It’s time for farmers to recalibrate their approach to herbicides, especially in soybeans, says Daren Bohannan, technical representative for Bayer CropScience. “In the past, we waited until weeds were 3 to 4 inches taller than the crop and started spraying,” he notes. “We need a big shift in the mindset toward soybean herbicide programs.”

NEW MINDSET: “We’re all going to have to get better at looking at [herbicide] labels,” says Doug Maxwell, University of Illinois.

As farmers reach out for different chemistries in the battle against herbicide-resistant weeds, Bohannan says herbicide applications need to change, too. Why? Because Roundup is no longer an option against many herbicide-resistant weeds, and Roundup is a completely different chemistry compared to the herbicide options left on the table and future herbicide systems.

(See related story: The herbicide toolbox is shrinking.)

One tool farmers may consider for next season, according to Doug Maxwell, University of Illinois Weed Science Department, is the LibertyLink soybean system. “Remember, Liberty is not glyphosate," Maxwell says. “Liberty is a contact herbicide, and it does not translocate.”

That means spraying earlier, Bohannan says, and with more accuracy.

Accuracy will become even more critical in the future, Maxwell explains, as Roundup Ready Xtend soybeans with dicamba or Enlist with 2,4-D gain full approval. Roundup Ready Xtend soybeans still need approval for over-the-top dicamba use.  Enlist, with 2,4-D, glyphosate and glufosinate tolerance, is waiting for import approval from China.

Both systems will require more precise herbicide applications to avoid cross-damage and injury to surrounding nontolerant crops. “We’re all going to have to get better at looking at labels,” Maxwell warns. Labels provide important information on wind restrictions, nozzles, particle sizes and tankmixes.

That’s why Bohannan says farmers need to S.T.O.P before applying Liberty, or any herbicide.

What does S.T.O.P. stand for?

Start early. Control early-season weeds with a preemergence herbicide, and knock out escapes throughout the season, before weeds seed out.

Target small weeds. Spray weeds when they’re less than 3 inches in height. “Roundup was such an effective herbicide 20 years ago,” Bohannan notes. “Farmers adjusted expectations, waiting longer and longer to spray post applications.” It’s time to adjust timing and height expectations, and apply herbicide to smaller weeds, he adds. 

Optimize coverage. Check labels for the right rate, water volume and droplet size. Pay close attention to any nozzle changes that need to be made. “With Liberty, you want finer particles, more gallonage, more coverage on the plant,” Maxwell says. “The better you cover it [the weed], the better chance you have of killing it.”

Bohannan says a medium to coarse droplet is ideal for most herbicides. “Even glyphosate benefits from optimized spray patterns,” he adds.

Pair with residuals. It’s critical to use a broad-spectrum residual for multiple sites of action with pre and post applications, Bohannan notes. And he believes it’s time to forget about setup rates. “I don’t want a setup rate,” he says. “I want a good, strong rate that diminishes the population.” An effective preemergence program clears grass and broadleaves out of the way for the post program.

Maxwell says going into a field with just a few escapes after a pre herbicide program is ideal. “I don’t want to go out at 4 to 6 inches with 1,000 plants in a 5-foot area and try and kill all those weeds, because you’re not going to do it.”

Bohannan says all of these best practices get back to the basics of effective weed management. 

“These S.T.O.P. guidelines really should be applied to all herbicide programs, whether it’s Liberty or Roundup, or in the future, the Xtend, Enlist or Balance GT system,” Bohannan says. “If you follow these four simple guidelines, and pay attention to survivors — and make sure you eradicate those survivors before they reproduce seed — you win the game with any herbicide program.”