September, 1955 
and probably more biological races of F. 
oxysporum f. tracheiphilum Sny. & Hans. 
on the basis of pathogenicity on varieties 
of soybeans and cowpeas. 
Studies on the relation of culture types 
and pathogenicity of the 40 isolates of 
gladiolus Fusarium listed in table 1 were 
undertaken by the writer with the hope of 
finding a possible relation between colony 
type, disease form, and degree of virulence. 
Methods of determining virulence are de- 
scribed under “Pathogenicity Tests.” 
Culture Types of the Gladiolus 
Fusarium.— Original isolations from dis- 
eased gladiolus corms were made on po- 
tato dextrose agar. Growth forms of the 
ForsBerc: Fusarium Disease or GLADIOLUS 471 
original cultures were not recorded for all 
isolates. However, 23 of the _ isolates 
were classified as belonging to the raised, 
intermediate, or appressed types on the 
basis of their aerial mycelium, table 10. 
Later, all isolates were grown on the me- 
dium found by Wellman (1942) to give 
more distinctive reactions between cul- 
tural variants. This medium, referred to 
as Wellman’s agar in the present investiga- 
tion, has the following composition: pro- 
teose peptone 5.0 grams, dihydrogen pc 
tassium phosphate 0.5 gram, magnesium 
sulfate 0.5 gram, maltose 15.0 grams, fer- 
rous sulfate 0.03 gram, agar 12.0 grams, 
water 1,000.0 milliliters. 
Fig. 13—Raised, appressed, and intermediate growth forms of vascular isolates of Fusarium 
grown on Wellman’s agar. The extreme raised and extreme appressed forms are shown in cul- 
tures 45-73 and 49-15, respectively. 
Cultures are 20 days old. 
