398 
Journal of Agricultural Research 
Vol. XXI, No. 6 
per cent in fertile infection which falls below 50 per cent in spore- 
producing capacity, while three varieties, White Marrow, Full Measure, 
and Keeney’s Rustless, rating below 50 per cent in fertile infection, have 
spore-producing capacities in excess of 50 per cent. In general it can be 
stated that the production of large sori is an indication of greater sus¬ 
ceptibility to infection than the production of small sori. 
Table VII .—Relative spore-producing capacity of the uredinia on different varieties 
Spore-producing 
capacity. 
Variety. 
Per cent. 
Number. 
IOO 
707 
Tennessee Green Pod, Navy Pea, Snowflake, Lady Washington, 
McCaslan, Virginia Cornfield, Dutch Case Knife, Powell’s 
Prolific, Creaseback, Cut Short, Golden Cluster. 
70 
49 1 
Pinto, White Marrow, Kentucky Wonder, Royal Corn. 
54 
380 
Pink, Red Valentine, Full Measure, Keeney’s Rustless. 
44 
3 i 4 
Tepary, Blue Pod Navy, Red Kidney, White Kidney, Horti¬ 
cultural Dwarf, Round Six Weeks, Longfellow, Low’s Champion, 
Brockton, Tennessee Wonder, Kentucky Wonder Wax. 
3 2 
227 
Early Refugee, Giant Stringless, Bountiful, Horticultural Pole. 
2 5 
177 
Warren, Bird Eye, French’s Horticultural, Black Valentine, 
Marblehead, Currie. 
16 
“3 
Yellow Eye, Burpee’s Strmgless, Mighty Nice, Mexican Red. 
11 
79 
Scarlet Wax, Crystal White, Dwarf Black. 
susceptibility of bean varieties under greenhouse con¬ 
ditions AS COMPARED WITH FIELD CONDITIONS 
The question is naturally raised in connection with greenhouse ex¬ 
periments as to what extent they serve as a reliable index of field be¬ 
havior. All the varieties of beans used in our greenhouse work have 
been grown in the field, most of them during two seasons, where they 
have been subjected to uniform exposure to rust infection by inoculation. 
The results of the first season’s field tests have been described in a pre¬ 
vious paper (4). In the 1918 tests the varieties were classified according 
to relative susceptibility in four groups, as follows: Susceptible, rust- 
enduring, rust-proof, rust-free. Yields were obtained only for the 
dwarf varieties commonly grown for dry-shell purposes and from the 
pole beans. In the 1919 tests some of the most susceptible varieties 
were eliminated and some additional varieties were added. This season 
was particularly favorable for the development of anthracnose, and 
some of the varieties suffered severe losses from this disease and to a 
lesser degree from bacterial blight. With respect to rust infection, the 
varieties respond in the same way during the two seasons, but the effects 
