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United States Department of Agriculture

Agricultural Research Service

Research Project: Integrated Crop, Soil, and Water Management Systems for Sustainable Production of Sugarcane for Bioenergy Feedstock

Location: Sugarcane Research Unit

Title: Sequential applications of pelargonic acid for weed control in squash

Authors
item Webber, Charles
item Shrefler, James -
item Brandenberger, Lynn -
item Davis, Angela -
item Taylor, Merritt -

Submitted to: Proceedings of Horticultural Industry Show
Publication Type: Proceedings
Publication Acceptance Date: January 18, 2013
Publication Date: June 13, 2013
Citation: Webber III, C.L., Shrefler, J.W., Brandenberger, L.P., Davis, A.R., Taylor, M.J. 2013. Sequential applications of pelargonic acid for weed control in squash. 2013 Proceedings of Horticultural Industry Show, January 11-12, 2013, Fort Smith, Arkansas. p. 152-157.

Interpretive Summary: Weed control can be a constant challenge, especially when dealing with the limited herbicide options available to organic vegetable producers. Organic squash (Cucurbita pepo L.) producers need appropriate herbicides that can effectively provide weed control throughout the production season. A potential solution to increase weed control for larger weeds and decrease squash injury is the use of multiple/consecutive 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 into raised 3-ft centered beds. The experiment included two herbicides, AXXE® (65% pelargonic acid) and Scythe® (57% pelargonic acid), applied post-directed at 75 gallons per acre at 4 rates (1.5, 3, 5, and 10% by volume). 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% by volume treatments. Weed control (total, broadleaf, and grass) increased as the application rates increased, producing a minimum of 99% control 1 day after the initial herbicide treatment for the 10% volume application rate for each herbicide. In general, both herbicides produced similar results for similar applications rates with some variation among treatments for the different sampling dates. The 5% by volume sequential application of either herbicide produced equivalent weed control and yields with less seasonal squash injury than the one time 10% by volume application. The 5% by volume 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.

Technical Abstract: Weed control can be a constant challenge, especially when dealing with the limited herbicide options available to organic vegetable producers. Organic squash (Cucurbita pepo L.) producers need appropriate herbicides that can effectively provide weed control throughout the production season. Although corn gluten meal has shown promise as an early-season pre-emergent organic herbicide in squash production, uncontrolled weeds can inflict yield reductions by the end of the growing season. 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 into raised 3-ft centered beds. The experiment included two herbicides, AXXE® (65% pelargonic acid) and Scythe® (57% pelargonic acid), applied post-directed (75 gpa, 8004 spray tips, 0.40 gpm) 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. The experiment also included an untreated weedy-check and an untreated weed-free check and four replications. Weed control (total, broadleaf, and grass) increased as the application rates increased, producing a minimum of 99% control 1 day after initial treatment (DAIT) for the 10% v/v rate for each herbicide. In general, both herbicides produced similar results for similar applications rates with some variation among treatments for the different sampling dates. The single application of each herbicide at 10% v/v performed similarly across weed control rates (12 to 41 DAIT) to the sequential application of 5% v/v. These results provide the producer with the option to apply the herbicides in a single high rate or make two judicial sequential applications. In general, all the herbicide applications produced as good or greater yields than the weedy-check.

Last Modified: 8/22/2014
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