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Title: Racer efficacy study

Author
item BRANDENBERGER, LYNN - Oklahoma State University
item Webber Iii, Charles
item SHREFLER, JAMES - Oklahoma State Experiment Station
item CARRIER, LYNDA - Oklahoma State University
item HAVENER, ROBERT - Oklahoma State University
item ADAMS, ROBERT - Oklahoma State University

Submitted to: Extension Publications
Publication Type: Experiment Station
Publication Acceptance Date: 4/15/2009
Publication Date: 5/5/2009
Citation: Brandenberger, L.P., Webber III, C.L., Shrefler, J.W., Carrier, L.K., Havener, R.L., Adams, R.J. 2009. Racer efficacy study. In: Brandenberger, L., Wells, L., editors. 2008 Vegetable Weed Control Studies. Oklahoma State University, Division of Agricultural Sciences and Natural Resources, Department of Horticulture & Landscape Architecture. Stillwater, OK. MP-162. p. 31-32.

Interpretive Summary: 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 August 28, 2008 using a tractor mounted CO2 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 application rates of 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 the weed species in this 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: Racer (ammonium nonanoate) is a non-selective contact herbicide 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 August 28, 2008 using a tractor mounted CO2 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, nozzle pressure was held constant and tractor speed was adjusted to achieve application rates of 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 the weed species in this 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.