Weed control with pelargonic acid (2004) Lane, Oklahoma

Authors: Webber Iii, Charles; SHREFLER, JAMES - OSU, LANE, OK; LANGSTON, VERNON - DOW, HOUSTON, TX

Submitted to: Oklahoma Agriculture Experiment Station Departmental Publication
Publication Type: Experiment Station
Publication Acceptance Date: 1/27/2005
Publication Date: 1/31/2005
Citation: Webber III, C.L., Shrefler, J.W., Langston, V.B. 2005. Weed control with pelargonic acid (2004) Lane, Oklahoma. In: Brandenberger, L., Wells, L. editors. 2004 Vegetable Trial Report. Oklahoma State University, Division of Agricultural Sciences and Natural Resources, Department of Horticulture and Landscape Architecture, Stillwater, Oklahoma. MP-162. p. 32-33.

Interpretive Summary: Vegetable producers and researchers are looking for organic chemicals that will be environmentally friendly and affective herbicides. 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 in southeast Oklahoma (Lane, OK, Atoka County) to determine the effect of pelargonic acid (nonanoic acid) concentration on weed control efficacy as a burn-down herbicide. One month prior to spraying the weed control treatments the land was cultivated to kill the existing weeds and provide a uniform seed bed for new weed growth. The research involved 3 weed control treatments and a weedy-check with 3 replications. The weed control treatments included applications of Scythe (57.0% pelargonic acid) applied at 3, 6.5, and 10% with a spray volume of 100 gpa to the seedling weeds. Weed ratings were collected on July 20 (4 DAT), July 26 (10 DAT), and August 3 (18 DAT) 2004. The experiment had a high weed density with multiple species of grass and broadleaf weeds. The weeds present at spraying included large crabgrass (Digitaria sanguinalis (L.)), goosegrass (Eleusine indica L.), carpetweed (Mollugo verticillata L.), cutleaf evening primrose (Oenothera laciniata Hill), spiny amaranth (Amaranthus spinosus), Eclipta (Eclipta prostrata L.), and yellow nutsedge (Cyperus esculentus). Weed control across species increased as 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 the grass weeds. Visual damage to the weeds was often apparent within a few hours after application. In this initial trial, pelargonic acid was effective in controlling both broadleaf and grass weeds as a burn-down herbicide. Additional research will investigate pelargonic acid application methods and weed control efficacy in relationship to controlling additional weed species, different weed maturities, and integrating its use into cropping systems.

Technical Abstract: Pelargonic acid is a fatty acid naturally occurring in many plants and animals, and present in many foods we consume. Producers and researchers are interested in pelargonic acid as a broad-spectrum post-emergence or burn-down herbicide. Field research was conducted in southeast Oklahoma (Lane, OK, Atoka County) to determine the effect of pelargonic acid (nonanoic acid) concentration on weed control efficacy as a burn-down herbicide. One month prior to spraying the weed control treatments the land was cultivated to kill the existing weeds and provide a uniform seed bed for new weed growth. The research involved 3 weed control treatments and a weedy-check with 3 replications. The weed control treatments included applications of Scythe (57.0% pelargonic acid) applied at 3, 6.5, and 10% with spray volume of 100 gpa to seedling weeds. Weed ratings were collected on July 20 (4 DAT), July 26 (10 DAT), and August 3 (18 DAT) 2004. The experiment had a high weed density with multiple species of grass and broadleaf weeds. The weeds present at spraying included large crabgrass (Digitaria sanguinalis (L.)), goosegrass (Eleusine indica L.), carpetweed (Mollugo verticillata L.), cutleaf evening primrose (Oenothera laciniata Hill), spiny amaranth (Amaranthus spinosus), Eclipta (Eclipta prostrata L.), and yellow nutsedge (Cyperus esculentus). Weed control across species increased as 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 the grass weeds. Visual damage to the weeds was often apparent within a few hours after application. The 6.5 and 10% applications controlled 100% of the broadleaf weeds throughout the 18 day evaluation period compared to a maximum of 90% (6.5% concentration) and 98% crabgrass control (10%) for 4 days after application. In this initial trial, 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, different weed maturities, and integrating its use into cropping systems.