394 Journal of Agricultural Research voi. xxi, n 0 . 6 
The varieties are grouped for convenience according to the dwarf or 
running habit and the color of the pod. Of the 46 varieties of dwarf 
or bush beans, 32 have green pods and 14 wax pods. Of the 18 varieties 
of pole beans, 13 have green pods and 5 wax pods. 
The very marked variation in the susceptibility of the different varie¬ 
ties under the conditions of the experiments is evident. They are 
arranged in the different groups according to susceptibility to infection, 
the production of sori (percentage of fertile infection) being used as the 
basis for comparison in those varieties which produce sori rather than the 
percentage of total infection. 
In Table IV the 64 varieties are grouped under the four classes, and 
the comparative susceptibility of the classes as a whole is shown. It is 
apparent that pole beans with green pods constitute the most susceptible 
class and bush beans with wax pods the least susceptible, that pole 
beans are more susceptible as a class than bush beans, and that green-pod 
varieties are more susceptible than wax-pod varieties. 
Considering that the production of sori is an indication of greater 
susceptibility than the production of flecks, it is seen that 67 per cent 
(12 in 18) of the pole varieties produced sori unaccompanied by flecks 
as compared with 35 per cent (16 in 46) of the bush beans, while only 11 
per cent of the former class produced flecks unaccompanied by sori as 
compared with 33 per cent of the latter class. Comparing green-pod 
varieties with wax-pod varieties, the percentage with sori only is 58 as 
against 11, and for flecks only the percentage is 11 as against 63. Com¬ 
paring severity of infection on individual varieties, it is seen that the 
fertile infection was 50 per cent or more of the standard in 55 per cent 
of the pole varieties as against 15 per cent of the bush varieties, and in 
33 per cent of the green pods as against 11 per cent of the wax pods. 
Table IV .—Susceptibility of different classes of bean varieties to rust 
Bush. 
Pole. 
Green. 
Wax. 
Green. 
Wax. 
Number of varieties tested. 
IA 
13 
IO 
■2 
5 
2 
Number bearing sori only. 
l6 
Ai + 
Number bearing sori and flecks. 
II 
A 
Number bearing flecks only. 
5 
IO 
O 
2 
Number showing no infection. 
1 
Number showing fertile infection 50 per cent or 
more of standard.. 
7 
8 
2 
CORRELATION BETWEEN SEED CHARACTERS AND SUSCEPTIBILITY TO 
RUST 
In order to determine whether susceptibility to rust is associated with 
any particular color pattern or shape of the seed, a study of the seed 
