Three keys to managing root rots in your peas

Michael Harding shows a group of onlookers a diseased pea root at a recent Alberta Pulse Growers crop tour in Three Hills.
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Managing root rots comes down to “three key pillars,” says Michael Harding, research scientist with Alberta Agriculture and Rural Development.

The first is field selection.

“If you have a piece of land that has a heavy textured soil and doesn’t drain very well, that may not be a good spot to put peas.”

Next is getting the crop off to a “good healthy start.”

“The quicker you can get a healthy seedling up out of the ground photosynthesizing, the better off your crop is going to be,” he said.

“The longer it stays under the ground, struggling to get up in cold, wet soil, the longer the fungus has to find the crop, colonize, and start causing damage early on in the development of the seedling.”

Using high-vigour seed that has good germination will ensure the plant emerges as quickly as possible. Agronomy practices that help the crop get established early — proper seeding depth along with the right soil temperature, fertility, seeding rate, and herbicides — also help.

“If you’re seeding into cold, wet soil, that’s going to be a disadvantage,” said Harding. “If you’re seeding them deep and the crop is struggling to get up out of the soil, that’s more time for the root rots to set up shop.”

Seed treatment is another critical factor that will give the seedling “a competitive advantage for the first couple of weeks.”

“Using a seed treatment is to your advantage; not using it is to the advantage of the fungus,” he said.

“Seed treatments are not the answer to eradicating the problem, but those seed treatments do a lot in those first two to three weeks underground.”

The last piece is avoiding stress in the emerging crop.

“Anything that causes stress to your developing crop can help that root rot and give it more time and ability to get in and cause more damage,” he said.

Management practices such as rolling the land at the wrong plant node stage, seeding too deep, or seeding too early can stress an emerging plant. Sometimes, producers can even worsen a root rot infestation by spraying herbicide, said Harding.

“We’ve heard a lot of anecdotal information that this can be a predisposing factor to driving root rot a little harder,” he said. “Stressors on the crop can play to the advantage of root rot, so theoretically, it could be a factor.”

That’s where it gets “really tough” for cultural management practices, said Harding.

“There’s reasons to seed deeper. There’s reasons to roll your land,” he said.

“But it’s important to understand from the root rot side of it, some of those things play into the advantage of the fungus.”

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