Goal.To study the development of fungal diseases of winter wheat and to determine their harmfulness. Methods. The study was conducted using field (assessment of disease development on winter wheat varieties), laboratory (identification of pathogens of winter wheat), analytical and mathematical methods. Results. It was found that the most common diseases of winter wheat during 2017 -2019 were leaf septoria and dark brown spots. The harmfulness of dark brown spots and leaf septoria on the varieties Vodohray Bilotserkivskyi, Mudrist Odeska on artificial infectious backgrounds was studied. It should be noted that the fungal attack of winter wheat affected the economic indicators. The coefficient of harmfulness (on an artificial infectious background) on susceptible to dark brown spot varieties, depending on the level of disease development was 0.26 -0.49%, leaf septoria -0.14 -0.66%. Conclusions. Over the years of research, the development of dark brown spots (on the natural background), depending on the variety was 1.5 -28.5%, leaf septoria -1.5 -32.5%. Dark brown spot affected the least variety of Mudrist Odeska, leaf septoria -variety Oberig Myronivskyi. It should be noted that the fungal attack of winter wheat by leaf septoria and dark brown spot affects the length of the ear, the number of grains in it, the weight of grain in the ear, the weight of 1000 grains. Thus, with increasing lesions of leaf septoria of the variety Vodogray Bilotserkivskyi grain weight from the ear decreased, in particular at the intensity of the disease 50%, it decreased by 0.27 g, at 75% -0.57 g, 100% -by 0.81 g The disease affected significantly the weight of 1000 grains, which decreased with increasing degree of damage and with the development of the disease 25% was 2.7 g less, while in unaffected plants it was 45.7 g. With a lesion intensity of 75%, this figure decreased by 14.6 g. With the fungal attack by the dark brown spot of the variety Mudrist Odeska the mass of 1000 grains decreased and at the intensity of the disease 50% was 6 g less, while in unaffected plants it was 47 g, at the intensity of the defeat 75% this figure decreased by 10 g. The coefficient was determined of the harmfulness of leaf septoria on the artificial infectious background (0.14 -0.66%) and dark brown spot (1.5 -28.5%) on susceptible to diseases varieties.

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