Effect of sowing dates on damage to corn by western corn beetle larvae in the Western Forest-Steppe

Goal. To identify the influence of corn sowing dates (Zea mays L.) on plant damage by diabrotica (Diabrotica virgifera virgifera Le Conte) larvae. Methods. field, mathematical and statistical to assess the reliability of the obtained data. Results. 18.4% and 19.2% of plants were damaged by the western corn beetle (WCB), respectively, and the average damage score was at the level of 1.5 and 1.8 when the seeds were sown in the early period at the level of the soil temperature regime of +8°C and +10°C. Shifting the dates of corn sowing to later times caused an increase in the intensity of damage to the root system of the agricultural crop. Sowing seeds when the soil was heated at a depth of 10 cm to +14 and +16°C, the average damage score was 2.9 and 3.6, respectively. There is a tendency to decrease the number of damaged plants in the specified variants of the experiment to the level of 17.2 and 14.2%. Shifting the sowing of corn to a later time has a negative effect on its grain productivity in conditions of damage to the root system by the larvae of WCB. The decrease in grain yield from the cob was 16.1 and 15.9% when sowing seeds in optimally early periods at the level of the soil temperature regime of +8 and +10°C, and with later sowing — 22.2—36.8%. Conclusions. Where there is a spread of the WCB the dates of sowing corn seeds in the conditions of the Western Forest Steppe affects its harmfulness. Optimum periods of corn sowing, during which the decrease in individual productivity of damaged plants is the smallest, compared to undamaged ones, is the level of the temperature regime of the soil at a depth of 10 cm — 8—10°C.