238 
Journal of Agricultural Research 
Vol. XXIX, No. 0 
It is to be noted that the infection on 
all the varieties of Phased us inoculated 
with Bad. phaseoli sojense resembled 
that produced by Bad. phaseoli EFS. 
and in the best cases was not to be 
distinguished from it. There was even 
reddening of the veins in infected dwarf 
bountiful string bean, but in no case 
were pustules produced. Wilt was occa¬ 
sionally observed in infections on 
Phaseolus. Microscopic examination 
of the petiole of a wilted bush string 
bean leaf showed that the bacteria 
were present in the vessels but not con¬ 
fined to them. 
COMPARATIVE INOCULATIONS ON 
BEANS AND SOYBEANS WITH 
BACTERIUM PHASEOLI EFS. AND 
BACTERIUM PHASEOLI SOJENSE 
(through soybean) 
Not only is Bad. phaseoli EFS. much 
more infectious to Phaseolus than the 
soybean organism, but thus far, with 
the exception of a single experiment, it 
has been entirely nonpathogenic to soy¬ 
bean seedlings or older plants, when 
inoculations have been made by any of 
the methods so successful in producing 
infection on Phaseolus with Bad. 
phaseoli EFS. or soybean by inocula¬ 
tion with Bad. phaseoli sojense. In¬ 
fection was obtained when a modifica¬ 
tion of these methods was employed, 
that is, when the leaves were rubbed 
gently between thumb and forefinger 
after spraying. In addition to spray¬ 
ing and pricking inoculations in 
inoculation cages, an attempt was 
made to produce the disease by so 
placing healthy young soybeans among 
very badly diseased Lima beans that 
their leaves would come in contact 
with the bacterial ooze from the leaves 
of the latter, and by watering the 
plants in such a way that the bacteria 
would be washed down upon the soy¬ 
beans. With the single exception 
noted above, all of these inoculations 
failed. There were 24 of these experi¬ 
ments, made in every month except 
May and November. 
The history of the exceptional inocu¬ 
lation experiment is as follows: Eight 
pots of Mammoth Yellow soybean seed¬ 
lings grown from seeds treated with 
concentrated H 2 S0 4 and planted Sep¬ 
tember 15, 1920, were sprayed at 4 
p. m. October 4 with a 2-day-old culture 
of what proved later to be a very viru¬ 
lent colony of Bad. phaseoli EFS. (col¬ 
ony 6, August 24, 1920, isolated from 
string bean leaves). The seedlings 
ranged in size from those just appearing 
above the ground to plants 8 or 9 
inches high. Some were pricked as 
well as sprayed. The plants were 
sprayed again the following day at 10 
a. m. and 4 p. m. and were kept in a 
moist atmosphere for 45 hours. On 
October 15, 11 days after inoculation, 
there were a few scattering brown spots, 
some of them marginal. These were 
not associated with the pricks. There 
were no pustules and the spots did not 
resemble infection by Bad. phaseoli 
sojense nor did microscopic examina¬ 
tion reveal the presence of bacteria. 
Plates were poured, however, and Bad. 
phaseoli EFS. isolated, but although 
the plates were inoculated very heavily 
only seven colonies appeared. Two of 
these showed the radiating lines, and 
two the internal concentric striae both 
illustrated in Plate 7, B and J. In 
other spots examined later a few scat¬ 
tering bacteria were found. The 
browning may have been partly due to 
asphyxiation; yet in both this experi¬ 
ment and in some described later 
Bad. phaseoli EFS. was plated from 
the browned areas. 
This very slight evidence of the 
pathogenicity Of Bad. phaseoli EFS. 
for soybean^ led to some experiments 
which resulted in very good infections 
on soybean, but the conditions were 
quite abnormal. The inoculation ex¬ 
periment described below gives a 
fair idea of the typical differences 
usually found between Bad. phaseoli 
sojense and Bad. phaseoli EFS. in their 
pathogenicity to Lima bean and soybean: 
, Three rapidly growing Lima bean 
plants (Burpee’s Fordhook Lima) just 
beginning to put forth tiny flower buds 
and two Hahto soybean seedlings 8 to 
12 inches high were inoculated June 5, 
1919, by spraying with Bad. phaseoli 
EFS. In other experiments many more 
soybeans were inoculated, but with the 
same results. For comparison eight 
large Hahto soybeans and two seedlings 
of the same variety about 8 inches high, 
also one Lima bean plant with several 
pods and blossoms, were inoculated 
with the soybean organism (from 
soybean). In other experiments more 
Lima beans were used, but with the 
same results. Two colonies of each 
organism were used, and both sets of 
plants were put into inoculation cages 
and kept in a very hot, moist atmos¬ 
phere for two days. The results were 
as follows: 
