VARIETAL SUSCEPTIBILITY OF BEANS TO RUST 1 
By F. D. Fromme, Plant Pathologist , and S. A. Wingard, Assistant Plant Pathologist, 
Virginia Agricultural Experiment Station 
INTRODUCTION 
The bean rust fungus, Uromyces appendiculalus (Pers.) Fries, is 
worldwide in distribution, being found practically coextensive with the 
distribution of its hosts throughout the North American continent and 
in the West Indies, South America, Europe, Africa, Asia, Japan, and 
Australia. In addition to its common host, Phaseolus vulgaris L., it occurs 
in North America on ten species of Phaseolus, two species of Dolichos, 
two of Strophostyles, and three of Vigna (i) . 2 It is an autoecious species 
with the full complement of spore forms. The aecia are of the cupulate 
type and are ,of rather rare occurrence, judging from the collections in 
herbaria. The writers have seen them in the field on only one occasion. 
The uredinia and telia are found during the summer and fall and are 
very common. The relative importance of the different spore forms in 
the overwintering of the rust has not been determined, but it seems 
likely that the teliospores, are of minor importance, at least under Vir¬ 
ginia conditions, and that the urediniospores are the most important 
factor in overwintering. 
In the opinion of the writers bean rust is commonly underrated as a 
limiting factor in bean production. The losses are indirect, being occa¬ 
sioned by decreased vigor due to foliage injury, and this fact tends to 
obscure the amount of curtailment of yield except in very severe cases. 
Although the disease occurs in all parts of the United States losses seem 
to be especially severe in Virginia, West Virginia, Tennessee, and south¬ 
ern Ohio of the eastern States, in Georgia and Louisiana of the south¬ 
ern States, and in California. In the commercial bean areas of the 
North it seemingly appears too late as a rule to cause much injury. It 
is occasionally severe in the New England States. In Virginia bean rust 
is one of the chief limiting factors in production. Severe injury is 
commonly found on three varieties, Kentucky Wonder, Navy Pea, and 
Tennessee Green Pod. Evidence of the severity of bean rust in Califor¬ 
nia and of the inefficacy of spraying may be seen in the following quo¬ 
tations. R. E. Smith (jo) in discussing the work at the California 
Experiment Station says: 
Mr. Rogers did a considerable amount of work during the year in an endeavor to 
find means for checking a serious rust ( Uromyces appendiculatus) which attacks the 
1 Published with the approval of the Director of the Virginia Agricultural Experiment Station. Paper 
56 from the Department of Plant Pathology and Bacteriology. 
2 Reference is made by number (italic) to “Literature cited, “ p. 404. 
Journal of Agricultural Research, Vol. XXI, No. 6 
Washington, D. C. June 15, 1921 
vc XeyNo. Va. (Blacksburg )-3 
(385) 
