ST. ALBERT, Alta. — Crop disease specialist Robyne Bowness expressed a little discomfort as she stood in front of a perfect pea crop.
She was there to discuss disease, but as she surveyed the plots searching for disease to show those attending the crop walk at the University of Alberta farm north of Edmonton, there was none to be found.
“These plots are completely disease free,” said Bowness, an Alberta Agriculture crop disease specialist.
But the plots may not stay that way. A recent hailstorm left white marks on the pea pods. A weakened plant is more susceptible to disease and Bowness predicts the combination of moist, warm weather and weakened plants will be an invitation for disease.
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“Now that hail has hit, the disease will move in and it will move in quick,” said Bowness.
“Keep an eye on it because it’s going to move in fast.”
While these plots were disease free, Bowness used the tour to explain the main diseases that can affect peas.
Ascochyta complex is three pathogens working together. The first disease to show up in the crop, it starts at the bottom of the plant and works up the canopy. The airborne disease is spread by rain and rain splashed spores. A dry season will stop ascochyta from spreading.
Rotation and fungicide are the only ways to control the disease. Bowness, who said timing of fungicide is critical, recommends scouting pea crops twice a week to catch the fast moving disease.
Downy mildew is a relatively new disease that causes a grey, fluffly mycelium or fuzz on the underside of leaves. The disease has shown up in the Vegreville and Vermilion areas.
It generally hasn’t been a problem, except in affected areas where the impacts can be devastating. Fungicides do work on it. It doesn’t like heat and is usually gone by mid-July.
Sclerotinia or white mould attacks canola. With recent cool, wet weather, sclerotinia is starting to show up in pea crops and canola.
“It’s the same beast and will go back and forth between the two crops easily,” she said.
Sclerotinia causes a white bleaching of the stem and a white cottony mould grows on the stem and pods. It’s not a huge economic disease in peas, but will likely become a more serious problem as acres increase, she said.
Bowness recommends growing canola after peas because there are more fungicides registered for sclerotinia control in canola. Crop rotation and fungicide are the farmers’ main tools to fight the disease.
Bowness predicts fusarium root rot will soon become one of the pea producers’ biggest disease problems.
“So far, there have not been devastating effects, unless you are one of the ones who has had it on your farm and it has completely taken your crop down,” she said.
The pea crops can look good, then go down for absolutely no reason after flowering.
The bright pink or red colour inside the root easily identifies fusarium.
“Once it’s on the farm and you start spreading it around, it lives for a very long time. Watch out.”
