Pricklypear cactus (Opuntia spp.) is a common invading species on central, south and west Texas rangelands that limits forage production and decreases grazeable acres. Traditionally pricklypear has been controlled by applications of picloram (Tordon 22K) or picloram plus fluroxypyr (Surmount). In the fall of 2013 research was started to analyze the effects of aminopyralid when mixed with Tordon 22K or Surmount. The objectives were to evaluate the speed of desiccation with the addition of aminopyralid and if equivalent mortality could be achieved with lower rates of Tordon or Surmount herbicides when combined with aminopyralid. Trials were conducted in 2013 and 2014 using various tank mix combinations of picloram, fluroxypyr and aminopyralid on pricklypear applied by individual plant treatment, ground broadcast and aerial applications. Based on results obtained from 2013 and 2014 trials, a proprietary formulation (GF-2969, Dow AgroSciences) containing a mixture of aminopyralid, picloram and fluroxypyr was tested.� Trials were established in 2015 and 2016 to test the speed and efficacy of pricklypear control with GF-2969.� Treatments were applied by Individual plant treatment, ground broadcast, and aerial application methods. All trials were evaluated for percent desiccation at 4, 8, 12 and 24 months after treatment.� Results for the tank mix trials in 2013 and 2014 trials indicate that the addition of aminopyralid with Tordon 22K and Surmount resulted in reduced usage rates while maintaining a high rate of efficacy. Results of the 2015 and 2016 trials indicate that a higher level of efficacy is achieved with lower use rates of GF-2969 as compared to Surmount.� GF-2969 also outperformed Tordon 22K at equivalent rates with both greater efficacy and speed.
Oral presentation and poster titles, abstracts, and authors from the Society for Range Management (SRM) Annual Meetings and Tradeshows, from 2013 forward.