Fusariiim in Tuber Rot and Wilt of Potato 
43 
4. Under field and storage conditions Fusariiim oxysporum is 
more probably responsible for wilt than is F. trichothecioides, and 
the latter more responsible for tuber rotting. 
3. The optimum and maximum temperatures of Fusariiim oxy- 
sporum are higher than those of F. trichothecioides. F. trichothe- 
cioides, however, grows well at 8-10^ C, while F. oxysporum does 
not. These facts may explain in part the fact that F. oxysporum 
produces more wilt than F. trichothecioides, and that the latter 
causes more tuber rot. 
6. Fusariurn oxysporum has a more rapid, superficial, and 
spreading habit of growth than has F. trichothecioides. This may 
be associated with a greater oxygen requirement for F. oxysporum, 
and may account for the frequenting of xylem elements by this 
fungus. 
7. Both organisms possess a striking ability to use the most 
diverse carbon materials as carbon sources in their metabolism. 
Fusariiim oxysporum has a greater range in its ability, and can 
utilize the materials more readily, although not so completely as 
does F. trichothecioides. 
8. Fusariiim oxysporum is less subject to inhibition in growth 
and intoxication than is F. trichothecioides. 
9. Solanin is not toxic to either organism, although it seems to 
inhibit somewhat the growth of Fusariiim trichothecioides. 
The writer acknowledges his indebtedness to Dr. E. ]\Iead 
Wilcox and to Dr. \\Tllia:m Crocker. They not only made this 
research possible, but they gave freely of advice and criticism, and 
lent encouragement by their interest in the progress of the investi- 
gation. 
AGRICULTURAL EXPERIMENT STATION 
L'NIVERSITY OF NEBRASKA 
LITERATURE CITED 
1. Appel. Otto, Untersuchungen iiber die Schwarzbeinigkeit und die durch 
Bakterien hervorgerufene Knollenfaule der Kartoffel. Arb. Biol. Abth 
Land- u. Forstw. Kais. Gesund. .3 :.362-432. pi. i. figs. i-ij. 1903. 
2. . Leaf roll diseases of the potato. Phytopathology .5:139-148. 1915. 
