Clubroot not just another disease

The response to clubroot has been uneven and often ineffective, 
but we need to learn from what’s worked to prevent a crisis situation

What surprised me most while researching the origins and spread of clubroot was just how devastating this disease is.

Before travelling through the most affected areas and interviewing those at ground zero, I thought of clubroot as just another crop disease.

It’s not.

But unfortunately, many canola growers still don’t fully realize the threat they face.

The discovery of clubroot in an Edmonton-area field in the fall of 2003 seemed to come out of the blue. In fact, experts in the U.K. had been waiting for years for clubroot to make an appearance on the Canadian Prairies.

When it did show up, agronomist Dan Orchard only recognized the disease because of what he calls “dumb luck.” In university, he had written a paper on canola diseases and had to discuss three. He was at a bit of a loss because there were only two major canola diseases here — sclerotinia and blackleg — and he just happened to choose obscure clubroot because it was present in a few other areas of the world.

Even though Orchard was stunned by what he found — the growths on the roots of the infected plants were the size of grapefruits — he didn’t realize how serious it was. But after taking samples to his old plant pathology professor to confirm it was, indeed, clubroot, he took him to the infected field. That’s when the gravity of the situation became clear. If left unchecked, Orchard was told, clubroot could threaten the entire canola industry in the affected area.

Soon after, a press conference was held and that solemn warning was issued to the entire industry. But even today, many growers cling to the belief that plant breeders will come up with resistant varieties and the problem will be, if not solved, then easily managed. That clubroot is just another crop disease.

It’s not.

Resistance is a numbers game. Whether weeds or spores, a few have the genetic makeup that make them resistant to resistance. And the basic biology of clubroot is that a single gram of heavily infected soil can hold more than a million spores. When you have countless trillions of spores in a field, some will survive and rapidly prosper. This is why the first resistant variety, introduced in 2009, has already been overcome.

What is needed is an approach much like the one that public health officials use when dealing with a communicable disease, which is to take all necessary steps to limit the ability of infected individuals to spread it to new victims. For clubroot, that means enforcing a four-year or even longer rotation to prevent it from rapidly spreading.

However, because of a quirk in how local affairs are managed in Alberta, a lot of the responsibility for dealing with clubroot fell to agricultural fieldmen. They take their direction from the local government, and not surprisingly, rural politicians aren’t thrilled by the prospect of having to tell their neighbours what they can and cannot grow in their fields. This led to a patchwork of solutions, ranging from draconian policies that alienated growers to a laissez-faire free-for-all.

But one county stands out for its approach. Time and time again during my research, I was told to visit Leduc County because “they’re getting it right.”

Part of the county’s approach was realizing how serious the situation is and taking tough, but necessary decisions. But it’s also about very carefully communicating why measures like longer rotations are needed, and constantly reviewing the situation and adjusting policies as circumstances change.

As Orchard, who now works for the Canola Council of Canada, points out, preventing clubroot from undermining the entire canola industry means dealing with it head on. And that means learning “what we did right and the things that didn’t work out as well.”

Gord Gilmour is associate editor of Country Guide. His full article is in the September issue, which is available at country-guide.ca.

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