Estimation of winter rye (Secale cereale L.) susceptibility to infection by powdery mildew (Blumeria graminis F. sp. secalis)

In cold and wet years, powdery mildew (<em>Blumeria graminis</em>) causes losses in the yield of winter rye (<em>Secale cerale</em> L.) amounting to 20%. In order to control the incidence of this disease and reduce the use of fungicides, it is recommendable to grow winter rye cultivars that are resistant or tolerant to infection by <em>Blumeria</em> <em>graminis</em>. The first step in the programmes of resistance-oriented cultivation of winter rye is the choice of adequate components for crossing. Such components should be characterized by resistance to powdery mildew infection, a trait which would be passed onto the new genotypes to be obtained. The paper discusses the outcome of research aimed at selecting inbred lines of winter rye distinguishable by the lowest susceptibility to infection by <em>Blumeria graminis</em>. The evaluation covered 233 winter rye genotypes which had been inoculated with a field population of the pathogen mentioned. The level of infection was defined in a five-point scale from 0 to 4 (the authors’ own scale). Next, the results were analyzed statistically. The genotypes under study were divided using Duncan’s test into homogeneous groups. Seven such groups were distinguished. The first homogeneous group, of the lowest level of infection, comprised five inbred lines of rye. These lines can serve as components for crossing experiments in programmes of resistance-oriented breeding.