Fighting wild oats is like herding cats, trying to swallow the ocean, and other impossible feats.
And thats was true even before herbicide resistance in wild oats began to increase.
But help is on the way as an Agriculture Canada team explores new ways to fight this nefarious weed, which has been ranked as the biggest crop pest in Western Canada since the 1970s. In a single year, Prairie grain growers spend half a billion dollars controlling the weed, said Neil Harker, research scientist with Agriculture Canada in Lacombe.
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So researchers are trying to determine the best ways to control wild oats without using herbicides, including options such as high seeding rates, winter cereals or early-cut silages.
“You’ll get a pretty good hit on most of them, but you won’t get them all,” said Harker.
One of their experiments explored the role of early-cut silage. Cutting silage a week or two early is more effective in controlling wild oats when compared to growing three years of barley with full rates of herbicide, said Harker. Cutting silage early results in a loss of about six to seven per cent of dry matter, but there’s still an increase in grain quality and protein.
“We lose a little in yield, but gain a little in wild oat management,” he said.
High wild oat populations in cereal silage can result in a loss of energy, so some producers will control wild oats even when fields are going to be silage.
Bumping seeding rates of barley from 250 to 400 seeds per square metre was found to inhibit wild oats. Reducing tillage, and making sure that wild oat seeds stay on the surface also slowed down the growth of the weed. Seeds that remain on the surface can still live for a couple of years and may be eaten by carabid beetles and mice. The seeds are also subject to frost action, drying and wetting.
“A lot of them will do lethal germination and will germinate in the fall if there’s moisture and then die over winter,” Harker said. “If they’re buried and they don’t receive the light signal, they will just sit there and wait for the right conditions.”
The wild oat situation in Alberta is exacerbated by the continuous growth of summer annual crops.
“We’re growing spring canola, wheat, barley, peas and lentils,” said Harker.
“Wild oats are a spring/summer annual. Until we rotate into a perennial or a winter annual such as winter wheat or fall rye, we really can’t put any pressure on wild oats.”
When plants are seeded in the fall, they can compete with wild oat populations. Fall ryes can get a jump on wild oats and contain chemicals that inhibit the growth of other species. Researchers are also planning to rotate plots between winter cereals such as winter wheat, triticale and fall rye.
“Three years without a summer annual crop will likely reduce our wild oats so that there’s very little need for control after three years,” he said.
This respite will last for a couple of years before wild oats appear again.
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“You’llgetaprettygoodhitonmostofthem,butyouwon’tgetthemall.”
NEIL HARKER
