Green bristle-grass and yellow foxtail in the agrocenoses of the Primorsky Territory and the search for effective soil herbicides to control them in soybean crops

In the period from 2015 to 2024, the occurrence and abundance of green bristle-grass Setaria viridis (L.) Beauv. and yellow foxtail Setaria pumila (Poir.) Schult. were studied in the agrocenoses of the Primorsky Territory. Both species have been consistently present as weeds in soybean, corn, and early grain crops for 10 years, reaching high levels of occurrence (60–91%) and abundance (9.8–17.9 pcs/m 2 ) in some years. To control these species in soybean crops, the most important crop for the south of the Far East, a search has been carried out for the herbicides with soil activity and capable of effectively protecting it at early stages of growth and development. For this purpose, in the conditions of a vegetation house in 2021–2022, the sensitivity of two types of bristle was studied to seven preparations approved for the protection of soybeans from weeds: Pledge, WP (active ingredient (a.i.) flumioxazine, 500 g/kg), Zenkor Ultra, SC (a.i. metribuzin, 600 g/l), Kommand, EC (a.i. klomazon, 480 g/l), Gezagard, SC (a.i. promethrin, 500 g/l), Gardo Gold, SC (a.i. C-metolachlor + terbutylazine, 312.5 + 187.5 g/l), Dual Gold, EC (a.i. C-metolachlor, 960 g/l), and Proponite, EC (a.i. propizochlor, 720 g/l). Herbicides in the maximum allowable rates were applied to the soil surface in vessels a day after sowing the weeds. In terms of reducing the crude aboveground biomass of both species of bristle grass, the maximum efficiency (96-100%) was demonstrated by Proponite at a rate of 3.0 l/ha, Dual Gold 1.6 l/ha, Gardo Gold 4.5 l/ha, and Gezagard 3.5 /ha.