VIEW ARTICLE

Etiology

Hordeum jubatum as a Source of Inoculum of Septoria avenae f. sp. triticea and S. passerinii. B. L. Shearer, Department of Plant Pathology, University of Minnesota, St. Paul, MN 55108, Present address: Agronomy Department, Institute of Agriculture, University of Western Australia, Nedlands, Australia 6009; B. Skovmand(2), and Roy D. Wilcoxson(3). (2)(3)Department of Plant Pathology, University of Minnesota, St. Paul, MN 55108, (2)Present address: CIMMYT, Londres 40, Mexico 6, D.F. Phytopathology 67:1338-1341. Accepted for publication 16 May 1977. Copyright © 1977 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-67-1338.

Of 125 samples of Hordeum jubatum collected throughout the cereal-growing region of Minnesota during a 3-yr period, 46% were infected with Septoria avenae f. sp. triticea and 19% with S. passerinii. The host range of isolates of S. passerinii was highly specialized; an isolate from H. vulgare infected cultivated Hordeum, and one wild Hordeum sp., whereas an isolate from H. jubatum infected H. jubatum and two other wild Hordeum spp. but not cultivated Hordeum. The host range of S. avenae triticea was less specialized; an isolate of S. avenae triticea from H. jubatum infected 21 accessions of cultivated Hordeum and 12 accessions of wild Hordeum. Isolates of S. avenae triticea from H. jubatum, H. vulgare, and Triticum aestivum completed their life cycles on all three hosts. Some of the isolates of S. avenae triticea from H. jubatum were more virulent than those from H. vulgare or T. aestivum. The results suggest that a wide range of Hordeum spp. could act as hosts to S. avenae triticea.