Disease Note

First Report of Ascochyta Leaf Spot Caused by Ascochyta hordei var. americana on Barley in New York. C. S. Huftalen, Department of Plant Pathology, Cornell University, Ithaca, NY 14853. G. C. Bergstrom, Department of Plant Pathology, Cornell University, Ithaca, NY 14853. Plant Dis. 70:1074. Accepted for publication 2 July 1986. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/PD-70-1074b.

During March and April of 1984, 1985, and 1986, irregular-shaped tan lesions with associated chlorosis were observed near the tips of lower leaves of several lines of winter barley (Hordeum vulgare L.) at early tillering in breeding nurseries near Ithaca, New York. The fungus Ascochyta hordei Hara var. americana Punith. was consistently isolated from the lesions; identification was based on yellow-brown submerged pycnidia, 157 ± 33 μm in diameter, with characteristically darkened cells around the ostiole. Conidia were medianly uniseptate, hyaline to pale yellow, and 25.2± 1.8 μm × 5.5±0.4 μm. Pathogenicity was confirmed on seedlings of Birka barley, and the fungus was successfully reisolated. To our knowledge, this is the first report of this fungus causing disease on any cereal in the northeastern United States; A. hordei is regarded as a minor pathogen on barley and wheat in northwestern states. Symptom development did not progress past the lower leaves on any of the plants we observed. Incidence of this disease may be underestimated because of the similarity of foliar symptoms to those induced by frost injury.