September, 1955 
ForsBErRG: Fusarium Disgase or GLADIOLUS 
455 
Table 2.—Growth of six isolates of the gladiolus Fusarium on Coons’s agar at various tem- 
peratures. Incubation period 160 hours. 
Mean oF Diameters (MILLIMETERS) oF Two CoLoniEs 
Temperature, Decrees C. Brown Rot Isolates Vascular Isolates Basal Dry Rot Isolates 
45-75 50-22 45-73 50-24 47-3 50-23 
=o onto eee er 0.0 0.0 0.0 0.0. 0.0 0.0 - 
Bis: 0 .0* 0.0 0.0 0.0* 0.0 0.0 
A DS222) 5 oh 6 cree Rae ene 52.0 63.0 66.0 50.0 58.0 55 
25 4g SOR Oe 67.0 78.0 83.0 63.0 64.0 63.0 
Lf. . gS del eee 78.0 85.0 90.0 68.0 73.0 74.0 
BRE BRST? </ha 6s fs os Seo 74.0 87.0 90.0 71.0 75.0 75.0 
SOR Soe Se Geen 43.5 49.0 57.0 50.0 49.0 49.0 
22. 36 (Med ane HOES) 48.0 54.0 47.0 48.0 47.0 
Jo ota 525 8.5 7.0 HSS 6.0 6.0 
20. 8S A Ee eee 25 3).5) 3.0 525 4.0 3.0 
31D) So Saute G8 oes ae 0.0 0.0 0.0* 0.0 0.0 0.0* 
4) SOS GaSe Cee 0.0 0.0 0.0 0.0 0.0 0.0 
*A trace of growth insufficient for measurement appcared in these plates. } : 
were selected for comparison in pathoge- 
nicity tests and physiological studies. Sev- 
enteen of these isolates were obtained from 
corms with the vascular, 16 from corms 
with the brown rot, and 7 from corms 
with the basal dry rot form of the disease. 
They will be referred to hereafter as vas- 
cular, brown rot, and basal dry rot or basal 
rot isolates. 
The original isolations were made on 
Difco potato dextrose agar. Single-spore 
isolates were obtained from spore suspen- 
sions in sterile water blanks; each suspen- 
sion was diluted until a desired spore con- 
centration was reached, and then the di- 
luted suspension was poured over the sur- 
face of a thin film of 2 per cent water agar 
in a Petri dish. After a few seconds the 
excess suspension was poured off and the 
plate was allowed to stand for 15 to 16 
hours. The Petri dish was then placed on 
the stage of a dissecting microscope, and 
germinated spores were picked off singly 
on the tip of a needle and transferred to 
potato dextrose agar slants. Progenies 
from these single-spore isolates were used 
in the infection experiments and _ physio- 
logical studies. The sources of all isolates 
are listed in table 1. 
Comparisons of isolates from the three 
forms of the disease were made on the fol- 
lowing bases: reactions to temperature, 
reactions to aniline dyes, reactions to cop- 
per salts, reactions to mercuric chloride, 
color reactions on steamed rice, growth 
types on Wellman’s differential medium, 
pH changes produced in liquid media, 
spore measurements, inoculation tests in 
the laboratory, and inoculation tests in the 
greenhouse. 
PHYSIOLOGICAL STUDIES 
Physiological studies of the gladiolus 
Fusarium were made by the writer in an 
effort to determine if isolates from the 
three forms of the disease could be distin- 
guished by their physiological characters. 
Influence of Temperature on 
Growth Rates 
Massey (1926) reported that the glad- 
iolus Fusarium studied by him grew in cul- 
ture at temperatures ranging from 5 de- 
grees to 35 degrees C.; the optimum was 
27.5 degrees. McCulloch (1944) reported 
that the Fusarium she studied grew at tem- 
peratures ranging from less than 3 de- 
grees to about 3+-36 degrees C.; the op- 
timum temperature range was 23-26 de- 
grees C. 
In the present investigation, the influ- 
ence of temperature on the growth rates 
of the gladiolus Fusarium was studied on 
two isolates grown from each disease type 
on Coons’s agar in Petri dishes through a 
series of 12 temperatures. The inoculum 
for the Petri dishes was prepared in the 
following manner to obviate erratic be- 
