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Title: Alternative weed control-an update on USDA research

Author
item Webber Iii, Charles

Submitted to: Proceedings of Horticultural Industry Show
Publication Type: Proceedings
Publication Acceptance Date: 2/4/2005
Publication Date: 4/1/2005
Citation: Webber III, C.L. 2005. Alternative weed control-an update on USDA research. Proceedings of the 24th Annual Horticulture Industries Show. p. 40-42.

Interpretive Summary: Alternative weed control methods represent a significant portion of the USDA, ARS weed control research at the South Central Agricultural Research Laboratory at Lane, OK (Atoka County, southeast Oklahoma). The research investigates a wide range of management practices for weed control in vegetable crops. Insights learned from one production system often provide insights and applications for other production systems. Alternative weed control materials investigated during the 2004 growing season included corn gluten meal (CGM), vinegar (acetic acid), and pelargonic acid. The objective of the CGM research was to develop a method to uniformly apply CGM to the soil surface in either a solid (broadcast) or banded pattern. Equipment was developed and evaluated for the application of two CGM formulations (powdered and granulated), three application rates [5, 10, and 15 lb/100 ft**2 (250, 500, and 750 g/m**2)], and two application configurations (solid and banded). These evaluations demonstrated the feasibility of using equipment, rather than manual applications, to apply CGM to raised beds for organic weed control purposes. Vinegar has been identified as a potential organic herbicide, yet more information is needed to determine influence of acetic acid concentration, application volume, and use of additives (adjuvants) on weed control. The factorial experimental design included vinegar at three acetic acid concentrations (0, 5, and 20 %), two sprayer application volumes (20 and 100 gpa), three adjuvants (none, orange oil, and canola oil), and two weedy-checks. When averaged across the other actors, weed control increased as the application volume or vinegar concentration increased. Pelargonic acid is a fatty acid naturally occurring in many plants and animals, present in many foods we consume, and has potential as an affective herbicide. Field research was conducted to determine the effect of pelargonic acid (nonanoic acid) concentration on weed control efficacy as a burn-down herbicide. In this initial trial, pelargonic acid was effective in controlling both broadleaf and grass weeds as a burn-down herbicide. Initial research in 2004 with the corn gluten meal applicator, vinegar, and pelargonic acid all demonstrated promise and potential usefulness for alternative weed control. Research in 2005 will repeat the 2004 research studies and also investigate other alternative materials that have potential use in controlling weeds in an environmentally friendly manner for organic, sustainable, and conventional vegetable production systems.

Technical Abstract: Weed control research at the USDA, ARS, South Central Agricultural Research Laboratory at Lane, OK investigates a wide range of management practices for weed control in vegetable crops. Alternative weed control materials investigated during the 2004 growing season included corn gluten meal (CGM), vinegar (acetic acid), and pelargonic acid. Corn gluten meal is an environmentally friendly material that has demonstrated ability to decrease seedling development and plant survival by inhibiting root and shoot development. Equipment was developed and evaluated for the application of two CGM formulations (powdered and granulated), three application rates [5, 10, and 15 lb/100 ft**2 (250, 500, and 750 g/m**2)], and two application configurations (solid and banded). These evaluations demonstrated the feasibility of using equipment, rather than manual applications, to apply CGM to raised beds for organic weed control purposes. Vinegar has been identified as a potential organic herbicide, yet more information is needed to determine influence of acetic acid concentration, application volume, and use of additives (adjuvants) on weed control. The factorial experimental design included vinegar at three acetic acid concentrations (0, 5, and 20 %), two sprayer application volumes (20 and 100 gpa), three adjuvants (none, orange oil, and canola oil), and two weedy-checks. When averaged across application volumes (20 and 100 gpa) and adjuvants (none, orange oil, and canola oil), weed control increased for all species as acetic acid concentrations increased from 5 to 20%. When averaged across acetic acid concentrations and adjuvants, weed control increased as application volumes increased from 20 to 100 gpa. Pelargonic acid is a fatty acid naturally occurring in many plants and animals, present in many foods we consume, and has potential as an affective herbicide. Field research was conducted to determine the effect of pelargonic acid (nonanoic acid) concentration on weed control efficacy as a burn-down herbicide. In this initial trial, pelargonic acid was effective in controlling both broadleaf and grass weeds as a burn-down herbicide. Initial research in 2004 with the corn gluten meal applicator, vinegar, and pelargonic acid all demonstrated promise and potential usefulness for alternative weed control. These research studies will be repeated and expanded during the 2005 growing season.