Frost risk rising. Should I cut that green canola?

September 11, 2019 - Issue 24

A lot of canola crops across Western Canada need a couple of weeks before all seeds are physiologically mature. With the frost risk rising with each passing day, farmers wonder if they should hurry up and cut that crop – even if cutting it green means a big sacrifice of yield.

That might not be the best plan. Swathing too early in anticipation of a frost is rarely a good move. To be effective, it has to be done three good curing days ahead of the frost. This can backfire because you’re accepting a yield loss in anticipation of a heavy frost that may not occur. Read the ‘managing fall frost events‘ section of the current Canola Harvest Guide. Read ‘Frost hits canola. What to do?’

Why would a farmer cut canola early? Maybe the farmer has a lot of acres to harvest and, with the calendar flipping to September, wants to get things moving. If farmers really want to (or have to) swath some fields early, we’d recommend they start with fields where more of the seeds in side branches are firm and where overall field maturity is relatively even. Fields that are uneven (with a lot of mushy seeds in side branches) would be best left to mature a little more – especially if the canola has a pod-shatter tolerance trait.

Does early swathing mean early combining? Swathed canola can be ready to combine earlier than standing canola, but this is contingent on conditions. For instance, the current wet conditions in many regions will likely mean that mature canola left standing will dry down faster than canola in a swath. Also, canola swathed green takes a lot longer to cure than canola swathed at 60% seed colour change, and by cutting early, the crop is unlikely to meet its full yield potential. For canola left standing for straight combining, desiccants (diquat/Reglone) will not speed-up seed maturity, but they can speed up crop dry-down and make it possible to get into the field sooner. Note the important distinction: There is a big difference between maturity and dry-down. Desiccants shut down the plant and basically STOP it from maturing, which can lock in high green seed levels and end the finishing opportunity for latest seeds if applied prematurely. This article has tips for pre-harvest aids.

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