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Title: Potential organic herbicides for squash production: Pelargonic acid herbicides AXXE® and Scythe®

item Webber Iii, Charles
item SHREFLER, JAMES - Oklahoma State University
item BRANDENBERGER, LYNN - Oklahoma State University
item DAVIS, ANGELA - Harris Moran Seed Company

Submitted to: Experiment Station Bulletins
Publication Type: Experiment Station
Publication Acceptance Date: 3/15/2012
Publication Date: 6/1/2012
Citation: Webber III, C.L., Shrefler, J.W., Brandenberger, L.P., Davis, A.R. 2012. Potential organic herbicides for squash production: Pelargonic acid herbicides AXXE® and Scythe®. 2011 Vegetable Weed Control Studies. Oklahoma State University, Division of Agricultural Sciences and Natural Resources, Department of Horticulture & Landscape Architecture. Stillwater, OK. MP-162. p. 10-12.

Interpretive Summary:

Technical Abstract: Organic squash (Cucurbita pepo L.) producers need appropriate herbicides that can effectively provide season-long weed control. Although corn gluten meal has shown promise as an early-season pre-emergent organic herbicide in squash production, any uncontrolled weeds can inflict serious yield reductions by the end of the growing season. Previous research with post-emergence organic contact herbicides determined that these herbicides must be applied to very young/small weeds if acceptable weed control is expected. A potential solution to increase weed control efficacy on larger weeds and decrease squash injury is the use of multiple/sequential post-directed herbicide applications (herbicides sprayed at the base of the crop rather than over-the-top). Research was conducted in southeast Oklahoma (Atoka County, Lane, OK) to determine the impact of sequential post-directed applications of potential organic herbicides on weed control efficacy, crop injury, and yields. Yellow squash cv. 'Enterprise' was direct-seeded on June 27, 2011, into raised 91-cm centered beds. The experiment included two herbicides, AXXE® (65% pelargonic acid) and Scythe® (57% pelargonic acid), applied post-directed (75 gpa, 8004, 0.40 gpm, July 14) at 4 rates (1.5, 3, 5, and 10% v/v). Eleven days after the initial herbicide treatment, a second/sequential post-directed application was applied for each herbicide for the 1.5, 3, and 5% v/v treatments (75 gpa, 8004, 0.40 gpm) on July 25. The experiment also included an untreated weedy check and an untreated weed-free check and 4 replications. The 5% v/v sequential application of either herbicide produced equivalent weed control and yields with less seasonal squash injury than the one-time 10% v/v application. The 5% v/v sequential applications provide additional flexibility in the timing of the weed control treatments. Additional research should focus on fine-tuning the herbicide application to control specific weeds at various maturity levels and sizes.