456 
havior traceable to size or character of in- 
oculum: coarse white cotton thread was 
cut in pieces about 114 inches long and 
autoclaved in distilled water. ‘These pieces 
were laid on an agar slant, which was then 
inoculated from the isolate to be tested. 
About a week after fungus growth had 
overrun the cotton threads, the threads 
were lifted from the culture, scraped clean 
of adhering agar, and cut with sterile scis- 
into sections, each about 2 milli- 
meters long. One piece of Fusarium-in- 
sors 
fested thread was placed in the center of 
Immediately after inoculation 
each dish. 
Ittinois NATURAL History SURVEY BULLETIN 
Vol. 26, Art. 6 
the dishes were placed in electrically con- 
trolled incubators kept at temperatures 
shown in table 2 and left for 160 hours. 
At the end of the incubation period the 
diameters of the colonies were measured, 
table 2. ‘wo dishes of each isolate were 
used for each temperature. Relative sizes 
of the colonies grown at different temper- 
atures are shown in figs. 5, 6, 7, and 8. 
None of the isolates grew at the 1-3 de- 
gree C. temperature range, table 2, and 
only brown rot isolate +5-75 and vascular 
isolate 50-24 showed traces of growth at 5 
degrees C. Since the next higher tempera- 
Fig. 5.—Six isolates of Fusarium grown on Coons’s agar for 160 hours at the following tem- 
peratures: 20-22, 24, 27-28 degrees C. (top row in each set of six dishes, left to right) ; 30, 32, 
and 36 degrees C. 
(bottom row in each set, left to right). Isolates 45-73 and 50-24 are vascular 
isolates, 45-75 and 50-22 are brown rot isolates, 47-3 and 50-23 are basal dry rot isolates. 
