VIEW ARTICLE

Genetics

Selective Influence of Wheat Cultivars on Pathogenicity of Mycosphaerella graminicola (Anamorph Septoria tritici). Hafiz U. Ahmed, Department of Botany and Plant Pathology, 2082 Cordley Hall, Oregon State University, Corvallis 97331-2902, Current address: Plant Pathology Division, Bangladesh Rice Research Institute, Joydepur, Gazipur 1701, Bangladesh; Christopher C. Mundt, Molly E. Hoffer, and Stella M. Coakley. Department of Botany and Plant Pathology, 2082 Cordley Hall, Oregon State University, Corvallis 97331-2902. Phytopathology 86:454-458. Accepted for publication 15 January 1996. Copyright 1996 The American Phytopathological Society. DOI: 10.1094/Phyto-86-454.

Populations of Mycosphaerella graminicola isolated from winter wheat cultivars near crop maturity were subsequently evaluated on seedlings of the same wheat cultivars in the greenhouse. Significant pathogen population effects, cultivar effects, and pathogen population × cultivar interactions were demonstrated. Pathogen populations isolated from susceptible cultivars produced higher levels of disease, averaged over cultivars, than did populations isolated from moderately resistant or resistant cultivars, indicating that susceptible cultivars selected for higher levels of pathogen aggressiveness in the field. In addition, pathogen populations were more virulent on the cultivars they were isolated from in the field than on other cultivars, indicating selection for cultivar-specific virulence.