New study confirms wild oats worst weed in the West

The Oscar for the worst weed in Western Canada goes to — wild oats.

Farmers have always known the prolific weed was a yield reducer, but now scientists have ranked it the top weed problem in Western Canada.

“Wild oat is the most serious annual weed of field crops in Western Canada, costing growers millions of dollars annually in lost yield,” wrote John O’Donovan, Neil Harker, Kelly Turkington and George Clayton.

“In addition, herbicide costs amount to $500 million annually.”

In article in the latest issue of Weed Science, the scientists say wild oats costs millions in herbicides and is now growing more resistant to herbicide.

“Herbicides have traditionally been an effective way to control wild oats and reduce the amount of seed building up in the soil, but the extensive use of herbicides has resulted in more than 20 percent of crop land in Western Canada now having wild oat biotypes that are resistant to one or more herbicide groups,” the article reads.

The authors, who are weed scientists at Agriculture Canada’s research centres in Lacombe, Alta., and Lethbridge, said their study at four locations over four years showed that combining good cultural practices with herbicide can control the proliferation of wild oat seed and boost crop yields.

“The results of this and other studies clearly indicate that growers can adopt cultural practices that have the potential to make this goal a reality,” they wrote.

Integrated weed management has become an important factor in controlling wild oats in the field. It uses a combination of farming techniques, rather than one single solution, to find the best weed control and maximum yields.

The study compared several practices, including fields continually grown in barley versus fields rotated with barley, canola and peas; normal seeding rates compared with twice the normal seeding rates; semidwarf cultivars of barley compared to semidwarf cultivars mixed with tall varieties; and herbicides applied at 25, 50 and 100 percent of the recommended rates.

In the final year of the study, researchers found that the diverse crop rotation combined with higher seeding rates resulted in higher barley yields and reduced wild oat plants compared to continuous barley and lower barley seeding rates.

The combination of integrated strategies helped boost yields and reduce the amount of weed seeds in the soil.

Wild oat seed numbers fell 40 fold when optimal cultural practices were used in combination with the recommended rate of herbicide.

“The results indicate that combining optimal cultural practices with herbicides will reduce the amount of wild oat seed in the soil seed bank and result in higher barley yields,” the scientists wrote.

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