230 
Journal of Agricultural Research 
Vol. XXIX, No. $ 
1921), Arkansas (diseased seed, 1919), 
Louisiana (1922), Kansas (1923, 1924), 
and Delaware (1924) only, but as Smith 
obtained it in 1902 from South Carolina, 
it is quite probable that some, at least, 
of the “bacterial leafspot” of soybean 
reported from time to time by various 
investigators has been due to the or¬ 
ganism herein described. 
This organism or Bad. glycine urn 
was present in South Dakota in 1922, 
but the material sent in was very dry 
and attempts at isolation of the para¬ 
site failed. 
SIGNS OF THE DISEASE 
The disease is characterized by an¬ 
gular reddish-brown spots on the leaves, 
varying in size from minute inconspicu¬ 
ous specks to large irregular brown 
areas involving a considerable portion 
of the leaf (PI. 1, A to G). The latter are 
caused by a fusion of the smaller spots 
and are not uniform in color, but mot¬ 
tled in appearance. The original small 
spots can usually be distinguished in 
these larger brown areas caused by 
their fusion. Portions of the large 
spots frequently drop out, leaving the 
leaf ragged. The browning sometimes 
follows the veins (PI. 2, B and C). 
A common and conspicuous, though 
not universal, sign of the disease is a 
pronounced yellowing. When present, 
it occurs as a yellow border around each 
individual spot or as a yellowed area 
thickly beset with tiny brown spots or 
inclosing larger brown areas formed by 
the expansion and fusion of the same 
(PI. 1, A to G). This yellow color 
varies from a pale yellowish green to 
a light cadmium (13). 
The first signs of the disease are very 
small, inconspicuous, pale green or some¬ 
times reddish-brown spots (PI. 1, D), 
usually slightly but distinctly elevated 
in the center. Sometimes the whole 
spot is elevated, making a minute pus¬ 
tule (PI. 1, F), sometimes only the central 
portion, which may be lighter colored 
than the pale yellowish-green periphery 
or may be reddish brown. These intu¬ 
mescences may be confined to either sur¬ 
face of the leaf or may extend through 
it and appear on both sides. They 
finally rupture the epidermis but rarely 
if ever attain a size of more than 1 mm. 
in diameter, and as the spot grows 
older they usually collapse, shrivel, or 
slough off. They are truly tumorlike 
to this extent, that they are due to 
both hypertrophy and hyperplasia (PI. 
3, A, C, D). At no stage is there a water- 
soaked appearance of the tissues such as is 
so striking in the early stages of the blight 
caused by Bad. glycineum Coerper. 
In August, 1923, at the experimental 
farm of the University of Wisconsin 
the writer observed on many varieties 
of soybeans a heavy infection of Bad . 
glycineum and confirmed a previous 
belief that when young infections are 
present the two diseases are easily dis¬ 
tinguishable, but at a later stage only 
the isolation of the parasite can insure 
a correct diagnosis. 
The writer has observed infection of 
the pods only once, viz, in some green¬ 
house experiments on the Hahto soy¬ 
bean, the pods of which are less hairy 
than those of the other varieties used 
up to that time; but in all probability 
it occurs frequently under favorable 
field conditions. The spots were brown 
and slightly raised and the organism 
was isolated therefrom. 
MICROSCOPIC APPEARANCE 
Microtome sections through the 
pustules on Hahto soybeans three 
weeks after inoculation show that the 
bacteria (stained with carbol fuchsin) 
EXPLANATORY LEGEND FOR PLATE 1 
Natural infections and greenhouse inoculations. All natural size except F. Paintings by Janies F. 
Brewer. 
A to I, Bad. phaseoli sojense Hedges: 
A—Natural infection on Mammoth Yellow soybean. Collected at Arlington, Va., October 7, 192L 
B.—Natural infection on Tarheel Black soybean. Collected at Arlington, Va., October 7, 1921. 
C — Natural infection on Barchet soybean. Collected at Arlington, Va., October 7, 1921. 
D. —Natural infection on Mammoth Yellow soybean. Very early stage which might easily be 
overlooked. Collected at Arlington, Va., October 7, 1921. 
E. —Artificial infection on Hahto soybean, inoculated March 11,1919. Painted April 3,1919; 3 week* 
old. Pustule stage. 
F. —Detail from Figure E showing pustule. X10 ca. 
G. —Artificial infection on Wilson Black soybean, inoculated March 12, 1920. Painted May 28, 
1920; 6 weeks old. 
II.—Bush string bean leaf sprayed with colony 6, October 20, 1919 (through bush string bean) Jan¬ 
uary 19, 1920. Painted February 9, 1920; 3 weeks old. 
I. —Bush string bean pod; inoculated March 1, 1920, with colony 6, October 20, 1919 (through bush 
string bean). Painted March 22, 1920; 3 weeks old. 
J to L, Baderium phaseoli EFS.: 
J. —Secondary infection on bush string bean pod on plant inoculated January 2, 1920 (in blossom 
at the time). Painted February 26, 1920. 
K. —Bush string bean leaf, inoculated January 2, 1920. Painted February 7, 1919, 5 weeks old. 
L—Bush string bean leaf, inoculated January 2, 1920. Painted February 7, 1919, 5 weeks old; 
showing only islands of green. 
