Farmers are urged to watch for a new root rot pathogen this year.
“It is of particular concern because it’s very difficult to manage,” plant pathologist Sabine Banniza of the University of Saskatchewan’s Crop Development Centre said about Aphanomyces euteiches.
“Aphanomyces is a new problem here and it’s quite a tricky problem.… It’s a pathogen that’s very well adapted to very wet soils, so flooding is just perfect.”
Banniza, who spoke at CropSphere in Saskatoon Jan. 13, has been part of a pulse research group in the province since 1998 focused on disease management strategies and resistant breeding activities.
Continuous wet years, which started about 2009, have resulted in a prevalence of root rot. It is caused by a variety of pathogens, including fusarium, rhizoctonia and pythium.
Thirty-eight percent of 144 pea fields surveyed experienced root rot in 2009, followed by 29 percent of 112 fields in 2010 and 87 percent of 29 lentil fields in 2011.
Aphanomyces was first confirmed in Saskatchewan in 2012. The fungus-like organism was verified in 11 municipalities in 2013, and 72 percent of 18 lentil fields had it last year.
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“It is quite widely distributed, which suggests to us that it has really been around probably for a very long time, and what triggered it to become a problem have been these really wet springs.”
Banniza said peas and lentils are most susceptible to the pathogen, but it can also infect other pulse crops.
Effective management tools are limited with current varieties and basically involve rotation.
“At least right now there are no highly resistant varieties out there,” she said.
“Unfortunately with Aphanomyces euteiches, we don’t really have an effective seed treatment right now.… There’s a misunderstanding among growers in controlling root rot. There are growers who think they can grow lentils instead of peas and will be fine.”
The pathogen is widespread, but it may not be in every field. Initial soil sample research has shown that the pathogen is prevalent from the surface down to about 20 centimetres or more.
“I believe that soil testing (in wet conditions) will eventually be a major tool in risk assessment and a tool for farmers to make a decision, whether to grow a pea or lentil crop in this soil,” she said.
Banniza said crop rotation is the only thing that works because of the pathogen’s persistence in soil.
“Because it’s so persistent it means very, very long rotations (six years) away from the susceptible crops of peas and lentils,” she said.
Fababeans and chickpeas are alternative crops that have good partial resistance. Soybeans will also work if the seasons are long enough.
Farmers and seed companies have concerns about the difficulty marketing Saskatchewan-grown fababeans and chickpeas, but Banniza said there is still good reason to include them into rotations in light of the pathogen and wet conditions.
“I think there will be a lot of movement on this now because I think the industry has realized that we probably have to have fababean as an alternative crop here in the province.”
william.dekay@producer.com