Integrating Grazing with 2,4-D and Florpyrauxifen to Control Broadleaf Weeds and Maintain Red Clover Productivity in Grass-Legume Pastures

Integrating Grazing with 2,4-D and Florpyrauxifen to Control Broadleaf Weeds and Maintain Red Clover Productivity in Grass-Legume Pastures

In grass-legume pastures, 2,4-D-amine + florpyrauxifen-benzyl controls broadleaf weeds but red clover (Trifolium pratense L.) is eliminated. Grazing within a week prior to herbicide application is likely to reduce leaf surface area and may reduce red clover injury and maintain productivity. Experiments were conducted in 2020 and in 2021 to determine if red clover could be productive when 560 g ae ha-1 2,4-D-amine + 6.3 g ae ha^-1 of florpyrauxifen-benzyl with 1% v/v methylated seed oil applied in the spring was grazed before or after herbicide application. Grazing timings occurred 6, 4, or 2 days prior to herbicide application, the day of application, or 6 days after application. Grazing timing did not affect productivity or cover of red clover, white clover, forage grasses, broadleaf weeds, or annual grasses. In contrast, aboveground biomass of broadleaf weeds, red clover, and white clover was > 55, 56, and 44% less, respectively, in 2,4-D-amine + florpyrauxifenbenzyl treated pasture than nontreated pasture. Less clover and broadleaf weed biomass in herbicide treated pasture was associated with 16% more perennial grass biomass and no changes in total forage productivity. Results suggest that all grazing timings applied with 2,4-D-amine + florpyrauxifen-benzyl provided effective weed control that persisted more than 1 year with only partial injury to red clover populations. Grazing in concert with herbicide applications improves herbicide selectivity of preferentially grazed species, while improved from conventional standards practicality to producers is still unknown.