By Tim Kalinowski
The old Roman proverb states: “In times of peace, prepare for war.”
Clubroot is coming to Southern Alberta sooner or later, says Alberta Agriculture and Forestry research scientist Mike Harding, and local farmers and ag fieldmen should be using the time they have to get all their ducks in a row.
“I feel like my job is the watchman on the tower to warn you about what’s coming,” he told the crowd 2020 Irrigated Crop Production Update conference in Lethbridge earlier this year. “I am here to tell you that clubroot is coming. It hasn’t stop moving, and it will be something we deal with eventually.”
Harding said Southern Alberta does have some natural defences against the protist spores which cause the disease, but these factors will not hold clubroot off forever.
“We have two things that really give us the advantage over clubroot. One is we don’t have the acidic soils they do in the parts of the province where clubroot is a real issue. And we are also semi-arid; so we don’t have the same amount of soil moisture most years. Because of our alkaline soils and our drier conditions, and some soils that just don’t hold a lot of water, it does give us an advantage against clubroot. But, clubroot can, and most likely will, end up in many of our Southern Alberta fields— and it will be something we have to deal with.”
Harding said total prevention is unlikely, but disease mitigation is a different story.
“Clubroot is not the end of the world,” he explained. “We’re definitely going to be able to manage it. We need to scout for it because catching it early before the resting spore populations get too high; that’s the key. And then using clubroot-resistant cultivars in a sustainable rotation is really a way to do that. If you don’t have many resting spores, or zero, a two-year resting break from canola works. A significant number of the spores die off in the first two years. And then the curve is really slow from there on.”
One practical tip farmers can implement now, stated Harding, is good sanitization protocols for cleaning equipment between fields to prevent the main way the disease is spread.
Researchers and farm technology companies are also working on other solutions to clubroot, he said, but the main problem remains the same no matter which approach you try.
“What’s the solution to getting ahead of it?” Harding asked rhetorically. “We need to be able to see underground. None of us can do that, but these were the ideas bouncing around in my head when I read a paper called, ‘Agri-Dogs: Using Canines for Earlier Detection of Laurel Wilt Disease Affecting Avocado Trees in South Florida.’
“With laurel wilt disease you can’t see any of the symptoms until it is too late, and see if they see symptoms of laurel wilt they cut the tree down and burn it,” he added. “So they need to be able to detect it early, and that’s where the dogs come in. You train dogs to recognize the scent of laurel wilt in avocado trees. And dogs were able to, 98 per cent of time, accurately determine whether a tree had an early infection.”
Harding worked with dog trainers Mario Bourque and Bill Grimmer this past summer on maybe applying the same idea to clubroot. Could dogs, he asked, be the early detection device needed to mitigate the disease’s earliest symptoms and reveal smaller swells in the roots beforre they become galls?
“What we learned was: There is no doubt dogs can detect clubroot by scent,” he summarized. “But to produce working dogs that would actually be scouting canola fields, there is additional work that would need to be done to basically show the dogs what it is they want them to do and how you want them to alert you.”
Harding said there are some dog trainers working on this type of scent training in Alberta (Bourque and Grimmer are from New Brunswick) as we speak, but it remains to be seen if early detection dogs can be the definitive answer or just one more tool on the belt in the fight against clubroot.
“This was a bit of discovery type of research; basically a proof of concept asking can dogs do this?
“The answer is ‘Yes.’ Dogs can detect by scent things in the parts per billion. They might be able to detect more than that, but our scientific and electronic instruments can’t detect more than that.”