STEM RUSTS ON WHEAT AND BARLEY IN CANADA, AND ON OAT IN CANADA AND MEXICO IN 1994

In 1994, stem rusts of wheat and barley [Puccinia graminis f. sp; trit ici] and of oat [P. graminis f. sp. avenae] were light in eastern Cana da, and in western Canada were confined mainly to the Red River Valley of Manitoba. Maximum infections of 10% and 5%, respectively, that dev eloped in lines of susceptible wheat in nurseries and in commercial ba rley fields in Manitoba were too low to cause significant damage. Infe ctions of wild oat did not exceed 10% and were confined to Manitoba. I n collections made from wheat in Canada, race QFCQ was the most common (43.1%), followed by races QCCG (40.3%), QCCJ (8.3%), QFCS (4.2%), TP MK (2.8%), and RKQQ (1.4%). From cultivated barley, race QCCG was the most common (77.6%), followed by QFCQ (12.3%), QCCJ (8.8%), and RKQQ ( 1.8%). Of all collections from wild barley, 68.9% were P. g. secalis. All isolates of P. g. tritici collected from wheat, cultivated barley, and wild barley in Manitoba were virulent to genes Sr5, Sr21, Sr9g, S r9d. All isolates were avirulent to genes Sr9e, Sr11, SrTmp, Sr13, Sr2 2, Sr24, Sr25, Sr26, Sr27, Sr29, Sr30, Sr31,Sr32, Sr33, Sr37, and Sr40 ; to the lines Mida-McMurachy-Exchange, Frontana-K58-Newthatch, CI8154 /Frocor, Alpha 16, BW197, RL6076, RL6088, RL6172; to the cultivars Ken ya Farmer, Agatha, Glenlea, Katepwa, Leader, Roblin, AC Taber, Grandin , and AC Domain; and to the durum cultivars AC Plenty, AC Melita, and Sceptre. Oat stem rust did not cause significant losses in Canada or M exico in 1994. In Manitoba, race NA27 of P. g. avenae was the most com mon (58.3%), followed by race NA29 (39.5%), NA23 (1.6%), and NA68 (0.5 %). In Mexico, race NA27 also was the most common (58.1%), followed by NA29 (40.3%) and NA30 (1.6%).