158 
Journal of Agricultural Research 
Vol. XXVI, No. 4 
isolated and successful pure culture inoculations made by spraying plants 
with water suspensions of the organism. Organisms obtained from 
leaf spots on sorghum produced the characteristic lesions on broom corn. 
Lesions on broom corn are illustrated in the first volume of Smith's 
Bacteria in Relation to Plant Diseases (5, pi. 20). In Volume II (< 5 , 
p. 63-64) Doctor Smith shows cross sections of leaves illustrating stom- 
atal infection. In a footnote he gives the organism the name Bacterium 
andropogoniy with a brief characterization (6, p. 63). 
In both diseases on broom corn and sorghum the lesions are described 
as red blotches of varying size and shape. The reddening is, of course, 
a host reaction which can also be produced by mechanical or other 
injury. Proso plants do not react in this way. Reddening does not 
follow bacterial invasion or other injury, and consequently bacterial 
lesions are not red but water-soaked and brown. Realizing that it 
might be possible for one organism to infect plants of closely related 
genera and produce a different host reaction in each, these diseases of 
sorghum and broom com were kept in mind while working with the 
proso organism. Cultures of Bacillus sorghi and Bacterium andropogoni 
were not available for cross inoculations, and unsuccessful attempts were 
made to infect various kinds of sorghum and broom com with the proso 
organism as described above. Twelve inoculations on sorghum, broom 
com, and related plants produced no lesions, while proso plants inocu¬ 
lated at the same time and kept under the same conditions developed 
typical lesions. 
A comparison of the cultural and morphological characters of these 
three organisms brings out important differences. The fact that BurrilTs 
organism was a bacillus precludes further comparison with the polar 
flagellate organism infecting proso. It produces spores and does not 
liquefy gelatin, while the proso organism does not produce spores and 
liquefies gelatin slowly. 
Bacterium andropogoniy E. F. Smith, and the proso organism are both 
polar flagellate, white, slow-growing organisms producing no spores, 
bluing litmus milk, producing no indol. They differ, however, in impor¬ 
tant cultural characteristics. Bacterium andropogoni is sticky on agar 
and hard to remove, while the proso organism is butyrous. Bacterium 
andropogoni does not liquefy gelatin and does not reduce nitrates. The 
proso organism liquefies gelatin slowly and reduces nitrates promptly. 
These cultural differences, combined with the lack of infection on sorghum 
and broom com with the proso organism, lead to the conclusion that the 
two organisms and diseases are distinct. 
DISSEMINATION OF PROSO ORGANISM 
During the growing seasons of 1921 and 1922 seed of Early Fortune, 
was sown at Tuxedo, Md., on ground which had not, as far as known, 
ever been sown to proso, certainly not for several years. In 1921 the 
seed was sown late and the season was dry. Only scattered lesions of the 
bacterial disease appeared on the leaves and peduncles of the plants. 
Isolations were made, however, which produced the disease on green¬ 
house plants during the winter. The seed from this plot was planted in 
1922 on ground about 200 feet from the 1921 plot. For several weeks 
after planting there was a great deal of rainy weather, and temperatures 
and humidity were high. When the plants were about half grown there 
was 100 per cent infection and about 10 per cent of the plants had been 
