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Title: Organic weed control in Cowpea: Summer 2006

Author
item BRANDENBERGER, LYNN - OSU, STILLWATER, OK
item SHREFLER, JAMES - OSU, LANE, OK
item Webber Iii, Charles
item TAYLOR, MERRITT - OSU, LANE, OK
item WELLS, LYNDA - OSU, STILLWATER, OK
item HAVENER, ROBERT - OSU, STILLWTER, OK
item Faulkenberry, Otis - Buddy

Submitted to: Extension Publications
Publication Type: Experiment Station
Publication Acceptance Date: 11/20/2006
Publication Date: 4/1/2007
Citation: Brandenberger, L.P., Shrefler, J., Webber III, C.L., Taylor, M., Wells, L.K., Havener, R., Faulkenberry, O.L. 2007. Organic weed control in Cowpea: Summer 2006. In: Brandenberger, L., Wells, L., editors. 2007 Vegetable Weed Control Studies. Oklahoma State University, Division of Agricultural Sciences and Natural Resources, Department of Horticulture & Landscape Architecture, Stillwater, Oklahoma. MP-164. p. 59-60.

Interpretive Summary:

Technical Abstract: Cowpea is a major vegetable crop within the state of Oklahoma. It is utilized as both a processing crop by the canning industry and as a fresh market crop for farmer’s and roadside markets. Traditionally weed control in this crop is primarily handled 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 and to provide a comparison between this and the traditional use of herbicides. The study was direct -seeded to cowpea (Empire cultivar) on June 15, 2006 at Bixby, OK. Herbicide and corn gluten meal (CGM) treatments were applied on June 16, 2006. Each plot consisted of four rows on 36 inch row centers twenty feet in length. CGM was applied at 2178 and 6534 lb/a as a banded or solid application. Synthetic herbicide application involved a tank-mixed application of Dual (0.75 lb ai/acre) and Pursuit (0.063 lb ai/a). All organic treatments, weeded checks and unweeded checks were cultivated on July 7, and 25, 2006 and hand weeded on July 7 and 28, and September 26, 2006. Plots receiving herbicide were hand weeded on September 26, 2006. All plots were machine harvested on October 2, 2006. Costs involved in controlling weeds in the study included herbicides, hand weeding, and tractor cultivations. Control of Palmer amaranth (pigweed) was highest for Dual + Pursuit and the weeded check compared to all other treatments. Dual (0.75 lb ai/acre) + Pursuit (0.063 lb ai/a) had 95% Palmer amaranth control, while the weeded check had 76% control. Carpetweed control was highest for Dual + Pursuit and the weeded check that had 96 and 71% control, respectively. CGM at 2178 lb/a applied solid and the weedy check had produced less weed control than Dual + Pursuit and the weeded check. Fewer carpetweed plants survived for Dual + Pursuit and the weeded check than in the CGM 2178 lb/a banded, CGM 6534 lb/a applied solid, and the weedy check treatments. Total costs were highest for CGM 2178 lb/a applied solid and the weedy check. CGM 2178 lb/a applied solid and the weedy check that had costs of $181.48 and $178.48 per acre, respectively compared to considerably lower costs of $75.48 and $90.73 per acre, respectively, for the weeded check and the herbicide treatment. Yield ranged from 261 to 508 lb/a, but no significance was observed among treatments, although a trend was observed. Both the weeded check and the herbicide treatment recorded the two highest yields at 508 and 468 lb/a, respectively.