recommended herbicide for control of pricklypear on Texas rangelands. Recently
a generic version of this same herbicide with the trade name Triumph 22K has ...
2007 Comparison of Picloram Options for Pricklypear Control Allan McGinty, Extension Range Specialist, San Angelo Charles Hart, Extension Range Specialist, Stephenville Bob Lyons, Extension Range Specialist, Uvalde Alyson McDonald, Extension Program Specialist, Ft. Stockton Barron Rector, Extension Range Specialist, College Station Rachel Bauer, County Extension Agent, Caldwell Jon Gerbasch, County Extension Agent, Cameron Wade Hibler, County Extension Agent, Burnet Lee Howard, County Extension Agent, Stanton Rafael Realivasquez, County Extension Agent, Presidio Robert Scott, County Extension Agent, Stephenville Whit Weems, County Extension Agent, Hamilton SUMMARY For many years Tordon 22K (picloram), manufactured by Dow AgroSciences, has been the recommended herbicide for control of pricklypear on Texas rangelands. Recently a generic version of this same herbicide with the trade name Triumph 22K has become available for use on Texas rangelands. This project compares the efficacy of Tordon 22K vs. Triumph 22K when used as either an individual plant pad spray (Brush Busters) or as a ground broadcast treatment for control of pricklypear. In support of this project herbicide plots were established in 8 counties across Texas. One year after treatment, both herbicides provided approximately the same apparent mortality, averaging 78% for Tordon 22K and 76% for Triumph 22K. This data should be considered preliminary. Control may change over the next growing season. Final control values will not be available until 2008. OBJECTIVES Pricklypear is a major noxious plant on Texas rangelands. For many years the only herbicide recommended for control of this plant has been Tordon 22K, which contains the active ingredient picloram. Recently a “generic” version of picloram called Triumph 22K has become available in Texas through Albaugh, Inc. Triumph 22K contains the exact same active ingredient (picloram), at the same concentration (2 lbs a.i./gal) as Tordon 22K. The “inerts” in Triumph 22K, those compounds that affect mixing and stability of the herbicide, are unknown and not necessarily the
same as Tordon 22K. The “inerts” can affect performance of a herbicide in the field. The objective of these trials is to compare Tordon 22K to Triumph 22K when applied as an individual plant pad spray or ground broadcast spray for control of pricklypear. MATERIALS AND METHODS Table 1 lists the location, date of application and treatments applied at each site. Each site included a comparison of Tordon 22K to Triumph 22K. The sites in Erath and Hamilton counties also included the herbicides Surmount and Vista in the comparisons. Individual plant treatments (pad sprays) were applied using a 4-wheel ATV or backpack sprayer, equipped with hand wands and X-8 adjustable cone nozzles. Herbicides were mixed with water at a 1% concentration. A non-ionic surfactant was added at a concentration of 1/4%. HiLight Blue Dye was also added to the spray mix at an approximate concentration of 1 oz/3 gal of spray. All pads were sprayed to wet, but not to the point of dripping. The single ground broadcast site in Burnet County was established using a 4-wheel ATV, equipped with a KLC-9 Fieldjet nozzle. Applications were made at 20 psi using a 15 ft swath and a total spray volume of 10 gpa. Plot size was approximately ¼ acre. Tordon 22K and Triumph 22K were applied at a rate of 1 qt/acre. A non-ionic surfactant was added to the water:herbicide mix at a concentration of 0.25%. Table 1. County, ranch, date of application and treatments applied County Milan Erath Hamilton Martin Presidio Caldwell Burnet Irion
Site/Ranch Jon Gersbach Robert Scott Brian Ogle Corky Blocker Hubbard Leavell Duncan D-Cross Hofackey
Date 11-26-06 10-26-06 10-20-06 8-31-06 9-24-06 7-25-06 9-14-06 8-10-06
Treatment Applied IPT IPT IPT IPT IPT IPT Broadcast IPT
RESULTS AND DISCUSSION One year following treatment there was little difference in the apparent mortality of pricklypear regardless of the herbicide used (Table 2). Apparent mortality of Tordon 22K, applied as an individual pad spray (Brush Busters) averaged 78% across 6 locations, and Triumph 22K averaged 76%, not a significant difference. Only two locations included the herbicides Surmount and Vista (additional alternatives for pricklypear control) and they provided similar control to Tordon 22K and Triumph 22K at that same location. Only one location, Burnet County, was treated using a broadcast application. One year after treatment, apparent pricklypear mortality was 80% for Tordon 22K and 60% for Triumph 22K. Pricklypear dies slowly following treatment with herbicide. Often 2 to 3 years is required before maximum control is obtained. This data should be considered preliminary. These herbicide trials will be re-evaluated in 2008.
Table 2. Percent apparent mortality of pricklypear one year after treatment. Burnet county data is result of broadcast application and is not included in the average. County Milam Erath Hamilton Martin Presidio Caldwell Irion Burnet Average
Tordon 22K NE 45 65 100 95 86 75 80 78
One-year Apparent Mortality, % Triumph 22K Surmount NE 40 50 70 80 100 89 85 70 60 76 65
Vista 55 75
65
NE – Not evaluated
ACKNOWLEDGMENTS This project was supported by 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.
