Identification of New Races of Puccinia graminis f. sp. avenae . D. E. HARDER, Agriculture Canada Research Station, 195 Dafoe Road, Winnipeg, Manitoba, R3T 2M9. Plant Dis. 78:367-368. Accepted for publication 28 December 1993. Copyright 1994 Department of Agriculture, Government of Canada. DOI: 10.1094/PD-78-0367.

Twenty-two new races of Puccinia graminis f. sp. avenae were identified from field collections made in Canada since 1985 or from 1,500 isolates held in storage since 1953 at the Agriculture Canada Research Station in Winnipeg. The stored isolates, previously identified by older nomenclature systems, were recovered and reidentified using the current nomenclature of NA races for this pathogen. The new races are listed, along with previously identified races, to provide a key for the known variation in P. g. avenae in North America. Samples of the new races are available upon request.

Keyword(s): oat stem rust, physiologic specialization