Virulence Spectrum of Puccinia hordei in North Africa and the Middle East. Amor H. Yahyaoui, Graduate Research Assistant, Department of Plant Pathology, Montana State University, Bozeman 59717. E. L. Sharp, Professor, Department of Plant Pathology, Montana State University, Bozeman 59717. Plant Dis. 71:597-598. Accepted for publication 12 December 1986. Copyright 1987 The American Phytopathological Society. DOI: 10.1094/PD-71-0597.

New virulence types of Puccinia hordei were detected in various geographic regions of North Africa and the Middle East. Isolates able to overcome many sources of resistance were identified. The P. hordei virulence types reported in this paper have not been previously identified. They are important not only because they are virulent on the commonly grown barley cultivars but because they are also virulent on the many barley cultivars containing Pa genes used as sources of resistance. The effectiveness of Pa₉ to these virulence types was not complete, but Pa₃ and Pa₇ were very effective against all P. hordei isolates tested. The naturally occurring Ornithogalum spp. in northern and northwestern Tunisia and Merchouch in Morocco may represent a breeding ground for new physiologic races of the P. hordei fungus. Isolates originating from the alternate host were as variable in virulence as those isolated from barleys in the same fields.