Virulence Types of Puccinia hordei from North America, North Africa, and the Middle East. M. Reinhold, Postdoctoral Fellow, Department of Plant Pathology, Montana State University, Bozeman 59717. E. L. Sharp, Professor of Plant Pathology, Department of Plant Pathology, Montana State University, Bozeman 59717. Plant Dis. 66:1009-1011. Accepted for publication 31 December 1981. Copyright 1982 American Phytopathological Society. DOI: 10.1094/PD-66-1009.

The virulence patterns of several Puccinia hordei (leaf rust) isolates originating in North America, North Africa, and the Middle East were determined by using a differential set of barley (Hordeum vulgare) cultivars representing the genes Pa–Pa₉. Twelve different virulence types were found among the 14 isolates tested. The isolates collected in Montana were found to be more virulent than those collected in Texas and Minnesota. The isolate from Sakha (Egypt) appeared to have accumulated the highest number of virulence genes among the virulence types from North Africa. None of the isolates possessed virulence against the resistance genes Pa₃ in Estate and Pa₇ in Cebada Capa. CI 1243 carrying the gene Pa₉ was resistant to all isolates of P. hordei except for one isolate that originated from the alternate host (Ornithogalum spp.) near Tel Aviv, Israel. There was little similarity of reaction on cultivars reportedly carrying the Pa₂ gene or a complex of that gene, indicating that the Pa₂ complex involves more than one gene.

Keyword(s): barley leaf rust.