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Detecting Viable Acremonium Endophytes in Leaf Sheaths and Meristems of Tall Fescue and Perennial Ryegrass. R. E. Welty, Research Plant Pathologist, Agricultural Research Service, USDA, Oregon State University, Corvallis 97331. M. D. Azevedo, Biological Technician, Agricultural Research Service, USDA, and K. L. Cook, Graduate Student, Department of Botany and Plant Pathology, Oregon State University, Corvallis 97331. Plant Dis. 70:431-435. Accepted for publication 14 October 1985. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1986. DOI: 10.1094/PD-70-431.

A method was developed to detect viable hyphae of the endophytic fungi Acremonium coenophialum or A. loliae in seedlings of tall fescue or perennial ryegrass, respectively. Captafol 4F (479 g a.i./L) at 7,489 Μg a.i./ml of deionized water was used to treat seeds of two strains of tall fescue (KY-82-3G1-316 and KY-37G1-307) and perennial ryegrass (cultivar Repell). The fungicide retarded or eliminated the growth of seedborne species of Alternaria, Cladosporium, and Epicoccum but did not influence the recovery of A. coenophialum or A. loliae from seedlings. Captafol at 14,978 Μg a.i./ml stunted the roots of 3-wk-old tall fescue seedlings; shoots were not affected. No phytotoxicity was observed at 7,489 and 3,745 Μg a.i./ml. When used with seedling staining and microscopic examination, the method detects viable endophyte in leaf sheaths and meristems of 3-wk-old seedlings, reduces incubation time required for seedling examination, and eliminates greenhouse culture. Seed technologists were trained to detect endophyte hyphae by this technique. Several media, including potato-dextrose, cornmeal, and bran-malt agars, were suitable for growth of A. coenophialum or A. loliae in culture.