Sept. 1 , 1924 
Bacterial Pustule of Soybean 
237 
BACT. PHASEOLI SOJENSE—Centinued 
Inoculation experiment showing the effect of previous passage through Phaseolus—Continued 
COLONY 3 (FROM SOYBEAN) 
COLONY 1 (FROM LIMA BEAN) 
5th week 
Lima bean (cage and bags): No noticeable 
increase in infection. The two worst in¬ 
fected leaves are much distorted but are 
neither yellowed nor shrivelled. 
Lima bean (cage and bags): Striking infection. 
A number of leaves have dropped off, wholly 
browned and shrivelled or with only a small 
amount of green tissue remaining, as some¬ 
times occurs in inoculations with Bact. 
phaseoli EFS. (PI. 1, L). Others have 
large brown shrivelled areas bordered with 
yellow, involving one-half to three-fourths 
of the leaflet. 
Dwarf bush string bean: Spots somewhat 
larger than at time of previous observation 
but there has been no very noticeable spread 
of the infection. 
Dwarf bush string bean: Conspicuous infec¬ 
tion. Typical brown and shrivelled spots, 
bordered with yellow. 
Soybean: Spots have increased considerably 
in size. 
Soybean: No signs of infection. 
8th week 
Lima bean: no secondary infections. 
Lima bean: Conspicuous infections in every 
respect like those caused by Bact. phaseoli 
EFS. 
Dwarf bush string bean: No increase of 
symptoms. Infection is much more re¬ 
stricted than on plants inoculated with 
colony 1. 
Dwarf bush string bean: Not distinguishable 
from infections caused by Bact. phaseoli 
EFS. 
Soybean: Spots enlarging somewhat. There 
has been good infection. 
Soybean: No infection. 
A repetition of the experiment with 
the same colonies corroborated the 
results set forth above. 
A third set of inoculations was made 
with another pair of colonies 6 but the 
temperature of the hothouse (about 
62° F.) was too low to favor infection. 
In the parallel sets of inoculations 
here described, passage through Phase¬ 
olus seemed not only to increase the 
pathogenicity to Phaseolus but to 
destroy it for soybean. However, in 
two previous experiments excellent 
infections had been obtained on soy-* 
bean by colony 1, August 6, 1917, 
through Lima (PL 1, E, F; PI. 2, B, D); 
and in two later experiments with colo¬ 
nies isolated from bush string bean 
some scattering but typical infections 
were obtained on soybean (PL 1, G). 
With one of these colonies 7 excellent 
infections were produced on bush string 
bean, dwarf wax bean and dwarf 
bountiful string bean. No infection 
was obtained on dwarf wax or Early 
Refugee wax bean with the other col¬ 
ony, 8 but wilt was caused on dwarf boun¬ 
tiful string bean. (Though primarily 
causing leafspot, both Bact. phaseoli 
sojense and Bad. phaseoli EFS. may 
produce wilt if the organism invades 
the vascular system.) 
In conclusion, however, it may be 
said that in no case has the writer found 
the same colony of Bact. phaseoli sojense 
equally infectious to soybean and Lima 
or bush string bean. 
6 From Texas soybean: Colony e, Sept. 23, 1916>soybean>Lima pod>soybean> 
sovhpan^ 1 soybean>colony 5 
soy Dean > j bush string bean > colony 12. 
7 From Texas soybean: Colony e, Sept. 23, 1916,>soybean>Lima pod>soybean>soybean>Lima> 
bush string bean>colony 6, Oct. 20, 1919. 
8 From Texas soybean: Colony e, Sept. 23, 1916>soybean>Lima>bean pod>soybean>soybean>bush 
string bean>colony 11, Dec. 5, 1919. 
EXPLANATORY LEGEND FOR PLATE 4 
Inoculations on Phaseolus with Bacterium phaseoli sojense (through soybean), Bacterium phaseoli sojense 
(through Lima bean),,and Bacterium phaseoli EFS. for comparison. (Photographs by James F. Brewer.) 
A and B.—Comparative effect on bush string bean of Bacterium phaseoli sojense four weeks after inoculation 
with (A) organism through soybean; small spots; (B) organism through Lima bean: leaf shriveled 
XIM. 
C and D.—Comparative virulence to Lima of (C) Bacterium phaseoli sojense through soybean and (D) 
Bacterium phaseoli EFS. 18-day-old infections. XL C, tiny spots, no water soaking. D, excellent 
typical infection. 
E to G.—Comparative effect on Lima pods of (E-F) Bacterium phaseoli sojense through soybean and (G) 
Bacterium phaseoli EFS. E, 3-weeks-old infection. XL F, detail from E. X5 ca. G, 7-day-old 
infection. XL 
H.— Bacterium phaseoli EFS. 11-day-old infection on Lima bean leaf, water soaking. X5. 
