SENATE

LETTER FROM THE
SECRETARY OF AGRICULTURE

TRANSMITTING

IN RESPONSE TO SENATE RESOLUTION

OF APRIL 30, 1912, INFORMATION RELA-

TIVE TO THE STUDY AND INVESTIGA-

TION OF THE SO-CALLED CHESTNUT
; TREE BLIGHT

i [ay oe. 1912.—Referred to the Committee on Agriculture and Forestry
and ordered to be printed with illustrations

WASHINGTON

eas

A <<

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CHESTNUT TREE BLIGHT.

° DEPARTMENT OF. AGRICULTURE,

OFFICE OF THE SECRETARY,
Washington, May 8, 1912.
The PRESIDENT OF THE SENATE.

Sir: In accordance with the resolution of the Senate, under date
of April 30, directing that the Secretary of Agriculture “submit to
the Senate, at the earliest practicable day, the results thus far se-
cured in the study and investigation of the so-called chestnut-tree
blight, and the amount of money thus far expended in said study
and investigation,” I have the honor to report as follows:

Observations on the disease known as the chestnut-tree blight,
or the chestnut-bark disease, were begun in this department in the
summer of 1907, as soon as any office was organized to do this class
of work. The results secured in the study and investigation of this
disease have been set forth in detail from time to time in the follow-
ing publications, which are inclosed herewith, and constitute a part
of this report:

Bureau of Plant Industry Bulletin No. 121, Part VI, The Immunity of the Japanese
Chestnut to the Bark Disease, February 10, 1908.

Forest Service, unnumbered circular: Extent and Importance of the Chestnut
Bark Disease, October 21, 1908.

Bureau of Plant Industry Bulletin No. 141, Part V, The Present Status of the Chest-
nut Bark Disease, August 30, 1909.

Farmers’ Bulletin No. 467, The Control of the Chestnut Bark Disease, October 28, 1911.

A series of 34 photographs, mounted on 20 sheets, with explana-
tory legends, illustrating various hases of the disease, are also
appended, and constitute a part of this report. (Pls. I-X VL.)

A summary of results follows:

(1) The disease is caused by a parasitic fungus which kills the
tree by girdling it at various points. Trees of all ages and condi-
tions are attacked without discrimination.

(2) A tree once attacked never recovers. It takes from two
months to four years to kill a tree, according to the size of the tree
and the point of attack. The average length of life of a diseased
tree is three years. Trees killed by this disease sprout readily from
the trunks and roots, but the sprouts are in turn infected and killed.

(3) All species and varieties of chestnut now grown in this coun-
try are subject to the disease, except the Japanese and Korean
varieties, which are resistant. The Japanese and Korean chestnuts
are small trees, fair nut producers, but probably valueless for tim-
per. No other species of trees have as yet been parasitized by the
fungus, but it is not impossible that other species, such as oaks and
walnuts, may later become attacked.

(4) The disease is spread by the spores of the fungus, which are
sticky in character. They are probably not diffused by wind to any
appreciable extent, but are spread by rain, insects, probably also by
birds, small mammals such as squirrels, and by man. Unbarked
timber and cordwood from diseased trees and diseased chestnut

3

4 CHESTNUT TREE BLIGHT.

nursery stock may carry the disease bodily for great distances. The
majority of infections take place through wounds made by bark-
borers. The relation of insects to the disease appears to be very
intimate.

(5) The origin of the disease is unknown. Its obvious spread
from a center—the vicinity of New York City—suggests that it is
not a native disease; and the resistance of Asiatic species of chestitut
. to the disease suggests that it may have been imported from Asia
with the Japanese chestnut. No evidence has been secured to
connect the considerable losses of chestnut timber in the Southeastern
States in past years with this disease; these losses were more probably
due to attacks of insects. ;

(6) The disease was first called to public attention in 1904, but
it probably had already been present on Long Island for some years.

(7) The value of the chestnut stand is variously estimated at
between three hundred and four hundred million dollars. This
disease has already caused ‘an estimated minimum damage of
$25,000,000. :

(8) Judging by the history of the disease to date, it may be expected
to spread throughout the range of the chestnut tree during the next
two years, unless checked by human effort. Whatever is done to
control the disease by any methods known at present must be
attempted immediately, else the disease will be beyond control by
any effort ever likely to be put forth.

(9) As shown on the accompanying map (PI. I), the disease is now
known to occur in at least 10 States, viz: Massachusetts, Rhode Island,
Connecticut, New York, New Jersey, Pennsylvania, Delaware, Mary-
land, West Virginia, and Virginia. In all of Connecticut, New Jersey,
and Delaware, and in western Massachusetts, eastern New York,
eastern Pennsylvania, and northeastern Maryland, the chestnut trees
are already generally infected, and a large per cent are already dead.

(10) Outside of this area of general infection the disease occurs at
scattered points (‘‘advance infections’). These consist mostly of
single infected trees, or small groups of trees, often many miles apart.

(11) Analogy with pear blight and peach yellows and with animal
and human diseases that are controlled by destruction or isolation of
the foci of infection suggests early destruction of the advance infec-
tions as the only possible means of controlling the disease or limiting
itsrange. There is no contagious disease known that does not yield
to sanitation and quarantine. The destruction of diseased trees can
not possibly be an effective means of control, however, in localities
where the disease has already become general.

This method of destroying advance infections has been employed
extensively by private owners to check the progress of the disease
in their own holdings. But since general cooperation is necessary
to make any sanitation finally effective, it appears necessary to
organize private effort under State control. This has already been
done in Pennsylvania under special law, and is about to be done in
Virginia under special law; and under the general laws now existing,
in West Virginia and probably some other States. This department
indorses the work of these States, and particularly the early and
vigorous action of Pennsylvania. .

(12) Results to date indicate the following lines of activity as
desirable and necessary to be carried out by this department and
the various States in cooperation:

CHESTNUT TREE BLIGHT. 5

(a) The determining of the exact range of the disease, and the
locating and cutting out of all advance infections. This work to be
done in Virginia, West Virginia, western and probably southern Mary-
land, Ohio, western Pennsylvania, central and western New York;
possibly also in Kentucky, Tennessee, and North Carolina, following
the methods now employed by the Chestnut Blight Commission of
Pennsylvania. In all localities, and particularly in those States
where no State quarantine of any sort is contemplated, it will be
necessary to instruct private owners regarding the disease in order °
that they may take such measures as they see fit to protect their own
property.

(b) The careful inspection of all nurseries containing chestnut
trees, and all chestnut nursery stock.

(c) Determining by extensive local investigation the best methods
of rapidly utilizing and marketing the timber of trees dying and dead
from this disease, in order to protect timber owners against total
loss, and to reduce infection. This work to be done in all localities
where infection is already general.

(dq) Determining what changes in general forest management are
necessary in those localities where the chestnut tree is already doomed,
and so far as practicable putting such changes immediately into
practice.

(e) Continuing experiments on tree surgery and tree medication,
in the hepe of saving valuable orchard and ornamental trees. Any
positive results from this line of work will also be applicable to other
tree diseases, including those of fruit trees.

(f) Continuing search for a resistant American stock, and breeding
from resistant Asiatic stock, m order particularly to rehabilitate the
chestnut-orchard industry; at the same time breeding also for timber
trees. Results of the greatest value to the chestnut-orchard industry
can, not fail to be secured from this line of work.

(g) Making careful studies of the many unsolved scientific problems
involved in the disease. Some of the more important of these are:
The relation of the disease to climate; the relation of the parasite to
the varying tannin content of the tree; the origin of the disease; the
relation of birds and insects to the distribution of the disease; the
nature and degree of resistance in the Asiatic varieties.

(hk) Determining in detail the relation of the disease to the future
of the chestnut timber in the proposed Appalachian Forest Reserves,
and making special effort to keep the disease out of this territory.

With the exception of about $400, expended by the Forest Service
in 1908 in the work set forth in the inclosed circular by E. R. Hodson,
all expenditures have been made in the Bureau of Plant Industry.
The amount thus far expended in this study and investigation is
$14,885.96 (estimated), which is itemized as follows:

For the fiscal year ending June 30, 1908 (estimated)......-.....-.-..-.---- $350. 00
Hon ewe tines. vear endime sune 30) 1909). 2. 2 sleet 22 eee be nk 2 Sees 1, 365. 81
ocwimMerniscal year ending Jume sON TOON 2.0.52. decice. cece cen cee s, dl, SIA 27
Hiorinenses| yearmending sume! 30); 19s 225025250. okt ane ee ae ose 2, 210. 51
Bar tue fseal year 19125 to date (estimated)....--..-..--------:------1+-2 9, 145. 37

sith es eee See AL ROSES. if See ins So Ce ee ae 14, 885. 96

I have the honor to be, sir, your obedient servant,
JAMES Wison, Secretary.

[Reprint of Bureau of Plant Industry Bulletin No. 121, Pt. VI, issued Feb. 10, 1908.]

THE IMMUNITY OF THE JAPANESE CHESTNUT TO THE BARK
DISEASE.

By Haven Mercatr, Pathologist in Charge of the Laboratory of Forest Pathology.

THe EXTENT OF THE BARK DISEASE.

The bark disease of the chestnut, caused by the fungus Diaporthe
parasitica Murrill, has spread rapidly from Long Island, where it was
first observed, and is now reported from Connecticut, Massachusetts,
Vermont, New York as far north as Poughkeepsie, New Jersey, Penn-
sylvania, and possibly Delaware. It is no exaggeration to say that it
is at present the most threatening forest-tree disease in America.
Unless something now unforeseen occurs to check its spread the com-
plete destruction of the chestnut orchards and forests of the country,
or at least of the Atlantic States, is only a question of a few years’ time.

AN IMMUNE VARIETY.

Observations made by the writer during the past year indicate that
all varieties and species of the genus Castanea are subject to the dis-
ease except the Japanese varieties (Castanea crenata Sieb. and Zuec.).
All of Siena that have been observed in the field or tested by inocu-
lations have been found immune. This fact can hardly fail to be of
fundamental importance to the future of chestnut nut culture.
Although the nuts are distinctly inferior in flavor to the European
varieties, such as Paragon, the Japanese chestnut is already grown
on a large scale as a nut-producing tree. There are, however, many
trade varieties of dubious origin. Some of these may prove later to be
subject to the disease. Immunity tests of all known varieties of chest-
nuts have been undertaken.

Attempts will also be made to hybridize the Japanese with American
and European varieties, with the hope of combining the immunity of
the former with the desirable qualities of the latter.

However excellent as a nut and ornamental tree, the value of the
Japanese chestnut as a forest tree is doubtful. It can be recom-
mended only experimentally at present for forest planting. It cer-
tainly will not take the place of the American chestnut. The tree is
said to attain a height of 50 or 60 feet in Japan. As seen in this coun-
try, it is a handsome tree, dwarfish and compact in habit, and rather
slow growing. It has hardly had time to show how large it can grow.

The immunity of the Japanese chestnut, together with the fact that
it was first introduced and cultivated on Long Island and in the very
locality from which the disease appears to have spread, suggests the
interesting hypothesis that the disease was introduced from Japan.
So far, however, no facts have been adduced to substantiate this view.

6

[Reprint of Forest Service unnumbered circular, issued Oct. 21, 1908.]

EXTENT AND IMPORTANCE OF THE CHESTNUT BARK
DISEASE.

By E. R. Hopson.

INTRODUCTION.

Three years ago a destructive fungous disease of the chestnut first
attracted attention and almost immediately assumed the character
of an epidemic. It seems to be one of the most serious diseases
which has ever attacked an American forest tree, and has done great
damage locally in and around New York City, and is now spreading
rapidly in all directions to forest tracts in Connecticut, New York,
New Jersey, and even into Pennsylvania.

The disease was first studied by Dr. W. A. Murrill, of New York,
and during the past 18 months it has been under investigation by
Dr. Haven Metcalf, of the Bureau of Plant Industry. The tech-
nical details given in this circular have been derived chiefly from the
publications of the former and information supplied by the latter.

MANNER OF INFECTION.

The disease is caused by a fungus known as Diaporthe parasitica
or Valsonectria parasitica, the spores of which enter the tree through
wounds on branches or trunk. Dead twigs also offer a means of
entrance, and there are probably other ways, not yet known, by
which the trees become infected.

From the point of entrance the fungus spreads in all directions
throughout the cambium and inner bark until it completely girdles
the branch or trunk it has attacked. It has been found that a few
of the outer annual rings of the wood are also attacked, and it is very
likely that the fungus penetrates some of the medullary rays in
search of the food material which they contain; but the real seat of
the injury is the inner bark and the growing layer of the wood.

SYMPTOMS.

When a tree is first attacked the disease is not noticeable, and is
likely to be overlooked. In many instances the trees are attacked
first on the smaller branches. These are soon girdled, and the foliage
turns yellow and then wilts. By these wilted branches the disease
can be detected from a distance. The girdled branches or trees do not
usually die until the second year, except when they are attacked
very early in the season, or when the infected limbs are small.

On limbs with smooth bark the diseased patches are sunken and
discolored, with small brownish or yellow knobs scattered over the

7

8 CHESTNUT TREE BLIGHT.

surface. On the edge of the affected area in the growing season
there is a ring of greenish, yellowish, or bright yellow excrescences
which resemble horns and are very conspicuous, so that ingyoung
trees the disease is easily detected even before the branches wilt. In
very dry weather, however, these horns may be nearly or entirely
suppressed. Where the bark is thick, as on large trees, it is not
changed in appearance, but the brownish knobs of the fruiting bodies
show in the cracks, and the bark sounds hollow when struck.

On account of its rapid action in killing or wilting small branches,
the disease can not remain long undetected if the trees are under
inspection. At the end of a single year the disease has usually made
its presence conspicuous by a large number of dead and dying trees.

LocaLities AFFECTED.

In 1905 the disease had already spread over a considerable area
around New York City, where it apparently originated. In the
present year it is spreading rapidly in a westerly direction over
northern New Jersey, where in Morris County large tracts have
recently been attacked. New York City is about the center of the
infected area. Last year the chestnut tracts in Westchester and
Nassau Counties in New York, Fairfield County in Connecticut, and
Bergen County in New Jersey were severely attacked, and now Morris
Essex, and Monmouth Counties, N. J., can be added.

In Connecticut the disease is very severe at Stamford. It has been
found near Danbury and Waterbury, and is known to extend along
the coast to New London. It is also reported in southeastern Massa-
chusetts and as far north as Wellesley.

On Long Island it is common in the western part and along the
northern shore to Huntington. It is likely that it occurs on the
island wherever there is chestnut, although it has not yet been
reported from the easternend. It extends up the Hudson to Pough-
keepsie, and across the river to the west; it has been found, though
not in great abundance, at Turner and Warwick, and has been
reported at Marlborough. Near the Connecticut line it occurs as
far north as Pawling and is very destructive from Katonah all the
way southward to New York City.

In New Jersey the disease is very abundant in the northern and
eastern parts, particularly near the coast in Bergen, Essex, and
Monmouth Counties. Southward it is found along the Delaware
River to Trenton, and abundantly along the coast near Chapel Hill
and Eatontown in the northern part of Monmouth County. Recently
a belt around Morristown and German Valley has become badly
infected, and the disease has been discovered in wild trees at Newark
and Fenton, Del., and at various points near Philadelphia, Pa.
In Pennsylvania it is nowhere abundant yet, although it exists at
Easton, South Bethlehem, and Morrisville, and is reported as far
north as the Pocono Mountains and as far south now as Philadel-
phia. It has also been found near Baltimore, Md., and in Bedford
County, Va.

The range at present, then, includes eight States: Connecticut,
New York, New Jersey, Pennsylvania, Delaware, Maryland, Virginia,
and Massachusetts. Pennsylvania, so far as known, is not infected
to any great extent, except in the eastern border, while Massachu-
setts, Maryland, and Virginia are touched only at one or two points.

CHESTNUT TREE BLIGHT. 9
How THE DISEASE SPREADS.

The yellow fruiting bodies so common on the diseased trees are
constantly giving off millions of summer spores all through the grow-
ing season. These are transported by various agencies to healthy
trees, where they gain entrance through wounds in the bark. Wind
is probably the principal agency, but the spores are no doubt carried
by animals, birds, insects, and by shipment of infected material.

The disease spreads locally through the gradual distribution of the
spores from tree to tree, and at a distance chiefly through the ship-
ment of infected material, such as nursery stock, bark, nuts, and
other products. There is a possibility that long-distance infection is
also effected by means of migratory birds.

There are a number of facts which support the view that the wind
has been the principal agency in spreading the disease over the pres-
ent area. For instance, trees in open spaces exposed to winds, such as
those along roads, at the edges of woods, or near streams or ponds,
are apt to beinfectedsooner than the trees in more sheltered situations ;
trees on slopes or in depressions with diseased trees on higher ground
near them usually become infected, evidently because they have been
exposed to the wind-scattered spores from above; and in thinned
stands, if the disease is present in the neighborhood, almost every
chestnut becomes affected. In this instance the frequency of wounds
is probably a large contributory cause. Dense woods, as a rule, act
as a bar to the progress of the infection, except where the disease is
very prevalent in the vicinity, in which case nothing seems to check
its spread.

AMOUNT OF DAMAGE.

The amount of loss caused by this disease is especially great, because
it has developed in a region where the chestnut trees are extensively
used for ornamental and park purposes. For this reason the losses
have been acutely felt. There is, of course, no satisfactory basis for
estimating the value of trees which are useful chiefly for esthetic
purposes, but the loss is certainly several million dollars.

In Prospect Park, Brooklyn, there are but 6 chestnut trees left
alive out of 1,400. In Forest Park, at Jamaica, Long Island, practi-
cally all the chestnut trees are diseased and many are dead. The
same applies to Bronx Park in New York City. In Nassau County,
in western Long Island, few chestnut tracts have escaped serious dam-
age. In Westchester County, N. Y., it is apparently only a question
of a short time when nearly all the chestnuts will be destroyed. Many
estates have sustained losses in scenic beauty which it is impossible to
estimate. In the part of New Jersey adjacent to New York City the
damage has been of the same character; parks and country estates
have lost large number of fine chestnut trees which would not have
been sold at any price.

Although so far.the injury to ornamental trees has attracted the
most attention, the damage is not confined to these alone. Indeed,
a far more serious phase of the epidemic is the menace to commercial
forest tracts. Already many large tracts in at least five States have
been attacked, and though great damage has been done in certain
localities, it is very small compared with what it will be if the disease
continues to spread.

10 CHESTNUT TREE BLIGHT.

A favorable feature in the situation is that so far the disease has
done most damage in the vicinity of the sea, and there are some indi-
cations that back from the sea, where there is less atmospheric moist-
ure, it may be less virulent and may spread less rapidly. i

The damage which would result from the destruction or extensive
depreciation of the commercial chestnut forests would be many times
that from the loss of ornamental trees. Chestnut is one of the most
rapidly growing and most useful of American forest trees, and it plays
a very important part in the forests of the eastern United States. The
wood is exceedingly durable and has, therefore, been extensively used
for ee poles, and railroad ties, while its grain, color, and ease of
working give it a place among furniture and finishing woods. It is,
moreover, a very vigorous sprouter and lends itself admirably to for-
est management. With the exception of white pine, chestnut proba-
bly makes the most profitable timber crop that can be grown in the
northeastern part of the United States.

UTILIZATION OF DEAD AND DISEASED TREES.

Since the fungus does not work in the wood to any extent and ceases
its activities when the tree is dead, the wood is not damaged as a
result of the disease. In many cases only a part of the tree is affected,
while the rest is healthy and can be utilized without difficulty.

Dead trees are looked upon with suspicion, especially if they are
killed by a disease, and the wood is popularly thought to be weaker
than seasoned live timber. In the case of this fungus there is no
ground for such a prejudice; as a matter of fact, the dead material
is fully as strong as any other timber if it is utilized within a few
years, before the ordinary agencies of decay cause it to deteriorate.

In most of the places where the disease prevails the problem of
cutting and marketing small amounts is a difficult one. The dam-
age from the disease is sudden, and it is often hard to find a market
on short notice, especially for small quantities.

In order to market the material, owners should encourage the con-
tractors and pole buyers, who as a class are also vitally interested
in the perpetuation of the chestnut, to go into sections where the
disease is doing damage. Where the tracts are large enough or sey-
eral are located close together, a portable sawmill might be put in.
Where the quantity of chestnut is small, the best disposal is for ties,
cordwood, and fence posts. Owners of small tracts where the disease
has appeared can often cooperate to great advantage in order to
find a market or make a lumbering operation possible.

MEASURES OF PREVENTION.

The chestnut-bark disease is not like ordinary fungous diseases,
which destroy a tree here and there after a number of years; it is even,
more virulent than the well-known pear blight, which it resembles
in many particulars. It destroys quickly and spreads rapidly, and
it is of the utmost importance to those who are interested in chestnut
forests to secure a means of checking or stamping it out and of pre-
venting its spread to localities which are as yet unaffected.

Seedlings and sprouts are attacked with equal virulence and old
and young trees are killed alike. There is therefore no system of

CHESTNUT TREE BLIGHT. Di

forestry which can be used to control the disease. Two methods of
checking its spread and lessening the source of the infection are
available:

1. To cut out the diseased trees.

2. To institute a quarantine against the shipment of infected
material.

In a forest tract the diseased trees should be cut outright—all
trees which show the least sign of infection should be removed. In
other situations, where the trees have a peculiar value, it may be pos-
sible to save them by cutting off the diseased parts only; but if the
trunk of a tree is attacked, the whole tree, no matter how valuable it
is, Should be cut at once, for it is practically useless to try to save it.

Since the disease generally spreads less rapidly in dense stands than
in thin ones, it will often be possible, by close inspection and the
prompt removal of infected trees, to stamp out the disease altogether
from a forest tract. For the same reason, however, if many diseased
trees are to be removed and their removal would make the stand
very open, it will often be better to make a clean cut of all the chestnut.

All diseased bark should be removed and burned. After that is
done the wood is practically free from infection and can be used or
stored with safety.

Even greater effort should be directed toward preventing the
spread of the disease to localities which are as yet unaffected than
to stamping it out in places where it already has a firm hold.

For this reason definite legislation seems necessary, and it is very
desirable that each State concerned should enact a law providing for
a quarantine against infected chestnut products, chiefly nursery
stock. The law should also provide for systematic and thorough
inspection of the disease and require the cutting out of infected trees
wherever they are a menace to healthy stands of chestnut.

The nature of the disease and the necessity of fighting it should
be made known to the people throughout the region affected by
means of the press and by enlisting the aid of the granges and other
organizations interested.

It is to be hoped that some natural limitation to the destructive-
ness of the disease may be found and that it may be checked by
natural causes. But its rapid spread and its great virulence make
waiting dangerous. Prompt and energetic measures should be
taken to stamp it out wherever it appears.

[Reprint of Bureau of Plant Industry Bulletin No. 141, Pt. V, issued Aug. 30, 1909.]

THE PRESENT STATUS OF THE CHESTNUT BARK DISEASE.

By Haven Mercatr, Pathologist in Charge, and J. FRANKLIN Coins, Special Agent,
Investigations in Forest Pathology.

History oF THE CHESTNUT BARK DISEASE.

In 1904 Mr. H. W. Merkel, of the New York Zoological Park,
observed a disease which was destroying large numbers of chestnut
trees in the city of New York. This disease is what is now known
as the chestnut bark disease. Even at that time it is certain that it
had spread over Nassau County and Greater New York, and had
found lodgment in the adjacent counties of Connecticut and New
Jersey. No earlier observation than this is recorded, but it is evident
that the disease, which would of necessity have made slow advance
at first, must have been in this general locality for a number of years
in order to have gained such a foothold by 1904. Conspicuous as it
is, it is strange that the fungus causing this disease was not observed
or collected by any mycologist until May, 1905, when specimens were
received from New Jersey by Mrs. F. W. Patterson, the Mycologist
of the Bureau of Plant Industry. In the same year Dr. W. A.
Murrill began his studies of the disease, publishing the results in the
summer of 1906. By August, 1907, specimens received by this
bureau showed that the disease had reached at least as far south as
Trenton, N. J., and as.far north as Poughkeepsie, N. Y., and was
spread generally over Westchester and Nassau Counties, N. Y., Bergen
County, N. J., and Fairfield County, Conn.

PRESENT DISTRIBUTION.

The present distribution of the chestnut bark disease is shown on
the accompanying map (fig. 1). By this it will be seen that infec-
tion is now complete in the general vicinity of the city of New York.
Outside of this area the disease already occurs at scattering points
in a number of States. In every case its occurrence has been defi-
nitely authenticated by specimens which have been examined micro-
scopically. Reports have been received indicating that the disease
is found at many other places, but not being substantiated by
specimens these localities have not been shown on the accompanying
map. It is only fair to state, however, that such reports have been
received from points as remote as Cape Cod, Wellesley, and Pitts-
field, Mass.; Rochester and Shelter Island, N. Y., and Akron, Ohio.

The bark disease is entirely different from a disease which during
the past 20 years has caused the death of many chestnut trees on
the Atiantie slope, particularly south of the Potomac River. The
latter disease, which is now being studied by the Department of

12

CHESTNUT TREE BLIGHT. nS

Agriculture, is associated with insects, is much slower in action than
the bark disease, and produces a stag-headed condition of the tree.
It can be quite confidently stated that the bark disease does not yet
occur south of Virginia and at only a few points in that State. ~

Investigations are in progress to determine the origin of the bark
disease in America and the details regarding its spread. The theory
advanced in a previous publication of this bureau,! that the Japanese
chestnuts were the original source of infection, has been strengthened
by many facts. It yet lacks much of demonstration, however, and is
still advanced only tentatively.

While the disease has spread principally from the vicinity of New
York there is much to indicate that it occurred at other points at an
early date. Chester’s Cytospora on a Japanese chestnut, noted at
Newark, Del., in 1902,

may have been the bark oe an : eX

disease. Observations ema
by the junior writer in- ae
dicate that this disease pk
may have been present al

in an orchard in Bedford

County, Va., as early as
1903, and that in Lan-
caster County, Pa., it
probably was present as
early as 1905. Allother
points shown on the
map outside of the area
of general infection ap-
pear to have been in-
fected only within one
or two years.

The bark disease ap-
pears practically to ex-
terminate the trees in
any locality which it in- | Ve
fests. A survey of For- ah

| Fig. 1.—Map of the eastern portion of the United States, showing
est Park, Brooklyn, the distribution of the chestnut bark disease. The heavily

showed ‘‘that 16,695 shaded part shows the counties wherein infection is already
ches tnut trees were Ppelueeiy pegzound sos Shey other points where the disease
killed in the 350 acres of

woodland in this park alone. Of this number about 9,000 were
between 8 and 12 inches in diameter, and the remaining 7,000 or
more were of larger size.”’

In a recent publication Dr. W. A. Murrill estimates the financial
loss from this disease ‘‘in and about New York City” at ‘‘between
five and ten million dollars.” The aggregate loss throughout the
whole area of country affected must be much greater.

The bark disease occurs on both chestnut and chinquapin, regard-
less of age, origin, or condition. It does not occur on any other tree
so far as known. All reports of its occurrence on the chestnut oak
(Quercus prinus) have proved to be unfounded. It is not yet known
whether the poldaclond chinquapin of the Pacific coast (Castanopsis
chrysophylla) is subject to this disease.

1 Bureau of Plant Industry, U. S. Department of Agriculture, Bulletin 121, Pt. VI. 1908,

14 CHESTNUT TREE BLIGHT.

According to Sudworth, the range of the native chestnut is ‘“‘from
southern Maine to northwestern Vermont (Winooski River), southern
Ontario, and southern shores of Lake Ontario to southeastern Mich-
igan; southward to Delaware and southeastern Indiana, and on the
Allegheny Mountains to central Kentucky and Tennessee, central
Alabama, and Mississippi.’”? The range of the chinquapin is “‘from
southern Pennsylvania (Adams, York, Franklin, and Cumberland
counties) to northern Florida and eastern Texas (Neches River).”’
The bark disease may, therefore, be expected to occur at any point
within these limits, as well as in any other localities where the chest-
nut is grown as an ornamental or orchard tree.

CAUSE AND SYMPTOMS.

The disease is caused by the fungus Diaporthe parasitica Murrill
(also known as Valsonectria parasitica (Murriul) Rehm). The spores
of this fungus, brought by some means from a previously diseased
tree, enter the bark through wounds; possibly also in other ways.
The leaves and green twigs are not directly affected. From the

oint of infection the fungus grows in all directions through the inner
park until the growth meets on the opposite side of the trunk or limb,
which in this way is girdled. The wood is but little affected. Limbs
with smooth bark attacked by the fungus soon show dead, discolored,
sunken patches of bark covered more or less thickly with the yellow,
orange, or reddish-brown pustules of the fruiting Langu In damp
weather or in damp situations the spores are extruded in the form of
long irregular ‘‘horns,” or strings, at first greenish to bright yellow
in color, becoming darker with age. Plate XVII, figure 3,shows a part
of a branch of a diseased chestnut tree magnified 34 diameters. In
this illustration the typical appearance of the pustules in damp
weather and the projection of the spores of the fungus in the form
of ‘‘horns,” or threads, are shown. ‘These threads may be especially
conspicuous near the edges of diseased areas. If the spot is on the
trunk or a large limb with very thick bark there is no obvious change
in the appearance of the bark itself, but the pustules of the fungus
show in the cracks of the bark and, on account of the destruction of
the layers beneath, the bark often sounds hollow when tapped. A
patch usually grows fast enough to girdle the branch or trunk that
it is on during the first summer.

The damage may not be immediately apparent, since the water
supply from the roots continues to pass up through the compara-
tively uninjured wood to the leaves, but when in the following spring
the new leaves are put out they are usually stunted and soon wither.
The appearance of such trees-is very characteristic. Plate XVII, fig-
ure 1, shows large chestnut trees killed by the bark disease. In this
illustration the trees to the left show the characteristic stunted foliage,
which indicates that they were girdled during the previous year,
while the tree on the right having no foliage was presumably girdled
by the fungus at least two summers before the photograph reproduced
was taken. Plate XVII, figure 2, shows an orchard tree with recently
girdled branches. Nothing else except an actual mechanical injury—
breaking off of trunk or limb—produces such an effect as is shown in
these illustrations. The imperfectly developed leaves often persist on
the dead branches throughout the summer.

CHESTNUT TREE BLIGHT. as)

The great damage which the disease has done thus becomes most
apparent in the last week of May or the first week in June, giving
rise to the false but common idea that the fungus does its work at
this time of the year, when in reality the harm is done during the
previous summer. If the first attack is on the trunk, of course the
entire tree dies. If, on the other hand, the small branches are first
involved, the tree may live for several years.

It is very easy for a person not familiar with fungi to confuse this
parasite with various other fungi which occur commonly on the dead
wood of chestnut and other trees, such as species belonging to the
genera Calocera, Cytospora, and Cytosporina. The superficial re-
semblance is sometimes very strong, but a microscopical examination
instantly reveals the true nature of the organism in question. On
account of this common confusion no dependable diagnosis of the
bark disease can be made in a new locality without a microscopical
examination of specimens by an expert.

RESTRICTION OF SPREAD.

HOW THE FURTHER SPREAD OF THE BARK DISEASE MAY BE LIMITED.
By THE INSPECTION OF DISEASED NURSERY STOCK.

It becomes more and more evident as this disease is studied that
diseased nursery stock is the most important factor in its spread to
distant points. In that part of the country where it is already well
established in the native chestnuts its progress is rapid and sure, but
there is no evidence at present that it is able to pass to remote dis-
tricts, tens or hundreds of miles away, except on diseased nursery
stock. Of course it is conceivable that the spores are carried by
birds. Such distribution would, however, follow in general the great
lines of bird migration north and south and hence would not be an
important factor in the westérn spread, except locally. During the
summer of 1908 nearly every chestnut nursery and orchard of impor-
tance in the Atlantic States north of North Carolina was visited, and
very few were found free from the bark disease. Several cases were
observed where the disease had obviously spread from the nursery
to adjacent wild trees. This is the only way in which the disease is
likely to spread beyond the Alleghenies.

It is therefore obvious that every State in which the chestnut or
chinquapin grows should as speedily as possible pass a law putting
the chestnut-bark disease on the same footing as other pernicious dis-
eases and insect pests, such as the San Jose scale, against which quar-
antine measures are taken. The Department of Argiculture will be
glad to give detailed suggestions or advice regarding the framing of
such laws. Inspectors who already have legal power to quarantine
against this disease should now take special care that no shipment of
chestnut stock escapes their rigid inspection.

A campaign of education should also be undertaken by patholo-
gists and inspectors in every State in order to acquaint the public
with the nature and appearance of the bark disease, so that it may
be quickly recognized and stamped out in any particular locality in
which it appears. The Department of Agriculture will cooperate in
the following ways: Specimens from suspected trees sent in by any

16 CHESTNUT TREE BLIGHT.

person will be promptly examined and the presence or absence of the
disease reported. Typical specimens showing the disease (with the
fungus previously killed by soaking in formalin to insure against any
infection from this source) will be sent upon application to any inspec-
tor, forester, pathologist, or other State or experiment station officer,
to any nurseryman or orchardist growing chestnuts, or to any botanist
or teacher of botany. So far as the supply permits lantern slides
and photographs will, upon application, hs loaned for special lec-
tures, exhibits, etc., to the officers of States, experiment stations, or
colleges. By these means the inspectors first, and then the general
public, may become familiar with the appearance and work of the
disease in localities that it has not yet reached, and when it does ap-
pear may be able to recognize it before it is too late to take efficient
measures against it.

Although its present distribution is that shown by the map (fig. 1),
the bark disease may be confidently looked for in any orchard or
nursery in the United States that contains chestnut trees. All such
places should therefore be rigidly inspected at the earliest possible
date.

By tHe Prompt DESTRUCTION OF DISEASED TREES.

When the bark disease is first noticed in any locality all the
affected trees should be immediately cut down unless, as in the case
of orchard and some few ornamental trees, they are of sufficient
individual value to warrant special treatment. Diseased trees if
untreated are doomed to death in any case. If permitted to stand,
every such tree becomes a center of infection, certain to spread the
disease to all neighboring trees, and so long as it will soon die if left
to itself the sooner it is cut down the better.

When cut, the brush should be immediately gathered and burned
in order to destroy the fungus in the bark. Whenever the bark is
removed from the trunk—as, for example, when the trees are to be used °
for poles—it should be immediately burned with the brush. Even
when the tree is to be used for firewood an effort should be made to
cut off at least all the diseased patches of bark on the trunk and
large limbs when the tree is cut and to burn this bark along with the.
brush; otherwise the brush and the piled wood will continue to
spread infection, since it has been found that the fungus continues
alive on dead bark for at least six months after cutting.

Sprouts arising from the stumps of cut trees will be free from the
disease for the first year at least, but must then be carefully inspected
to be sure that no infection has persisted.

By THE TREATMENT OF DISEASED TREES.

During the past two years the Office of Investigations in Forest
Pathology has been conducting certain experiments and collecting
information in regard to the best methods of treating diseased trees.

At present it is impossible definitely to record general beneficial
results from any of the sprayings which have been undertaken or have
been under observation. This may in part be due to the fact that it is
yet too early to judge satisfactorily all the results and in part, per-
haps, to the infrequency of sprayings.

CHESTNUT TREE BLIGHT. 1

Observations and experiments seem to bear out the statement that
it is very improbable thie any method of spraying can interfere with
the growth of the fungus if it has once established itself in the inner
bark, but it may be of considerable importance in preventing the
development of spores which come from other trees or from other
parts of the same tree.

It has already been demonstrated that the crotches of branches
and enlarged bases of sprouts are very susceptible to infection because
they are favorable places for the lodgment of water, dust, spores, etc.
In a large majority of cases infections are definitely known to ha*e
originated at a point where the outer bark had been injured in some
way, leaving the inner living bark exposed, or where the entire bark
over a more or less limited area had been stripped from the tree or
eracked and split away from the wood. Certain injuries which are
known to have afforded entrance for the disease have been of such a
nature that they might easily be overlooked, while others have been
quite obvious, even to the careless observer. Among the latter may
be mentioned broken limbs, split hmbs, branches which have been
carefully cut but not properly treated with tar or paint, bruises from
hames, plows, and cultivators; also poor grafts and diseased grafting
scions. Among the former may be included bruises from boot heels,
climbing spurs, holes made by borers and other insects, knife and
saw cuts, and frost cracks.

Almost the only treatment that can at present be safely recom-
mended as surely retarding the spread of the disease to a greater or
less extent is one which will never be of practical use except in the
case of orchard trees or certain valuable ornamental trees. It consists
essentially in cutting out the infected branches or areas of bark and
carefully protecting the cut surfaces from outside infection by means
of a coat of paint or tar. This cutting must be thoroughly done and
the bark of every infected place entirely removed for a distance of at
least an inch (where the size of the branch permits) beyond the
characteristic, often fan-shaped, discolored areas produced by the
erowing fungus in the inner bark. All small infected twigs or
branches should be cut from the tree, the cut being made well back
of the diseased area. A pruning knife with an incurved tip, a hollow
gouge, or any other clean-cutting instrument will serve for cutting
out diseased spots.” So far as the exigencies of the case will permit,
all borers’ holes should be cut out. It has been repeatedly observed
in the field that infection often starts where borers are at work, or
even at the old holes made by them. The paint or tar may be applied
by means of a good-sized brush, care being taken to cover every part
of the cutting. Treatment should begin, or observations at least, at
the base of the tree and the fact ascertained whether the disease has
already girdled the trunk. If such is the case it will be a waste of
time to attempt any treatment; instead, cut the tree down at once.
A rigid watch must be kept, especially during the growing season, for
new infections or infections which were overlooked in the earlier
examinations, and if any are observed they must be treated promptly
as above mentioned. Constant vigilance is necessary to keep the
disease in check. It is suggested that examinations be made about
June 1, July 15, and September 1. During a very rainy or foggy
season, when conditions are particularly favorable for the growth of
fungi, it may be advisable to inspect as often as once a month.

43017°—S. Doc. 653, 62-2 2

18 CHESTNUT TREE BLIGHT.

In regions in which the disease is so widespread that almost every
tree is infected, as, for instance, within 25 miles of the city of New.
York, it is extremely doubtful whether any individual treatment will
pay. Under such conditions immediate reinfection is almost sure to
occur at one or more of the small unnoticed abrasions or injuries
which are quite certain to exist on most trees. In a region, however,
where only isolated cases have yet appeared it is quite possible to
stamp out the disease, or at least to prevent its rapid spread, by
promptly cutting out and carefully burning all diseased bark and
limbs, thus destroying these new sources of infection. If a tree is
too badly infected to be worth treating it should not be left standing,
for it will then become a continual menace to all surrounding chest-
nuts.

The Office of Investigations in Forest Pathology asks the cooper-
ation of all persons who have observed the disease or experimented
with it in any way. If such people will send in an early report of the
kind of treatment used, time of treatment, methods employed, and
results obtained (even if adverse), it may be possible to arrive at an
earlier and more definite conclusion in fae to the possibilities or
impossibilities of control than would otherwise be the case.

CONCLUSIONS.

It is to be hoped that in the economy of nature some limiting fac-
tor will arise to check the spread of the bark disease before it has
wrought the same destruction throughout the country that it already
has in the vicinity of New York. But at present there is nothing in
sight that promises even remotely to check its spread into new terri-
tory except the general adoption of the measures advocated in these
pages. It can not be argued that because of its apparently recent ori-
gin and rapid spread it will soon disappear of itself. Such diseases as
pear blight and peach yellows have been in the country for more than
a century and yet show no sign of abating except when actively
combated by modern quarantine methods. Nor can any conclusions
be drawn from the fact that chestnuts in the Southern States have
suffered from a disease during the past twenty years, since, as already
stated, that is a totally different thing from the bark disease.

Where the bark disease is already firmly established and has
attacked 50 per cent or more of the chestnut trees, as in the vicinity
of the city of New York, it is probably too late to try to do anything,
but where the disease is just appearing there is no reason to doubt that
strict quarantine methods aula as well to this as to any other
disease, whether of plants or animals. The question to settle is sim-
ply which is more costly—to use the methods recommended or to
ees the trees. The people concerned must decide.

[Reprint of Farmers’ Bulletin No. 467, issued Oct. 28, 1911.]

THE CONTROL OF THE CHESTNUT BARK DISEASE.

By Haven Mertcatr and J. FRANKLIN COLLINS.

THE DISEASE.
HISTORY AND DISTRIBUTION.

The chestnut bark disease was first recognized as a serious disease
in the vicinity of New York City in 1904, and the first” publication
regarding it appeared in 1906. ‘There is reliable evidence, however,
that it was present on Long Island at least as early as 1893. Its
origin is unknown, but there is some evidence that it was imported
from the Orient with the Je apanese chestnut. » This view is not, how-
ever, held by all investigators. But whatever may have been its time
or place of origin, it is certain that it has now spread into at least
10 States, as is shown by the accompanying map (fig. 2). In the
vicinity of New York City and through adjacent counties it has
lulled practically all chestnut tr Bese "Throughout a much larger

neighboring area, as shown in figure 2, practically all chestnut trees
are infected. Outside of this area, throughout the country from the
northern border of Massachusetts and from Saratoga County, N. Y.,
to the western border of Pennsylvania and the southern border of
Virginia, scattering areas of infection are known to occur and may
be expected at any point.

So far as is now known, the bark disease is limited to the true
chestnuts—that is, to the members of the genus Castanea. The
American chestnut, the chinquapin, and the cultivated varieties of
the European chestnut are all readily subject to the disease. Only
the Japanese and perhaps other east Asian varieties appear to have
resistance. Inspite of popular reports to the contrary, 1t can be quite
positively stated that the bark disease is not now known to occur on
living oaks, horse-chestnuts, beeches, hickories, or the golden-leaf
chinquapin (Castanopsis chrysophylla) of the Pacific coast.

FINANCIAL LOSSES.

The bark disease appears ultimately to exterminate the chestnut
trees in any locality which it infests. A survey of Forest Park
(Brooklyn) showed ‘‘that 16,695 chestnut trees were killed in the
350 acres of woodland in this park alone. Of this number, about
9,000 were between 8 and 12 inches in diameter, and the remaining
ve ,000 or more were of larger size.”’ Three years ago the financial loss
from this disease ‘‘in and about New York City” was estimated at
‘*between five and ten million dollars.”

19

20 CHESTNUT TREE BLIGHT.

The writers regard $25,000,000 as a conservative estimate of the
financial loss from this disease up to 1911. In many localities the
greatest damage has been among chestnuts grown for ornamental
purposes, which have a value greatly in excess of their value as lumber.

epression in the value of real estate, especially suburban or near-
suburban, owing to the death of the chestnut trees, must be taken
into account in an estimate of this kind, as well as the loss of the
trees themselves.

Fig. 2.—Map of the northeastern part-of the United States, showing the distribution of the chestnut bark
disease. The horizontally lined part shows the approximate area wherein the majority of chestnut trees
are already dead from the bark disease. The part marked by vertical lines shows the approximate area
wherein infection is already complete. The round dots show the location of advance infections of the
disease. Many of these have already been eradicated. The map has been compiled from both observa-
tions and correspondence. The writers are under especial obligations to Dr. Perley Spaulding, Prof. A.
H. Graves, Mr, I. C. Williams, Mr. W. H. Rankin, Mr. J. F. O’Byrne, Mr. F. W. Besley, Dr. Ernest S.
Reynolds. and Mr. H. G. MacMillan, for data along this line. According to Dr. G. P. Clinton (Connect-
icut Agricultural Experiment Station, Report of the Botanist, 1909 and 1910) there are many more
points of infection in Connecticut than are shown on this map. ;

CAUSE AND SYMPTOMS.

The chestnut bark disease is caused by a fungus parasite known
under the technical name of Diaporthe parasitica Murrill. When
any of the microscopic spores (reproductive cells) of thts fungus gain
entrance into any part of the trunk or limbs of a chestnut tree they
give rise to a spreading ‘‘sore’”’ or lesion, which soon girdles the tree.
If the part attacked happens to be the trunk, the whole tree in con-
sequence is killed, perhaps in a single season. If the smaller branches
are attacked, only those branches are killed, or only those portions of

CHESTNUT TREE BLIGHT. 21

branches beyond the point of attack, and the remainder of the tree
may survive for several years (fig. 3).

Some of the symptoms are quite prominent. Limbs with smooth
bark attacked by the fungus soon show dead, somewhat discolored,
sunken areas (occasionally with a raised margin), which continue to
enlarge and soon become covered more or less thickly with yellow,
orange, or reddish-brown spots about the size of a pinhead. These
spots are the pustules of the fruiting fungus. In damp weather or
in damp situations, masses of summer spores are extruded in the
form of long, irregularly twisted strings or “‘horns,’’ which are at first
bright yellow to greenish yellow or even buff, becoming darker with age
(Pl. XVII, fig.3). If the lesion is on the trunk or a large limb with
very thick bark, there is no obvious change in the appearance of the
bark itself, but the pustules show in the cracks and the bark often
sounds hollow when tapped. After smooth-barked limbs or trunks
are girdled the fungus continues to grow extensively through the
bark, sometimes covering the entire surface with reddish-brown

Fic. 3.—Large chestnut tree partly killed by the bark disease. Note the sprouts with leaves near the top,
the dwarfed leaves on the lower right-hand limb, and the healthy lower branches with leaves.

pustules (fig. 4). These pustules produce mostly winter spores
(ascospores), although occasionally the long strings of summer spores
(Pl. XVII, fig. 3) are also produced, even on bark that has been
dead at least a year.

After a branch or trunk is girdled, the leaves change color and
sooner or later wither. Such branches have a very characteristic
appearance and can hardly be mistaken for anything else, except in
certain localities where the work of twig-girdling insects may pro-
duce a similar appearance in the spring. In case the girdling by
the fungus is completed late in the season, the leaves of the follow-
ing spring assume a yellowish or pale appearance and do not develop
to their full size (fig. 3). If the girdling is completed between spring
and midsummer the leaves may attain their full size and then turn
a somewhat characteristic reddish-brown color, which can easily be
detected at a long distance. Later this leaf coloration changes to
a more brownish tinge and the leaves are commonly persistent for a
considerable time. The chestnut fruits (burs) on a spring-girdled

De CHESTNUT TREE BLIGHT.

branch may or may not attain full size, according to whether the
girdling by the disease was completed late or early in the spring.
These burs commonly persist on the tree during the following win-
ter, thus producing the only symptom which is at all conspicuous
during the leafless season. The great damage which the disease has
done in the late summer thus becomes most evident at the beginning
of the next season, and that done in the spring becomes evident later
in the same season, giving rise to the false but common idea that
the fungus does its work at the time of year that the leaves change
color, when in reality the harm was done much earlier.

Fia. 4.—Dead chestnut bark showing pustules of the parasitic fungus bearing winter spores.

Perhaps the most easily seen as well as the longest persistent
symptom of the bark disease is the prompt development of sprouts,
or “suckers,” on the trunk of the tree (fig. 3) and at its base, or
somewhat less frequently on the smaller branches. Sprouts may
appear below every girdling lesion on a tree, and there are usually
many such lesions. These sprouts are usually very luxuriant and
quick growing, but rarely survive the second or third year, as they
in turn are killed by the fungus. The age of the oldest living sprout,
as determined by the number of its annual rings, is an indication of
the minimum age of that portion of the infection immediately above

CHESTNUT TREE BLIGHT. oa

it. Sprouts are sometimes produced as a result of other injuries;
for instance, trees girdled by borers may develop sprouts, but these
are generally less rapid in growth and are distributed with greater
uniformity over the trunk.

MEANS OF SPREAD AND ENTRANCE.

The disease is spread by the spores of the fungus, of which there
are two kinds. As both kinds of spores appear to be sticky, there
is no evidence that they are transmitted by wind except where they
may be washed down into the dust and so blown about with the
dust. The spores are spread easily through short distances by rain;

articularly they are washed down from twig infections to the
fer parts of the tree. There is strong evidence that the spores
are spread extensively by birds, especially woodpeckers, and there
is also excellent evidence that they are spread by insects and by
various rodents, such as squirrels. The disease is carried bodily for
considerable distances in tan bark and unbarked timber derived from
diseased trees. One of the most prolific sources of general infection
has been the transportation of diseased chestnut nursery stock from
infected to uninfected localities.

When the spores have once been carried to a healthy tree, they
may develop in any sort of hole in the bark which is reasonably moist.
These may be wounds or mechanical injuries, but by far the most
common place of infection is a tunnel made by a borer. Borers’
tunnels are moist, even in dry weather, and in them the spore finds
surroundings favorable to its development. In many parts of the
country where the disease is prevalent there is very direct evidence
that bark borers, and particularly the two-lined chestnut borer
(Agrilus bilineatus), are directly associated in this way with 90
per cent or more of all cases of this disease. We are informed that
the Bureau of Entomology will issue a circular on the insects asso-
ciated with the chestnut bark disease.

The writers have no definite evidence, experimental or other-
wise, to show that a tree with reduced vitality is more susceptible
to infection, or that the disease spreads more rapidly in such a
tree, than in a perfectly healthy and well-nourished tree of either
seedling or coppice growth, provided that such reduced vitalit
does not result in or is not accompanied by bark injuries tinetiels
which spores can gain entrance.

THE CONTROL OF THE DISEASE.
ELIMINATION AND QUARANTINE.
FUNDAMENTAL OBSERVATIONS AND EXPERIMENTS.

No method of immunizing individual trees against the bark dis-
ease is yet known, and no method of treating or curing them when
once attacked is certain in its results. While this is unfortunate
from the standpoint of the owner of orchard trees and large orna-
mental trees of great individual value, no method of dealing with
single trees—surgery, medication, spraying, ete.—however successful
in itself, would meet the demands of the present situation. It is not

94 CHESTNUT TREE BLIGHT.

practicable at present to apply any individual method of treatment
to forest trees; the individual tree is not worth it, and will not be
for many years. Therefore, so far as the chestnut forests are con-
cerned, we do not need to regret particularly that no individual
treatment has yet been discovered that is entirely effective. |
Fortunately, however, there is a method of dealing with the situa-
tion which is applicable to the country as a whole and which, so
far as tested, is practicable. Early in the course of the writers’
investigations it became evident that the disease advances but slowly
in a solid line, but instead spreads from isolated centers of infec-
tion, often many miles in advance of the main line of disease. That
such is the case is evident from a glance at figure 2. It therefore
seemed probable that if these advance infections could be located
at a reasonably early stage they could be eliminated at relatively
little expense, thus preventing further spread from these points at
least. Accordingly, the country within approximately 35 miles
of Washington, D. C., was chosen in the fall. of 1908 as preliminary
territory in which to test this method of control. This section has
since been gone over fairly thoroughly once a year. As will be seen
by figure 2, 14 points of infection were located, and the infected
trees destroyed. Most of this work was done by the senior writer.
The largest infection was a group of nursery trees that had been
imported from New Jersey; the smallest, a single lesion on a small
branch of a large forest tree. In one case 11 forest trees in a group
were infected, the original infection having been two trees, dating
apparently from as early as 1907. Up to the present time (June,
1911) the disease has not reappeared at any point where eliminated
and the country within a radius of approximately 35 miles from
Washington is apparently free from the bark disease, although new
infections must be looked for as long as the disease remains elsewhere
unchecked. It is therefore believed that this method of attack will
pe equally practicable in other localities, and if carried out on a
arge scale will result ultimately in the control of the bark disease.

LEGAL CONSIDERATIONS.

In carrying such a scheme of control into effect on a large scale,
however, legal difficulties are at once encountered. The bark dis-
ease threatens the extinction of the chestnut throughout its range.
As it has already been found in at least 10 States and the District of
Columbia, it is essentially a national issue, but there is no law
whereby the Federal Government can attempt to cope with the
emergency. Each State must act on its own initiative and control
the disease or let it go as its officers and legislative bodies see fit.
Herein lies one of the most serious aspects of the matter; for if one
State elects to undertake control of the disease it will be seriously
handicapped if neighboring States do not. Any method of elimina-
tion, isolation, or quarantine in dealing with any disease of plants,
domestic animals, or human beings necessitates general cooperation.
It is not practicable to try to control the bark disease solely by the
cooperation of individual owners of chestnut woodland, since a sin-
gle indifferent or obstinate person can nullify the efforts of an entire
community. The control of the chestnut bark disease must theré-
fore be undertaken by the separate States under special legislation.

OHESTNUT TREE BLIGHT. 25

Possibly in certain States the crop and woodland pest laws, which
ordinarily apply only to nursery stock, may be broad enough to
include this sees but in most States the first thing to be done
is to obtain the necessary legal authority and an appropriation for
action along the following lines, as has already been done in Penn-
sylvania.

Tar Meruop IN Deratn.

Locating advance infections (‘‘scouting”’).—The first thing to
be done in each State is to determine the exact range of the disease
in that State, and particularly to locate the advance points of infec-
tion. This is by he the most difficult feature of the entire pro-
gram, because the work must be directed and in large measure car-
ried out by experts; otherwise diseased trees will be left, and the re-
sults can not be depended upon. It is best intrusted to professional
plant pathologists, or at least to botanists familiar with fungi and
the iliseline of fungi, and even these must have some preliminary
knowledge of this particular disease. The symptoms of the disease
are too obscure and the means of locating it too intricate to make it
possible for a person without a professional knowledge of plant dis-
eases to deal successfully with the situation, no matter how well in-
formed in agriculture or forestry or how experienced in the care of
trees. It is suggested that in most States this part of the work
would be best handled by the pathologists of the State agricultural
experiment stations.

For assistants the pathologists having this work in charge should
choose the best scientific observers obtainable, regardless of other con-
siderations, but persons with some knowledge of plant pathology are
to be preferred. College students trained in these lines are usually
available, for the summer vacation at least, and make in many
respects the most desirable ‘‘scouts” for this work. But all ‘‘scouts”’
must be carefully and individually trained by the expert in charge.

Attention should first be directed to the advance spots of infection
already known to exist, and when found the diseased trees should be
destroyed or marked for destruction. No difficulty will be experi-
enced in locating infections 2 years old or more, but the greatest diffi-
culty will be met in locating infections of the current year. Ever
tree in the immediate vicinity of older infected trees must be carefully
gone over. Many dubious cases will be found, and from such trees
samples of the suspected bark must be taken and sent to some labora-
tory for expert judgment. It is absolutely necessary to have arrange-
ments with some laboratory whereby ae work can be done and the
results promptly reported.

After the spots already known to exist have been delimited and
the trees destroyed or marked for destruction, the search should be
continued. It is best next to clearly define the location of the main
line of advance of the disease, back of which infection is general.
Working away from this line as a base, a complete survey of the
remainder of the State must be made, until it is reasonably certain
that all spots have been located.

Scouting is best discontinued as soon as the leaves change color in
the fall, since from October to April, inclusive, the symptoms are
very obscure. Practically no sign of the disease is visible from a dis-
tance, except in those cases where the burs persist on the older trees.

26 CHESTNUT TREE BLIGHT.

Even the pustules of the fungus become weathered, so that even a
close examination of a tree may not yield visible results. But the
destruction of trees already marked can continue through the winter.

Destroying advance infections—Many of the advance infections
will be found to consist of single trees or of less than half a dozen
trees. These may perhaps be destroyed by the person who finds them,
especially if remote from other infections; but the greater part of
the work of elimination is best handled by other persons under sepa-
rate direction. Undoubtedly this work can be best directed in each
State by the State forestry officials.

The work of elimination should be done as soon as possible after
the diseased trees are located, but may be done at whatever time of
year is most convenient, since new infections will be detected by the
scouting of the following year. The marked trees should be cut
down. So far as is now known, the timber may be safely utilized in
various ways, provided it is barked. The bark and brush should be
piled over the stumps and, as soon as practicable, burned. If it is
not practicable to have the fire over the stumps, the stumps should
be barked to the ground; but in any case the bark and brush must
be burned.

It will be readily seen that the task of locating the disease, and the
subsequent one of eliminating it, call for very different talents. The
“scouting” calls for carefully trained and absolutely accurate scien-
tific observers working under the most highly specialized direction
that can be obtained. The work of elimination calls not for scien-
tific knowledge, but for executive ability, tact in dealing with
owners and in otherwise administering the law, and a knowledge of
forestry and of lumbering, market, and transportation conditions.
In a word, the first is a task for pathologists, the second for foresters.
Another advantage of thus dividing the work is that a certain rivalry
will usually develop, resulting in more thorough work on both sides.
It is, moreover, of the utmost importance to have as many different
forces and interests as possible in any given State working toward
the common end of controlling this disease.

tstablishing the “immune zone.”’—After all advance spots of
infection are eliminated, attention must be turned to the main line
of advance—the edge of the area of general infection. Here the
problem will present local differences. It may prove necessary in
some States to destroy all chestnut trees, diseased or healthy, in a
belt 10 to 20 miles wide, or possibly less. Advantage must be taken
of natural barriers to infection, such as unforested areas or wooded
areas without chestnuts. In this way an ‘immune zone” will be
established, across which the disease can not easily be transmitted by
merely local agents. Back of this line the chestnut trees may be
abandoned to the disease. Every effort should be made, however, to
have them cut down and the timber utilized as soon as possible,
since they remain sources of distant infection as long as any spore-
laden bark or diseased sprouts remain on them.

Quarantine-—Whether any restrictions are placed upon the move-
ment of chestnut products from the area of complete infection to the
protected territory will depend largely on local conditions and must
be left to the judgment of State authorities. Barked timber can
probably be moved with comparative safety. It will always be
desirable to limit the movement of unbarked chestnut timber and fire-

CHESTNUT TREE BLIGHT. Paull

wood and of chestnut tan bark. An inspection of local conditions
will readily determine whether the danger from these sources is
sufficiently great to warrant the business inconvenience which would
be caused by the quarantine of any or all chestnut products.

Program for the second year.—The work for the second year will
consist mostly of reinspection of the advance spots where the bark
disease has been eradicated the previous year and of general scouting
to locate new spots. If the work of the first year has been thoroughly
done and there has been time to complete the elimination of all spots
located, only scattering infections may be expected. From this time
on the persons in charge of scouting will have the bulk of work and
responsibility.

THE EXAMPLE OF PENNSYLVANIA.

Pennsylvania enjoys the distinction of being the first and so far the
only State to undertake in any way the control of the chestnut-bark
disease. In the summer of 1910 the Main Line Citizens’ Associa-
tion—an organization of citizens residing along the main line of the
Pennsylvania Railroad near Philadelphia—appointed a committee of
seven, under the chairmanship of Mr. Harold Peirce, to determine the
status of the disease in that locality and to see what could be done
toward controlling it. An extensive local survey of the disease was
made under the direction of Mr. I. C. Williams, deputy State forest
commissioner. ‘The committee soon became convinced that the prob-
lem was of State and even national importance, and could ae be
solved by legislation and by the broadest cooperation. Accordingly
they devoted their energies to securing the passage by the Pennsyl-
vania Legislature of the following bill, which has now become a law.
This law is almost unique in conservational legislation, and on ac-
count of its important bearing as precedent for similar laws in other
States it is here reproduced in full.

AN ACT To provide efficient and practical means for the prevention, control, and eradication of a disease
affecting chestnut trees, commonly called the chestnut-tree blight; providing for the destruction of trees
so affected; creating a commission to carry out the purpose of this act; fixing penalties for violation of
the provisions hereof; and making an appropriation therefor.

Section 1. Be it enacted by the Senate and House of Representatives of the Common-
wealth of Pennsylvania in General Assembly met; and it is hereby enacted by the authority
of tie same: That a commission to consist of five members, to be appointed by the
governor for a period of three years from the date of the approval of this act, and to be
called ‘‘The Commission for the Investigation and Control of the Chestnut-Tree
Blight Disease in Pennsylvania,’’ is hereby created, with power to ascertain, deter-
mine upon, and adopt the most efficient and practical means for the prevention, con-
trol, and eradication of a disease of the chesinut tree commonly known as the chestnut-
tree blight disease; and for this purpose, in collaboration with the department of
forestry, or. otherwise, to conduct scientific investigations into the nature and causes
of such disease and the means of preventing its introduction, continuance, and spread;
to establish, regulate, maintain, and enforce quarantine against the introduction and
spread of such disease; and, from time to time, to adopt and prescribe such regulations
and methods of procedure as to it may seem necessary and proper for carrying into effect
the purpose of this act, and exercising the powers and authority hereby conferred:
Provided, That in the work of collaboration by the commission with the department
of forestry said department may employ such means, and make detail of such men,
and do such other things, as may seem to be necessary or expedient to accomplish the
purpose of this act.

Sec. 2. Any member of the commission, or any of its duly authorized agents or
employees, shall have the right, at any time, to enter upon any premises, wild lands,
farms, fields, private grounds, and inclosures for the purpose of examining into the
condition of any chestnut tree or trees thereon, and determining whether or not such

98 CHESTNUT TREE BLIGHT.

trees, or any of them, have been attacked or infected by the chestnut-tree blight;
and whenever this disease is found to exist, such commissioners, their duly authorized
agents and-employees, shall, in all practicable ways, cooperate with the owners of
such trees in and for the removal, cure, control, and eradication of such disease, and:
the prevention of its spread to other chestnut trees upon adjoining and other properties;
shall specifically advise and. direct such owner how he shall proceed for the accom-
plishment 6f these ends; and shall leave with such owner, his agent, tenant, or other
representative having charge of such trees, a notice, in writing, containing a descrip-
tion or plan specifically designating the trees so found to be diseased, and full and
specific instructions for the treatment of such trees, or for the removal and destruction
of designated parts thereof, or of an entire tree or trees, as the case May require.

Src. 3. If any owner of such trees, so found to be diseased by the said commission,
its duly authorized agents or employees, shall neglect or refuse to cooperate in applying
the necessary remedies for the removal, cure, control, and eradication of such disease,
and the prevention of its spread to other chestnut trees upon adjoining and other
properties; or shall neglect or refuse to coniply with the requirements of the notice
aforesaid, prescribing the treatment which shall be applied to such trees, so found to
be diseased, within 20 days from the time such notice shall have been served, the said
commission may at once proceed, through its duly authorized agents and employees,
to do whatever may be found by it to be necessary and proper to accomplish the cure,
control, or eradication of such disease and the prevention of its spread to other chestnut
trees; and for this purpose, whenever it may be found necessary may remove, cut
down, and destroy, or cause to be removed, cut down, or destroyed, any trees or parts
of trees so found to be infected with such disease; and shall immediately thereaiter
duly certify to the owner of such trees, so treated or destroyed, or to his tenant, agent,
or other representative in charge of such trees, the amount of the cost or expenses
actually incurred by the commission in the treatment, removal, or destruction of such
trees; and if the amount of such expense, so certified, shall not be paid by such owner
of said trees, so treated, removed, or destroyed, within 60 days after it shall have been .
so certified, the same may be recovered by the said commission, from such owner,
‘by an action in the name of the Commonwealth, in the same manner as debts of like
amount are now recoverable, and when recovered may be used by said commission
in carrying out the purposes of this act. ;

Provided, however, That any owner or owners of trees, his or their tenants, agents,
or representatives, who may be dissatisfied with any decision, order, or notice of any
member of the commission, or any of its agents or employees, directing or prescribing
the treatment, removal, or destruction of trees belonging to or controlled by them,
shall have the right within 10 days from the time of the service upon them of such
order or notice to appeal therefrom, in writing, to the commission, which shall there-
upon, without avoidable delay, direct a reexamination of the premises or trees in
question, by competent experts, who shall make report of their findings to the com-
mission; which shall then fix a time and a place for a hearing before it, upon such
appeal, and notify the person making appeal thereof. All further proceedings under
such order or notice shall be suspended until the decision of the commission shall have
been formally rendered.

Sree. 4. Whenever, in the judgment of the commission, it may be necessary to destroy
chestnut trees not affected by the chestnut-tree blight, for the purpose of establishing
a quarantine to prevent and control the spread of the disease, the owner of such trees
shall be reimbursed for the loss of all the good and unaffected trees so destroyed; the
amount to be paid therefor to be not greater than the stumpage prices of such trees,
prevailing at the time in the locality where such trees grew; such value to be deter-
mined by the commission, by such method or procedure as it may adopt, and payment
therefor to be made from the fund hereinafter specifically appropriated for the use of
the said commission in performing the duties required by this act. Should any owner
of trees be dissatisfied with the amount awarded to pay for the destruction of such good
and unaffected trees, said owner shall have all the remedies now existing, or which
may hereafter be provided by law, for the protection of his interests.

Src. 5. Any person who shall willfully violate any of the provisions of this act, or
any of the regulations of the commission intended to assist in carrying this act into
effect; or shall willfully resist or interfere with any agent or employee of the said com-
mission in the performance of his duties in accordance with the regulations and orders
of the commission, under the provisions hereof, shall be deemed guilty of misdemeanor,
and shall upon conviction thereof be punished by a fine not exceeding $100, or by
imprisonment not exceeding one month, either or both, at the discretion of the court.
The word ‘‘person,”’ as used in this act, shall include not only individuals or natural
persons, but as well artificial persons, existing only in contemplation of Jaw, and shall
be construed to mean partnerships, limited partnerships, joint-stock companies, and
corporations, and the officers, agents, and employees of the same.

CHESTNUT TREE BLIGHT. 29

Sec. 6. The members of the commission shall serve without pay, but shall be reim-
bursed for all actual expense incurred by them in exercising the powers conferred
upon them and performing the duties required by this act. The employees of the
commission shall receive such compensation for their services as the commission shall
determine will fairly compensate them for the work to be done. The commission
shall be furnished with suitable rooms in the Capitol building at Harrisburg, or else-
where, by the Superintendent of Public Grounds and Buildings. The sum of $25,000
is hereby specifically appropriated, to be immediately available upon the approval
of this act, for the payment of such expense as may be incurred by the commission, for
such scientific research and for office expenses, as in their judgment may be necessary
to comply with the provisions hereof, said appropriation to be available until the Ist
day of June, A. D. 1913; and the further sum of $250,000, or so much thereof as shall
be necessary, is hereby specifically appropriated, to be available only upon the
approval of the governor, for the performance of all other duties herein required to
be done; as, for quarantine, removal of diseased trees or other trees, conducting out-
side investigations and operations, and every other means of eradication and control,
as to it may seem necessary in complying with the provisions hereof.

‘Src. 7. All acts or parts of acts inconsistent herewith are hereby repealed.

The commission authorized by the bill has been appointed by the
governor of Pennsylvania and consists of the fallamane persons:
Mr. Winthrop Sargent, chairman; Mr. Harold Peirce, secretary;
Messrs. Samuel T. Bodine, George F. Craig, and Theodore N. Ely.
Persons desiring information regarding the work on this disease in
Pennsylvania should address the executive officer of the commission,
Mr. Samuel B. Detweiler, 1112 Morris Building, Philadelphia, Pa.

INSPECTION OF DISEASED NURSERY STOCK.

As has been indicated, diseased chestnut nursery stock has in the
past been a most important factor in the spread of the bark disease.
On account of a well-grounded fear of this disease much less nursery
stock is being moved now than formerly, but there is still enough to
constitute a serious source of danger. It is therefore obvious that
every State in which the chestnut grows, either naturally or under
cultivation, should as speedily as possible pass a law putting the
chestnut bark disease on the same footing as other pernicious diseases
and insect pests, such as peach yellows and the San Jose scale, against
which quarantine measures are taken. Many inspectors already have
legal power to quarantine against the bark disease on chestnut nurs-
ery stock, and they should now take special care that no shipment,
however small, escapes their rigid inspection.

The most serious practical difficulty in inspecting nursery stock for
this as for other fungous diseases lies in the fact that practically all
State inspectors are necessarily entomologists, and are not trained in
recognizing the more obscure symptoms of fungous diseases. Nursery
trees affected by the bark disease rarely show it prominently at the
time when shipped; the threads of summer spores or the yellow or
orange pustules are rarely present, and usually all the inspector can
find is a small, slightly depressed, dark-colored area of dead bark,
usually near the ground, hol is easily overlooked or mistaken for
some insignificant injury. Upon cutting into such a spot, the inner
bark shows a most characteristic disorganized “punky” appearance,

uite different from that of any other bark injury; but it is impos-
sible to adequately describe this appearance without recourse to
colored illustrations. Occasionally a yellowish-brown band, either
girdling or partly girdling the young tree, may be seen; this is very
characteristic, but is so prominent a symptom that it may be noticed
at the nursery, and presumably trees so affected will not be shipped.

30 CHESTNUT TREE BLIGHT.

If infected trees are set out they develop the disease with its char-
acteristic symptoms the following spring. But on account of their
small size such trees are girdled and die before the end of the sum-
mer, often in two or three weeks. Meanwhile they are spreading
the disease to neighboring orchard and forest trees. Orchardists
and nurserymen purchasing chestnut trees are therefore warned to
watch them closely during the first season, no matter how rigidly
they may have been inspected.

INDIVIDUAL TREATMENT OF DISEASED TREES.

Where valuable ornamental, shade, or orchard chestnut trees be-
come infected in one or more spots, the life and usefulness of such
trees can be prolonged for several or for many years, depending
largely upon the thoroughness with which the recommendations
herein given for cutting out the diseased areas (lesions) are carried
out. These recommendations are based upon the results of extensive
experiments with hundreds of lesions during the past four years.
These experiments were performed for the most part by the Junior
writer.

The essentials for the work are a gouge, a mallet, a pruning knife,
a pot of coal tar, and a paint brush. In the case a a tall tree a
ladder or rope, or both, may be necessary, but under no circum-
stances should tree climbers be used, as they cause wounds which
are very favorable places for infection. Sometimes an ax, a saw,
and a long-handled tree pruner are convenient auxiliary instruments,
though practically all the cutting recommended can be done with a
gouge with a cutting edge of 1 or 13 inches. All cutting instruments
should be kept very sharp, so that a clean and smooth cut may be
made at all times.

By cutting with the gouge into a diseased area a characteristically
discolored and mottled middle and inner bark is revealed. All of
this diseased bark should be carefully cut out for at least an inch
beyond the discolored area if the size of the branch will allow it.
This bark should be collected in a bag or basket and burned. _ If the
cutting is likely to result in the removal of the bark for much more
than half the circumference of the branch or trunk, it will probably
be better to cut off the entire imb or to cut down the tree, as the
case may be, unless there is some special reason for attempting to
save the limb or tree. The fungus usually, though not always, de-
velops most vigorously in the inner bark next to the wood. When
this is the case, not only all the diseased bark and an inch of healthy
bark around it must be removed, but at least two or three annual
layers of wood beneath the diseased bark must also be gouged out.
Special care should be taken to avoid loosening the healthy bark at
the edges of the cut-out areas. Except in the early spring this is
not difficult after a little experience in manipulating the gouge and
mallet, provided the gouge is kept sharp.

Small branches which have become infected should be cut off, the
cut being made wel' back of the disease—at least 2 or 3 inches, if
possible.

All cut-out areas and all the cut ends of stubs should be carefully
and completely painted with coal tar. A good grade of paint has

CHESTNUT TREE BLIGHT. 31

been recommended by some authorities as superior to tar, but it is
more expensive. If the tar is very thick, the addition of a little creo-
sote will improve it for antiseptic purposes as well as for ease in
applying. If the first coat is thin, a second one of fairly thick tar
should be applied within a few weeks or months. Other coats should
be applied lee whenever it becomes necessary.

The entire tree should be carefully examined for diseased spots and
every one thoroughly cut out and treated in the way already de-
scribed. In case of suspicious-looking spots a portion of the outer
bark can be cut out with the sharp gouge asa test. If this cut shows
the characteristically discolored Beak the spot can be considered as
diseased and cut out accordingly; if the cut shows healthy bark, it
need merely be treated with tar or paint, as other cuts are treated.
In examining a tree for diseased spots it is always best to begin at >
the base of the trunk and work up, for if the trunk is girdled at the
base it is useless to work anywhere on the tree.

When the spores of the fungus are present, especially in the form
of threads, or. ‘‘horns,”’ they are readily washed down the branches
and trunk by every rain, and are thus carried down to or toward
the base of the tree. As a result the base of a tree, the crotches, and
other places which afford easy lodgment for the spores are particu-
larly subject to infection.

Although spraying with any of the standard fungicides appears
to have no effect whatever in stopping the progress of the aeeenae
after it has once started in the inner or middle bark, there is little
doubt that it is of use in preventing infection from spores washed
down. by rain from the upper part of a tree or from spores which
have been transported from other trees. For this reason the spray-
ing, after each rain, of the parts of a tree below a spore-bearing
lesion is recommended, but only on an experimental basis. If no
spore-bearing lesions occur on the tree, there is less apparent reason
for spraying. The scattering of slaked lime about the base of a tree
and the whitewashing of the trunk and larger limbs have shown
apparently beneficial results in preventing infections and perhaps
also depredations of borers.

A tree which is being treated for individual infections must be
carefully watched and the diseased spots promptly cut out as they
appear. For this purpose each tree should be examined very care-
fully two or three times at least during the growing season.

The Department of Agriculture asks the cooperation of all persons
who have experimented with the disease in any way, and in return
is ready to give specific advice, based upon extensive experience with
the disease, as to the best methods of attempting its control or as to
what are likely to be the most profitable systematic observations or
experiments.

ADVICE TO CHESTNUT ORCHARDISTS.

In view of the uncertain future of the chestnut tree, the Depart-
ment of Agriculture advises against planting chestnuts anywhere east
of Ohio, at least until it is settled what efforts will be made by the
individual States to control the bark disease. The only exception is
that Japanese chestnuts may be grown if raised from imported seeds
and not grafted on American stocks. If the seed is raised in America,

32 CHESTNUT TREE BLIGHT.

the trees are more than likely to be hybrids with the American chest-
nut and to vary greatly in resistance to the bark disease. If grafted
on American stocks, the stocks readily succumb to the disease, and
so the whole tree is killed, no matter how resistant the scion-may be.
However, the nut of the true Japanese chestnut is of poor quality at
best, and it is an open question whether it can ever be made a com-
mercial success.

West of the natural range of the American chestnut, however, the
situation is quite different. Obviously the western chestnut orchard-
ist has before him a great opportunity. No matter how successful
efforts to limit the bark disease in the East may be, the nut crop will
be reduced for some years, and the business of growing fine orchard
chestnuts in the East will be depressed for the same length of time.
There is no apparent reason why, with rigid inspection, both of an
purchased stock and of the orchards themselves, all chestnut anaes
and nurseries from Ohio to the Pacific coast can not be kept perma-
nently free from the bark disease; therefore all persons interested in
growing the chestnut in the West as an orchard tree are earnestly
advised not to secure any chestnut nursery stock from eastern nur-
series; to be sure that stock from any source is rigidly inspected; to
watch with the utmost care their own nurseries and orchards; *and to
destroy immediately by fire any trees that may be found diseased.

There is presumptive evidence that the bark disease was introduced
into America on the Japanese chestnut, but until this point is defi-
nitely settled orchardists west of Ohio are advised not to import nur-
sery stock of this variety. Seed can probably be imported with a
reasonable degree of safety, however.

ADVICE TO OWNERS OF CHESTNUT WOODLAND.

Owners of chestnut woodland anywhere within the area of com-
plete infection are earnestly advised to convert their trees into lumber
as quickly as possible. The trees that are not already killed will soon
die in any case and the timber will quickly deteriorate in quality.
Such trees are a continual source of further infection, and, moreover,
large areas of dead chestnut trees, by harboring bark and wood
inhabiting insects, are likely to start some insect epidemic. Indeed,
with the quantity of dead chestnut timber now standing it will be
remarkable if some serious infestation of insects extending to sound
trees does not follow.

Owners of chestnut woodland outside the area of general infection
are counseled to watch for the first appearance of the disease, and
when it appears to cut down immediately all affected trees, bark
them, and burn the bark and brush, over the stump if practicable.
Such procedure will distinctly retard the spread of the disease in
that particular woodland, even if no concerted efforts at elimination
are made by neighboring owners. It is to be expected, however, that
in all cases of this kind the owner will have the cooperation of the
State authorities in a general quarantine movement.

It is almost needless to add that until we know what action is to
be taken in all the chestnut-growing States and what the results are
likely to be, chestnut woodland is a poor investment. Furthermore,
in forest management, as in improvement cuttings, etc., there should
be discrimination against the chestnut.

CHESTNUT TREE BLIGHT. 33

ADVICE TO OWNERS OF ORNAMENTAL CHESTNUT TREES.

Until the future of the chestnut tree is better known, or at least
until we know what legalized action is going to be taken in the
States concerned, the owners of chestnut-timbered land available for
building should pursue a very conservative policy. Houses should
not be located with sole reference to chestnut groves or to isolated
ornamental chestnut trees. Houses so located should be discrimi-
nated against in purchasing homes in so far as the death of the
chestnut trees soit injure the appearance of the place.

When ornamental trees become diseased they had better be cut
down at once and, if practicable, large trees of other species moved
in to take their places. In expert hands the moving of large trees is
a perfectly practicable and successful procedure and, although more
expensive, is much more satisfactory than waiting for nursery trees to
grow.

All owners of diseased ornamental chestnut trees are specifically
warned against ‘‘fake” tree doctors. Large sums of money have
been paid out in many cases for treatment that has been worse than
useless. Reliable tree specialists will have nothing to do with trees
affected with the chestnut bark disease, or, if they do anything, do it
with the distinct understanding in advance that it is entirely at the
owner’s risk. Of course, if an owner desires to employ tree surgeons
to experiment, that is another matter.

ADVANCING POPULAR KNOWLEDGE OF THE DISEASE.

In the localities where infection is general or complete (fig. 2)
everyone knows what the chestnut bark disease 1s and what its symp-
toms are and everyone appreciates its seriousness; but in these local-
ities it is too late even to attempt its control. On the other hand, in
Delaware, Virginia, West Virginia, western and southern Mary-
land, western Pennsylvania, central and northern New York, Massa-
chusetts, and Rhode Island very few people know the symptoms of
the disease. On this account no one notices it until it is thoroughly
established, and by the time public sentiment is sufficiently aroused
to authorize the necessary legislation and bring about united action
for public protection it is too late for such action to be of service.
Obviously, then, every effort should be made by all State and other
officials having such matters in charge to acquaint every citizen with
the prominent symptoms of the bark disease and to familiarize him
with the fact that unless prompt and united action is taken there
is every indication that the chestnut tree in the States above men-
tioned will become practically extinct within 10 years.

COOPERATION OF THE DEPARTMENT OF AGRICULTURE.

In this campaign of education the Department of Agriculture will
cooperate in the following ways: Copies of this bulletin or of other
publications of this department relating to the bark disease, and also

1In case such action is not immediately d2sirable or possible, a very good, though temporary, sceni¢e
effect can be obtained by lopping off the ends of the larger branches of the dead and dying chestnut trees,
removing the bark, and planting some rapid-growing vine at their foot, which soon covers them. One
of the best for this purpose is the Japanese kudzu vine (Pueraria thumbergiana (S. and Z.) (Benth.), on
account of its extraordinarily rapid growth. Such vine-covered stumps must be carefully watched, how-
ever, for in a very few years they decay and are liable to be blown over.

43017°—S. Doc. 653, 62-2 3

-

34 CHESTNUT TREE BLIGHT.

typical specimens of the disease, will be sent to any person applying
for them. Two specimens will be sent to each person—one showing
the appearance of the disease on smooth bark, and the other the later
development of the fungus on thick bark. In both these specimens
the fungus will have been killed by soaking in formalin to insure
against any infection from this source.

So far as the supply permits, lantern slides and photographs will,
upon application, be loaned for special lectures, exhibits, etc., to the
o‘ficers of States, experiment stations, colleges, and schools where
agriculture is taught, as well as to tree wardens and other officials
whose work may bear directly upon local campaigns of publicity.

This department will always examine any suspected specimens of
this disease sent to Washington by mail, and will report the findings
as promptly as possible. Before sending specimens, however, all
persons are urged to read the paragraphs on symptoms on pages 6 to
9 in order to select the specimens intelligently. For example, if the
end of a girdled and withered branch is sent, it is not possible to make
a dependable diagnosis unless a portion of the girdling area happens
to be included. This is the eal part where the fungus is surely
present, and the fungus itesif must be seen in order to be absolutely
sure of the disease. Portions of the bark that show the small orange
or reddish-brown pustules, about the size of the head of a pin, should
always be sent, if these can befound. These commonly occur near the
lower edge of the girdling area.

PUBLIC COOPERATION.
With many people familiarized with the appearance of the chest-

nut-bark disease and its possibilities of harm, the disease will be
noticed and stamped out by private effort in many places when it

first appears and the public will understand and be ready to cooper-

ate in any official measures of control as soon as these become neces-
sary in any locality.

All possible forces must be enlisted in a campaign of publicity.
The cooperation of all newspapers, particularly local papers, can be
easily secured in all the States where the chestnut is an important
tree. A portion of the program for Arbor Day, 1912, should be
devoted to a consideration of this disease. Teachers of nature study,
botany, or agriculture in the public schools can do great service by
teaching their pupils how to recognize the disease and by training
them to be on the lookout for its first appearance in the home com-
munity. Such a body as the “ Boy Scouts” can, if properly trained,
become in every community a most efficient force for locating the
disease. The boys will readily appreciate that such work is real
“scouting” against a most insidious and destructive public enemy.
And, finally, many private owners of chestnut trees will be eager to
cooperate with the State authorities in the early elimination of
advance infections if only they are able to recognize such infections.

THE PROTECTION OF THE SOUTHERN STATES.
Tt must be remembered that the bark disease has as yet done only a

small fraction of the damage that it is undoubtedly capable of doing.
The best chestnut timber of America is south of the Potomac River

CHESTNUT TREE BLIGHT. 35

and there the park disease is present in only a few spots. For this
reason it is of extraordinary importance that these few spots be eradi-
cated and that the disease be soon controlled immediately north of
the Potomac. If the bark disease once becomes well established in the
chestnut forests of the South, it will be well-nigh impossible to control
it, on account of the sparsely settled and mountainous condition of
much of that country and for other reasons which do not obtain
farther north.

SUMMARY.

(1) The chestnut-bark disease was first noted near New York
City in 1904 and is now present in at least 10 States. It attacks the
American chestnut, the European chestnut, the chinquapin, and,
rarely, the Japanese chestnut.

(2) The total financial loss from this disease is now estimated at
$25,000,000.

(3) The disease is caused by a fungus, and the entrance of a spore
at any point where the bark is broken may cause infection. The
disease spreads primarily in the inner bark and produces character-
istic lesions eich girdle the tree at the point attacked.

(4) Conspicuous symptoms are the development of bunches of
sprouts below the girdling lesions; the half-formed yellowish leaves
in the spring on the previously girdled branches, the reddish-brown
leaves on branches girdled in summer, and the yellow, orange, or
reddish-brown pustules of the fruiting fungus on the bark. It is
' practically useless to attempt systematic location of the disease from
October to April, inclusive.

(5) The spores may be carried considerable distances on chestnut
nursery stock, tan bark, and unbarked timber; also by birds, insects,
squirrels, etc., which have come in contact with the sticky spore
masses. Water quickly dissolves these spore masses and the minute
spores are in this way carried along with water, as, for instance, with
rain water running down a tree. Borers’ tunnels form the most
common places of entrance for spores.

(6) The only known practical way of controlling the disease in
a forest is to locate and destroy the advance infections as soon as

ossible after they appear and, if the disease 1s well established near

y, to separate the area of complete infection from the comparatively
uninfected area by an immune zone. Advance infections should be
located by trained observers and destroyed by cutting and burning.
As the disease develops almost entirely in the bark, this must be com-
pletely destroyed (burned).

(7) In order to carry out the above methods it is essential that
the several States concerned secure necessary legislation and appro-
priations, following the example of Pennsylvania, as no law exists
whereby the Federal Government cans undertake such work and
cooperation among private owners without State supervision is
impracticable.

8) Chestnut nursery stock should be rigidly inspected for the
disease and only perfectly healthy plants passed.

(9) The life of valuable ornamental trees may be greatly prolonged
by promptly cutting out all diseased areas and removing all disease-
girdled branches and then covering the cuts with tar. Spraying is

36 CHESTNUT TREE BLIGHT.

of no use in stopping the fungus after it has once started growth in
the bark.
(10) It is recommended that owners of infected woodland cut
down and utilize the diseased chestnut timber as soon as possible.
(11) For the present the planting of chestnuts anywhere east of
Ohio‘is not advised, but there is no apparent reason why chestnut
orchards west of Ohio may not be kept free from the disease.

O

Senate Document No. 653, 62-2. PLATE I.

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KNOWN DISTRIBUTION OF THE CHESTNUT BARK DISEASE FEBRUARY 1, 1912.

[Horizontal lines show the botanical distribution of the American chestnut tree. Dots repre-
sent advance infections. Thicker lines, arranged concentrically about New York City,
show various degrees of general infection and death.]

Senate Document No, 653, 62-2. PLATE Il.

Fic. 1.—TYPICAL GROUP OF LARGE CHESTNUT TREES DYING WITH THE BARK
DISEASE. NEAR BROOKVILLE, N. Y.

[Note appearance of foliage. ]

Fila. 2.—DEAD CHESTNUT TREES ALONG A BOULEVARD, NEAR RICHMOND HILL,
NieYe

[Note healthy condition of trees of other species. |

Senate Document No. 653, 62-2. PLATE III.

Fic. 1.—THE MOST SOUTHERN POINT OF INFECTION—A GROUP OF DISEASED
CHESTNUT TREES AT FONTELLA, BEDFORD COUNTY, VA.

Fia. 2.—FOREST TREE NEARLY DEAD. PARKTON, MD.
[Note characteristic sprouts and dwarfed leaves of the only surviving branches.]

Senate Document No. 653, 62-2. PLATE IV.

FIG. 1.—TREE WITH SOME LARGE BRANCHES GIRDLED, WESTBURY, N. Y.

[Note appearance of foliage. ]

Fia. 2.—TREE WITH SMALL BRANCHES GIRDLED, BUCK, PA.

[Note appearance of foliage. ]

Senate Document No. 653, 62-2. PLATE V

COMPLETE DESTRUCTION OF CHESTNUT TREES IN MIXED STAND.

[Note healthy condition of trees of other species. Views along the Long Island Railroad.]

No

Senate Document No. 653, 62-2.

PLATE VI.

Fi@. 1.—COMPLETE DESTRUCTION OF CHESTNUT TREES IN NEARLY PURE STAND.

[Many of the trunks have been dead long enough to shed their bark. Near Brooklyn, N. Y.]

Fia. 2.—COMPLETE DESTRUCTION OF CHESTNUT TREES IN A NEARLY PURE STAND.

[Note healthy condition of other species. Forest Park, near Brooklyn, N. Y.]

PLATE VII.

Senate Document No. 653, 62-2.

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Senate Document No. 653, 62-2. PLATE VIIf.

GRAFTED VARIETIES OF ORCHARD CHESTNUTS, NEARLY DEAD. MARTIC FORGE, PA.

[Note the suckers on the trunk and the appearance of the foliage. ]

Senate Document No. 653, 62-2, PLATE IX

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Fia. 1.—EARLY STAGE OF DISEASE. INFECTION OF A SMALL BRANCH IN THE TOP
OF THE TREE. WESTBURY, N. Y.

Fic. 2.—EARLY STAGE OF DISEASE. END OF BRANCH GIRDLED AT UPPER RIGHT-
HAND OF PICTURE. LANCASTER COUNTY, PA.

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Senate Document No. 653, 62-2. PLATE Xl.

DEAD CHESTNUT TREES, WITH BARK IN SUCCESSIVE STAGES OF DECAY, SHOWING
PUSTULES OF THE FUNGUS IN WHICH THE WINTER SPORES ARE BORNE.

Senate Document No. 653, 62-2. PLATE XII.

LATE STAGES OF DECAY OF BARK AND OuTER LAYERS OF Woob.

Senate Document No. 653, 62-2. PLATE XIill.

Fic. 1.—DEAD AND DYING SPROUT GROWTH, PORT JEFFERSON N. Y.

[Note healthy condition of trees of other species. ]

Fic. 2.—TYPICAL GROUP OF DEAD CHESTNUT TREES. NEAR BROOKLYN, N. Y.

[Note dead suckers on the trunks. From left toright: The first trunk shows the disease
less than 1 year old: the second from 2 to 3 years old; the third 4 or more years old;
and the fourth about 3 years old.]

Senate Document No, 653, 62-2. PLATE XIV.

Fic. 1.—EXTERNAL APPEARANCE OF A YOUNG LESION OF THE CHESTNUT BARK
DISEASE, SHOWING THE SPREAD OF THE DISEASE FROM AN INSECT PUNCTURE.

Fia. 2.—THE SAME AS FIG. 1, WITH THE OUTER BARK REMOVED TO SHOW THE
CENTRIFUGAL SPREAD OF THE MYCELIUM OF THE PARASITIC FUNGUS.

Senate Document No. 653, 62-2, PLATE XV.

SMALL CHESTNUT TREE IN POT ABOUT 3 MONTHS AFTER ARTIFICIAL INOCULATION WITH
SUMMER SPORES FROM A PURE CULTURE OF THE FUNGOUS PARASITE. TREE GIRDLED
AT BaSE, LEAVES ABOVE WITHERED; VIGOROUS SUCKERS GROWING UP FROM BELOW
GIRDLED POINT.

Senate Document No. 653, 62-2. PLATE XVI.

EXAMPLES OF TREE SURGERY, SHOWING HEALING PROCESSES AFTER CUTTING
OuT LESIONS, IN TREATMENT OF ORCHARD TREES.

Senate Document No. 653, 62-2. PLATE XVII.

FiG. 3.—PART OF A DISEASED BRANCH OF A CHESTNUT TREE, SHOWING
TYPICAL PUSTULES AND ForRM OF Spore DISCHARGE IN DAMP WEATHER.

[Magnified 3 diameters. ]

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