Crop rotation phytosanitary analysis using organic farming principles in the Krasnoyarsk region conditions

The objective of research is to establish changes in the phytosanitary situation in the grain-row crop rotation when introducing fallow land into agricultural circulation using the principles of organic farming in the Chulym-Yenisei forest-steppe. The object of research is a crop rotation link (wheat-wheat-corn). The studies were conducted in 2021-2023 on the territory of land use of Rodnik LLC in the Balakhta District of the Krasnoyarsk Region on a 27-year-old fallow land introduced into agricultural circulation. The studied varieties of spring wheat Novosibirskaya 31, Novosibirskaya 16, Granni. Data on the number and species composition of pests, the prevalence of diseases and weeds in crops are presented. The number of pests was significantly lower than the economic threshold of harmfulness even with the repeated inclusion of wheat in crop rotation and amounted to an average of 8.3 thrips, 1 frit fly, and 2.3 meadow moth caterpillars per 100 net swings. In the first year of fallow land use, soil suppression was noted: the level of soil colonization by Bipolaris sorokiniana at the beginning of the growing season was 20 pcs/g of soil, decreasing to 10 pcs/g of soil by the end of the growing season. In the second year of the study, root rot was noted with a prevalence of 11.5-24.4 % during the tillering phase, septoria leaf spot during the heading phase - 25 %, ear diseases on the Novosibirskaya 16 variety - 57 %, on the Novosibirskaya 31 and Granni varieties - 44.3 and 38.4 %, respectively. A decrease in the number of weed species was shown by the years of agricultural use of the fallow land: 11, 10, 8 species, respectively, in 2021, 2022, 2023. The average number of weeds per 1 m2 increased and amounted to 44.3 pcs/m2 (2021), 84 (2022) and 442.0 pcs/m2 (2023). Over the three years of the study, the proportion of root-suckering perennial weeds increased significantly compared to the first year of the study.