Sept. 1,1924 
Bacterial Pustule of Soybean 
241 
gently between the thumb and fore¬ 
finger after spraying with the bacterial 
suspension. There were 23 Ito San and 
61 Mammoth Yellow soybean plants 
used in the experiment. The Ito San 
seed had been treated with formalde¬ 
hyde and germinated in a damp cham¬ 
ber, then planted in pots. The plants had 
developed the first pair of leaves when 
inoculated. The Mammoth Yellow 
seed was untreated and germinated in 
the soil. The cotyledons were just be¬ 
ginning to spread, showing a leaf shoot 
at the time of inoculation. 
The plants were kept moist in inocu¬ 
lating cages, bell jars, or paraffined bags 
for 28 hours after spraying with Bad. 
phaseoli EFS. On the rubbed leaves 
of the 11 infected Ito San seedlings 
were narrow brown streaks and pale 
green areas, from the former of which 
the parasite was reisolated. Twelve 
other Ito San seedlings and 32 Mam¬ 
moth Yellow seedlings were in the same 
inoculating cage, but no brown streaks 
appeared nor did they ever show any 
signs of infection. In this case it seems 
reasonable to conclude that the brown 
streaks were due to infection rather 
than to asphyxiation. 
Another method which proved suc¬ 
cessful was that of dipping the seed of 
Ito San soybean treated by the H 2 S0 4 
method, in a water suspension of the 
organism and germinating it in a 
damp chamber. The parasite was 
reisolated from a water-soaked cotyledon 
on one of these soybeans. For this type 
of inoculation Bad. phaseoli EFS. iso¬ 
lated from soybean was used. 
INOCULATION OF SOYBEAN AND 
LIMA BEAN WITH BACTERIUM 
PHASEOLI EFS. AFTER PASSAGE 
THROUGH SOYBEAN AND VEL¬ 
VET BEAN 
On the assumption that passage 
through soybean might increase the 
pathogenicity of Bad. phaseoli EFS. to 
soybean, spray inoculations were made 
upon seedlings of this plant and of Lima 
bean in inoculation cages. But pas¬ 
sage of Bad. phaseoli EFS. through 
soybean ( Glycine hispida) or Georgia 
velvet bean (Stizolobium) did not in¬ 
crease its virulence for soybean, nor, on 
the other hand, did passage through 
soybean decrease its pathogenicity to 
Lina bean, rs evidenced by the fact 
thrt, the worst cases of infection which 
the writer has ever seen were produced 
on King of the Garden and Fordhook 
Bush Lima sprayed in the hothouse in 
February with Bad. phaseoli EFS. 
isolated from inoculated soybean. The 
99182—25f-3 
high temperature maintained in this 
house, where the thermometer rarely 
fell below 75° F. during the night, and 
for days reached 103 to 110° in the 
middle of the day, was in a very large 
measure responsible for this. The dif¬ 
ference in the severity of the infection 
on the plants in this house and on 
plants of the same variety and age, 
inoculated at the same time with the 
same culture, but kept in a house with 
a temperature ranging from 64° to 72° 
F. the greater part of the time, was 
striking in the extreme. In the hotter 
house infection was much more abun¬ 
dant and progressed farther and much 
more rapidly. One of the worst infected 
plants collapsed entirely. The whole 
top was dead and the stem was with¬ 
ered and full of bacteria. The infection 
of the stem extended all the way down 
to the ground from the first pair of 
leaves, a distance of 6 inches. There 
were drops of yellow ooze from the 
stem when squeezed. These plants 
were inoculated when they had only 
the first pair of leaves. 
CULTURAL CHARACTERS 
In all cultural work on the soybean 
organism parallel tests were made 
with Bad. phaseoli EFS., but inasmuch 
as with a few exceptions no greater 
differences were found than might 
exist between two colonies of the same 
organism, the reader is referred to 
Smith’s published descriptions of the 
cultural characters of Bad. phaseoli 
EFS. (15, 16, 17, 20, p. 285-287) and 
space will be given here only to the 
differences found and to some additional 
facts not hitherto recorded. 
The best medium found for the soy¬ 
bean organism is fresh steamed potato 
cylinders. Bad. phaseoli sojense, like 
Bad. phaseoli EFS., makes a very 
copious growth on this medium, con¬ 
suming practically all the starch, and 
so filling the 2 cc. or more of water 
around the cylinders with slime that 
it becomes a solid yellow mass and 
does not flow when the tubes are 
turned upside down. The writer has 
never failed to obtain this character¬ 
istic growth if the potato cylinders 
were fresh, but even a slight drying 
out of the upper part of the cyl¬ 
inder may alter the character of the 
growth. 
Much of the cultural work was done 
before Ph determinations were made in 
this laboratory, and “approximately” 
after the P H reading means that the 
latter was worked out from the Fuller’s 
scale reading according to the formula 
of Quirk and Fawcett (12, p. 20). 
