Map a season-long weed control strategy

Weeds peeking above five-leaf corn or broadleaves smothering soybeans are scary sights. The secret to avoiding nightmares is to plan, remember the basis and execute, notes Glenn Nice, Purdue University weed control specialist.

“We think crop rotation helps,” Nice says. “It will not only help fight off weed resistance to key herbicides, but also may help with weed control.”

Good weed control requires setting the sprayer correctly and picking the right nozzles. “It’s easy to forget about nozzles,” Nice says. Yet they’re critical to getting the herbicide on target and avoiding drift.

Key Points

Plan a strategy that keeps you ahead of weeds.

Your weed control plan should be flexible in case weather interferes.

Residual herbicides earn a place in glyphosate, glufosinate era.

Air induction nozzles help immensely on drift, Nice says. Yet he notes that you can’t get so caught up in reducing drift that you forget good weed coverage.

Good foundation

“The first thing to know about residual herbicides is to use them!” Nice says. “They help on resistance, plus they expand your window for getting on post applications without suffering yield loss.”Early weeds tie up nitrogen and rob yield, Nice says.

“We can help you plan to control weeds early, but yet be flexible if the weather doesn’t work out,” says Tim Keller, corn and soybean residual herbicide project manager for Dow AgroSciences. SureStart, his company’s lead residual product, contains three modes of action and protects Roundup Ready corn up to six weeks.

“You can apply it from early preplant until corn is 11 inches tall,” Keller says. That flexibility helps deal with weather delays.

For example, plan to lay down the residual, then come back with glyphosate or glufosinate, Keller suggests. But if all else fails, add the residual to glyphosate or glufosinate after the corn is up, and still get control.

In soybeans, Keller recommends an early preplant residual application, such as Sonic in their lineup. It must be applied before soybeans emerge.

“If you miss that window, then use products such as FirstRate that can be applied with glyphosate or glufosinate,” he says.

Other options

“Our recommendation is Prequel pre-emerge as a residual,” says Todd Robran, product manager for DuPont. “You get multiple modes of action for weeds such as lambsquarters and waterhemp.”

Come back with a planned pass of glyphosate. Prequel will not be marketed in Wisconsin or Michigan.Resolve Q plus glyphosate can provide burndown and a residual in no-till.

You can spray V2 to V3 corn post with Abundit (glyphosate), Resolve Q or Realm Q.

“Get your residual down for soybeans while you’re planting corn,” says Susan Macy, soybean herbicide portfolio manager for DuPont. “That residual application should hold through planting, so you can come back with glyphosate later.”

For soybeans, the residual Macy recommends is Envive, which can be applied up to three days after planting. It helps with glyphosate-resistant weeds, she notes.

If you don’t get a residual down, she suggests adding a broadleaf product, such as Synchrony XP, with glyphosate to help on late marestail, velvetleaf and lambsquarters in Roundup Ready soybeans.


Nightmare! This is what you don’t want to see on June 15. Herbicide management tips and programs devised by various companies are geared toward controlling weeds as early as possible.

This article published in the May, 2011 edition of INDIANA PRAIRIE FARMER.

All rights reserved. Copyright Farm Progress Cos. 2011.