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United States Department of Agriculture

Agricultural Research Service

Research Project: ORGANIC AND REDUCED INPUT FRESH MARKET SPECIALTY CROP PRODUCTION SYSTEMS FOR THE SOUTHERN GREAT PLAINS Title: Pelargonic acid - a potential organic aquatic herbicide for duckweed management

Author
item Webber, Charles

Submitted to: Journal of Environmental Monitoring and Restoration
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 20, 2010
Publication Date: November 2, 2010
Citation: Webber III, C.L. 2009. Pelargonic acid - a potential organic aquatic herbicide for duckweed management. Journal of Environmental Monitoring and Restoration. 6:174-180.

Interpretive Summary: Duckweed (Lemna spp.) is a natural food source for fish and fowl, and is invasive because it is easily transported to new locations by transient water fowl and quickly exploits suitable environments once delivered. Duckweed uncontrolled can result in oxygen depletion, fish kills, and death of submerged aquatic plants. Greenhouse research was conducted at Lane, OK, to determine the feasibility of using pelargonic acid to control duckweed. Pelargonic acid is a fatty acid naturally occurring in many plants and animals, and present in many foods we consume. AU720 (65% pelargonic acid, BioSafe Systems LLC) is a potential organic herbicide under development for aquatic weed control. Treatments included dilutions of 0.0006%, 0.0015%, 0.006%, and 0.015% v/v and a control (0% v/v) with 8 replications and the experiment was repeated twice. Duckweed (7.5 g) was added to 400 mL beakers containing 250 mL of the diluted solutions and the beakers placed in a greenhouse. Visual ratings were collected 1, 3, and 5 days after treatment. Pelargonic acid was phytotoxic at all dilutions. Duckweed control was less than acceptable (less than 10% control) at 0.0006% and 0.0015%, inconsistent at 0.006% (3 to 99% control), but very affective (96 to 100% control) at 0.015%. If used at 0.015% v/v, pelargonic acid (AU720) has potential as a duckweed management tool. Additional research should investigate the impact of different application systems for delivering the herbicide to the target plants.

Technical Abstract: Duckweed (Lemna spp.) are small, free floating aquatic plants that flourish on stagnant, or slow moving, water surfaces throughout the continental U.S. Members of the genus are among the smallest flowering plants, providing food for fish and fowl, but their aggressive growth and invasive habit make them aquatic weeds which uncontrolled can result in oxygen depletion, fish kills, and death of submerged aquatic plants. Greenhouse research was conducted at Lane, OK, to determine the feasibility of using pelargonic acid to control duckweed. Pelargonic acid is a fatty acid naturally occurring in many plants and animals, and present in many foods we consume. AU720 (65% pelargonic acid, BioSafe Systems LLC) is a potential organic herbicide under development for aquatic weed control. Treatments included the 0.0006%, 0.0015%, 0.006%, and 0.015% v/v and a control (0% v/v) with 8 replications and the experiment was repeated twice. Duckweed (7.5 g) was added to 400 mL beakers containing 250 mL of the diluted solutions and the beakers placed in a greenhouse. Visual ratings were collected 1, 3, and 5 days after treatment. Pelargonic acid was phytotoxic at all dilutions. Duckweed control was less than acceptable (less than 10% control) at 0.0006% and 0.0015%, inconsistent at 0.006% (3 to 99% control), but very affective (96 to 100% control) at 0.015%. If used at 0.015% v/v, pelargonic acid (AU720) has potential as a duckweed management tool.

Last Modified: 9/10/2014
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