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Abstract
In 1984, wheat leaf rust, caused by Puccinia recondita, was first observed in Manitoba on June 25. However, dry conditions in much of western Canada limited rust development and the disease did not damage wheat in 1984. Identification of races from leaf rust survey samples was carried out with 19 backcross lines, each with a single gene for resistance. Lines with genes Lr19, Lr21, Lr25, and Lr29and line T6 × PI58548 were resistant to all survey samples tested. Sixteen isolates from Manitoba were virulent on adult plants of Benito which has genes Lr1, Lr2a, Lr12, and Lr13. Virulence on gene Lr16 occurred in 17% of the isolates from Manitoba and greenhouse tests with 15 of these isolates showed that they were virulent on adult plants with gene Lrl3. Virulence on a line with gene Lr26 and on the cultivar Tobari occurred at a low level in the rust population. Virulence patterns of isolates from eastern Canada were similar to those observed in recent years. Fifty-nine virulence combinations were identified, using 17 single-gene lines as differentials.