Sept. 1 , 1921 
Bacterial Pustule of Soybean 
239 
BACTERIUM PHASEOLI SOJENSE 
(THROUGH SOYBEAN) 
BACTERIUM PHASEOLI EFS. 
8th day. 
Soybean seedlings: pale green spots, pustules. 
Large plants: no signs of infection. 
Lima: No signs of infection. 
Soybean seedlings: No signs of infection. 
Lima: Excellent infections on all plants. On 
some of the younger leaves there is scarcely 
any sound tissue and the leaves are dis¬ 
torted. The leaves have a pale green mottled 
appearance on the surface and are a mass of 
water-soaked spots underneath. 
llth day. 
Soybean: No noticeable change. Both col¬ 
onies infectious. 
Lima : No signs of infection. 
Soybean seedlings: No signs of infection. 
Lima: Worst infected leaves are rapidly shrivel¬ 
ling. Spots brown and surrounding tissue is 
turning yellow. 
13th day. 
Soybean seedlings: Spots larger and consider¬ 
ably more conspicuous. Larger plants: No 
signs of infection. 
Lima: No signs of infection. 
Soybean seedlings: No signs of infection. 
Lima: Bacterial ooze on the infected leaves. 
The flowering has been much retarded, buds 
still very tiny while checks are in full flower. 
Brown spots coming on stems of all plants. 
16th day. 
Soybean: No infection on older plants. 
Lima: No signs of infection. 
Soybean seedlings: No infection. 
Lima: Distortion of many of the younger dis¬ 
eased leaves where enough contiguous sound 
tissue was left to continue to grow normally 
while the diseased area could not. Many 
yellowed leaves. Many leaves dropping off. 
18th day. 
Soybean: No infection on older plants. 
Lima: No signs of infection. 
Soybean: No signs of infection. 
Lima: In some of the leaves practically all the 
chlorophyll is gone—only isolated patches of 
green. The rest of the leaf is yellow, not 
brown or shrivelled or dry. 
19th day . 
Soybean: No infection on older plants. 
Lima: No signs of infection. 
Soybean: No infection. 
Lima: Excellent stem infections—external 
brown spots filled with bacteria. Flower 
buds not opening. Many buds falling off. 
5th week. 
Soybean: Infection on older plants also. 
Lima: A few infections. These are like 
typical Bad. phaseoli EFS. infections. 1 
Multitudes of bacteria. 
Soybean seedlings: No infection. 
6th week. 
Lima: Many water-soaked spots on some of j 
the leaves. This water-soaking is less f 
noticeable to the naked eye than that in j 
young spots on Lima produced by Bad. 
phaseoli EFS. Slight elevation'of the epi¬ 
dermis but no real pustules. 
Soybean seedlings: No infection. 
7th week. 
Soybean photographed (PI. 2, C). 
Iii both these sets of comparative 
inoculations with Bad. phaseoli sojense 
(through soybean) and Bad. phaseoli 
EFS. the difference in virulence for 
Lima bean was very striking through¬ 
out the experiments. 
INFECTION PRODUCED ON SOYBEAN 
SEEDLINGS BY BACTERIUM PHAS¬ 
EOLI EFS. 
The first very successful infections 
on soybeans with Bad. phaseoli EFS. 
were obtained on the cotyledons of Ito 
San soybeans germinated and inocu¬ 
lated in a sterile Petri dish damp 
Later comparative inoculations on 
Lima bean in which younger plants 
were inoculated with the two organ¬ 
isms produced similar results (PL 4, 
C, D). Infection with the soybean 
organism (through soybean) took place 
very slowly. The water-soaking was 
usually absent or much less con¬ 
spicuous than in infections with Bad. 
phaseoli EFS. and sometimes the only 
signs of infection for weeks were tiny 
pale green spots with or without red 
centers. Usually, however, a few spots 
resembling typical Bad. phaseoli EFS. 
infections appeared weeks after inocu¬ 
lation. 
