Broadleaf weed control and white clover response to florpyrauxifen-benzyl + 2,4-D and common pasture herbicides

Abstract

The combination of florpyrauxifen-benzyl + 2,4-D is a new pre-packaged herbicide mixture for use in pastures and hayfields in the United States. Unlike many other pasture herbicides, florpyrauxifen-benzyl + 2,4-D is reported to preserve white clover. However, there is limited research on the efficacy of florpyrauxifen-benzyl + 2,4-D on common weed species as well as the level of tolerance of white clover. Field trials were conducted across Virginia in 2018-20 to evaluate control of various broadleaf weeds with florpyrauxifen-benzyl + 2,4-D compared to other commonly used herbicides as well as field and greenhouse studies assessing white clover tolerance. Weed species evaluated included: bulbous buttercup, Canada thistle, horsenettle, and broadleaf plantain. Florpyrauxifen-benzyl + 2,4-D provided 75 to 99% control of all weeds 90 days after application except for horsenettle (56%), while causing the least white clover injury of any herbicide treatment evaluated. Across treatments, spring herbicide applications resulted in greater bulbous buttercup control compared to fall applications, but florpyrauxifen-benzyl + 2,4-D resulted in greater than 81% control from both application timings. There were no differences in above ground biomass between white clover varieties, however all herbicides reduced white clover biomass compared to the nontreated. This research suggests that florpyrauxifen-benzyl + 2,4-D can improve overall forage quality by controlling broadleaf weeds in mixed grass-legume stands while preserving white clover.