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Title: Racer efficacy study, Fall 2008

Author
item BRANDENBERGER, LYNN - OSU, STILLWATER, OK
item Webber Iii, Charles
item SHREFLER, JAMES - OSU, LANE, OK
item CARRIER, LYNDA - OSU, STILLWATER, OK
item HAVENER, ROBERT - OSU, STILLWATER, OK
item ADAMS, ROBERT - OSU, STILLWATER, OK

Submitted to: Extension Publications
Publication Type: Experiment Station
Publication Acceptance Date: 1/18/2009
Publication Date: 2/7/2009
Citation: Brandenberger, L.P., Webber III, C.L., Shrefler, J.W., Carrier, L.K., Havener, R.L., Adams, R.J. 2009. Racer efficacy study, Fall 2008. In: Brandenberger, L., Wells, L., editors. 2008 Vegetable Trials Report, Oklahoma State University, Division of Agricultural Sciences and Natural Resources, Department of Horticulture & Landscape Architecture. Stillwater, OK. MP-164, p. 67-68.

Interpretive Summary: Racer (ammonium nonanoate) is a non-selective contact that controls several weed species. Racer has been labeled by EPA in the past year for weed control in food crops and is close to receiving approval for use by organic producers. The objective of this study was to verify results from the 2007 study regarding the effectiveness of Racer for control of several weed species. The study was completed at the Oklahoma State University Vegetable Research Station in Bixby, Oklahoma. Plots were arranged in a randomized complete block design with four replications, each plot consisted of an area 10 ft wide by 15 ft long. Treatments were applied on 28 August 2008 using a tractor mounted CO**2 sprayer with 3 nozzles with a 20-inch nozzle spacing for a total spray width of 60 inch. To maintain the same spray pattern for each nozzle type, the nozzle pressure was held constant and tractor speed was adjusted to achieve different overall application rates, i.e., 35 or 70 gallons per acre (GPA). 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, plus a weedy check. Racer proved to be an effective contact herbicide for controlling both weed species in the study. The two higher rates of Racer were more effective than the lower rate, although even the low rate resulted in higher levels of weed control than the untreated check. As in 2007, the overall spray application rate of 70 GPA appears to have diluted the active ingredient enough to reduce its effectiveness. Based upon these results, it is recommended that Racer be applied at 11.2 and 14.4 lb ai/acre for Racer and a spray volume of 35 GPA.

Technical Abstract: Research in 2007 demonstrated the effectiveness of Racer (ammonium nonanoate) for burn-down control of several weed species. Racer has been labeled by EPA in the past year for burn-down weed control in food crops and is close to receiving approval for use by organic producers. The objective of this study was to verify results from the 2007 study regarding the effectiveness of Racer for control of several weed species. The study was completed at the Oklahoma State University Vegetable Research Station in Bixby, Oklahoma. Plots were arranged in a randomized complete block design with four replications, each plot consisted of an area 10 ft wide by 15 ft long. Treatments were applied on 28 August 2008 using a tractor mounted CO**2 sprayer with 3 nozzles with a 20-inch. nozzle spacing for a total spray width of 60 inch. To maintain the same spray pattern for each nozzle type, the nozzle pressure was held constant and tractor speed was adjusted to achieve different overall application rates, i.e., 35 or 70 gallons per acre (GPA). 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, plus a weedy check. Racer proved to be an effective contact herbicide for controlling both weed species in the study. The two higher rates of Racer were more effective than the lower rate, although even the low rate resulted in higher levels of weed control than the untreated check. As in 2007, the overall spray application rate of 70 GPA appears to have diluted the active ingredient enough to reduce its effectiveness. Based upon these results, it is recommended that Racer be applied at 11.2 and 14.4 lb ai/acre for Racer and a spray volume of 35 GPA.