A court in the United States recently blocked sales of the herbicide in response to complaints, but the ruling doesn’t apply to Canada
Dicamba drift may be a controversial issue in the United States, but it hasn’t been a significant problem in Manitoba, says a weed expert in the province.
In Manitoba, which has more than one million acres of soybeans, the number of cases of dicamba drift has been minimal.
“Because we’ve been very proactive and … because we have a different set of weather scenarios than they do further south, the number of reported incidents have been really low,” said Tammy Jones, Manitoba Agriculture weed specialist.
“From my impression, through my industry contacts, is there are some (incidents), but they are very limited.”
The herbicide, which can be sprayed post-emergence on Bayer Xtend soybeans, has become a legal quandary for U.S. growers and Bayer.
A U.S. court recently ruled that the U.S. Environmental Protection Agency understated the risk related to dicamba and drift of the herbicide. The ruling temporarily blocks sales and “vacates current U.S. registrations of certain low-volatility dicamba products, including XtendiMax,” Bayer said in a statement.
XtendiMax with Vapor Grip technology is a dicamba product, owned by Bayer.
On June 8, the EPA issue a cancellation order detailing how U.S. farmers can use existing stocks of dicamba products.
Growers and commercial applicators may use existing stocks that were in their possession on June 3, 2020. The use of dicamba must follow the label and must stop July 31.
The U.S. court decision has no impact on the use or registration of dicamba herbicides in Canada.
“We stand behind the safety of our products, including dicamba, which is an important herbicide for Canadian farmers,” Bayer Canada said in an email.
Dicamba drift became a massive story in 2017 when U.S. growers reported hundreds of cases of damage to neighbouring crops. The University of Missouri estimated that 3.6 million acres of soybeans suffered off-target damage and there were 2,700 complaints across the U.S.
Drift of dicamba and volatility caused injury to soybean fields that didn’t have the Xtend trait, in which soybeans can tolerate glyphosate and dicamba herbicides. The off-target damage also affected horticultural growers in the U.S., hurting fruit crops, vegetables and nursery trees.
In response to the problems of 2017, the U.S. Environmental Protection Agency introduced label changes to dicamba:
- Spraying only when wind speeds are below 16 km-h.
- Require dicamba specific training for all certified applicators.
- Dicamba can be applied only at daytime hours to avoid temperature inversions.
A number of states created calendar deadlines for dicamba use and some said it can only be used when air temperatures are below 30 C.
Adding to the legal confusion in the U.S., this winter a jury ordered Bayer and BASF to pay $265 million to a peach grower in Missouri who claimed that dicamba drift destroyed his orchard.
Nothing comparable has happened in Manitoba, possibly because the risk of drift is much lower in Manitoba’s cool climate and because soybean producers, who grow Xtend beans, are spraying dicamba early in the season.
“(I) would suspect there hasn’t been a lot of times where a later-in-the-season (in-crop) application has happened with a dicamba formulation. It’s typically (done) early,” Jones said.
If dicamba is sprayed very early in the season, drift damage is less likely. Susceptible crops are still in the ground or just emerging.
The recommendation is similar in Ontario.
“Even though there is a registration for post-emerge applications, the consistent message has been … use them in the pre-plant, pre-emergent window,” said Mike Cowbrough, weed specialist with Ontario Agriculture. “(And) appropriate nozzles, speed, temperature — are you in a (temperature) inversion (and) wind speed?”
Some soybean growers don’t use dicamba because they don’t have problems with glyphosate-resistant weeds. As a result, a number of producers may buy Xtend beans because they like the varieties and not spray dicamba.
But in certain regions of Ontario, dicamba is an important weed control tool.
“In the southwest … where we have glyphosate resistant Canada fleabane … there would be a considerable amount sprayed,” said Horst Bohner, soybean specialist with Ontario Agriculture.
Other soybean growers may avoid dicamba because of the legal risk.
“You see regions like the Niagara, where growers are very reluctant to use that technology at all because they are surrounded by vineyards and greenhouses,” Cowbrough said.
Ontario’s environment ministry tracks pesticide complaints and may have data on dicamba incidents in the province.
The Western Producer contacted the ministry but it didn’t provide the data as of press time.