Control of weeds in spring barley crops at different times of herbicide application

Weeds can significantly reduce the yield of spring barley, so research is relevant to determine the optimal time for applying herbicides based on modern active substances to control a wide range of weeds. In this regard, the purpose of this study is to determine the effectiveness of the Kvelex preparation based on new active substances halauxifen-methyl and florasulam in comparison with Lancelot 450 WG against annual and perennial dicotyledonous weeds during introduction into various phases of crop development and weeds in spring barley crops. The leading approaches to solving this problem are conducting field studies to determine the biological effectiveness of herbicide variants and statistical methods (dispersion, correlation) to determine the accuracy and reliability of experimental data. As a result of the conducted studies, it was found out that in the case of contamination with annual weeds Cenopodium album L., Polygonum convolvulus L., Amaranthus retroflexus L., herbicide application is best carried out in the cotyledon phase – the first pair of real weed leaves, which corresponds to the BBCH 18 phase of spring barley. This provided the highest efficiency against these species at 95.5% for Kvelex and 94.4% – Lancelot, 450 WG. But at this stage, the effectiveness against Cirsium arvense (L.) and Scop. Sonchus arvensis L. is up to 94% and 86.6%, respectively. However, thistles are significantly suppressed and do not compete for the crop in the future, which facilitated a significantly higher yield of spring barley (4.5 t/ha for applying Kvelex and 4.42 t/ha for using Lancelot 450 WG) compared to options where herbicides were applied in the BBCH 25-30 phases of the crop. The materials of the study are of practical value for farmers in choosing the phase of development of weeds and crops when applying herbicides in spring barley crops