Fusarium in Tuber Rot and Wilt of Potato 9 



Problem and method of attack 



In the spring and summer of 1914 the writer discussed the 

 Fusarium situation as outlined by Wollenweber with Dr. E. M. 

 Wilcox and Dr. William Crocker. The former suggested that 



the whole situation ought to be gone over, and the latter that it 

 would be of interest to search for the physiological basis of this 

 alleged biological contrast, h is clear that, if the strict categories 

 of Wollenweber exist, then potato parenchyma must possess 

 either an absolute or an effective immunity toward Fusarium spp. 

 of the Elegans section, and that Fusarium spp. of the DlSi 

 -,, tii n are either absolutel) or practically unable to produce vascu- 

 lar mycoses or wilts. 



The purpose of this research was twofold: ill to determine 

 whether such a sharp biological contrasl exists; and (2) to deter- 

 mine what is the physiological basis for such a contrast. Experi- 

 mental infections of potato plants and tubers were used for the 

 first phase of the problem. It was clear that the second p 

 might involve a great many considerations, such as the structural, 

 compositional, and metabolic nature of both host and parasite, as 

 well as the relation of environmental factors to these. The im- 

 portant role played by the structural and compositional peculiarities 

 i f the potato and the influence of external factors upon thi 

 well illustrated by the studies of Apfel and Kreitz (1, 3i on the 

 efficacy of the cork laver in checking bacterial invasions of the 

 tuber. Considerations of time and equipment limitations made it 

 obligatory that the scope of the work he limited to a study of a 

 few representative strains of the groups. 



The writer is under obligation to the Department- of Agricul- 

 tural Chemistry, Horticulture, and Experimental Agronorm of 

 the University of Nebraska Experiment Station for the use of 

 materials and equipment : to Miss Ethel Beaty for help in much "f 

 the laborious routine: to Dr. Florence A. McCormick for ealuablc 

 help in the anatomical ami microtechnical phases of the problem; 

 and to Mr. R. A. Dawson for help in preparing the photographs. 



The writer decided to work with F. oxysporum as represent 

 ative of the vascular parasite section (Elegans), ami with 



