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An Improved Method for Detection of Acremonium coenophialum in Tall Fescue Plants. Bradford B. Reddick, Assistant professor, Department of Entomology and Plant Pathology, University of Tennessee, Knoxville 37901-1071; Mary H. Collins, Research associate, Department of Entomology and Plant Pathology, University of Tennessee, Knoxville 37901-1071. Phytopathology 78:418-420. Accepted for publication 9 October 1987. Copyright 1988 The American Phytopathological Society. DOI: 10.1094/Phyto-78-418.

The tall fescue endophyte Acremonium coenophialum causes a physiological disorder of cattle known as fescue toxicosis. Protein-A sandwich, enzyme-linked immunosorbent assay (PAS-ELISA) was compared to a microscopic staining test and double-antibody sandwich ELISA (DAS-ELISA) and found to be more reliable in predicting infection levels in fescue pastures. Antisera produced against the fescue endophyte cross reacted only to other closely related fungi. The two pastures sampled had infection levels of 57 ± 7 and 80 ± 5%. The PAS-ELISA was superior to DAS-ELISA in that it had lower background absorbance readings from uninfected fescue samples and consistently higher absorbance readings from infected samples. The PAS-ELISA also used less antiserum per sample and agreed more times with the microscopic staining method than did DAS-ELISA. The PAS-ELISA was superior to the microscopic staining method in that more samples could be processed and it was more reliable because the microscopic staining method did not detect hyphae in known infected plants 4% of the time. This is the first report of the use of PAS-ELISA to detect a fungus.