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A three-year research project produced some promising results for controlling kochia.
The work was led by Shaun Sharpe, an Agriculture and Agri-Food Canada weed scientist in Saskatoon, Sask. He worked with six producers around Last Mountain Lake, about an hour north of Regina, from 2021-2023.
There was success when burying the pesky weed before it could mature into a tumbleweed and move long distances.
He said the kochia seed bank is only viable for about three years.
“This is about 95 per cent of it. There will be a couple stragglers coming up later, five plus years, but 95 per cent of it is going to be dead due to natural decomposition in about three years. So, if we can pick up where it is and manage it heavily because these patches represent high densities of plants, that means we can apply mulch or something to bury it. Kochia doesn’t tolerate burial,” Sharpe said.
Sharpe applied different materials to patches of kochia. This included black plastic and wheat chaff. Hydro mulch, which is a slurry of seeds, mulch and fibre that’s used in erosion control, was also used.
Researchers also mowed patches of kochia.
“The chaff treatment I’m very, very excited about because chaff and straw is something every grower is going to have if they’re producing wheat and other grains. It’s something that’s potentially on farm that’s already at their disposal that we can either move around within a field or between fields. Cocoa mulch didn’t hold up quite as well as I was hoping, although it’s still decent. Then the mowing is effective, but it was taking three to five times per year,” he added.
Plastic had the best results but is not the most practical. The chaff had the second-best results with higher levels of control in the first year of the study.
The chaff can introduce other weeds to the kochia patch but Sharpe believes the benefits outweigh the negatives.
“In your chaff, unless you’re using a seed mill destructor, all the weeds that are in your field prior to harvest are now coming out in the chaff. There’s always the potential for that,” he said. “We’re hoping with the layering it’s going to prevent that and we’re going to see something else is not kochia, that’s OK with me, because you’re going to have additional competition in those patches from other weeds. Just like if you’re doing a cover crop or something like that.”
Sharpe is currently editing his research paper and hopes to have it published sometime next year. He has some advice on herbicide as a control method.
“I think you should use your herbicides on small plants. Anything outside the range on the label, please don’t,” he said. “Mow it and get it out of there.”
