VIEW ARTICLE

A Form of Pyrenophora trichostoma Pathogenic to Wheat and Other Grasses. Robert M. Hosford, Jr., Department of Plant Pathology, North Dakota State University, Fargo 58102; Phytopathology 61:28-32. Accepted for publication 22 July 1970. DOI: 10.1094/Phyto-61-28.

A form of Pyrenophora trichostoma was severely pathogenic on wheat in North Dakota in 1968 and 1969. It caused light-brown lesions with distinct yellow halos on leaves, and formed abundant ascostromata on stubble. In the glasshouse, the fungus was pathogenic on common and durum wheats, other Triticum species, Agropyron species, brome grass, and rye; slightly pathogenic on barley; and not pathogenic on Elymus junceus, oats, corn, alfalfa, and flax. Triticum turanicum P.I. 184526 was highly resistant to all isolates. North Dakota spring wheat line 495 was very susceptible. Wheat cultivars varied in resistance, and isolates of the fungus varied in pathogenicity. Resistance in wheats was related to duration of free moisture on the leaves. At 23 C, the fungus produced immature ascostromata and characteristic dark mycelial columns on several media. At 16 C, it formed mature ascostromata on autoclaved wheat seed. Observations were used to outline a disease cycle.