 


38 BULLETIN 1298, U. S. DEPARTMENT OF AGRICULTURE 


Tas_LE 13.—Preservative treatment of pulps—Continued 


ae 
(0) 
: : Months se ne 
ndenreatiea? prey Effect = erage on iA Ce of 
oven-dry storage o 
pulp : 
Carvacrol oil Ne. 1 8 6§_______ _- 87. 0A ch None eee 16 | Slightly molded and de- 
caye 

Dolor ay bis Dow 912.0 Brown. -2.4augt_ te. = 24 slightly molded; no decay. 

Dott. behing, _ caer bs 269.0 S | Slightly brown_-_--_--_- 24 | No mold or decay. ag 

DO Ses ITS 463.018 )|-2 GO 2 a es 24 Do. ‘ 

Chromium sulphate_____-_-_-_- 96. 3 iBluishi26322 5520 Lee 13 cone molded; slightly de- 
cayed. 

Dog Debio. Sei WANs.) 95.1 A | Slightly green._-_-_._- 6 | Severely molded. 

Copper acetate... 28822922). 9.7 INGNES 2 ae eee 13 coo molded and de- 
; caye 

OMe soe. oe. See 18.5 A | Slightly brown-_-_----- 6 | Somewhat molded and de- 
cayed. Failed before 16 
months. 

DOT ee eee ee 1S ee doe ss oe 13 a molded and de- 

4 aye 

Dos ste ee ZEB IA AS POI oh 2 6| Somewhat molded at 6 
months; considerably at 
16 months. 

DO. 2 ea 37.1 Browns. 3 eee 13 | Somewhat molded; no decay. 
No change at 24 months. 

DOs 236 eee AD. at Salas 6 0 ee es ee 24 | Slightly molded; no decay. 

Do... ee eee 9.7 S| Slightly brown-------- 12 ee molded and de- 
cayed. 

DO) Soe eR eee 20:0) $5) 2-25 G0. 232223 ee 12 | Somewhat molded; no decay. 

Do Hie OL Tis beable. Fp 41.0-8.|-Browns=-22 bef 12 | Somewhat molded and de- 
cayed. 

Pe ete Mt ee 65.9..5- |= 2--sdo-<+=-00. 2 hee 12 Do. 
Couper bromide___. 72240" 5 | 29. 7 Slightly brown_------- 12 pares! molded and de- 
cayed. 
i chloride: . ze _L BY Ey eee ere G0-22 22-280 13 | Severely molded. 
Ces Stee = eee Oe See 57.4 222 200s ee ee 13 | Severely molded and de- 
cayed. 

DO: sos see Oe ee 89. 7.2228 c Va een ee a 13 | Severely molded; no decay. 

DOE oo. se ee 100. 3.-8- | “Brown. 2508-2 se 8 12 | Somewhat molded; no decay. 
Somewhat decayed at 24 
months. 

Copper fluoride-_......-..--_-_- 7.4 Slightly brown_------- ll sore molded and de- 
cayed. 

[Do. fos) ee LOSS a|- 5 Q0o225. 2 Se 11 | Slightly molded; no decay. 
Severely molded at 22 
months. . 

Copper nitrate, c. p_----------- 48 whee ia a ee 13 ee molded and de-— 
cayed. 

Do... See see Le COP Trt: 3 GOs 32 2 eae 13 Do. 

Do: 2s OV ae 64. 18) {== 0 oe. eee ea 12 Do. ’ 

Copper sulphate-__.__-._.--_--- 77.9 Brown: 222-782 %bo A 13 cee molded; slightly de- 
cayed. 

IDOI: . MOORS Sane ee 119:.7 “8 |2se29 0.04 See ae ee 12 | Somewhat molded and de- 
cayed. Failed before 24 
months. 

Cypaene (crude) 2. Senior) 2.4 None =) 28-8 ere 10 | Severely molded. 
cA ae RHE ne Se Ra aN oe 160. 0 oes Pador* 2 hte* saps 6 | Somewhat molded. 
CHitiens and naphthalene ® 10 <a Stee 53 (oa Soot to 1 GH 10 Do. 
(equal parts by weight). 

D010 SROs Eee aL 2 ONR | soho 60:2 ae 10 | Slightly molded. 

Do. Ds Se 2 2 ee NS a do. 266 eee 10 | No mold or decay. ~~ 
Dichlorobenzene--_.-.-_._-_--- 7 Vole, poder sc Goss ae ees Fe 6 | Slightly molded. 

Oona. Se eae AO rh =m docs eae 6 << slightly molded on out- 
: side. 

Dot oi eae te B2EO reins om Fi (0 Paetpemiete thet rey 2 a, 6 | No mold or decay. — 

OCs. eee he ees AS OM ea2- a5 dO 2. SE sere 6 Do. 

BD ON.) eter eee eee nee BO Ose se G02 eee = 6 | Slight mold on outside. 

Ferric chloride, U. S. P____-_-- 37.9 Brown: 32274 -aees 13 cere molded and de- 
caye 

Ferrienamitrate st re 92.7 Darkened 244 FA. Se 12 Do. 

Ferric sulphate, c. p__-_---____- WG Soe C0 ren 12 Do. 

Paraformaldehyde sere oes bo 32.1 None. so“ Sse a he 11 Do. 

DOR. as eee We. Oe. shes (6 1 anne RN ea, apt Br 1l soe molded and de- 

G0. Cel eres OE Le 60: 9-84 222 0 (0 )edaeaipime Seneiad so 4 11 Slightly molded; no appreci- 
able decay. Considerably 
molded and decayed at 22 
months. 

BOE Lewes Lay Wie pA TIS: 048s 5a" (oD Seteingem yebaeseinged slip 11 | Severely molded and de- 

4 {  cayed. 
See footnotes on page 43. 


CONTROL OF DECAY IN PULP AND PULP WOOD 39 


TABLE 13.—Preservative treatment of pulps—Continued 


bg 
re) 
pte et et chemical | Effect of chemical on pheaits Condition at time of 
- per ton pulp storage inspection 
: oven-dry 
pulp 
Hydrosilicofluoric acid !°_____-- 44.9 BrOW Disc see do ak 13 Oat molded; slightly 
ecaye 
ME Re UeL LEO OGTO LS 2 as | i Ie cee se Oe 13 sigcaly molded and de- 
cayed. 
Lactic acid) 'U: 8. Poo. 222..-.- 61.1 Slightly brown__-_--_--- 12 Do. 
ihead acetate peslem yi se 45.0 None’ led esom0e. 2... 13 | Slightly molded and de- 
cayed. No change at 24 
months. 
Oe ted ucamal B60 Aso doe. Oh 4d. .- 6 hom molded; slightly de- 
caye 
UT 69.4) Ae (i (oR ne ee A 16 Severely molded; very slight- 
ly decayed. 
[Qe ot ee ee (6251. tee do_--. we. 13 | Severely molded and de- 
cayed. 
atone 2 reer FAe vest 4523) 8.) eS. do: hb... S. 12 Do. 
eet: $590 emcees oo. TEE 6 yl aie ASE EY VA it me 
Dead wntratesiwo_ ied cecil. 90. 3 Slightly brown_______- 12 Do. 
ty Se Sr 99.0) (Si3| Pinkish >= O57). 12 | Somewhat molded. Slightly. 
decayed at 24 months. 
Toysciies ete ieee: i 96. 4 NOne@ei sess. eb -ed od 13 | Considerably molded; no de- 
: cay. No change at 24 
months. 
mage ammonium chlo- | 102.3 Slightly brown___--_-_-- 12 Whoo molded and de- 
ride cayed. 
Magnesium chloride_-_-_______- 24.9 NOneS:)hedezck at 13 Do. 
Mirena reindeer heen so yal Le | C022 52253025 ee 16 Do. 
Magnesium nitrate, c. p_______- oe es ae d0.2:4 AS Se 12 Do. = 
Magnesium silicofluoride 1ae5_2 J 2): Sa | Cee doe... Aaa 11 | Severely molded; no appreci- 
able decay. No change at 
22 months. 
Tae Pee ee es BOM. | oe wet ie te Ak 11 | Somewhat molded. 
1D ee ee Braor.o. eNOnessce2 =< ee ek 11 | Considerably molded and de- 
cayed. 
(ee a SS TAS IE Si, [422 oe Ot 20> een ee et 11 Do. 
Mabteciara: sulphate____.-.___- Beds P| ee Coweta sido atl) 12 ge molded and de- 
cayed. 
Manganese sulphate__________- O02 a alee Co Yee er RS Sarre 12 De 
Mercuric acetate 13___-_....____- 8.1 Slightly brown.______- 11 | Somewhat molded and de- 
caye 
ib ie 2 ee NORGE File ye Co Lo ey | Caeaepmen Sara 11 Do 
Do feather t! | TIE OF Gils) eet lo! 11 Do 
TO Ta) SS ae eee ee Dis Mash Ul ye rg ee Ree Oo 11 Do. 
Nickel sulphate. __iic0-<---|- BOneR NT ee tyreee. 5 UI oat 2g 12] Severely molded and de- 
cayed. 
Mononitrobenzene aS a 6. 4 NOne geusere tant b=. 12 Do. 
eae wprgs-——1- (A. erg need en ieee, ae 12 Do. 
LT AIS a Rs os OFF. As lem eet GOs cigelge 5 feud Be 6 | Severely molded; somewhat 
decayed. 
1D ae ope eee 1 een | ge aS GO! 22 sererceyft 2b 8 6 | Somewhat molded and de- 
cayed. 
SO ess | ane ae See ely 1) ess eee G0ee 2th: <2 oe 12 | Somewhat molded; no decay. 
No change at 24 months. 
Dinitrochlorobenzene --_______-_ or ine x |v teres Goi 20 pap ie- kes 11 | Somewhat molded and de- 
; cayed. 
3) SY 5 ae 6. 2 Slightly brown_--_-_-__- 11 | Slightly molded. Consider- 
ably decayed at 22 months. 
| DY a a ee 10.0 BTOwsl ee eS 11} No mold or decay. Some- 
what molded and decayed 
at 22 months. 
WM Betiteon. - theses. 8 | 2 5.8 S | Slightly brown_______- uy Do. 
ee ee CU! GN: a (aaa Ceres eel Se aE 11 | No mold or decay. Slightly 
molded at 22 months. 
eeraeee eg r - 8 2025 lose Git aS Sete oe 11 | No mold or decay. Some- 
what molded and decayed 
3 . at 22 months. 
Orthonitrophenol !4____________ 24 Slightly yellow________ 12 | Severely molded and de- 
cayed. 
LO Ce ee oe ee Zee he 3) | 8S Ce eee Cee 12 Do 
SUS ee eee CSG ea Pee ge ee 12 Do. 
lige: ee ae aan SViOliOs ee ech eh ie 12 Do. 
i Sia a oe ey 7.0 Slightly brown_______- 12 Do 
‘DS eer aa a Sa sa Cee ee a 12 Do. 
ee a eee ee 6.8. ‘S| Darkened... -n6' 2. 12 | Somewhat molded and de- 
Do. "4 cayed. 
as eee 9:4 8 | o2esegee yitefoite |b | 12 Ge eideratly molded and 
decayed. 


See footnotes on page 43, 


40 BULLETIN 1298, U. S. DEPARTMENT OF AGRICULTURE 


TABLE 13.—Preservative treatment of pulps—Continued — 
Pounds 
phate ditty dtigmiical|: Sétéet Of thaesteat tu, ante Condition at time of 
per, oe pulp storage inspection 
pulp 
Paranitrophenol?________.--__-_- 2.0 None. ease tS 6 Reve molded and de- 
caye 
Don. tebines wer sags "A ee [el ha (Ol eater reneged oe 6 Bomenah molded and de- 
cayed. 
Dinitrophenol Rien 5 a Ls Seep 2.0 Slightly yellow_____--_- 6 | Considerably molded. 

Dp sateleyies_ selgeieg te 2 4.0 Somewhat yellow _-_-__- 6 | Slightly molded. 

Mononitrotoluene___-_-_-.____- 1.0 Slightly brown__-_-_-_-_-_- 6 | Severely molded. 

Woe 2 el aeteg oe 7A 1 egal | eae On oe: tert eee 6 Do. 

Woz) ahinus steyrrat hy Sy eee | Eales 6 (1 eae =| 5 SRN A 6 | Somewhat molded. 

Do.8 2 2 ee 1p He R00 1 ane PO TF 12 Rerey molded and de- 
cayed. 

DOs. 2. bereeeb eh. 8.0 Slightly brown__-_---_-- 6 | Somewhat molded. 

Paes. . Peathis st oleae 15 10. 4 INIONS. 3 a ee 12 Sexy. molded and de- 
cayed. 

Dc! Sa” 4 ewe 1 8: 408 433 d0:22=-8. oe 12 | Somewhat molded; nodecay. 

: No change at 24 months. 
Orthonitrotoluene 15____________ 4.6) A |. ened waste, to 6 Barer . molded and de- 
caye 

Magsars Meta hey eas i be ZORA We=- se CO! 2 eee ee 6 Do. 

Dos Matiiguny sidasohisa jb 13.8) Adj. 00.. 2 ee 16 ges appreciable mold or 
ecay. 

Dinitrotoluene 14__________._-_- iet Slightly yellow-_-_------ 12 ieee es molded; severely 
ecaye 

Dor 2. 2 eS BiCe Wes 3 bp i ease Sogn oe 12 | Severely molded and de- 
cayed. 

1D Yigal Saat eS 8.2) Sul. ee oe ee 12 eos molded and de- 

Oxalipiseid. betta _siegereit 41.9 Notte. 22. 80. oos2e 13 severely molded and de- 
cayed. 

DO. 2 OT a 79. 0 Pinkish® —-.- >) aes 13 Do. 

Doz... peMegt tad wane 50: 1S None. 2 ee 12 ae molded and de- 
cayed. 

1D [i gaia Meee fs pee S 83.8 8 | Purpiph- oe 12 | Somewhat molded; slightly ~ 
decayed. No change at 
24 months. 

Potassium bromate___________- 91.5 None: 22 S22. .- meses 13 | Somewhat molded; no-decay. 
No change at 24 months. 

Potassium chlorate_____________ 52.6 Brown stains_________- 12 wets f molded and de- 
cay 

DO... tie ee ee ee nis 2 (ee eS Ok. a0 So S55 12 Do. 

DT yg SS. RR Se 44.9) ia) NONGo.5. 2s5esssesl 12 | Somewhat molded. te 
somewhat decayed at 24 
months. 

BO! ee ee oe 04 ANS Ao GO yer ees 12 | Severely molded; somewhat 

ecayed. 
Potassium permanganate-_-______ 7.0 Dark brown_-___-_____- 13 Sere molded and de-— 
cayed. 

Does he bien “errsives 2 1A Ol oleae G6... 00a 13 Do. 

Do... 222-1. Reet 1 US? ame | Ge G6) 20. ree 13 Do. 

DGS, Yuma. jab Keues 1 11.4 .S- Brown. 2.--00..22.5 12 ae aes molded and de- 
cayed. = 

Wott, bebions tamycure eee at 14. 7S esas G0. vet ss eee 12 | Somewhat molded, severly 
decayed. 

Potassium silicofluoride________ 11:2 None::...- ieee 11 Severely molded and dae: 
caye' 

WG. 2. _ oes sin ais: 20.2 S |..--- Wong wees os 11 Do. ‘ 

Quebracho extract..........__.. 104. 5 Brow. t= eee 13 | Somewhat decayed. Failed 
before 24 months. ? 

GL. Dat pomoin tis 2: Danan: SU |e 2 d0..3-.53 = See 13 | Somewhat molded. Failed 
before 24 months. — 

Slot Mi oo are cee 6.9 Nonezos:_ viidals 11 | Severely molded and de- 
P cayed. 

Deters ie bebiogr ty bee Oh ae d02 So eee 11 Do 

Pio Ji eet yl Higa ee -F 1 SS eae do..:.. OR.. ee 11 Do 

Dele eink Levies Jeg} i308 8 = G0... es 11 Do 

O42) 2 eal ei ge SS te. 5 9 26:5 Sa 06:2 eee ll Do 
Sodium acetate__...__._________ S018. gee ois Giiyie P59 12 Do. 
Do. 2 eee 102.6 S | Brown stains__________ 12 Severely molded; no decay. 
No change at 24 months. 
Sodium aluminate_-___________- 82. 1 Slightly brown_____-__- il ee molded and de- 
Rips Oy ate eee ie 118.1 § |... dovwd visa tb 11 Somewhat molded and de- 
Sodium arsenate, c. p _________- 43.0 None: aametrael 1 24 Slightly molded; no decay. 
Dos ts -23 ee 2 Pic: Pabiee) aber G0 eee oe ee 24 Do. : 
Dositon: . viiaraebiegy.):) § 56.7 S ‘ Slightly brown---..-.--. 24! Do. ne 


See footnotes on page 43, 


CONTROL OF DECAY IN PULP AND PULP WOOD 41 


TaBLeE 13.—Preservative treatment of pulps—Continued 


oan 
or ‘ Months sie 3 
: chemical | Effect of chemical on : Condition at time of 
Preservative ! per ton pulp Byes a inspection 
oven-dry 
pulp 
Sodium arsenate, c. p_________- 107.9 S | Slightly brown_-___-_- 12 | Very slightly molded; no de- 
cay. No change at 24 
months. 
Sodium arsenite, c. p __--___--_- 102.8 INONG 222 24 | Slightly molded; no decay. 
Nags eee | NO 94:6 8) hee CLONE ee yee he 12 | Considerably molded; no de- 
: cay. No change at 24 
months. 
Sodium benzoate-_..__..____-_-- Taras" eee (6 (0 ee ely, ee iL ove molded and de- 
cayed. 

TG OMIT MIE Ce 4, 4> ---peeeee 3 0 ee ee a 11 Do 

UL A ee ee 70. 5+ << +fene CO es 11 Do 

parecer ress 2 Sree) 8 t 1922"S) |aos 0 Ki eee lg oy a 11 Do 

eee SN sf 52.4 S | Slightly brown--__-_-_-- 11 Do. 

Lode, 2 Se aS 100. 2:'S 2c<: Agee Ne 11 | Severely molded; somewhat 

decayed. 
Sodium bicarbonate________---- 109. 3 12 ee molded and de- 
pe ONES 203. 1 24 Slightly molded; no decay. 

ID iti a eS a 106.2 §S 24 Do. 

—Ailte ths SLE SS ee 188.1 S 24 | No mold or decay. 
Sodium borate (borax) -_-_-__---- 54.1 B 7 | Severely molded; no decay. 
ee eee Se 83.7 A 6 | Considerably molded; no de- 
: oar La, No change at. 16 
een ae een OYTO CONG tate (0 atte a tec Cae 24 Slightly viinided: no decay. 

Mer meetee eee es Ee et 130. 2+A+|s--2 CONE CUES She 16 Do. 

Tog eee OMT ERG Wo 135795 eels dOssse see fe 13 Slightly molded and de- 

cayed. No change at 24 
months. 

We ee $9566 Sos gS = 3 So eee 12 ey, molded and de- 

caye 
Sodium bromate, c. p_-.------- SUG < = [eect ede = Packt Ys. 12 Revere molded and de- 
caye 
Sea Sar IMIELY DER 125.7 S | Slightly brown-___----- 11 Do. 
Sodium carbonate_____.._.____- 124.8 TOW Des ee ee 13 | Slightly molded; no decay. 
ee 173. 3 2 ATG 0) eae erent Dears 13 | Somewhat molded; no de- 
~ cay. No change at 24 
months. 
Mpg DOONEY 125.5 S | Slightly brown_-_-_--- 24 | Slightly molded; no decay. 
Mee BOT OWS PON 204.1 S 10%.) 06 Re ea RR 12 | Somewhat molded; slightly 
decayed. No change at 24 
2 months. 
Sodium chloride (salt) __-_._--- 174. 6 INONGs2ecsecceseesl Le 12 seat molded and de- 
cayed. 
Sodium citrate___...._....._.-- 83. 5 Slightly brown-_.--.---- 13 Consicerably. molded and 
ecayed. 
Sodium cyanide____.__-.___---- 91.3 IBPOW NE: 32550 2 eS 12 Pere? molded and de- 
cayed. 
in ee 106. 5 PAPE “a (0 SS ee SD spree 12 Oo. 
Sodium dichromate _________--- 4.0 Wonesni. UP a oo 6 | Very slight molding. 
wey ey i ERAT 8) AS ee ee SE Se 7 | No mold or decay. 

Dyas peee I AS? ee 8.0 Slightly darkened_-_-__- 6 | Very slight molding. 

13.5 3 ES ee re 10.6 Gheeee ie) 8 13 Peversly molded and de- 

cayed. 

epee aprons SIT 13.8 A | Slightly yellow__._.__- 16 | Very slightly molded; no de- 

cay. 

gee Saat FG eae Os 16.0 Slightly darkened_-_-__- 6 | No mold or decay. 

BD Qe wee SA es 20. 6 ONES eee 13 penne molded and _de- 

cayed. . 

US A, 2 a 27.8 A | Slightly yellow_____-_- 16 | Slightly molded; no decay. 

oy SAS 1 ie a 32. 0 Slightly darkened__-__- 6 | No mold or decay. 

iD te. i a ee 33.5 | Slightly yellow--_____- 13 a molded and de- 

cayed. 

LOD) aan a ee gs 740 Rial oso 6: eee at ee 24 | Slightly molded; no decay. 
inte Th, Fe 41.3 S | Yellow stains__._.____- 12 Soest molded; slightly 
; a 

Sodium fluoride_..._._-_-_____- 8.0 Bh eeab si  e 6 Slightly molded. 
rgeeteee St 16;0--- eee 9 C0 epee) ta 6 Do. 
£2 las pl a 18; 6 Av lec 22 CO ee emt 6 Considerably molded; no de 
cay. No change at 16 
months. 
nee 21-9 Besa CO a lie MS IE 7 | Slightly molded; no decay. 
temas EU stOL! 2. 2.8: Blea ses LAO papa ae ata Bae 6 | Considerably molded; no de- 
cay. No change at 16 
months. 
Geo. sackets Ma RAT Pag Aas, (Lo) tuts Beha otteeg se Mecetpl 6! Very slightly molded. 


See footnotes on page 43. 


42 BULLETIN 1298, U. S. DEPARTMENT OF AGRICULTURE 


TABLE 13.—Preservative treatment of pulps—Continued 


Pounds 


fe) 
chemical} Effect of chemical on Condition at time of 


Preservative ! in : : 
poe ees pulp storage inspection 
pulp 

Sodium fluoride.......-.=--.--- 37.2 A | “Nonepcaesuecte be 6 | Slightly molded; no PRAY 
No change at 16 months. 

DO.) -- +. ose eee 48.0) Gisccce “CC ages ms 5. 6 |-No mold or decay. 

Dios = -batis-e uiidosie fo BAST en G0... jaa tee 12 | Slightly molded; no decay. 
Slightly decayed at 24 
months, 

UD ae en eld eee CE SG, Wd teaone 3 1 Pi ees rpc WO 12 | Severely molded and de- 
cayed. 

Digs eo ee oe ees Bist fences 1 Seat epetbatabes a8 24 | No mold or decay. 

1D Yo Waa aie eae. aimed 2 86:0. 5.|-22- co Loonie’ settee Sof 24 | Slightly molded; no decay. 

Sodium nitrate_.._..2-ce-__..63 CAST ieee beeline (0 | aE Sit dialed Set 12 ceva? molded and de- 
cayed. 

Sodium paranitrophenolate.---} 1.1 |_----do-.---.---.-.---.- is | aa 

‘LEY oS OY TRE A ARN etyeee she #8" 2.0 Deep vellow ee eee 13 Do. 

D0 aa a a er eed Ode) Posse Oe se eae aot ee 13 Do. 

DO4s Get ieys . piaeeeente Le Ne | ee do ae oe B 13 Do. 

J DY ees Siete - 2 1 ah Sean er 9 (5 Paglia eee e oo 13 Do. 

DGObtecs -Boitesaeledieite 43 1,58 Slightly Vellew =o. - 12 Do. 

by aie cee Reiser +. neni nal 0 2:6. 8 |. -- Seeks eats oe 12 Do. 

D032 ragsfe se bine: oh Ay I | a ey Pee Se 12 | Somewhat molded and de- 
cayed. 

DO secbta gs let een htemna ts te 9.3" S ||. - eed ete tse aes 12 | Severely molded and de- 
cayed. 

W02 5220200 beepe eo P7 A (i sl Plea cain EP Pa eg 12 ae molded and de- 
cayed. 

Sodium dinitrophenolate__----- 1.1 B | Slightly yellow_-_____- 7 | Very slightly molded. 

De, 2 Sail wt oleae es 1s Baa ee 0053 ai ee 16 | Somewhat molded; no decay. 

DD Gaze che ath. eee cee Ii glee ses (0 (0 inundated 13 | Slightly molded; no decay. 
Slightly decayed at 24. 
months. 

DOT 222. ise. Ree ares 1S ae Oss 22526 Mee ee 16 | Somewhat molded; no decay. 

IDOu-. Bees siegee eS Pe Ate ee OS 2 er er ees 16 Somew nas molded and de- 
cayed. 

1D Oss). ees eee ee 2:1. B | Yeollowed 3 4aexe 4 e2 7 | Somewhat molded; no decay. 

Do... 28h Ge ee Ss 7 a tale (PSE Zs G0_= 2. eg et 13 | Somewhat molded; no decay. 

2 No change at 24 months. 

Osea 2 ee oe 45008 |oecee COL. 325-25, a= 13 Berets molded and de- 
cayed. 

DO shah oie tee Es 6.5 Deep yellow------_--- 13 | Slightly molded and de- 
cayed. No change at 24 
months. 

DO: 2 255i eee oS 1053.) Sapa Oh: Soe he eae 24 | Slightly molded; no decay. 

Doss Baha 4 eae ee DSS eee eee 12 | Somewhat molded; consider- 

‘ ably decayed. 

DG@st4c-c. | thteectiteenti Bs 2.9 S | Slightly yellow__------ 12 | No appreciable mold or de- 

! cay. Slightly molded and 
decayed at 24 months. 

190... 2. _-..5.-= pee ee 6.7 8 } Yedowicce-. ee ee 24 | No aporeeaae mold or de- 
cay. 

DO! Setites: pie sete oa tS Ape Ms Bl GOs 2522. sheet Se 12 | Somewhat molded; no decay. 
No change at 24 ‘months. 

Do. sein go pits wee 21.3 S | Deep yellow_-_-------- 12} No mold or decay. Very 
slightly molded at 24 

5 months. 

Sodium phosphate, monobasic-_| 82.8 Nonetiss-sitesu? 2 12 | Severely molded and de- 
cayed. 

Do:...+saatbaec bee 2e 80.0) ° | gece COs eh tee fee 6 | No mold or decay. 

odium phosphate, dibasic,e.p_-}| 48.0  |_---- C0: -.< sacs eee 6 | Somewhat molded. 

DG... fapems oe i a pa NE 6 Do. ; 

DoOh< oo -baiiece siteeee SS 95.1 A j_. oes etedego Sake 6 | No mold or decay. Consid- — 
erably molded at 16 
months. 

Sodium phosphate, tribasic____| 48.0 NONn@. 22522242 5555--o9 6 era | molded and de- 
cayed. 

i 8 Yc eae) rg Ree, iP aD fart S050) re 2s G0tes. edb Eee 6 | Slightly molded. 

Soduim salicylate_..........._- 53. 7 Very dark. .s:2 25.222 - 12 oe molded and berg 
vege 

1 0 meager ee Se Neape  s SET S TOPS le se Cs (ems TA ee ta 12 

POPs lee Lette tenes 2S 49.2 S | Slightly brown.-_____- 12 Seuabers molded; no decay. 

DOs sspears cual 6. ss kek! Bee 06:4" Sate Te See ea ae 12 Do. 

Sodium silicofluoride__________- 34. 1 Wione--: 8:22 255 eee 11 | Slightly molded and de- 
cayed. No change at 24 
months. 

D0: 2662s: alas sae oe 59:2) Bj2seee 6 { Ee REN ae gs 11 Do. 

Sodium sulphite, c. p_...---____ 157.7 Slightly brown_-_-__--_- 12 Severely molded; consider- 


* ably decayed. 
See footnotes on page 43. 


Oe eee ee ee 


CONTROL OF DECAY IN PULP AND PULP WOOD 43 


TaBLe 13.—Preservative treatment 0, pulps—Continued 


. 
Pounds 
C9) 
Bier vative | chemical} Effect of chemical on ert ae Condition at time of 
per ton pulp storage inspection 
oven-dry 
pulp 
Sodium sulphocarbolate-_-__-__-_- 56. 4 INIONCs {hen tes ¢ «depe a 11 aq ometes molded and de- 
cayed. 
U0 2 ee TIN ce ye tev np hegre ee Pe ee 11 | Considerably molded and 
decayed. 
Sodium and potassium tar-| 75.4 Slightly brown__-_____- 12} Severely molded and de- 
trate, c. p. cayed. 
Sodium thiosulphate (hypo)-__-_} 218.5 None Siti ies. 12 Do. 
Pampemexiracu. 2... =~ 192. 4 BLOW eset aa eee 12 Do. 
Mltymel ees tet etry iris 0.2 WOM Ye ses Sees | 539 13 Do. 

iD oA eee ee O: die hf aeest Gon. 5 Tae? ees 13 | Considerably molded and 
decayed. 

[ROR SSS a ORDA Sat GO se, BSE 6 | Slightly molded and de- 
cayed. No change at 16 
months. 

(Dit. 2622S ee ee OL Oe Eee be: CO (a\o SERS aay ees 13 | Considerably molded and 

ecayed. 

Lich Si Sits Ss eee 1 OS AG aes AGEL Rg 2 ee ee 6 | Slightly molded and de- 
cayed. Somewhat worse 
at 16 months. 

Thymol oil No. 28, 17____.______ LS Ow | aee GOES Bee hy es S 16 | Slightly molded; no decay. 

DOA Aa sae a Oia OPA CELE S: dors. Pa 16 | No mold or decay. 

Thymol oil No. 38, 18__.________ DOTA “20. ! ORS Se Sgr ay 16 | Very slightly molded. 

“Dinse 0) bent Al elias mn ORGS. ire 2 BO ep atte, A, Del 12 | Severely molded; somewhat 
decayed. 

Zinerehloride,_--3......---..--- 108. 6 Darkenedis.<2¢ 2 & 12 | Severely molded; no decay. 
No change at 24 months. 

Lor ee oe? TGS, CORT CA Se Say te ARE ONY 12 | Severely molded; somewhat 
decayed. 

Zine silicofluoride-_____________- 32.9 None yy of 9 3 peed 11 | Somewhat molded; nc de-. 
, cay. No change at 22 
months. 

itn SS SS iy aT (ae a LOE A= <5 2pREN TG) Te 11 | Somewhat molded; no de- 
cay. Somewhat decayed 
at 22 months. 

[Gli OE ee SO: Ore, [2222 GOS a ets cee 6 | Slightly molded. 

1) 0 Ue eh eee eee DOL Da) | sane COSTE aot 11 | Slightly molded; no decay. 

; Slightly decayed at 22 
months. 

iv Cj. olga yale ee 104.5 S }____- Goes 202 4 ook «J 11 | Slightly molded; consider- 

: ably decayed. No change 
at 22 months. 
_ Zing sulphate, ‘ce. pz-.-..-<.-.-- 95. 7 Slightly brown_-______- 13 | Severely molded; no decay. 
Zinc sulphocarbolate___________ 57.4 IN‘onemaet NBs oe ce hE. 11 | Severely molded; consider- 
ably decayed. 
Lie be eae eee LOG: 2s Se luss22 GOebe? : 8b ee Oa 11 | No appreciable mold or de- 


eay. Slightly molded and 
decayed at 22 months. 


1 Unless otherwise indicated, the chemicals were of ‘‘technical’”’ quality. 

2 Solutions applied warm or hot. 

3 Saturated solution with some chemical in suspension. 

4 Diluted with 95 per cent alcohol. 

5 Volatile oil of Monarda fistulosa, yielding carvacrol. Prepared and donated by the department of 
chemistry, University of Wisconsin (oil No. 5). 

6 The emulsions of oils No. 1, 2, 3, 4, and 5 were made in the following manner, using rosin size of about 
the same concentration asin 15. ‘The rosin size was not cleared by use of excess sodium hydroxide. The 
oils added in small amounts were shaken with an equal volume of the emulsifying agent, then diluted to 

.. 15,000 c. c. with water. The amounts of oil and emulsifying agent used were: No. 1 with equal volume of 

rosin size, slightly alkaline. No. 2 with equal volume of rosin size, plus 0.1 volume of saponin solution. 
No. 3 with equal volume of rosin size, plus 0.4 volume of saponin solution. No. 4 with equal volume of 
rosin size. No. 5 with equal volume of rosin size, plus 0.1 volume of saponin solution. 

7 Phenol portion of 5 (oil No. 4). 

8 Nonphenol portion of 5 (oil No. 1). 

§ The undissolved portion of solid chemical was put on surface of pulp. 

_ 10'This chemical appears to attack the fiber and weaken the pulp. It gives a pinkish cast to the pulp. 

11 Solution made up in zinc-lined vessel, and lead precipitated out. 

12 Appears to weaken the pulp. 

12 On exposure to air and light solution forms red mercuric oxide. 

14 Strong solution made up in 95 per cent alcohol and diluted to the desired concentration with water. 

15 The emulsions of nitrobenzene and orthonitrotoluene were made by shaking with the oils an equal 
volume of rosin size, of about the same concentration used in the paper mill, which had been previously 
cleared by adding NaOH solution. The oils were added in small amounts to the size solution and well 
shaken before adding the next portion. This gives an emulsion with the oils as the discontinuous phase 
and water as the continuous phase. 

- 16 First sprayed with salol, then with 0.5 per cent sodium carbonate. 

17 Volatile oil of Monarda punctata, yielding thymol. Prepared and donated by the department of 
chemistry, University of Wisconsin (oil No. 2). 

18 Nonphenol portion of 17 (oil No. 3). 


44 BULLETIN 1298, U. S. DEPARTMENT OF AGRICULTURE 


REQUIREMENTS A PRESERVATIVE MUST MEET TO BE SUITABLE 


In the selection of a preservative, several characteristics besides 
effectiveness as an antiseptic must be given consideration, such as: 

1. Poisonous properties. 

2. Chemical discoloration produced in the pulp. 

3. Odor. 

4. Solubility in cold water. 

5. In the case of oils, ease of emulsification. 

6. Cheapness and availability. 

Some substances which are quite efficient as antiseptics must nec- 
essarily be ruled out of commercial use, because in the handling of 
either the solutions or the sprayed pulp sufficient quantities of the 
poison might be absorbed through the skin to impair the health of 
the worker. Likewise, violent poisons which might accidentally 
enter the body through the mouth must be avoided in order to protect 
the consumer. Examples of such dangerous substances are mercuric 
chloride (corrosive sublimate), sodium arsenate, and sodium cyanide. 

Some highly efficient antiseptics produce objectionable discolora- 


tions in the treated pulp, which are due either to the color of the — | 


chemical or to caustic or other action on the wood fiber. All of the 
alkalies produce browning, the depth of which depends on the sub- 
stance used and the concentration of the solution employed. For 
instance, borax produces a slight browning which is not objectionable, 
‘whereas both sodium carbonate and sodium bicarbonate will so dis- 
tinctly darken the pulp as to make it unfit for commercial use unless 
it is to be piswebied later. Sodium dichromate, likewise, ultimately 
browns the pulp to a considerable degree if applied at a rate of 20 
pounds or more per ton. At some mills there might be objection to — 
this darkening, but at the mill where the tests were made there 
seemed to be no objection to it. . Sodium dinitrophenolate 1s appar- 
ently not adapted to commercial use on ground wood in amounts 
larger than 2 pounds per ton. Even at 0.9 pound per ton the yellow 
tint rodent: though it readily leaves the pulp on washing, is dis- 
tinctly noticeable. : 

None of the substances recommended hereafter give rise to objec- 
tionable odors, but the opposite is true of some of the chemicals 
experimented with. , 

Solubility in cold water is a very important property, as in most 
cases the chemicals are most easily applied in the form of water 
solutions. : 

Oils are preferably to be emulsified in order to secure the proper 
dilution. The readiness with which they emulsify is an important 
factor in their application. the 

Of course, price and availability will have much to do with the 
selection of th 
must justify the cost of it. How much the treatment will cost 
depends largely on how much of the chemical is necessary to treat a — 
unit of pulp effectively. 


CHEMICALS GIVING MOST FAVORABLE RESULTS 


Of the chemicals tried, six gave favorable results in preventing 
mold and decay and also met other requirements sufficiently well to — 
warrant their commercial consideration. Brief information concern- 
ing these follows. : 


e chemical to use. The results from the treatment — 


CONTROL OF DECAY IN PULP AND PULP WOOD — 4b 


Borax is a white substance, 5.3 per cent soluble in water at 70° F. 
and 7.4 per cent at 86° F. It is nonpoisonous and therefore safe 
for workmen to handle. It slightly darkens the pulp but not to an 
objectionable degree. About 17 pounds of ground wood and 5 pounds 
of sulphite were treated with borax at the laboratory; 450 pounds 
of ground wood were treated at the mills. The borax treatments 
at the laboratory held the pulp in good condition (with slight mold- 
ing in a few cases) for six to eight months. Tests lasting for from 
13 to 24 months gave quite satisfactory results. (See Pl. XIV, fig. 
1.) The mill tests, with 54 to 84 pounds of chemical per ton dripped 
on the pulp back of the press rolls, were not so favorable, the pulp 
having molded considerably within six months. , 

Borve acid is 4.8 per cent soluble in water at 68° F’. and is colorless 
in solution. It is nonpoisonous and safe to use, but more expensive 
than borax. It gives a slight pinkish-brown color to ground wood. 
About 10 pounds of ground wood and 4 pounds of sulphite were 
treated with boric acid at the laboratory; 160 pounds of ground wood 
were treated at the mill. After six months, the pulp was somewhat 
molded but in fairly good condition. After 12 to 13 months it was 
still in fair condition, with no active decay present. 

‘Cymene-naphthalene mixture.—Spruce turpentine (crude cymene) 
is a reddish-brown liquid by-product of the sulphite mill. Naph- 
thalene is the white substance used commonly as moth balls. It is 
33% per cent soluble in cymene at 122° F. 

Pulp treated with naphthalene alone remained in good condition 
directly. under the crystals, but became badly molded elsewhere. 
(Pl. XV, fig. 1.) With cymene alone, severe molding occurred. 
(Pl. XV, fig. 2.) About 150 pounds of ground-wood pulp were 
treated with mixtures of equal parts by weight of the two substances. 
Four pounds per ton of this mixture preserved the pulp perfectly 
for 10 months. The writers advise the use of 114 pounds of naph- 
thalene dissolved in 6 pounds of cymene to a ton of dry pulp. To 
facilitate uniform application, the chemicals should be emulsified 
sg a aid of rosin soap and diluted with water. (Pl. XV, figs. 3 
and 4. 

Sodium fluoride is a white salt 4.3 per cent soluble in water at 
64° F. It is perfectly safe for workmen to handle and causes no 
chemical discoloration of the pulp. At the laboratory about 11 
eon each of ground wood and sulphite were treated with sodium 

uoride; at the mills 735 pounds of ground wood were so treated. 
The mill application of 18 to 28 pounds of chemical per ton gave 
somewhat variable results up to 16 months, the pulp in some cases 
being only slightly blue-black molded and in others rather badly so. 
It was, however, free from decay. Thirty-seven pounds per ton 
_ preserved the Pulp very well, permitting only slight molding after 16 
_ months. Part of the pulp at the mill was somewhat molded after 
six months, but not seriously. 

Sodium dinitrophenolate is a yellow salt producing a yellow solution. 
It is approximately 2.4 per cent soluble in water at 59° F. Although 
in its concentrated form it is considered an industrial poison, it is 
thought that in the dilution hereinafter recommended it will not 
injure the health of workmen, provided reasonable care be exercised. 
In the lower concentrations it colors the pulp slightly yellow, and in 
the higher distinctly so. This color readily washes out, but the 


46 BULLETIN 1298, U. S. DEPARTMENT OF AGRICULTURE 


washed pulp may be left somewhat darker than normal. About 14 
pounds of ground wood and 22 pounds of sulphite were treated with 
sodium dinitrophenolate at the laboratory; 430 pounds of ground 
wood were treated at the mill. From 1 to 2 pounds of chemical per 
ton preserved the pulp from decay for periods up to 16 months, but 
did not prevent all molding. Up to six months these concentrations 
proved highly efficient. On sulphite, 3 pounds per ton almost 
perfectly preserved the pulp for 24 months. Concentrations of 4 
pounds and higher are somewhat more effective, but they color the 
pulp rather too yellow. 

Sodium dichromate is a reddish-brown substance readily soluble in 
cold water, yielding an orange-yellow solution. When applied at the 
rate of about 30 pounds per ton it immediately stains the pulp a 
slight yellow, and the discoloration, on standing, becomes brownish, 
darkening the pulp somewhat. Although classed as a poison, 
sodium dichromate is not considered dangerous to handle. About 
45 pounds of ground wood and 11 pounds of sulphite were treated 
with this preservative at the laboratory; 230 pounds of ground wood 
were treated at the mills. The addition of 8 pounds of chemical 
per ton at one mill preserved the pulp for seven months. From 14 to 
28 nae of chemical per ton at another mill permitted only shght 
molding in 16 months. The laboratory results were not so good. 
Ten pounds per ton preserved the pulp for three months but failed 
in six months. (Pl. XIV, fig. 2.) From 20 to 33 pounds per ton 
kept it in rather good condition for 6 months, but failed in 13 
months. The sulphite pulp held up better than ground wood. 


COMMENTS ON OTHER CHEMICALS Br 


Beta naphthol (1 pound per ton) failed, under a severe laborato 
test, to preserve ground wood for as long as 13 months, but 6 poun 
per ton almost perfectly preserved sulphite pulp for 2 years. Because 
this substance is but slightly soluble in water, it was applied in sus- 
pension. Dusting the dry chemical on the pulp may prove a better 
procedure. 

Copper acetate gave unfavorable results when used at the rate of 10 
pounds per ton. Thirty-seven pounds per ton gave rather good 
results. It browns the pulp considerably. 

Copper acetoarsenite ane green) gave efficient protection when 
used at a rate of 7 pounds per ton. It is too poisonous to handle, 
however, and gives a deep green surface discoloration to the pulp. 

Copper sulphate at a rate of 78 pounds per ton gave considerable 
protection. 

Dichlorobenzol was highly effective in the excessive amounts em- 
ployed, and further tests should be made at lower concentrations. 
It was used in the form of a crude oil, but dilute emulsions in water 
probably can be easily made. It is volatile, and the odors are oppres- 
sive in a closed space but not particularly poisonous. It is used in the 
crystalline form as a very effective insecticide in herbaria, ete. 


Dinitrochlorobenzol proved very effective when applied at the rate 


of 6 pounds per ton, but on account of its highly poisonous properties 
it can not be recommended as a pulp preservative. 

Lysol (96 pounds per ton) protected the pulp from decay but per- 
mitted severe molding. : | 


ee ae a 


ee ee ee 


CONTROL OF DECAY IN PULP AND PULP WOOD 47 


Magnesium silicofluoride (53 pounds per ton) and zine silicofluoride 
(33 pounds per ton) gave a considerable measure of protection, but 
| ‘sire am data are needed in regard to their possible action in weakening 

the pulp. 
Sodium arsenate (43 pounds per ton) and sodium arsenite (102 pounds 
_per ton) protected the pulp to a considerable extent, but on account of 
their highly poisonous character can not be recommended. 

Sodium bicarbonate, ordinary baking soda, browned the pulp as 
did sodium carbonate, and also apparently softened it. 

Sodium carbonate, a white salt readily soluble in cold water, is a 
fairly strong alkali. It was found to brown the pulp to a marked 
degree. The discoloration readily bleaches out of sulphite pulp, 
without increased bleach consumption, but the pulp is somewhat 
softened by the action of the alkali. 

Thymol gave considerable protection in some cases, but the results 
were too erratic to warrant recommendation until further and more 
uniformly favorable data are obtained. The mill tests (none were 
made at the laboratory) of the two distillates from the thymol-yielding 
plant Monarda punctata resulted very favorably. However, large 
quantities of these distillates are not available at present. 

Mill tests of the three distillates from the carvacrol-yielding plant 
Monarda fistulosa also gave favorable results. Production of these 
distillates on a commercial scale would perhaps bring their cost low 
enough to permit their use. 

Zine chloride (108 pounds per ton) gave very favorable results in 
preserving the pulp against decay but permitted heavy infections of 
speckled pray mold. 

The following preservatives, in addition to those listed in Table 13, 
have for various reasons proved unsatisfactory under the severe condi- 
tions imposed in the laboratory tests: Calcium hydrate, copper 
oleate, formaldehyde, formic acid, mercuric chloride, naphthalene 
(dry and in alcoholic solution), rongalite, sodium bifluoride, bleach 
liquor, and fresh and waste sulphite liquor. (Pl. XIV, fig. 3.) 


PREVALENCE OF VARIOUS FUNGI ON TREATED PULP 


The molds most commonly found on the experimental pulp, listed 
in the order of their frequency of occurrence, were those respectively 
roducing neutral gray, pink, purple, and yellow spots or blotches. 
eutral gray discolorations were attributable to any one of several 
molds that have brown mycelia. Species of Penicillium and Fusa- 
rium produced discolorations pink to purple in tint, and some species 
of Trichoderma caused yellow areas. 
Gray discolorations were found quite generally throughout the 
- packs. Certain molds were more frequently found on the outer laps 
_ and along the edges and folds than elsewhere. The ammonium salts, 
sodium chloride, and sulphite liquors seemed to stimulate all kinds 
of fungous growth. Pulp which had been sprayed with copper 
nitrate, lead acetate,t and zine chloride was found covered with 
numerous minute gray specks. 
_ Mercuric chloride permitted the light-colored molds, Penicillium 
and Trichoderma especially to develop. 


_ 4 When prepared in zinc-lined vessels, this salt was largely changed over to zire acetate. 


48 BULLETIN 1298, U. S. DEPARTMENT OF AGRICULTURE 


Alphanaphtylamine, aluminum fluoride, aluminum sulphate, potas- 
sium bromate, potassium permanganate, salol, sodium aluminate, 
and sodium sulphocarbolate seemed to check all the molds except 
those causing the neutral gray discolorations, but they did not 
control the wood-destroying fanwic | 

Potassium permanganate colored the pulp a dark brown, but the 
wood-destroying fungi bleached out this color. 


PRESERVATIVES RECOMMENDED FOR MILL APPLICATION 


Of the preservatives reported upon, sodium fluoride shows the 
highest antiseptic effectiveness and the fewest objectionable features 
for mill application. Cost is the main objection to it. Borax is a 
close second. 

Boric (boracic) acid is equal or somewhat superior to borax, but 
its greater cost throws it out of competition. | 

A combination of naphthalene an am in the proportions rec- 
ommended above, promises to be nearly as effective as sodium fluo- 
ride, and is very much cheaper. | 2 

Sodium dinitrophenolate, applied at the rate of 2 pounds per ton, 
appears very promising. In antiseptic efficiency it is equal to any- 
thing tried, but the yellowish chemical discoloration it causes may 
render the pulp objectionable for some purposes. ‘This stain, how- 
ever, readily washes out, although it may leave the pulp somewhat 
browner than normal. 


Sodium dichromate did not seem to give quite as good results as 


the four substances just mentioned. Its antiseptic efficiency varied — 
rather too widely in the tests, and its tendency toward browning of 
the pulp was rather marked, particularly when applied at a rate of 
32 pounds per ton. : 
Ciccorvative solutions should be applied at the press roll, in which 
case the retention is about 70 per cent for a 5 per cent solution. The 
loss of chemical in the white water must be compensated for in order 
to get the necessary actual concentration in the pulp. There is no 
danger of the treated pulp sticking to the rolls. *s 
Preservative solutions can not be effectively applied to pulp in 
storage, either before or after infection has taken place. Any 
method of dipping or spraying that would be satisfactory would not 
be poate as. feasible. It thus appears a much simpler matter to 
prevent the development of molds and decay than to stop it. | 
Aside from technical difficulties in application the deciding factor 
in the commercial use of any cloetaaaad | is its cost, and this fact has 
not been lost sight of in this investigation. 
On the assumption that the pulp normally leaves the wet machine 
one-third dry, the cost of various chemicals per ton of air-dry pulp, 
at the market prices of July 9, 1923, would be as follows: 


a 
of pulp 
Borax, 80 pounds per ton, at 514 cents per pound_____-___--__-_----__. $4. 20 
Boric acid, 80 pounds per ton, at 10 cents per pound_-_-_-------------_- 8. 00 


Crude cymene, 6 pounds per ton, at 614 cents per pound, and crude naph- 6 


thalene, 1144 pounds per ton, at 3 cents per pound_________-___--__-- . 42 
Sodium fluoride, 48 pounds per ton, at 834 cents per pound_______-___. 4. 20 


Sodium dinitrophenolate, 2 pounds per ton, at 40 cents per pound (for 
dinitrophenol) : LY 
Sodium dichromate, 16 pounds per ton, at 8 cents per pound__-__.--_-_ 1. 28 


CONTROL OF DECAY IN PULP AND PULP WOOD 49 


In some cases the amount of chemical recommended above is less 
than that indicated in Table 13 as the effective quantity, but it 
should be borne in mind that there was a much greater loss of chemical 
from diffusion in the laboratory tests than would obtain in industrial 
practice. ie 

In order to gain some idea of what additional expense the mills 
would consider practical for safeguarding pulp to be stored for any 
considerable time, a number of questionnaires were sent out in May, 
1921. Twenty-three replies were received. The estimates of the 
nine companies submitting definite figures varied from $1.25 to $6 
per ton, the average for maximum figures being about $3.50. On 
this basis only three of the preservatives suggested herein would be 
available, namely, cymene-naphthalene mixture, sodium dinitro- 
phenolate, and sodium dichromate; but improved methods of apply. 
ing the preservatives, so that a greater amount will be retained by 
the pulp, may hereafter permit the use of lower concentrations and 
thus make possible the use of some of the more expensive chemicals. 


SUMMARY 

An extensive survey of storage conditions at pulp and paper mills 
indicates that serious losses occur both in stored wood and in pulp, 
especially ground wood. Storage conditions in the woods and at 
the mill can be improved so as to reduce these losses. 

The deterioration of wood and wood pulp is due mainly to fungi. 
For practical purposes these fungi may be divided into two general 
groups—molds and wood-destroying organisms. The former dis- 
color the pulp but do not appreciably affect its strength; the latter 
produce true decay. 

The character of the wood available for pulping is an important 
factor in its storage. Pulp wood usually consists of the less dur- 
able species. The length of storage, the time of cutting, the removal 
of bark, the presence of insects, methods of piling, and general sani- 
tation about the yards are all conditions which affect the life of wood. 
The prevailing methods of storing wood are discussed in detail, and 
the desirability of segregating infected from sound wood and of 
Pee all wood in rotation is emphasized. 

n order to demonstrate the difficulties met with and the large 
losses sustained in the use of decayed wood, a considerable amount 
of wood in various stages of decay was pulped by the mechanical, 
sulphite, and soda processes. The grinder runs on (spruce) wood . 
which had been stored for three years under unfavorable conditions 
demonstrated a loss in yield of 16 per cent, based on weight of oven- 
dry barked wood. ‘The resulting pulp was freer, contained a larger 
number of shives, and was decided y darker in color than pulp 
made from sound wood. In the manufacture of chemical pulps, 
chipping losses ranged as high as 17 per cent for badly decayed 
material as compared with 4.4 per cent for sound material. The 


NotrEe.—Final conclusions as to the value of decayed wood, in general, for chemical pulp should not be 
drawn from the specific data presented in this bulletin. The value of decayed wood for sulphite pulp is 
closely associated with the chemical action of the wood-destroying organisms, and these organisms vary 
widely in their method of attack. Further investigations, under way at the Forest Products Labora- 
tory, indicate already that some types of rot tend to reduce the value of wood for sulphite pulp less than 
the superficial appearance of the wood might suggest. 


523°—25t 4 


50 BULLETIN 1298, U. S. DEPARTMENT OF AGRICULTURE 


yields of screened sulphite pulp were not, as a rule, much lower 
than the yield from sound spruce. These yields, however, being 
figured on an oven-dry weight basis for both the wood and the pulp, 
do not represent the actual loss. If the yields per cord could haye 
_been determined, a distinct lowering with increased decay would 
have been demonstrated Soda cooks required more chemical for 
decayed wood than for sound, since the portion that had decayed 
was more readily soluble in the cooking liquor. When the pulp was 
undercooked, screenings were about 17 per cent, with a yield of only 
32 per cent. In these experiments the chemical pulps from decayed 
woods were lower in strength, showed less endurance against folding, 
and were exceptionally dirty. . 
Chemical analyses of various sound and decayed woods explain 
the losses that occur through decay. The principal changes are 
marked increases in constituents soluble in hot and cold water and 
in alkali, indicating changes in the character of the cellulose from a 
resistant to a less stable form. The lignin does not appear to be 
destroyed in any appreciable amount. In the case of pulp (spruce, 
sulphite) made from decayed wood, decay is likewise reflected in 
increased solubility in water and NaOH and lessened stability of the 
cellulose. It is thus evident that a qualitative parallelism exists 
sadder decayed wood and the mechanical and sulphite pulps made 
rom it. ¥ 
In present commercial practice Pup is usually stored in large 
piles in the open or placed in closed unheated sheds or in the base- 
ments of mills. As a result of manufacturing conditions, ground 
wood is frequently stored for 6 to 12 months, or even longer. Chars. 
cal pulps are, for the greater part, converted immediately, or within 
a few months. Deterioration during storage is often severe, partic- 
ularly with ground wood, and is due both to molds and to wood- 
destroying fungi. Molds, though not affecting the strength of the 
pulp, discolor it and frequently bind together the Pee articles so 
that the molded spots or areas do not beat up well, and a lumpy, 
speckled paper results. Wood destroyers decrease the strength of 
the wood fibers and render them so brittle that they break into short 
lengths in the beater, with the result that much of the pulp is lost 
in the white water and the manufactured paper has little strength. 
The combined action of molds and wood-destroying tung thus results 
in the production of paper of very poor color and quality. Ba St 
In order to combat deterioration of pulp during storage, careful 
attention must be given to the elimination of sources of infection. 
Pulp may become infected with molds either through the spores which 
abound in the air and in the water used in manufacturing processes, 
or by direct contact of moldy with clean pulp. Infection by wood 
destroyers more often occurs through contact with infected pulp or 
wood, but it may also occur through secondary spores produced 
on the fungus mycelium, or through spores of the more common 
type, produced on the fruit bodies which develop on wood in the 
form of conchs, brackets, toadstools, mushrooms, leathery incrusta- 
tions, etc. Humus soil also appears to be an important source of 
infection for both molds and wood-destroying fungi. This may be 
carried about on the workmen’s clothing or shoes. ei ately 
The physical characteristics of pulp which has decayed in storage 
are similar to those of pulp made from badly decayed wood. Such — 


CONTROL OF DECAY IN PULP AND PULP WOOD 51 


ulp is much freer than sound pulp, is brash and _ brittle, foams 

badly: and tends to stick to the couch and press rolls. The paper 
made from it is considerably darker and much weaker than that 
from sound, and only one-tenth as resistant to ink penetration. 
Ground wood made from decayed wood deteriorates more rapidly 
during storage than that made from sound wood, in spite of the 
apparent destruction of most of the fungi in the original wood during 
the grinding process. 

e most feasible method of controlling deterioration in pulp 
during storage, in addition to the adoption of the precautions against 
infection already indicated, is to introduce an antiseptic into the 
pulp on the wet machine. One hundred and twelve chemicals were 
tested for this purpose. About 3,000 small ground-wood laps and 
1,400 sulphite laps were treated at the laboratory, and about 7,200 

ounds of ground-wood pulp at the mill. The chemicals that best 

ed the requirements for a preservative were borax, boric acid, a 
solution of naphthalene in crude cymene, sodium fluoride, sodium 
dinitrophenolate, and sodium dichromate. 

In the appendix will be found a record of studies, more compre- 
_ hensive than any hitherto undertaken, of the fungi which inhabit 
pulp. Through these studies it was determined for the first time 
that the principal chemical damage to pulp is attributable to the 
hymenomycete fungi rather than to any of the molds. Sixteen 
hymenomycetes were isolated, but only one was completely identified, 
owing to the great difficulty of developing charactertistic fruit 
bodies in culture. The various fungi are described, and in addition 
to the morphological grouping there is presented a new scheme of 
‘classification of these fungi which is based on the color reactions of 
pulp infected by them. 

In the appendix is also reported the first extensive investigation 
of the chemical action of fungi on ground-wood pulp. 


APPENDIX 


STUDIES OF SPECIFIC FUNGI THAT DETERIORATE WOOD PULP 


Up to the present no careful systematic study of pulp-inhabiting 
fungi has been made. As far as is known by the writers, investigators 
in the past have ignored the hymenomycetes entirely, owing to the 
fact that before this study was undertaken no one used cultural 
methods in studying pulp fungi. The hymenomycetes can not often 
be detected by a mere examination of the pulp. Areas infected 
with them are commonly overrun by molds, which accounts for the 
fact that certain authors attribute serious decay of pulp to some of 
the molds. | 

In the course of the investigation a large number of fungi have 
been isolated from pulp and wood. In this appendix are presented 
the cultural characters of the fungi isolated, together with a classi- 
fication i these fungi based on the color changes which they produce 
in the pulp. ) | 

Many of the organisms were grown on ground-wood pulp in order 

to determine their specific effect on the fiber. In general, it was 
found that the loss in weight produced by molds was slight, the 
greatest loss being 3.2 per cent in 12 months. Wood-destroyin 
ungi (hymenomycetes), on the other hand, produced losses as igh 
as 49.5 per cent within the same period. Analyses of the various 
samples showed that the effect of molds on the chemical constitution 
of the fiber was likewise slight, but that wood-destroying fungi 
produced very marked changes in this respect also. 


WORK OF PRIOR INVESTIGATORS 


Cellulose fermentation is the outstanding factor in the decay of 
both wood and pulp. It is known to be caused by certain hymeno- 
mycetes (among which are wood-destroying fungi), to a lesser extent 
by some of the fungi commonly called molds, and, more rarely, by 
certain groups of bacteria. The relative destructiveness of the first 
two groups, so far as concerns pulp in particular, has only lately 
been recognized—although for 70 years or more the general subject 
of cellulose fermentation has repeatedly attracted the attention of 
investigators. In 1850 Mitscherlich (17) first attributed the fermen- 
tation of cellulose to microorganisms. Workers immediately fol- 
lowing Mitscherlich interested themselves not in the organisms 
causing cellulose fermentation, but rather in the products these 
organisms formed in the fermentation processes. After about 25 

ears investigators became interested in the organisms themselves, 
but more attention was then given to bacteria than to fungi. Ahi, 

To Van Iterson (13) belongs the credit for the first systematic — 
study, as late as 1904, of cellulose fermentation induced by fungi. — 
His method was the following: Two sterile sheets of pure filter paper 
were placed in a Petri dish and moistened with tap water in which 


52 


CONTROL OF DECAY IN PULP AND PULP WOOD 53 


ammonium nitrate and monobasic potassium phosphate were dis- 
solved in the ratio 100: 0.05: 0.50; for inoculation, soil or humus 
was used, or the dishes were exposed to the air. The species were 
then separated on malt gelatin and tested for their cellulose-ferment- 
ing ability. Many active cellulose destroyers were thus obtained. 
In order to determine the abundance of mold spores in the air, Van 
Iterson exposed in the garden for 12 hours a Petri dish having a 
surface of 275 square centimeters and containing moistened filter 
paper. One hundred and fifty-two mold colonies developed, repre- 
senting 35 different species. Fifteen cellulose destroyers in all were 
isolated and described in the course of this first investigation. 

McBeth and Scales (/6) list 16 different species as being able to 
destroy cellulose more or less rapidly, and point out that fungi are 
not so largely confined to acid soils as is generally believed. They 
hold that cellulose destruction in soil is largely due to the work of 
filamentous fungi. 

Hartig (9) and a large number of other workers have recognized 
the part that the higher fungi, the hymenomycetes, which we com- 
ftianiky call wood-destroying fungi, play in the destruction of cellulose 
and other constituents of wood. 

‘Of the fungi which infect woed pulp, however, very few investiga- 
tions have heretofore been made, although notes concerning the 
deterioration of paper date back to the early part of the eighteenth 
century. At that time, and until recently, the spotting of paper was 
attributed to the work of larve. 

In 1896 Klemm in Germany (14), published a short paper in which 
it is stated that the most common, as well as the most detrimental, 
of pulp-inhabiting fungi is Rhynchosphaerra sp. This mold is re- 
ported as appearing either as brown or dark-green spots with dark 


 eenters from which radiate delicate branched threads, or as numerous 


spots grouped together in blotches or in parallel lines of a gray color. 

lemm attributed the uneven distribution to the mode of infection. 
This fungus, he showed, is propagated by two kinds of spores— 
ascospores, produced in asci (sacs) in perithecia, minute flask-shaped 
bodies with long narrow necks; and dark colored cells (chlamydos- 
pore? produced in chains in the mycelium. Chlamydospores are by 

ar the more common. ‘The perithecia were seen only occasionally 

on the surface of old pulp. 

Klemm pointed out, also, that some organisms, although very 
destructive, are difficult to detect because they produce no discolora- 
tion. Pulp thus infected produces a paper which may rapidly 
become weak and brittle. Tt is quite siden that these fungi are 
the true wood destroyers, hymenomycetes, but Klemm did not seem 
to recognize them as such. He noted that Stachybotrys atra Cda., a 
“‘sooty’’ mold, is frequently present in large quantities, and that its 
spores cause a perceptible darkening of the pulp. Mention is made 
also of a mold, found on old pulp, which forms small, black, globe- 
like bodies surrounded by a yellow or brown spot. The conclusion 
is reached, however, that both this mold and Stachybotrys atra are 
relatively harmless, since their mycelia do not pierce, but only inter- 
lace, the wood fibers. 

Barnes (2), while working as chemist for a large paper mill, observed 
mechanical wood pulp which was seriously damaged by rot—some 
of it rendered 20 to 25 per cent soluble in water and utterly ruined. 


54 BULLETIN 1298, U. S. DEPARTMENT OF AGRICULTURE 


During three years many shipments of Scandinavian and Canadian 
pulps received were more or less damaged by “‘fungoid growth and — 
rot.’’ Microscopic examinations of the pulps were made, in an 
attempt to determine the cause of the deterioration. Barnes stated 
that the chief effect was a blackish discoloration produced by a 
species of Cladosporium, which he held responsible in most cases for 
ai systematic decay of ground-wood pulp. There is shown a rough 
drawing of a ‘“‘type of white fungus growing on the surface of the 
sheets in the interior of a bale of mechanical pulp.” This was 
probably a hymenomycete. He considered the “fission fungi’’ 
(evidently, to judge from his figure, Penicillium sp.) to be the cause 
of the rapid decay of external parts of laps already infected with 
Cladosporium sp. He noted molds producing brick-red, yellow, and 
violet pulp, but remarks that they had very little ‘‘ tendering”’ effect 
upon the pulp. In one series of tests various conspicuous spots were 
marked on mah laps with a violet pencil; the marked laps were then 
piled in a compact stack and surrounded by moist sound ground 
wood. At the end of the six weeks it was found that all spots, 
including the “‘grayish markings due to reaction of iron and tannin 
bodies,’”’ had increased in size, and that the white branching fungus 
had grown far into the bale. 

Sée (24) has made a rather thorough study of the fungi found on 
paper. He isolated 27 species belonging to 16 genera. As to their 
source, he states that the spores of the fungi are in the paper when it 
is made, but apparently he made no tests to substantiate his asser- 
tion. The assumption is based upon the presence of the same species 
on both paper and pulp. 

Moreau (/8) reports a very much blackened condition of imported 
pulp, supposedly due to the presence of a sphaeriaceous fungus. He 
advised that antiseptic measures be taken before shipping, because 
the presence of large quantities of the fungus would necessitate the 
use of excessive amounts of hypochlorite for bleaching. 

In the review (4) of the work of Beadle and Stevens the most 
interesting fact, from the present standpoint, to be developed is that 
blue stain, caused by Ceratostomella spp., sometimes gives rise to 
trouble in paper making. The authors are inclined to believe that 
these species have a weakening effect upon mechanical pulp. Their 
spores are produced in long, beaked perithecia at the ends of logs or 
in cracks and holes. 

The only hymenomycetes reported in the literature as inhabitin 
pulp are Paaillus panuoides Fr. and Trametes serialis F'r., observe 
by Von Schrenk at Glens Falls, N. Y. (21), whereas in the present 
investigation it has been conclusively shown not only that the 
hymenomycetes are present but also that they are responsible for 
the greatest amount of damage to pulp. It seems probable that had 
careful culture experiments been run, the previous investigators 
would have found hymenomycetes mixed with such molds as 
Rhynchosphaeria and Cladosporium, which they reported responsible 
for pulp decay. Without isolation studies it would have been easy 
indeed to mistake the more evident molds for the really destructive 
hymenomycetes. t 


CONTROL OF DECAY IN PULP AND PULP WOOD 55 
MATERIALS AND METHODS EMPLOYED 


In tne study here reported, fungi were isolated from 18 samples 
- of ground wood, 5 samples of sulphite pulp, 1 sample of soda pulp, 
8 pulp logs, 7 boards taken from pulp sheds, 1 sample of white water, 
and 4 samples of river water. Although no attempt was made to 
obtain in pure culture all of the fungi that are in any way responsible 
for the deterioration of wood pulp, the writers nevertheless feel con- 
fident that they have isolated all of the more serious enemies common 
to pulp in the localities from which pulp samples were received. 
These samples, either in single laps or in larger amounts up to ap- 

roximately half a ton, were submitted from mills in New York, 
Sane basin Minnesota, and Canada. Other samples of water were 
plated out, but since they yielded neither cellulose-dissolving molds 
nor hymenomycetes, no further study of them was made, nor were 
the cultures which they produced retained. 

All culture work was performed in a culture case kept sterile by 
careful washing out with mercuric chloride solution (1:1000) before 
each using. 

For general purposes, plain malt agar, made up according to the 
following formula, was found to be a very favorable medium: 


ennai ee Fife ete oe cubic centimeters__ 1, 000 
omamien spiain malt extract. 22.042 .- 420-42 se ete grams__ 25 
Agar-agar, powdered or Bacto (acidity not adjusted) ______-_-_-- doe 2s 15 


Approximately 20 cubic centimeters were put in each test tube. 
After sterilization the medium was poured from the tubes into sterile 
Petri dishes, 3 or 4 drops of 5 per cent lactic acid having been added 
to half the tubes just prior to pouring. Both plain and acidified 
plates were then used in plating out the pulp samples. In special 
cases, in which the fungus could not be made to grow upon the plain 
malt medium, potato, carrot, bean, prune, and oatmeal agars were 
tried. In no case, however, were cultures obtained on these special 
media when they would not grow on the plain malt agar. For 
. making cultures from river water, McBeth and Scale’s cellulose agar 
was used. 

Characteristic spots on the pulp were selected. In the compara- 
tively few cases in which suriface spores were present, a platinum 
loop full of sterile water was brought into contact and the adherent 
spores were transferred to a sterile tube containing about 2 cubic 
centimeters of distilled water. After a thorough shaking of this first 
tube further dilutions were made. Then a few drops of the spore 
eo were poured upon plain malt and acidified plates, and 
each plate was shaken gently until the entire surface was covered 
with a thin layer of the water. The plates were then incubated at 
25 to 30° C. for the necessary period, which varies considerably 
with the various species of fungi. If the colonies on the plates were 
fairly uniform and sufficiently scattered, some of them were trans- 
ferred to malt slants before any of them had sporulated. If mixed cul- 
tures were obtained, as was usually the case, the best plates were held 
until the desired fungus sporulated, when more plates would be made 
from it and the process repeated until pure cultures were obtained. 

On the majority of the pulp samples, however, the spots were 
apparently pigmented or bleached areas with no superficial spores, 
and the process above described was not applicable. In such in- 


56 BULLETIN 1298, U. §, DEPARTMENT OF AGRICULTURE 


stances the more isolated spots were selected. The outer layers of 
the pulp were carefully folded back with a sterile needle, and some 
of the infected pulp from the interior of the sheet was transferred to 
plain malt and acidified plates. Usually three of each kind of plates 
were inoculated, but when the infection of the pulp was unusually © 


heavy many more were used. If the spots were produced by molds, — 


pare — cultures were made as soon as the fungus sporulated. — 
he hymenomycetes were much more difficult to isolate. The 
plates were observed frequently, and as soon as the transfer grew 
sufficiently other plates were made from the mycelial growth around 
it. Great care was taken to avoid the mycelia of any molds which 
might be present. It is seldom indeed that a piece of pulp is infected 
with a hymenomycete without being also more or less infected with 
various molds, and vice versa. It is frequently necessary to make 
many transfers before microscopic examination shows a pure culture. 
Welcome exceptions were several hymenomycetes which produce 
oidia, chlamydospores, or basidiospores; from these, single spore 
cultures could be made almost as easily as from the molds. . 

In working for pure cultures of pulp fungi, the greatest difficult 
was caused by an overrunning of the plate by rapidly growing molds 
before other fungi could start growth. The most troublesome of 
these molds were species of Trichoderma and Mucor, which accounted 
for the loss of hundreds of plates. Some species of the former genus 
were almost invariably present and in a sporulating condition on 
deteriorating pulp. 

Although bacteria probably play some part in the decay of wood 
pulp, it is quite evident from the studies made that they are not 
as important a factor as might be expected. There are perhaps 
two good reasons why this is true. Most cellulose-dissolving bacteria — 
require (1) an abundance of moisture, and (2) a slightly alkaline 
medium. Ordinary pulp storage conditions would not satisfy the 
first condition, and ground-wood and sulphite pulps, which are 
slightly acid, do not afford the second. 


FUNGI OBSERVED 


Although molds, by which term all fungi except the hymenomycetes 
are referred to here, are more numerous and occur more frequently, 
they cause much less damage to pulp than do hymenomycetes. 
When molds are present, however, joy ancora are very likely 
to be found. | 

The most common of all the fungi observed are molds with large, 
dark-brown mycelia which interlace the wood fibers and produce 
a neutral gray or olive-black blotch in the pulp. At times the infec- 


tion spots coalesce, and large gray or blue-black areas are formed. 


Several species of fungi produce such spots, and it is impossible to 
distinguish between them except by cultural methods. Blotches 

ink to purple in hue are found less frequently. They are produced 

y species of Penicillium and Fusarium. Only rarely have these 
peels been found sporulating on the pulp. Large yellow blotches are 
frequent in occurrence, most of pacan ata indicative of some species 
of Trichoderma. Pinkish cinnamon spots are quite common, and are 
caused either by a mold or by any of several wood-destroying fungi 
(hymenomycetes). It is often difficult to distinguish between the 
two types, especially in the early stages of infection. From small — 


Bul. 1298, U. S. Dept. of Agriculture PLATE XV 


Fic. 1.—Section of small lap of ground-wood pulp treated with dry naphthalene at the rate of 
50 pounds per ton of dry pulp and stored for 1314 months in pulp shed. Note clean condition 
under flakes of naphthalene and molded condition elsewhere 

Fic. 2.—Section of commercial lap of ground-wood pulp sprayed with cymene at the rate of 
2 pounds per ton of dry pulp and stored for 10 months in pulpshed. Note the severe molding 

Fic. 3.—Section of commercial lap of ground-wood pulp sprayed with cymene and naphthalene 
mixture (50:50) at the rate of 4 pounds per ton of dry pulp. Stored for 10 months in pulp 
shed. Note perfect condition 

Fic. 4.—Section of commercial lap of ground-wood pulp stored 10 months in pulp shed. Note 
the severe molding and decay 


Bul. 1298, U. S. Dept. of Agriculture 


PLATE XVI 


CAR del 


DRAWINGS OF REPRESENTATIVE FUNGI ISOLATED FROM WoobD PULP (x 120, 
EXCEPT FIG. 4) 


Fics. 1-3.—Mycelium and chlamydospores of 
hymenomycetes 

Fic. 4—Sporangiophore of Mucor plumbeus 
X 55) 

Fic. 5.—Citromyces sp., conidiophores and 


spores 

Fic. 6.—Culture 81318-1, conidiophores and 
spores 

Fic. 7—Trichoderma sp., conidiophores and 
spores 

Fic. 8—Oidia and mycelium of Oidium sp. 

Fic. 9—Penicillium sp., conidiophores and 
spores 

Fic. 10.— Verticillium sp., conidiophores and 
spores 

Fic. 11.—Chlamydospores of Torula sp. 

Fia. 12.— Aspergillus fumigatus, conidiophores 
and spores 


Fic. 13.—A. niger, conidiophores and spores 
Fic. 14.—Penicillium sp., conidiophores and 
spores 
Fic. 15.—Gliocladium sp., conidiophores and 
spores 
Fic. 16.—Spores of Fusarium sp. 
Fic. 17.—Ffusarium sp., conidiophores and 
spores 
Fic. 18.—Chlamydospores and microconidia of 
Fusarium sp. Spores and mycelium 
Fic. 19.—Spicaria sp., conidiophores and 
spores 
Fic. 20.—Alternaria sp., conidiophores and 
spores 
Fic. 21.—Stemphylium sp., conidiophores and 
spores 


CONTROL OF DECAY IN PULP AND PULP WOOD 5Y 


round brown spots, very commonly found, a species of Alternaria 
has been isolated consistently. ot all such spots, however, are 
produced by the same fungus. | 
Several of the molds commonly inhabiting pulp produce no pig- 

ment, have a colorless mycelia, and so are evident only when ee 
-sporulate. Among these were identified species of Gliocladium, 
enicillium, Citromyces, Trichoderma, Aspergillus, and Mucor. 
Brown blotches are produced by several species of molds and by 
' some hymenomycetes. Generally speaking, the hymenomycetes 

produce areas of some shade of brown, varying from a faint pinkish 
cinnamon to a brown-black, though some produce cream-colored or 
bleached areas. The areas of pulp infected with hymenomycetes 
may be very weak. They may be much thinner than the surround- 
ing portions of the pulp oftentimes falling out entirely when the pulp 
is moved. 
Many of the cultures have not as yet been identified. Those 
isolated from pulp and water are listed as follows: 


Phycomycetes 
Mucoraceae 
Mucor plumbeus Bon. 
Mucor racemosus Fres. 
Rhizopus nigricans Ehrenb. 
Ascomycetes 
Pezrzaceae 
Peziza repanda Wahl. 
Mollisraceae 
Orbilia rubella Pers.t 
Sphaeriaceae 
Chaetomium globosum Kunze * 
Chaetomium funrcolum Cooke ! 
Basidiomycetes 
Hymenomycetes 
Agaricaceae 
Pazillus panuoides Fr. 
15 unidentified cultures, discussed hereinafter. 
Fungi imperfectt 
Sphaerroidaceae 
Cytosphora sp. 
Mucedinaceae 
Torulopsis rosea Berl. 
Ldvum sp. 
Papulospora nigra Hotson 
Trichoderma spp. (11 cultures) 
Aspergillus niger van Tiegh 
Aspergillus fumigatus Fres. (2 cultures)! 
Aspergillus flavus group (2 cultures)! 
Penicillium pinophilum Hedge. 
Penicillium purpurogenum O. Stoll + 
Penicillium brevicaule series 1 
Pencilium commune Thom 4 
Pemeillium spp. (13 cultures) 
Citromyces spp. (2 cultures)? 


Ry ACKNOWLEDGMENT.—The late Dr. E. J. Durand and Drs. A. H. Chivers, Charles Thom, and Mar- 
_ garet B, Church rendered aid in identifying these fungi. 


wtih 
py er 


58 BULLETIN 1298, U. S. DEPARTMENT OF AGRICULTURE - 


Fungi wmperfecti—Continued 

Mucedinaceae—Continued 

Gliocladium sp. 

Verticillium sp. 

Spicaria sp. 

nidentified Mucedinaceae (1 culture) 

Dematiaceae 

Torula sp. 

Thielaviopsis sp. 

Stemphylvum sp. 

Alternaria spp. (2 cultures) 

Unidentified Dematiaceae (22 cultures) 
Tuberculariaceae 

Fusarium spp. (9 cultures) 


None of the hymenomycetes which are commonly found on { 


pulp wood have been isolated from pulp although the following 
species obtained from pulp wood or from boards taken from pulp 
sheds grew when planted on pulp: Fomes roseus Fr., Lentinus lepideus 
Fr., Penophora tabacina Burt., Stereum sanguinolentum A. and S., 


Corticium galactinum Fr., and six undetermined species (cultures | 


4620-3, 4620-4, 61420-3, 61420-4, 61420-5, 61420-7). (See 
Table 16.) 


DESCRIPTION OF CULTURES OBTAINED FROM PULP AND WATER 


Cc 
PHYSOMYCETES 


MUCORACEAE 


It is probable that several species of the Mucoraceae grow on pulp, 
but for the reasons that they seem to be superficial, do not produce a 
definite discoloration, and generally do not. produce spores in numbers 
large enough to damage the pulp, little attention was given this group. 
Only three species, which occur frequently, have been aks i 

Mucor plumbeus Bon.—Mycelium submerged, hyaline; chlamy- 
dospores common, hyaline to light brown; * sporangiophores upright, 
about 1 centimeter high, branches cymose or irregular, forming a 
hoary turf in young cultures; sporangia at first gray then olive black, 


walls very finely aculeated (Pl. XVI, fig. 4); columella cylindrical or 


pyriform, with one or more tapering or blunt spines on top; spores 
obose, light brown. Isolated from soda pulp. Very common on all 
Bie of pulp. | 

Mucor racemous Fres.—Mycelium submerged, septate; chlamydo- 
spores frequent; sporangiophores upright, very short, 1 to 5 milli- 
meters, septate, branched, cymose or Tren wee sporangia small, 
white then blue-gray, walls very finely aculeated; columella hemi- 
spherical or short cylindrical; spores light brown. Isolated from 
ground wood. Common. 


Rhizopus nigricans Ehrenb.—Aerial mycelium white, aseptate, be-— 


coming dark and septate in very old cultures; rhizoids numerous; 
sporangiphores fasciculate, erect, aseptate, arising from the nodes; 
sporangia globose, olive black; columella hemisperical; spores gray 


5 Colors used in the following descriptions have, in most cases, been matched as closely as possible with 
Robert Ridgway’s Color Standards and Color Nomenclature, 1912, : 


ee ben = 


CONTROL OF DECAY IN PULP AND PULP WOOD 59 


to brown, black en masse, subglobose or irregular. Isolated from 
soda pulp and ground wood (82219-10).° Almost always present 
ondamp pulp. This is the common black bread mold, which may be 
obtained at any time by exposing a culture plate or a moist piece of 
bread to the air. 


ASCOMYCETES 


PEZIZACEAH 


Peziza repanda Wahl.—Mycelium white to cream colored, forming 
a rather thin, uneven layer over the agar, septate and colorless when 
growing in the pulp and causing no perceptible change in it; apothecia 
(fruit bodies) disk-shaped, cream-colored, 4 to 30 millimeters in 
diameter. Collected once from ground wood in a very wet place. 
Apothecia were also produced on the floor and shelves in the same 
pulp shed. 


MOLLISIACEAE 


Orbilia rubella Pers.—Apothecia small, 1 to 3 millimeters, light pink. 
_ Collected once on a very rotten pulp. Not isolated. 


SPHAERIACEAE 
Chaetomium spp.— ees hyaline, does not discolor the pulp, 
and apparently does little damage. 


Chaetomium globosum Kunze—Culture gray; perithecia rather 
- large; lateral hairs numerous, slender, slightly undulate, obscurely 
_ septate, minutely roughened, dark olive brown at base, lighter at tip; 
terminal hairs numerous, spreading and drooping, slender, aseptate, 
minutely roughened, dark olive brown with tapering yellow or hyaline 
tips, wavy. Spores olive brown, ovate, or subglobose. Isolated 
from sulphite pulp. Observed twice. 

Chaetomium funicolum Cooke—Culture gray blue-green; perithecia 
smaller; lateral hairs few, straight, rigid, septate, tapering to collapsed 
tip, olive brown at base to hyaline at tip; terminal hairs profusely 
branched dichotomously, with branches reflexed, roughened, dark 
olive brown at base to hyaline at tips; spores light olive brown, ovate 
to lemon shaped. Isolated from ground wood. Observed once. 


HYMENOMYCETES 


AGARICACEHEAE 


Paaillus panuoides Fr.—Mycelium white, becoming light cream 
with age, forming compact sheets over the surface of the medium. 
(See Pl. XVII, fig. 2.) In slant cultures, and sometimes in plate 
cultures, fairly large compact masses of hyphe are produced. The 
ae en eres are more or less fan shaped, either sessile or with a very 
short lateral stipe. (See Pl. XVIII, figs. 1 and 2.) They are pure 
white on top when fresh, becoming yellowish with age, yellowish 
brown below. The spores are yellowish brown. ‘This is one of the 
hymenomycetes which produces “‘red rust” or “red rot” in pulp. 
It isthe only one found on this occasion producing sporophores on pulp. 
It colors the pulp pinkish buff or cinnamon buff to cmnamon (dry), 


6 The culture numbers are given for those fungi which were used to obtain the data shown in Tables 13, 14, 
15, 16, and 17. 


60 BULLETIN 1298, U. S. DEPARTMENT OF AGRICULTURE 


or mikado brown to russet (wet). Pulp infected with this fungus © 
becomes very brittle. Isolated from ‘‘red-rusted” pulp, later from a | 
sporophore which developed on the same lot of pulp when placed in | 
a sterile Wardian case. ‘This is the only hymenomycete which was | 
found producing a fruit body. A very common species. i? ae 


UNIDENTIFIED HYMENOMYCETES 


In the absence of fruit bodies, which (with the exception above | 
noted) the investigators were unable to find o2 pulp or to develop 
in culture, there is no way by which cultures of hymenomycetes may 
be identified except by comparison with cultures of known fungi. | 
Although these species were compared with large numbers of known | 
hymenomycetes in pure cultures, none was definitely identified. For 
convenience they will be grouped as follows: Tae | 

1. Four cultures varying but slightly; mycelium soggy, appressed, — 
forming compact sheets over the agar; large, conspicuous clamps; | 
barrel-shaped or globose interstitial and terminal chlamydospores — 
(Pl. XVI, fig. 1), in more or less regular zones in Petri dish cultures, | 
white or cream colored, narrow or wide (Pl. XVII, figs. 4 and 6). 
These fungi bleach pulp somewhat, but are not vigorous wood de- — 
stroyers. Isolated from ground-wood (10918-10, 102019-1a, 6320-1) 
and sulphite pulp. Very common. ) 

2. One culture; mycelium soggy, appressed; differs from 1 in that 
the mycelium does not form such compact sheets over the agar; 
chlamydospores in more or less distinct radiating lines. (See Pl. 
XVII, fig. 5.) In older cultures small white tufts of mycelium | 
appear, scattered sometimes over the surface, but more frequently | 
around the edge of the plate. In jar cultures, and sometimes in — 
slants, dense masses of chlamydospores are formed on the surface of © 
the glass. (See Pl. XIX, fig. 1.) _Chlamydospores barrel shaped, 
ellipsoid, or somewhat lemon shaped, terminal or intercalary. Clamps — 
conspicuous. (See Pl. XVI, fig. 2.) Areas are cream-colored when ~ 
freshly infected, but become pinkish buff (dry) to clay color (wet), 
buffy brown (dry) to olive brown (wet), and finally mummy brown — 
(dry) to dark clove brown (wet). This fungus causes great damage ~ 
which, in severe infections, may become an entire loss, the pulp — 
becoming so brittle that it can not be used. (See Pl. XIX.) Tetinsed | 
from ground wood (82219-15). Common on ground wood and © 
observed once on sulphite pulp. 4 

3. Two cultures very nearly alike; mycelium soggy, appressed; 
chlamydospores in creamy masses or in small white mealy specks. 
Newly infected areas cream-colored, later pinkish buff (dry) to ecin- 
namon buff (wet), tawny olive (dry) to Chaetura black (wet). 
Infected pulp very friable, useless. Isolated from ground wood — 
(4620-1, 4620-2). €ommon. Ode F 

‘4, One culture; mycelium appressed, soggy, forming compact sheet; — 
clamps conspicuous; no chlamydospores. Does not discolor the pulp 
and causes very little damage. Isolated from sulphite pulp (6920-2). | 
Observed once. | 1M 

5. One culture; mycelium appressed, soggy, forming compact — 
sheets over surface of plates, with here and there fluffy white bunches 
of mycelium; clamps conspicuous; maize yellow, ellipsoid or globose 
chlamydospores produced on surface, forming a yellow mealy mass. — 


‘ 


Bul. 1298, U. S. Dept. of Agriculture PLATE XVII 


PETRI-DISH CULTURES OF HYMENOMYCETES ISOLATED FROM GROUND- 
WoobD PULP 


Fics. 1-5.—Ten-day-old growth: 
Fic. 1—Culture No. 92219-4 
Fic. 2— Pavillus panuoides 
Fia. 3.—Culture No. 82219-13 
Fic. 4.—Culture No. 102019-la 
Fig. 5.—Culture No. 82219-15 


Fic. 6.—Twenty-four-day-old growth of culture No. 102019-1a (ef. fig. 4) 


Bul. 1298, U. S. Dept. of Agriculture 


PLATE XVIII 


Fic. 1.—Portion of alap of ground-wood pulp rotted by Pazillus panuoides during a six months’ 
storage period in the basement of a New York mill. This type of rot is frequently termed 


“red rust)”’ 
Fic. 2.—Fruit bodies of Pavzillus panuoides developed at the laboratory from the samples of 


“‘red-rusted’’ pulp shown in fig. 1 } 
Fic. 3.—Ground-wood pulp severely molded during six months’ storage in the basement of 4 


the mill referred to under fig. 1 
‘ 


CONTROL OF DECAY IN PULP AND PULP Woop 61 


Pulp is not discolored by this fungus, except that the yellow chlamy- 
dospores are formed on the surface. It causes little damage. Iso- 
lated from ground wood (61520-1). Observed once. 7 

6. One culture forming a loose silky layer over the surface of 
medium and a very fluffy white margin. In old cultures the mycel- 
ium sometimes becomes cinnamon colored. Glistening droplets 
appear on the mycelium. White to cinnamon buff, warty hymenial 
patches are frequently formed on plate cultures. This fungus turns 
the pulp pinkish buff (dry) to cinnamon buff (wet). It causes con- 
Bidarhible oss in weight and makes the pulp very brittle. Isolated 
from ground wood (61020-1). A similar culture was isolated from 
spruce pulp wood. Observed once on pulp. 

7. One culture with loose, fluffy mycelium, white, later becoming 
tinged cinnamon buff; no clamps; no chlamydospores. Macroscop- 
ically this culture has all the characteristics of a hymenomycete. 
Infected areas become pinkish buff (dry) to clay color (wet), with 
scattered depressed white spots. It causes considerable loss in 
weight in the pulp. Isolated from white water (62220-1). Observed 

once. 

8. One culture with loose, fluffy, white mycelium, later becoming 
cinnamon buff. Some hyphez are very large, with whorls of large 
clamps (Pl. XVI, fig. 3); no chlamydospores. Bleaches the agar.’ 
Newly infected areas are pinkish buff (wet), later becoming deep 
-mikado brown. Isolated from fresh river water. Observed once. 

9. Two cultures of a loose, fluffy, white fungus, which on Petri-dish 
cultures produces rather compact zones of basidia bearing basidio- 
spores. (See Pl. XVII, fig. 1.) There is only a very slight difference 
between the two cultures, and they are probably two strains of the 
same species. Conspicuous clamps; chlamydospores. These fungi 
turn the pulp light ochraceous buff (dry) or ochraceous tawny eis, 
A fine mottling with white depressed spots is noticeable in the older 
infected areas. These fungi cause considerable loss. Isolated from 
- ground wood (82219-4, 6920-1). Common. 
10. One culture producing long, fine, white radiating mycelial 
strands. (See Pl. XVII, fig. 3.) It produces brown sclerotia-like 
bodies. Conspicuous clamps; no chlamydospores. This fungus pro- 
duces no discoloration of the pulp, but its presence is made evident 
by the long, glistening loose strands of mycelium found on opening 
up a lap of pulp infected with it, and by the sclerotia-like bodies. It 
causes only slight loss of weight in the pulp. Isolated from ground 
- wood (82219-13). Common on ground wood, and observed once on 

sulphite pulp. 


Funai IMPERFECTI 
SPHAERIOIDACEAE 


Cytospora sp.—Culture at first white, with scanty mycelium gath- 
ered in bunches, later becoming deep slate olive, reverse black; 
_ hyphe hyaline to deep brown; sharply defined stroma containing 
several pycnidia; conidia hyaline, allantoid, minute. Agar normal; 
pulp deep blue-slate-black. Isolated from sulphite pulp. Rather 
common. 


7 All culture characters given are those present when the fungi are grown on plain malt-bacto agar. 


62 BULLETIN 1298, U. S. DEPARTMENT OF AGRICULTURE 
MUCEDINACEAE 


Torulopsis rosea Berl—Hyphe obsolete; cells ellipsoid or globose, 
rose-colored en masse, usually budding at the ends, seldom formi 
chains. Agar normal; pulp slightly pink. Isolated from ground — 
wood. Common. eS 

Oidium sp.—Cultures wet and mucilaginous, occasionally mealy; 
septate hyphe irregularly branched, more distinct than is usual in 
Oidium, but they break up into typical oidia (simple segmentation — 
of the hyphz). The oidia vary considerably in length; are at first 
cylindrical, but when separated become rounded at the ends. (See — 
Pl. XVI, fig. 8.) This fungus causes little damage to the pulp. In- © 
fected areas are generally lighter in color than normal pulp. This | 
fungus is probably responsible in part for pulp in very wet condition — 
souring. Isolated from ground wood (62020-1). Common. . 

Papulospora nigra Hotson.—Mycelium. scanty, white, becoming 
dirty gray in very old cultures, clamp connections conspicuous; bul- 
bils colorless when young, becoming dark brown, then black, at 
maturity (Pl. XX, fig. 1), produced in large numbers, soon making 
entire culture appear black. No other means of reproduction known. 
The clamps indicate the relation of this species to the hymenomy- 
cetes. Hyaline mycelium penetrates the pulp; black bulbils are pro- | 
duced on surface, Isolated from ground wood (32019-7). Rather 
common. 

Trichoderma spp.—Nine cultures varying enough to be of distinct — 
species were isolated. Mycelium scanty, cottony, white or yellow, 
or compact, soggy, appressed, cream-colored to yellow; conidia in ~ 
heads at tips of the many branches of the fertile hyphe (Pl. XVI, | 
fig, 7), scattered cant ele over surface, in small or large patches, — 
or around the margin; conidia white, bluish gray, or reed-yellow to — 
light or dark American green. Agar normal, yellowed or browned; — 
infected pulp normal in color, yellow or green. These species produce ~ 
large masses of spores, most of which are American green, and make 
the pulp “dirty.” Some cultures dissolve cellulose. Isolated from 
ground wood (82219-10, 32019-1), from sulphite pulp, from river — 
water (6520-2). All very common. | bo¢ 

Trichoderma sp.—Mycelium scanty, white, rapidly covering the 
surface of the agar; small, white, compact bunches of conidiophores, 
SppeLae early, scattered over the surface. As conidia mature — 
these patches become pinkish cinnamon and, finally, cinnamon. ~ 
This fungus causes a slight browning of the pulp. Isolated from ~ 
ground wood (10918-4). Observed twice. 

Aspergillus spp.-—This group produces globose conidia in chains 
at the tips of sterigmata, which in turn are born on the inflated heads 
of the fertile hyphe. (See Pl. XVI, figs. 12 and 13.) None of the — 
species discolor pulp, but all sporulate abundantly on the surface. 

Aspergillus mger van Tiegh.—Mycelium scanty, st iene ; but — 
next to the glass, in slant culture, there is often a naphthalene yellow — 
or citron-yellow sheet. The surface of cultures is soon covered with 
a coal-black, powdery mass, formed by conidia. Isolated from — 
bleached sulphite and soda pulp. Very common. It is almost © 
invariably present in the ‘“‘sooty”’ blotches on pulp. hie 


8 Aspergillus and Penicillium should properly be classed with the ascomycetes, but since the ascigerous 
stage is known for only a few, they are often placed with the fungi imperfecti. 


CONTROL OF DECAY IN PULP AND PULP WOOD 63 


Aspergillus fumigatus Fres.—(1) Mycelium sparse, superficial, 
white; entire surface covered with dark bluish gray-green spores 
which become deep slate olive in old cultures. Agar greenish yellow. 
This fungus dissolves cellulose. Isolated from river water (6520-1) 
Common. (2) No superficial mycelium; entire surface covered with 
dark bluish-gray conidia which become deep slate olive in old cultures. 
Agar purple-brown. Isolated from sulphite pulp. Common. 

Aspergillus flavus group.—(1) No super cial mycelium; surface 
covered with parrot-green conidia which later become brownish olive. 
Isolated from sulphite pulp. Common. (2) Mycelium loose, fluffy, 
white, around the margin of young cultures, but soon covered with 
mignonette-green conidia which become brownish olive in very old 
cultures. - Isolated from bleached sulphite. Common. 

Penicillium spp.—Conidia globose or ellipsoid, borne in chains on 
the tips of sterigmata, which are small branchlets at the top of the 
unequally verticillately branched, uninflated fertile hyphxe. (Sée 
Pl. XVI, figs. 9 and 14.) Some of the species discolor the abet t all 
of them produce spores in sufficient numbers to make the pulp 
“dirty.” The species isolated may be described briefly as follows: 

Penicillium brevicaule group.—Mycelium scanty, appressed, soon 
covered with pinkish buff to avellaneous conidia, which later become 
cinnamon brown. Agar slightly darkened; pulp not discolored. 
Isolated from ground wood (81318-2). Common. | 

Penicillium divaricatum group.—Mycelium scanty, superficial, soon 
covered by a smooth layer of conidiophores with light brownish-olive 
conidia. Agar very dark brown; pulp slightly browned. Isolated 
from ground wood. Common. 

Penicillium pinophilum Hedge.—Mycelium scanty, superficial 
when grown on malt agar. Cultures soon become dark bluish 
glaucous mixed with a little yellow-green due to conidia. Agar dark 
red; pulp pink to red. Seldom HH cote eng large numbers of spores on 

pulp, but the reddening is sufficient to give an off-color paper. 
According to Thom (26) it produces orange to red stains in pine wood. 
Isolated esti ground weod (112217). Very common. 

Penicillium mee een O. Stoll—Similar to P. pinophilu 
when grown on malt agar, but no yellow present in the spore surface, 
which is somewhat smoother. Agar red to purplish vinaceous in old 

cultures; pulp pink to purplish red. Isolated from ground wood 
(10918-1 1) and sulphite pulp. Very common. 

Pemecillium commune Thom.—Mycelium scanty, soon covered 
with celandine-green conidia, which become gnaphalium green or 
even dark olive. Older cultures more or less overgrown with white 
floccose mycelium. Agar and pulp normal. Isolated from ground 
wood (10918-3). Common. 

Undetermined Penieillvum paenine: ine cultures, varying enough 
to be distinct species, were isolated. Mycelium soggy, appressed, or 
cottony ; floccose, scanty, or abundant; white, reed yellow, or colonial 
buff; conidia bluish gray-green, grayish blue-green, pistachio green, 
glaucous, citron or glass green to light brownish olive, ecru olive, 
mytho, dark ivy, or dark American green; surface dry, or covered 
with droplets of clear, amber, or pink liquid. Agar normal, yellow, 
green, or brown; pulp normal or slightly browned. One culture dis- 
solves cellulose. Isolated from ground wood (10918-9, 82219-12), 
sulphite pulp, soda pulp, and river water (6520-3). All very common. 


64 BULLETIN 1298, U. S. DEPARTMENT OF AGRICULTURE 

Two cultures similar to P. pinophilum but both producing black 
sclerotia-like bodies. Conidial surface as in P. pinophilum, or glass — 
green to tea green. Agar red; pulp pink to red. Isolated from sul- — 
phite pulp. Each observed once. 

One culture with mycelium white to cream-colored, cottony, soon 
covered with white ascigerous masses, conidial fructifications rather 
rare. Agar normal; pulp slightly browned. Isolated from ground 
wood. Observed once. | 

Citromyces sp.—Macroscopically appears like Penicillium, but dis- 
tinguished by the somewhat inflated conidiophores bearing a single 
whorl of sterigmata. (See Pl. XVI, fig. 5.) Mycelium scanty, white, 
or soggy, appressed; conidia deep bluish gray-green, or deep glaucous 
pray. Agar normal or yellowish; pulp made ‘‘dirty” by spores. 
Isolated from ground wood (10918-6, 10918-12). Common. 

Gliocladium sp.—Mycelium very scanty, loosely floccose; conidio- 
phores Penicillium-like (Pl. XVI, fig. 15), except that they are 
widely scattered over the surface of the cultures so that no solid mass 
of them is found. Spores held in a deep American green mucus 
which is soluble in water and sometimes is produced in such amounts 
that the pulp becomes dyed with it. Isolated from ground wood 
(10918—1) and sulphite pulp. Very common in all kinds of pulp and 
river water. 

Verticillium sp.—Mycelium sparse, superficial, hyaline or very 
light brown, soon covered with cinnamon-drab conidia borne singly 
at tips of loose verticillately branched conidiophores (Pl. XVI, fig. 
10); conidia held together in heads. Pulp slightly browned. Iso- 
lated from ground wood. Common. 

Spicaria sp.—Mycelium appressed, soon covered with white to © 
cinnamon-buff fructifications. ‘The conidiophores are branched in — 
loose verticils (Pl. XVI, fig. 19), thus differmg from Penicillium, 
which has close verticils. Underside of culture is brown, and in — 
older cultures the agar becomes dark brown. Pulp browned. Iso- — 
lated from ground wood (10918—5). Observed once. : . 

Unidentified Mucedinaeeae—Several other Mucedinaceae were 
isolated from pulp, but since they caused no perceptible damage and 
were not common, notes on them are omitted from this report. One 
species which caused a yellowing of the pulp is described as follows: 

ulture deep colonial buff to tawny, appressed to downy; hyphee 
hyaline to yellowish; some large, rigid, light yellow-brown filaments 
in clusters; many cylindrical oidia of various lengths. Agar and 
pulp, colonial buff to tawny. Isolated from sulphite pulp. Common. 


DEMATIACEAE 


Torula sp.—Hyphe hyaline, soon becoming very dark brown, 
mostly submerged, breaking up into chains of one-celled, dark-brown 
spores. Pulp very dark neutral gray. (See Pl. XVI, fig. 11.) Iso- 
gett from sulphite pulp. Common on sulphite and ground-wood 

ulps. 
2 dik: Riieactoes sp.—Culture dull black, appressed, with white pow- 
dery masses on surface; hyphe hyaline, then brown, breaking up into 
chains of one-celled, dark-brown chlamydospores; many hyaline, 
oidia-like conidia produced endogenously. Agar normal; pulp gray. 
Isolated from ground wood. Observed once. \ 


— a se eS ele. 


Eye ————=—E i. de 


—~— 


CONTROL OF DECAY IN PULP AND PULP WOOD 65 


Stemphylium sp.—Culture green-black, reverse jet-black; myce- 
lium decumbent, hyaltie to brown, scanty; conidiophores decumbent, 
irregularly branched; conidia large, muriform, very dark brown, 
mostly ovoid. (See Pl. XVI, fig. 21.) The brown hyphe intertwine 
the fibers, producing olive-black areas in the infected pulp. The 
large, dark spores are frequently found in “‘sooty” spots. Isolated 
from soda pulp. Common. 

Alternaria sp.—Culture velyety, pale to deep olive gray, reverse 


- black; mycelium hyaline to brown; conidia obclavate, muriform, 


brown, single or in chains (12 spores have been observed in one 
chain) at the ends of conidiophores which vary but little from the 
regular hyphe (Pl. XVI, fig. 20); chains sometimes branched. This 
species produces small, round, brown spots inground wood. Isolated 
from ground wood (32019-2). Common. 

Unidentified Dematiaceae.—Mycelium hyaline becoming brown, 
often in heavy decumbent strands. 

1. Cultures dark olive gray or grayish olive to mouse gray, reverse 
black; conidiophores short, rarely branched, brown at base to sub- 
hyaline or hyaline at roughened tip (Pl. XX, fig. 2); conidia fusoid 
or ellipsoid, subhyaline to hyaline. Agar red-brown or normal; pulp 
eray. Isolated from ground wood (3818-1, 82219-5). Very common. 

2. Cultures mouse gray, drab, or dark snuff brown, reverse brown- 
black; mycelium downy, cottony, or fluffy to feltlike; conidiophores 
branched or unbranched, lateral branches of ordinary hyphe, hyaline 
to light brown, ends open to form a “‘collar’”’ which is slightly flaring 
(Pl. XVI, fig. 6) and concolorous with conidiophore, bell shaped and 
dark brown (Pl. XX, fig. 3) or widely flaring, saucer shaped and dark 
brown (Pl. XX, fig. 4). Conidia borne singly at tips of conidiophores, 
held together in Devt ; hyaline, subhyaline, or fight brown; ovoid, 


ellipsoid, or globose. Agar normal or bleached; pulp dark neutral gray, 


olive gray, or brown-black. Isolated from ground-wood (81318-1, 
10910-7, 82219-18, 82219-2) and sulphite pulp. Very common. 

3. Cultures olive brown to black, or mouse gray to dark grayish 
olive, reverse black; hyphe dark brown, frequently coiled; conidio- 
pages Penicillium-like, dark brown at base to hyaline at tips of final 

ranches; conidia globose, small, hyaline, borne in chains at tips of 
conidiophores. Agar normal; pulp dark neutral gray. Isolated from 
ground-wood (82219—9, 82219-23) and sulphite pulp. Very common. 

4. Culture soggy, appressed, cream to cinnamon; hyphe hyaline; 
conidiophores short, rigid, septate, brown below branches, branched 
irregularly, tips hyaline; conidia hyaline, ovoid or ellipsoid, borne in 
short chains at tips of conidiophores. Agar normal; pulp cinnamon. 
Isolated from sulphite pulp. Rather common. 

5. Cultures deep olive gray, reverse brown; mycelium hyaline or 
brown, sometimes in strands, not superficial; conidiophores short, 
rigid, brown at base, hyaline toward tips, branched in irregular whorls; 
conidia oidia-like, in chains at tips of conidiophores, hyaline. Agar 
slightly darkened; pulp olive gray. Isolated from sulphite pulp. 
Common. 

TUBERCULARIACEAE 

Fusarvum sp.—Mycelium scanty, hyaline to light brown; chlamy- 
dospores brown, rough, globose; conidia mostly one or two celled. 
(See Pl. XVI, fig. 17.) Agar red; pulp orange vinaceous. Isolated 
from sulphite pulp. Observed once. 


§23°—25{[——5 


66 BULLETIN 1298, U. S. DEPARTMENT OF AGRICULTURE 


Fusarium sp.—Mycelium scanty, pinkish; no chlamydospores; 
sporodochia small, discoid, Mars brown; conidia one to five celled. 
Agar slightly purple; pulp deep purplish vinaceous. Isolated from 
sulphite pulp and ground-wood. Observed twice. 

usarvum sp.—Mycelium very scanty, white, no chlamydospores; 
sporodochia cream, light Terre Verte to neutral red; conidia mostly 
five celled, very few one celled. (See Pl. XVI, fig. 16.) Agar slightl 
red; pulp deep purplish vinaceous. Isolated from Pi 
Observed once. ’ 

Fusarium amide aise mealy to subgelatinous, from white to pale 
cinnamon pink; hyphe hyaline; numerous pink intercalary chlamy- 
dospores; spores abundant, small, ovoid, hyaline, apparently pro- 
duced in clumps at ends of branches (Pl. XVI, fig. 18); very few 
typical Fusarium spores found; no well-defined sporodochia. Agar 
normal, pulp light pinkish cinnamon. Isolated from ground-wood 
(32219-1) and sulphite pulp. Very common. 


CLASSIFICATION OF ORGANISMS BASED ON COLOR CHANGES IN PULP 


The fungi just described have been grouped according to their 
morphology, which is the true mycological classification. In the 
following key the fungi are grouped according to their color reaction 
on pulp. This key is an attempt to present the fungi in such a way 
that those least familiar with them may be able to determine which 
organisms may be present and thus to decide whether an organism is 
a hymenomycete, causing a loss in the wood fiber, or a mold, producing 
simply a discoloration of the pulp. Each of the fungi investigated 
either (a) bleaches pulp, (6) causes no color change in the pulp, 
(c) produces a color change which may be due either to chemical 
disintegration of the pulp itself or to pigments produced by the 
fungi, or (d) produces a color change which is due to the colored 
mycelia which are scattered through the pulp. The key classifies 
the fungi described above according to these color effects, as follows: 

Organisms that bleach pulp. 

Broaqichii no superficial spores. 
Hymenomycetes, Ordium sp. 
Organisms that cause no color change in pulp. 
Producing no superficial spores. 
Hymenomycetes. 
Producing superficial spores. 
Spores maize yellow. 
Hymenomycetes. 
Spores green or blue. 
Trichoderma spp., Aspergillus spp., Penicillium spp., Citro- 
myces spp., Gliocladium sp. 
Spores black. 
Papulospora mgra, Aspergillus nager. 
Spores brown. 
Trichoderma sp., Penicillwum sp., Verticrllvum sp. 
Producing superficial ascocarps (fruit bodies). 
Asci in apothecia (open, saucer shaped). 
Peziza repanda, Orbilia rubella. 
Asci in perithecia (nearly closed, globose). 
Chaetomium globosum, Chaetomium funicolum. 


CONTROL OF DECAY IN PULP AND PULP WOOD 67 


Organisms that cause spots in pulp not due to colored mycelia. 
Producing no superficial spores. 
Pulp some shade of buff, brown, or black. 
ymenomycetes. 
Pulp pale pink. 
Torulopsis rosea. 
Producing superficial spores. 
Pulp some shade of red. 
Penicillium spp., Fusarvum spp. 
Pulp some shade of yellow or green. 
Trichoderma spp., unidentified Mucedinaceae. 
Pulp some shade of brown. aes 
richoderma sp., Penicillium sp., Spicaria sp. 
Organisms that cause spots in pulp, due in part at least to colored 
mycelia. , 
Pulp light brown. 
Verticillium sp. 
Pulp dark brown. 
Alternaria sp., unidentified Dematiaceae. 
’ Pulp some shade of gray. 
Torula sp., Thielaviopsis sp., unidentified Dematiaceae. 
Pulp blue-slate-black. 
Cytos ora sp. 
Pulp olive black. 
Stemphylium sp. 


_ PHYSICAL AND CHEMICAL PROPERTIES OF GROUND-WOOD 
PULP DETERIORATED BY SPECIFIC FUNGI IN PURE CUL- 
TURES 


PHYSICAL PROPERTIES 
PREPARATION AND EXAMINATION OF SAMPLES 


The series of tests to determine the specific action on pulp of 
various fungi in pure culture was comprehensive in scope, repre- 
senting about half of the species isolated. The test medium was 
fresh, clean ground wood made up of spruce, 70 per cent, and balsam, 
30 per cent. The pulp was cut up into pieces 24% by 10 inches, all 
of which were oven dried (100 to 105° C.) and weighed, then soaked 
in distilled water, folded twice, and tied with thread. The culture 
chambers used were 2-quart fruit jars, which were prepared as follows: 
A piece of galvanized screen, 2144 by 5% inches, was bent down 1 
thidh from each end; this was placed in the bottom of the jar, and 
~ 100 cubic centimeters of distilled water were poured in. Three pieces 
of pulp, weighing 90 to 100 grams in all, were then placed in the 
jar on the screen, which supported them above the water. (See PI. 
XIX, fig. 1.) A small extra piece of pulp, to be used for cultures and 
color comparisons at the end of the experiment, was placed in each 
jar, in close contact with the other samples in order to insure infec- 
tion. The jars were then capped with a layer of cloth, a layer of 
cotton, then the top piece of the can lid, and finally with a layer of 
cloth over all. Two large rubber bands were used to fasten the cap 
in place. The jars were then sterilized by steaming in an autoclave 
- at 100° C. for one hour on each of three successive days. After the 


68 BULLETIN 1298, U. S. DEPARTMENT OF AGRICULTURE 
last sterilization they were transferred immediately from the auto- 
clave to the inoculating case, in which they were allowed to cool. 


Sets of three jars each were inoculated with a pure culture of a 


fungus that had been isolated from pulp, pulp-wood, boards from 


pulp sheds, or river water. The following two methods of inocula- 4 


tion were used: 


1. In the case of molds, a sporulating culture on a malt agar slant — 


was used as the source of the inoculum. Five cubic centimeters of 


sterilized distilled water were poured into the culture tube, which was _ 


thoroughly shaken until a heavy spore suspension was obtained. 


Then three test tubes containing sterile water were opened and a 


third of the spore suspension was poured into each. The three spore 
suspensions resulting were then used to inoculate the pulp samples. 
One side of the jar cover was carefully lifted and the spore suspension 


poured over the tops of the pieces of pulp in the jar. Care wasexerted | 


to have the inoculation of the pieces of pulp as nearly uniform as 
possible, so as to establish a check. 


2. The cultures inoculated with wood destroyers were treated as 


follows: Petri-dish cultures of the fungus in question were made on 
malt agar a week in advance, after wield time they were cut into 
pieces about 8 millimeters square, and one square was placed on the 
top of each of the three pice of pulp in the jar. The jars, as in- 
oculated, were removed from the culture case. New rubber bands 
were substituted for the old ones, and white papers, to keep the dust 
from the caps, were placed over the tops andi 

rubber bands. : 


All the jars were then stored in an inside basement room in which 4 
the temperature was fairly constant (average 21° C.). The three © 


jars of each set were opened at the end of 6, 9, and 12 months, re- 


held in place by heavy | 


spectively. At the end of the test the moisture content of thesamples | 


was determined, and the loss, based on oven-dry (100 to 105° C.) 


weight, was obtained for each culture. As each jar was opened the | 


small extra piece of pulp was transferred to a sterile Petri dish and 
small pieces of it were then planted. upon malt agar plates. The 


object of this procedure was to determine whether or not the fungus — 


had remained viable throughout the experiment and whether the 


culture had remained pure. Results in these respects were positive 


except in the cases specially noted in the tables. 


DATA AND DISCUSSION 


Table 14 gives the results obtained with 29 cultures of molds, — 
representing at least 26 distinct species. The loss in weight was small — 
in all the mold-inoculated pulps. Trichoderma sp. (6520-2) caused — 


the greatest loss in 12 months, 3.2 per cent. Four-samples became 
some shade of pink, and nine became gray. Only three samples, 


which were gray, were dark enough to have spoiled the quality of © 


onthe — 
surface of the pulp, were in sufficiently small numbers and of such 


paper made from them. The remaining 16 samples were recorded 


as “‘normal,” which means that (1) the poe itself retained its usual 
p 


color; (2) the fungus did not make the brittle, or, in so far as 
could be determined macroscopically, otherwise change its payee 
properties; and (3) the colored spores of the fungus, produced 


kind that they would ordinarily be washed off in the beater without 
causing any damage to the manufactured paper. ete 


Bul. 1298, U. S. Dept. of Agriculture PLATE XIX 


Fic. 1.—Nine-months-old pure culture of pulp infected with a wood-destroying fungus, culture 
No. 82219-15, sample No. 25 

Fic. 2—Clean pulp 

Fic. 3.—Piece of pulp, similar to fig. 2 originally, after infection for six months with culture 
No. 82219-15 

Fic. 4.—Block of white spruce wood completely rotted in six months by same fungus 


Bul. 1298, U. S. Dept. of Agriculture PLATE XX 


REPRESENTATIVE MOLDS ISOLATED FROM GROUND-WOOD PULP 


Fic. 1—Bulbils of Papulospora nigra (X 150) 


Fic. 2.—Conidiophores, spores, and mycelium of an unidentified species of Dematiaceae, cul- 
ture No. 3818-1 (X 750) 


Fic. 3.—Conidiophores and mycelium of an unidentified species of Dematiaceae, culture No. 
10918-7 (X 750) 


Fic. 4.—Conidiophores, spores, and mycelium of an unidentified species of Dematiaceae, 
culture No. 92219-2 (X 750) 


CONTROL OF DECAY IN PULP AND PULP WOOD 69 


Although at the outset care was taken to bring the pulp in the tests 
to a uniform condition of moisture the tables show that at the end the 
individual samples varied considerably, ranging from 53.6 to 73.3 
per cent in moisture content. The average was 65 per cent, as com- 
pared with the approximately 70 per cent which pulp normally has 
when taken from the wet machines. 

Table 15 gives the results obtained with 13 species of hymeno- 
mycetes—12 isolated from ground wood, and one (6920-2) from 
sulphite pulp. It will be noted that the figures recorded in Table 
15 show results quite different from those in Table 14. Seven organ- 
isms caused sufficient color changes in the pulp to have appreciably 
discolored any paper manufactured from it. Five fungi made the 
infected pulp more or less brittle, and three caused it to become 
friable to the point of entire worthlessness. The most destructive 
of these organisms are those which are found most frequently on 
ground-wood. 

The moisture content of the pulp samples at the end of these tests 
- was somewhat higher, averaging 68.7 per cent, than in the tests made 
with the molds, although efforts were made to start all exactly alike. 
The condition may be accounted for in some cases by the fungus 
growing down into the water in the bottom of the jar, whence it con- 
ducted moisture to the pulp. All but two of the cultures remained 
viable until the end of 12 months. The two that died are not classed 
as vigorous wood destroyers. 


TaBLE 14.—Deterioration of ground wood caused by 29 cultures of molds isolated 
from pulp and water 


Per cent loss in weight 


Per after— 
nate Culture No. Organism on. ge Fe Re si tee 
ture 


6 9 12 
months} months} months 


—_—_—_—— |) —— | Sees 


LC oe je i (cee aaaieaetar Ae Gann Get are’ ae A | (ae (C15 Sa gle 
Pe mMMOGINIALCd 6 Pn ed ne 4 en a [Sane OS) te Se ae Normal 
198 Ottis. |Samee aulect sees 
88 69. 0 se Ua fap aia 2 | aloe 
89 |}82219-11_________ MALCOrSp 228.23 Berle Gly 1 Ob | see ears Do 
GaN Gh eee. Eee so 8 
181 66. 6 co EE Se apee p | Me7 e 
182 |+62020-1__________ Onliwm sp... 4.85. _ 3. Cola fay I a Sil ae Do 
183 GaSe es eas ea. 5 1.4 
(SESS Se AR rae Somme Se Gane a See sees FF eg Pr 
64 |}32019-1__________ Trichoderma sp-__....--_- GAS tule sie He ess ME Do 
66 BTRIGH | sees <2 | tee 1.0 
85 66. 8 Lit | ERA gs Pa ee. 
86 |/82219-10_________|_.-- Goel, 229 ty pois SE (a3 a (eres TOs esse 2s Do 
ep ( 0) I ey aa ates (aan ne? 
190 66. 4 1 Soil eae a Ries 
192) |>6520-2 2. ts _<.-2 |e 22 Gos ach 224 -eee ot Go ees 1 Is fe ete ee Do 
191 EE Dip Mereeasceblens| ennai vista 2M, 
112 72.4 i 2h eae ts BIE 
113 |}82219-6_________- Husarinm Spots. (hag a eee 1 Ses Soe Nat Very slight pink. 
114 LS yt Ue | atl 2 neg A hel 
187 64. 7 1 Sol eee ee ae ae 
188 |-6520-1 ?______-____ Aspergillus fumigatus___|{ 71.2 |_._-___-- i ee | eee ee a Normal. 
189 Mone aes Sele te ey 3.0 
EIR IC REE eee rae een cette iy ce | (2 Be | las ae (Sato omar 
7 | pelole-2- = _ 5 Penicillium sp_--.------- iiccak: | eee TEA) ee pees Do. 
18 Ber Oe eee ate. 22 ei 6 
SE ep ee eo 1 ike IEICE aac | Se eas 
20 |7-10918-9_____-__- Jo Mon CAT Mae Gis) (abo tee gy psa ei Do 
33 AGE We LSS St (a gE 1.5 
SINE it ane SME Seat lee | NO SURIA ical (RMU, ° fi oe en | ane acpa 
er PROOLS—32 28 ou kess|_u. dow... 025% umes 67.8 (sok he 8 he. She Do 
-_ 1 ee i iin NS aS SE iain) vt Mca; © Ae | pan ee) 2.0 


1 Contaminated with Penicillium sp 3 Isolated from water. 


Je ate o 
4A9 eG 


70 BULLETIN 1298, Uv. Ss. DEPARTMENT OF AGR CU 


TABLE 14 nepali of ground wood caused by 29 cultures + of molds 
from pulp and water—Continued beh sts 


Per cent loss in wig ac ay 
after— 5 


—? Culture No. Organism 


—— 


53 1091811 cage © Penicillium purpuroge- 
54 num. 


1 
92 |782219-12- _ _-_ a2. Penicillium sp____-_-- at 


ee 


O85 4 pIS2M7E. 2) Pies Penicillium pinophilum. 


eee 


194 |'6520-32_...____- Penicillium sp..-_..----- 


44 fos. OS ee Citromyces sp_---------- "1 ae 


Se ee 


10918-1___.___-__ Gliocladiwm sp_---_____- A beh 


55 ick tm 
56 |710918-12_________ Citromyces sp__--------- i i eae t _|$ 
10918-5_-_.______ Spicaria spsiet Libis. 


10 01-2 5 ae 
PL 173201972. ee Papulospora nigra______- ‘ Ravn ge. 4% 
S2019-2,_= me. _ Alternaria sp_----------- 


41 frois-s SESE Trichoderma sp___---___- @aeriges 


woe -- -|-- - 


7 |}3818-1__......-__| Unidentified --__--__._- pee ee 7 sana, ight | sain 
8 , lh = 5 ee ees JN sas rn 
13 ,0)|--...-_ 1 __ 2a | 
14 |}81318-1_-___.____|_____ do! wy.2. Reeear 8 (cu > ie 


es oo 

Stet to 

were ne ee | ee ee eee 
eS 


ee 


2Tsolated from water. 


—--* o 


71 


CONTROL OF DECAY IN PULP AND PULP WOOD 


TaBLE 15.—Deterioration of grownd wood caused by 13 hymenomycetes which 
were isolated from wood pulp 


Per cent loss in weight 


1 Contaminated. 
2? This culture was lost. 


ie a Culture No. Organism cous, Physical condition of pulp 
ture 6 9 12 
months} months} months 
196 Ae AN BRO EEL SYOSIEE BL Oneaices. sist eth 
me eomocunahs Ye i se Normal. 
ed 
198 , 67.3 eer iy ty aceon 0.6 
32 ae = me scfinie | [eee Reale! et) eee i 
Paritl us tj Pinkish buff to russet; slightly 
Ol spenn0 a ranuotders lf SB fa—o——nn-|— 28 Fa af brittle, 
eh Ted or le eet a Ochraceous buff or tawny, 
4 82219-4 | Unidentified_-|{ 74.2 |-------- SG et a. mottled with white; slightly 
6 v7 8 be pak Sc rae brittle. 
SSS TSS, EPR | Sina enema aa || (Pe a oi J 1b We” ae | ee A SS 
22 82219-13 |_____ GO.2t et rp Ee) fe Ramana a ye Normal. 
= 66. 5 sai) Gaueent 3. 4 
25 ||  g2219-15|._..do........) ited a ce es, colon e) olarg ‘brown; 
os TRL Gee Ce Ee be ee a 26. 4 
Lae eokae he to tN eee Pethyt| eed wee et 
oo Cae Ol a aS a ae. (0s See Goa Lob yey) eee Se Normal. 
ra 4547220522 sean ey Page 
Meee Le at SS Ee a a 
50 10918-10 |_____ do tae. Sey, | es Be 13h 
on ie: 4S Pe Sa ee 3.6 
) 75.0 of fs 1d eae S| RS 
- Cinnamon-buff to chaetura 
a 4620-2 |____- do__-------|)-- mail... () Pray BY black; very friable. 
106 TO || 999d) 4 dt ahs 
107 4620-1 |____- do.3.. 2%. [te ae ae ae 5 Ee PS 
oH aH eat ee: 2 ee 38. 6 
i ee “HD Sp] (ee: ee | ee ae Sa 
128 61020-1 |____- G@024 2 a2 A | ee 18.0 qceee oa Cinnamon-buff; very brittle. 
io s pe bee», Vie ee Se 18.9 
70.1 Dil apt He 
ee her tee de eb EP Ra pd. Seen pra yeaa s Normal, except maize yellow; 
oH 61520-1 |---.- do.------.- er GS TE 3.1 F901 chlamydospores on surface. 
163 TS ee eee ee 4 
164 f 6920-2 |____- do: 2212.4 (2 S00 | a eae te. 2. Bae 2 Normal. 
a Ed PE ele} A ee 32.3 
68. ALD. oe A et 
167 6320-1 |____- ee ete ep iy ee ae ae ity? h | ai Re Normal color; somewhat brittle 
168 GO Gil a ee 6.8 
172 67.3 CE Ee BE | fe SS Ochraceous buff or tawny, 
173 6920-1 |_____ q022—- 6202235 ee: en by | a. mottled white; slightly brit- 
174 GOr Ge re este 23 7.9 tle. 
CAG ee le ee 68. 7 8.8 10. 6 15.3 


3 Transplants did not grow. Results of this set not included in averages. 


The loss in weight in 6 months varied from 1 to 27.1 per cent. 


In 9 months from 


The average loss in 6 months was 8.8 per cent. 
1.8 to 33.1 per cent was lost, the average being 10.6 per cent. In 
12 months from 2.3 to 49.5 per cent loss occurred, the average being 
15.3 per cent. (See fig. 2.) 

Table 16 records the results obtained with 11 hymenomycetes 
isolated from wood and one isolated from water. All except one of 
these fungi discolor pulp to such an extent as to damage the paper 
made from it. Hight species made the pulp more or less brittle, and 
one made it so friable as to be absolutely worthless. The moisture 
content of the samples varied from 55.8 to 72.5 per cent, the average 
being 64.7 per cent. Four of the fungi died before the end of 12 
months, these being the least virulent of this group of wood destroyers. 

The loss in weight in 6 months varied from 1.8 to 21.5 per cent, 
the average loss being 10.5 per cent. In 9 months from 2.2 to 30. 3 


72 BULLETIN 1298, U. S. DEPARTMENT OF AGRICULTURE 


per cent was lost. The average loss was 14.4 per cent. In 12 
months from 5.5 to 40.2 8 cent was lost; average, 18 per cent. 
re sets of tests in which the fungi died are not counted in the 
results. 

The loss in the check cultures shown in all three tables is to be 


attributed to the changes brought about by sterilization and drying — 


and to some slight loss due to handling; hence an experimental error 
of from +0.4 to +0.6 per cent should be allowed in all cases. 

It will be observed that in some instances the loss in weight in 12 
months was less than in one of the shorter periods. The ollowing 


Eel CO ae 
SCE E EEE EEE EEE EE ae 
/ | 
PT Pea a ae er 
Poe bb beh aS 
POPP Te EES 
7 Pee MMMM Rik 
PEER 
: ate 
, CEE AREF aS ME 
fy NE iE Lee EP4aP aah 
pe ee i | ee 
oP eo a 
© GEER 
wn fi / | 
8 PEE EEE EEE Eee 
Ww 4 ¢ 
g DEMS 4p 2mnheBee es 
2c 
PE A 
El A er 
Vi - pases — 
seeur aaeedee auaenaaae| 
10 LAL Z| LL | | ym ee 
ERGPCA2DU6P2SReeReSeees 
y, 7 = Be 
Sapa 62a Eeeee eee 
A Aer ee esermeeer T 
Af | s a= aes 
2722.60 > = eee 
WZz BA A 
a 6 5 , a 


Time ~months 


Fig. 2.—Graphs showing loss in weight of ground-wood pulp after infection in pure culture by various 
wood-destroying fungi . ; 


facts are offered in explanation of this apparent anomaly: Some, at 
least, of the tests indicate a decrease in the vitality of the organisms. 
Moreover, the weight of the fungous mycelium has not been taken 


into account; this will vary considerably, according to the nature — 


of the fungus in question, and may amount to as much as several 


grams. Buromsky (8) reports a growth of 2.4 grams for Aspergillus — 


niger when grown in favorable culture solutions, whereas some of the 
species used in the tests, especially among the hymenomycetes, 
produce a much more luxuriant growth of mycelium than does 
Aspergillus niger. 


~ 


4 
4 
4 
3 
4 
A 


CONTROL OF DECAY IN PULP AND PULP Woop 73 


TaBie 16.—Deterioration of ground wood caused by 11 hymenomycetes isolated 
from wood and one from water 


Por Per cent loss in weight 


Sample cent 5 ; ti 
iP’! Culture No. | Organism | jiois- Physical condition of pulp 
ture | § mos. | 9 mos. |12 mos. 
Pane ee AAP ESS SR ee CT ok Orbea tiie 
a | uninoculated Shek pesteeyte gas han ang: alt ae @) erg a Normal. 
1 = Yc cl Sa te i 
157 : : 67.6 PASH} SL FPS S- . Se- : : 
Lentinus lepi- Cinnamon to sayal brown; 
ats 61420-1-- ___- { Cum ee eh | a TS ee 30. 3 “""40.2|{ very friable. 
130 TB by {10,3422 -seeecbaz--<2=4 Cinnamon-buff to clay color; 
oH 1420-2____-- Fomes roseus__|4 67. 4 2, wont odie 12.9 ere ae amowhat briktic: 
139 eS ae Sener 
140 |/62520-1.--.-. apt ee ie ad 62.8 J. 22 |-2--|pCinnamon. 
141 =t £5 = ht OR aie rn ee pe 
142 < 62. 0 >A); (Ole Ge OS as SS 
143 |762520-2.--___ gor eal ge 60.4 | 83 |---{Cinnamon-bus. 
1 ees 1A See SS SR 
148 : 70. 0 fs. ON. 9 oe eet 
149 |}8620-1___-___ P epicure ta- PAGS ee L-- (ORE Sel fe Jolie Cinnamon-buff; very brittle. 
151 gtk ee ao a 2 ee BS ee 2 22. 4 
136 62.8 a (og | eget onal |ocah ely Seon 
137 |?61420-3- - ____ Unidentified __ ie oe eo 1s a Se ae Be Pinkish buff; very brittle. 
. 138 60. : Pee ne ee 18, 1 
145 63. 3.2 |.-------|-------- Cinnamon-buff to clay color; 
146 |(62220-1 9... |... i. ee ee 4.2 |--------\( slightly brittle. 
152 67j0i| 7.94.1.) | 4... x 
Tp 1761490-7 2222 oe 2 do's a2 eS a TE: 2 OS SB Cinnamon-buff; very brittle. 
153 Sp A Gee eee | ee Peter 16. 1 
154 67.6 oa) | rae ap ely oe apc 
Pop. |pnl4a0-pe — .) 2...) doit 6Bi 1 i. Sa 4 pi HTS gies Bae Normal. 
a 61.8 ‘See Gee 22.3 
1 65. 6 We See ON Fe ee Se 
161 \si490-4. Su ee Ss Ot i ee 6319 [2.58.2 26) Cinnamon-buff; slightly brittle. 
64.6 pas, Gaia 22.4 
175 66. 6 AH {|| ee. Sal be Sa 
176 Va aes 5 Sa pape | pane 0 0 ie Spee 60; 9-|22-4-..3 Be OSI ke foray color; slightly brittle. 
ie on i I |; Be EO | en,” Se 7.6 
1 69.3 a Ts Se 
179 |7-4620-3__-____|---_- "ic = oo 63)4.):-. 4-9 16.62) }cimnamon-bud ; very brittle. 
180 yA | ieee ay | ee eS: 20. 4 
a Se Re ee 64.7 | 10.5| 144] 18.0 


1 Contaminated. 
2 Transplants did not grow. Results of this set not included in averages. 
8 Tsolated from river water. 


Trichoderma sp. (6520-2), Aspergillus fumigatus, Penicillvum sp. 
(6520-3), and P. pinophilum Les cellulose when planted upon cellu- 
lose agar (McBeth and Scale’s formula) and kept at 28° C. In the pulp, 
at about 21° C., however, they produce a loss in weight of only 1.4 
to 3.2 per cent, which is far below what might be expected of cellulose- 
dissolving organisms. Under commercial methods of storage T'rich- 
oderma sp. (82219-10) turns pulp bright yellow; Penicillium pino- 
philum and P. purpurogenum and other species of Penicillium pro- 
duce red discolorations which vary from light pink to purple-red; 
Spicaria sp., Alternaria sp., and two unidentified cultures (82219-2, 
82219-18) cause brown spots which would appreciably lower the 
quality of paper made from pulp infected by them; and eight of the 
unidentified molds (3818-1, 81318-1, 82219-5, 82219-9, 10918-7, 
———-- 82219-28, and 82219-21) produce gray pulp. 

is Since the more pronounced discolorations common to the above 
fungi did not occur in the jar tests, one can only conclude that some 
_ factor was unfavorable to their best development in the series of 


s 
74 BULLETIN 1298, U. S. DEPARTMENT OF AGRICULTURE 


experiments reported. As in the case of molds, some of the hymeno- 
mycetes have been observed to cause much more damage under 
normal conditions of storage than they did in pure culture tests. 
Among the factors contributing to this reduced activity of the 
fungi in certain of the artificial cultures, both temperature and mois- 
ture doubtless play an important part. No one temperature would 
be the one most favorable for the maximum growth of all the 54 
species tested. The temperature of 21° C., at which the cultures 
were stored, would be too low for the most vigorous growth of many 
of them. Laboratory temperature (approximately 22 to 28° C.) 
appeared to be better. (See Pl. XIX, a 2 and 3.) The moisture 
requirements may also vary greatly for the different fungi. (See 


- 


Perret rset 
aN 
XN 
: 
i) 
3 
% 
A) 
\ 
ie 
oN 


Pt re ae Ne 
Pe ee sh ee A EN el 


[ORS SESE S| 
ai aa naa GaSe, 


Weigh? loss — per cenr 
~ 
Le) 


> 
i) 
© 
Q 
% 
5 
0) 
N 
iN) 


eee Pe 
Naat 

SH 

fai 

a 

fal 

ER 

ai 

fh 


om ) 

1622? | 5454 Yo 

a TT 

———— m=o20/9,", | |_| 1 
9 


6 


a el ee te te ee ae eo 


ae 


Time — rnorths 


Fig. 3.—Graphs showing loss in weight of ground-wood pulp due to pure cultures of two wood-destroying 
fungi under two different moisture conditions ey 


fig. 3.) In some of the jars the pulp evidently became either too dry 
or too wet for the maximum growth of the fungi. (Refer to Table 
14 for pronounced variations in moisture content.) Meta" 


CHEMICAL PROPERTIES 4 


It has been demonstrated that the growth of the organisms of 


decay in wood pulp is accompanied in most cases by a loss in weight 
of the pulp. From data available in the technical literature (22) 
it is evident that under the action of these organisms the complex 


wood substance is broken down into simpler compounds, some of 


which are water-soluble and some of which pass ‘off as gases. With 
this in mind, a study was made to determine the changes in the chemi- 


» 


¥ 


~—P 


—— =": ws Se ee 


CONTROL OF DECAY IN PULP AND PULP WooD 75 


cal properties of some of the ground-wood pulps the physical proper- 
ties of which have just been discussed. (See Tables 14, 15, and 16.) 
The changes that accompany the action of molds and of wood-destroy- 
ing fungi appear to be different, in degree, at least, if not in kind. 


EFFECT OF MOLDS 


In Table 17 are presented the results of the chemical analyses of 
ground-wood pulps inoculated with 26 molds in pure culture and 
subjected to storage for periods of 6, 9, and 12 months. The loss 
in weight is also shown. The data in all cases are calculated on the 
basis of the original dry weights of the samples taken. 


TABLE 17.—Chemical analyses of ground-wood pulp deteriorated by pure cultures 


of molds 
Sodi- 
Incu- Orig- | Cold | Hot | po Cell 
Sample No. | bation Organism or culture No. inal | water | water Grae: Lignin 1 aS 
period loss_|soluble| soluble} “; 76 os 
soluble 


Months cent cent cent cent cent cent 
ES SS SSIS SE) ES See ee ee ee ee Se ee 0.0 0.0 1.0 105% 29. 7 60. 0 
92)-—4--1- == 6 2 1.6) 14.7) 28.4 59.0 
> 2. ae yD oe ee ee ee ee 1.2 .8 2.1| 12.9] 28.2 58. 4 
8. > on ee ae 1 1.0 1.8 4.4 14 4] 29.0 58.0 
26 a 6 ll 7: 1. : 12] 14.5] 28.5 57.8 
— * 12 | Clromuces sp____---.-------- 7b — vor) g-4-|+- 14.4 b= 90.9 57.7 
“. 6S aie 6 0.7 1.8 2.8| 14.8] 29.0 60.0 
iO ae See Ae 9 |} Penicillium purpurogenum -_ 1.6 1.0 1.9 13.7 28.5 57.4 
|, as ie a 12 1.5 9 341) 15.51 20% 58. 8 
os ie ik ca ae 6 14 ae 95 |) 14:31 Boak 57.6 
8» ee yemegme Sepa pape D> Cttromyces sp seh ee nc oe = 1.9 1.4 Deal: 14.3 28.5 57.1 
87 2 at ae 12 6 Lt 4.4| 13.0] 29.1 B7.7 
er om ae 6 + (3 6 1.3] 14.2] 29.2 58.5 
es ie aa 12 |f82219-2-..------------------- 14 “Ui | 324) 1804. BOS 56.8 
— 6 1.2 8 1.8| 127] 28.5 57.3 
S31. 1. BU Peo.  Noren mea» 1.8 0 14411 184) 97,9 58.3 
a! eT 12 1.9 :0 3.0| 12.5| 29.5 56.6 
in) 6 1.5 ‘8 -0| 10.9] 29.0 58.2 
) 1 Siar Si a i CE STS a ee ee ee ee 1.9 1.5 2.1 | 13.0] 29.1 56. 8 
117 eee, yoda: ooahe ak 12 £3 1.5 3. 1 13,9 130-5 57.5 
[ae Sie oe a £4 1.2 : 10.6| 29.0 59.2 
120 PA ee ns 12 \so219-21 suitiiiaaaiienatea { 10! 20} 32} 146! 30.1 57.2 
(1 Sheed eal 6 z be ha ‘9 1.8] 11.4] 29.0 57.9 
At Os Baa g | f82219-18--------------------- { 16 '5| 28| 13.2] 99.1 55. 4 
Msc} 9 fPapulospora migra. \ tel i7| 41| aa| d00| S00 
acces € I Pei coon {rr} ig) ka) may mal gre 
oo OG ok ie aa ieee 6 12 2.2} 14.5| 29.1 56.7 
ae 9 \ Gliocladium SP-------------- { 4] 13) 33 143] a3) S86 
rrssatos 5 |. a ? ; 3 12.7| 28.4 59.7 
46 Li Sa : \ spicaria gt sa agar { 1.4 3 2.9 13 5| 29.7 56. 0 
=. a ees ; 5 7), 43.3] 28-7 56.6 
92. ey. : \p enicillium sp_..------------ { 1.8 1.5 8 3146 5 28. 5 56. 1 
race ees i . ee ane 7 57.0 
— 10 \10918~7 Sa aianaaaisiiaiieatae { 14/ 30] 38] i127} 29:0| 574 
tee Gee tee GiNSISISSIA eo Te ee eyes .9 42 2.0 12.9 28.1 57.3 
SS a \ Penicillium pease t i ute { Gy Bilis batho eee pratt cceee 

te eteheiaaian eed din am, doo wo ton wn. . . '. e ad. (. 
ee Gi |) IND1S 4». 2 ee eee 8 Sy 18} 15.1} 29.2 57.5 
6 | Trichoderma sp...__--_-----. 3 8 LS 113.3, $28.6 58. 0 
Vel i ae 6 |) Allernor spss ee .9 .6 1.6 13.6 28.8 57.5 
eo TS ear aa ae A 11 1.8] 13.3| 28.9 58.5 
Shiri eres 2 o.- G.|, Erichoderma:spec teen .4 1.6 py 14.0 28. 8 57.6 
eS eee ae 6 | Afticon sp 3282 5 a eee ee 9 1.5 27 13. 5 28. 4 56. 7 
gel ae ee 6 eme-6eycii sy Sinn 1.2 1.4 1.1] 11.4] 29.0 58.6 
122._- el 2 ee @ |. iaicor spi. = es eee ad 1.6 .9 .0 10. 4 29. 4 58. 5 


76 BULLETIN 1298, U. S. DEPARTMENT OF AGRICULTURE 


A comparison of these data with the data for sound pulp shown in’ 
the same table indicates that only small changes were produced. 


The loss in weight in no case exceeded 2 per cent, and the increase 
in solubility in cold water, hot water, and sodium hydroxide did not 
exceed 3 per cent, 3.5 per cent, and 6.5 per cent, respectively. In 


only one case was the loss in cellulose greater than 4 ae cent.. The 


slow rate of deterioration is evident from the typical set of curves, 
Figure4. The 10 per cent loss in the case of Papulospora nigra is not 


excessive nor indicative of far-reaching decomposition; it approaches 


- 


MRREEERe. 

cop SS eee EEL 
Lie. cee ie 

Ter RIA Gaia wines 

bE ie eae 

eee 

< 

Seat terie tt eel 

Sa A sad OT sl 

t eee 

SC ee ete 

Sse CECE 

R oofted Le be eee 

a Fe ES OR Ge 

oe Cm Ee eG 

Sd EE 

Sra ih uae aa 

© a ia 

1 Se 

8 Coeeestoree 
CE atesgens vars me 
PEELE ELELELLE [ole ween soluble 
Ee = 


—<$—<—— TS TT 


Time — months 


Fic. 4.—Graphs showing analytical constants of gronnd-waod pulp infectea with a mold culture, No. 
1091 


in value, however, some of the losses due to some wood destroyers, 


which is to be expected since Papulospora nigra is closely related to 
the hymenomycetes. me! 


EFFECT OF WOOD-DESTROYING FUNGI 


That the action of wood-destroying fungi on the chemical on 
nents of ground-wood pulp is more vigorous then that of molds, 
will be seen from a study of Table 18 in which are set forth the chemical 


data for one sound ground-wood pulp, and ground-wood pulps — 


inoculated with 21 of these fungi. 


CONTROL OF DECAY IN PULP AND PULP WOOD Th 


TaBLe 18.—Chemical analyses of ground-wood pulp deteriorated by pure cultures 
of hymenomycetes 


Incu- Orig- | Cold | Hot scat Cellu- 
Sample No. | bation Organism or culture No. inal | water | water dkovide Lignin ite 
period loss | soluble | soluble | <i ible 

Months Per cent| Per cent| Per cent| Per cent| Per cent| Per cent 
ae aie an AMR aR lu Seal aed cama a 0.0 1.0 10.1 29. 7 60. 0 
5 18.1 4.9 9.0 37.8 28. 8 35.5 
Die 2 Ss OM Seo hO— Toi... ua 2 eee eS 7A ae | 5.9 10.5 37.6 28. 4 33. 4 
FA perry celts ik 26.3 6. 4 11.3 38. 3 28. 8 27.8 
7). Se hoes ee See 6 4620-2 2¢. 8.0 13. 0 40. 0 VA if 26.8 
1): pe spore sateen 17 qy hoa gare olga hniet ee cate ihe sti pale 49, 4 7.3 11.0 33. 4 26. 6 10.8 
i. (2 = aa 6 22. 2 9.5 1367 40. 7 30. 7 29. 0 
i|; Ce eee TD) SRD | Ces I GIR GN PRES See oe 33. 1 iG ee 15. 2 41.6 28. 8 18. 2 
ul: (ie we ee 12 38. 6 9.1 13. 0 38. 0 28. 5 16.9 
1: OE a plea SE 6 }61020-1 { 11.5 3.9 %2 30. 9 29.1 40. 6 
|): ae oon Ot fees ho aaea po saasgesses sas = ; : j e ; 2 5 29. 5 36.9 
i. J 2 oe 6 I . . 29.6 30. 6 44,2 
rc Gat Aas ane eae 9 \p omes TOseus..-------------- { 9) 82) G1) m2) 307) 441 
1S Ue ae ae 6 : Pet 13.5 : 34.9 27. 40. 4 
“Deas ea aa g |fPeniophora tabacina_- --.---- { 19.4) 4.9 7.9} 37.2} 320| 35.1 
iL). 3 ee 6 4620-3 { 14.1 6. 0 9.8 33. 0 29.3 38. 0 
li; 2 2 ee SO) SIS GR asi Sia ee meer ace ae ba f : : ; W - > : 29. 4 37.3 
li) a ee Tees ea 6 . : t : 29. 48.8 
cy a eran 9 }o1420-7 nono nnn nanensn nnn =n--- { 28| 3) 85] 402] 346) 380 
i SS 6 : . 21. : ahi 41. 28, 32.0 
Se ie aa g |sLentinus lepideus.._-------.- { 30.3| 9.6| 157| 40.5] 28.6| 24.2 
fae Se 6 4.1 23 5.4 21.0 26. 8 56. 0 
io ee Se eee es UN oA A ae ee oe 5.6 2. 1 6.0 19.7 Diy 54. 7 
(J SS a) ee ae 12 if ‘ 3. 2 if ; 216 26. 6 53. 4 
Viet Le 2 tt 6 : 2. H 14.1 29. 4 56. 7 
mt aos g (\102019-1a_------------------- { 23| 1.9| 35] 13.8] 291|. 58.0 
SL) SS a ae 6 1.9 0.0 1.6 13. 6 28.7 55.6 
Si) 2 ee eee ae 9 |, Paxillus panuoides_________- 2.8 0. 6 5.0 14. 4 28. 4 55.8 
BA gsc pee pene aes 12 3: : . : 4 17.8 eT ! 55.9 
ct) ES 6 ibs ; ) 13.0 28. 57.6 
(aa) Soe 9 \roo1s 10.------+------=------ { C7) Ow te 0 120B I G70 
iit! eee Gee Ses Gi ipotoeOte ses er 2.0 1.5 35:2 13.9 29. 4 57.4 
apeeee oo ae ke 6 \61 420-3 { 8.6 5.0 7.8 30. 6 29.3 45.1 
Ls) en ee ee PLA DS a lie Rate gi pie Sa igs? ed 13.9 5.9 10. 0 Sileeds 29. 2 38. 3 
1: EAS Bubs aie 6 | Corticitum galactinum______-_- 2° 1. 1.4 2.9 15. 8 28. 4 57.2 
Ce) oe ee 6 \52000-1 { BL j> Ld) 23). 5) 24) 57.7 
Eo) On ae ee SL eeaio| . wey ea 4.1 2.2 3.9 19.5 32.0 56. 0 
c(G jae Cas Gaegnes: mil (Det PA es en ile ee meer eae, Mae Ba 2k TZ 3.0 ie 1 28.9 55.8 
7 oe eee 6 N\eq00-4 { 8.3] 23] 36] 15.8) 288] 56.4 
1 eae eek aes Saeed WSS Ror las es Gale sas War Se 5. 1 pati 1 Rea 22.0 21,2 53. 8 
Jf SS 6 |\ 4600-4 { eA TN et BRL BL) WZ 27.k | 754. 8 
ile i Se a uw jl. SR ee Fea as ere a Bre ees 5.0 Pai 4,7 20. 8 26. 9 54.6 
it) SO ee 2 ee DERG sue Re eR ee 0.8 1.9 21 14, 2 29.1 50. 5 


The large losses in weight, which with one fungus reached 27.1 per 
cent in six months and 49.5 per cent in 12 months, were reflected in the 
chemical data. The solubility in cold and hot water and in sodium 
hydroxide in practically all cases increased very substantially, and 
reached maxima of 11.1 per cent, 14.7 per cent, and 40 per cent, 
respectively. The decreases in cellulose content were also very 
marked. The reduction in one case was 10.9 per cent. 

In striking contrast with the other chemical data is the fact that 
the lignin content remained practically constant and independent of 
decay. Its variations from the value of sound pulp were not much 
greater than the experimental error. The action of the fungi investi- 
gated was, therefore, apparently selective in that it did not involve to 
any appreciable extent of decomposition of lignin. Unfortunately it 
was the cellulose, which from the papver-making standpoint is the 
most important part of the wood, which suffered the greatest deterio- 
ration. 


78 BULLETIN 1298, U. S. DEPARTMENT OF AGRICULTURE 


Fomes roseus, Peniophora tabacina, and cultures 82219-15, 4620-2, 
4620-1, 61020-1, and 4620-3, acted rapidly during the first six 
months of storage, as is indicated by the great changes recorded. 
After six months the rate of change decreased very noticeably. This 
is evident from the curves shown in Figure 5, which are typical of 


these cultures. The decrease in rate of deterioration may be ac- 


counted for in one or all of the following three ways: 
1. There may be a decrease in the vitality of the organism, due 
perhaps to autointoxication. 


S 


Sy] 
S 


v, 


ty 
Paes bal deg 
NS sa Pa ad 
aN asa 
t EL Ee 
eer ke bay pad 
ad bal aed 
. ao arte 
SI GTScAVERG 
WIEKEH SK Gh Cm 
Pa Acc em Gs sk 
2 ECS ENA 
§ FOOT 
5 sed CCE EES 
eee GG he Be as Bi BS ions & 
ee etait 
8 LEC Para 
pt ded tele | ee ek aes 
SEER 2a SH AB Ae 
AS 8 2 Ge aa es o— 
© é 
og we 
po he ie 
TE a 
fe) 6 2 


Time —montAs 


Fig. 5.—Graphs showing analytical constants of ground-wood pulp infected with a hymenomcete cul- 
ture, N. 4620-2 . 


2. The cellulose which remains after a certain period may not be 
available to the fungus. Assuming that the fungus uses the more 
accessible cellulose, leaving the lignin, the remaining cellulose in the 
ligno-cellulose complex may be more or less encrusted with pure 
lignin and so protected, to a certain extent, against further wh cts 


own. 

3. The cellulose in the cell walls of the fungus, although somewhat — 
different from ordinary cellulose, may cause a slight increase in the 
cellulose determination. 


(7) 


(8) 


- CONTROL OF DECAY IN PULP AND PULP WOOD 79 


BIBLIOGRAPHY 


.ACREE, S. F. 


1919. Destruction of wood and ee by fungi and bacteria. Jn Pulp 

and Paper Magazine of Canada, v. 17, pp. 569-571, July. 
BarRNES, FREDERICK. 

1920. Mold growths on wood pulp. Jn Pulp and Paper Magazine of 

Canada, v. 18, pp. 995-996, Sept. 23. 
Bates, J. 8. 

1921. Studies in the use of rotten wood and the prevention of decay in 
pulp. Jn Pulp and Paper Magazine of Canada, June 9 and 30, 
Aug. 18. 

BEADLE, CiayTon, and Stevens, H. P. 

1909. Diseases in pulp wood and pulp. Jn Paper Worker and British 
Trade Journal, November, 1909; reviewed in Paper Trade Jour- 
nal, v. 49, pp. 42, 46, 48, 54, Dec. 2. 

Buair, R. J. 

1920. Decay in pulp wood—deterioration in pulp. Jn The Paper In- 

dustry, v. 2, pp. 95-96, Apr. 
Buair, R. J. 

1922. Molding of chemical wood pulp with suggestions as to control. 
In Pulp and Paper Magazine of Canada, v. 20, pp. 429-431, 
May 25. 

Buarr, R. J., and PARKE-CAMERON E. 
1922. The use of clean water as a preservative for storing mechanical 
pulp. Jn Pulp and Paper Magazine of Canada, v. 20, pp. 64—- 
67, Jan. 26. 
Buromsky, J. 

1912-1913. Die Salze Zn, Mg, und Ca, K und Na und ihr Einfluss auf 
die Entwicklung von Aspergillus niger. (The Salts of Zn, Mg, 
and Ca, K and Na and their influence on the development of 
Aspergillus niger.) In Centralblatt fir Bakteriologie, Abt. 2, 
Bd. 36, pp. 54-66. 


(9) Hartia, R. 


(10) 


an 


(12) 


(13) 


(14) 


(14) 


(16) 


(7) 


moxie, Fy. 


1894. The diseases of trees. Translated by William Somerville and 
H. Marshall Ward. 


1920. Log piles. Their hazards and protection. Growth of fungus and 
quality of pulp. Jn Quarterly of National Fire Protection 

Assn. v. 14, pp. 81-94. 

Hoxtr, F. J. 

1920. Pulpwood storage. Prevention of fire and methods of protection. 
Inspection Department, Associated Factory Mutual Fire Insur- 
ance Cos., 48 pp. ; 

Hoxm, F. J. 
1921. Fire prevention in pulpwood by means of artificial fog. In Pulp 
and Paper Magazine of Canada, v. 19, pp. 5-7, 37, 39, Jan. 6, 13. 
ITERsoN, GEeRRIT VAN, Jr. 

1904. Die Zersetzung von cellulose durch aerébe Mikroorganismen. 
(The decomposition of cellulose by aer6ébic microorganisms.) 
In Centralblatt fiir Bakteriologie, Abt. 2, 11, pp. 689-698, 1 pl. 

Kiem, PAavt. 

1896. Das Verderben feuchten Holzschliffs (The deterioration of moist 
groundwood.) Jn Papier Zeitung. v. 22, pp. 1167, 1168, 1207, 
1208, 1243, 1244, 1274, 1275, 1311, 1312. 

LAGERBERG, TORSTEN. 

1920. Rd6otskador i lagrad pappersved (Damages from rot in stored pulp- 

wood.) In Skogsvardsforeningens Tidskrift, Hafte 7-8, pp. 149- 


167. 
McBerts, I. G., and Scatzs, F. M. 

1913. The destruction of cellulose by bacteria and filamentous fungi. 
U.S. Dept. Agr., Bur. Plant Industry Bul. No. 266, 52 pp., 4 pls. 

MITSCHERLICH, E. 

1850. Zusammensetzung der Wand der Pflanzenzelle. (Composition of 
plant cell walls.) Bericht tiber die zur Bekanntmachung geeig- 
neten Verhandlungen der K6niglichen Preusischen Akademie der 
oer zu Berlin, pp. 102-110. Cited by McBeth and 

cales. 


80 


(18) 


(19) 


(20) 


(21) 


(22) 


(23) 


(24) 


(26) 


(26) 


(27) 


(28 


BULLETIN 1298, U. S. ne ee OF AGRICULTURE 


Moreau, FERNAND. 

1918. Sur le blanchiment des pates a papier E Celnchee par des myceliums 
de champignons. (Concerning the bleaching of paper pulp colored 
by the mycelium of fungi.) Jn Bulletin Trimestriel, Société 
Mycologique de France, v. 34, pp. 29-30. 

Munro, W. A. 

1920. Storage of pulpwood and wood pulp. Jn The Paper Industry, v. 2, 
pp. 841-842, Sept. 

Pierson, A. H., and Rryno.ps, By Vs 

1921. Pulpwood consumption and pulpwood production, 1920. U. S&S. 
Forest Service in’ cooperation with American Paper and as: 


Assn., 39 pp. 
Page Cb. 
1907. Report of State Botanist. Bulletin of New York State ‘if cclemn, 
v. 116, p. 36 


Ross, R. E., and Lissr, M. W. 

1917. The chemistry of wood decay. Jn Journal of Industrial and 

Engineering Chemistry, v. 9, p. 284, March. 
S£z, ‘Prerre. 

1917. The molds that injure paper. Jn Scientific American Supplement, 

No. 2159, May 19. 
Ste, PIERRE. 

1919. Les maladies du papier piqué. Les champignons chromogénes 
qui les provoquent. Les modes de préservation. (The diseases 
of spotted paper. The chromogenic fungi producing them. 
Modes of preservation.) 168 pp., 17 pls., O. Doin et Fils, 

. Editeurs, Paris. - 
SNELL, W. H. 

1921. Relation of moisture contents of wood tu its decay. Jn Paper, v 

28, pp. 22-24, May 4. 
THuom, CHARLES. 


1910. Cultural studies of species of Penicillium. U.S. Dept. Agri., Bur. = 


Animal Industry Bul. No. 118, 109 pp., illustrated. 
WoOLESKY, FERDINAND. 
1896. Aufbewahrung von feuchten Holzschliff. (Preservation of moist 
groundwood.) Jn Papier Zeitung, v. 21, p. 563. 


) ZELLER, S. 


1920. Humidity i in relation to moisture imbibition by wood and to spore 
germination on wood. Jn Annals Missouri Botanical Garden, 
v. 7, pp. 51-74. { 


ADDITIONAL COPIES 
OF THIS PUBLICATION MAY BE PROCURED FROM 
THE SUPERINTENDENT OF DOCUMENTS 
GOVERNMENT PRINTING OFFICE 
WASHINGTON, D. C. 
AT 


25 CENTS PER COPY 
V 


Le oe ee eae 


Rae ,-2 el aimed 


Pattee 
(S06 RoR 
ts 6. ae 


Pe 
ra 


NE Re 
Do! let} 


wei 
HT oh 


UNIVERSITY OF TORONTO |) 


CKsoptouyed 4yser0F uo suT,eTtng2 
JO yYUem{Qaedegq SaanqTnoTasy 


L996£S 


as 


“stp | 


) 


oog* Aor | 


y 


| zo €O St St oLee 
9 WALI SOd 4THS AVE FONVH G 


MAIASNMOQ LV TLN