43 ^ 
Journal of Agricultural Research voi. xxv, No. n 
Twenty-six days after planting, lesions were found on plants throughout 
the entire temperature range. Lesions which occurred at the extreme 
temperatures, 7 however, were very slight and in many cases consisted of 
little more than distinct browning of the outer tissues. The most severe 
destruction of the stem tissues occurred at the temperatures from 15 0 
to 24 0 C. As in Experiment 1, few plumules or growing points were 
destroyed. The control plants were again found free from lesions. 
Table IV .—Average of results from pea Experiments 1 and 2, including dry weight of 
plants grown as controls in Experiment 3 ( see figure 2) 
9.2 
12.0 
15.0 
18.1 
21.0 
24.0 
26.6 
29.0 
Average temperature. 
°C 
Average per¬ 
centage of 
plants injured. 
Average total 
intensity of 
injury. 
Average dry 
weight per 
plant. a 
44.6 
25. 8 
Gm. 
O. 062 
81.3 
75 - 0 
. 112 
83-3 
105.0 
.179 
89.5 
136. 6 
. 222 
70. O 
xoi. 0 
•243 
65.O 
71. 0 
•235 
45 - 0 
50.0 
. 226 
33 -o 
24.9 
. 2l6 
a The figures represent the average of 12 plants on which determinations were made. The exaggerated 
severity of the damage occurring in the sterilized soil (Experiment 3) justified the inclusion of data on 
growth of the host plant with the more normal results of Experiments 1 and 2. (See Experiment 3.) 
Experiment 3.—Greenhouse soil used in this experiment had been 
sterilized for two hours at 15 pounds' pressure and afterwards allowed to 
stand exposed to the atmosphere for three days before being placed in 
the cans. A small quantity of agar culture of Corticium vagum was then 
thoroughly mixed with the first 4 inches of earth in each can, and the 
seeds planted immediately thereafter at a depth of 2 inches. 
As in the previous experiments, one can at each temperature was used 
for the growth of plants in the inoculated soil and a similar series was 
used as a control. After 16 days' growth, the plants in both series were 
photographed (PI. 1). The control plants were then washed free from 
soil and the average dry weight of the plants determined for each tempera¬ 
ture (Table IV and fig. 2). Observations on the diseased plants taken at 
the time are recorded in Table V and are shown graphically in figure 3. 
Table V. —Effects of growing peas at various temperatures in steam-sterilized soil infested 
with Corticium vagum (Experiment 3) 
Temperature 
at depth of 
1 inch. 
Number 
of seeds 
planted. 
Number 
of plants 
grown in 
uninocu¬ 
lated soil. 
°C. 
[ 9-0 . 
20 
18 
12. 0. 
20 
20 
15*2 . 
20 
20 
18.0. 
20 
20 
20. 6. 
20 
l8 
24. 0. 
20 
19 
26. 4. 
20 
18 
28. 0. 
20 
20 
Plants grown in inoculated soil. 
Total 
num¬ 
ber. 
Number 
slightly 
injured. 
Number 
severely 
injured. 
Num¬ 
ber 
cut 
off. 
Number 
uninjured. 
Percent¬ 
age 
injured. 
Intensity 
of injury 
(points). 
15 
14 
I 
93-3 
138-3 
14 
1 
11 
2 
85-7 
114. 2 
14 
14 
100. 0 
150 . O 
TC 
15 
100. 0 
150.0 
13 
2 
8 
3 
77.0 
107. 6 
14 
I 
3 
3 
6 
57 -1 
64. 0 
l6 
2 
2 
3 
9 
43-7 
5 °* 7 
7 The number of plants showing slight injury justified separating the group slightly injured into two 
classes —very slightly injured and slightly injured . Each per cent in the former class was allowed one-half 
point, while the latter class was allowed its former rating of one point (see page 432, paragraph 2). 
