Tolerance of WideStrike Cotton to Ignite Tank Mix Applications

Glyphosate-resistant (GR) weeds are a major issue for Tennessee cotton growers and can be problematic to control and prevent yield loss.  GR horseweed, GR giant ragweed, and GR Palmer amaranth are the three GR weeds that can currently be found in Tennessee.  GR Palmer amaranth has become the most difficult to control of these.  As a result, many growers have moved to a Ignite based system to manage GR weeds which includes a pre applied herbicide followed by at least one over-the-top Ignite application.  Liberty Link cotton varieties are planted on just a few acres in Tennessee due to inconsistent performance of those varieties in the state.  Over 60% of the cotton acres in Tennesse are planted to a Widestrike cotton variety which have tolerance to both glyphosate and glufosinate. 

The Widestrike cotton varieties have moderate tolerance to Ignite.  The leaf burn and stunting from an Ignite application on Widestrike cotton ranges from 15 to 25% and rarely to date has this visual injury resulted in yield loss.  However cotton growers often want to tankmix other pesticides in with Ignite and spray over the top of WideStrike cotton.  Will these tankmixes cause more injury to Widestrike cotton?  In addition, cotton that has been stressed by thrips often needs a follow up insecticide most often at the timing when growers should apply Ignite.  Will these tankmixtures injure Widestrike cotton that is already under thrip injury?  Data from two different studies examing these tankmixtures will be discussed.