Fusarium in Tuber Rot and JJ^ilt of Potato 
9 
Problem and method of attack 
In the spring and summer of 1914 the writer discussed the 
Fusarium situation as outhned by \\'ollenwei]er with Dr. E. M. 
Wilcox and Dr. William Crocker. The former sugges-ed 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 \\'oLLEX WEBER exist. then potato parenchyma must possess 
either an absolute or an effective immunit}' toward Fusarium spp. 
of the Elegaxs section, and that Fusarium spp. of the Discolor 
section are either aljsolutely 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, 
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 
of the potato and the influence of external factors upon these is 
well illustrated by the studies of Appel and Kreitz (1, 3 ) on the 
efficacy of the cork layer in checking bacterial invasions of the 
tuber. Considerations of time and equipment limitations made it 
obligatory that the scope of the work be limited to a study of a 
few representative 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 n.iuch 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 
