PLATE 140 
Influence of the presence of wilt-producing fungi in seed potato tubers on the plants 
grown therefrom. All plants photographed August 22, 1917. 
A. —Plant at left wilting and dying prematurely from attack of Verticillium albo- 
atrum demonstrated to be present in the seed potato before planting. Plant at right 
was grown from a tuber from which no organism was secured in culture. The two 
seed potatoes each weighed 2 ounces, and it is interesting to note that both were pro¬ 
duced by one plant affected by Verticillium-wilt. Variety Up-to-Date. 
B. —Two American Wonder potato plants grown from the stem-end (plant at left) 
and eye-end (plant at right) halves of a 4-ounce tuber from which Fusarium oxysporum 
was isolated before planting. Neither of the plants showed wilt during the season 
and none of the tubers were infected by this fungus when cultured after harvest. The 
contrast between the amounts of disease in the plants grown from tubers affected by 
F. oxysporum and by V. albo-atrum was striking, for so few of the former became 
noticeably attacked. The latter, on the other hand, were generally wilted. 
C. —Two American Wonder potato plants grown from the two longitudinal halves of 
a 5-ounce tuber from which no organism was isolated in culture. No wilt developed 
during the season. 
