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Title: Racer efficacy study, Fall 2007

Author
item BRANDENBERGER, LYNN - OSU, STILLWATER, OK
item Webber Iii, Charles
item SHREFLER, JAMES - OSU, LANE, OK
item WELLS, LYNDA - OSU, STILLWATER, OK

Submitted to: Extension Publications
Publication Type: Other
Publication Acceptance Date: 2/15/2008
Publication Date: 5/1/2008
Citation: Brandenberger, L.P., Webber III, C.L., Shrefler, J.W., Wells, L.K. 2008. Racer efficacy study, Fall 2007. In: Brandenberger, L., Wells, L., editors. 2007 Vegetable Trials Report, Oklahoma State University, Division of Agricultural Sciences and Natural Resources, Department of Horticulture and Landscape Architecture. Stillwater, OK. MP-164. p. 43-45.

Interpretive Summary: Weed competition is a primary concern for conventional and organic vegetable producers. Organic producers of vegetables have an even bigger challenge since their weed control tools are limited to cultural methods exclusively. Racer (ammonium nonanoate) is labeled for non-food use and efforts are currently underway to label it as a bio-herbicide for organically grown food crops. The objective of this study was to investigate different nozzles, rates of active ingredients, and overall rates of spray material for the control of endemic weed populations. The study was completed at the Oklahoma State University Vegetable Research station in Bixby, Oklahoma. Treatments included two nozzle types operated at recommended nozzle pressures (TeeJet XR8003 and TeeJet XR8005), three application concentrations of Racer (8.0, 11.2, and 14.4 lb ai/a), and two application volumes (35 and 70 gpa) for a total of 12 treatments. In general, Racer proved to be an effective contact herbicide for controlling the three weed species that were included in the study. The two higher rates of Racer (11.2 and 14.4 lbs ai/acre) were more effective than the 8.0 lbs ai/acre rate, although even the low rate resulted in higher levels of weed control than the untreated check. It appears that the overall spray application rate of 70 gpa probably diluted the active ingredient enough to reduce its effectiveness. Based upon the results, the authors would recommend further study to determine if similar results would be observed during a different season with different conditions, but would recommend examining rates of 11.2 and 14.4 lbs ai/acre and overall application rates of 35 gpa.

Technical Abstract: Weed control is a serious concern for commercial vegetable producers because of the limited number of herbicides available for this group of minor crops and the potential for crop injury. Organic producers of vegetables have an even bigger challenge since their weed control tools are limited to cultural methods exclusively. Racer (ammonium nonanoate) is labeled for non-food use and efforts are currently underway to label it as a bio-herbicide for organically grown food crops. The objective of this study was to investigate different nozzles, rates of active ingredients, and overall rates of spray material for the control of endemic weed populations. The study was completed at the Oklahoma State University Vegetable Research station in Bixby, Oklahoma. Treatments included two nozzle types operated at recommended nozzle pressures (TeeJet XR8003 and TeeJet XR8005), three application concentrations of Racer (8.0, 11.2, and 14.4 lb ai/a), and two application volumes (35 and 70 gpa) for a total of 12 treatments. In general, Racer proved to be an effective contact herbicide for controlling the three weed species that were included in the study. The two higher rates of Racer (11.2 and 14.4 lbs ai/acre) were more effective than the 8.0 lbs ai/acre rate, although even the low rate resulted in higher levels of weed control than the untreated check. It appears that the overall spray application rate of 70 gpa probably diluted the active ingredient enough to reduce its effectiveness. Based upon the results, the authors would recommend further study to determine if similar results would be observed during a different season with different conditions, but would recommend examining rates of 11.2 and 14.4 lbs ai/acre and overall application rates of 35 gpa.