Canola School: Scouting and spraying for sclerotinia

We’re starting to see some flowering in canola and with that, scouting for sclerotinia is on the to-do list. Justine Cornelsen, with the Canola Council of Canada, based out of Manitoba, joined Kara Oosterhuis in this latest episode of Canola School.

“It comes down to environmental conditions,” says Cornelsen, “Do you have enough moisture? Is that canopy wet? Is the soil saturated?” Those sclerotia bodies— or inoculum—are just waiting for the perfect conditions to germinate and produce spores.

In addition to having enough moisture to germinate, sclerotinia favours hot and humid conditions for growth. First, look for golf tee-like mushroom bodies, called apothecia, explains Cornelsen.

They’re tough to find—a get down on your hands and knees type of situation. Spores from these apothecia will get pushed up onto leaves of the plant. Then, the flower petals, the food source for the disease, will drop down through the canopy and that’s when the infection really starts. Wherever the petal lands can result in an infection point and it’ll look like watery lesions on the stem and eventually even grey mould and sclerotinia stem rot.

Fungicide should be applied by coating as many petals as possible — anywhere from 20 to 50 per cent bloom. Thirty per cent bloom is the average recommendation from the Canola Council of Canada, because that’s when petals start to drop. It’s important to push the water volume lower into the canopy as well, because that’s where the infection occurs.

Producers now have the option to grow a sclerotinia tolerant varieties that perform better than other varieties, but in a high pressure year, a fungicide application is still recommended. There are also new tools, like DNA testing for spores, that can help make the decision of whether or not to spray.

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