Mykhailenko S. Leaf diseases of spring barley in Polissya of Ukraine and measures for limitation of their harmfulness

Object - pathogens of spring barley leaf spots (Bipolaris sorokiniana Shoem, Drechslera teres Ito, Drechslera graminea Ito, Rhynchosporium graminicola Heinsen). Aim - to reveal peculiarities of leaf spots under conditions of Polissya of Ukraine and to substantiate measures for control of these diseases. Methods - phytopathological, mycological, statistical. Novelty of investigations - relation between date of appearance of first symptoms, average air temperature in April and precipitation in April was revealed. Using the method of regression analysis equation for dependency was received and model was built. Species composition of leaf diseases of spring barley was specified. For the first time for the Polissa zone of Ukraine incidence and harmfulness of complex of leaf disease of spring barley were investigated. It was established that the main pathogens are Bipolaris sorokiniana, Drechslera teres, Drechslera graminea, Rhynchosporium graminicola. Harmfulness of Bipolaris sorokiniana and Drechslera teres was established. It was noted, that disease infection affects ear length, number of grains in ear, weight of 1000 grains. Harmfulness of brown spot under 90% severity was 19,1%, net spot - 21,3%. Histological studies of penetration of Bipolaris sorokiniana and Drechslera teres in plant tissues of spring barley were conducted. More than 20 varieties of spring barley were tested. Resistant varieties were not registered.