Have we hit peak pulse?
That’s a question Sabine Banniza is regretfully pondering after studying the root rot that devastated prairie pea and lentil fields in the 2010s.
“I think it’s a real game-changer for peas and lentils,” said Banniza, a Crop Development Centre researcher, during a presentation at the Prairie Grain Development Committee annual conference in Winnipeg Feb. 26.
To keep growing peas and lentils on a field, farmers will probably have to move to what growers in pulse-heavy areas would consider extremely onerous.
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“Long rotations away from peas and lentils, and that means six to eight years, maybe even longer than that depending on the infestation level … will be at the core of dealing with this disease.”
The specific root rot forming such a crippling challenge is aphanomyces. It is a management problem in Canada and France. The French have been struggling with it since 1993.
It goes wild in wet springs, which is why it became such a problem in 2010, 2012 and 2014. But it now doesn’t need saturation to unleash it again. Growers who have seeded peas after even six years on previously infested fields have found yellowed patches with root rot damage within their crop, Banniza said.
The disease will take advantage of future pea and lentil crops not only to cause damage in that year’s crop, but also to multiply its spore load in the soil. As time goes on the disease inoculation of the field will keep growing unless very long rotations are employed.
“It won’t be easy,” said Banniza, noting the problems in canola with clubroot and fusarium in a range of crops. Many farmers have hoped to grow peas and lentils more frequently in order to provide more breaks to canola, but that now doesn’t look possible.
It’s a sad situation for the two crops, about which there was so much hope for expanded acreage even just 15 years ago. Pulse promoters had hoped to get pulse acreage to one-quarter of overall prairie acreage, but that now doesn’t seem likely.
Soybeans and chickpeas are two of the pulses that have resistance against aphanomyces, which is a blessing for western Canadian farmers.
But the only resistance to the disease found so far in peas and lentils is in France, where researchers have identified Aphanomyces resistance but have not released resistant varieties of crops yet, perhaps over fears that growers will overuse them and eliminate their effectiveness.
However, even when partially resistant varieties appear in Canada, it won’t be enough to control the disease enough to allow farmers to increase the frequency of pea and lentil crops.
“Even with good partial resistance, I think aphanomyces root rot management in lentil and pea will become the most complex disease management on the Prairies,” said Banniza.
Intercropping trials offer tantalizing suggestions that it can mitigate and minimize some of the impact of the disease, but more research is required.
“I think intercropping, mixed cropping, cover cropping may have the biggest potential in affecting aphanomyces,” said Banniza.
