Identifying herbicides to manage weeds in a buckwheat cover crop and for the control of volunteers

Abstract

Buckwheat (Fagopyrum esculentum) is a fast-growing plant that quickly produces a dense groundcover. The utilization of buckwheat as a cover crop in vegetable production could be beneficial to Georgia producers, however for successful adoption, weed control in the cover crop coupled with control of buckwheat volunteers must be achievable. A preemergence (PRE) and a postemergence (POST) experiment were each conducted three times in Ty Ty, GA (2020–2021) addressing these objectives. In the PRE study, acetochlor at 0.56 lb ai acre⁻¹ injured buckwheat up to 16% without negatively influencing growth, suggesting potential for use in buckwheat for weed control. Flumioxazin, fomesafen, halosulfuron, ethalfluralin and S-metolachlor lacked adequate buckwheat safety. However, flumioxazin at 0.05 lb ai acre⁻¹, fomesafen at 0.19 lb ai acre⁻¹, and halosulfuron at 0.02 lb ai acre⁻¹ were identified as effective options to manage volunteer plants, as control exceeded 80%. In the POST experiment, buckwheat injury from 2,4-D, clethodim, dicamba, glufosinate, glyphosate, halosulfuron, linuron, paraquat, and prometryn was evaluated, and when considering all evaluation parameters, paraquat (0.50 lb ai acre⁻¹) was the most effective option for the control of buckwheat. This was followed by glufosinate (0.59 and 1.17 lb ai acre⁻¹) and glyphosate (1.20 and 2.40 lb ai acre⁻¹). For potential applications over buckwheat for weed management, clethodim (0.12 lb ai acre⁻¹) was the only POST herbicide that provided adequate crop safety.