Manitoba canola growers have heard all about the disastrous effects of clubroot on canola, how easy it is to spread and how difficult it is to manage.
At the latest CanoLAB canola management workshop here March 15-16, they heard about how to farm effectively if it’s already present.
Since 2003, when the first instance of clubroot in Canadian canola was reported near Edmonton, the count of infested fields in Alberta has climbed. Closer to home, anxiety has grown as fields in Manitoba have started testing positive for the pathogen.
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Holly Derksen, field crop pathologist with Manitoba Agriculture, said the conversation around clubroot has changed in the province over the last four to five years.
“The alarm has gone down,” she said. “Growers are a bit more accepting. They know they’re not alone, for one. They know they’re picking it up early, so it’s not like they’re seeing a yield loss and there are things that they can do.”
- Read more: Clubroot a Manitoba reality
- Read more: CanoLAB workshop makes Dauphin debut
Longer crop rotations, less tillage, clubroot-resistant crops and equipment sanitization are among the oft-repeated management strategies for clubroot across the Prairies.
Dan Orchard, an agronomist with the Canola Council of Canada from north-central Alberta credited with first discovering the disease in Canada, advised farmers to test their soils and avoid buying equipment from his home province, where he has seen spore counts up to a billion spores per gram. If Alberta equipment is imported, producers should arrange to have it thoroughly cleaned before shipping, for fear of spreading spores.
Soil tests, both he and Derksen said, should include five samples in a “W” formation for the most accurate results, as the pathogen may vary widely within a few feet. Soil-testing guidelines and protocols are published at www.clubroot.ca. Orchard said farmers need to understand if the disease is present in their fields, even at low levels, and take action if it is.
“They need to start deploying resistant varieties, making sure they reduce traffic in and out of that field, especially if it’s muddy and whatnot and maybe consider leaving out a different part of the field than the entrance all the time where most of the disease shows up,” Orchard said.
Clubroot is commonly found at field entrances where unclean equipment “wings out” and dumps potentially contaminated soil after transport, Orchard said. Leaving through a separate entrance may reduce the risk of tracking contaminated soil from field to field as equipment does not pass through the higher-risk area again when exiting.
Cleaning equipment between fields may also halt the spread, he said, although he acknowledged that many producers might resent the inconvenience.
“The better you clean, the better you are,” he said. “If you have no option to clean, I think you need to consider not entering that field when it’s going to be really muddy and sticky when you’re going to be dragging a whole bunch of dirt around. You can also farm that field last if you’re convinced it’s your only field with clubroot, so that you can have time to wash and clean that equipment at the end of the season rather than in between fields.”
While clubroot has been found in Manitoba, spore loads remain low compared to Orchard’s home turf in Alberta.
It is his hope that those lower spore loads will allow mitigation techniques to curb the problem from reaching the severity those farmers have suffered.
Research has suggested that rotating two to three years between clubroot-vulnerable crops will render 95 to 99 per cent of spores non-viable, Orchard said, an option that may not always be applicable in Alberta, where even one per cent of an extremely high spore load is enough to prove harmful, he told CanoLAB participants.
Likewise, he said, Manitoba may not face the resistance issues he has seen in Alberta, where new clubroot strains have emerged. Since 2014, 11 new clubroot strains have been discovered, the Alberta Farmer Express reported in September 2016.
“The genetics, when under high, high spore loads and heavy pressure, the pathogen finds a way around the resistance,” he said. “Here in Manitoba, the spore loads are so low right now that the pressure that would be put on a resistant variety would be so minuscule that it would take a long, long time to defeat that resistance.”
Manitoba is in the fortunate position of lagging behind Alberta in the clubroot saga, according to Derksen.
“We can learn from their experiences,” she said. “We know what worked, what didn’t work and we do have these (resistant) varieties. It is entirely possible to grow a highly successful canola crop even when you have clubroot in the soil.”
Randy Fingas, who farms near Inglis, Man., said he was pleased to see his region “in the green,” with soil samples below 10,000 spores per gram of soil, but expressed surprise over the number of RMs that have reported visible signs of clubroot.
“It’s always in the back of your mind. You think it’s in Alberta, but it’s here,” he said, adding that he found the CanoLAB presentation informative.
“The disease is in your soil, but it’s at such minor rates and the environment’s got to be right,” he said. “It’s got to be the right pH to promote it more. It was a lot of interesting facts.”
CanoLAB took place in Dauphin March 15-16, the fifth such workshop to take place in Manitoba.
