Manitoba Agriculture says sclerotinia was the top disease in last year's provincial canola disease survey.

Plant Pathologist Holly Derksen notes that between 90 and 100 per cent of the fields in every region had some level of sclerotinia, with about 15 per cent of plants in diseased fields having instances of the disease.

She says the weather in 2016 created the perfect conditions for sclerotinia.

"This year with our high levels of moisture, and if you had a decent crop canopy, it was just the perfect storm for sclerotinia," explained Derksen. "The cooler temperatures actually lengthens the flowering process of canola and that's when sclerotinia can affect."

Derksen estimates yield losses to be about 10 per cent in affected fields.

She adds yield loss could have been a lot worse if farmers did not spray for the disease.