Take a good look at this field of corn. You applied residual herbicides early, but you planned on making a postemergence application. Which herbicides should you include in the spray tank?

Answering that question means scouting the field and finding what weeds are present, Bill Johnson says. He’s a Purdue University Extension weed control specialist. It’s also important to know what traits are present in the hybrids you planted. Glyphosate might be an option if corn is glyphosate-tolerant and the weeds you find aren’t likely glyphosate-resistant. Liberty could be an option if the hybrid has the Liberty trait. While 2,4-D is always an option in corn, it may be higher on your possible list if it’s Enlist corn.

“One option here is to think about atrazine, too,” Johnson says. “If you haven’t already applied as much atrazine as the label allows, it can have post activity, but it also has residual activity.

“I would want a residual in the tank to extend the amount of time I have a residual herbicide working in this field. With some of the weeds which can continue germinating later in the season, including waterhemp, it’s important to extend residual activity as long as possible.”

If atrazine isn’t an option for the post tankmix, there are other residual herbicides you can consider, Johnson says. His goal as part of the postemergence trip would be getting another residual herbicide on the soil surface to prevent possible later germination of weeds.