Hill Country Agriculture Briefs

Dow AgroSciences has just launched the new herbicide Sendero^TM as the “new standard for mesquite control in Texas.”  So where did this come from?  Texas AgriLife Extension Range Specialists have been working with Dow AgroSciences since 2007 on a joint project to develop a new herbicide mix for mesquite control.  The study looked at varying rates and mixes of three herbicides: clopyralid, triclopyr and aminopyralid.  Fourteen different herbicide treatments were evaluated with a total of 164 aerial plots, each 10 acres in size, over the period of 2007-2011 as part of this study.  All treatments were made in June-July at 4-5 gpa total spray volume and applied by either helicopter or airplane.

In 2009, the mixture of aminopyralid + clopyralid at a 1:4.6 ratio (now called Sendero^TM ) was first evaluated and has proven to be effective at controlling mesquite in annual trials conducted through 2011.  Across three years and 14 sites, percent apparent mortality of mesquite average 66±17.2% one year after treatment on plots treated with 0.61 lb/ac Sendero^TM compared to 57±23.0% on plots treated with the current standard of 0.25 lb/ac Reclaim^TM + 0.25 lb/ac Remedy Ultra^TM.  After two years post-treatment, Sendero^TM plots average 77±10.6% apparent mortality compared to 60±17.8% for Reclaim^TM + Remedy Ultra^TM on all but 2011 treated plots (yet to be evaluated two years after treatment).  The new mixture showed higher average mortality and more consistent control across sites.

This new herbicide has several advantages including 1) A “one jug” pre-mix herbicide for mesquite, no tank mixing of herbicides required, 2) Lower volatility with no ester formulation in the mix, both products are amine formulations, 3) The product is non-restricted use meaning you do not need a pesticide license to purchase or apply, 4) There are no livestock grazing restrictions associated with the product and 5) It appears to be very specific to mesquite, leaving desirable shrubs unharmed.

A recommended use rate of 28 oz. Sendero^TM per acre has been approved through the Herbicide Use Committee as an official recommendation from Texas AgriLife Extension and Texas AgriLife Experiment Station.  It comes with a High (56-75%) control rating and is approved for use in the NRCS EQIP brush control program.  Timing for mesquite control has not changed with this new herbicide and everything that applies to the old standard of Relaim^TM + Remedy Ultra^TM also applies to Sendero^TM .  Two important points are that ONLY a broadcast application rate has been approved at this time as we are still working on rates for Individual Plant Foliar Treatment.  Also, Sendero^TM herbicide will NOT be used as a Basal Bark or Stem application as the product will not mix with diesel or basal bark oils.

Article written by Dr. Charles Hart, Associate Department Head and Extension Program Leader for Ecosystem Science and Management, Texas AgriLife Extension Service