Saskatoon researcher tackles soil-borne disease affecting canola

Bringing a glimmer of hope to farmers in Westman and across the country, a team of federal government scientists is studying how to protect canola and other plants from invasive clubroot, a soil-borne disease.

Fengqun Yu is leading a team of Agriculture and Agri-Food Canada (AAFC) scientists in Saskatoon who, for the last 10 years, have performed the most comprehensive genetic studies on clubroot in the world, helping to develop new resistant variants of canola and other crops that clubroot attacks, including cabbage, cauliflower, rutabaga and other plants in the Brassica genus.

The disease affects the root of the canola plant, so that they are club-shaped and unable to properly transport water. Clubroot can substantially reduce seed quality and oil content in canola, resulting in economic losses, and the chief concern of Manitoba producers is the longevity of the pathogen it leaves in soil.

It can survive for 10 to 20 years, even in the absence of a canola crop, Manitoba’s agriculture website says.

“Once the disease gets there, it’s very hard to get rid of it. It’s very difficult,” Yu said.

First noticed in the 2000s during an outbreak in Edmonton, clubroot has now spread across the Prairies through erosion, infected soil attached to farm equipment and too-frequent canola plantings. It has also affected other plant species east of the Prairies.

Diligent protocols, such as crop rotation and disinfecting equipment to stop the spread, have been a producer’s initial line of defence, but thanks to Yu’s research, it may soon be possible for producers to leave their clubroot worries in the dust.

Yu started working with AAFC’s clubroot team in 2011 as the expert in clubroot genetics. At that time, there was no canola germplasm (genetic material) resistant to clubroot at AAFC, but after a decade her group has identified more than 20 clubroot-resistant genes from the genus of plant species called Brassica that can be used by breeders for developing new cultivars.

Yu and her team have published 10 papers on clubroot genetics and have quickly shared these technological advancements with researchers who can apply them to their breeding programs.

“I am so excited to see that AAFC currently has abundant canola germplasm developed through our research program. There are lots of studies to be done and exciting discoveries ahead. More importantly, I am so glad to see my research can benefit growers of canola, mustards and vegetable production,” Yu said.

Yu’s team has also developed the first set of canola lines that carry identified individual clubroot-resistant genes, which could revolutionize the clubroot problem by providing crop breeders and growers with information they can use when developing or growing cultivars with increased clubroot resistance.

“There are different ways to manage it, but for me, I work on genetics control, which means finding a way for a grower to grow resistant varieties in the presence of disease.”

While it is possible to curtail the spread of the clubroot pathogen and reduce the incidence and severity of the disease through a combination of minimizing soil risk and using sanitation plans and diligent record keeping, working with clubroot-resistant variants of canola is the best way to keep fields safe from the devastation it can wreak, the Canola Council of Canada’s website says.

The Canola Council didn’t respond to a request for comment by press time.

Yield loss from clubroot depends on many factors, including time of infection, soil moisture and temperature, spore load, soil pH, soil texture and more. An early infection with favourable conditions and moderate to high spore loads can lead to 100 per cent loss, while low spore loads with less favourable conditions may result in little or no yield loss.

Depending on local conditions and timing of infection, clubroot-infected canola may look very similar to canola suffering from other diseases or environmental stresses. Patches of prematurely ripening canola due to clubroot infection could be confused with other diseases such as sclerotinia, blackleg or fusarium wilt, or moisture stress from drought or waterlogging.

Symptoms in the field will also vary depending on the growth stage of the crop when infection occurs, the severity of infection and environmental conditions after the infection takes place. Early infection, which happens at the seedling stage, can later result in wilting, stunting, yellowing and even death of canola plants at the late rosette to early podding stage.

Infection that occurs at later crop stages may not show plant wilting, stunting or yellowing, but infected plants may ripen prematurely, resulting in shrivelled seeds. Lack of moisture, high temperatures late in the season and other canola diseases can also produce similar symptoms, so to truly find out if a crop is suffering from clubroot, both above ground and below ground parts of the plants must be examined.

Comparing the spread of clubroot to the COVID-19 pandemic, Yu said she and her team still have a lot of work to do to deal with the rapidly spreading problem of clubroot.

“We’re still continuing to do the work,” she said. “We’re doing the legwork, and we’re always thinking about how to benefit the producers and the growers.”

This story was originally published in The Brandon Sun. It is republished under a Creative Commons license as part of the Local Journalism Initiative.