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A North American System of Nomenclature for Puccinia recondita f. sp. tritici. D. L. Long, Cereal Rust Laboratory, U.S. Department of Agriculture, St. Paul, MN 55108; J. A. Kolmer, Research Station, Agriculture Canada, Winnipeg, Manitoba, Canada R3T 2M9. Phytopathology 79:525-529. Accepted for publication 12 December 1988. 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, 1989. DOI: 10.1094/Phyto-79-525.

A nomenclature system for designating virulence combinations of cultures of Puccinia recondita f. sp. tritici in North America is proposed by the North American Wheat Leaf Rust Research Workers Committee. Host seedling resistance genes Lr1, 2a, 2c, 3, 3ka, 9, 11, 16, 17, 24, 26, and 30 occur singly in each of the primary differentials. Host lines are grouped into sets of four, and infection types are recorded for each line. Avirulence and virulence of cultures are determined by low and high infection types, respectively. Virulence combinations are to be designated by a three-letter code followed by a hyphen and a listing of ineffective host genes in any supplemental differential host set used. Additionally, a current leaf rust resistance series that consists of host genes Lr19, 21, 25, 29, 32, and RL6059 (Lr33 + 34) is recommended for evaluating bulk collections or composites of individual cultures. A supplemental series of Lr12, 13, 22a, 22b, and 34 adult-plant resistance genes is recommended for evaluating virulence to adult-plant resistance to leaf rust.

Additional keywords: physiologic specialization, rust races, wheat leaf rust.