Dicamba finds new role in resistant kochia battle

Old herbicide keeps going and going | Glyphosate-tolerant kochia first found on Prairies last year

An old herbicide is playing a major role in the war on glyphosate and ALS-inhibitor tolerant kochia.

“Dicamba has been one of our main tools to control it. We’re learning more about it now,” says Curtis Thompson, an extension weed specialist and researcher with Kansas State University.

“I guess we have a couple of years head start on you folks up there.”

American growers have been dealing with glyphosate tolerant kochia since 2009. The problem was first found in Western Canada last year.

Thompson said controlling kochia with dicamba in cereals is working well, provided the applications take place early in the season and accompanies the glyphosate burnoff.

“Mixing in the tank (with glyphosate) is giving us some good foliar control, and we’re finding out that we are getting some excellent pre-emergent activity from those early applications, but let it get more than two inches high and you lose that 90 percent-plus control,” said Thompson about kochia control in corn and wheat.

“If it gets past you, well, it just plain gets expensive.”

He said producers in his region are looking forward to having more herbicide resistant genetics in their crops because there aren’t many lower-cost herbicide solutions for the pest in broadleaf crops.

As a result, farmers are welcoming the news that dicamba tolerant soybeans are expected to be available in North America in time for the 2014 growing season.

Canadian approvals were granted this week for the dicamba portion of the new crop genetics package, which will be released by Monsanto.

Dicamba resistance will be stacked with the latest Roundup Ready 2 genetics to form the Xtend branded seed, provided regulators approve of the combination.

BASF’s dicamba has been around since the 1960s and remains a popular broadleaf weed tool for cereal crops, on its own as Banvel or as a generic product from Gharda. It’s most commonly found as a component of tank mixes and pre-mix products that offer multiple modes of action against a wide selection of weeds.

For Monsanto’s Genuity RoundUp Ready 2 Yield Xtend soybeans, producers will likely be accessing a new, lower volatility dicamba that BASF and Monsanto have been testing. It will be tank mixed with glyphosate for application in crop, or applied as part of the pre-seeding burn off, as Thompson suggests.

Both strategies have been effective in testing at Ontario’s University of Guelph for weeds such as glyphosate tolerant ragweed and fleabane.

The new formulation of the broadleaf herbicide should improve its effectiveness while reducing application rates, Paul Rea, BASF’s vice-president of crop protection in the United States, said earlier this year.

Bob Wolf, a former Kansas State agricultural application systems professor, said the dicamba component will come with application provisos, including strict nozzle choices for sprayers.

He said the crops and herbicides are being engineered to work together under a set of best practices.

“There have always been recommendations about nozzles, pressures, boom heights,” he said.

“To take advantage of the new reformulations of older products and the latest (pesticide) products, you need to follow them.”

Thompson said application timing is going to be critical when trying to control kochia.

“When we realized kochia wasn’t dying like it used to, we had to start thinking outside of the box. Most of our success has come with early application timing,” he said.

“You might even need two burnoff applications, if there is too much time between the early application and planting. It’s still going to be cheaper.”

Thompson said U.S. producers have found adequate post-emergent control in wheat, barley and triticale with a mix of pyrasulfotole and bromoxynil.

“But again, only if you are early,” he said.

Bayer sells this mixture as Husky in the U.S. and Infinity in Canada.

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