Did you have frost last night? Growers with standing canola are wondering whether to swath right away. Before making that decision, note the temperature and duration of the frost.
Heavy frost is considered anything below minus 2°C. Many parts of north central Alberta and northwestern Saskatchewan were down to minus 5°C or lower this morning and had been cold for many hours. The photo below shows canola pods that experienced a minus 7°C frost this morning. Damaged pods turn translucent quickly, and will desiccate and possibly shatter within day.
If you had a light frost… above -2 C
Hold off swathing. Check this afternoon for wilting to make sure frost damage was not heavier than expected. You may see some speckling on the stem and pods, but this is of no concern as long as the plant is still alive. If no wilting, leave the crop standing and check daily.
What to look with daily monitoring:
—If the majority of the seeds remain turgid, delay swathing to allow for further seed maturity.
—If the pods are severely damaged and are beginning to desiccate, swath during periods of dew or high humidity to reduce the amount of pod shelling and pod drop.
Why wait? The amount of frost damage depends on various factors including crop stage, degree and length of frost, relative humidity, and presence of rain or dew. In many cases, a light frost will damage the outside of pods but seeds can continue to mature — increasing yield and quality — if the crop is left standing.
Frost and quality.
If you have further questions, click the name of the Canola Council of Canada agronomist in your region and send an email.