Experiences with the Roundup Ready Xtend Crop System in Oklahoma

Horseweed and pigweed are the most difficult to control weeds in Oklahoma cotton production.  Glyphosate resistant populations of both weeds are prevalent across most if not all of our cotton producing areas.  The difficulty experienced with these two problem weeds have caused producer’s to reconsider both their weed control strategies as a whole and even their production style (no-till or conventional tillage).  Due to their competitive nature, when left uncontrolled their impacts not only reduce yields but often render the crop un-harvestable.  Dicamba has been a standard component for effective horseweed control programs in Oklahoma for many years.  In addition, dicamba’s effectiveness on pigweed has also been proven in other crops.  The ability to effectively control these weeds with the new formulation of dicamba in the Roundup Xtend Cropping System will be extremely valuable to Oklahoma producers.  Weed control trials were established in Oklahoma to evaluate the effectiveness of this system on troublesome weeds and to help provide a baisis for developing recommendations once this trait is available in commercial seed lines.  In addition we evaluated the effectiveness of these systems when utilizing recommended spray application requirements (nozzle type, droplet size, etc.) presumed to be required with the release of this herbicide trait.  Both in-crop and non-crop studies were established to evaluate the safety and effectiveness of this system.