THE INFLUENCE OF HYDROTHERMAL FACTORS ON THE SPREAD AND DEVELOPMENT OF DISEASES IN AGROCENOSES OF CEREALS OF THE RIGHT-BANK FOREST-STEPPE

he dynamics of the spread and development of diseases in winter wheat and oat agrocenosis under the conditions of the Right-bank Forest Steppe have been investigated. It was established that during 2017–2019, septoria and powdery mildew were the dominant diseases in winter wheat crops, while in oats the main disease was powdery mildew. During the vegetation period, powdery mildew spread by an average of 40.6% of wheat plants and septoria disease - by 47.8%. In the agrocenosis of oats, the spread of powdery mildew was 67.4% over the three years. The peculiarities of the development of powdery mildew pathogens in winter wheat and oat agrocenosis, depending on hydrothermal factors (average daily temperatures and rainfall) during the vegetation season, have been analyzed. The arid conditions of vegetation period in 2017 (GTC 0.51) were not favorable for the development of mycosis in cereal crops compared to 2018 and 2019 (GTC 1.32 and 1.15). The average prevalence of diseases in 2017 was twice less than that of 2018 and 2019, and the intensity of the development decreased by 1,5-3 and 2,4-4,0 times (powdery mildew on wheat and oats) and 0,4-4,3 times (septoria on wheat). Due to excessive humidity (189-229 mm) and high air temperature (more than 25 ° C), there is an active development (up to 40%) of pathogens in cereal crops, which can cause morbid affection of more than 50% of crops. Under such conditions, the spread of powdery mildew on wheat plants reaches 45-53% and in the oat - up to 65-77%, the spread of septoria in wheat is up to 59- 60%.