Volunteer Buckwheat Control In Wheat

Buckwheat is a short-duration crop that readily drops seed before harvest, often resulting in volunteer buckwheat plants in the following crop. Buckwheat can act as a potent allergen, and some importers of U.S. wheat have a near-zero tolerance for buckwheat in grain shipments. Field studies were conducted near Pasco, WA under irrigated conditions and near Huntley, MT under dryland conditions to evaluate herbicide efficacy for buckwheat control in spring wheat. Irrigated studies included both early postemergence herbicide applications and late postemergence applications, the latter of which were applied with a sprayer designed to simulate application via chemigation. Only early postemergence herbicide treatments were evaluated in the dryland studies. With irrigation, visible control of buckwheat averaged 95% when an early postemergence herbicide application was made followed by a late postemergence herbicide application at the boot stage, but averaged 84% control when only an early postemergence application was made. No herbicide treatment eliminated buckwheat seed contamination of wheat grain from the irrigated studies. Bromoxynil + MCPA ester and fluroxypyr + bromoxynil provided superior visible control of volunteer buckwheat in dryland spring wheat in 2015 and 2016, and eliminated buckwheat seed contamination in the harvested grain in 2015. Dry conditions in 2016 prevented buckwheat seed production. The inability to eliminate buckwheat contamination in irrigated spring wheat with herbicides suggests that other approaches are needed. Foremost of these is not planting wheat for at least one or possibly two years following buckwheat harvest.