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Title: Pelargonic acid: Rate, adjuvants, and application timing

Author
item Webber Iii, Charles
item SHREFLER, JAMES - OSU, LANE, OK

Submitted to: Oklahoma Agriculture Experiment Station Departmental Publication
Publication Type: Experiment Station
Publication Acceptance Date: 5/15/2006
Publication Date: 6/1/2006
Citation: Webber III, C.L., Shrefler, J.W. 2006. Pelargonic acid: Rate, adjuvants, and application timing. 2005 Vegetable Weed Control Studies, Oklahoma State University, Division of Agricultural Sciences and Natural Resources, Department of Horticulture and Landscape Architecture. Stillwater, OK. MP-162, p. 27.

Interpretive Summary:

Technical Abstract: Pelargonic acid is a fatty acid that occurs naturally in many plants and animals, and is present in many foods we consume. Producers and researchers are interested in pelargonic acid as a broad-spectrum post-emergence or burn-down herbicide. The objective of this research was to determine the effect of pelargonic acid (nonanoic acid) concentration, adjuvants, and application timing on weed control efficacy as a burn-down herbicide. Field research with pelargonic acid was conducted in southeast Oklahoma (Lane, OK, Atoka County) during the 2005 growing season (June - August). One month prior to spraying the weed control treatments, the land was cultivated to kill existing weeds and provide a uniform seed bed for new weed growth. The factorial weed control treatments included three application concentrations of Scythe (57.0% pelargonic acid) applied at 3, 6.5, and 10%, three adjuvants (none, orange oil, and non-ionic surfactant), and two application dates. All herbicide treatments were applied with an application volume of 100 gpa to seedling weeds. The experiment had a high weed density with multiple species of grass and broadleaf weeds. Weed control across species increased as the herbicide concentrations increased from 0 to 10%. At all concentrations applied, pelargonic acid produced greater weed control for a longer time period for the broadleaf weeds than for the grass weeds. Visual damage to the weeds was often apparent within a few hours after application. There was a significant increase in weed control when applied to the younger weeds. In this research, pelargonic acid was effective in controlling both broadleaf and grass weeds as a burn-down herbicide, although crabgrass was tougher to control. Additional research will investigate pelargonic acid application methods and weed control efficacy in relationship to controlling additional weed species, and integrating its use into cropping systems.