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Title: Corn gluten meal for weed control in cowpea

Author
item BRANDENBERGER, LYNN - Oklahoma State University
item SHREFLER, JAMES - Oklahoma State Experiment Station
item Webber Iii, Charles
item CARRIER, LYNDA - Oklahoma State University
item GOODSON, TONY - Oklahoma State Experiment Station
item HAVENER, ROBERT - Oklahoma State University
item ADAMS, ROBERT - Oklahoma State University

Submitted to: Extension Publications
Publication Type: Experiment Station
Publication Acceptance Date: 4/15/2009
Publication Date: 5/5/2009
Citation: Brandenberger, L.P., Shrefler, J.W., Webber III, C.L., Carrier, L.K., Goodson, T.L., Havener, R.L., Adams, R.J. 2009. Corn gluten meal for weed control in cowpea. In: Brandenberger, L., Wells, L., editors. 2008 Vegetable Weed Control Studies. Oklahoma State University, Division of Agricultural Sciences and Natural Resources, Department of Horticulture & Landscape Architecture. Stillwater, OK. MP-162 p. 6.

Interpretive Summary: Cowpea is a major vegetable crop in Oklahoma. It is utilized as a processing crop by the canning industry and as a fresh market crop. Traditionally weed control in this crop is with preemergence and some postemergence herbicides, but recently fresh market producers have shown an interest in examining possible organic means of weed control. The objective of this study was to determine the potential for weed control using organic practices and products, with comparison to traditional herbicides. Cowpea (cv. Empire) was direct-seeded on July 17, 2008 at Bixby, OK. Herbicide and corn gluten meal (CGM) treatments were applied on July 17, 2008. Each plot consisted of four rows on 36 in-row centers with rows twenty feet in length. CGM was applied at 2178 and 6534 lb/a as banded or broadcast applications. The synthetic herbicide was a tank-mixed application of Dual Magnum (0.75 lb ai/acre) and Pursuit (0.063 lb ai/a). All organic treatments, weeded checks and unweeded checks were cultivated on Aug. 7, 2008 and hand weeded on Aug. 7, 27, and Sept. 28. All plots were machine harvested on Sept. 27, 2008. Costs involved in controlling weeds in the study included herbicides, hand weeding, and tractor cultivation. The synthetic herbicide treatment used less time and cost compared to all other treatments. Hand weeding time ranged from 8 hr/a for the Dual Magnum-Pursuit treatment to 33 hr/a for the weed-free check. For the hand weeding, corn gluten meal treatments reduced production costs compared to the weed-free hand weeded control. The time and cost for hand weeding the corn gluten meal treatments was greater than the Dual Magnum-Pursuit treatment. Yield ranged from 1254 lb/a for the weedy-check to 1760 lb/a for the lowest corn gluten meal rate (2178 lb/a) with the broadcast application. Further research should investigate weed control efficacy and economic impact of organic postemergence herbicides used in conjunction with corn gluten meal.

Technical Abstract: Cowpea, a major crop in Oklahoma, is produced for the fresh market and canning industry. Synthetic preemergence and postemergence herbicides are the primary weed control method in conventional (non-organic) production systems. Organic weed control in organic cowpea production includes obstacles while striving to control costs. The objective of this study was to determine the potential for weed control using organic practices and products, with a comparison to traditional herbicides. Cowpea (cv. Empire) was direct-seeded on July 17, 2008 at Bixby, OK. Herbicide and corn gluten meal (CGM) treatments were applied on July 17, 2008. Each plot consisted of four rows on 36 in-row centers with rows twenty feet in length. CGM was applied at 2178 and 6534 lb/a as a banded or broadcast application. The synthetic herbicide was a tank-mixed application of Dual Magnum (0.75 lb ai/acre) and Pursuit (0.063 lb ai/a). All organic treatments, weeded checks and unweeded checks were cultivated on Aug. 7, 2008 and hand weeded on Aug. 7, 27, and Sept. 28. All plots were machine harvested on Sept. 27, 2008. Costs involved in controlling weeds in the study included herbicides, hand weeding, and tractor cultivations. The synthetic herbicide treatment involved less time and cost compared to all other treatments. Hand weeding time ranged from 8 hr/a for the Dual Magnum-Pursuit treatment to 33 hr/a for the weed-free check. For the hand weeding, the corn gluten meal treatments reduced production costs compared to the weed-free hand weeded control. The time and cost for hand weeding the corn gluten meal treatments is significantly greater than the Dual Magnum-Pursuit treatment. Yield ranged from 1254 lb/a for the weedy-check to 1760 lb/a for the lowest corn gluten meal rate (2178 lb/a) with the broadcast application. Further research should investigate weed control efficacy and economic impact of addition organic postemergence herbicides used in conjunction with corn gluten meal.