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Resistance

Analysis of Symptoms on Spring and Winter Wheat Cultivars Inoculated with Different Isolates of Septoria nodorum. A. L. Scharen, Plant pathologist, USDA, ARS, Department of Plant Pathology, Montana State University, Bozeman 59717; Z. Eyal, associate professor, Department of Botany, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel. Phytopathology 73:143-147. Accepted for publication 18 June 1982. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1983. DOI: 10.1094/Phyto-73-143.

Ten winter and spring wheats that differed in level of resistance were quantitatively inoculated with 14 different cultures of Septoria nodorum. Symptoms measured were the number of lesions per square centimeter and the percentage leaf area necrotic on seedlings. The wheats differed in responses to the single isolates of S. nodorum from uniformly mild (winter wheats Anderson, Coker 68-8, and Redchief) to uniformly severe (spring wheats Fortuna and Polk). Moderate cultivar × isolate interactions were found in the winter wheats 91-728, Centurk, and Flint and in the spring wheat Olaf. Seedling disease severity agreed with glume blotch severity in the field on all cultivars in some test locations, but not in others. However, the pathogenicity patterns expressed by the 14 isolates of S. nodorum were not correlated with geographic origin. Pathogenic interactions were classified as resistant, intermediate, or susceptible. The magnitude of pathogenic interaction within the intermediate class was relatively low and since no isolate was found virulent on the uniformly resistant cultivars, no attempt was made to classify pathogenicity patterns into defined physiologic races.