No. 5 Article 3/May 6, 2011

Replanting Corn: How to Control Plants from the Initial Planting

In certain areas of western Illinois, it appears likely that some corn replanting will be needed when field conditions improve. Losses of the initial stand will range from complete to partial, and farmers may need to implement practices to control any remaining corn plants before replanting.

Glyphosate is very effective for controlling existing stands of (sensitive) corn. No waiting interval is specified on the label before replanting, but overall control may be improved if at least 24 hours elapses. Of course, alternative herbicides would be required for any existing stands of glyphosate-resistant corn (or any glyphosate-resistant weeds that might have already emerged).

Paraquat and glufosinate are additional options for control of existing (sensitive) corn stands, although previous research with these herbicides has demonstrated that complete control is not always achieved. Performance is often enhanced when the product is applied in combination with atrazine or metribuzin.

SelectMax has a supplemental label to control an existing stand of glyphosate-resistant corn before replanting field corn. Apply 6 fluid ounces per acre for control of glyphosate-resistant field corn up to 12 inches tall. Applications should include NIS and AMS (do not use a COC or MSO in this particular use), and take care to avoid in-field overlaps or excessive injury to the replanted corn may occur. Do not replant fields treated in this way sooner than six days after application.

Poast, Poast Plus, Fusion, Fusilade, Select, and Assure II are effective for controlling volunteer corn (including volunteer glyphosate-resistant corn) in soybean, but each product label includes an interval that must elapse between application and rotation to or replanting with grass crops such as corn. These intervals range in days from 30 (Poast, Poast Plus, Select) to 60 (Fusion, Fusilade) to as many as 120 (Assure II), making these products unlikely choices for this particular use.--Aaron Hager

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