This causal agent of root rot is now widely distributed across Alberta. Research taking place in 2017 could eventually be the basis for an effective Aphanomyces risk assessment tool.
Alberta pea and lentil growers have long been accustomed to dealing with root rot. Recent years, however, have brought a game-changing new development.
It had long been believed that fusarium is the main causal agent of root rot in this province. Beginning in 2012, it emerged that Aphanomyces euteiches is another source of root rot, quite different from fusarium and potentially devastating in peas and lentils.
Between 2014 and 2016, disease surveys found that Aphanomyces is present in up to half of Alberta’s pea and lentil fields, with potential annual economic losses of $30 million in peas alone.
Despite the serious challenge posed by Aphanomyces, there’s a lot that scientists and agronomists don’t know about it. During 2017, Syama Chatterton will be working on a one-year research project examining how Aphanomyces infects peas and lentils. This work is supported by Alberta Pulse Growers through the Alberta Crop Industry Development Fund.
“This is a project that I started two years ago in Saskatchewan,” said Chatterton, Plant Pathologist with Agriculture and Agri-Food Canada in Lethbridge. “The question we want to answer is, how many oospores of Aphanomyces does it take to get the disease going?”
The role of soil characteristics
As Chatterton explains, one way to approach this question is to add Aphanomyces when you plant peas and watch what happens.
She’s also looking for any link between soil characteristics and the development of root rot via Aphanomyces. Based on her Saskatchewan experience, she believes there might be a connection. Soil conditions, however, are quite different between Saskatchewan and the different pea-growing regions of Alberta.
“We will be collecting soil from Lethbridge, Lacombe and Brooks,” Chatterton said, “and will see what happens if we add Aphanomyces oospores. It varies by location. Most exciting is that we’ve found that, in a particular field close to Lethbridge, no matter how many spores are present in the soil, we don’t get the disease.”
Today, root rots associated with Aphanomyces are one of the most significant threats to pea and lentil production in Alberta. In severe cases, this disease can reduce yields by 10% to 30%. If soil conditions indicated that Aphanomyces could be a significant issue in a given field in a given year, the producer could plant something else and avoid this risk.
In the long run, understanding the soil/disease connection could unlock new ways for producers to manage Aphanomyces-caused root rots or, in a worse-case scenario, make an informed judgment to avoid pulses for a while. The work being done by Chatterton this year could one day offer these management approaches to growers.
“Before we can develop detection methods, we need to know how many oospores are needed to start the disease, and how much is in the soil,” Chatterton said. “I think this is the foundational research that all future Aphanomyces research will build on.”
Project at a glance
Project title: Validation of infectivity model for Aphanomyces euteiches for Alberta
Project lead: Syama Chatterton, Agriculture and Agri-Food Canada
Total value of project: $168,870
Start date: November 2016
Completion date: December 2017