Technical efficiency of herbicide tank mixtures under sunflower cultivation in the northern Steppe of Ukraine

At the current weed infestation level of chernozem, it is almost impossible to grow sunflowers without the regulated use of the most effective herbicides with different action spectrum on weeds. It was established that tank mixtures of ethametsulfuron-methyl herbicides (750 g/kg) – 25 g/ha + aclonifen (600 g/l) – 1.2 l/ha + surfactant Trend 90 – 300 ml/ha and ethametsulfuron-methyl (750 g/kg) – 25 g/ha + aclonifen (600 g/l) – 1.5 l/ha + surfactant Trend 90 – 300 ml/ha provided the highest technical efficiency and the lowest air-dry mass of weeds in the oilseed agrocenosis. Their technical efficiency was 61.2–65.8%. Almost all variants of herbicide tank mixtures showed a high phytotoxic effect on green amaranth (Amarantus retroflexus L.) – 51-61%, common ragweed (Ambrosia artemisiifolia) – 52–76%, field bindweed (Convolvulus arvensis) – 100%, yellow foxtail (Setaria pumila L.) was the less controlled – 21– 31%. The variants with the application of herbicide tank mixtures of ethametsulfuron-methyl (750 g/kg) – 25 g/ha + aclonifen (600 g/l) – 1.2 l/ha + surfactant Trend 90 – 300 ml/ha showed the highest indicators of the yield structure elements, here the 1000 seed weight was 73.1 g at a maximum basket diameter of 31.5 cm. These indicators were less in 1.2–1.7 times for other studied variants with the herbicide tank mixtures. When application of the tank mixtures of ethametsulfuron-methyl (750 g/kg) – 25 g/ha + aclonifen (600 g/l) – 1.2 l/ha + surfactant Trend 90 – 300 ml / ha and ethametsulfuron -methyl (750 g/kg) – 25 g/ha + aclonifen (600 g/l) – 1.5 l/ha + surfactant Trend 90 – 300 ml/ha, it was obtained the maximum yield of sunflower seeds 2.15 and 2.07 t/ha, respectively. Other variants with herbicides and their tank mixtures had significantly lower yield of sunflower seeds – by 23–27 %. Key words: sunflower, weeds, herbicides, tank mixes, yield, technical efficiency