Races of Puccinia graminis in the United States and Mexico During 1982. A. P. Roelfs, Research Plant Pathologist, Cereal Rust Laboratory, USDA, ARS, University of Minnesota, St. Paul 55108. D. L. Long, Plant Pathologist, and D. H. Casper, Research Technician, Cereal Rust Laboratory, USDA, ARS, University of Minnesota, St. Paul 55108. Plant Dis. 67:1238-1241. Accepted for publication 16 May 1983. 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, 1983. DOI: 10.1094/PD-67-1238.

Stem rust of oats and wheat were generally present in trace amounts in 1982. Oat stem rust was retarded by poor conditions for infection during the early part of the growing season in the principal oat-production area in the north central United States. Wheat stem rust was further restricted by the wide use of resistant cultivars in Mexico and the entire Great Plains of the United States. The principal race of oat stem rust in Mexico and the United States was NA-27, virulent on host genes Pg-1, -2, -3, -4, and -8. The 15-TNM was the principal wheat stem rust race in the United States (virulent on Sr5, 7b, 8, 9d, 9e, 10, 11, 16, 17, 36, and Tmp). In Mexico, races 113-RKQ (virulent on Sr5, 6, 7b, 8, 9a, 9b, 9d, 15, 16, 17, and 36) and 151-QFB (virulent on Sr5, 8, 9a, 9d, 15, 16, and 17) were most frequent. No virulence was found in oat stem rust for host genes Pg-9, -13, -16, and -a or in wheat stem rust for Sr13, 22, 24, 25, 26, 27, 29, 31, 32, 33, 37, Gt, and Wld-1.