*54 
Journal of Agricultural Research 
Vol. XXVI, No. 4 
broom com, C. I. No. 243, was sprayed twice with water suspensions of 
culture I without producing any lesions. 
Feterita and Dwarf kafir were both sprayed with cultures I and V, and 
no lesions appeared. 
A Feterita-Milo hybrid was twice sprayed with culture I, without any 
evidence of infection in one experiment, but in the other, after three 
weeks, irregular reddish-brown streaks appeared on the margin and 
toward the center of one leaf blade. Although this plant was resprayed 
with the proso organism, no new lesions appeared and the original lesions 
did not spread. Typical colonies of the proso organism were not isolated 
from this plant and there was considerable doubt as to whether the infec¬ 
tion was due to this organism. 
Although no lesions appeared on inoculated plants other than proso, 
typical lesions always appeared on proso plants sprayed with isolations 
of the organism at the same time and kept in the same damp chambers. 
The only exceptions were the two cases mentioned above where the damp 
chambers failed to keep the plants moist. 
CULTURAL AND MORPHOLOGICAL CHARACTERS 
The organism producing the disease of proso described above is a short 
rod with rounded ends, arranged singly or in pairs. Occasionally chains 
occur. Two-day cultures on potato cylinders (stained with gentian violet) 
vary from 3.1/4 to 1.53/4 in length and 0.9/4 to 0.45/4 wide, with an average 
of 2.08/4 by 0.67/4. From two-day +15 agar cultures, stained with 
carbol fuchsin, they vary from 2.3/4 to 1.1/4 long by 0.9/4 to 0.5/4 wide, 
with an average of 1.23/4 by 0.67/4. In one-day cultures on potato 
cylinders stained with gentian violet, the range is 2.35/4 to 1.17/4 by 
0.9/4 to 0.45/4 with an average of 1.67/4 by 0.73/4. 
There are no spores, endospores, zoogloea, or pseudozoogloea. Cap¬ 
sules are present on beef peptone agar and other media, but do not stain 
readily with Ribbert's capsule stain or other stains (PL 4, G). 
Usually there is one polar flagellum, but occasionally there appear to 
be two or three. Flagella were stained with Casares Gil's stain (PL 
4 * H, I). 
At 33° C. cultures of the proso organism grown for nine days on beef- 
peptone agar and stained with carbol fuchsin show peculiar club-shaped 
growths with one end more or less enlarged and the other a short or long 
tail-like extension. These involution forms were observed only at high 
temperature (Pl. 4, F). 
Staining reactions. —All strains of the proso organism stain readily 
with carbol fuchsin and gentian violet but only lightly with methylene 
blue. There is definite polar staining (PL 4, I), especially with carbol 
fuchsin, which does not stain quite so heavily as gentian violet. The 
strains are Gram negative and not acid fast. 
Nutrient broth. —In +15 (Fuller's scale) beef-peptone bouillon there 
is moderate clouding in 24 hours and heavy in 48 hours. A thin pellicle 
forms over the surface which readily breaks up and falls in thin flakes. 
Often when broth cultures are a day old and the clouding is still light, a 
very thin pellicle forms and from this the clouding extends down into the 
tube in fine strands. Sometimes as cultures grow older the pellicle is 
heavier in the center, which hangs down into the broth. After about two 
months' time the inoculated tubes are a deeper color than the controls— 
a little darker than Ridgway's Buckthorn Brown. 
