Fusarium Disease of Gladiolus: 
[ts Causal Agent 
HE Fusarium disease of gladiolus 
is one of the most destructive ma'‘a- 
dies known to affect flower crops. 
At a conference held in January, 1953, at 
Cleveland, Ohio, under the auspices of the 
Joint Research Committee of the North 
American Gladiolus Council and _ the 
North American Commercial Gladiolus 
Growers, the concensus of those present 
was that the Fusarium disease is the most 
important g'adiolus disease in the United 
States (Ryan 1953). The disease causes 
large losses to commercial gladiolus grow- 
ers in Illinois, Indiana, Michigan, Califor- 
nia, eastern Washington, and a!l of Ore- 
gon except the northern part. It causes 
an estimated loss of 114 to 2 million dol- 
lars per year in Florida alone. Because 
the Fusarium disease is corm-borne and be- 
cause many of the corms grown in Illinois 
are shipped to Florida and planted there 
for winter flower production, the fate of 
the crop in Florida is of importance to 
growers in Illinois as well as to growers 
in Florida. Only one commercial gladio- 
lus-growing area in the United States is 
not seriously troubled with the Fusarium 
disease. This is the cool region in western 
Washington where, according to Gould 
(1949), Fusarium rot is uncommon except 
on recently introduced stocks. 
ACKNOWLEDGMENTS 
The writer wishes to express his sincere 
appreciation to all who have assisted in any 
way during the course of this investiga- 
tion, the greater part of which was pre- 
sented as a thesis submitted to the Gradu- 
ate College, University of Illinois, Ur- 
bana, in partial fulfillment of the require- 
ments for the degree of Doctor of Philos- 
ophy in Plant Pathology. He is especially 
grateful to the late Dr. Leo R. Tehon, for 
many years head of the Section of Applied 
JUNI US: “by. FOR S biG 
Botany and Plant Pathology at the Nat- 
ural History Survey, for his guidance and 
many helpful suggestions during the course 
of the investigation and the preparation 
of the manuscript. Helpful suggestions 
were made by Dr. Wayne M. Bever, Pro- 
fessor of Plant Pathology, University of 
IL:inois, and Agent, United States Depart- 
ment of Agriculture. The photographic 
work was done by Mr. William E. . lark, 
Assistant Technical Photographer of the 
Natural History Survey, and by Mr. Ray 
R. Hamm, Manager of the University of 
Illinois Photographic Laboratory. Several 
present or former members of the Natural 
History Survey staff made valuable con- 
tributions. Mr. James W. Curfman drew 
the graphs. Mrs. Rovenia Fitz-Gerald and 
Mrs. Virginia Lee Johnstone assisted in 
preparation of the manuscript. Mr. James 
S. Ayars and Mrs. Blanche P. Young 
read all or parts of the manuscript. Each 
offered valuable criticism. The author is 
especially grateful to his wife, Edith L. 
Forsberg, for her encouragement and help 
in many ways during the course of this 
work. 
HISTORY OF THE DISEASE 
The disease of gladiolus which 1s cal'ed 
herein the Fusarium disease is a much mis- 
understood malady which exists in three 
forms. These forms have been designated 
as the vascular, the brown rot, and the 
basal dry rot types, each of which has beer 
described as a distinct disease by various 
workers. The disease was first recognized 
in the early 1920’s but it probably existed 
prior to that time. W. A. Pryal (1909), 
a California grower, published a rote in 
which he described an interior corm rot 
and leaf yellowing of gladiolus, but no 
proof was presented that the disease was 
caused by a fungus of the genus Fusarium. 
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