692 
Journal of Agricultural Research 
VoLXXIV.NaS 
OCCURRENCE OE THE FUNGUS ON BAREEY 
Of the graminicolous species of Helminthosporium thriving in our 
northern latitudes, H. sativum shows, perhaps, the strongest omnivorous 
tendency, being vigorously parasitic on a number of grasses and occurring 
on others apparently in a manner more nearly suggesting a saprophytic 
relation. Its greatest luxuriance is attained, nevertheless, on the foliage 
of barley, from which it originally was described. According to the 
records of the Plant Disease Survey, the fungus has been reported on 
barley in 24 states, including all of the more important barley-growing 
sections of the country. Giissow {48) early recorded its occurrence on 
the same crop in Canada. 
Although the host is susceptible at any stage of development, the use 
of affected seed often resulting in the appearance of severe lesions in the 
basal portions of the young seedlings, the disease usually does not begin 
to show up in quantity until the plants are heading out. It is manifested 
by the appearance of spots varying from 0.5 to 3 mm. in width and from 
2 to 15 mm. in length, usually dark brown in the center and fading 
gradually at the margins into the green of the surrounding tissue. (PI. 17, 
B.) The lower leaf blades are first affected, the discolored areas multi¬ 
plying until scores of them may be present on one foliar organ and a 
considerable portion of the leaf tissue is involved (pi. 17, A). As a 
result the leaf soon withers and dies, the discolored areas fading slightly 
and becoming vaguer in outline, while the parts not visibly altered in 
appearance take on a grayish hue. The foliar spots never become 
bleached in the center as those caused by H, leersii on Leersia virginica; 
nor exhibit a reticulate pattern, like those induced by H. teres on barley; 
nor are they surrounded by a zone of leaf tissue from which the chloro¬ 
phyll has disappeared like those produced by H. bromi on Bromus inermis. 
At the same time the destruction of the lower leaves takes place, the 
disease makes progress in the younger foliage, which then succun^hs in 
the same way, until the uppermost leaf is affected. The effect of this 
virtual defoliation is to hasten the ripening processes. In a season 
favorable for the development of the disease, the grain may be ready for 
harvesting perhaps two weeks earlier than when the trouble is absent. 
As might be expected, the )deld is decreased in a measure approximately 
corresponding to the shortening of the growing period. 
Although the foliage of barley is most severely attacked the inflores¬ 
cence, as Pammel, King, and Bakke {104) pointed out, is not immune. 
The fungus may be found on the glumes and not infrequently on the 
seed. The diseased kernels usually are readily distinguished because of 
the dark-brown discoloration at the germ ends, a feature that has, 
indeed, been utilized by Atanasoff and Johnson (j) in selecting infected 
material for experiments on the dry-heat treatment. When such dis¬ 
colored kernels are placed in a germinator the fungus becomes visible 
usually within 24 hours as a dehcate white velvety outgrowth, that soon 
spreads on the filter paper or other material as an effused arachnoid myce¬ 
lium and produces, if the conditions are not too moist, an abundance of 
fructifications. A reduction in viability, usually apparent in slightly 
discolored seed, may become very considerable when the seed is more 
severely affected. After the basal sheath has been developed this organ 
often is attacked by the fungus and as a result takes on a yellow or light 
yellowish-brown discoloration. A considerable proportion of the rootlets 
