Think sclerotinia won't show up just because it's been dry? Last year proved that even after a string of droughts, one wet window is all this sneaky disease needs to make a comeback. After several years of drought, many Prairie canola growers were caught off guard by sclerotinia in 2024.
“Last year… was the first year of moisture for a lot of areas after a lot of years of drought,” says Lori Yarnell, technical marketing manager with BASF, in this episode of RealAgriculture's Canola School. “What we learned is yes, [sclerotia] were there. They were there, indeed,” especially in parts of Manitoba and northeast Saskatchewan.
Even when July turned dry, a wet June was enough to create ideal infection conditions in the canopy, explains Yarnell. The timing of soil moisture, particularly in the two weeks before flowering, is critical. Prolonged moisture during that period allows sclerotia to germinate, form apothecia, and release spores.
Yarnell also reminds growers that early planning matters. Ideal plant density (five to seven plants per square foot) helps avoid overly tight canopies that hold in humidity. Once infection is visible, it's too late to act, she says.
“Unfortunately, the conditions where your yield potential looks really good…that’s also the conditions that you’re generally going to see disease,” says Yarnell.
Bottom line: if conditions are wet before flowering, consider a fungicide. Yield protection depends on it, even when the risk seems low.
