To proactively manage waterhemp in all types of field corn apply Balance Flexx (ND only), Callisto, Camix, Harness/Surpass (acetochlor), Lumax, Prequel (ND only), SureStart/TripleFlex or Verdict pre-emergence. Mixtures of Balance Flexx, Callisto or Prequel with acetochlor will improve waterhemp control. Following the pre-emergence applications, apply glyphosate to Roundup Ready corn and Ignite 280 to LibertyLink corn at maximum single-application rates. In corn lacking herbicide resistance traits consider conventional herbicides such as Callisto, Callisto Xtra, Clarity (at maximum rates and/or in mixtures with other products), Impact, Laudis, Realm Q or Status applied to 1-3-in. waterhemp. To reactively manage glyphosate-resistant waterhemp in corn lacking herbicide resistance traits follow the pre-emergence and conventional postemergence management strategies outlined above. To reactively manage glyphosate-resistant waterhemp in Roundup Ready corn, apply a pre-emergence herbicide and mix one of the conventional postemergence herbicides mentioned above with glyphosate at 1.125 lb. acid equivalent (ae)/acre or apply Halex GT. To reactively manage glyphosate-resistant waterhemp in LibertyLink corn, apply a pre-emergence herbicide and follow with Ignite 280. Mixing atrazine at 0.38 lb. active ingredient (ai)/acre with Callisto, Halex GT, Ignite 280, Impact or Laudis should improve waterhemp control.

Follow label directions for herbicide rates according to soil type and weed size, use of products by geography and crop rotation. Consult the publication PRE and POST Herbicide Diversification Options for information regarding crop rotation and herbicide effectiveness. Scout fields following the first postemergence application to determine need for a second application. If planting no-tillage corn or soybean, apply the necessary preplant herbicides to control emerged waterhemp and other weeds prior to planting and use the appropriate adjuvant(s) and rate(s) for all products in the preplant treatment. In areas of low rainfall, incorporation of preemergence herbicides may improve waterhemp control but may increase crop-injury for some products.

Proper proactive and reactive management of waterhemp this growing season and into the future is necessary to reduce selection of herbicide resistant biotypes and maintain the effectiveness of Roundup Ready crops in the rotation. This is especially true for Roundup Ready sugarbeet in which few herbicides are available to effectively manage waterhemp.