Kalatur K. Nematode and fungus diseases of sugar beet seedlings and methods of limiting their harmfulness under condition of the forest-steppe zone of Ukraine

The thesis deals with studies on nematodofauna of sugar beet rhizosphere and its role in the origin of black leg of seedlings. Species composition of phytonematodes of sugar beet in the zone of insecure and sufficient moistening of the forest-steppe zone of Ukraine was specified. The factors of dynamics of abundance of the nematodes of different ecological groups were analyzed, among them, cultural practices and weather conditions throughout the sugar beer vegetation proved to be of decisive importance. The data concerning the influence of the complex of parasitic nematodes and its separate species on the development of black leg and on productivity of the crop were presented. The thresholds of harmfulness of phytohelminths on sugar beet crop were calculated. On the basis of results of abundance of the phytoparasitic nematodes in soil and sugar beet yields were worked out. The influence of chemical methods (presowing seed theatment with fungicides and insecticides) on the abundance of the phytonematodes in the soil, development of black leg and productivity of sugar beet crop was studied