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Typhula Species Pathogenic to Wheat in the Pacific Northwest. G. W. Bruehl, Professor, Department of Plant Pathology, Washington State University, Pullman, Washington 99163; B. M. Cunfer, Assistant Professor, Department of Plant Pathology, University of Georgia, College of Agriculture Experiment Stations, Georgia Station, Experiment, Georgia 30212. Phytopathology 65:755-760. Accepted for publication 3 February 1975. DOI: 10.1094/Phyto-65-755.

Typhula spp. parasitizing wheat can be identified if several morphological characters are used. T. incarnata can be identified by its reddish-brown sclerotia and pink basidiocarps, usually by the shape of its basidiospores, and by occasional digitate cells in the sclerotial rind. It is difficult to distinguish T. idahoensis from T. ishikariensis, both of which have black sclerotia. The basidiocarps of T. idahoensis are smaller than those of T. ishikariensis, and the fertile heads are brownish rather than whitish. The size and shape of basidiospores of different collections of the two species are similar, so spores are not diagnostic. Sclerotia of T. idahoensis are less globose and more frequently borne within host tissues, and the rind cell patterns are more irregular than those of T. ishikariensis. Typhula incarnata is the least virulent on all hosts. T. idahoensis is virulent on winter cereals and some grasses, but on few dicotyledonous species. T. ishikariensis is virulent on winter cereals, grasses, legumes, and many other dicotyledonous species. T. incarnata thrives on early-seeded winter cereals throughout the northern half of eastern Washington, whereas T. idahoensis and T. ishikariensis are restricted to areas of frequent prolonged snow cover. T. idahoensis is dominant on former grasslands or grass-sagebrush lands; T. ishikariensis is dominant on former forest lands. Light intensity within plant refuse may be less than 10 percent of unimpeded light. Because variation in basidiocarp size and color results from low light intensity, only basidiocarps which have matured in full light should be used for species diagnosis.