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Full text of "Carnation stem-rot and its control"

THE UNIVERSITY 

OF ILLINOIS 

LIBRARY 



AGRICULTURAL 
LIBRARY 



UNIVERSITY OF ILLINOIS 




BULLETIN No. 223 



CARNATION STEM ROT AND ITS CONTROL 



BY GEORGE L. PELTIER 




URBANA, ILLINOIS, SEPTEMBER, 1919 



CONTENTS OF BULLETIN No. 223 

Page 

INTRODUCTION 579 

Stem Kot in Illinois , 579 

Symptoms of the Disease 581 

Carnation Branch "Rot 583 

Infection 583 

A STUDY OP THE CONDITIONS INFLUENCING THE GROWTH OF PARASITE AND 

HOST 584 

The Fungus in Pure Culture 585 

Persistence of the Fungus in Soils 586 

Influence of Manures 586 

Commercial Fertilizers 587 

Acidity and Alkalinity of the Soil 588 

Replanting 593 

Temperature 593 

Soil Moisture 595 

ATTEMPTS TO CONTROL STEM EOT IN THE GREENHOUSE BY DISINFECTION AND 

STERILIZATION OF THE SOIL 599 

Disinfection of the Soil -. 599 

Steam Sterilization 602 

CONCLUSIONS AND RECOMMENDATIONS . 606 



BY GEORGE L. PELTIER, ASSOCIATE IN FLORICULTURAL PATHOLOGY 1 

INTRODUCTION 

Carnation growing as a specialized industry in Illinois has assumed 
considerable proportions since its inception thirty years ago. It began 
in the vicinity of Chicago and the industry is still centered there. 
Other large establishments are scattered thruout the state, and no 
local florist is without a few benches of these plants. Accurate 
statistics are not available, tho it is a fair estimate to place the num- 
ber of carnation plants grown in Illinois for the trade in a single 
year at five million in the field and three million under glass. 2 Allow- 
ing three-fourths of a square foot for each plant, the total number 
of plants under glass would represent an area of about two million 
square feet, which is approximately one-fifth the total area of glass 
in Illinois. It is thus evident that several millions of dollars are 
invested in the carnation industry in Illinois. 

The carnation plant is attacked by a number of fungous diseases, 
several of which occasionally result in an appreciable loss to the 
grower. Perhaps the most serious of these is carnation stem rot. 
The following pages are devoted to a description of some experi- 
mental work undertaken by the author with the view of controlling 
this disease. A short discussion of the results, with recommenda- 
tions, is given at the end of the bulletin. 

STEM ROT IN ILLINOIS 

Carnation stem rot is caused by the attacks of a soil fungus, 
Rhizoctonia Solani Kiihn (Corticium vagum B. & C.). 3 

The disease is widely scattered thruout the state, in fact, it is 
present to some extent in every greenhouse where carnations are 
grown. The controlling influences in the occurrence of stem rot ap- 
pear not to be due to unequal distribution of the fungus, but to be 
more closely related with climatic and edaphic conditions favorable to 

a Since September 1, 1916, Plant Pathologist, Ala. Agr. Exp. Sta., Auburn, 
Alabama. 

2 Based upon replies to a questionnaire sent in 1915 to all Illinois growers 
having 5,000 square feet of glass or more. 

8 A complete description of the general characters of this fungus, together 
with a historical account, its distribution, hosts, etc., will be found in Bulletin 
189 of this station. 

579 



580 



BULLETIN No. 223 



[September, 



the spread and development of the fungus, together with the condition 
of the plant. 

The losses from carnation stem rot are not often very great. 
However, under conditions favorable to the rapid development and 
spread of the fungus, it becomes a destructive parasite. Under 
such conditions, many cuttings may be destroyed in a short time 
and many plants also lost, both in the field and later in the benches. 
In isolated cases the loss may be as high as 50 percent of the cut- 
tings. The percentage of loss may be equally high in the field and 
in benches. The average loss from season to season of course is 
much lower. From replies to questionnaires sent out by the writer 
to carnation growers in the state, it was learned that the percent- 
age of loss varies from .1 percent to 20 percent, with an average 
of 2.2 percent in the greenhouse and 3.25 percent in the field. In 
two of the experimental houses at the Illinois Experiment Station the 
loss averaged nearly 2 percent a year for a period of five years (see 
Table 1). 

TABLE 1. Loss FROM CARNATION STEM ROT IN THE EXPERIMENTAL HOUSES 

NOS. 1 AND 2, FOR A PERIOD OF FlVE YEARS 



Season 


Date of planting 


No. of 

plants 


Total 
loss 


Percentage 
loss 


1909-10 


Sept. 9-13 


3200 


33 


1.03 


1910-11 


Sept. 9-12 


3200 


27 


.84 


1911-12 


Aug. 8-10 


3200 


49 


1.53 


1912-13 


Aug. 7-8 


3200 


99 


3.09 


1913-14 


Aug. 12-14 


3200 


86 


2.70 



Practically all the soil used by the grower is inhabited to some 
extent by this fungus. The fungus is, in all probability, endemic, 
that is, it has not been introduced into the state with carnation 
plants but existed in the soils of Illinois before carnations were 
grown. This statement is supported by the fact that diseases due 
to the fungus are prevalent thruout the United States on many 
plants, and the fungus itself is found in many foreign countries. 

The fungus may live purely as a saprophyte in the soil, getting 
its nourishment from dead organic materials, or it may be parasitic, 
that is, living on and getting its sustenance from growing plants. 
In a previous publication 1 the writer has shown that the fungus 
may attack a large group of plants, including vegetable and field 
crops, herbaceous plants, and weeds, besides many plants grown 
under glass. 

The wide distribution, the many hosts, and the repeated reports 
of the destructiveness of the stem-rot organism prove very conclu- 
sively that it persists indefinitely under diverse conditions in arable 



J Loc. cit. 



1919] . CARNATION STEM EOT AND ITS CONTROL 581 

soils. However, it is only when conditions are favorable for its 
development that it becomes an active parasite. Owing to this fact, 
it is not .as serious as some of the Fusarium wilts, which once intro- 
duced into a locality, increase in severity each season until the 
growing of the crops attacked by them must be abandoned. 

SYMPTOMS OF THE DISEASE 

Stem rot may attack seedlings, cuttings, or mature plants. In 
ail cases the symptoms are more or less alike. When seedlings become 
affected (a condition commonly known as "damping-off "), lesions ap- 
pearing as small brown spots are seen on the stem at the surface 
of the soil. The lesions increase in size, eventually almost girdling 
the stem and causing the collapse of the seedling. In severe cases 
the prostrate seedlings may later appear overgrown with a mat of 
brown strands made up of the mycelium of the fungus. 

Cuttings are attacked several days after they have been placed 
in the sand. As in the case of seedlings, the cutting is attacked on 
the stem just above, or frequently just below, the surface of the sand. 
The leaves wilt, the cutting falls over, and a soft, wet, progressive 
rot may develop at the callus and extend to the surface of the sand, 
or lesions of various sizes may be formed at any point. 

Stem rot occurs to some extent on the young plants in pots. 
The source of this infection is either in the use of diseased cuttings 
or of contaminated pots. On pulling up these plants it is found that 
stem rot usually starts from a small lesion which increases in size 
until the stem is girdled. 

The symptoms shown by a mature plant attacked by the disease 
are very characteristic (Fig. 1). The fungus enters the stem at a 
point just below the surface of the soil. The foliage becomes pale, 
gradually losing the green color. In a few days or a longer period, 
depending upon the condition of the weather, this is accompanied 
by wilting. An examination of the stem at the surface of the soil 
reveals at this time a slimy, wet condition under the bark, which 
gives this rot its characteristic name. A slight twist is sufficient to 
slough off the bark and expose the harder tissues underneath. A plant 
at this stage may as well be pulled and removed, for it has been in- 
jured beyond recovery. 

The fungus evidently enters the plant thru the cracks in the 
corky layer of the bark at a point near the surface of the soil. After 
passing thru the bark it attacks the growing layer of cells, the cam- 
bium. From this tissue the mycelium passes into the woody tissues 
and can be found even in the pith. It is at this time that wilting 
becomes evident. During later stages, sclerotia, which are small com- 
pact masses of mycelium, are formed on the center portions of the 
stem and these become quite evident to the unaided eye. 



582 



BULLETIN No. 223 



[September, 




FIG. 1. CARNATION PLANT SHOWING THE CHARACTERISTIC SYMPTOMS OF STEM EOT 



1919] CARNATION STEM EOT AND ITS CONTROL 583 

CARNATION BRANCH ROT 

There is but one carnation disease which may be mistaken for 
stem rot. To this disease the writer several years ago applied the 
.term "branch rot". Before that time the two diseases were com- 
monly known as wet stem rot and dry stem rot. In order to avoid 
confusion of these two terms, the term stem rot was adopted for the 
disease caused by Rhizoctonia and the name branch rot adopted to 
replace the term dry stem rot. 

Branch rot is caused by the fungus Fusarium. This disease affects 
the host plant much more slowly than does stem rot. There is no 
noticeably rapid wilting of the foliage of the entire plant. Infection 
does not, as a rule, take place at or near the surface of the soil but 
may take place at any point where the tissues have been broken. 
Branch rot is essentially a wound disease. Wherever a branch or 
leaf has been broken or removed, the disease may gain entrance. In- 
fected parts turn yellow, wilt, and become dry. A single branch may 
thus be affected, while the rest of the plant appears healthy and 
normal. There is no soft and slimy area on the stem, as is found in 
stem rot, but instead the stem remains dry and tough. Occasionally 
both diseases occur on one and the same plant. 

In the cutting bench the two diseases are not so easily distin- 
guished. However, careful observations will show that in the case 
of branch rot the foliage is most often affected and very little rotting 
is evident at or below the surface of the soil. In the case of stem 
rot, on the other hand, the disease is noticeable on parts of the plant 
at or below the surface of the soil. 

INFECTION 

Mature Plants. As said above, stem rot attacks seedlings, cuttings, 
and mature plants. Mature plants may become infected either in 
the field or in the greenhouse. From observations in the carnation 
field during four summers it has been found that, altho always present 
in the soil, the fungus attacks plants only under certain conditions. 
One of these conditions is the presence of wounds. Many counts in 
the field have brought to light the fact that plants with a single 
central stem, breaking one to two inches above the soil, are less 
frequently infected than are plants forking just at or slightly below 
the soil surface. The branches of the latter are easily broken during 
cultivation and many infections have been traced to such wounds. 

Stem rot is more prevalent during a hot, sultry, wet season. Such 
a season produces large, bushy plants, with much soft growth. It is 
very probable that infection takes place more readily under such 
conditions. 



584 BULLETIN No. 223 [September, 

Perhaps the most critical period of the mature plant is at the 
time when it is transferred from the field to the house. The growth 
of the plant at this time is more or less checked, and unless the weather 
is cool the temperatures of the house may be unfavorably high. It 
is at this time, or shortly after, that large losses due to Rhizoctonia" 
occur. Losses at this time are unquestionably due to changed condi- 
tions, more or less abnormal until the plant has again become estab- 
lished, and to unavoidable injuries to the plant, such as breaking of 
branches, etc., during the process of transplanting. 

Cuttings. Cuttings in the sand succumb very rapidly to attacks 
of Rhizoctonia. The fungus may be introduced into the cutting bench 
by means of cuttings taken from plants already infected. Cuttings 
taken from the lower portions of the stock plant are most likely to 
harbor the fungus, especially when the leaves have been in contact 
with soil. Unclean sand also may be the means of infection. The 
source of sand used in the cutting bench is of much importance. 
Sand used previously for cuttings, unless disinfected, may harbor 
the fungus, which, when conditions are favorable, may become active 
and attack many cuttings. 

After the rooted cuttings have been transferred to pots, losses are 
not frequent. Individual plants may be destroyed by the disease, but 
such infection cannot be carried readily to adjacent plants. If the 
rooted cuttings are transplanted into flats, the losses frequently are 
more extensive, for a single infection may readily be carried to a 
number of plants. 

A STUDY OF THE CONDITIONS INFLUENCING THE 
GROWTH OF PARASITE AND HOST 

In attempting to combat a fungous disease, such as stem rot 
of carnations, two possible courses are open; either the fungus must 
be eradicated from the soil or, if that is not possible, some method 
must be found to reduce its destructiveness to a minimum. Attempt- 
ing the latter, two more or less clearly defined methods of procedure 
are possible; either the fungus must be placed in an environment 
which, being unfavorable, will greatly reduce its virulence but at 
the same time approximate rather closely the optimum conditions for 
the carnation plant, or carnation plants must be developed which are 
to a high degree immune from the attacks of the fungus. 

A series of experiments was undertaken by the author with the 
view of ascertaining some of the conditions which influence the 
growth of the fungus ; also the effect of these on its parasitism. Sim- 
ilar studies were made of possible methods of eradicating the fungus 
from soil in greenhouses. 



1919] CARNATION STEM EOT AND ITS CONTROL 585 

THE FUNGUS IN PURE CULTURE 

Temperature. In pure culture in the laboratory it was found that 
the fungus grows slowly at relatively low temperatures. At higher 
temperatures growth is more rapid, the most rapid growth taking 
place at approximately 86 degrees Fahrenheit. 

Moisture. It was found also that the fungus responds in a simi- 
lar way to moisture conditions. In relatively dry sand it makes 
good subsurface, growth. In wet sand growth is on the surface of 
the sand. This is probably correlated with aeration, especially 
with the supply of oxygen. Practically all injury caused by Rhi- 
zoctonia occurs at or near the surface of the soil and rarely below 
three or four inches, except perhaps in seed beds in which sand is 
used. This fact has already been discussed in detail in Bulletin 189, 
already referred to. 

The stem-rot organism is very resistant to unfavorable external 
conditions, such as low temperature and drying. An experiment was 
carried out by placing a set of flasks partially filled with sand which 
was inoculated with the fungus, in the open field. Another set of 
flasks containing some of the inoculated sand was placed in the green- 
house, while a third was kept in the laboratory. At different times 
during the winter months the flasks were weighed to determine the 
loss in water content. Cultures of the fungus also were made at 
the same time to determine whether it was still living. During the 
interim a minimum temperature of 12 degrees Fahrenheit below 
zero had been registered, and several flasks in the open field had 
been broken by the frost. In all cases the flasks had lost from 25 to 
50 percent of their original weight. However, in every case the 
fungus survived and was able to make normal growth when trans- 
ferred to more favorable conditions. 

Cultures were made from flasks kept in the laboratory for two 
years and two months after they had been placed there, and the 
fungus was still alive. The sand at this time was dry and hard. 

Thus, low temperatures and drying appear to have little or no 
effect on the vitality of the fungus. 

Acidity and Alkalinity. As a number of writers have recom- 
mended the use of lime for the control of stem rot, the effects of 
acidity and alkalinity on the growth of Rhizoctonia in pure culture 
were tested out in the laboratory. String-bean agar was made acid 
and alkaline to various degrees, inoculated, and measurements of the 
growth of the mycelium taken from day to day. The results showed 
that Rhizoctonia can grow on medium which, is, within reasonable 
limits, either acid or alkaline in reaction. 



586 



BULLETIN No. 223 



[September, 



PERSISTENCE OF THE FUNGUS IN SOILS 

Fortunately most growers renew the soil in the benches each sea- 
son. However, as some growers use the same soil, during a second 
season, a knowledge of whether the stem-rot fungus will persist in 
the soil in the bench from one year to the next is of importance. 

A five-foot section (No. 113) in the greenhouse was filled with 
soil taken from a bench in which carnations had been grown the 
previous season. The bench was planted to twenty Beacon carnation 
plants. A similar section (No. 112) was filled with fresh soil taken 
from a field that had been in sod for a number of years. This section 
was also planted to twenty Beacon plants. The two sections received 
similar treatment in the application of fertilizers and the cultural 
methods were uniform. 

During the entire growing season one plant died of stem rot in 
the section containing fresh soil (No. 112). Eight plants were lost 
in the section in which old soil was used (No. 113). The results are 
tabulated in Table 2. 



TABLE 2. EFFECT OF PLANTING CARNATIONS IN OLD INFECTED SOIL USED 
THE PREVIOUS SEASON: 1912-13 



Sec- 
tion 


Treatment 


Number of 
diseased 
plants 


Number of 
healthy 
plants 


Percentage 
loss 


113 


Old soil 


8 


12 


40.0 


112 


New soil 


1 


19 


5.0 



The data show clearly that Rhizoctonia persists in the old soil 
of the benches from year to year. The evidence also seems to indi- 
cate that the disease becomes more virulent in the soil the second 
season. 

INFLUENCE OF MANURES 

To determine whether Rhizoctonia is introduced in the bench thru 
the use of manures, comprehensive experiments were carried on dur- 
ing the seasons 1912-13 and 1913-14, with negative results. 

Since greenhouse soils receive, previous to the filling of the benches, 
heavy applications of manures, it is not improbable that such soils 
offer a good environment for the rapid growth of the fungus and 
present conditions conducive to its attack on the plant. A compari- 
son in this respect was therefore made between soils containing no 
manure and soils receiving applications of different amounts of 
manures. Eight five-foot sections were filled with soil, manure was 
added to and incorporated with the soil of six of them, while two 



1919] 



CARNATION STEM ROT AND ITS CONTROL 



587 



sections received no manure. Each section was inoculated with the 
fungus by mixing with the soil about a bushel of infected soil taken 
from benches in the experimental house where plants had previously 
succumbed to the disease. Twenty-five plants (variety Rosette) were 
planted in each section and uniform treatment given. 

TABLE 3. RELATION OF VARYING AMOUNTS OF MANURE IN THE SOIL TO 
THE VIRULENCE OF STEM ROT: 1914-15 



Sec- 
tion 


Treatment 


Number of 
healthy 
plants 


Number of 
diseased 
plants 


Percentage 
loss 


254 
255 


Check: no fertilizer or manure 
20 pounds of manure 


22 
20 


3- 
5 


12.0 
20 


256 


40 pounds of manure 


25 





0.0 


257 


80 pounds of manure 


21 


4 


16.0 


258 


160 pounds of manure 


18 


7 


28 


259 
260 


Check: no fertilizer or manure 
40 pounds of manure 


21 
25 


4 



16.0 



261 


80 pounds of manure 


8 


17 


68.0 



The data shown in Table 3 are someAvhat contradictory. On 
the whole it seems that manure added to soil has little influence on 
the growth and parasitism of the fungus. 

COMMERCIAL FERTILIZERS 

Table 4 contains data of plants growing in soils treated with 
commercial fertilizers. The sections in the experiment were inocu- 
lated with the fungus by adding to each a pint of a mixture of sand 
and corn meal in which the fungus was growing. Twenty-five Rosette 
carnations were planted in each section. 



TABLE 4. RELATION OF EXCESSIVE AMOUNTS OF COMMERCIAL FERTILIZERS 
TO THE VIRULENCE OF STEM ROT IN THE GREENHOUSE: 1914-15 



Sec- 
tion 


Treatment 


Number of 
healthy 
plants 


Number of 
diseased 
plants 


Percentage 
loss 


246 


Check : no fertilizer 


8 


17 


68.0 


247 

248 


Dried blood 1 pound per week. . 
Potassium sulfate 1 pound per 
week 


7 
18 


18 

7 


72.0 
28.0 


249 
250 

251 

252 
253 


Dried blood 1 pound per week 
and 4 pounds limestone 1 .... 
Potassium sulfate 1 pound per 
week and 4 pounds limestone 1 
Ammonium sulfate 1 pound 1 . . . 
Ammonium sulfate 2 pounds 1 . . 
Ammonium sulfate 4 pounds 1 . . 


10 

9 
14 
9 
6 


15 

16 
11 
16 
19 


60.0 

64.0 
44.0 
64.0 
76.0 



limestone and ammonium sulfate turned into soil before setting plants. 



588 



BULLETIN No. 223 



[September, 



The data do not show any close relation between the use of com- 
mercial fertilizers and infection. In most cases the commercial 
fertilizers were used in excessive amounts. This in all probability' 
had an influence on infection as a whole, for excessive amounts added 
to soil lower the vitality of the carnation plant. This was noticeable 
in the sections to which potassium sulfate was added, the plants show- 
ing the usual symptoms of overfeeding with potassium. The plants 
of Sections 252 and 253 also showed clearly the effects of the large 
amounts of ammonium sulfate used. The large application of dried 
blood in Section 247 showed its effects on the physical structure of 
the soil and the plants did not make normal growth. The high per- 
centage of infection in these sections is in all probability correlated 
with the weakened condition of the plants. Nevertheless, the per- 
centage of loss in the untreated soils of the check sections was high, 
so that no definite conclusions can be drawn from the results. 



ACIDITY AND ALKALINITY OF THE SOIL 

In 1912 limestone was tested out next to a section in which sulfuric 
acid was used as a possible control measure. Both of these methods 
failing as far as control was concerned, the experiments were carried 
out thru two more seasons to test out the effects of alkalinity and 
acidity of the soil and its relation to stem rot. 

A solution of sulfuric acid was prepared and applied to soil of a 
five-foot section at the rate of three-sixteenths fluid ounce per square 
foot. One day previous, the soil was inoculated with Rhizoctonia 
by mixing with it a pint of infected soil. Two days after the acid 
treatment, the section was planted to twenty carnation plants (variety 
Beacon) . 

A second section was inoculated and planted the same as the 
first, while a third was inoculated and five pounds of crushed lime- 
stone (applied at the rate of five tons to the acre) was thoroly mixed 
with the soil two days later. A combination of the acid-limestone 
treatment was applied to a fourth section. The soil in this section 
also was inoculated and allowed to stand for a day. The sulfuric- 

TABLE 5. EFFECTS OF ACIDITY AND ALKALINITY ON THE VIRULENCE OF 
STEM ROT IN THE GREENHOUSE: 1912-13 



Sec- 
tion 


Treatment 


Number of 
healthy 
plants 


Number of 
diseased 
plants 


Percentage 
loss 


109 


Sulfuric acid, , 3 8 fluid ounce 
per square foot . 


7 


13 


65 


110 


Check 


16 


4 


20.0 


111 


Limestone 5 pounds 


19 


1 


5.0 


119 


Sulfuric acid plus 5 pounds 
limestone 


15 


5 


25.0 



1919] 



CARNATION STEM EOT AND ITS CONTROL 



589 



acid solution was then applied, and on the second day after five 
pounds of crushed limestone was mixed with the soil. 

The results shown in Table 5 indicate that the acid solution did 
not control the amount of stem rot. Tests made frequently during 
the course of the season gave good acid reactions. The addition of 
crushed limestone, however, appears to have checked stem rot. 

The above experiment, with some modifications, was repeated dur- 
ing the seasons 1913-14 and 1914-15. For the first season the same 
amounts of acid and limestone were used, while for the second season, 
these amounts were doubled. The experiment was divided into six 
treatments, two five-foot sections being devoted to each treatment. 
Each section was planted to twenty-five plants (variety White En- 
chantress) and all given the same conditions thruout the season. 
Before planting, the sections were treated as follows: 

Two sections were inoculated with a soil culture of Rhizoctonia, 
allowed to stand for several days, and then given an application of 
sulfuric acid at the rate of three-sixteenths fluid ounce per square 
foot. In 1914-15 this rate was doubled. Two other sections were 
given an application of sulfuric acid at the above rate, allowed to 
stand for three days, and then inoculated with a soil culture of 
Rhizoctonia. The rate of application was doubled in 1914-15. To 

TABLE 6. EFFECTS OF ACIDITY AND ALKALINITY ON THE VIRULENCE OF 
STEM ROT IN THE GREENHOUSE: 1913-14 



Sec- 
tion 


Treatment 


Number of 
healthy 
plants 


Number of 
diseased 
plants 


Total 
diseased 


Percentage 
loss 


167 
173 

168 
174 

169 
175 

170 
176 

171 

177 

172 

178 


Inoculated. Acid treat- 
ment 


5 

1 

11 

24 

25 
25 

1 


4 
16 

25 
25 


20 
24 

14 
1 




24 
25 

21 
9 





44 

15 


49 
30 



88.0 

30.0 
0.0 

98.0 
60.0 
0.0 


Inoculated. Acid treat- 
ment 


Acid treatment. Inocu- 
lated 


Acid treatment. Inocu- 
lated 


Acid treatment. Check . . . 
Acid treatment. Check. . . 

Inoculated. Limestone 
(5 pounds) 


Inoculated. Limestone 
(5 pounds) 


Limestone (5 pounds). 
Inoculated 


Limestone (5 pounds). 
Inoculated 


Limestone (5 pounds). 
Check 


Limestone (5 pounds). 
Check 



590 



BULLETIN No. 223 



[September, 




FIG. 2. VIRULENCE CF STEM ECT IN THE GREENHOUSE IN AN ACID SOIL 

(Photographed Sept. 20, 1914) 
Section 236 Inoculated. Acid Treatment 
Section 237 Acid Treatment. Inoculated 
Section 238 Acid Treatment. Check 



1919] 



CARNATION STEM EOT AND ITS CONTROL 



591 




FIG. 3. AN ALKALINE SOIL INEFFECTIVE IN CONTROLLING THE VIRULENCE OF STEM 

EOT IN THE GREENHOUSE (Photographed Sept. 20, 1914) 

Section 239 Inoculated. Limestone 

Section 240 Limestone. Inoculated 

Section 241 Limestone. Check 



592 



BULLETIN No. 223 



[September, 



two other sections sulfuric acid was applied at the same rate as 
above and allowed to stand several days. Six additional sections 
were treated in the same way as the six sections above, except that 
the acid treatment was in each case replaced by 5 ^pounds of crushed 
limestone. In the 1914-15 experiments 10 pounds of crushed lime- 
stone was used instead of 5 pounds. The results of these experi- 
ments are summarized in Tables 6 and 7 (see also Figs. 2 and 3). 

Under the conditions of the above experiments, neither sulfuric 
acid nor lime had a controlling effect on stem rot. The fungus seemed 
to thrive equally well in an acid soil and in an alkaline soil. This 
result has been corroborated by growing the fungus in the laboratory 
on culture media of definite, known acidity and alkalinity; within 
certain limits the fungus showed but little preference for either sub- 
stratum. 



TABLE 7. EFFECTS OF ACIDITY AND ALKALINITY ON THE VIRULENCE OF 
STEM ROT IN THE GREENHOUSE: 1914-15 



Sec- 
tion 



Treatment 



Number of 
healthy 
plants 



Number oi 

diseased 

plants 



Total 
diseased 



Percentage 
loss 



230 Inoculated. Acid treat- 

ment 6 

236 Inoculated. Acid treat- 

ment 4 

231 Acid treatment. Inocu- 

lated 5 

237 Acid treatment. Inocu- 

lated... 7 

232 Acid treatment. Check ... 25 

238 Acid treatment. Check ... 25 

233 Inoculated. Limestone 

(10 pounds) 10 

239 Inoculated. Limestone 

(10 pounds) 4 

234 Limestone (10 pounds). 

Inoculated 6 

240 Limestone (10 pounds). 

Inoculated 

235 Limestone (10 pounds). 

Check 25 

241 Limestone (10 pounds). 

Check 25 



19 

21 

20 
18 




15 
21 

19 
25 






40 

38 


36 
44 



80.0 

76.0 
0.0 

72.0 

88.0 

0.0 



1919] CARNATION STEM EOT AND ITS CONTROL 593 

REPLANTING 

Experiments were carried on for two seasons to determine what 
percentage of the plants survived when replanted under ordinary 
greenhouse conditions. After a large number of plants had been 
taken out of the different sections in a diseased condition, they were 
replaced by new plants. As can be seen from Table 8, 68 to 100 per- 
cent of the replants were killed by stem rot. An average of 92 per- 
cent for all sections was lost. From these results we can conclude 
that the mortality of the replants is extremely high and in a few 
cases only will they survive thru a growing season. 

TEMPERATURE 

Cultures of Rhizoctonia in the laboratory have shown that the 
fungus grows best at a relatively high temperature. The optimum 
temperature for the growth of the fungus is from 86 to 88 degrees 
Fahrenheit. This is much higher than the optimum temperature for 
the growth of the carnation plant. Carnations in the greenhouse 
are grown, when possible, at 50 to 53 degrees F. at night and 60 
to 62 degrees F. during the day. Altho the stem-rot fungus will 
grow at the latter temperatures, its growth is slow. These facts 
indicate that there may be a temperature relation between the growth 
of the parasite and host infection, and that possibly temperature 
is the controlling factor in infection. Carnation growers probably 
are aware of the fact that losses due to stem rot are greater at 
certain periods of the year than at others. The following data, 
collected during a period of five years, show that this is true. The 
data also tend to confirm the existence of a more or less definite rela- 
tion between temperature and loss by stem rot. 

In Table 9 is given the data of the benching of carnation plants 
for five years and the subsequent losses of plants by months. 

For two seasons the plants were benched during September; the 
following three seasons they were benched in August. From the 
data presented it is seen that the greater losses occur during the 
month following that of benching. When benching was done in Sep- 
tember, no loss occurred during that month, but the greater loss 
occurred during October. When benching was done in August, the 
greater loss occurred in September, and the total loss was much larger 
than among the plantings benched in September. It also is seen from 
the data that loss gradually decreases from the first month after 
benching to the beginning of the warmer months of the following 
season. In Table 8, also, the monthly loss is tabulated, with the same 
results. During August, September, and October, in the state of 
Illinois, the outdoor temperature is high and the temperature in the 



94 



BULLETIN No. 223 



[September, 






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1919} 



CARNATION STEM EOT AND ITS CONTROL 



595 



greenhouses correspondingly high. Beginning with November, lower 
temperatures prevail out of doors and the temperature indoors is 
correspondingly lower. With these lower temperatures there results 
a gradual falling off in plant losses due to stem rot. 

During the season 1913-14 a number of sections containing carna- 
tions were reserved in the greenhouse and one section inoculated 
at the first of each month, with Khizoctonia. Each section contained 
twenty plants, sixteen of which were inoculated by placing infected 
bean plugs at the base of the stem. The remaining four plants 
served as checks. 



TABLE 10. EFFECT OF SEASONAL TEMPERATURES ON THE DEATH RATE OF 
CARNATION PLANTS FROM STEM ROT IN THE GREENHOUSE: 1913-14 



Sec- 
tion 


Date of 
inoculation 


Experiment 
discontinued 


Inoculated plants 


Check plants 


Healthy 


Diseased 


Healthy 


Diseased 


143 


Sept. 1, 1913 


Oct. 1, 1913 


1 


15 


4 





140 


Oct. 1, 1913 


Nov. 1, 1913 


3 


13 


4 





139 


Nov. 1, 1913 


Jan. 1, 1914 


10 


6 


4 





138 


Dec. 1, 1913 


Feb. 1, 1914 


8 


8 


4 





137 


Jan. 1, 1914 


Mar. 1, 1914 


14 


2 


4 





134 


Feb. 1, 1914 


Apr. 1, 1914 


3 


13 1 


4 





133 


Mar. 1, 1914 


May 1, 1914 


12 


4 


4 





132 


Apr. 1, 1914 


June 1, 1914 


9 


7 


4 





131 


May 1, 1914 


July 1, 1914 





16 


4 





130 


June 1, 1914 


July 1, 1914 


2 


14 


4 





128 


July 1, 1914 


July 23, 1914 


6 


10 


4 






*Ten plants found infected April 1; only three plants died during the 
months of February and March. 

As can be seen from Table 10, the death rate of the plants inocu- 
lated the first two months was high. This rate diminished markedly 
thru the colder months, increasing in the spring, until in May it had 
again reached a maximum. During the remaining two months this 
same condition prevailed, showing very noticeably the influence pf 
temperature on mortality. 

SOIL MOISTURE 

In 1913 the soil in eight sections was inoculated with a soil culture 
of Rhizoctonia and each section planted to twenty-five plants (variety 
Gloriosa). The plants were grown at the usual temperatures of 
carnations in greenhouses (53-55 degrees F. by night and 65-70 de- 
grees F. by day). In order to determine the influence of soil moisture 
on death rate due to stem rot, the various sections were given different 
applications of water. The soil of two sections (Nos. 135 and 136) 
was kept uniformly moist, the soil moisture being approximately that 
which carnation growers attempt to maintain for the growth of com- 
mercial plants. The soil of three sections (Nos. 126, 144, and 185) 
was kept almost saturated by applying water frequently. The soil 



596 



BULLETIN No. 223 



[September, 



of the three remaining sections (Nos. 127, 145, and 166) was kept 
dry. (The term dry does not imply that no water was applied, but 
it means that less water was given the plants than growers ordinarily 
use in growing carnations.) As nearly as it was 'possible to do so, 
the soil moisture of each section was kept uniform and constant thru- 
out the season. 

Eecords of losses of each section are tabulated in Table 11. The 
average losses for the saturated, the "normal," and the dry sections 
were 36, 22, and 21 percent respectively. These figures seem to 
indicate that a high degree of soil moisture, at the temperatures of 
a carnation house, is favorable to infection by stem rot. 

TABLE 11. EFFECT OF SOIL MOISTURE ON VIRULENCE OF STEM ROT IN THE 
GREENHOUSE: 1913-14 



Sec- 
tion 


Saturated 


Sec- 
tion 


Normal 


Sec- 
tion 


Low 


No. of 
plants 
dead 


Percent 
loss 


No. of 
plants 
dead 


Percent 
loss 


No. of 
plants 
dead 


Percent 
loss 


126 
144 
185 


5 
9 
13 


20 
36 
52 


135 
136 


7 
4 


28 
16 


127 

145 
166 


2 
10 
3 


8 
40 
14 



In 1914 the experiment was repeated, with some modifications. 
Instead of growing the plants at the usual carnation temperatures, a 
high soil temperature was maintained in the benches. The under- 
lying reason for this procedure was to determine whether the same 
percentages of loss from stem rot would occur thruout the season 
and whether the moisture relation might be of value in an effective 
control of stem rot. If high temperature that is, a temperature 
above that best suited for carnation growing is instrumental in pro- 
voking infection (as the data of Tables 8, 9, and 10 would lead one 
to believe), then possibly the soil-moisture factor might be success- 
fully employed to counteract the influence of high temperatures. High 
temperatures of course are often unavoidable, especially at seasons 
of the year when the outdoor temperature is high. 

Four twenty-foot benches were divided each into four five-foot 
sections and each section planted to twenty-five plants (variety 
Gloriosa). The soil of the different sections was inoculated at dif- 
ferent times of the year, as shown in Table 12. During the early 
part of the season the air temperature was high, so that no effort 
was made to control the soil temperature in Bench 1. Later the 
soil temperature was controlled by inclosing, by means of boards, the 
area under three benches (Nos. 2, 3, and 4). Previously an extra 
steam pipe, also, was added to the regular number of heating pipes, 
and by means of this increased radiating surface the temperature of 
the soil in the benches could be raised several degrees over that of the 



CARNATION STEM EOT AND ITS CONTROL 



597 



temperature of the house. No soil thermograph being available, fre- 
quent readings were made from a soil thermometer set from three to 
four inches into the soil. Thruout the winter the soil temperature 
of Benches 2, 3, and 4 was several degrees higher than was the air 
temperature of the house. 

The soil of Section 1 of each bench was kept dry, being watered 
thoroly only when absolutely needed. Section 2 received a "normal" 
supply of water; Section 3, above normal; and Section 4 was con- 
tinually saturated. Table 12 gives the results of the experiment. 

TABLE 12. EFFECT OF HIGH TEMPERATURE AND SOIL MOISTURE ON THE 

DEATH RATE OF CARNATION PLANTS FROM STEM ROT IN 

THE GREENHOUSE: 1914-15 



Bench 


Dates of 
inoculation and 
of ending of 
experiment 


Section 4 
Saturated 


Section 3 
Above 
normal 


Section 2 
Normal 


Section 1 
Low 


No. of 
plants 
dead 


Per- 
cent 
loss 


No. of 
plants 
dead 


Per- 
cent 
loss 


No. of 
plants 
dead 


Per- 
cent 
loss 


No. of 
plants 
dead 


Per- 
cent 
loss 


1 

2 
3 
4 


Aug. 7-Nov. 1... 
Dec. 1-Feb. 1... 
Feb. 1-Apr. 1 ... 
May 1-July 1 ... 


15 

7 
16 
21 


60 
28 
64 

84 


12 

7 
15 
19 


48 
28 
60 
76 


6 
5 
12 
13 


24 
20 
48 
52 


14 
12 
19 
14 


56 
48 
76 
56 



The data again show that the percentage of loss was higher in 
the sections in which the soil moisture was high. However, the per- 
centage of loss was equally high in the sections with the dry soil. In 
the latter case the plants suffered severely from lack of water, as 
was quite evident by their appearance, and this weak condition of 
the plants no doubt accounts for the high percentage of infection 
(Fig. 4). The important fact brought out by the data is that in all 
cases the percentage of loss from stem rot was high in all sections 
thruout the year, showing quite conclusively that soil temperature 
is the limiting condition in the control of stem rot. 

The data also show in a striking way the double relation of mois- 
ture and temperature to infection. A high soil moisture is favorable 
to infection ; a high temperature also is favorable to infection. Under 
conditions of both a high temperature and a high percentage of soil 
moisture, the loss exceeds that of either alone. In other words, soil 
moisture and soil temperature each have an important bearing on 
the loss of carnations by stem rot. With either condition prevailing 
or both conditions present, we have conditions very favorable for 
the fungus infection. 



BULLETIN No. 223 



[September, 




1919] CARNATION STEM EOT AND ITS CONTROL 599 

ATTEMPTS TO CONTKOL STEM ROT IN THE GREENHOUSE 
BY DISINFECTION AND STERILIZATION OF THE SOIL 

In all the experiments discussed in the foregoing pages and under 
this heading the treatment of the soil in the house was the same as 
described in Bulletin 176 of this station. Unless otherwise stated in 
the experiment, all the sections were given the same treatment. 

All infected sections were inoculated with a two-week-old soil 
culture of Rhizoctonia figured and described in Bulletin 189. For 
the five-foot sections a one-pint culture jar was used, and for the ten- 
foot sections, a one-quart culture. 

DISINFECTION OF THE SOIL 

Various soil disinfectants have been recommended and employed 
in the treatment of soil in order either to eliminate the parasite or 
to so weaken its activities that infection is greatly reduced. Hartley 1 
recommends the use of sulfuric acid in soils to prevent damping-off 
of pine seedlings in Western nurseries, by Rhizoctonia and other 
fungi. In his experimental work he found an application of the acid 
in aqueous solution, made at the rate of three-sixteenths fluid ounce 
per square foot of soil, to be effective. Aqueous solutions of formalin 
have been recommended and are frequently used to rid soils and plant 
structures, such as tubers and seeds, of destructive fungi. It is a 
common practice of carnation growers in replacing dead plants to 
mix with the soil of the replant a small quantity of lime to ward 
off, presumably, the attack of the fungus. Various other so-called 
disinfectants have been employed from time to time and various rec- 
ommendations may be found in the literature. The results of different 
investigations often are contradictory, probably due to the difference 
in soils employed and in the control of conditions during the investi- 
gation. 2 

Sulfuric Acid and Lime. Under the heading of acidity and alka- 
linity of the soil (page 588) are given the results of the use of sulfuric 
acid and lime in a carnation soil. As a control method it failed abso- 
lutely in the three seasons it was carried on. As can be seen from 
Tables 6 and 7, a loss of 84 percent occurred in the infected sections 
treated with sulfuric acid, and 85 percent of the plants were lost in 
the corresponding lime sections during the two seasons 1913-14 and 
1914-15. 

Bordeaux and Copper Sulfate. The soil in three sixteen-foot sec- 
tions was inoculated with Rhizoctonia, watered, and allowed to stand 



hartley, Carl. The Use of Fungicides to Prevent Damping-Off. Phytopath. 
2, 99. 1912. 

2 Another important factor, not yet thoroly understood, is the effect of 
the disinfectant on the life and activity of the soil organisms. 



600 



BULLETIN No. 223 



[September, 



TABLE 13. RESULTS OF BORDEAUX AND COPPER-SULFATE TREATMENTS ON 
CONTROL OF STEM ROT IN THE GREENHOUSE: 1912-13 



Sec- 
tion 


Treatment 


Number of 
plants 


Number 
dead 


Percentage 
loss 


106 


Copper sulf ate 


32 


13 


40 6 


107 


Check 


32 


3 


9 4 


108 


Bordeaux 


32 


11 


34.4 



for several days. One section then was drenched with Bordeaux 
(4-4-50), applied at the rate of two gallons to ten square feet. Each 
section was planted to thirty-two Beacon plants. At the end of the 
season no favorable results were evident. Stem rot appeared in each 
section; the data (Table 13) show even a greater percentage of loss 
in the treated section than in the untreated section. Whether the 
copper had an unfavorable influence on the carnation plants was not 
determined. 

Formalin. Formalin as a soil disinfectant for stem rot was tested 
during three successive seasons. In August, 1912, two ten-foot sec- 
tions were inoculated with soil cultures, watered, and allowed to stand 
for several days. To one section a formalin solution (1-200) was 
applied at the rate of one gallon per square foot, with a sprinkler. 



TABLE 14. RESULTS OF FORMALIN TREATMENT IN THE CONTROL 
CARNATION STEM ROT IN THE GREENHOUSE: 1913-14 



OF 







Number 


of plants 






TV-,*,,! 


Sec- 
tion 


Treatment 


Gloriosa 


White 
Enchant- 


ber 
dead 


local 
number 
dead 


iotal 
percent 
loss 








ress 








144 


Inoculated. Formalin .... 


25 




3 












25 


12 


15 




151 


Inoculated. Formalin 


25 

















25 


9 


9 


24 


147 


Formalin. Inoculated 


25 

















25 










152 


Formalin. Inoculated. . . . 


25 




5 












25 


25 


30 


30 


148 


Inoculated 


25 

















25 


1 


1 




153 


Inoculated 


25 




6 












25 


23 


29 


30 


149 


Formalin 


25 

















25 










154 


Formalin 


25 

















25 











150 


Check: no treatment 


25 

















25 


12 


12 




155 


Check : no treatment 


25 

















25 








12 



1919] 



CARNATION STEM EOT AND ITS CONTROL 



601 



The soil would not take up all the solution at one time, so three appli- 
cations had to be made during the day. The bench was then covered 
with a tarpaulin for a few days to prevent a rapid loss of the fumes. 
The soil was allowed to dry. On August 17 both sections were planted 
to fifty plants (variety Beacon). During the season, one plant died 
in the treated section and two in the check. No conclusions can be 
drawn from this experiment because of the low percentage of loss 
occurring in both sections. 

In 1913 ten ten-foot sections were prepared for the formalin ex- 
periment, and divided into five treatments of two sections each. The 
first set was inoculated with soil cultures of Rhizoctonia, watered, and 
allowed to stand several days. A solution of formalin (1-120) was 
then applied at the rate of one gallon per square foot. In the second 
set the soil was treated with a like solution of formalin, allowed to 
dry, and then inoculated. The third set of sections was inoculated 
and allowed to stand. The soil in the fourth set was treated with 
formalin as in the first set, while the last two sections were given no 
treatment and served as checks. 

Each section was planted to twenty-five Gloriosa and twenty-five 
White Enchantress, on August 25, 1913. 

TABLE 15. RESULTS OP FORMALIN TREATMENT IN THE CONTROL OP 
CARNATION STEM ROT IN THE GREENHOUSE: 1914-15 







Number 


of plants 








Sec- 
tion 


Treatment 


Gloriosa 


White 
Enchant- 
ress 


Num- 
ber 
dead 


lotal 
number 
dead 


lotal 
percent 
loss 


202 
207 


Inoculated. Formalin.... 
Inoculated. Formalin 


25 
25 


25 
25 


11 
9 

13 
20 


20 
33 


53 


203 
208 


Formalin. Inoculated. . . . 
Formalin. Inoculated... 


25 

25 


25 
25 


17 
23 

19 
25 


40 
44 


S4 


204 


Inoculated 


25 




17 






209 


Inoculated 


25 


25 


18 
17 


35 










25 


25 


42 


77 


205 


Formalin 


25 











210 


Formalin 


25 


25 

















25 











206 


Check : no treatment 


25 











211 


Check : no treatment . . . 


25 


25 

















25 












602 BULLETIN No. 223 [September, 

This same experiment was repeated in 1914, except that formalin 
(1-50) was applied at the rate of one-half gallon per square foot, as 
had been recommended by Johnson 1 for controlling damping-off. 

The results presented in Tables 14 and 15 show that the use of 
formalin as a soil disinfectant for two years was but a partial suc- 
cess. The loss, even after the application of the formalin, varied 
from 24 to 53 percent (see Fig. 5). In the sections in which the soil 
was not artificially inoculated prior to the application of the formalin, 
no losses are recorded. This may be due, however, to the possibility 
that the organism was not present in the soil, for in the check sections 
of the last series no stem rot occurred. 

STEAM STERILIZATION 

A sterilizing box measuring 4 feet by 16 feet by 20 inches was 
constructed of two-inch boards. It was divided into two equal com- - 
partments for the simultaneous sterilization of soil artifically inocu- 
lated and of soil not inoculated. Another sterilizing box, 4 feet by 
8 feet by 10 inches, was built for the purpose of sterilizing manure. 

The large box was fitted with four perforated steam pipes, run- 
ning lengthwise, 12 inches apart and about 6 inches from the bottom. 
The perforations in the pipes were % 6 inch in diameter and 12 inches 
apart, alternating in position on two adjacent pipes. By means of 
T's and L's the pipes in the box were connected, thru a valve, with 
a pipe leading directly to the boiler. The latter contained, at a point 
beyond this connection, another valve by means of which all water 
and wet steam could be released prior to forcing the steam into the 
soil box. A lid of boards completed the sterilizing apparatus. 

The smaller box contained three steam pipes connected in a simi- 
lar way with the pipe leading to the boiler. After filling the compart- 
ment with soil, dry steam was forced thru the pipes at forty pounds 
pressure for one hour. 

In case the soil was to be inoculated, the amount necessary to fill 
a section of bench was calculated, a soil culture of Ehizoctonia added, 
the whole thoroly mixed, watered, covered, and allowed to stand sev- 
eral days before sterilization. 

After the sterilization was complete, the lid was removed and the 
soil allowed to cool. It was then taken into the greenhouse in disin- 
fected wheelbarrows. 

The experiment was begun in 1912 by using two sections of bench, 
each ten feet long. The soil of one section was inoculated with the 
fungus, and after several days was steam sterilized; the soil of the 
second section was inoculated but not sterilized. Each section was 

'Johnson, J. The Control of Damping-off Disease in Plant Beds. Wis 
Agr. Exp. Sta. Ees. Bui. 31, 29-61. 1914. 



1919} 



CARNATION STEM EOT AND ITS CONTROL 



603 




604 



BULLETIN No. 223 



[September, 



TABLE 16. RESULTS OF STEAM STERILIZATION IN THE CONTROL OP STEM 
ROT IN THE GREENHOUSE: 1912-13 



Sec- 
tion 


Treatment 


Number of 
plants 


Number 
dead 


Percentage 
loss 


101 


Inoculated. Sterilized 


52 








102 


Inoculated. Check 


52 


38 


73 



planted (August 9) to fifty-two plants of Beacon carnations. The 
losses are tabulated in Table 16. No loss of plants occurred in the 
sterilized soil; in the unsterilized soil 73 percent of the plants were 
lost by the disease. 

During the season of 1913-14 and 1914-15 the experiment was 
repeated on a larger scale. Five ten-foot sections were used, each in 
duplicate. The soil of the first set was inoculated and sterilized; 
that of the second set was sterilized and then inoculated; the soil 
of the third set was inoculated only ; that of the fourth set was steril- 
ized only. The soil of the fifth set received no treatment and served 
as a general check. 

The results are brought together in Tables 17 and 18. In all cases 
where steam sterilization was used no loss of plants occurred. In all 



TABLE 17. RESULTS OF STEAM STERILIZATION IN THE CONTROL OF 
ROT IN THE GREENHOUSE: 1913-14 



STEM 







Number 


of plants 




TYvtol 


TY>nl 


Sec- 
tion 


Treatment 


Gloriosa 


White 
Enchant- 
ress 


ber 
dead 


number 
dead 


percent 
loss 


156 
161 


Inoculated. Sterilized 
Inoculated. Sterilized 


25 
25 


25 
25 
















157 
162 


Sterilized. Inoculated 
Sterilized. Inoculated 


25 
25 


25 
25 


21 
25 

1 

2 


46 
3 


49 


158 


Inoculated 


25 




9 






163 


Inoculated 


25 


25 


23 

8 


32 










25 


25 


33 


65 


159 


Sterilized 


25 











164 


Sterilized 


25 


25 

















25 











160 


Check: no treatment . . 


25 











165 


Check: no treatment 


25 


25 

















25 












1919] 



CARNATION STEM ROT AND ITS CONTROL 



605 



TABLE 18. ^RESULTS OF STEAM STERILIZATION IN THE CONTROL OF STEM 
ROT IN THE GREENHOUSE: 1914-15 







Number 


of plants 








Sec- 
tion 


Treatment 


Gloriosa 


White 
Enchant- 
tress 


her 
dead 


number 
dead 


percent 
loss 


216 
221 


Inoculated. Sterilized 
Inoculated. Sterilized 


25 
25 


25 
25 
















217 
222 


Sterilized. Inoculated 
Sterilized. Inoculated 


25 
25 


25 
25 


1 

19 

10 
24 


20 
34 


54 


218 


Inoculated 


25 




18 






223 


Inoculated 


25 


25 


21 

22 


39 










25 


25 


47 


86 


219 


Sterilized 


25 











224 


Sterilized 


25 


25 

















25 











220 


Check: no treatment 


25 











225 


Check : no treatment 


25 


25 

















25 












sections in which the fungus was introduced and not sterilized, the 
losses ranged from 49 to 86 percent (see Fig. 5). Why no losses 
occurred in the untreated sections is difficult to explain, unless it 
may be inferred that the fungus was not present in the soil. 

Records were kept of the production of flowers by the plants in 
the various sections. These records are given in Tables 19 and 20. 
In no case was production affected by the soil sterilization process. 

TABLE 19. EFFECT OF STEAM-STERILIZED SOIL ON PRODUCTION AND QUALITY 
OF CARNATION FLOWERS: 1913-14 



Sections 


Treatment 


No. of 
flowers 


Perfect 


Size 


Stem 
length 


Firsts 



Gloriosa 



156, 161 


Sterilized 


No. 
584 


No. 
562 


percent 
98.2 


inches 
2.79 


inches 
17.81 


No. 
470 


percent 
80.5 


160, 165 


Check 


579 


565 


97.5 


2.76 


17.09 


259 


44.7 


159, 164 


Sterilized 


568 


552 


97.2 


2.76 


17.07 


396 


70.0 



White Enchantress 



156, 161 


Sterilized. . . . 


863 


706 


81.2 


3.11 


14.74 


758 


87.8 


160, 165 


Check 


773 


713 


92.2 


3.12 


14.76 


643 


83.8 


158, 164 


Sterilized 


819 


660 


81.8 


3.11 


14.64 


637 


77.7 



606 



BULLETIN No. 223 



[September, 



TABLE 20.- 



-EFPECT OF STEAM-STERILIZED SOIL ON PRODUCTION AND QUALITY 
OF CARNATION FLOWERS: 1914-15 



Sections 


Treatment 


No. of 
flowers 


Perfect 


Size 


Stem 
leflgth 


Firsts 



Gloriosa 



216, 221 


Sterilized 


No. 
591 


No. 
577 


percent 
97.6 


inches 
2.87 


inches 
20.53 


No. 
508 


percent 
89 3 


220, 225 


Check 


570 


533 


93.5 


2.83 


19.73 


479 


84.0 


219, 224 


Sterilized 


579 


563 


97.2 


2.86 


19.12 


475 


82.0 



White Enchantress 



216, 221 


Sterilized 


721 


679 


94.1 


3.18 


18.83 


701 


97.2 


220, 225 


Check 


705 


674 


95.6 


3.16 


18.69 


674 


95 7 


219, 224 


Sterilized 


762 


689 


90.4 


3.09 


19.00 


737 


96.7 



CONCLUSIONS AND RECOMMENDATIONS 

From the data and experimental evidence presented in this bulletin 
it seems clear that the control of stem rot of carnations lies along 
the line of careful control of growing conditions of the carnation 
plant and in the use of a clean ^oil. The disease is a soil disease. 
The organism lives in the soil, under ordinary conditions as a 
saprophyte, but under more favorable conditions attacking the carna- 
tion plant and causing its destruction. The conditions influencing its 
spread and development are high soil temperature and soil moisture. 

Soil Disinfectants of Little Value. The results of these experi- 
ments indicate that the usual soil disinfectants, such as sulfuric acid, 
lime, Bordeaux, copper sulfate, and formalin, applied to the soil have 
but little effect on the fungus and that they are consequently of little 
value as a means of controlling the disease. No chemical solution was 
found which, when applied to the soil in quantities not harmful to 
the plant, eradicated the fungus. The fungus is very resistant in soil 
to weak solutions of acids and alkalies. It is also resistant to low tem- 
peratures and drying. Evidence is presented that it lives in soils for 
years, resisting all the rigorous conditions of a cold winter and a 
hot summer. 

Steam Sterilization Effective. In order completely to eradicate 
the fungus from the soil, steam sterilization alone seems to be effective. 
Dry steam forced thru the soil at forty pounds pressure for one hour 
will destroy the fungus. There is no indication that such steriliza- 
tion of soil is accompanied by evil effects on the growth or the pro- 
duction of carnation plants. Sterilized soil grows equally good 
carnation plants as unsterilized soil. However, aside from the labor 
and expense involved in sterilization, unless the plants brought in 
from the field- are free from the disease organism the disease may 
again be introduced into the soil of the benches. There is of course 



1919] CARNATION STEM EOT AND ITS CONTROL 607 

but little assurance that the fungus is not present in the field. In 
order to prevent the introduction of the disease from the field into the 
benches, only healthy and uninjured plants should be used. Every 
plant should be carefully examined at the crown for evidences of the 
disease and any plant showing symptoms should be discarded. 

Importance of Low Temperature and Minimum of Moisture. 
The first month the plant is in the bench is the most critical point in 
the life of the plant, especially if the transplanting is done early. The 
temperature of the greenhouse is high at this time, and, still more 
important, owing to the large amount and the frequent use of water 
concomitant with transplanting, the humidity of both soil and air 
is high. Experiments have shown that high temperature and high 
water content of soil, especially when existing simultaneously, offer 
a most favorable environment to the fungus. High temperatures in 
the cutting bench and in the carnation house give Rhizoctonia a two- 
fold advantage; they lower the vitality of the cuttings and plants 
and give the fungus optimum conditions under which to develop. In 
other words, when normal temperature for the best development of 
the plant is furnished, no stem rot occurs ; while if high temperatures 
are maintained, the vitality of the plant is lowered, thus making it 
more susceptible to stem rot. At the same time, high temperatures 
favor the growth of the fungus, increasing its virulence. A careful 
watch, therefore, of the growing conditions of the plants is necessary 
at this time. The temperature should be kept as low as possible and 
no more water applied to the soil than is absolutely necessary for 
a healthy growth of the plant. 

Seedlings and Cuttings. These statements apply also to the grow- 
ing of seedlings and cuttings. Steam sterilization of soil and sand 
is recommended whenever it is possible. The cutting bench offers 
a most favorable environment for the growth of the fungus if it is 
present in the sand. A relatively high temperature and high per- 
centage of moisture of the sand, as well as the high humidity of the 
air resulting from artificial shading, are characteristic of the cutting 
bench. Under such conditions it is extremely difficult to control 
damping-off if it is present in the sand. It is therefore recommended 
that the sand be sterilized with steam and careful attention given 
later to the moisture and temperature conditions. A relatively high 
temperature of soil together with a high percentage of moisture is 
conducive to infection. It is important, therefore, that the tempera- 
ture be "kept as low as possible for a good healthy growth of the 
carnation plant. This temperature, since it is lower than that of 
the optimum temperature of the fungus, will prove an important 
factor iu the control of infection. 



AUTHOR INDEX 



(500 



AUTHOR INDEX 



Bull, Sleeter, Grindley, H. S., 
Mumford, H. W., and Em- 
niott, A. D. Fertilizing Con- 
stituents Excreted by Two- 
year-old Steers '. . . . 127-162 

Bm-lison, W. L., and Stark, E. W. 

Spring Wheat for Illinois. 313-320 

Crandall, Charles S. Apple-Bud 
Selection : Apple Seedlings 
from Selected Trees 179-264 

Kmmett, A. D., Grindley, H. S., 
Mumford, H. W., and Bull, 
Sleeter. Fertilizing Constit- 
uents Excreted by Two-year- , 
old Steers .".127-162 

Fahrnkopf, H. F. T., Hopkins, 
Cyril G., Garrett, F. W., 
and Whitchurch, J. E. Illi- 
nois Crop Yields from Ex- 
periment Fields 397-504 

Garrett, F. W., Hopkins, Cyril G., 
Whitchureh, J. E., and 
Fahrnkopf, H. F. T. Illinois 
Crop Yields from Experi- 
ment Fields 397-504 

Grindley, H. S., Mumford, H. W., 
Emmett, A. D., and Bull, 
Sleeter. Fertilizing Constit- 
uents Excreted by Two-year- 
old Steers '.127-162 

Grindley, H. S., and Busk, H. P. 
Field Investigations of For- 
age Poisoning in Cattle and 
Horses 161-176 

Gunderson, A. J. Field Experi- 
ments in Spraying Apple 
Orchards for the Control of 
Apple Blotch 549-576 

Gunderson, A. J. The Pruning 
of Winter-Injured Peach 
Trees 381-394 

Hopkins, Cyril G., Garrett, F. W., 
Whitchurch, J. E., and 
Fahrnkopf, H. F. T. Illinois 
Crop Yields from Soil Ex- 
periment Fields 397-504 



PAGE 

Mosier, J. G. Climate of Illi- 
nois 1-126 

Mumford, H. W., Grindley, H. S., 
Emmett, A. D., anil Bull, 
Sleeter. Fertilizing Constitu- 
ents Excreted by Two-year- 
old Steers 127-162 

Pearson, F. A. The Cost of Milk 
Production Computed on the 
Year Basis 341-364 

Peltier, George L. Carnation 

Stem Rot and its Control. 577-608 

Peltier, George L. Snapdragon 

Rust 533-548 

Rusk, H. P., and Grindley, H. S. 
Field Investigations of For- 
age Poisoning in Cattle and 
Horses 161-176 

Stark, R. W., and Burlison, W. L. 

Spring Wheat for Illinois . 313-320 

Stevens, Frank Lincoln. An Ap- 
ple Canker Due to Cyto- 
spora '365-380 

Stevens, Frank Lincoln. Two Illi- 
nois Rhubarb Diseases. . .297-312 

Stevens, Frank Lincoln, and True, 
Esther Young. Black Spot 
of Onion Sets 505-532 

Stewart, Robert, and Wyatt, F. 
A. Limestone Action on Acid 
Soils 265-296 

True, Esther Young, and Stevens, 
Frank Lincoln. Black Spot 
of Onion Sets 505-532 

Whitchurch, J. E., Hopkins, Cyril 
G., Garrett, F. W., and 
Fahrnkopf, H. F. T. Illi- 
nois Crop Yields from Ex- 
periment Fields 397-504 

Wyatt, F. A., and Stewart, 
Robert. Limestone Action on 
Acid Soils 265-296 

Yapp, W. W. A Study of the 
Relative Reliability of Offi- 
cial Tests of Dairy Cows. 321-340 



610 



VOLUME 15 



INDEX 



(The headings in capitals are subjects of entire bulletins) 



PAGE 

Acidity of soil, influence on car- 
nation stem rot 588-92 

Aledo experiment field, Crop 

yields in soil experiments. 405, 407 
Alfalfa, germination at various 

temperatures 25 

Alkalinity of soil, effect on car- 
nation stem rot 588-92 

Anthracnose, on onion sets 507 

Ehubarb 299-308 

Anticyclones, Weather changes 

produced by 5, 9 

Antioch experiment field, Crop 

yields in soil experiments. 406, 407 

Antirrhinum ma jus 535, 540,548 

Apple blotch 

Recommendations for control 

of 575 

Spraying for control of 549-75 

Weather conditions affecting. . 553 
Apple-bud selection 

Comparative value of buds 
from different locations on 

shoot 232-50 

from different Ideations on 

tree 202-31 

Comparative value of robust 

and slender scions 250-52 

Conclusions 263-64 

Effect of vigor of stock on 

growth 252 

Influence of care in grafting. 252-53 

Test of size 183-202 

Varietal and individual differ- 
ences 253-54 

APPLE-BUD SELECTION: AP- 
PLE SEEDLINGS FROM 
SELECTED TREES .... 179-264 
APPLE CANKER DUE TO 

CYTOSPORA, AN 365-79 

Bibliography 377-79 

Description 367-68 

Fungus 368-72 

APPLE ORCHARDS, FIELD 
EXPERIMENTS IN 
SPRAYING, FOR CON- 
TROL OF APPLE 

BLOTCH 549-75 

Apple seedlings, tests with, from 

selected trees 254-64 

Black spot of onion sets 505-32 

See also Onion sets 



PAGE 



Bloomingtou experiment field, 
Crop yields in soil experi- 
ments 408,410 

Blotch, Apple, see Apple blotch 
Calves, Tests to determine feeds 
responsible for unthriftiness 

of 165-67 

Carlinville experiment field, crop 
yields in soil experi- 
ments 409,410 

CARNATION STEM ROT AND 

ITS CONTROL 577-607 

Carnations 

Branch rot 583 

Stem rot 

Conditions influencing growth 
of parasite and host. . . .58497 

Control of 599-606 

Conclusions and recommen- 
dations 6'06-07 

Fungus 585-86 

Carthage experiment field, Crop 

yields in soil experiments. 411, 413 
Cattle, Feeding tests for forage 

poisoning of 163-69 

See also Dairy cows, Steers 
Chicago, Cost of milk production 

for 344-64 

Clayton experiment field, Crop 

yields in soil experiments. 412, 413 
Cleistothecopsis circinans .... 507, 530 

CLIMATE OF ILLINOIS 1-125 

Clover, Red, germination at var- 
ious temperatures 25 

Colletotrichum erumpens .... 299-308 
Colletotrichum, Falcate-spored 

forms of 307-08 

Corn 

Days required for germination 

at various temperatures 25 

Effect of rainfall on yield 28-30 

Temperature for growth 27 

Corn silage, see Silage 

Corticium vagum 579 

Cows, see Cattle, Dairy cows 
Cutler experiment field, Crop 

yields in soil experiments . 41416 
Cyclones, Weather changes pro- 
duced by 5, 9 

Cytosporas 

Bibliography 377-79 

on Rosaceous hosts 374-75 



INDEX 



611 



PAGE 

DA1HY COWS, A STUDY OF 
THE RELATIVE RELIA- 
BILITY OF OFFICIAL 

TESTS OF 321-39 

Dairy cows 
Official tests 

Comparison of seven-day test 
and seven-day test eight 
mouths after calving. . .334-36 
Comparison of seven-and 

thirty-day tests 333-34 

Conclusions .'539 

Correlation between semioffi- 
cial and 337-38 

Explanation of 323-24 

Plan of investigation 325 

Records 324-2.1 

Relation of fat percentage 

to test period 327-28 

Variability in percentage of 

fat 330-32 

Semiofficial tests 

Accuracy 325-27 

Correlation between seven- 
day and 337-38 

Explanation of 324 

Relation of fat percentage 

to test period 328-30 

Variability in percentage of 

fat 332-33 

Used in tests 323 

Dairying, see Milk production 
DeKalb experiment field, Crop 

yields in soil experiments. .417-19 
Variety tests of spring 

wheat 318,319 

Dixon experiment field, Crop 

yields in soil experiments . 420-22 
Drainage, Effect upon loss of 

limestone from soil. . .272-73, 293 
Dubois experiment field, Crop 

yields in soil experiments . 423-24 
Dusting apple trees for control of 

apple blotch 551, 552 

Compared with liquid spray- 
ing 568, 569 

Edgewood experiment field, Lime- 
stone on 267-68 

Enficld experiment field, Crop 

yields in soil experiments.425, 427 
Experiment fields, see Soil experi- 
ment fields, names of particu- 
lar fields 
lowing experiment field, Crop 

yields in soil experiments . 426, 427 
Fairfield experiment field, Crop 
yields in soil experiments. . .428-30 

Fertilizers 402-03 

Commercial, Influence on car- 
nation stem rot of 587-88 



PACK 

Manures, Influence on carna- 
tion stem rot of 586-87 

Commercial value of. .15559, 354 

FERTILIZING CONSTITU- 
ENTS EXCRETED BY 
TWO-YEAR-OLD 
STEERS 127-62 

Flax, germination at various 

temperatures 25 

Flora, 111., Spraying experi- 
ments 553-75 

FORAGE POISONING IN CAT- 
TLE AND HORSES, FIELD 
INVESTIGATIONS OF.. 163-76 

Serum developed 171 

Serum treatment ..171-72,174,175 

Friend spray gun 571 

Frost, Time of, in Illinois 46-47 

Fungicides, Experiments for con- 
trol of snapdragon rust.. 541-44 
See also Sprays 

Galesburg experiment field, Crop 

yields in soil experiments. 43 1-34 

Grafting, Influence of care in. 252-53 

Grain system of farming on ex- 
periment fields 401-02 

Harristown, 111., Feeding test 

with suspected silage at. . .168-69 

Hartsburg experiment field, Crop 

yields in soil experiments. 435-36 

Holstein-Friesian dairy cattle 

used in tests 323 

Horses, Forage poisoning investi- 
gations 169-75 

Serum treatment . . .171-72, 174, 175 

Illinois, Climate 1-125 

ILLINOIS CROP YIELDS 
FROM SOIL EXPERI- 
MENT FIELDS 397-503 

Joliet experiment field, Crop 

yields in soil experiments. 437-38 

Kewanee experiment field, Crop 

yields in soil experiments. . . .439 

Lamoille experiment field, Crop 

yields in soil experiments. 440-41 

Lebanon experiment field, Crop 

yields in soil experiments . 442-44 

LIMESTONE ACTION ON 

ACID SOILS 265-96 

Results from Newton field . . 268-85 
Results from Odin field 286-95 

Limestone 

Comparative effect of light and 

heavy applications. . 286, 288, 291 
Comparative value of high-cal- 
cium and dolomitic 274-80 

Effect of degree of fineness. .280-82 
Effect of drainage upon loss 
of 272,293 



612 



YOM'MK 1") 



PAGE 

Effect on surface soil 270 

Influence on subsurface and 

subsoil . ...273-74,282-85,291-93 
Live-stock fanning on experiment 

fields 401 

McXabb experiment field, Crop 

yield in soil experiments. 445, 447 
Manure, see Fertilizers 
Motor iological summary, 111. Exp. 

Sta. (1889-1916) * 55-64 

MILK PRODUCTION, COST 

OF 341-64 

Bases of calculation 344-45 

Conclusions 364 

Cow as unit in determining. 357-64 

Expenses 360-64 

Xet cow cost 362-64 

Returns 362-63 

Dairy herd as unit in determin- 
ing 346-57 

Expenses 347-52 

Net herd cost 354-56 

Returns 353-54 

Farm as unit in determining. 345-46 

Source of data 345 

See also Dairy cows 
Minonk experiment field, Crop 

yields in soil experiments . 446, 447 

Mold on onion sets 507 

Morrow plots 401 

Crop yields in soil experi- 
ments 486-87 

Mt. Morris experiment field, Crop 

yields in soil experiments. 448-49 

Xeck rot of onion sets 507 

Xeoga, 111., Experiments with 

winter-injured peach trees. 386-87 
Xewton experiment field, Crop 

yields in soil experiments. .450-54 
Limestone experiment on ... .268-85 
Xitrogen excreted by steers. . .143-50 
Oats, germination at various tem- 
peratures 25 

Oblong experiment field, Crop 

yields in soil experiments . . . 455-56 
Odin experiment field, Crop yields 

in soil experiments 457-61 

Limestone experiments on ... 286-95 
Olney, 111., Experiment with win- 
ter-injured peach trees. . .387-93 
OXIOX SETS, BLACK SPOT 

OF 505-32 

Bibliography 532 

Causal fungus 509-11 

Control of 531-32 

Morphology 529 

Perithecium 511-12 

Taxonomic position of asciger- 

ous stage 529-30 

Type of disease 508-09 



PAGE 
Oquawka experiment field, Crop 

yields in soil experiment. .462-63 
Ottawa, 111., Forage poisoning in- 
vestigations at 169-76 

Pana experiment field, Crop yields 

in soil experiments 463-65 

PEACH TREES, THE PRUN- 
ING OF WINTER-IN- 
JURED 381-94 

Phosphorus excreted by steers . 150-55 

Phyllosticta straminella 308-312 

Poff Orchard, experiments at.. 387-93 
Pumpkin seed, germination at 

various temperatures 25 

Rainfall in Illinois 

10-22, 55-64, 65-119 

Raleigh experiment field, Crop 

yields in soil experiments . 466-67 
Rhizoctonia, Temperature best for 

growth of culture 593 

EhizoctontO' Solani 579 

Rhubarb Anthracnose 299-308 

Fungus 300-05 

RHUBARB DISEASES, TWO 

ILLINOIS 297-312 

Rhubarb leaf spot 308-12 

Fungus 310-12 

Rockford experiment field, Crop 

yields in soil experiments. 468-72 
Rosaceous twigs, Fungi on. . . .372-75 
Rye, germination at various tem- 
peratures 25 

Seedlings, Experiments with ap- 
ple 254-64 

Sidell experiment field, Crop 

yields in soil experiments . 473-74 
Silage, Feeding tests with sus- 
pected 163-69 

Smudge on onion sets 507 

SNAPDRAGON RUST 533-48 

Control ,. .541-47 

Fungus, Description of 538 

History and distribution. . . .535-36 
Host relationship and resis- 
tance 538-41 

In the field 547 

Prevention and control 541-47 

Recommendations 548 

Seed not carriers of 546-47 

Summary 548 

Symptoms 536-38 

Snowfall in Illinois 22-24 

Soil 

Disinfection of 599-602 

Limestone action on acid . . . 265-96 
Moisture affecting carnation 

stem rot 595-97 

Steam sterilization 602-06 

Temperature of. ... 42, 43, 44, 45, 46 



IXUEX 



613 



PAGE 

Soil experiment fields 

Illinois crop yields from. . .397-503 

List of 399,503 

Materials for soil treatment .402-0:? 

Rotations 401-02 

Systems of farming 401-02 

Sparta experiment field, Crop 

yields in soil experiments. .47576 
Spraying experiments 

for control of apple blotch . . 549-75 
Dusting and liquid spraying 

compared 568,569 

Incidental observations .... 

561,570-71,573,575 

Objects 551,561 

Recommendations 575 

Summary of results, 1916. . . .560 

1917 570 

1918 573 

for control of snapdragon 

rust 541-44 

Sprays for apple trees 

Arsenate of lead 551, 552 

with lime sulfur .568, 569 

Bordeaux 551 

Formula 552 

with lime sulfur, see Sprays 
for apple trees, Lime sulfur 
Copper sulfate . . .551, 552, 562, 563 

Lime sulfur 551,552,562,563 

arsenate of lead 562, 563 

copper sulfur mixture. . .562, 563 
Lime sulfur and Bordeaux 

Effect of interchanging. .559-60 

Relative values 

553-55, 563-65, 571-73 

Value of different applica- 
tions ..555-59,565-68,573,574 

Scalecide 551, 552, 562, 563 

Spring Valley experiment field, 
Crop yields in soil experi- 
ments 477 

Steam sterilization for control of 

carnation stem rot 602-06 

Steers, Experiments to determine 
fertilizing constituents ex- 
creted by two-year-old .... 127-62 

Conclusions 161-62 

Equipment and methods of ex- 
periment 131 

Feces 

Amount 133-34 

Chemical composition. . . . 135, 136 
Feeds 

Amount 132-33 

Composition 133 

Cost 157 

Rations 129-31 

Financial statement 155-59 

Nitrogen excreted 143-50 



PAGE 

Organic matter 

consumed 141, 143 

excreted 138-40, 141, 142 

Phosphorus excreted 150-55 

Summary 159-61 

Urine 

Amounts 136-37 

Collection and sampling.... 131 

Composition 136, 137-38 

'Stem rot, Carnation, sec Carnations 
Sunshine, average amount for Illi- 
nois 51 

Syringing, Effect on snapdragon 

rust of 545-46 

Temperature of Illinois 25-46 

Meteorological summary (1889- 

1916) 55-64 

Records 121-25 

Timothy, germination at various 

temperatures 25 

Toledo experiment field, Crop 

yields in soil experiments. 478-79 
Union Grove experiment field, 
Crop yields in soil experi- 
ments 480-82 

Unionville experiment field, Crop 

yields in soil experiments. 483-85 
Urbana, Variety tests of spring 

wheat 317,319 

Urbana experiment field, Crop 

yields in soil experiments. 486-97 

Valsas on fruits 376 

on Rosaceous hosts 372-73 

Vermicularia cirdnans. . .507, 529, 530 

V ermiculariose on onion sets 507 

Virginia experiment field, Crop . 
yields in soil experiments.498-500 

Volutella circinans .507-32 

Volutella, Falcate-spored forms 

of 307 

Voris Orchard, experiments at. 386-87 
Weather 

affecting apple blotch 553 

maps . . 6, 7 

See also Climate 
West Salem experiment field, Crop 

yields in soil experiments. . .501-02 
Wheat, germination at various 

temperatures 25 

WHEAT, SPRING, FOR ILLI- 
NOIS 313-20 

Culture 315 

Drills 316-17 

Time to sow 315-16 

Variety tests 317-18 

Yields and value 318-20 

Wind in Illinois 48-50,55-64 

Winter injury to peach trees. .383-94 



UNIVERSITY OF ILLINOIS-URBANA