Last week I participated in an educational event in the Kingsville area that focused on managing mesquite on our rangelands.  A new herbicide, Sendero by Dow AgroSciences, was discussed in great detail.  This product has two active ingredients, aminopyralid + clopyralid, which means that it is not a restricted use herbicide and does not require a pesticide applicator’s license to purchase. 

Recent testing of this herbicide has shown that it provides nearly 40 percent more consistent control than the traditional mix of Remedy Ultra and Reclaim.

So when is the best time to make foliar applications of herbicide to mesquite?  Research has shown that the optimum time to treat is when:

1) The soil temperature at 12 inches below the surface is 75   degrees or higher;

2) the mesquite leaves are a dark green color all over, rather than some light green new growth at the ends.  Applications should be avoided immediately following a significant rainfall, as the production of too much new growth will reduce the movement of herbicide to roots.  This could be a problem with recent rains.  Wait until all the leaves have turned a dark green color again before treating.

3) The mesquite tree is not flowering or elongating the beans.  In the Coastal Bend this year that should be occurring around 63 to 72 days after bud break or from May 4 to May 12, assuming a March 1 bud break date.  So the optimum time to make a foliar herbicide application this year, if all of the environmental conditions are good, would be approximately from May 13 to May 30.

4) The leaves are healthy. No more than 25 percent of the leaves can have damage by insects, hail, disease, or rodents. 

Soil moisture is another important factor to consider before treating.  Even though mesquite is a deep rooted plant, treatments should be delayed if plants are under drought stress.

If you miss the foliar treatment timing window, you have other options to help manage mesquite, including mechanical treatments or basal stem treatments.  More information regarding honey mesquite control may be obtained from your local County Extension Office or at the web site: http://pestman.tamu.edu/