The aim of the work was to improve the regulation of the composition and density of forest stands by injecting herbicides and their mixtures into the trunks of hardwood trees to increase silvicultural efficiency, reduce the chemical and toxic load on forest ecosystems. The objects of research were individual trees of gray alder and aspen of vegetative origin in the pole stage in mixed stands. As a result of the analysis of domestic and foreign literature on the problem, promising herbicides for study were selected – tornado (aqueous solution, 360 g/l glyphosate in the form of isopropylamine salt) and arbonal (water-soluble concentrate, 250 g/l imazapyr) and field experiments were laid with selected herbicides. In four field experiments, the biological effectiveness of the action of herbicides and their mixtures on gray alder and aspen trees in mixed plantations was determined. As a result, the high efficiency of the herbicide arbonal at doses of 0.08 and 0.16 ml/tree, as well as mixtures of tornado (0.12–0.25 ml/tree) + arbonal (0.06–0.08 ml/tree) was established on gray alder. According to the effect on aspen, the most effective was the use of tornado 0.20 ml/tree and 0.55 ml/tree), arbonal (0.16 ml/tree) and mixtures of tornado (0.20 ml/tree) + arbonal (0.08 ml/tree) and tornado (0.25 ml/tree) + arbonal (0.06 ml/tree). Alder gray showed greater resistance to the applied herbicides in the year of treatment, but we should expect an increase in the effect of herbicides in the next growing season. It has been established that the use of herbicides tornado and arbonal, as well as their mixtures in various combinations, is very promising for the suppression of unwanted woody vegetation by injection in mixed stands.