Virulence of Puccinia recondita in the Pacific Northwest. E. A. Milus, Research Assistant, Department of Plant Pathology, Washington State University, Pullman, WA 99164. R. F. Line, Plant Pathologist, Agricultural Research Science and Education Administration, U.S. Department of Agriculture, Pullman, WA 99164. Plant Dis. 64:78-80. Accepted for publication 19 March 1979. 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, 1980. DOI: 10.1094/PD-64-78.

Virulence for resistance genes Lr1, Lr2a, Lr2b, Lr2d, Lr3a, Lr3bg, Lr10, Lr15, Lr16, Lr17, and Lr18 was found among collections of Puccinia recondita f. sp. tritici (the causal agent of wheat leaf rust) from Washington and adjacent Idaho and Oregon. No virulence for genes Lr3b, Lr3ka, Lr9, Lr11, Lr19, Lr24, LrEG, or LrT was detected. The races of P. recondita were most clearly differentiated on isolines having Lr1 and Lr2a. Western P. recondita race 1 (WPR-1) was avirulent on both isolines, WPR-2 was avirulent on Lr2a and virulent on Lr1, WPR-3 was avirulent on Lr1 and virulent on Lr2a, and WPR-4 was virulent on both isolines. Race WPR-2 is widely distributed throughout the Pacific Northwest east of the Cascade Mountains and is currently the most important race. More than 99% of the wheat acreage and all newly released cultivars in the Pacific North-west are susceptible to race WPR-2.