New information showing the rapid evolution of clubroot disease types that can overcome the resistance built into new canola varieties is shocking.
It proves the danger that short canola rotations present to individual growers and the whole canola industry.
It also illustrates the wrongness of an attitude creeping into some farmers’ minds that they can ignore rotations because technology will ride to the rescue whenever disease or insect problems arise.
And it also highlights the need for improved alternative crops so that farmers can extend their rotations without reducing profits.
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Clubroot, a soil-borne disease, has become a significant problem in central Alberta in the short 12 years since it was identified in Canadian canola, with potential to severely reduce yields. And it’s spreading.
Seed companies rushed to develop canola varieties resistant to the disease with the first types introduced in 2009. But already the resistant varieties are losing effectiveness.
Last year, a strain of the disease, dubbed 5X, with the ability to overcome resistance was identified in Alberta.
This year, Stephen Strelkov, a plant pathologist with the University of Alberta, identified nine more strains capable of overcoming existing resistance.
He believes the outbreak is the direct result of growers pushing rotations and planting the same clubroot resistant variety every couple of years on a field or even in back-to-back years.
Strelkov said resistant varieties are holding in most of the fields in parts of Alberta where the disease is most prevalent, but it won’t last long if farmers continue to tighten rotations.
As well, expansion of new virulent strains complicates breeding.
Given the seriousness of the disease and the lack of a chemical tool to fight it, industry experts have developed a management plan.
The emphasis is on improved rotations and sanitation: cleaning field machines as they leave contaminated fields.
Crop rotation will not prevent introduction of the pathogen, but it slows its buildup. One-in-four year canola rotations along with rotating resistant varieties are recommended in clubroot risk areas.
However, farmers have shortened canola rotations in recent years because the crop is usually one of the most profitable.
To stem the trend toward short canola rotations, farmers need access to additional profitable alternative crops, reducing the urge to over-rely on one crop.
So it is good to see new investment an-nounced in corn and wheat development.
Canada’s Canterra Seeds and French co-op Limagrain are tightening their relationship, creating Limagrain Cereals Research Canada to develop new cereal varieties with a focus on wheat.
Canterra is also partnering with Alberta Wheat Commission to support Agriculture Canada’s Canada Prairie Spring Red wheat breeding program at Lethbridge.
As well, DuPont Pioneer has a new corn breeding facility in Lethbridge, which will focus on developing varieties that will mature in 68 to 69 days to match growing requirements for parts of Western Canada south of the Yellowhead Highway.
Crop rotation is critical to preventing the buildup of clubroot and all serious disease and insect pests in all of Western Canada’s crops.
As a result, farmers need even more crop breeding investment to provide a stable of profitable crops, — oilseeds, cereals, pulses and forages — to rotate among to guarantee the long-term sustainability of prairie agriculture.
