Since the launch of Roundup Ready Xtend soybeans we have observed great success in terms of weed control. The use of approved dicamba formulations in soybeans adds another great tool in the weed management tool belt to manage tough-to-control weeds such as waterhemp and marestail. While the federal label has changed from the 2022 growing season for some states, be sure to double check that state specific labels haven’t changed. The link to a previous article discusses the new label changes can be found here. To steward this technology, it’s imperative that applications are optimized to their fullest potential so maximum weed control is possible. The following best management practices below have proved to be beneficial across the Midwest when applying Engenia®, Tavium® and Xtendimax® in Xtend® or XtendFlex® soybeans.
Nozzles and Carrier Volume: Nozzle selection can be an emotional and daunting task. Factors that go into selecting the correct nozzle are: 1) droplet spectrum, 2) desired application speed, 3) pressure and gallons per acre, 4) sprayer system (Pulse Width Modulation versus standard) and lastly 5) approval lists. Approved nozzles provide ultra-course droplets to help mitigate particle drift. Ultra-coarse size droplets lessen overall coverage. Consequently, increasing the carrier volume may result in greater efficacy of tough-to-control weeds and volunteer corn. Reduced control of volunteer corn in the past was likely due to poor coverage in scenarios where clumps of plants existed. Increasing the carrier volume will result in more droplets to cover those clumps, reducing the chance for escapes.
Adjuvants: Adjuvants are in integral part of any postemergence herbicide application. Without the proper adjuvant, control is often reduced. With the application of any approved dicamba formulation an approved drift reduction adjuvant (DRA) and volatility reduction adjuvant (VRA) are mandatory. Do not forget about water conditioning adjuvants. Most of the water used for applications contains hard water cations including calcium, magnesium and iron, which tie up weak acid herbicides such as dicamba, rendering the herbicide less effective. Approved, water conditioning adjuvants free of ammonium sulfate should be added to the tank to mitigate hard water tie up of the herbicide. Oil adjuvants are necessary with certain tank mix partners, but make sure that they are approved for use prior to mixing.