Moroz S. Intra-stem Phytophagous of Sunflower, Features of Biology, Ecology and their Management in the Steppe of Ukraine

The relevance of research is determined by the fact that sunflower currently remains one of the main strategic agricultural crops of Ukraine, which are exportoriented and ensure food security. During the research years, a significant proportion of plants with a hollow stem was found, that depended on rainfall during the growing season and irrigation. The level of hollow stem reached up to 30% on the control area - without feeding, and up to 22 % under the usual technology of feeding by urea in the phases of 2, 6 and 10 true leaves. Crop losses in research variants ranged from 1.41 to 2.91 t/ha, respectively. The reasons for the productivity decrease were the productivity of plants, which often lay down with a hollow stem, that created additional losses during harvesting. In hollow stems, only Mordellistena parvula Gyll. was found, and Agapanthia dahli Richt. was not detected. This reflected the decrease in the trophic base - in hollow stems, the power of the pith outside layer («ring») was sufficient for the development of Mordellistena parvula Gyll. larvae and insufficient for the development of the Agapanthia dahli Richt.. It was established that the number of Mordellistena parvula Gyll. 5.27/ plant actually does not affect the yield, which was 4.46 t/ha. The usage of urea in a complex with micromineral nutrition and a systemic insecticide reduced the level of hollow stems. For plowing, the latter could not be used, but for disking - it is recommended as an ecological method insurance (suppression of the population of the Agapanthia dahli Richt. by the Mordellistena parvula Gyll. population), to weaken the reservation of the Mordellistena parvula Gyll.. Therefore, the decrease in the percentage of hollow plants on the one hand contributed to the increase in yield, on the other hand - the decreased in the reservation of Mordellistena parvula Gyll., which was achieved by regulating the irrigation regime or using a complex of micromineral nutrition.