Stem rusts on wheat, barley, and oat in Canada in 1996 and 1997

Abstract

In 1996, stem rusts of wheat and barley [Puccinia graminis f. sp. tritici] and oat [P. graminis f. sp. avenae] were light in eastern Canada, and in western Canada they were confined mainly to the Red River Valley of Manitoba, where maximum severities of 40% occurred in lines of susceptible wheat in nurseries. In 1997 only traces of stem rust were found on any host at any location. There were no infections in commercial wheat fields in 1996 or 1997. Only trace levels of stem rust were found in cultivated barley both years. There was no stem rust in commercial oat fields in 1996 or 1997. Infections in wild oat did not exceed 15% in either year and occurred only in Manitoba. In 1997, most isolates collected from cultivated or wild barley, and about one-half of those collected from wheat, were rye stem rust [P. graminis f. sp. secalis]. Pathotype identification was made on only 14 collections obtained from wheat, and on 19 from wild or cultivated barley in Manitoba in 1997. During both years, 24 pathotypes of...