2013 Progress Report

Transcription

1 2013 Progress Report Individual Plant Treatments of Aminocyclopyrachlor on Yaupon Site Locations: Cooperators: Authors: Brazos and Robertson Counties Texas A&M Range Area and Camp Cooley Ranch Dr. Barron Rector, Extension Range Specialist, College Station Edward Schneider, County Extension Agent, Robertson County Will Hatler, DuPont Crop Protection Summary Yaupon chemical control trials were established in 2011 and 2012 to evaluate the efficacy of aminocyclopyrachlor alone and combined with other products when applied as a foliar individual plant treatment. Treatment results will be evaluated at one and two years after treatment. Objective Yaupon (Ilex vomitoria) is a low-growing, evergreen shrub in the Holly family. It will form a trunk when trimmed but usually grows as a woody shrub. A native, cool- and warm-season perennial, this plant has branches that can reach 20 feet tall. Although yaupon provides good browse for wildlife and fair grazing for livestock, populations can become dense enough to be a nuisance to landowners seeking to maintain brush free pastures. Currently, individual plant treatments with tebuthiuron pellets or stem treatments with triclopyr are recommended for yaupon control. The objective of this study is to evaluate the efficacy of aminocyclopyrachlor applied alone and in combination with other products as foliar individual plant treatments on yaupon. Materials and Methods Research trials were established on September 14, 2011 at the Texas A&M University Range Area in Brazos County. Two replications of 9 individual plant treatments were applied to yaupon foliage. Plants in rep 1 consisted of mature yaupon not previously burned by prescription, ranging from 2-8 feet tall with some drought symptoms and leaf browning evident. Plants in rep 2 were regrowth from previously burned yaupon, ranging from 6 inches to 4 feet tall with some drought symptoms and leaf browning evident.

2 Additional trials were established on November 7, 2012 at the Texas A&M Range Area in Brazos County and on November 13, 2012 at the Camp Cooley Ranch in Robertson County. Plants at both sites were healthy with good leaf cover and color. All treatments in this study were applied with a hand-pump backpack sprayer equipped with a ConeJet X-8 nozzle, spraying all foliage to wet but not to the point of runoff. Plot evaluations will be conducted at 1 and 2 years after treatment by determining the number of dead plants in relation to the total number treated to arrive at percent apparent mortality of plants. Environmental conditions on the day of application are listed in Table 1 and specific treatment details are provided in Tables 2 and 3. Table 1. Environmental conditions on the day of application for yaupon IPT trials established in Brazos County in Site Date Spray Time Wind Speed/ Direction Soil Temp. Air Temp. Soil Type/ Moisture RH Brazos Co. 9/14/11 10:00-3: mph/s 94⁰F 85-99⁰F Clay/Low 31-49% Brazos Co. 11/7/12 9:25-12: mph/n 62⁰F 68-77⁰F Clay/Low 35% Robertson Co. 11/13/12 10:30-1: mph/n 60⁰F 56-63⁰F Sandy Loam/Low 35-45% Table 2. Herbicides and rates for yaupon IPT trials established in Brazos County in NIS at 0.5% v/v was added to all treatments. Treatment No. Herbicide IPT Rate Material/plot TSV/plot # Plants Treated Rep 1 1 MAT % v/v ml 2.5 gal MAT % v/v 18.9 ml 2.0 gal % v/v 37.9 ml 2.0 gal MAT % v/v 75.7 ml 2.0 gal % v/v 18.9 ml 2.0 gal. 30 Remedy Ultra 0.25% v/v 18.9 ml 0.50% v/v 37.9 ml 2.0 gal. 30 Remedy Ultra 0.50% v/v 37.9 ml 7 DPX-RDQ oz./gal oz. 2.0 gal DPX-RDQ oz./gal oz. 2.0 gal DPX-RDQ oz./gal oz. 2.0 gal. 69 Rep 2 1 MAT % v/v 4.7 ml 1.0 gal MAT % v/v 9.5 ml 1.0 gal % v/v 18.9 ml 1.0 gal MAT % v/v 37.9 ml 1.0 gal % v/v 9.5 ml 1.0 gal % v/v 18.9 ml 1.0 gal. 61 Remedy Ultra 0.50% v/v 18.9 ml 7 DPX-RDQ oz./gal oz. 1.0 gal DPX-RDQ oz./gal oz. 1.0 gal DPX-RDQ oz./gal oz. 1.0 gal. 60

3 Table3. Herbicides and rates for yaupon IPT trials established in Brazos and Robertson Counties in NIS at 0.5% v/v was added to all treatments. Treatment No. Herbicide IPT Rate Material/plot TSV/plot # Plants Treated Brazos Co. 1 MAT % v/v 37.9 ml 2.0 gal MAT % v/v 75.7 ml 2.0 gal % v/v 37.9 ml 2.0 gal. 102 Roundup PowerMax 0.50% v/v 37.9 ml 4 DPX-RRW % v/v 56.8 ml 1.0 gal DPX-RRW % v/v 75.7 ml 1.0 gal oz./gal. 5.1 g 1.0 gal Surmount 2.00% v/v 75.7 ml 1.0 gal. 65 Robertson Co. 1 MAT % v/v 18.9 ml 1.0 gal MAT % v/v 37.9 ml 1.0 gal % v/v 18.9 ml 1.0 gal. 61 Roundup PowerMax 0.50% v/v 18.9 ml 4 DPX-RRW % v/v 56.8 ml 1.0 gal DPX-RRW % v/v 75.7 ml 1.0 gal oz./gal. 5.1 g 1.0 gal Surmount 2.00% v/v 75.7 ml 1.0 gal Remedy Ultra Diesel 15.00% v/v 85.00% v/v 70.9 ml ml 0.13 gal. 52

4 Results and Discussion Final evaluation of the 2011 trials was conducted on October 8, 2013 (Table 4). At 2 years after treatment, apparent mortality was the highest in plots that had previously been burned. The same treatments on mature, unburned yaupon provided substantially lower apparent mortality. Averaged across both replications, DPX-RDQ98 had the highest apparent mortality (72%). Lower rates of MAT28 alone provided no mortality. Tank mixing Remedy Ultra with MAT28 did not appear to provide any initial advantage over MAT28 alone. Initial evaluation of 2012 trials was conducted on August 12, 2013 (Table 5). Averaged across both sites, MAT28 at 1% v/v and RRW96 at 1.5 and 2.0% v/v performed the best at 1 year after treatment, with initial mortality at or above 89%. Final evaluations will be conducted in Table 4. Herbicides, rates and results for yaupon IPT trials established in Brazos County in NIS at 0.5% v/v was added to all treatments. % Apparent Mortality 2 YAT Treatment No. Herbicide IPT Rate Rep 1 Rep2 AVG 1 MAT % v/v MAT % v/v % v/v MAT % v/v % v/v Remedy Ultra 0.25% v/v 0.50% v/v Remedy Ultra 0.50% v/v 7 DPX-RDQ oz./gal DPX-RDQ oz./gal DPX-RDQ oz./gal Table 5. Herbicides, rates and results for yaupon IPT trials established in Brazos and Robertson Counties in NIS at 0.5% v/v was added to all treatments. % Apparent Mortality 1 YAT Treatment No. Herbicide IPT Rate Brazos Co. Robertson Co. AVG 1 MAT % v/v MAT % v/v % v/v Roundup PowerMax 0.50% v/v 4 DPX-RRW % v/v DPX-RRW % v/v oz./gal Remedy Ultra 0.25% v/v 7 Surmount 2.00% v/v Remedy Ultra Diesel 15.00% v/v 85.00% v/v

5 Acknowledgements This project was supported by DuPont Crop Protection, the Texas A&M Department of Ecosystem Science and Management, Robertson County and cooperating landowners.