20 
Research Biilletm No. p 
F. ox\sponim makes greater headway than the other and there 
causes a vascular mycosis more frequently, which accounts for its 
designation as a vas'-ular parasite (figs. 7 and 8). 
Discussion. — If plants, ('experimentally inoculated, showed 
only light symptoms to begin with, most of them continued their 
growth with symptoms less severe than those shown in the field. 
If they showed severe symptoms early, these proved more severe and 
^ B 
FiG. 6. — Wilt and death of potato plants produced in laboratory with 
Fusariuni trichothccioidcs. 12 days after inoculation; Early Ohio variety; 
wilting is restricted to tlie side to which inoculum was applied. 
more rapidly fatal than those in the field. The organisms in the 
field work much more insidiously, attacking the roots of the plant 
slowly but progressively, and permitting the plant, except in extreme 
cases, to readjust for its water requirements. These readjustments 
manifest themselves in the curling and rolling phenomena 
(figs. 4 and 9). 
Potato plants in the irrigated sections show this phenomenon 
nicely. As long as cultivation and irrigation are maintained, the 
plant develops new roots progressively higher up, and the infected 
