Features of the development of the main sunflower diseases in the Eastern part of the Forest-Steppe of Ukraine

The author monitored the species composition of the main sunflower diseases and identified their harmfulness.A necessary condition for creating highly productive hybrids is to study the prevalence, development, and harmfulness of the main sunflower diseases, determine the species composition of pathogens, morpho-biological properties of pathogens, and optimize existing measures to protect the crop from diseases.Despite significant successes in breeding, the issue of creating highly productive sunflower hybrids that are resistant to the main diseases remains relevant.According to the results of field studies of the resistance of the studied material to dry rot of baskets in 2021-2024, sunflower samples were divided into two groups.Namely, resistant samples with a level of damage of 11.0-25.0%and medium-resistant -26.0-50.0%.The assessment of the field resistance of the studied sunflower samples in 2021-2024 to rust showed that the group of moderately resistant (26-50%) samples to rust consisted of the Yarilo hybrid, pollen sterility fixer lines OdOl1A and Sx588A, and two parental forms of the hybrids X1814B and X2283B.These samples had a resistance score of 5.The group of weakly resistant samples, with a resistance score of 7, consisted of the Kadet and Kosmos hybrids, the pollen sterility fixer line Sx66A, and the parental form of the hybrids X526B.Their incidence was 51.0-75.0%.As a result of the records in the experimental years regarding the damage of the studied sunflower samples by Phomopsis, the group of resistant samples, the level of damage of which did not exceed 10.0%, was made up of the pollen sterility fixer line 66, the parental form of the hybrids 2283, as well as the hybrids Kadet and Kosmos (resistance score 1).The maternal form of the hybrid Kadet -1, the hybrid Yarilo and the parental forms of the hybrids 1814 and 526 were found to be moderately resistant (11.0-25.0%).They had a corresponding resistance score of 2. The pollen sterility fixer line 588 had a resistance score of 3 and was classified as weakly resistant, while having a pathogen infection rate of 28.0%.According to the results of the research (2021)(2022)(2023)(2024), the group of highly resistant to downy mildew of sunflower was made up of the Kadet and Yarilo hybrids, as well as the parental form of the X1814V hybrid.Their NBR infection during the research years was 0.0% and the corresponding pathogen resistance score was 0. Two pollen sterility fixer lines Sx66A and Sx588A, two parental components of the X526V and X2283V hybrids, as well as the Cosmos hybrid, were resistant to the pathogen.Their pathogen infection level did not exceed 10.0% and the corresponding resistance score was 1.The pollen sterility fixer line OdOl1A showed average resistance to NBR.It had a resistance score of 2, and the pathogen infection of this sample was at the level of 24.0%.