Blackleg — Underestimated, Misdiagnosed and a Serious Threat to Canola


When it comes to diseases that rob canola yields, blackleg often doesn’t get the credit it deserves.

Many farmers underestimate the significance of blackleg, says Bruce McKinnon, an agronomist with Dekalb in Alberta, in the video below.

“Blackleg is a powerful disease that seems to be able to adapt to whatever we throw at it. As we’ve tightened canola rotations we’ve allowed that to develop. Blackleg has started to come back,” he says. “We’ve been a little complacent because we thought we had the resistance built in and that we had the strains covered. That’s not the case, as it’s starting to break down.”

While breeders continue to work on new sources of resistance, McKinnon says a crop rotation with cereals or corn is the best management tool for blackleg in canola.

Assessing stems for blackleg.
Assessing stems for blackleg.

“There’s not an endless pool of resistance out there,” he says. “Guys are going to have to help out with management through rotations.”

Part of the problem is that blackleg is sometimes misdiagnosed, notes McKinnon.

“I think sometimes we mistake it for sclerotinia until we actually get out there. The proper way to diagnose it is at swathing time, take your garden snips with you. Cut the plant at the base, if it’s white then you’re good to go. If you see some black lesions, then you have some infection,” he explains. “A lot of times growers are very busy and don’t take the time to do that.”

Related: Canola School: I’ve Found Blackleg in my Canola Stubble — Now What?

McKinnon spoke with Shaun Haney at one of the stops on the Monsanto Momentum Tour at Carseland, Alberta:

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