Objectives of the project:
A posse has been formed and funded to catch “the great grain robber,” also known as herbicide-resistant wild oats.
The resistant wild oat action committee, formed in 2020, now has $196,000 at its disposal provided by the Saskatchewan Wheat Development Commission, Saskatchewan Forage Seed Development Commission, Manitoba Crop Alliance and the Alberta Wheat Commission.
Almost 70 percent of wild oats on the Prairies display herbicide resistance, according to data from the committee. About 27 percent are resistant to Group 1 and 2 herbicides, 62 percent are resistant to Group 1 only and 34 percent are resistant to Group 2 herbicides only.
Wild oats with resistance to more than one herbicide group are “particularly troubling,” said committee chair Eric Johnson, who is research officer of crop imaging and agronomy at the University of Saskatchewan.
Speaking at a recent Agronomy Update webinar session, Johnson told participants that multiple resistance shows “you won’t spray yourself out of a problem.”
Tank mixing Group 1 and Group 2 herbicides is not generally recommended, he said, because they can be antagonistic. A better option may be to layer wild oat herbicides by applying a soil-active pre-herbicide followed by an in-crop herbicide from a different group.
Johnson cited preliminary U of S research into higher seeding rates of wheat followed by a soil-applied herbicide and then further measures.
“The idea would be that the pre-herbicide would provide 70 to 85 percent control of the wild oat. Yet another 10 percent suppression due to the higher seeding rate, and then use the precision cultivation or the precision non-selective herbicide application to control any escapes that would produce seed.”
The pace of that research has been slowed by the pandemic, Johnson added.
Other studies involve use of quinclorac when applied to wild oats before the flag-leaf stage. Preliminary results indicate this reduces seed yield and results in smaller seeds, though its effect on germination, viability and seed vigour is not yet known.
Though growers wouldn’t likely spray quinclorac just to manage wild oats, it could be a side benefit if they use that chemical in a mix to control cleavers, for example.
Winter crops compete with wild oats, so that is another option, he said.
“Winter crops such as winter wheat and fall rye, they’re highly competitive with wild oats. They’re not widely adopted. They’re not for everyone.
“However, I know a number of growers that have successively integrated winter crops into their cropping systems and if you’re having issues with wild oats, certainly it would be worth taking a look at trying to integrate that in your cropping system.”
Johnson noted Canada is the second largest producer of tame oats in the world, and this is done without the use of wild oat herbicide.
“Successful oat production really fully relies on cultural practices.”
The action committee has developed several infographics to help producers identify herbicide-resistant wild oat problems and describe how and where they can have samples tested. These are available at weedscience.ca/wild-oat-action-committee.