Potential catastrophe looms as clubroot infestation rates soar

Provincial oilseed specialist Murray Hartman says the number of infested fields 
jumped by a third this year and will spread exponentially

The number of Alberta fields with clubroot jumped by more than one-third this year and provincial oilseed specialist Murray Hartman says exponential increases are likely unless canola growers lengthen their rotations.


“If the conditions are suitable, we expect to be seeing more cases every year,” said Hartman. “This year, we had the largest number of cases, and we should expect even more cases next year.” 


Canola growers could be in for a catastrophe if they don’t change their ways, said the Alberta Agriculture and Rural Development official. 


“Some of them are underestimating the impact of (clubroot) once it gets established,” he said. “If you ignore it, it will quickly build up in a field so that you have very severe yield losses. In some cases, these patches will yield nothing.” 


First detected in canola in 2003, clubroot was found in 1,500 fields this year, a sharp rise from the 1,100 fields last year, and it’s spreading by 20 kilometres annually. It’s akin to what happens in flu outbreaks, said Hartman.


“When the first couple of people get it, there’s a small increase in numbers. But after 100,000 people get infected, all of a sudden they’re infecting a lot of other people.” 


Many canola growers still don’t understand the threat posed to their biggest money-maker, said Scott Keller, who farms at New Norway, south of Camrose.


“The more we look for it, the more we find it,” said Keller, who found clubroot on two different farmers’ fields in the Camrose area in the fall of 2011 while working for an agriculture retailer.


“Before that, it was always somebody else’s problem. We were definitely in denial.”


And that’s still the case, as many producers are on a two-year rotation with canola, he said.


“We’ve been doing absolutely nothing about clubroot. We knew about it, but nobody was doing anything.”


Growers in the area, including Keller, have begun growing resistant varieties in an effort to manage the disease.


“The important thing now is to manage that resistance,” he said.


But that could be a tall order.


Growing a resistant variety will prevent clubroot from becoming established in a field. But if you sow a resistant variety into a field with a heavy infestation, the disease exerts “monumental increase” on resistance, said Hartman.


“All around the world, clubroot resistance in brassica crops hasn’t been durable, and we shouldn’t expect it to be any different here,” he noted.


That would pose a serious threat to canola production in Alberta, he said.


“If we don’t have any other good resistant sources, we’re going to have to really back off the rotation,” Hartman said. “And that won’t be good news.”


Keller aims for a one-in-three rotation for his canola, but “there’s definitely been fields where it’s been a one in two,” he said.


But extending the rotation to more than three years isn’t in the cards on his farm, he said.


“You look at what’s happened in the markets, and it’s pretty tough to get excited about growing wheat,” said Keller. 


Producers are “really toeing that line” between what makes agronomic sense and what makes economic sense, he says.


“Farmers aren’t going to do anything different until they start going broke.”


It’s recommended that producers pressure wash equipment before moving from one field to the next but that causes delays that producers can’t afford during the short spring seeding season.


“The conditions in the spring where the spores spread are the conditions where they’re going to have the least amount of time to devote to cleaning,” said Hartman. 


And many producers are still widely choosing non-resistant varieties because they’re cheaper.


“Producers are of the attitude that they’ll deal with it when it comes,” he said. “They’re looking at short-term economics and hoping that somehow the problem will go away.”


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