Weed Infestation and Productivity of Oil Poppy Depending on the Use of Herbicide Protection

Studies were conducted to evaluate the effectiveness of using a mesotrione-based herbicide, 480 g/L (Egida, EC), by assessing its impact on crop infestation and the productivity of poppy plants. The work was carried out in 2023–2024 in the forest-steppe conditions of the Middle Volga region. The object of the research was the Issera oil poppy variety. The experiment included the following options: control (no treatment), manual weeding, and herbicide protection (Egida, EC, 0.25 L/ha). The treatment was carried out in the phase of six to eight true leaves of poppy plants. Weather conditions during the research years corresponded to insufficient moisture (HTC values of 0.55 and 0.83). In poppy crops, weeds were represented by late spring weeds (64.8%), early spring weeds (23.7%), winter weeds (7.2%), and perennial weeds (4.3%). The total wet weight of weeds decreased by 96.3% (compared to control) 20 days after manual weeding and by 80.5% 20 days after the treatment with herbicide. Before harvesting, these values were 91.5 and 88.7%, respectively. The protective effect of the drug lasts until the end of the poppy-growing season. Moreover, the efficiency of suppression of some weeds (chamomile, sow thistles) is 91.6–100%. Application of the herbicide leads to the seed yield increase similar to that after manual weeding (by 0.33 and 0.38 t/ha, respectively, over the control of 0.98 t/ha). The poppy productivity increases due to an increase in the elements of the crop structure: the number of capsules, the seed productivity of the plant, and the weight of 1000 seeds. Both manual weeding and application of the herbicide lead to a positive trend towards increasing the oil content of poppy seeds (0.50 and 0.31%, respectively, relative to the control).