September, 1955 FORSBERG: 
monosporous isolations were made from an 
isolate derived from a diseased plant, all 
cultures were alike and of a form that pro- 
duced abundant aerial mycelium on which 
conidia, mostly nonseptate, were borne 
rather sparsely. He called this form the 
wild type. Cultural variants that were 
derived from the wild type were consid- 
ered to be laboratory mutants. Miller con- 
tended that the taxonomy of Fusarium 
should be based only on wild types and not 
on laboratory mutants. 
The classification of Wollenweber & 
Reinking (1935) is based on the view 
that the macroconidia are the spore types 
on which species descriptions should be 
based and that those Fusaria which do not 
produce such spores when isolated from 
nature may be induced to do so by fre- 
quent cultural transfers. Such transfer- 
ring gives rise to a cultural state char- 
acterized by abundant production of 
macroconidia, a condition that has been 
called “normal culture,” “high culture,” 
“Normkultur,” and ‘‘Hochkultur.” Miller 
contended that this methed resu!ts in dis- 
placement of the wild type by mutants. 
According to Miller, most of the species 
descriptions appearing in the literature 
have been based on laboratory mutants 
rather than on natural types. Hence, he 
considered the classification of Wollen- 
weber & Reinking unsatisfactory. The 
Snyder & Hansen (1940, 1941, 1945) 
revision disregards morphological criteria 
and places primary emphasis on the host 
relationship. Miller centended that this 
system also is unsatisfactory, stating that 
if proper cultural methods are emp!oyed 
the morphology cf these organisms will 
be found sufficiently constant to warrant 
an attempt at morphological classification. 
He based this statement on two facts: 
(1) his original isolates were all of the 
raised type and (2) he was able to main- 
tain this type by a soil culture technique 
in which the fungus was kept in a dried, in- 
active condition for long periods of time. 
From these two facts he concluded that 
variants of the types found in laboratory 
cultures do not occur in nature, or at 
least that variants are very rare. These 
conclusions do not agree with the report 
of Orton (1935), who found that several 
strains of Fusarium niveum Smith may 
FusartuM DISEASE oF GLADIOLUS 
499 
change as readily in soil as upon labora- 
tory media. 
While an extensive study of the occur- 
rence of changes in culture form of the 
gladiolus Fusarium was not made by the 
writer, such changes were observed, table 
10. Since the raised, appressed, and in- 
termediate forms were obtained in orig- 
inal isolations of the gladiolus Fusarium, 
it must be assumed that all of these forms 
occur in nature and that the wild types 
of this fungus are not all of one form. 
The main object of this investigation 
was to determine if strains of Fusarium 
obtained from gladiolus corms having dif- 
ferent disease symptoms could be fitted 
into well-defined groups on the basis of 
their pathogenicity and _ physiological 
characters. The isolates used in these 
studies do not fall into we'l-defined 
groups. Also the pathogenicity tests show 
that a single isolate is capable of produc- 
ing more than one form of disease. Evi- 
dence obtained in the other tests in this 
investigation shows that the strains of 
the gladiolus Fusarium are extremely var- 
iable and some apparently are quite un- 
stable. No definite pattern for ascocia- 
tion of the many variables could be deter- 
mined; the variations seem to occur inde- 
pendently. 
It was not intended that this paper 
should enter the controversy on the rela- 
tive merits of the two available systems 
of c'assifying Fusaria. But, as both sys- 
tems have been used in previous studies 
of the Fusarium disease of gladiolus, and 
at least two specific names under one sys- 
tem have been used for strains of the fun- 
gus associated with different forms of the 
disease, it becomes necessary to take a 
definite stand regarding the nomenclature 
and taxonomy of the gladiolus Fusarium. 
Since this investigation failed to establish 
the existence of well-defined strains of a 
Fusarium associated with the different 
forms of the disease, it seems most logical 
to regard all variants as members of a 
single species. Because the system of Sny- 
der & Hansen is better suited for classi- 
fication of this type of organism, it Is pro- 
posed that all forms of the gladiolus Fu- 
sarium be included under the name Fu- 
sarium oxysporum £. gladioli (Massey) 
Snyder & Hansen. 
