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Manitoba sees very limited dicamba drift

There were dicamba drift complaints in Manitoba, 
but nothing like in parts of the U.S.

There’s talk of restricting dicamba use in Arkansas following many crop injury complaints there this growing season, but there’s no such talk in Manitoba. Manitoba Agriculture’s Terry Buss spoke about a plot demonstrating dicamba drift damage at the Crop Diagnostic School in Carman in July.

[*UPDATED: Sept. 18, 2017] There’s talk of restricting dicamba applications in Arkansas and possibly other states, but not in Manitoba.

“I don’t think we are anywhere near the situation that they are having in the States (with dicamba crop injury complaints),” Manitoba Agriculture weed specialist Jeanette Gaultier said in an interview Sept. 7. “We seem to be in a much better situation, although it is still occurring.”

The University of Missouri says 3.1 million acres were damaged by dicamba, an older and more volatile herbicide that has renewed popularity with the recent introduction of Monsanto’s Roundup Ready 2 Xtend Soybean and cotton with XtendFlex® Technology — both of which tolerate dicamba and glyphosate.

To control dicamba drift Monsanto and BASF developed a dicamba formulation that’s less volatile.

The labels on both require farmers to follow a strict protocol when applying the weed killer.

But earlier this season the states of Arkansas and Missouri temporarily banned dicamba applications after a raft of complaints that dicamba drift injured nearby susceptible crops. Then last month Arkansas’ plant board recommended prohibiting dicamba applications after April 15 — a move Monsanto opposes, saying it’s not based on scientific data.

The U.S. Environmental Protection Agency is separately considering banning dicamba applications after a set deadline next year, Arkansas officials advising the agency told Reuters news service.

A cutoff date aims to protect plants vulnerable to the chemical. In Arkansas, the proposed April 15 deadline would also prevent most farmers from spraying dicamba weed killers on growing soybeans, a major selling point for the products.

*In an email Sept. 8 the Pesticide Management Reg­u­la­tory Agency said it would respond to questions about dicamba injury complaints in Canada next week (see update at bottom).

Arkansas had more dicamba complaints than other places because the state didn’t approve use of the new, less volatile dicamba formulations, Monsanto spokeswoman Trish Jordan said in an interview.

“We truly, truly believe their (Arkansas’) situation was made worse by the fact that, one, they never approved our (new dicamba) technology, and two, because it was never approved they had no training or education for growers in that process — none,” Jordan said. “That’s a big problem. It really shows how important that education and that outreach is.”

Just two states over in Georgia where farmers and applicators were trained to use the new formulations there were “virtually no complaints,” she said.

Almost all farmers in the U.S. and Canada had a positive experience with the new Xtend crops, and where there were problems, they can be corrected, Jordan said.

“I am very grateful we are not in the same situation (as the U.S.),” Gaultier said.

There have been 15 to 20 Manitoba cases of suspected crop injury due to dicamba drift or spray tank contamination, she said.

That fits with the 19 or so calls Jordan said Monsanto Canada received involving about 430 acres.

With Manitoba soybeans under stress from diseases and dry soils it was sometimes hard to figure out what was ailing the crop, Gaultier said.

In some cases dicamba-damaged crops can recover, especially if they are young, she said.

“I was surprised when I went back (to plots of non-Xtend soybeans sprayed with dicamba to simulate spray tank contamination) and looked at them weeks later and they recovered quite well,” Gaultier said.

Both Gaultier and Jordan agree there’s still room to reduce dicamba drift.

“The thing to do this fall and winter is to work together with Monsanto and BASF and agronomists and producers to try and refine those application methods that reduce the risks,” Gaultier said.

There are lots of hypotheses about why there were more dicamba complaints in the U.S. than Canada. For starters there were 25 million acres of Xtend soybeans and cotton in the U.S. versus 700,000 acres of Xtend soybeans in Canada — 250,000 in the West, most of which were in Manitoba.

“We exceeded our targets by quite a bit in Canada in terms of Xtend acres,” Jordan said. “In the East we were budgeting somewhere around 385,000 acres and I think we had 450,000. In the West we were almost double what we expected.”

Jordan also partly blames the media for keeping the story in the news and failing to put the complaints in perspective.

“What we’ve seen is 99 per cent of all farmers had a very positive experience with the technology,” she said.

But Jordan also said Manitoba farmers plant more wheat and canola than their American counterparts — two crops that are not susceptible to dicamba drift damage.

Manitoba is typically cooler and drier too, perhaps making temperature inversions less likely.

Monsanto says tank mixing and then applying herbicides such as dicamba and glyphosate, with two different ways of killing weeds, is a good way to combat herbicide-resistant weeds.

Weed scientists agree saying it’s more effective than rotating herbicides.

*Health Canada has not received any herbicide drift complaints, including due to dicamba, from Manitoba in 2017, André Gagnon, a media relations officer serving Health Canada and the Public Health Agency of Canada, said in an email Sept. 12.

In response to a question about whether the Pesticide Management Regulatory Agency is considering changes to dicamba’s label to mitigate drift, Gagnon wrote the following:

“Health Canada’s Pest Management Regulatory Agency (PMRA) completed a re-evaluation of dicamba in 2008 and concluded that products containing dicamba do not pose unacceptable risks to human health or the environment when label directions are followed. As an outcome of the re-evaluation, a number of risk reduction measures have been implemented on labels of all registered products to reduce potential exposure to humans and the environment. For example, as part of this re-evaluation, PMRA considered the impact of dicamba on non-target plants and revised the label directions including required buffer zones to protect non-target terrestrial plants and aquatic systems from spray drift. As well, mitigation measures are required to protect those with the highest occupational exposure levels. These include additional protective equipment, and reductions in quantity and/or concentration of the product.”

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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