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A Fungal Endophyte of Tall Fescue: Evaluation of Control Methods. M. R. Siegel, Professor, Department of Plant Pathology, University of Kentucky, Lexington 40546; D. R. Varney(2), M. C. Johnson(3), W. C. Nesmith(4), R. C. Buckner(5), L. P. Bush(6), P. B. Burrus, II(7), and J. R. Hardison(8). (2)(3)(4)Research associate, research plant pathologist, USDA-ARS, and associate extension professor, Department of Plant Pathology, University of Kentucky, Lexington 40546, respectively; (5)(6)(7)Research agronomist, USDA-ARS, professor, and research agronomist, USDA-ARS, Agronomy Department, University of Kentucky, respectively; (8)Research plant pathologist, USDA-ARS, Department of Botany and Plant Pathology, Oregon State University, Corvallis 97331. Phytopathology 74:937-941. Accepted for publication 14 February 1984. Copyright 1984 The American Phytopathological Society. DOI: 10.1094/Phyto-74-937.

Treatment of tall fescue (Festuca arundinacea) field plots with either one late spring foliar application of benomyl, triadimefon, thiabendazole, etaconazol, or imazalil or one spring granular application of triadimefon or etaconazol did not result in control of the tall fescue fungal endophyte EpichloŽ typhina (also referred to as Acremonium coenophialum). Soil treatment of infected potted plants with bitertanol was partially successful. Storage at 21 C, short-term heat treatments, and fungicide treatments of infected seed were effective in destroying endophyte viability in greenhouse and field tests. Endophyte viability in infected seed was lost after 7- 11 mo of storage at 21 C, but not after 19 mo of storage at temperatures <6 C. The heat treatment at 57 C for 40 min or at 49 C for 7 days controlled the endophyte, but 9- 16% loss of seed viability occurred. Some seed treatment fungicides reduced germination and seedling vigor in the greenhouse. Certain formulated triazole fungicides were nontoxic or only slightly phytotoxic. These included a 40% dust formulation of triadimenol and a wettable powder formulation of bitertanol. Two flowable formulations of triadimenol were effective seed treatment fungicides that controlled the endophyte in a field test.

Additional keywords: forage crops, triazole fungicides.