Hairy Buttercup Control and White Clover Tolerance to Pasture Herbicides

Hairy buttercup (Ranunculus sardous Crantz) is a winter annual weed in southeastern U.S. pastures. Its potential toxicity and aggressive spring growth have made it a widespread concern among producers, especially in mixed grass-legume pastures. Few published studies have reported on its ecology or control. Furthermore, a lack of herbicide selectivity has historically been a problem when broadleaf weed control is needed in mixed grass-legume pastures. To address this issue, we compared multiple formulations of 2,4-D with imazethapyr, hexazinone, and aminopyralid + 2,4-D at December and February application timings for hairy buttercup control and white clover (Trifolium repens L.) tolerance. Dimethylamine, diethanolamine, and ester formulations of 2,4-D were effective in controlling hairy buttercup at 0.4 kg/ha. White clover cover was similar between all 2,4-D treated plots and the unsprayed control plots. Imazethapyr was also effective in controlling hairy buttercup. Hexazinone was not effective for hairy buttercup control and resulted in a considerable reduction in white clover. Aminopyralid + 2,4-D provided excellent hairy buttercup control but also eliminated clover cover. Herbicide treatments were very effective at both application timings. These studies indicate that hairy buttercup can be effectively controlled in mixed white clover/grass pastures with multiple herbicide options without reducing white clover populations.