What will make the dicamba experience different for Illinois farmers in 2018?

University of Illinois weed scientists have some suggestions, and many revolve around volatility. Says Aaron Hager, “Volatility is a chemical process that obeys the laws of chemistry. It doesn’t obey a label.”

Those dicamba labels have additional restrictions in 2018, thanks to the U.S. EPA, which last fall mandated reduced maximum wind speeds, modified tank cleanout procedures and condensed spraying hours for XtendiMax, FeXapan and Engenia herbicides.

And while the Illinois Department of Agriculture has declined to implement additional restrictions, other soybean-growing states have restricted spraying dates, temperatures and more, even by county. Weed scientists at Iowa State University are discouraging farmers entirely from using dicamba, including the in-season formulations, in postemergence herbicide programs.

“This is based on their assessment of the risks of using dicamba in the postemergent window, which are pretty great as evidenced in 2017,” Hager explains.

He points to research that shows dicamba, in any formulation, can volatilize, and says that despite efforts to minimize off-target damage, volatility is the one thing restrictions can’t control. His often-repeated mantra regarding new dicamba formulations? “They’re ‘low’ volatility, not ‘no’ volatility.” Experience and research have shown that higher temperatures greatly influence volatility, which can occur as late as two or three days after application.

Related:Who’s liable? 6 things to know about dicamba for 2018

What can applicators do to reduce the risk of off-target movement?

Hager, along with Bill Johnson and Joseph Ikley from Purdue University and Mark Loux from Ohio State University, offers five additional recommendations to reduce off-target dicamba movement damage:

1. Watch the wind. If wind gusts exceed 10 mph, don’t spray dicamba. The updated labels clarify wind restrictions by requiring applicators to clock wind speeds at boom height.

“You can’t go off a weather station at some airport,” Hager says. “The only way to truly know wind speed at boom height is to use an anemometer.”

If an applicator doesn’t stop when wind speeds jump from 8 mph to 12 mph and off-target movement occurs, the applicator is responsible for potential damage, he says.

2. Run the boom low and slow. Label requirements call for a 24-inch boom height. Avoid running your boom into the ground by reducing speed. Keep sprayer speed under 15 mph, per label restrictions.

3. Avoid applications when temps reach 80 degrees F. Hager says this recommendation goes back to a weed control guide from 1985. “Temperature is one thing that increases the rate of volatility,” he says. “Anyone who reads ‘low volatility’ and thinks there’s a chance for that not to happen is a mistaken.”

4. Consider a cutoff date. IDOA did not set an in-season dicamba application cutoff date, but Hager and his colleagues recommend applying dicamba only as a preplant, preemergence or very early postemergence treatment. Why? Dicamba is less likely to volatilize in the cooler, early-season temperatures, and less vegetative growth may mean less potential damage. Wind speeds may also be lower earlier in the season, reducing the potential for drift.

More than 90% of the 2017 off-site movement complaints resulted from postemergence applications.

5. Talk to your neighbors now. LibertyLink beans? Conventional beans? Seed beans? You need to know what sensitive crops will surround your Xtend fields before application day arrives so you can make an informed decision. Application windows will be tight, and you won’t have time to track down neighbors on application day.

How tight is tight? Factoring in the 2018 label requirements, Purdue University calculates that west-central Indiana applicators would have had 48 hours to spray in June 2017. Hager says the application window in Illinois would have been just as narrow.

“Forty hours or 80 hours, applicators will be held responsible,” he adds. “The retail sector understands how tight this whole post-window application is.”