July, 15 1925 
Bean Varietal Tests for Disease Resistance 
147 
Table III .—Detailed results of greenhouse inoculations with a combined spore sus¬ 
pension of all known biologic forms of Colletotrichum lindemuthianum on some 
of the more resistant varieties and on certain others concerning which the infor¬ 
mation in Table II is incomplete or lacking —Continued 
© 
& 
Number of plants showing the extent 
of infection indicated 
s 
§ 
>> 
.2 
o3 
> 
Name or seed charac¬ 
teristics 
Source 
Very severe 
Severe 
Moderate 
Slight 
Very slight 
© 
a 
o 
fc 
Remarks 
603 
Finely stippled lavender 
Urundi_ 
3 
23 
Immune except 
for small per- 
centage of 
slightly suscep¬ 
tible sports. 
Apparently very 
resistant. 
Immune. 
Very susceptible. 
Immune except 
for small per¬ 
centage of sus¬ 
ceptible sports. 
Immune. 
607 
kidney beans with 
olive-green stripes. 
Long, finely stippled 
blue-tan beans with 
black stripes. 
Small, lavender mottled 
_do. 
7 
619 
_do. 
25 
625 
beans with dark ring 
around hilum. 
Long, reddish-lavender 
_do. 
18 
9 
631 
mottled beans with 
dark ring around hilum. 
Small, flat, yellowish-tan 
mottled beans. 
Short, thick purple-choc¬ 
olate colored beans. 
Small, flat pink beans_ 
.do.. 
3 
13 
633 
_do_ 
57 
635 
_do_ 
6 
4 
Very susceptible. 
Resistant except 
for a fair per¬ 
centage of sus¬ 
ceptible sports. 
639 
Small, flat dark-tan beans. 
_do_ 
2 
4 
5 
8 
18 
The reaction of a number of the varieties listed in Table III shows, 
as expected, that the conditions for infection in the field plot of 1923 
were not uniformly favorable enough to reveal the differences in 
susceptibility brought out by this severe greenhouse test. The same 
phenomenon has been repeatedly noted by Barrus ( 1) and others 
m comparisons of greenhouse and field inoculations with anthracnose. 
It seems to prove that field conditions are rarely as severe as the 
artificial greenhouse combination, and that varieties which are 
seldom more than slightly infected under commercial cultivation 
may develop the disease to a moderate or even a severe extent in the 
greenhouse. 
The 12 varieties and strains used as controls in this experiment 
were, with one exception, all severely or very severely infected; the 
exception (WelTs Red Kidney) showed infection only to a moderate 
extent. 
In this test 12 varieties proved to be practically immune to all the 
11 cultures or biologic forms of Colletotrichum lindemuthianum , e. g., 
Nos. 115, 413, 455, 551, 552, 594, 597, 603, 6p7, 619, 631, and 633. 
However, comparisons of their reaction in earlier greenhouse inocula¬ 
tions and field tests (Table II, columns 6 to 8) show that all but No. 633 
are listed in one column or another as very slightly infected. This 
apparently contradictory evidence is probably due as much to 
variation in judgment of the observer as to real variation in the 
extent of infection. While the definitions of immunity (i. e., no 
infection) and “very slight” infection, in Table I, would seem to 
