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Ag scientist warns of clubroot in canola

Clubroot is a problem again this crop season in canola, of which North Dakota is the nation's dominant producer. Supplied photo

LANGDON, N.D. — Venktat Chapara knows a great deal about canola and canola disease. Now he's warning farmers in North Dakota's Cavalier County, where canola is widely grown, that clubroot could be reaching "epidemic status" there.

"The rapid increase in the number of clubroot-infested fields and the enormous potential for crop loss has raised concern," says Chapara, plant pathologist for the North Dakota State University Langdon Research Extension Center.

North Dakota dominates U.S. canola production, and canola is especially popular with farmers in the area around Langdon, the county seat of Cavalier County.

Clubroot, which can devastate canola yields,is caused by a soil-borne pathogen with the "characteristics of plant, animal and fungi for which there is silver bullet to control," Chapara says.

Once in the soil, clubroot can live up to 17 years, says Chapara, who's conducting ongoing research into the disease with the help of the U.S. Department of Agriculture and the Northern Canola Growers Association.

Clubroot was identified in Cavalier County in 2013 and has made an appearance every year since then. But it's particularly prevalent this year, Chapara says.

Already this year, it's been found in 22 fields in the county. "Let me ask growers, 'Do you think that's an epidemic?'," Chapara says.

"By the end of the season it may be in even more fields than expected," he says. "Continuing spread of clubroot is becoming a threat to canola production across the region in low-pH soil."

Chapara recommends an "integrated approach for sustainable management of clubroot." That includes practicing sanitation with equipment and boots, longer crop rotations of at least two or three years and using resistant varieties.

He recently returned from a conference in Edmonton, Alberta, where Canadians farmers' experience with the crop where examined. Canola was developed in Canada, which remains the world's largest exporter of the crop.

The conference gave him more insight into clubroot; Canadian canola farmers have struggled with the disease for years.

What had been clubroot-resistant varieties of canola in Canada lost most of that resistance within four years of their introduction, so U.S. canola farmers shouldn't expect disease-resistant varieties to provide a permanent solution here, Chapara says.

Another conclusion presented at the Canadian conference: Farmers shouldn't plant canola more than two years in five on the same field and ideally no more than one year in five, Chapara says.

Clubroot can infect only cruciferous plants, a group that includes cabbage, cauliflower, radishes, turnips and wild mustard.

Farmers with concerns about their canola can contact the Langdon Research Extension Center at (701) 256-2582 or the Cavalier County Extension office at (701) 256-2560, Chapara says.