458 
Isolate 50-23 
AVERAGE COLONY DIAMETER IN MILLIMETERS 
te) 5 10 15 
TEMPERATURE, DEGREES CENTIGRADE 
Fig. 8.—Effect of temperature on the colony size of two basal dry rot isolates of Fusarium 
grown 160 hours on Coons’s agar. 
several days. Five of the six isolates grew 
when moved to the lower temperature. 
Basal dry rot isolate +7-3 apparently had 
been killed by the 160-hour exposure to 40 
degrees C. 
In these studies the general shape of the 
curves of growth responses of all isolates 
to various temperatures was of the same 
general pattern, figs. 6, 7, and 8. The 
basal dry rot isolates agreed much more 
closely in their responses to temperatures 
than did the isolates from the other disease 
forms. The vascular isolates showed the 
greatest divergence in responses to temper- 
atures. Isolates from the three disease 
forms could not be distinguished by their 
growth responses to various temperatures. 
Reactions to Aniline Dyes 
The 40 isolates of the gladiolus Fusar- 
ium listed in table 1 were grown on 
Coons’s agar containing various concentra- 
tions of the aniline dyes malachite green, 
brilliant green, and crystal violet, accord- 
ing to the method developed by Coons & 
Strong (1931). 
The malachite green and brilliant green 
media were made from preparations of 
stock agar containing 10 milliliters of 0.5 
I~tinors NaTuRAL History SuRvEY BULLETIN 
Isolate 47-3 
Vol. 26, Art.6 © 
25 30 35 40 
per cent dye solution per liter of Coons’s 
agar. For each medium, four concentra-_ 
tions, tables 3 and 5, were prepared from — 
the stock agar diluted with appropriate 
amounts of sterile, melted Coons’s agar. 
The crystal violet stock agar was pre- 
pared from 100 milliliters of 0.5 per cent — 
dye solution added to a liter of Coons’s — 
agar, and the four concentrations, table 4, — 
were made from this stock. 
Inoculum was prepared in the manner 
described for the temperature studies. Four — 
isolates were grown in each dish. The — 
center of each quadrant of the dish was 
seeded with a 2-millimeter piece of Fu- 
sarium-infested thread. The cultures were — 
run in duplicate and were incubated for 10 — 
days at 25 degrees C. 
Readings of the Petri dish cultures were 
made in accordance with the decimal num- 
bering scheme used by Coons & Strong 
(1931). This scheme is as follows: 
Color of mycelium 
White 2 voi: ae 10. 
Ried; hice os De ee 20. 
Breadth of mycelial mat 
Wo growth: .....2%:.2 wee 
Very slight growth....... tr 
Sem: to: btm} 3 oie or eee ly 
1 cms tov 2:eminy ha eee Zs 
