May 26, 1933 
Graminicolous Species of Helminthosporiuni 
697 
tion of the parasite, the figures of the sporophore and conidia show an 
unmistakable resemblance to those of H, sativum developing in artificial 
culture or on natural substrata under moist conditions. 
Another reference to the relation of an unidentified species of Helmin- 
thosporium to root rot of wheat is given by Raeder (JJ^) who observed 
considerable damage caused by this trouble in Idaho. His description 
of the symptoms—stunting of the heads, shriveling of the grains, dis¬ 
coloration of the sheath at the base, and occasionally also of the lower 
nodes—certainly suggest the spotblotch fungus. Snowden's {135) report 
of H. sorokinianum on wheat in Uganda may plausibly be interpreted 
as referring to the same parasite. 
The accounts briefly summarized in the preceding paragraphs con¬ 
cerning the occurrence of a species of Helminthosporium on wheat in 
association with well-defined lesions raise the questions as to whether 
one or several congeneric forms are concerned. The writer has examined 
scores of strains of Helminthosporium isolated from black-pointed 
wheat seeds (PI. 18, Aa-Cb), from discolored portions of the stems 
and leaves of both young (PI. 18, E) and more mature wheat plants, 
and from conidial fructifications occurring on the glumes of wheat 
heads (PI. 18, D). Although the material was obtained from a consider¬ 
able number of localities in the middle western section of the United 
States, no constant morphological differences such as distinguish the 
different species discussed in this paper, could be detected between the 
various strains. Nor was it possible to recognize any significant differ¬ 
ences between the forms isolated from wheat and various strains of 
H. sativum isolated from barley leaves heavily affected by spot blotch. 
In some preliminary cross inoculation experiments undertaken by the 
writer, barley and wheat seedlings proved equally susceptible to attack 
by strains derived from the same and from the reciprocal host; and the 
lesions produced were indistinguishable regardless of the source of the 
inoculum. Such identity of morphological and physiological charac¬ 
teristics, altogether in harmony with the findings of L. J. Stakman (i 38) 
and of McKinney (^7) have convinced the writer that for the most part 
a single species of Helminthosporium, namely, H. sativum^ is involved in 
the widespread infection of wheat manifested variously by such symp¬ 
toms as stunting of growth, seedling blight, basal browning, root rot, 
foot rot, node decay, leaf spot, stem discoloration, and black point. 
And as the reports of Sorokin, L. J. Stakman, and Bassi indicate, the 
same fungus evidently is associated with similar pathological conditions 
in rye. 
In another connection, it is true, attention has been called to the fact 
that the type of injury occasioned by Helminthosporium sativum on the 
wheat plant is duplicated by the attack of several congeneric species on 
other hosts, as, for example, H. vagans on Poa pratensis and H. monoceras 
on Echinochloa crus-galli. The occurrence of one or more species of Hel¬ 
minthosporium other than H. sativum^ associated with similar lesions is 
consequently not to be excluded as a possibility. Nevertheless, there 
seems to be little reason to believe that H, gramineum has ever been 
found parasitic on wheat in spite of the papers of E. C. Johnson, Palm, and 
Bassi, indicating such parasitic relation. The reports of Johnson and 
of Palm, as has been pointed out, appear to have been based on obviously 
erroneous identification of the fungus concerned. And the form of dis¬ 
ease described by Bassi corresponds so well to the trouble investigated 
by L. J. Stakman that it is hardly probable that two separate species 
