Herbicides’ efficiency in a weed control on winter wheat sown in the steppe part of Kabardino-Balkaria

In 2018–2020 there was studied the efficiency of new herbicides ‘Fenizan’, VR (water solution 360 + 22.2 g/l) and ‘Avroreks’, KE (332 + 21 g/l) at various doses (0.14-0.2 and 0.5–0.6 l/y) against weeds on the sowings of a new winter wheat variety ‘Pamyati Shatilova’ (co-breeding of the Institute of Agriculture of the Kabardino-Balkarsky Research Center of the Russian Academy of Sciences” and the National Grain Center named after P. P. Lukyanenko) in the conditions of the steppe part of Kabardino-Balkaria. The purpose of the current study was to identify more effective doses of these herbicides with a single application. As a control (without herbicides), there was adopted an agrotechnical method, namely harrowing across the direction of BZSS-1.0 crops in the tillering phase in spring. The soil of the experimental plot was an ordinary (calcareous) blackearth of heavy loamy granulometric composition. The arable (0–20 cm) layer contained 3.0–3.5 % of humus; 100 g of soil contained 1.56–2.87 % of Р2О5 (according to Machigin); 3.61–4.30 mg of K2O (according to Machigin); 6.8–7.0 of pH. The average annual rainfall is 360–400 mm. There was found that in the control variant, the total number of weeds decreased by 26.3 %, while the number of perennials remained unchanged. On variants with the use of herbicides, weediness of crops decreased on 71.1–83.8 %, including the increase of perennials on 52.6–80.7 %. A higher effect was obtained at 0.2 l/ha (73.2 and 60 %) of ‘Phenizan’, VR and 0.6 l/ha (83.8 and 80.7 %) of ‘Avroreks’, KE. By the time of winter wheat harvesting, the least amount of weeds was identified on the variants using these herbicides. The best results in reducing weeds’ amount were obtained from the use of ‘Avroreks’, KE at dosages of 0.5 and 0.6 g/l – 150–175 g/m2 of weeds, the percentage of their death was 88.9–93.6. The indicators of grain yield structure and the average yield for 3 years (46.7 and 47.7 c/ha) on the experimental variants were also in favor of ‘Avroreks’, KE (0.6 g/l). The yield increase in comparison with the standard herbicide ‘2.4-D Zernomaks’, KE was 17.4%, and with the control it was 29.6 %.