The dry conditions of early spring could lead to a spike in winter annual weeds.
“Winter annuals could be a problem,” said Neil Harker, research scientist with Agriculture and Agri-Food Canada.
“We really haven’t had a lot of spring moisture, so the ones that were already established, like stinkweed and flixweed and winter annual cleavers, might be a bit more of a problem than in other years.”
For some growers, “it might already be too late” to manage winter annuals, he said.
“For the winter annuals, we want to make sure they’re burned off prior to seeding or very shortly after,” said Harker. “Winter annuals will be at a pretty sizable growth stage by now, and they become less and less susceptible to herbicides the larger they get.”
Producers can also expect to see some problems with “the usual suspects on the Prairies — wild oats, wild buckwheat, green foxtail.”
“They’ve traditionally been the No. 1, 2, and 3 weeds across the Prairies, and I don’t see any reason why that would change.”
Just try to spray them as soon as possible, he said.
“The weeds that emerge with the crop and shortly after the crop are going to be the most damaging to the yield. With some of the second flushes, unless they’re really heavy, we don’t need to worry about as much as the ones that come up with the crop or around the crop.”
Harker is also seeing a rise in herbicide-resistant weeds — and that’s the bigger concern.
“We’re getting more and more Group 1 and Group 2 resistance to wild oat, and in the southern parts of the Prairies, we’re getting more and more kochia that’s spreading that’s both Group 2 and Group 9 resistant,” he said.
And the only way to manage that is to change up rotations — both in herbicide groups and in crops.
“Even though it might seem to be a bit of a short-term financial or profit hit to grow something other than canola or wheat, in the long term, it’s going to be advantageous in terms of delaying herbicide resistance,” said Harker.
“Until we’re willing to move away from some of the most dominant rotations, it will be difficult to get that kind of herbicide diversity that we need.”