Liaska Y. "Corn pests and control of their number in the Left Bank Forest-Steppe of Ukraine"

The dissertation deals with the theoretical substantiation and practical solution of clarifying the entomocomplex of maize agrocenosis, improving the control elements of phytophagous numbers and assessing the resistance of maize hybrids against major pests in the Left Bank Forest-Steppe of Ukraine. The dissertation covers the results of research of peculiarities of the seasonal dynamics of the number and harmfulness of the dominant species of phytophagous in maize crops, depending on environmental conditions. The most vulnerable phases of growth and development of maize plants before invasion and damage by the main phytophages have been established. The biological features of the development of cotton bollworm the European corn borer in corn crops have been studied. The effectiveness of modern insecticides against the main pests and the resistance of maize hybrids against the dominant species of phytophagous were evaluated. The scientific novelty of the research is that the entomocomplex in maize crops has been studied in the conditions of the Left-Bank Forest-Steppe of Ukraine. Based on the monitoring, the species composition of maize phytophages was specified. 39 species belonging to 7 genera, 17 families were identified. The peculiarities of the biology of the cotton bollworm in the conditions of corn agrocenosis were studied for the first time and hydrothermal coefficients of pest development were calculated. A nine-point scale was developed to assess grain damage in corn cobs by cotton bollworm caterpillars. The resistance of 13 maize hybrids against the main phytophages was evaluated. Direct and relative losses of corn yield due to damage of corn grains by cotton moth caterpillars were calculated. The practical significance of the obtained results consisted in the study of species composition of the main maize pests, their prevalence and harmfulness, which requires enhanced protection of maize crops from the main phytophages. Based on the results of field research, the elements of the system of protection of maize crops from dominant phytophages have been improved. It was found that the highest technical efficiency of insecticidal pesticides against soil phytophages was observed in the variants with Force Zea 280 FS (5.5 l/t) and Poncho 600 FS (2.5 l/t). When using insecticides against caterpillars of the cotton moth on corn crops, the highest technical efficiency was provided by insecticides: Koragen 20 hp. (0.15 l/ha) and Ampligo 150 ZC, FC (0.2 l/ha). Carrying out protection of corn from cotton moth with one-time spraying of crops with insecticides Karate Zeon 050 μs (0.2 l/ha) and Ampligo 150 ZC, FC (0.2 l/ha) provides profitable production of corn grain at the level of 280.7 and 110, 2% respectively. The cultivation of less sensitive maize hybrids against damage by the cotton moth is economically advantageous, so the economic efficiency of growing a stable hybrid DN Svityaz in comparison with the unstable was at the level of 550 UAH/ha. The recommended elements of protection of corn crops introduced into production promote increase of productivity and quality of production from unit of the area.