Feb., 1923] CLAYTON — TEMPERATURE AND FUSARIUM WILT 
79 
high) of the Mangus variety or Chalk’s Early Jewel were transplanted into 
the containers, one plant of each variety being set in each container. Usu¬ 
ally six such pots were held at each temperature until the infected plants 
at the optimum temperature for the disease were completely wilted. This 
time was a month or more, and meanwhile the progress of the disease was 
noted daily. 
The plants used in these experiments were grown in three-inch pots until 
they were transferred to the inoculated soil. In transplanting, no con¬ 
siderable amount of soil was removed from the roots by washing or other 
methods, but the whole root system was kept as nearly intact as possible. 
A few of the smaller roots were necessarily injured, but infection was not 
more abundant in the plants bearing such roots than in those inoculated in 
the pots in which they were grown, and which, therefore, had no rootlets 
injured by transplanting. 
Soil-temperature Experiments 
1. Experiments in which the air temperatures were uniform 
and the soil temperatures varied 
Three experiments, which for convenience may be referred to as I, II, 
and III, were conducted at a uniform air temperature and different soil 
temperatures. Only one of these experiments, however, need be described 
in detail, as the responses of the disease to different temperatures were the 
same in all trials. 
Experiment III. Nine different tanks held at temperatures of 19 0 , 21 0 , 
22 0 , 23 0 , 24 0 , 28°, 31 0 , 33 0 , and 35 0 C., respectively, were used in this experi¬ 
ment. Each tank accommodated six culture cans with two tomato plants 
in each can; three of these cans contained inoculated, and the other three 
uninoculated soil. 
Table i. Results showing percentages of infection which occurred in plants grown in uni¬ 
formly infected soil and held at soil temperatures ranging from ig° to 35 0 C. {Experiment 
III); when leaves were wilted and bundles blackened in stems, roots, and leaves, plants 
were counted as infected. 
Treatment 
Results 
Temperature 
No. Plants 
No. Plants 
No. Days 
No. Days 
Average No. 
0 C. 
Used 
Infected' 
before 
before 
Days before 
1st Infection 
Last Infection 
Infection 
19. 
6 
1 
29 
— 
29.0 
9 T 
6 
0 
_ 
_ 
__ 
22. 
6 
5 
22 
29 
25.0 
23. 
6 
4 
21 
29 
25-5 
24. 
6 
5 
20 
28 
23.0 
28. 
6 
6 
12 
22 
14.5 
31. 
6 
6 
16 
22 
15-5 
33. 
6 
1 
26 
— 
26.0 
35. 
6 
0 
— 
— 
— 
