Virulence and Epidemiology of Puccinia recondita f. sp. tritici in the United States in 1984. D. L. Long, Plant Pathologist, Cereal Rust Laboratory, USDA, ARS, Department of Plant Pathology, University of Minnesota, St. Paul 55108. J. F. Schafer, and A. P. Roelfs, Research Plant Pathologists, Cereal Rust Laboratory, USDA, ARS, Department of Plant Pathology, University of Minnesota, St. Paul 55108. Plant Dis. 70:395-397. Accepted for publication 8 November 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-70-395.

Puccinia recondita f. sp. tritici isolates were obtained from wheat leaf collections made by cooperators throughout the United States and from cereal rust field surveys of the Great Plains and Gulf Coast in 1984. Testing of 836 isolates for virulence to 12 single-gene differentially resistant tester lines showed 39 virulence/avirulence phenotypes, which were categorized into seven defined Unified Numeration races. No virulence was found to 12 additional entries in a resistant tester series. Regional race distribution patterns indicated that the central United States was a single epidemiological unit, whereas the eastern and western regions consisted of several separate epidemiological areas.

Keyword(s): plant disease monitoring, wheat leaf rust.