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Ecology and Epidemiology

A Fungal Endophyte in Tall Fescue: Incidence and Dissemination. M. R. Siegel, Professor, Department of Plant Pathology, University of Kentucky, Lexington 40546; M. C. Johnson(2), D. R. Varney(3), W. C. Nesmith(4), R. C. Buckner(5), L. P. Bush(6), P. B. Burrus II(7), T. A. Jones(8), and J. A. Boling(9). (2)(3)(4)Research plant pathologist USDA-ARS, research plant pathologist, and associate professor, Department of Plant Pathology, University of Kentucky, Lexington 40546; (5)(6)(7)(8)Research agronomist USDA-ARS, professor, research agronomist USDA-ARS, and former graduate assistant, Agronomy Department, University of Kentucky; (9)Professor, Animal Science Department, University of Kentucky. Phytopathology 74:932-937. Accepted for publication 14 February 1984. Copyright 1984 The American Phytopathological Society. DOI: 10.1094/Phyto-74-932.

When tall fescue (Festuca arundinacea) is infected by the fungal endophyte EpichloŽ typhina (also referred to as Acremonium coenophialum) it causes summer toxicosis in grazing cattle. The endophyte was shown to be widely distributed and present at high levels of infestation in tall fescue fields in Kentucky. In individual plants the endophyte was found (in decreasing order of concentration) in leaf sheaths, seeds, crowns, stems, leaf blades, and roots. Very low amounts were recovered from leaf blades and roots, and high concentrations were found in the leaf sheaths and seeds. The endophyte was disseminated by seed and not by wind, rain, pollen, or mowing. During 4 yr the incidence of endophyte did not change significantly in experimental plots and fields managed for seed production (SP). Higher endophyte levels were found in SP plots than in those managed for hay-pasturage (HP). Hay yields and seed production in cultivar Kenhy tall fescue SP and HP plots were independent of the levels of the endophyte. The geographic origin of the endophyte in tall fescue, and the nature of the host-fungus relationships are discussed.

Additional keywords: epidemiology, forage crops, mutualism.