500 
SUMMARY 
Three forms of the Fusarium disease 
of gladiolus, known as the vascular, 
brown rot, and basal dry rot forms, have 
been described by other workers. The 
agent or agents which cause these disease 
forms have been assigned various specific 
names, with the result that the exact rela- 
tion of the different symptom types and 
their causal agent or agents has been in a 
state of confusion. 
The purpose of this investigation was 
to rectify the confusion by determining if 
strains of Fusarium producing different 
symptoms could be fitted into well-defined 
groups on the basis of their pathogenicity 
and physiological characters. 
From several hundred isolates of Fu- 
sarium that had been cultured from dis- 
eased gladiolus corms, 40 isolates were 
selected for comparison in pathogenicity 
tests and physiological studies. Compari- 
sons of isolates from the three disease 
forms were made by means of their reac- 
tions to temperature, reactions to aniline 
Itutinois NATURAL History SURVEY BULLETIN 
dyes, reactions to copper salts, reactions 
to mercuric chloride, color reactions on 
steamed rice, growth types on differential 
media, pH changes produced in liquid 
media, spore measurements, and tendency 
to reproduce the same or different disease 
forms in inoculated plants and corms. 
The isolates varied a great deal in their 
reactions in these tests, but no definite pat- 
tern for association of variables could be 
determined ; the variations seemed to occur 
independently. The isolates did not fall 
into well-defined groups; the isolates from 
the three disease forms could not be dis- 
tinguished by any of the tests used. The 
pathogenicity tests showed that a single 
isolate is capable of producing more than 
one form of the disease. 
The evidence obtained in these studies 
shows that strains of the gladiolus Fu- 
sarium are extremely variable and that 
some of them apparently are quite unsta- 
ble. It is proposed that all forms of the 
gladiolus Fusarium be included under the 
name Fusarium oxysporum f. gladioli 
(Massey) Snyder & Hansen. 
Vol. 26, Art. 6 
ee ed or an 
Cpa ey ee 
