440 
Journal of Agricultural Research 
Vol. XXV, No. IX 
Lesions occurred on most of the plants throughout the entire tempera¬ 
ture range. However, at 29° C. only two plants showed any definite 
tissue destruction. Such lesions as were observed on the remaining 
twenty plants at this temperature consisted of but slight browning of 
the outer stem tissue. The degree of damage was much increased at 
27 0 , and at 24 0 a severe decrease in crop resulted. Though not expressed 
in the table or the curves, the maximum degree of injury occurred, 
without doubt, at temperatures of 18 0 and 21 0 . At these temperatures 
the plumules of the embryos were entirely destroyed and the hypocotyl 
of the seedlings were in many cases decayed. Although no plants 
appeared above the surface of the soil at 13 0 and 15 0 , the tissue de¬ 
struction of the hypocotyl, which had made considerable growth at 
these temperatures, was not as great as at 18 0 and 21 0 . 
Experiment 2.—As is evident from results presented, the conditions 
under which the plants were grown in Experiment 1 were so severe as 
to allow of no accurate quantitative expression of the degree of damage 
in the soil at and below 21 0 C. In an attempt to reduce the severity 
of these conditions, and in order to secure a more definite idea of the 
effects of the fungus on the bean at these lower temperatures, the in¬ 
oculated and uninoculated soil used for Experiment 1 was emptied 
into separate piles, each diluted with twice its weight of unsterilized 
garden soil, and separately mixed. Sixteen cans were then refilled and 
temperatures adjusted. Fifteen seeds were again planted 2 inches deep 
in each of the 16 cans. 
At the time the data were taken, 16 days after planting, all plants 
were above ground, except those grown at 9.4 0 C. However, these 
were well germinated. At 15 0 and 18 0 the plants in the inoculated soil 
appeared somewhat irregular in height, but otherwise they could not 
be distinguished from those grown in the uninoculated soil. The results 
of the examination of the underground parts are recorded in Table VII 
and are shown graphically in figure 5. 
Under these less severe conditions, the damage to the stems was 
limited to the soil temperatures below 26.5° C. Severe injury occurred 
only in the soil held at 12 0 , 15 0 , 18 0 , and 21 0 , while the plumule de¬ 
struction was noted only at 12 0 and 15 0 . The highest percentage of 
stems showing lesions, together with the most severe type of tissue 
destruction, was found at 18 0 , although because of injury to the growing 
points, a greater total intensity of injury is shown at 15 0 . 
Table VII .—Effects of soil temperature on the pathogenic action of Corticium vagum 
on the bean (.Experiment 2) 
Temperature 
at depth of 
x inch. 
Number 
of seeds 
planted. 
Number 
of plants 
grown in 
uninocu¬ 
lated 
soil. 
Plants grown in inoculated soil. 
Total 
num¬ 
ber. 
Number 
slightly 
injured. 
Number 
severely 
injured. 
Num¬ 
ber 
cut 
off. 
Number 
un¬ 
injured. 
Per¬ 
cent¬ 
age 
injured. 
Inten¬ 
sity 0 f 
injury. 
Average 
dry 
weight of 
healthy 
plants. 
°C. 
Gm. 
9 * 4 . 
20 
15 
16 
4 
II 
25. 0 
25. 0 
O. 025 
12-5 . 
20 
18 
18 
8 
I 
1 
8 
55 - S 
72. 0 
. 066 
15-0 . 
20 
17 
15 
6 
I 
3 
5 
66.6 
113. 2 
. 101 
18. 0. 
20 
18 
16 
8 
3 
5 
68 . 45 
IO6. I 
• 131 
21. 0. 
20 
18 
18 
5 
I 
12 
33-3 
38- 7 
• 143 
23* 6. 
20 
16 
19 
5 
14 
26. 32 
26. 32 
. 190 
26. c. 
20 
19 
19 
19 
. 200 
20. 7. 
20 
19 
19 
!9 
. 206 
✓ 1 
