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Pathotypes of Puccinia hordei with Virulence for the Barley Leaf Rust Resistance Gene Rph7 in the United States. Brian J. Steffenson, Department of Plant Pathology, North Dakota State University, Fargo 58105. Y. Jin, and C. A. Griffey. Department of Plant Pathology, North Dakota State University, Fargo 58105; and Department of Crop and Soil Environmental Sciences, Virginia Polytechnic Institute and State University, Blacksburg 24061. Plant Dis. 77:867-869. Accepted for publication 4 May 1993. Copyright 1993 The American Phytopathological Society. DOI: 10.1094/PD-77-0867.

The barley (Hordeum vulgare) accession Cebada Capa has been used extensively as a source of resistance to the leaf rust pathogen (Puccinia hordei) in the Virginia barley breeding program. Cebada Capa possesses the resistance gene Rph7; and in the mid-Atlantic region of the United States, cultivars derived from it have remained resistant to P. hordei since 1968. In 1990, outbreaks of leaf rust were observed in Virginia on cultivars carrying Rph7. Isolates of P. hordei collected from these cultivars were found to possess virulence on Cebada Capa in greenhouse and growth chamber experiments. In addition to Virginia, P. hordei isolates with Rph7 virulence were identified in Pennsylvania and California. This is the first report of Rph7 virulence in the North American population of P. hordei.