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Dicamba drift not a problem in Manitoba this year

There are many ways to mitigate drift, but using the right spray nozzles is one of the most critical

Terry Buss, Manitoba Agriculture’s farm production extension specialist for pulses, explained dicamba drift on susceptible soybeans last year at the Crop Diagnostic School at Carman, Man.

For the second straight year dicamba drift, which has damaged millions of acres of crops in the United States, hasn’t been much of a problem in Manitoba, officials say.

While there’s pressure to further regulate the broadleaf weed killer in the U.S., that’s not the case in Canada.

“We’re aren’t seeing an awful lot of cases (of dicamba drift) at this time, which is a good thing,” Pratisara Bajracharya, Manitoba Agriculture’s pesticide minor use and regulatory specialist said in an interview Aug. 29.

Health Canada, which regulates pesticides in Canada, recorded just two incidents of dicamba drift in Manitoba in 2017 and 2018 involving five sites, a Health Canada official wrote in an email Aug. 31.

“Overall, Health Canada has received 18 incident reports, involving 35 sites, related to dicamba drift in Canada, the majority of which were in Ontario,” the email states. “Health Canada is monitoring the situation and will take action as necessary.”

Dicamba has a reputation for volatility. However, Monsanto (recently purchased by Bayer), and BASF, have developed less volatile versions of the weed killer to be used on dicamba-tolerant soybeans and cotton. Nevertheless, millions of acres of American crops have been damaged by dicamba.

Only 13 Canadian cases of dicamba drift related to an application on Roundup Ready 2 Xtend soybeans have been reported to Bayer Canada, Crop Science Division this year, Trish Jordan, the company’s public and industry affairs director, said in an interview.

“It’s pretty small when you consider the acreage,” she said. “It’s very similar to what we had a year ago, but the acreage is up.”

Triple rinsing the sprayer tank after applying dicamba is critical, especially before spraying soybeans that aren’t dicamba tolerant. The second rinse should include ammonia. These soybeans were sprayed after the tank was just rinsed once after applying dicamba. photo: Allan Dawson

Xtend soybean plantings in Western Canada (mostly Manitoba) were up 32 per cent from last year to 259,000 acres in 2018, Jordan wrote in an email.

Plantings in Eastern Canada were up 45 per cent to 649,000 acres.

The dicamba experience is different in United States. Plantings went up in 2018 and while the number of dicamba-damaged crops declined, weed scientists estimate 1.1 million acres of non-dicamba-tolerant soybeans were affected, the electronic newsletter Ag Insider reported July 16, citing a University of Missouri report.

Still, that’s down from 3.5 million damaged acres last year.

Arkansas had so many dicamba drift complaints in 2017 it banned spraying the herbicide on row crops this growing season, Ag Insider said.

Missouri and North Dakota restricted dicamba applications to earlier in the season.

The Environmental Protection Agency (EPA), which regulates pesticides in the U.S., required special training for applicators in 2017, limited the time of day when dicamba could be used and prohibited spraying when winds exceed 10 m.p.h., Ag Insider said.

Meanwhile, in an Aug. 29 letter to the EPA the Association of American Pesticide Control Officials (AAPCO) wrote: “An early-season cutoff date (for applying dicamba) should be mandated… but only if states are allowed to modify the cutoff date to adjust for state-specific conditions such as growing season or weather conditions.”

The letter says the high number of dicamba drift complaints is costing state regulators a lot of money and is “unsustainable under the current funding structure… ”

The AAPCO says dicamba’s registration should be reviewed every year to allow for label changes as new information becomes available.

The EPA gave dicamba a two-year registration in 2016 so the herbicide will soon be up for review.

Health Canada has no plans to change the rules for using dicamba in Canada.

“Health Canada is aware of the recent issue surrounding the use of dicamba and concerns with drift in the United States,” the department said in an Aug. 29 email. “To protect the environment, Health Canada has already mandated that labels of dicamba products include spray drift precautions, use directions and buffer zones. The department is confident that these existing requirements address issues such as those identified in the U.S.”

Manitoba Agriculture pulse crop specialist Dennis Lange says Manitoba farmers grew more Xtend soybeans this year.

“Growers are using the technology,” he said in an interview Aug. 30. “I think that’s a good thing because being able to use these tools to help slow (herbicide-resistant weed) issues is a good thing. I think growers are becoming more aware of the drift issues.”

Weed experts say one of the best ways to delay the onset of herbicide-resistant weeds is applying herbicides with two different modes of action for killing weeds.

Potential drift isn’t the only concern, Lange said. Communicating with neighbours, employees and custom applicators about the crops they are growing is critical. Don’t assume all soybean fields are dicamba, or even glyphosate, tolerant.

“You’re still going to have to be aware of a few things such as making sure the field you’re spraying is the right field,” he said.

“Nowadays custom applicators… cover a lot of acres in a very short period of time. Both parties have to ask the question what’s around the field and they have to be forthcoming with the information. Don’t assume the guy coming out and spraying is going to know what the neighbour’s field is.”

The best way to avoid dicamba injury is to apply early in the growing season, use the right nozzles when winds are light and triple rinse the spray tank, including using ammonia during the second rinse, Adama Pfeffer, Bayer Canada, Crop Science Division’s technology development manager said in an interview.

“The biggest challenge we had this year with off-target movement was again physical drift, improper nozzles, windy days, sensitive crops downwind,” Pfeffer said.

Large spray droplets reduce drift. That’s why Bayer recommends Turbo Teejet Induction (TTI) nozzles, he said.

“It just gives growers the largest flexibility to stay on label from a droplet-size standpoint,” Pfeffer said. “I would say that’s still our No. 1 gap in the marketplace — growers being aware that they have to upgrade their sprayer tips.”

Those nozzles require application rates of at least 10 gallons of water an acre.

Spraying should take place when wind speeds are three to 15 kilometres an hour and at sprayer travel speeds of no more than 24 kilometres an hour. Boom height should be no more than 50 centimetres, Bayer says.

“Early application (of dicamba) is important (on Xtend soybeans),” Pfeffer said. “It’s a great broadleaf weed control program. It has given us a second effect mode of action on buckwheat, kochia, cleavers. To me it’s the foundation of a solid weed control program in soybeans.”

About the author


Allan Dawson

Allan Dawson is a reporter with the Manitoba Co-operator based near Miami, Man. Covering agriculture since 1980, Dawson has spent most of his career with the Co-operator except for several years with Farmers’ Independent Weekly and before that a Morden-Winkler area radio station.



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