628 
Journal of Agricultural Research 
Vol. XI, No. w 
elude, therefore, that the bladeblight of oats as described by Manns is 
different from the bacterial-blight of barley treated in this paper. 
While Manns (4, p . 104) supposes that barley is attacked by his blade- 
blight of oats, this is regarded by the writers as doubtful. He states 
that: 
Among the barleys grown at the Station, one variety, known as Primus, showed a 
susceptibility to the disease even more marked than did the Wideawake variety 
among the oats. The Oderbrucker variety of barley also showed an occasional blade 
infected. These observations were verified by cultures. 
In this statement it is possible that Manns refers to the same bacterial- 
blight which is now under consideration, since the present writers have 
observed this blight on both the Primus and Oderbrucker barleys. And, 
furthermore, his statement that “observations were verified by cultures” 
does not seem to imply any carefully conducted cross-inoculation 
experiments. 
DEVELOPMENT OF THE DISEASE 
The disease will not ordinarily have blighted enough leaves to attract 
attention until the plants are two-thirds grown. The earlier stages of its 
development were, however, followed with care in the experimental fields 
in 1915 and 1916. In 1915 it was first detected in a field of Beldi barley, a 
common six-row variety. The seed of this was from a crop badly infected 
in 1914 and saved for this trial planting. A good, vigorous stand was 
secured, and the plants were 8 to 10 inches high before the first lesions 
were observed. These were well scattered over the field, and doubtless 
a few earlier primary lesions had been overlooked, since no trouble has 
been met in infecting younger plants in the experimental inoculations. 
From this time on the disease made steady progress, and two weeks 
later from 2 to 5 per cent of the plants showed dead, blighted leaves, 
so that even a casual observer would notice it. In 1916 earlier lesions 
were noted, but the subsequent development was very similar to that in 
1915. This probably represents extreme developments in Wisconsin, 
but, as will be explained later, the disease is capable of producing greater 
injury under certain conditions. 
OCCURRENCE AND HOST RANGE 
GEOGRAPHICAL DISTRIBUTION 
The bacterial-blight of barley has been noted and specimens collected 
by one of the writers (A. G. Johnson) in eight different States as follows: 
Akron and Greeley, Colo.; Ames, Iowa; St. Paul, Minn.; Amsterdam, 
Bozeman, and Moccasin, Mont.; Williston, N. Dak.; Corvallis, Oreg. 
Aberdeen, Brookings, and Highmore, S. Dak.; Janesville and Madison, 
Wis. If the reference to the disease by Manns (4, p. 104) from Wooster, 
Ohio, is included, the bacterial-blight of barley has been found in nine 
States. This distribution is indicated in figure 1. 
