A Variable-Spored Isolate of Drechslera dactylidis Pathogenic on Orchardgrass and Corn. K. E. Zeiders, Research Plant Pathologist, U.S. Regional Pasture Research Laboratory, Agricultural Research, Science and Education Administration, U.S. Department of Agriculture, University Park, PA 16802. Plant Dis. 64:211-213. Accepted for publication 10 October 1979. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1980. DOI: 10.1094/PD-64-211.

Drechslera (Helminthosporium) dactylidis causing severe leaf spot and blotch was isolated from orchardgrass (Dactylis glomerata) near State College, Pennsylvania. The fungus regularly produced a certain proportion of abnormally curved, branched, or staurate conidia in culture and on leaves of inoculated orchardgrass plants. Information on cultural characteristics, morphology, and taxonomy of D. dactylidis is presented and discussed. In greenhouse inoculations, the pathogenicity of D. dactylidis was tested on 18 gramineous species. Only orchardgrass and corn (Zea mays) were susceptible. Twelve forage grasses and four small grains were nonsusceptible, thus indicating a very narrow host range among Gramineae for this pathogen. Results indicate that D. dactylidis is a potential threat to orchardgrass and possibly corn, especially during the warm summer months. The ability of this fungus to attack corn was demonstrated for the first time.