Canola School: New online tools support blackleg management


The Canola Council of Canada (CCC) has recently updated a few agronomy graphics, including the life cycle of blackleg.

“We’ve had different life cycles in the past, but we wanted to update it and provide a little bit more information kind of in a one shot,” says Justine Cornelsen, agronomy specialist with CCC.

In this Canola School episode, Cornelsen talks about how blackleg affects canola, and how the graphic explains the critical window for scouting for blackleg.

“Through some of our recent research, we’ve really dialled into that cotyledon to two-leaf stage,” says Cornelsen. “If you can protect your canola plants at that stage from a blackleg infection, you shouldn’t have to worry about any sort of yield loss; you’re really going to reduce that pressure.”

The main way of protecting the crop from early season blackleg infection is through genetics — an effective major gene will stop the pathogen from entering the plant at this stage, says Cornelsen.

If the major gene of the variety is not effective against blackleg, then you start to rely on quantitative resistance, says Cornelsen, which will slow an infection, but not completely prevent against yield loss. Systemic seed treatments, which is taken up by the plant, will protect until about the one-leaf stage.

“Lastly, and this is one of our older recommendations, is a foliar fungicide application,” says Cornelsen, which needs to happen extremely early for it to pay off by harvest.

Catch the full interview between Cornelsen and RealAg field editor Kara Oosterhuis, story continues below video:

Another great tool that CCC has unveiled this year is a yield-loss calculator, that Cornelsen says is another exciting component coming out of Canadian Agricultural Partnership research funding, based on updated work from the University of Alberta. The original work for the yield-loss models, was about five years ago.

“We don’t see much loss at really low disease severity ratings, so if we’re only getting a rating of one on our zero to five scale, we don’t see any yield losses there,” says Cornelsen. “It’s when you have disease severity ratings for blackleg over that one, where you start to see yield loss.”

Cornelsen says that lots of farmers and agronomists did a great job of scouting last harvest, but have a tough time comparing between blackleg, sclerotinia, fusarium wilt, or a new disease, verticillium stripe.

Blackleg seems to be the silent yield-robber in canola, says Cornelsen and “it doesn’t take a lot of pressure to take away that yield.” It’s a stubble-borne and air-borne disease, so growers need to allow time between canola crops for the disease pressure to subside.

CCC hopes that by providing updated information in a graphic, growers will be able to better identify the disease, and, in combination with the yield-loss calculator, realize the damage it causes.

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