Canola School: What to do when faced with frost


Early spring can mean risky temperatures, especially for earlier seeded crops; and if canola has emerged already, there’s a risk of frost.

If your field has had a touch of frost, the first piece of advice from Autumn Barnes, agronomy specialist with the Canola Council of Canada (CCC), is to pump the brakes.

“There were some areas that hit -3 °C, -4 °C, which can damage canola seedlings, but it’s going to take a while to be able to truly assess that damage,” says Barnes. If there are some fields that got hit hard, she suggests to watch specific areas for seedling death by flagging them with flags or washers.

Frost can cause some of the leaf tissue to desiccate, or dry off, and the stem will look pinched, says Barnes. Sometimes, the plant will push out new growth, so avoid being hasty in making a re-seed decision. (Story continues below video)

As far as a threshold for making a re-seed decision, Barnes says one to two plants per square foot will still get that crop to harvest. There’s no hard and fast number for when a re-seed decision is warranted, because the plant stand density will be different from region to region, but it’s still a good piece of data to record, and understand, come harvest.

After five to 10 days, the crop condition typically won’t get worse (barring another frost event), and a decision can be made after that timeframe. Sometimes, it may take longer for the crop to recover due to the plant having very little alive tissue, so it’s a game of patience, says Barnes.

“Another important thing with frost, is put the sprayer away for awhile,” says Barnes, because if there’s no actively growing tissue, the crop should not be sprayed.

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