Phytosanitary condition of maize agrocoenosis depending on measures to regulate pest organisms in the conditions of the northern steppe of Ukraine

Abstract

The article presents the results of a study on the impact of primary soil cultivation methods and herbicide application schemes on the productivity of maize hybrids Miting, Varkhol, and Blackrock. The research findings indicate that the application of different primary soil cultivation methods significantly affects the population of dominant harmful organisms whose life cycles are associated with the arable layer of soil. For instance, in the variant with plowing, the spread of sclerotinia in the Varkhol hybrid crops was 11.6%, while in the crops of the Blackrock and Miting hybrids it was 10.4% and 8.3%, respectively. In contrast, in the variant with disk tillage, the spread of white rot in Miting hybrid crops was 9.3%, while in the crops of Varkhol and Blackrock hybrids it was 16.9% and 14.5%, respectively. The use of different primary soil cultivation methods also influenced the population of soil dwelling phytophagouses and pests, part of whose biological cycle is associated with the surface layer of soil. For example, under plowing, the population of Agriotes sputator L. ranged from 3.5 to 4.0 pests/m², while Pedinus femoralis L. had a population density of 1.5-2.0 pests/m², Ostrinia nubilalis Hbn had 1.5-1.8 pests/plant, and Scotia segetum Schiff. Eux. had 2.0-2.5 pests/m². These numbers were significantly lower compared to variants where disk tillage was used. The method of soil cultivation had the greatest impact on the group of harmful organisms known as weeds. Under plowing, the total number of weed species before harvesting in the control group without herbicide application was 117.9 weeds/m², while in the chiseling variant this figure was 131.3 weeds/m², and under disk tillage it reached 167.3 weeds/m². The application of different herbicide application schemes had varying effects on weed infestation levels and was characterized by different levels of control over segetal vegetation. The most effective scheme turned out to be a combination of pre-emergence (Fortendo KS, 4.0 l/ha) and post-emergence (Mezotrek Ultra MD, 2.0 l/ha) applications, which resulted in high technical efficiency of herbicide use ranging from 95.7% to 97.0%, depending on the variant. The highest maize grain yields were obtained in the variant with plowing using pre-emergence and post-emergence herbicide applications, where it amounted to 11.78 t/ha for the Miting hybrid and 11.22 t/ha and 10.54 t/ha for the Blackrock and Varkhol hybrids, respectively. Key words: maize, pests, phytopathogens, weeds, pesticides, hybrids, yield.