Canola School: Frost events and when to assess damage

Frost can be highly variable and the damage it does all depends on how cold it gets, how long it stays cold, and how far it penetrates the crop canopy. If you do get some frost, it’s generally recommended to assess your canola crop, to see what’s happening in your own fields, but to be patient when making decisions.

“We want to get out and assess our crop, today,” says Angela Brackenreed, agronomy specialist with Canola Council of Canada. “Take a look at the pods and just see if you’re noticing any impact of that frost, four to six hours after it occurred, but really we shouldn’t be making any decisions today.”

Brackenreed suggests waiting a few days to see the full effect the frost had (or hopefully didn’t have) on pod integrity.

If the canola is immature and seed moisture is higher than about 20 per cent, then the frost will lock green into the seed, creating a quality issue. If the frost impacts immature green pods, it will rapidly desiccate them and split them, causing a yield loss issue. (Story continues below video)

Frost damage might not be much of an issue if your crop is past the point of being vulnerable, says Brackenreed, but there are some acres out there that were seeded later, that may be vulnerable.

Swathing ahead of a frost is one option in the face of an impending frost, but it can be risky to swath your standing canola too early in the hopes of protecting it from frost. The crop needs at least three days for moisture to drop down before a predicted frost event to offer protection. If the frost event doesn’t occur, you’ve potentially sacrificed some yield.

If you’re still planning to straight-cut your canola and intend to apply a pre-harvest aid, such as glyphosate, remember that it won’t work as effectively if the plant’s been affected by frost, or if the daytime temperatures are cool or conditions are cloudy.

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