May 26,1923 
Graminicolous Species of Helminthosporium 
663 
hyde treatments that have been devised against stripe, or the hot-air 
treatment described by Atanasoff and Johnson (j) against spotblotch. 
Moreover, as the plant is subject to attack at any stage of growth, and 
the fungus can spread from a small number of diseased seedlings to other 
plants, reduction of primary lesions by methods aiming at the disin¬ 
fection of the seed is of relatively less value than in the case of diseases, 
the occurrence of which is contingent on seed contamination and infection 
during the germination period. 
HBbMINTHOSPORIUM AVBNAE BIDAM 
Helminthosporium teres Sacc. forma avenae-sativae Briosi & Cavara 1889, in I fungi 
par. delle piante colt, od utili, no. 80. 
Helminthosporiumavenae-sativae (Br. &Cav.) LindaumRabenh. Krypt. FI. V. Deutsch¬ 
land. Bd. 2, Bd. I, Abt. 9, p. 34. 
Helminthosporium avenae (Br. & Cav.) Ravn, 1900, in Bot. Tidsskr. v. 23, p. 212-213. 
Helminthosporium gramineum of Ritzema Bos, Frank, Fraser not Rabenhorst. 
In 1889 Briosi and Cavara® distributed specimens of a fungus collected 
near Pavia, Italy, where it was found parasitic on the leaves of oats, 
Avena saliva L., producing narrow, oblong, longitudinally elongated, 
olivaceous foliar spots, with dark margins. The iiSection was described 
as starting ordinarily at the tip of the leaf, where the first spots appear, 
and from whence the mycelium gradually invades the leaf parenchyma, 
until the entire blade withers and dies. The injury to the foliage thus 
occasioned was reported to interfere with the full development of the 
seeds. Briosi and Cavara designated the fungus itself as Helmintho¬ 
sporium teres Sacc. forma avenae-sativae, differing from the typical species 
by the greater length of the conidiophores, the occurrence of the latter 
singly instead of in fascicles, and the somewhat smaller dimensions of 
its spores. In the brief diagnosis of the form, accompanied by figures, 
the conidiophores are described as scattered, stout, cylindrical, many- 
septate, fuliginous, measuring 150 to 200 by 9 to 12 /i; the spores as 
acrogenous, olivaceous, cylindrical, or slightly swollen in the middle, 
rounded at the ends, 4 to 6 septate, and measuring 80 to 110 by 15 to 16 ju- 
Their representation of the septa and spore wall as thick structures indi¬ 
cates that Briosi and Cavara used dead material for their studies, a cir¬ 
cumstance to which may be attributed, perhaps, the inexact description 
of the color of the spore, and their failure to mention the more distinctive 
features of the fungus. 
Eidam (35), in 1891, published an account of a leafspot of oats occur¬ 
ring in Silesia and affecting usually the first leaf, but sometimes also the 
second and third leaves of the host. He recognized the causal parasite 
as a new species, Helminthosporium avenae, distinct from his H, hordei 
(= /?. teres Sacc.) because of the negative results obtained in his attempts 
to infect barley with the former, and oats with the latter. Ritzema Bos 
{121) later described an attack upon oats by H, gramineum Rab., the 
resulting foliar spots differing from those occurring on barley in being 
short, somewhat round, and associated with a reddish color of the diseased 
leaves. Ravn (1x5), as the result of comparative cultural and biometri¬ 
cal studies of the parasites causing stripe, netblotch of barley, and the 
‘‘Helminthosporiosis'' of oats, concluded that the latter represents an 
independent species. 
It is of some slight nomenclatorial interest to note that Ravn, appar¬ 
ently in the belief that Briosi and Cavara's priority in recognizing the 
• op. dt., p. 657 
