May 36, X923 
Graminicoloils Species of Helminthosporium 
675 
maintain. The ascigerous stage, it must be admitted, is morphologically 
not readily distinguished from related congeneric forms. The fungus, 
in any case, would seem to be referable to Pyrenophora rather than to 
Pleospora, if, indeed, the former is to be maintained as a separate genus. 
HELMINTHOSPORIUM GIGANTEUM H. & W. 
Heald and Wolf, in 1911, described {34) and later also (55) figured a 
species of Helminthosporium on Bermuda grass (Cynodon dactylon L. = 
Capriola dactylon [L.] Kuntze) collected at Falfurrias, Tex., where it 
was found associated with a disease— 
characterized by the presence of numerous yellowish or pale straw-colored spots, 0.5 
to I mm. wide, by i to 4 mm. long, longitudinally elongated, and with a narrow brown 
border. The spots are generally absent from the leaf sheath, and when numerous they 
may become confluent on the lamina and thus cause somewhat extended dead areas. 
The fungus, which was named quite appropriately Helminthosporium 
giganteum, was further characterized as follows: 
The conidiophores are dark brown, many-septate, 9 to 12 by 200 to 400 /i, with a 
slightly bulbous base; the spores are elongated, cylindrical with slightly tapering 
ends, 5-septate, pale brown, densely granular contents, 15 to 21 by 300 to 315 fi 
The writer collected the same parasite on Bermuda grass at various 
times during the months of February, March, and April, 1921, near Fort 
Myers and Wauchula, Fla. During February and March, especially in 
the vicinity of Fort Myers, the fungus occurred in considerable abundance, 
old spots bearing sporophores being foimd scattered generally over the 
foliage of the host. Fresh lesions providing material suitable for study 
were almost entirely absent at that time, a circumstance attributable 
apparently to the condition of the host; for the latter, although green, 
was not actively growing and the foliage, moreover, was everywhere 
severely affected by Puccinia cynodontis Desm. and Helminthosporium 
cynodonti Marignoni. About the middle of April, several weeks after 
tie resumption of active vegetative growth, the more recently unfolded 
leaves of Cynodon dactylon began to show newly developed lesions 
associated with conidiophores and conidia in a living state. At nearly 
the same time altogether similar foliar spots made lieir appearance on 
goose grass {Eleusine indica [L.] Gaertn.). Microscopical examination 
revealed no morphological difference in the fructifications present on 
the two graminaceous species. 
On July 13, 1922, a stand of Bermuda grass near Bladensburg, Md., 
was observed to be attacked by the fungus with unusual severity. Many 
of the leaves had been killed altogether, and of those that remained 
functional nearly all bore scores of discrete or confluenf spots, or extern 
sive whitened areas which often involved altogether from one-fourth to 
one-third of the tissues of the individual foliar organs. Plants of 
Agropyron repens distributed in the Bermuda grass likewise bore a 
sprinlding of the-foliar spots characteristic of the fungus, although in 
smaller quantity. On microscopical examination the similarity of the 
abundant fructifications on both Bermuda and quack grass collected in 
Maryland to those of the Florida parasite was readily apparent. Agropy¬ 
ron repens and Eleusine indica^ therefore, represent additional hosts of 
the interesting fungus described by Heald and Wolf (55). 
The foliar lesions bear a good deal of resemblance to those produced, 
for example, by Helminthosporium leersii. They first become visible as 
minute brown spots in green and otherwise healthy tissue. (PI. 10, A.) 
