PHYSIOLOGICAL SPECIALIZATION OF PUCCINIA-RECONDITA F-SP TRITICI IN CANADA IN 1989

Leaf rust of wheat (Triticum aestivum) caused by Puccinia recondita f. sp. tritici was first observed on July 6 in southern Manitoba. The disease was not as prevalent in 1989 throughout the prairies of western Canada compared to previous years due to the dry conditions that prevailed over much of the region. Twenty-eight virulence combinations of P. recondita were detected in 1989 using 15 isogenic Thatcher backcross lines as differentials. Virulence was not detected to resistance genes Lr16, Lr19, Lr21, Lr25, and Lr29. In the prairie region the frequency of virulence to Lr11 increased to 44.3%. The leaf rust population in the prairie region was dominated by four virulence phenotypes; the populations in eastern Canada and British Columbia were more diverse.