Integrated plan vital to slow spread of super weeds

WIU professor says application timing playing a role in dicamba-drift complaints.

Mark Bernards, Western Illinois University crop sciences professor, displays an injured soybean plant at a plot on the Ron Moore farm in Warren County during a field day hosted by the Illinois Soybean Association. (Photo by Daniel Grant)
Mark Bernards, Western Illinois University crop sciences professor, displays an injured soybean plant at a plot on the Ron Moore farm in Warren County during a field day hosted by the Illinois Soybean Association. (Photo by Daniel Grant)
By Dan Grant

Farmers should take a proactive rather than reactive approach when it comes to weed management, according to Mark Bernards, crop sciences professor at Western Illinois University.

Bernards, who specializes in weed management, encourages farmers to develop and follow an integrated weed-management plan on their farms.

Such a plan can not only improve the bottom line on farms, but it can also slow the spread of superweeds that developed resistance to multiple herbicides.

“The No. 1 thing you can do is prevent weeds from getting on your farm in the first place,” Bernards told farmers recently at the Illinois Soybean Association field day on the Ron Moore farm near Roseville in Warren County.

That’s a tall order, though, as weeds such as waterhemp spread millions of seeds via combines, tillage equipment, wind and wildlife.

Another problem weed, Palmer amaranth, popped up in pollinator habitats in recent years. The majority of counties with the problem in Iowa (35 of 48), two counties in Illinois, two in Ohio and one in Indiana first reported Palmer amaranth in conservation acres.

The weed seeds also spread through livestock feed along with bird seed.

So, what should farmers do to control pesky weeds?

Some weeds, such as marestail, should be managed in the fall or early spring. Cover crops have become an important tool to help suppress weed pressure, while tillage remains another option.

When it comes to herbicides, farmers should follow the labels and use full rates and multiple modes of action, Bernards noted. Timing of applications plays a key role as smaller weeds are much easier to eliminate.

“Think beyond herbicides,” Bernards said. “Herbicides are a great tool. But if all you rely on (for weed control) is herbicides, we’ll burn that tool up.”

One herbicide used much more this season, dicamba on Xtend systems, should only be used as labeled.

Bernards believes drift complaints this season are due in part to the timing of applications and contaminated sprayers.

“We’ve used dicamba in corn since the 1960s, so why are we struggling with issues in soybeans,” he said. “In corn, we applied it in late April or early May.

“With soybeans, we’re applying dicamba in June or even early July when it’s hot and humid,” he noted. “So we’re more likely to have temperature inversions.”

Bernards noted most of the dicamba-drift issues in his area have been isolated incidents.

“My observation is it’s relatively limited,” he added. “We’ve seen more volatility than perhaps expected in the southern U.S.”

IDOA receives 83 alleged dicamba complaints

As of July 20, the Illinois Department of Agriculture (IDOA) received 83 alleged dicamba violations out of 212 pesticide-misuse complaints, according to Rebecca Clark, IDOA spokesperson.

The complaints were assigned to IDOA investigators, and no official determinations have been made, Clark told FarmWeek.

Content for this story was provided by FarmWeekNow.com.

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