Journal of Agricultural Research 
Vol. XXI, No. 6 
402 
throughout the season. The inj ury from rust was not so great as in 1918, 
apparently on account of seasonal differences; and the plants in the 
rusted plot retained their leaves longer and matured a fair crop. The 
yields are shown in Table X. The figures are in grams of shelled beans 
for single rows 60 feet in length and are averages of two rows for each 
variety. It will be noted that the three susceptible varieties all show a 
decrease in yield on the inoculated plot, while the three resistant varieties 
show an increase. It seems from this that the soil of the inoculated plot 
was better and that greater differences in the yield of the rusted and 
rust-free rows of susceptible varieties would be expected on plots of equal 
fertility. The three susceptible varieties show an average decrease of 
28 per cent in the inoculated plot, while the three resistant varieties show 
an average increase of 31 per cent. It seems apparent that a reduction 
in yield of 50 per cent or more may be expected from a severe rust attack 
on susceptible varieties. 
Table X. Yields of rust-susceptible and resistant varieties of beans in rusted and rust- 
free plots 
Variety. 
Susceptibility 
to rust. 
Rust-free 
plot . 1 
Rusted 
plot . 1 
Yield of 
rusted plot 
iti percent¬ 
age of rust- 
free plot. 
Tennessee Green Pod 
Pinto.______ 
Navy Pea. 
Bird Eye.. 
Yellow Eye. 
Red Kidney. 
Susceptible. . 
....do. 
....do . 
Resistant. 
_do. 
....do. 
97o 53o 
385 217 
1,007 959 
2, 243 
2 > 3 2 5 
1,466 2,091 
2,162 3,256 
55 
56 
95 
104 
i43 
151 
1 Expressed in grams per 6 o-foot row. 
BIOLOGIC FORMS OF BEAN RUST 
We have made no extended study of the occurrence of biologic forms 
of the bean-rust fungus, but it seems desirable to record such observations 
as have been made in connection with the studies on susceptibility of 
varieties. 
The strain of rust from the kidney or garden bean which we have 
used in our studies has been tested on a large number of horticultural 
varieties of the kidney bean ( Phaseolus vulgaris), on 9 varieties of the 
lima bean, (P. lunatus L.), 1 variety of the tepary bean (P. acutifoliuslatifo- 
linsD. F. F reeman), 18 varieties of cowpeas (Vigna sinensis (L.) Fndl.), 1 va¬ 
riety of the broad or horse bean ( Vicia jaba), and 1 variety of asparagus bean 
(Dolichos sesquipedalis L.). Infection has resulted on many varieties of 
the kidney bean, as recorded previously, and also on the tepary bean. 
Slight infection only was obtained on 1 variety of lima bean in the green¬ 
house, but the other 8 varieties tested remained freefrominfection in both 
greenhouse and field. The infection in this case was slight and con- 
