July 15,1925 
Bean Varietal Tests for Disease Resistance 
153 
SUMMARY 
This paper presents a summary of four years’ bean varietal testing 
for resistance to anthracnose and bacterial blight. The results of 
preliminary greenhouse and field inoculations with bacterial wilt 
and notes on the natural occurrence of mosaic, obtained incidental to 
this study, are also included. 
A total of 663 varieties and strains of beans have been tested, of 
which 170 are American and 493 foreign, the latter being obtained 
from 23 countries. 
The data on relative susceptibility to bacterial blight are limited 
to field-plot inoculations which, in 1923, were replicated in three 
different localities. A large proportion of the foreign varieties were 
also subjected to carefully controlled greenhouse tests with the various 
biologic forms of the anthracnose fungus. Since some of the varieties 
were tested in the field only during years unfavorable for epidemic 
development of one or another of the diseases, the results on these 
are necessarily of a preliminary nature. 
Considering only those varieties on which there is fairly conclusive 
evidence, a total of 65 appear to possess decided resistance to anthrac¬ 
nose or bacterial blight, of which 5 are resistant to both diseases, 27 
to anthracnose alone, and 33 to bacterial blight alone. A few of the 
blight-resistant types may, however, prove to be also resistant to 
anthracnose if their apparent resistance in field tests is confirmed by 
greenhouse inoculations. 
Six of the 27 anthracnose-resistant varieties are practically immune 
to all known biologic forms of the fungus, as shown both by green¬ 
house and field inoculations. The remainder were affected only to 
a slight or very slight extent. 
No very high degree of resistance to bacterial blight was observed 
in any variety of Phaseolus vulgaris tested. Although additional 
comparative evidence is required, a number of the foreign varieties, 
however, appear to be somewhat more resistant than any of our 
American types. 
Very little is thus far known regarding the adaptability of the 
foreign varieties used in this study for direct commercial cultivation 
in the United States. Since some of the most resistant are late pole 
types of tropical or semitropical origin, it is inferred that these, at 
least, will be mainly valuable for hybridization with our susceptible 
American types. 
Tests conducted on a large collection of varieties of related species 
and genera of beans are briefly summarized. 
LITERATURE CITED 
(1) Barrtjs, M. F. 
1918. VARIETAL SUSCEPTIBILITY OF BEANS TO STRAINS OF COLLETOTRI- 
chum lindemuthianum (Sacc. & Magn.) B. & C. Phytopath¬ 
ology 8: 589-614, illus. 
(2) Burkholder, W. H. 
1923. THE GAMMA STRAIN OF COLLETOTRICHUM LINDEMUTHIANUM (SaCC. 
& Magn.) B. & C. Phytopathology 13: 316-323. 
(3) - 
1924. VARIETAL SUSCEPTIBILITY AMONG BEANS TO THE BACTERIAL BLIGHT. 
Phytopathology 14: 1-7. 
(4) Denaiffe, C. 
1906. les haricots. 493 p., illus. Paris. 
