Kochia control in corn and grain sorghum
* An HPPD herbicide. Examples of HPPD herbicides include Lexar EZ or Lumax EZ (premixes of Callisto, Dual II Magnum, and atrazine), Corvus (a premix of Balance Flexx and thiencarbazone methyl), and Balance Flexx. Corvus and Balance Flexx should be mixed with atrazine.
* Verdict, which is a Kixor-powered combination of Sharpen and Outlook herbicides, has activity; however, the residual may be a little too short. Verdict should be mixed with atrazine.
Balance Flexx, and Corvus cannot be applied on coarse-textured soils with shallow (25 feet or less) groundwater. Always consult the labels for details.
If kochia becomes a problem after the corn has emerged, there are several postemergence herbicide options. In Roundup Ready corn, glyphosate should be used even though resistant populations of kochia may be present. It is also a good idea to add one or more herbicides with a different mode of action to the glyphosate. This will not only help control any glyphosate-resistant populations present, but will also help prevent the development of glyphosate-resistant populations of kochia where such populations do not yet exist.
Possible glyphosate tankmix partners would include Status, Impact/Armezon, Callisto, Laudis, Starane, Starane NXT, or Starane Ultra. If an HPPD-containing herbicide was used in the preemergence application (Lexar, Lumax, Corvus, or Balance Flexx), it would be a good idea not to use this mode of action in the postemergence treatment to help reduce the chances of HPPD-resistant weeds developing. Another option in Roundup Ready corn is Halex GT plus atrazine. Halex GT is a premix consisting of a high rate of glyphosate, Dual II Magnum, and Callisto. Atrazine should be added to this product to get the best season-long control of kochia. With Impact, Callisto, Capreno, and Laudis, producers should include a half-pound of atrazine.
In conventional corn, any of those postemergence herbicides mentioned above as tankmix partners with glyphosate can also be used alone, without the glyphosate tankmix partner. Halex GT cannot be used on conventional corn since it contains glyphosate.
Liberty can also be used as a postemergence treatment if the corn is Liberty Link. Liberty alone will not control kochia, however. For kochia control, Liberty should be tankmixed with Status or other more effective postemergence products.
It should be noted that Balance Flexx and Corvus can be applied either preemergence or postemergence up through the 2-leaf stage of corn. If applied postemergence to corn, Balance Flexx and Corvus must be applied with atrazine only. No glyphosate or other adjuvants can be used. These products can do an excellent job of controlling kochia throughout the season if they are tankmixed with at least 1 lb/acre of atrazine. These products require moisture for soil activation, however they do have foliar activity.