Fusarium in Tuber Rot and Wilt of Potato g 



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. It 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 Discolor 

 section are either absolutely or practically unable to produce vascu- 

 lar mycoses or wilts. 



The purpose of this research was twofold: (1) to determine 

 whether such a sharp biological contrast 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 phase might 

 involve a great many considerations, such as the structural, com- 

 positional, and metabolic nature of both host and parasite, as well 

 as the relation of environmental factors to these. The important 

 role played by the structural and compositional peculiarities of the 

 potato and the influence of external factors upon these is well 

 illustrated by the studies of Appel and Kreitz (i, 3) on the efficacy 

 of the cork layer in checking bacterial invasions of the tuber. 

 Considerations of time and equipment limitations made it obliga- 

 tory that the scope of the work be limited to a study of a few repre- 

 sentative strains of the groups. 



The writer is under obligation to the Departments of Agricul- 

 tural Chemistry, Horticulture, and Experimental Agronomy of the 

 University of Nebraska Experiment Station for the use of materials 

 and equipment; to Miss Ethel Beaty for help 'in much of the 

 laborious routine; to Dr. Florence A. McCormick for valuable 

 help in the anatomical and 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), and with 



