July 15, 1925 
Bean Varietal Tests for Disease Resistance 
103 
and Magn., B. and C.), which are doubtless the two most important 
diseases of beans in the eastern United States. Incidental to tests 
with these diseases, notes were made on the natural occurrence and 
severity of mosaic. The work in 1923 also included greenhouse 
and field inoculations with bacterial wilt {Bacterium jiaccumfaciens 
Hedges), a disease until recently confused with bacterial blight, and 
of increasing economic importance in the northern bean sections. 
Authentic virile cultures of the bacterial blight and wilt organisms 
were obtained from Florence Hedges, of the Laboratory of Plant 
Pathology of the Bureau of Plant Industry, United States Depart¬ 
ment of Agriculture, and by isolations from typically diseased plants 
from Micmgan and New York. Tested cultures of the alpha, beta, 
and gamma biologic forms of the anthracnose fungus were obtained 
from W. H. Burkholder, of Cornell University; and the eight biologic’ 
forms (Nos. I to VIII, inclusive), as well as samples of the bean varie¬ 
ties and strains used to differentiate them, were kindly furnished by 
J. G. Leach, of the University of Minnesota. The alpha and beta 
forms only were used in the inoculations of 1920 to 1922, inclusive,; 
while in 1923 there were added the gamma form described by Burk¬ 
holder {2) and also the above-mentioned eight biologic forms recently 
described by Leach (<§). Since some of the varieties listed in Table II 
were not tested in 1923, they were presumably exposed only to the 
first two forms, a possibility which should be remembered in judging 
their behavior. Although some separate greenhouse inoculations 
are recorded in this paper for certain of the forms,,no detailed study 
to determine resistance or susceptibility to individual biologic forms 
has been made. The object has been to find, if possible, suitable 
types immediately available for the plant breeder, which combine 
resistance or immunity to all the forms. The whole subject of biologic 
forms in the bean Colletotrichum requires further investigation and,, 
at least until the relationships between the 11 forms thus far reported 
are established, extensive variety testing with individual forms is 
scarcely advisable. 
LOCATION, DURATION OF TESTS, AND METHODS EMPLOYED 
FIELD STUDIES 
The field investigations here reported extend over the period 1920 
to 1923, inclusive. In 1920 a single test plot was located near Sagi¬ 
naw, Mich., in cooperation with the local farm bureau. During the 
succeeding years the work was centered at East Lansing, Mich., 
where land, laboratory facilities, and much assistance were furnished 
by the departments of botany and farm crops of the Michigan Agri¬ 
cultural College. 4 Since weather conditions frequently prohibit the 
best development of anthracnose at Lansing, it was necessary, in 
order to obtain a severe test of the varieties every season, to establish 
additional plots containing partial replications of the Lansing test 
in more favorable places. Accordingly in 1921 and 1923 a plot was. 
maintained in the northern peninsula of Michigan near McMillan in 
cooperation with the Jerome B. Rice Seed Co. In 1923, one was. 
placed in the northern “Thumb” section of Michigan near Bad Axe r 
m cooperation with the local farm bureau, and another at St. Paul,, 
* Credit is due G A. Meckstroth for assistance at Saginaw during 1920, and to E. F. Hopkins* E. V. 
McKenna, and Zadik Voscan for handling the details of the work at East Lansing in 1923. 
