Effectiveness of Herbicides for Weed Control and Their Phytotoxicity for Sugar Beet depending on Age of the Treated Plants and Consumption Rates of Chemicals

In field experiments at the VNIISS experimental field, various combinations of herbicides were tested against juvenile dicotyledonous weeds in the sugar beet crop in 2018-2020, including preparations: Betanal maksPro (BMP), Betanal Expert OF (BEOF), Betanal 22, Mitron, Caribou. The effectiveness of chemical weeding has been investigated depending on the age of weeds and the rate of consumption of drugs. It is shown that the highest efficiency of chemical weeding (98-100%) in combination with low phytotoxicity for sugar beet was provided when processing the lowest (of the recommended) consumption rates of drugs in the early phases of weed development: cotyledons-the 1st pair of true leaves. The delay in herbicide treatment increased the heterogeneity of weeds in the development phase and reduced the effectiveness of chemical weeding. Sugar beet, especially in the early stages of development, experienced stress after the introduction of herbicides for 6 to 14 days. The duration of stress depended on the dose of herbicide, environmental conditions, and the phase of sugar beet development. With excessive application of herbicides, sugar beet plants were subject to a longer depression. The formation of productive indicators of sugar beet depends on weather conditions, the effectiveness of a combination of herbicides on weeds and their toxicological load on crop plants. The use of maximally permissible and increased herbicide consumption rates for overgrown weeds at all stages of chemical weeding created prerequisites for reducing the productive indicators of sugar beet. In experiments where relatively “rigid” herbicide schemes were used, the calculated sugar harvest decreased by 0.64-1.01 t/ha.