466 
grams) dissolved in a liter of Coons’s agar. 
The other concentrations were prepared 
from this stock diluted with Coons’s agar. 
All dilutions were made immediately after 
the agar had been autoclaved, and the 
Petri dishes were poured immediately 
after the dilutions had been made. This 
procedure was necessary because it was 
found that Coons’s agar containing copper 
salts, if remelted after being allowed to 
solidify, would not resolidify. Inoculum 
was prepared and the Petri dishes were 
inoculated in the same manner as that 
described for the aniline dye tests. 
Ittinois NaturAL History SurvEY BULLETIN 
Vol. 26, Art. 6 
The reactions of the 40 isolates of glad- — 
iolus Fusarium to copper sulfate are very — 
interesting because they show extreme va- | 
riability in tolerance to the salt, figs. 11 
and 12. One isolate, 45-74, produced 
measurable growth in the 7/100 concen- 
tration. Seven isolates produced only — 
traces of growth in the 7/5000 concen- 
tration and two isolates produced measur- 
able growth in only the 47/7000 con- 
centration, table 6. Although the reactions 
of the various isolates to copper sulfate 
failed to distinguish between isolates of © 
Fusarium from the three disease forms, — 
Table 7.—Reactions* of isolates of the gladiolus Fusarium to four different molar (M)_ 
concentrations of copper chloride in Coons’s agar.} 
ISOLATE 
CONCENTRATION OF CoppER CHLORIDE 
M/100 M/300 M/500 M/1000 
0 0 0 0 
0 0 0 0 
11.301 12.101 12.301 12.301 
0 0) 0 tr 
0 0 0 0 
0 0 0 0 
0 0 0 0 
0 0 0 or 
tr 14.301 15.001 15.001 
0 0 0 0 
0 tr 11.301 15.001 
0 0 0 0 
13.301 14.301 15.001 15.001 
0 0 0 tr 
0 0 0 11.000 
tr 14.301 15.001 15.001 
0 0 0 tr 
0 0 0 0 
12.301 15.301 15.301 15.001 
tr 13.301 14.301 15.001 
0 11.301 12.301 13.301 
0 14.301 15.001 15.001 
0 0 0 0 
0) 13.301 13.301 15.001 
0 tr 13.301 15.001 
0 13.311 14.001 15.001 
@) 15.001 15.001 15.001 
0 0 0 0 
tr 15.001 15.001 15.001 
tr 13.301 15.301 15.001 
0 0 0 0 
0 0 0 0 
11.301 15.301 15.301 15.001 
0 0) 0 tr 
tr 15.301 15.001 15.001 
tr 13.301 14.001 15.001 
0 0 0 0 
0 0 0 0 
0 0) 0 0 
0 0 0 0 
*Reactions are expressed in the numbering scheme of Coons & Strong (1931), as explained in the text. 
7See table 3 for control readings. 
