Residuals help fight resistance

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For years, we’ve waited for the Roundup Ready 2 Xtend trait for soybeans and the herbicide to use over the top. With EPA approval of dicamba-tolerant chemistry late last year, we are finally going to see what this technology brings to the table this growing season.

Stacked with both dicamba and glyphosate herbicide tolerance, the Xtend platform gives growers benefits not only on the genetics side but on the weed control side as well. The technology offers the yield and quality potential of Roundup Ready 2 soybeans with additional tools to control tough weeds such as waterhemp, marestail, giant ragweed, and Palmer amaranth, just to name a few.

Since last season, XtendiMax with VaporGrip and Engenia herbicides have both been labeled for use in Xtend soybeans. These are advanced formulations of dicamba with reduced volatility. New tank-mix products and nozzles have also been approved for use with the Xtend dicamba-tolerant crops.

We will still need to use tank-mix partners such as Authority, Sonic, or Valor. Diversifying your weed control program with different modes of action can preserve the effectiveness of the new seed traits as well as the new herbicide products designed to work with them.

The best strategy for any technology—Xtend, Roundup Ready, Enlist or Liberty Link—is overlapping residuals. This is the use of a full rate of a pre-emerge herbicide applied at planting followed with a post-emerge application of another residual 20 to 30 days later. The second residual should be applied and activated by rain before time expires on the first herbicide activity. The goal is to never let weeds out of the ground.

I believe the greatest benefit of this system will be in the burndown market. You can make a burndown application with dicamba and residual and have no plant-back restrictions. However, this won’t be the glyphosate system you have been accustomed to. This technology will provide a benefit only if you use it right. We have heard about all the risk associated with dicamba. If we make sure we are following the proper guidelines, I believe we can use these products successfully.

During my meeting schedule over the winter, I had the opportunity talk internally to my fellow MFA employees as well as producers about the advantages and challenges of dicamba-tolerant crops. I generally tried to scare folks to the ledge, and then walk them back. I would always end my discussion by saying, “Don’t be scared of it.” We must be diligent and cautious of this system, but I want growers to benefit from the technology without being constantly scared. That’s when we tend to make mistakes. Unfortunately, with dicamba, we’ve learned mistakes can be costly. Compared to glyphosate, it takes such a small amount of dicamba to show damage in an off-target crop. The sensitivity to non-tolerant plants is unlike anything we’ve dealt with before.

No matter what weed control program you are using on your farm, I hope it is successful. But don’t forget where we’ve come from. Weed resistance has been here for a long time, and it’s not going away any time soon.

If you have questions or would like to develop sound weed control options, see your local MFA Agri Services or AGChoice location.


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