Efficacy of Amincocyclopyrachlor for Annual Broomweed Control

Transcription

1 SUMMARY Efficacy of Amincocyclopyrachlor for Annual Broomweed Control Charles R. Hart, Extension Range Specialist, Stephenville Will Hatler, Extension Program Specialist, Stephenville Todd Vineyard, County Extension Agent, Erath County 2009 Research plots were established in 2008 and 2009 to determine the efficacy of aminocyclopyrachlor for annual broomweed control at various rates. Results will be evaluated incrementally up to one year after treatment. OBJECTIVES Broomweed is a warm-season native plant in the Sunflower family. It occurs in both annual and perennial varieties, with the perennials distinguishable by their un-branched, erect stems. Both varieties are of poor forage value and perennial broomweed is poisonous to livestock, causing abortions when consumed during late pregnancy. It can cause death if consumed as more than 20 percent of the diet. The habitat is broad, ranging from dry native ranges to disturbed sites. Extreme infestations reduce forage production but may not indicate overgrazed ranges because broomweed populations fluctuate naturally. This project was established to investigate the efficacy of DuPont s new aminocyclopyrachlor chemistry for annual broomweed control. MATERIALS AND METHODS Test sites were established in Erath County on May 28, Ten treatments were applied on broomweed plots in a field that is intermittently plowed and planted. Numbered compounds MAT28 and KJM44 (forms of aminocyclopyrachlor) were applied at varying rates. In addition, Escort and Telar were paired with MAT28 in 2 of the treatments, and one treatment was a combination of Escort and Range Star. All treatments included a non-ionic surfactant at the rate of 0.25 volume/volume, with the exception of treatment 4 where methylated-seed oil was added at 1 volume/volume (Table 1). All 2008 plots were sprayed with ground broadcast spray equipment. A boom sprayer equipped with flat fan nozzles delivering 20 gallons per acre total spray volume and a 4 foot swath width was used. All plots measured 0 ft² and were replicated. Additional plots were established on May 18, 2009 at the same site in Erath County. Two separate protocols testing varying rates of MAT28 were applied. All treatments included a nonionic surfactant at the rate of 0.25 volume/volume and had a total spray volume of 20 gallons

2 per acre. A hand boom sprayer equipped with TT11003 flat fan nozzles spraying a 10 foot swath width was used to spray all plots, which were replicated and measured 0 ft² each. Visual evaluations will be completed at 15,, 60, 90 and 360 days after all treatments to determine treatment efficacy. Herbicides and rates for all treatments are presented in Table 1. Table 1. Herbicides and rates for annual broomweed treatments applied in 2008 and 2009 in Erath Co. Plot No. Herbicide Rate (a.i./acre) 2008 Treatments 1 MAT28 + NIS 0.25 oz v/v 2 MAT28 + NIS 0.50 oz v/v 3 MAT28 + NIS 1.00 oz v/v 4 MAT28 + MSO 1.00 oz v/v 5 KJM44 + NIS 1.00 oz v/v 6 MAT28 + NIS 1.50 oz v/v 7 MAT28 + NIS 2.00 oz v/v 8 Escort + Range Star + NIS 0.15 oz lb v/v 9 MAT28 + Escort + NIS 1.00 oz oz v/v 10 MAT28 + Telar + NIS 1.00 oz oz v/v 11 Control 2009 Protocol 1 NIS at 0.25 v/v was added to all treatments 1 MAT oz 2 MAT oz 3 MAT28 + Telar 0.94 oz oz 4 MAT28 + Telar 1.88 oz oz 5 MAT28 + Telar 2.82 oz oz 6 MAT28 + Matrix 0.75 oz oz 7 MAT28 + Matrix 1.13 oz oz 8 MAT28 + Matrix 1.50 oz oz 9 Aminopyralid + Escort 1.75 oz oz 10 Aminopyralid 1.75 oz 11 Grazon P+D oz. product/acre 12 MAT28 + Escort 0.94 oz + 0. oz 13 MAT28 + Escort 1.88 oz oz 14 Control 2009 Protocol 2 NIS at 0.25 v/v was added to all treatments 1 MAT oz 2 MAT oz 3 MAT oz 4 MAT oz 5 DPX-T Range Star 0.15 oz oz. product/acre 6 Grazon P+D oz. product/acre 7 MAT28 + DPX-T oz oz 8 MAT28 + 2,4-D 1.00 oz oz 9 Control

3 RESULTS AND DISCUSSION Result evaluations completed at 15,, 60, 90 and 360 days after treatment are presented in Table 1. All 2008 plots showed browning at 15 and progressively higher treatment effects at each following evaluation. After 90 days, the best results were observed in Plot 7 with MAT28 at 2.00 oz./acre showing 87 mortality, and Plot 9 which combined MAT28 with Escort showing 88 mortality. There did not appear to be an advantage gained by using methylatedseed oil rather than non-ionic surfactant. As would be expected for weed control, treatment effect at 360 was less than at 90 for all 2008 plots. However, the KJM44 at 1.00 oz. and MAT28 at 1.50 oz. both showed regrowth reduction above 70 (Figure 1). All treatments applied in 2009 showed browning at 15 which became significantly more notable at. At 60 days at least 90 of plants in all treatments were brown and this trend continued through the mortality evaluation at 90 days (Figures 2 & 3). It should be noted that the site received no rainfall between the 15 and 90 day evaluation which caused browning of broomweed outside the plots. This was evidenced by the plant browning and mortality noted in the control plots at 60 and 90. Final evaluations will be made at 1 year after treatment in Table 2. Results at 15,, 60, 90 and 360 days after treatments on annual broomweed applied in Erath County in 2008 and Percent mortality is averaged across 3 replicated plots. Treatment Rate (a.i./ac) Treatments NIS was added at 0.25 v/v to all but treatment 4. MAT oz ± ± 25.3 MAT oz ± ± 45.8 MAT oz ± ± 36.8 MAT28 + MSO 1.00 oz ± ± v/v KJM oz ± ± 13.5 MAT oz ± ± 9.6 MAT oz ± ±.8 Escort + Range Star 0.15 oz ± ± lb + MAT28 + Escort 1.00 oz ± ± oz. MAT28 + Telar 1.00 oz ± ± oz. Control ± ± Protocol 1 NIS at 0.25 v/v was added to all treatments. MAT oz ± 0.0 MAT oz ± 0.0 MAT28 + Telar 0.94 oz ± oz MAT28 + Telar 1.88 oz oz ± 0.0

4 Table 2. Results at 15,, 60, 90 and 360 days after treatments on annual broomweed applied in Erath County in 2008 and Percent mortality is averaged across 3 replicated plots. Treatment Rate (a.i./ac) MAT28 + Telar 2.82 oz ± oz MAT28 + Matrix 0.75 oz ± oz MAT28 + Matrix 1.13 oz ± oz MAT28 + Matrix 1.50 oz ± oz Aminopyralid + Escort 1.75 oz ± oz Aminopyralid 1.75 oz ± 0.0 Grazon P+D oz ± 0.1 product/acre MAT28 + Escort 0.94 oz ± oz MAT28 + Escort 1.88 oz ± oz Control ± Protocol 2 NIS at 0.25 v/v was added to all treatments. MAT oz ± 0.1 MAT oz ± 0.0 MAT oz ± 0.0 MAT oz ± 0.0 DPX-T Range Star 0.15 oz ± oz. product/acre Grazon P+D oz ± 0.0 product/acre MAT28 + DPX-T oz ± oz MAT28 + 2,4-D 1.00 oz ± oz Control ±

5 Percent Mortality of 2008 Broomweed Plots 90 & 360 Days After Treatment Treatment No Figure 1. Percent mortality of 2008 broomweed treatments at 90 and 360 days after treatment, averaged across 3 replications. Error bars indicate standard deviation. Percent Mortality of 2009 Broomweed Protocol 1 90 Days After Treatment Treatment No. Figure 2. Percent mortality of 2009 broomweed protocol 1 at 90 days after treatment, averaged across 3 replications.

6 Percent Mortality of 2009 Broomweed Protocol 2 90 Days After Treatment Treatment No. Figure 3. Percent mortality of 2009 broomweed protocol 2 at 90 days after treatment, averaged across 3 replications. ACKNOWLEDGMENTS This project was supported by DuPont Crop Protection and cooperating counties and landowners. The information given herein is for educational purposes only. Reference to commercial products or trade names is made with the understanding that no discrimination is intended and no endorsement by AgriLIFE Extension is implied.