Races of Puccinia graminis on wheat, barley, and oat in Canada, in 2002 and 2003

Abstract

Annual surveys of stem rust [Puccinia graminis] are conducted on cereals in Canada to provide information on virulence dynamics in the pathogen population. Wheat, barley, and oat samples were collected in Manitoba, Saskatchewan, Alberta, and Ontario in 2002 and 2003. Stem rust was absent on commercial wheat cultivars in either year. In 2002, stem rust on commercial barley cultivars ranged from trace to 7% severity in Manitoba and, in 2003, was at trace levels across the prairie region. In 2002, stem rust on commercial oat cultivars was heaviest (5%–50% severity) in eastern Manitoba and progressively diminished to trace levels in eastern Saskatchewan. In 2003, stem rust on oat was at trace levels across the prairie region. Eleven races of Puccinia graminis f. sp. tritici were found in trap plots of susceptible wheat, 8 on commercial barley, and 14 on wild barley. The predominant races on wheat and wild barley were RCRSK, QCCJN, and RCCJN in 2002, and QFCSR and QFCSH in 2003. The predominant races on commercial barley were QCCJ- and RCCJ-types, which are virulent against resistance gene Rpg1. Eight races of Puccinia graminis f. sp. avenae were found on commercial oat, and seven on wild oat. The predominant races on commercial oat were NA67 and NA29 (63.4% and 14.4%) in 2002, and NA67 and NA76 (77.8% and 10.4%) in 2003. NA67 and NA29 were also predominant on wild oat in 2002 (43.2% and 24.9%) and in 2003 (53.8% and 22.7%). Race NA28, which is virulent to resistance gene Pg-a and last reported in 1997, was found at two locations in Manitoba in 2003.

Keywords:

• Puccinia graminis
• stem rust
• virulence
• virulence phenotype
• wheat
• barley
• oat