2013 Progress Report. Aerial Application of Dow AgroSciences Products on Mesquite

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1 2013 Progress Report Aerial Application of Dow AgroSciences Products on Mesquite Site Locations: Cooperators: Authors: Callahan, Throckmorton and McClennan Counties Williams, Shaw, Slaughter, Finley and Richards Ranches, McGregor AgriLife Research Station Will Hatler, Extension Program Specialist, Stephenville Byron Gray, County Extension Agent, Throckmorton County Jerry Warren, County Extension Agent, Callahan County Shane McClellan, County Extension Agent, McClennan County Summary Experimental plots were installed over a number of years to test combinations of Dow AgroSciences products applied to mesquite as an aerial broadcast treatment. Trials were established in in Callahan, Throckmorton, and McLennan Counties. Final results have been determined for trials established in and initial evaluations have been completed on trials established in Results indicate that Sendero, a new herbicide that combines aminopyralid and clopyralid, provides consistently higher mesquite mortality than the industry standard treatment of plus. Objective Mesquite is the most common noxious plant invading Texas Rangelands. Mesquite densities can reach such proportions as to severely limit desirable forage growth by competing for nutrients, water, and sunlight. In addition, large quantities of mesquite bean consumption over a period of time (several months) can be toxic to grazing animals. Small quantities of bean consumption can however be considered as a valuable forage. For years, the industry standard in aerial chemical control treatment for mesquite has been + at 0.25 lb lb. active ingredient per acre. Sendero (active ingredient aminopyralid + clopyralid) a relatively new product developed by Dow Agro Sciences that, when tank mixed with other products, has the potential to improve the efficacy of mesquite foliar treatments. The objective of this study is to test Sendero in combination with other products as an aerial broadcast application on mesquite.

2 Materials and Methods Plots were established at the Finley Ranch in Callahan County and the Richards Ranch in Throckmorton County in 2011 (Figures 8-9). A protocol of 7 treatments with combinations of Milestone,, and was applied at both sites. All treatments were applied by Provine Helicopters via helicopter equipped with CP nozzles delivering a total spray volume of 5 gallons per acre with a 48 foot swath width. All plots measured 10 acres in size with mature mesquite trees having few flowers and no beans. A large scale Sendero demonstration plot was established in June 2012 at the McGregor AgriLife Research Station in McClennan County. Eighteen acres of mature mesquite were treated aerially by a helicopter equipped with CP nozzles delivering a total spray volume of 7.5 gallons per acre with a 48 foot swath width. Plants were in good condition with full, dark green leaf growth and no beans present. Evaluation of all trials will be done by executing replicated 100-plant transects in each plot, counting live and dead plants to arrive at average percent apparent plant mortality. Environmental conditions on the day of application are detailed in Table 1 and herbicides, rates and application data are presented in Table 2. Table 1. Environmental conditions on the day of application for mesquite aerial broadcast applications established in Site Date Spray Time Wind Speed/ Direction Soil Temp. Air Temp. Soil Type/ Moisture RH Finley 6/30/11 6:18-7:30 am 0-5 mph/s 89⁰F 78-79⁰F Clay Loam/Low 58-60% Richards 7/1/11 6:00-7:00 am 0-3 mph/s 92⁰F 76⁰F Clay Loam/Low 52-60% McGregor 6/13/12 9:00-9:30 am 1-3 mph/s 89⁰F 80⁰F Loam/Mod. 63% Table 2. Herbicides, rate, and material per plot for mesquite aerial broadcast applications established in Treatment No. Herbicide TSV/acre Rate a.i./acre Rate product/acre Material/plot 2011 Finley and Richards MSO at 1% v/v was added to all treatments* 1 Sendero 9.81 oz oz oz. 2 Sendero 10 gal oz oz oz. 3 Milestone 1.76 oz. 7.0 oz oz oz oz. 4 Sendero 9.81 oz oz oz. 8.0 oz oz. 5 Sendero 9.81 oz oz oz oz oz oz oz. 4 gal oz oz oz oz. 4 gal oz oz McGregor MSO at 1% v/v was added 1 Sendero oz oz oz. *MSO at 0.5% v/v was added to Plot 2 at the 2011 Finley site.

3 Figure 8. Plot layout for mesquite aerial broadcast applications established on the Finley Ranch in Callahan County in 2011.

4 Figure 9. Plot layout for mesquite aerial broadcast applications established on the Richards Ranch in Throckmorton County in Figure 10. Plot layout for Sendero mesquite aerial broadcast demonstration established on the McGregor AgriLife Research Station in McClennan County in 2012.

5 Results and Discussion Final results for trials established in 2011 are presented in Table 6. Final average mortality in plots treated with Sendero ranged from 54-73%, with the higher total spray volume (10 gpa) providing slightly better results. The tank mix of Milestone + had comparable initial apparent mortality at 54%. The combination of Sendero at 9.81 oz. and Remedy Ultra at 8.0 oz. a.i./acre had the highest average mortality rate after 2 years. This was followed closely by the Sendero at a rate of 9.81 oz. a.i/acre mixed with the at 4 oz. a.i./acre that had an average mortality rate of 68.5% mortality. The industry standard + at oz. a.i./acre had the lowest average apparent mortality at 39.5%. That was followed by a treatment of at a.i./acre and reclaim at 4.00oz. a.i./acre had 50% mortality between both sites. It should be noted that severe drought conditions in 2011 may have negatively affected treatment results. Results of the McLennan County site at the McGregor AgriLife Station were not available at the time the report was written. Table 6. Herbicides, rate, and percent mortality 2 years after treatment for mesquite aerial broadcast applications established in MSO at 1.0% v/v was added to all treatments. % Apparent Mortality 2 YAT Treatment No. Herbicide Rate a.i./acre Finley Richards AVG 1 Sendero (5 gpa) 9.81 oz Sendero (10 gpa) 9.81 oz Milestone 1.76 oz Sendero 9.81 oz Sendero 9.81 oz Conclusions Results of this study have shown that Sendero, when tank mixed with Remedy, has significant activity on mesquite. Sendero (Milestone + at 1.76 oz. + a.i./acre) provides consistently higher apparent mesquite mortality than the industry standard treatment of + at 4.0 oz oz. a.i./acre. This study is ongoing and additional results will be reported as they become available. Acknowledgements This project was supported by Dow AgroSciences, Callahan and Throckmorton Counties and the cooperating landowners. Trade names of commercial products used in this report is included only for better understanding and clarity. Reference to commercial products or trade names is made with the understanding that no discrimination is intended and no endorsement by Texas AgriLife Extension Service and the Texas A&M University System is implied. Readers should realize that results from one experiment do not represent conclusive evidence that the same response would occur where conditions vary.