To pea or not to pea, disease is the question

Abstinence makes soils grow fonder when it comes to pea yields, because it’s better to avoid fungal battles in the first place

EDMONTON — Limited options for dealing with root rot in peas means growers must develop new management strategies, says a plant pathologist.

Michael Harding, a research scientist with Alberta Agriculture in Brooks, said farmers need to adopt ways to avoid the disease instead of trying to eliminate it from their fields.

“We’re going to talk about avoidance because that is all we’ve got,” said Harding.

“We really don’t have any good varieties and any good chemistries yet to help us deal with this in the short term,” Harding told a recent meeting held during FarmTech in Edmonton.

Crop rotation isn’t new to farmers, but it is still one of the best ways to limit the impact of root rot in pulse crops, said Harding.

“These foundational principles are more important than ever.”

A one in four rotation is considered good management in all crops, but extending it to every five or six years in peas may help decrease the level of spores in a field already infected with pathogens that cause root rot.

Choosing the right field to plant peas will also increase success, said Harding. Heavier soil that is prone to flooding or highly compacted is ideal for disease growth and root rot.

Parts of the Prairies have had heavy moisture in June for the past two years, which adds to the increase in root rot.

“If it is wet and has extra soil moisture, that plays into the hand of root rot rather than into the hand of the producer,” said Harding.

“These pathogens love those conditions. Avoiding these kinds of fields is important to managing these diseases.”

Harding also recommended using good quality seed that is disease free and has high vigour. The faster the seed is to germinate, the less likely it will be infected.

Good management also includes using a fungicidal seed treatment and appropriate inoculants.

“Anything you can do to avoid stress on the crop is going to play into the hand of a healthy root system. Anything that stresses the crop out is going to weaken it, and the root rot will be more severe.”

Agriculture Canada research scientist Syama Chatterton said surveys have found a “significant increase” in root rot from 2013 to 2014.

“They’re showing quite a range of disease severity levels,” said Chatterton.

The three main pathogens for root rot identified in the Alberta field survey were fusarium solani, fusarium avenaceum and aphanomyces euteiches.

The fusarium, which was present in almost every surveyed field, is an opportunistic pathogen and attacks wounded plants or plants under stress. The plant is most susceptible to fusarium at seed germination.

Aphanomyces is a new pathogen in Alberta and depends on water during its early development. It produces long-lived resting spores. No chemicals are registered for its control.

Chatterton said the survey allowed researchers to get a better understanding of the pathogens in Alberta fields.

Chatterton will conduct field trials this summer to look for root rot protection options, including possible chemical and biological control. Studies in Europe show biological seed treatment may have some benefit.

John Bennett of Saskatchewan Pulse Growers said the organization is exploring options for bringing better genetics into new pea varieties.

“My personal sense is that the companies are likely not to bring those technologies into the country until they can have a value capture model that would return money,” he said.

“There are some root rot tolerance in pea genetics. They’re not in Canadian genetics and how to get them there is a problem.”

Jason Eklund, a farmer from Mayerthorpe, Alta., said root rot hadn’t been a large problem for his pea fields until the past two years, when it became a significant problem in wet fields.

“We have started growing fababeans, and maybe we’ll add growing fababeans into a more regular rotation,” he said about land he might reclaim from soggy parts of his farm.

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