Fusarium in Tuber Rot and Wilt of Potato 43 



4. Under field and storage conditions Fusarium oxysporum is 

 more probably responsible for wilt than is F. trichoihecioid.es, and 

 the latter more responsible for tuber rotting. 



5. The optimum and maximum temperatures of Fusarium 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. Fusarium 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. 

 Fusarium oxysporum has a greater range in its ability, and can 

 utilize the materials more readily, although not so completely as 

 does F. trichothecioides. 



8. Fusarium 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 Fusarium trichothecioides. 



The writer acknowledges his indebtedness to Dr. E. Mead 

 Wilcox and to Dr. William 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 

 University 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. 1. figs. 1-15. 1903. . 



2 - , Leaf roll diseases of the potato. Phytopathology 5:139-148. 1915. 



