APPLICATION OF POST- EMERGENCE HERBICIDES AND THEIR IMPACT ON SUNFLOWER PLANT PRODUCTIVITY

Abstract

The aim of the study was to determine the impact and effectiveness of the use of post-emergence herbi- cides with the d.r. tribenuron-methyl, 750 g/kg and d.r. imazamox (33 g/l) + imazapyr (15 g/l) on the degree of crop contamination and sunflower seed yield in the con- ditions of the South of Ukraine. Methods. The study was conducted during 2022-2024 in the fields of the FG «Plakushchenko V.V.», located in the territory of the Odessa region, Velykymykhailivskyi district in the village of Grebenyky. The method of laying the field experiment – split plots, main plots 1). (Control (without herbicide appli- cation); application of a post-emergence herbicide with the active substance (d.r.): 2). d.r. tribenuron-methyl 750 g/kg, at a rate of 35 g/ha, 3). d.r. imazapyr (15 g/l) + imazamox (33 g/l), at a rate of 1.1 l/ha; 4). Manual weeding. Wide-row sowing with a row spacing of 70 cm. The area of the sowing plot is 60 m2, the accounting area is 50 m2, in four repli- cates. Research results. When using the herbicide with the d.r. imazapyr (15 g/l) + imazamox (33 g/l), the num- ber of common nettle was 0.1 and field birch – 0.2 pcs/m2, while when using tribenuron-methyl (750 g/kg) the number of weeds was 0.2 pcs/m2 higher. On the other hand, when using tribenuron-methyl (750 g/kg) the number of quinoa (species) was 0.5 less, and Theophrastus’s rope by 0.2 pcs/m2 than when using the herbicide with the d.r. imazapyr (15 g/l) + imazamox (33 g/l). As for cereal weeds, in our case, mouseweed (species) and winter barley fallow, then the herbicide with the d.r. tribenuron-methyl (750 g/kg) does not destroy them, and their number was 2.3 and 1.5 pcs/m2 at the control variant level, respectively, and therefore it is necessary to additionally apply anti-grass herbicides. The lowest yield was obtained in the control variant: in 2022 0.57 t/ha, in 2023 ‒ 1.06 t/ha, in 2024 ‒ 1.19 t/ha and on average over three years ‒ 0.94 t/ha, with an oil content of 48.93% and an oil yield of 0.46 t/ha, and the maximum with manual weeding ‒ 1.50, 2.04, 2.20 and 1.91 t/ha and 50.75% and 0.97 t/ha, respectively. The use of post-emergence herbi- cides contributed to a reduction in the number of weeds in crops, and accordingly, increased crop yield. Thus, when using tribenuron-methyl (750 g/kg), an increase in control was obtained in 2022 of 0.65 t/ha, in 2023 – 0.62 t/ha, in 2024 – 0.64 t/ha and on average over three years – 0.64 t/ha, and when using imazapyr (15 g/l) + imazamox (33 g/l) – 0.81, 0.72, 0.73 and 0.97 t/ha, respectively. Conclusions. The use of post-emergence herbicides reduced the num- ber of weeds compared to the option without herbicides, but complete destruction of weeds was not achieved in any of the options and each herbicide had a different effect on certain types of weeds. The highest sunflower seed yield of 1.40 t/ha, oil yield of 0.69 t/ha was obtained in the option with the use of herbicide with d.r. imazapyr (15 g/l) + imazamox (33 g/l), and the highest oil content of 50.10% in the option with tribenuron-methyl (750 g/kg).