Kononenko J. Polymorphism of virulence of the causal organism of powdery mildew and resistance sources to pathogenе in Forest-steppe of Ukraine

Thesis is devoted to studying of interaction between barley plants and the causal organism of powdery mildew. In the research period it is established the resistance of modern varieties of winter and spring barley to the causal organism of powdery mildew. Disease development in Forest-steppe of Ukraine is defined. It was investigated the resistance of perspective sources on immunodefence to the causal organism of powdery mildew in field and laboratory conditions. It was identified the racial structure of the causal organism of powdery mildew on winter and spring barley in region Forest-steppes. New pathogene races were established. I develop the comparison of racial structure B. graminis f. sp. hordei on winter and spring barley. The research showed difference and the general races of the causal organism. It was defined the racial structure of populations of the causal organism before and after its transit of a sexual stage of development. There was presented the influence of sexual process on the racial structure of pathogenе. In my thesis I show the efficiency of known resistant genes and the encountered frequency of the most widespread genes of virulence.