470 
Journal of Agricultural Research 
Vol. XXI, No. 7 
slow growth of the shoots and the protection offered in the sinus area 
apparently permitted the collection of liyphae and finally the killing of 
the bud or growing point of the stems. An explanation is thus suggested 
for the abundance of such localized tissue destruction at the lower tem¬ 
peratures where growth of the young shoot is seriously retarded. It 
further suggests a possible genetic relation between the growing-point 
injury and the lesions occurring elsewhere on the stem. 
The results agree with those of experiment 2 in showing a decidedly 
higher percentage of diseased stems and a more severe type of lesion in 
the unsterilized than in the sterilized soil (Table IV and fig. 3). 
Table IV. — Percentage of diseased stems in sterilized and unsierilized soil 
EXPERIMENT 3 
Temperature (° C.). 
Unsteril¬ 
ized soil. 
Sterilized 
soil. 
0.1... 
a 5° 
5^ 
72 
90 
5 2 - 3 
28. 9 
23 
I2 -5 
14.2 
33- 3 
34- 8 
35- 8 
J 3-3 
4 
II.6. 
14.7. 
18. 
21. 
23.7. 
27. ... 
70 ..... 
“The water content of the unsterilized soil used in the experiment was found to be 20.4 per cent of its 
dry weight. No determinations were made of the change in the water relation of the soil due to ster- 
lization. 
Experiment 4.—This experiment differed from experiment 3 only in 
the use of Early Ohio seed. As adequate sclerotia occurred on the sur¬ 
face of the potatoes used for planting, the same tubers served both for 
an index and for the conveyance of the inoculum. 
Tabl,E V .—Effects of growing Early Ohio potatoes at various temperatures in soil inocu¬ 
lated with sclerotia of Corticium vagum 
EXPERIMENT 4 
Temperature 
(°C.). 
Number 
of sets 
planted. 
Number 
of stems 
# grown 
in unin¬ 
oculated 
soil. 
Stems grown in inoculated soil. 
Total 
number. 
Number 
slightly 
injured. 
Number 
severely 
injured. 
Number 
cut off. 
Number 
unin¬ 
jured. 
Percent¬ 
age 
injured. 
Intensity 
of injury 
(points). 
8.8. 
3 
s 
25 
5 
I 
11 
24.0 
28.O 
11. 8. 
3 
10 
33 
10 
5 
18 
45-4 
63.0 
15-3 . 
3 
II 
2 3 
8 
4 
11 
52.1 
69.6 
18.2. 
3 
12 
22 
3 
5 
2 
12 
45-5 
86.6 
20.8. 
3 
9 
24 
5 
2 
I 
l6 
33-3 
49*7 
2 3-7 . 
3 
9 
25 
7 
3 
15 
40.0 
52.0 
27-4 . 
3 
9 
26 
4 
1 
21 
19.2 
22.9 
30. 
O 
24 
24 
O 
7 
1 
/ 
