Physiologic specialization of Puccinia recondita f sp tritici in Canada in 1994

In 1994 leaf rust of wheat (Triticum aestivum) caused by Puccinia recondita f. sp. tritici was first observed on June 19 in winter wheat fields in southern Manitoba. Warm and dry weather in June followed by cooler weather in July limited the spread and development of leaf rust in the prairies of Manitoba and eastern Saskatchewan. By the first week in August leaf rust severity levels in the Red River Valley were up to 40% on the moderately resistant cultivar Katepwa, and were up to 10% on the resistant cultivar Roblin. Phenotypes of leaf rust with virulences to resistance genes Lr3ka and Lr30 continued to increase in Manitoba and Saskatchewan, reaching 81% and 74%, respectively. Phenotypes with virulences to Lr2a and Lr2c decreased to less than 20%. Virulence phenotypes of P. recondita in Ontario and Quebec remained relatively unchanged from 1993 and previous years. A total of 38 virulence phenotypes were distinguished on 15 Thatcher wheat differential lines in 1994 in Canada.