Control of glyphosate-resistant horseweed with Group 4 herbicides in soybean

Abstract

Little information is available on the efficacy of Group 4 herbicides for glyphosate-resistant (GR) horseweed management in soybean. Five field research trials were established in growers’ fields from 2020 to 2021 to determine GR horseweed control with Group 4 herbicides applied pre-plant (PP) alone and in a mixture. There was minimal soybean injury (≤4%) with herbicides evaluated. Dicamba, 2,4-D, or halauxifen-methyl applied PP, controlled GR horseweed 92-96, 73-76, and 85-89%, respectively. The mixtures of dicamba + 2,4-D, dicamba + halauxifen-methyl, and dicamba + 2,4-D + halauxifen-methyl gave 97-99% control of GR horseweed, which were similar to dicamba applied alone. The mixture of 2,4-D + halauxifen-methyl gave 93-94% control of GR horseweed. Dicamba + saflufenacil controlled GR horseweed at 98%. Dicamba alone, dicamba + 2,4-D ester, dicamba + halauxifen-methyl, and dicamba + 2,4-D ester + halauxifen-methyl decreased GR horseweed density 97, 99, 99, and 98%, respectively, which were comparable to a 98% density reduction with dicamba + saflufenacil. Other herbicide treatments had no effect on GR horseweed density. Dicamba, 2,4-D, and halauxifen-methyl applied PP, decreased GR horseweed dry biomass by 99, 76, and 72%, respectively. The mixtures of dicamba + 2,4-D, dicamba + halauxifen-methyl, and dicamba + 2,4-D + halauxifen-methyl decreased GR horseweed dry biomass by 99-100%, which was comparable to a 99% dry biomass reduction with dicamba + saflufenacil. The mixture of 2,4-D + halauxifen-methyl decreased GR horseweed dry biomass by 94%. Soybean yield was decreased by 61% when GR horseweed was left uncontrolled. Results show that Group 4 herbicides that include dicamba applied PP can be very effective in managing GR horseweed in soybean.

Enhancing Wheat Yield and Economic Viability in Subtropical Rainfed Agriculture through Combined Herbicide Application

“…Economic analysis revealed that the combined herbicide treatment resulted in the highest economic returns compared to individual herbicide applications and the control. Despite the slightly higher initial investment associated with the combined herbicide treatment, the increased wheat yield and quality outweighed the additional costs, resulting in greater net profits for farmers [17][18][19].…”