Frosted pods shattering

Sept. 21, 2010 — Swath canola hit by heavy frost. Canola that was still fairly green when heavy frost hit this week will desiccate quickly. Pods can start dropping or shattering within days. The photos below show canola pods 24 hours after a minus 7°C frost this week. Pods dry out prematurely, then shatter or break off at the pedicel.

In areas hit by successive heavy frosts, growers planning to straight combine should reconsider that decision unless the crop had dried down naturally prior to the frost. If pods were already leathery, the frost may have little effect on shattering risk. But frost damage to green crop will leave those pods in jeopardy of both shattering and pod drop. Waiting to straight cut green crop hit by heavy frost may mean considerable losses.

Green crop hit by heavy frost should be swathed, and probably right away. Immature, watery seed will see little if any advantage from waiting. With frost damage, this seed probably won’t finish filling even if the crop is left standing. For seed near maturity, frost has locked in chlorophyll and it likely won’t clear. Look for seeds that are brown on the outside but dark green inside. Mature seed is ready.

The exception… Southern Alberta and parts of eastern Saskatchewan

These regions had a late start to the year, with a lot of canola seeded in June. Late-seeded fields have only been in the ground three months. The crop is still green but is actually progressing at a normal pace. Don’t be in a rush to swath this canola, especially if you haven’t had a killing frost of below minus 2°C. If you get a couple weeks of warmer weather without a heavy frost, this canola could mature nicely. Swathing now would cut off this potential. It may be better to hold off and watch the weather forecast.


This was taken 4 hours after a minus 7°C frost in northeast Alberta late last week. Green pods are already turning white and popping open.
24 hours after the minus 7°C frost, pods are brittle and seeds are dropping. This crop should be swathed immediately. 

Within a day after the frost, pedicels — the small stems attaching pods to stems — are drying out and snapping. These pods will start dropping, which is another reason to swath right away.


If you have further questions, click the name of the Canola Council of Canada agronomist in your region and send an email.

Derwyn Hammond, Manitoba
Jim Bessel, North Central and North Eastern Saskatchewan
Tiffany Martinka, Eastern Saskatchewan
Clint Jurke, Western Saskatchewan
Troy Prosofsky, Southern Alberta
Doug Moisey, North East and East Central Alberta
John Mayko, West Central Alberta
Erin Brock, Peace Region