Races of Puccinia graminis on barley, oat and wheat in Canada in 2006

Abstract

Stem rust, caused by Puccinia graminis, is a disease of cereal crops worldwide. In Canada, it is primarily controlled using resistant cultivars. Tracking the virulence structure in the pathogen populations is essential to detect new virulent races that may occur. Surveys of barley (Hordeum vulgare), oat (Avena sativa) and wheat (Triticum aestivum) fields and trap nurseries were conducted to provide incidence and severity information and to identify the virulence structure in the pathogen populations. Stem rust samples were collected in Manitoba and Saskatchewan in 2006. Stem rust was not found on cultivated wheat and was at trace levels in barley and oat fields. From wheat and barley samples, four races of P. graminis f. sp. tritici were found and QFCSC (89%) was predominant. Thirteen races of P. graminis f. sp. avenae were found in 2006. From cultivated oat samples, the predominant races were TJJ (67%), TJS (17%), and TGD (9%). From wild oat samples, the predominant races were TJJ (40%), TGD (23%), and TGB (12%). Two new races of P. graminis f. sp. avenae (TGN and TJN) with virulence to Pg12 but avirulence to Pg13 were detected on both cultivated and wild oat both in Manitoba and Saskatchewan in 2006.