Sensitivity of weeds to Lumax herbicide under growing conditions with pre- and post-emergent application was studied. Evaluation of biological and economic efficiency of Lumax herbicide at different terms of use was given. The studies were conducted in 2020–2022 in the Primorsky Territory. The soil of the experimental plots is meadow-brown podzolized, containing 3–4% of humus in the arable horizon. The agricultural technique is based on no-tillage technology. The forecrop was soybeans. The hybrid population P 8521 was used in the field experiments. The sensitivity of 16 weed species was studied when used in pre-emergence applications and 18 when used on vegetative plants in the early stages of their development. Visual observations of plant development after treatments with Lumax herbicide were made. At soil application, the preparation inhibited the germination of lamb’s-quarters, pigweed, hemp nettle, barnyard grass, bur beggar-ticks, yellow-foxtail grass and green bristle grass, field milk thistle and yellow thistle. Sprouts of China jute, common persicaria and copper leaf were completely dead by the 7th day. Moderate sensitivity was shown by ragweed, hairy cupgrass, and dayflower. Trailing hollyhock proved to be resistant to this herbicide. When using Lumax on vegetating plants, 17 species were highly sensitive, with only hairy cupgrass being relatively sensitive. In field experiments in the grain maize crop, weed infestation averaged 531 plants/m2 with a total above ground mass of 3279 g/m2. The herbicide was applied at three times: before sprouting, in the phases of the 2-3rd and 5th-6th of corn leaves. There were advantages and disadvantages with each term of its use. At preemergence, it more actively suppressed annual grasses, while at late (the 5th-6th leaf phase) it suppressed perennial dicotyledons. Application of the herbicide in the 2nd-3rd corn leaf phase showed approximately equal effect on the weeds. Lumax effectively eliminated dayflower and annual dicotyledonous weeds. Regardless of the timing of application, it contributed to saving 29.8-36.7 co of corn grain/ha.
