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Influence of Nutrition on the Formation of Basidia and Basidiospores in Thanatephorus cucumeris. Gerard C. Adams, Jr., Research assistant, Department of Plant Pathology, University of California, Davis 95616; Edward E. Butler, professor, Department of Plant Pathology, University of California, Davis 95616. Phytopathology 73:147-151. Accepted for publication 16 June 1982. Copyright 1983 The American Phytopathological Society. DOI: 10.1094/Phyto-73-147.

Isolates of Thanatephorus cucumeris and related fungi were grown on agar media in two-compartment petri plates. One compartment of each plate contained an inoculated growth medium. After 2- 3 days, mycelium grew into the other compartment, which contained a sporulation medium. Amounts of NaNO₃ and glucose were varied primarily in the growth medium and to a limited extent in the sporulation medium. The optimum levels of NaNO₃ and glucose for inducing the perfect state were defined for several isolates belonging to anastomosis groups (AG) AG-1 and AG-4, and one isolate of AG-5. The nutritional conditions favoring the formation of basidia by isolates in AG-1 and AG-4 were the initial level of nitrogen and glucose in the growth medium and growth from this medium onto a medium very low in nutrients. Formation of basidia on the sporulation medium was greatly enhanced by solidifying it with Difco Bacto agar rather than Difco purified agar. A water-soluble factor present in Bacto agar stimulated basidial formation when added to the sporulation medium solidified with purified agar. No isolate of AG-2, AG-3, or other Rhizoctonia or Sclerotium species sporulated on agar media.