Potato mycocenoses in the fields of the Novozybkovsky district of the Bryansk region with different levels of radioactive contamination and economic use

The peculiarities of the formation of mycocenoses in potato plantings growing in fields with different levels of radioactive contamination and economic use were studied. The experiments were carried out in 1991–1998 in the fields of the Novozybkov agricultural experimental station in the Bryansk region (pollution density ^l37Cs = 1.2 ± 0.2 MBq/m²) and the lands of the Komsomolets Agricultural Complex withdrawn from economic use (^l37Cs >1.8 MBq/m²). Differences were noted in the incidence of potato plants with diseases in the field small–scale experiment (1992), depending on the fertilizers applied (background – peat manure compost (PMC) or additionally NPK + Mg), their balance (different doses of nutrients), as well as agricultural cultivation techniques. In the variants with the introduction of NPK + Mg and the use of the herbicide Promethrin SC or sodium humate, a significant decrease in the incidence of tubers with scab by 25–60% was revealed. Weather conditions influenced the development of pathogens. In 1994 rhizoctoniosis developed most actively in potato plantings and common scab on tubers (hydrothermal coefficient (GTС)_may–august = 2.35, which is significantly higher than the average long–term norm for 1991–1998–1.35). In the experiment on potatoes of the Temp variety of Belarusian selection (1994), the possibility of restraining the development of pathogens due to pre-planting treatment of tubers with fungicides was shown: when using contact the decrease in the total level of development of phytopathogens and saprophytes was 1.4 times less than in the control, and when using the systemic fungicide Tect 450 CS – 2.3 times. The use of biologically active substances for the pre-planting treatment of potato tubers (Agate-25K, TPS, Crezacin, KRP and Epin-Extra R) led to a decrease in plant infestation with late blight by 2.2–4.5 times, infestation of tubers with scab by 17–32%, rhizoctoniosis by 10– 36% and later than in the control, the development of diseases, which determined the tactics of fungicidal protection of potatoes during the growing season. There was an increase in potato yield by 11–29% and a significant decrease in the accumulation of¹³⁷Cs in tubers by 7–15%.