Diseases of winter wheat in agrocenoses can be caused by various factors. However, one of the key factors is the accumulation of phytopathogenic microbiota in the soil, seeds and plant residues. The leading role in pathogenesis is played by representatives of the genus Fusarium Link and Alternaria Nees, which lead to a decrease in grain yield and its quality indicators. The purpose of the research was to establish the influence of sowing dates and predecessors of winter wheat on the level of grain infection by fusarium and alternariosis pathogens. The research was carried out on winter wheat varieties of The V.M. Remeslo Myronivka Institute of Wheat, NAAS of Ukraine Podolyanka, MIP Lakomka, Aurora Myronivska, MIP Fortuna, MIP Lada and MIP Yuvileyna are sown in two periods (I - September 25, II - October 5), after the predecessors of soybean and sunflower in the conditions of the central and northeastern Forest Steppe of Ukraine. Phytopathological analysis of the samples was carried out with the help of a microscope using special techniques and the species composition of the causative agents of seed infection was determined, and the species share was determined by the ratio of the affected wheat grain to their total number. During the years of research, the winter wheat grain was colonized by the pathogens Fusarium Link and Alternaria Nees. The level of development of seed infection of winter wheat sown after the predecessor soybean turned out to be lower compared to the predecessor sunflower. On average, over the years of research, the number of grains with internal infection by fungi of the genus Fusarium Link was noted in the range of 0–23.0% for the predecessor soybean and 0.4–32.1% for the predecessor sunflower. The level of grain infection by the pathogen Alternaria Nees varied from 18.9% to 87.2% for the soybean precursor and from 21.0% to 84.0% for the sunflower precursor. In the conditions of the central forest-steppe of Ukraine, the first sowing period of winter wheat restrained the development of the causative agent of fusarium wilt, but contributed to the infection of the grain by the causative agent of alternariosis. The selection of optimal sowing dates and predecessors is an organic component in the technology of growing winter wheat and at the same time - the basis of modern plant protection systems against a complex of harmful organisms, which makes it possible to reveal the genetic potential of the yield of each variety as widely as possible
fusaria, fungal pathogens, mycological analysis, species composition, Fusarium Link, Alternaria Nees, Triticum aestivum L.