Here we are approaching June 1, and soybeans are emerging all around the Wheat Growers region. With the emergence of soybeans there also has come discussion about dicamba application in dicamba tolerant soybeans.
Dicamba tolerant soybeans are a unique new weed management tool. And as with any new management tool, it takes time to learn the most effective uses of that tool. And right now, we are learning what it takes to effectively apply herbicides in this new soybean system.

Here at Wheat Growers we offer both XtendiMax and Engenia (dicamba) herbicides for growers for dicamba tolerant soybeans. These two, along with an offering from Dupont Pioneer, are the only dicamba products legally approved for application in dicamba tolerant soybeans after planting.

Based on the feedback we’re receiving from our agronomists and members, we are gaining valuable insights and starting to develop some best practices that we can pass along.

To effectively and legally apply these approved dicamba products, growers must first and foremost follow all the legal requirements for setting up sprayers and nozzles; checking tank mixes and required additives on the respective application websites; obtaining, reading and following the required labels and having them on hand when applying. Respective labels and application requirements can be found at for Engenia Herbicide and for XtendiMax Herbicide. Reading and following all label requirements and restrictions is the applicator’s responsibility.

The Supplemental Labels for application in dicamba tolerant crops for each herbicide will list a series of application requirements, which also must be followed. In addition, field experience this spring and detailed conversations with Technical Service representatives from both BASF and Monsanto, have led me to develop a set of best management practices. Here is my best guidance for getting these applications to be the most efficacious they can be:

1.  Spray with 15+ GPA (gallons per acre) carrier. Coverage is critical, and 15 GPA simply is 50% more drops versus the label minimum of 10 GPA. Spraying at the label minimum does not assure adequate coverage and the application will not be effective if we do not have enough droplets applied.
2.  Add an oil into the mix, especially if not planning to add a non-AMS water conditioner. Depending on the dicamba label, certain oils can be added without a specialized Drift Reduction Agent (DRA) in the mix. This is critical. In recognized weed control guides like the NDSU Weed Management Guide, Dicamba is almost always recommended with an oil added to the mix.
3.  Keep mixes as simple as possible. We know dicamba plus Roundup plus simple additives killed weeds well. Let's keep that in mind as we create mixes.
4.  If a Drift Reduction Agent (DRA) is required in the spray mix (see websites), effective management includes three steps:

a. Keep the rate as LOW as possible. DRA’s are effectively “thickeners.” You do not want excess product in the tank as it significantly affects droplet size and distribution.
b. Keep to the UPPER END of the carrier volume (15+ GPA). This will assure an adequate number of droplets being applied to get coverage.
c. Keep to the UPPER END of the approved pressure range for your nozzle. This will assure adequate "singulation" of the droplets and eliminate sheeting as much as possible.

5.  Consider a non-AMS water conditioner, especially if we know we are using hard water. This is not as critical as inclusion of the oil, but will likely help Roundup performance, and I suspect it will help dicamba performance as well. Some oils, like Zaar, have some water conditioning benefits built in.
6.  Be sure to follow recommended spray mixing orders and be sure to allow time for THOROUGH agitation of the spray mixture, especially after a DRA is added to the tank.

Finally, please visit with your local Wheat Growers Agronomist to set up an effective weed management strategy for your crops, and to get the latest recommendations on best management practices for the dicamba-tolerant soybeans system.