Evaluation of Corn Gluten Meal for Weed Control In Cowpea

Cowpea is important to a diversity of farmers in the U.S. central plains.  Current weed control practices for cowpea production typically involve the use of synthetic herbicides.  Increasing interest in organic crop production in the region creates a need for alternative weed control techniques that are consistent with the requirements of the USDA National Organics Program.  Corn gluten meal (CGM), a by-product of the corn milling process, has been shown to control weeds at the time of seed germination.  Its use as a weed control material has already been explored for several vegetables.  The current project evaluates the use of CGM in cowpea as part of a weed management program that includes mechanical cultivation and manual weed removal measures.  In 2006 and 2008 cowpea was direct seeded at Bixby, Oklahoma on a Severn very fine sandy loam soil.  Immediately following seeding CGM was applied at either 2178 or 6534 lbs / acre to the soil surface.  At each CGM rate, applications were made using two methods: a solid band over the row (solid) or a band that had a narrow strip just above the seed row that remained untreated (banded).  Another treatment (herbicide) used the herbicides Dual Magnum (0.75 lb ai/acre) and Pursuit (0.063 lb ai/acre) applied preemergence.  A sixth treatment did not receive herbicide or CGM (weedy).  These treatments were cultivated and hoed once crop growth and weed size were sufficient to perform these procedures.  In a seventh treatment, (weeded), weeds were removed manually while very small throughout the course of the study.  Prior to performing the cultivation and hoeing procedures, percent weed control was estimated for all CGM and herbicide treatments.  The time requirement for cultivation and hoeing was determined for each treatment.  Plots were harvested at maturity to estimate cowpea yields.  Yields did not differ significantly among treatments for either year for the study.