Frost has taken a toll on the canola crop in Western Canada over the last few weeks. In some cases, where temperatures dropped well below -2 degrees for an extended period, the decision to reseed is easy. However, the replanting decision is more complicated in most instances.
As part of this Canola School episode, Anastasia Kubinec of Manitoba Agriculture, takes us through that process of deciding whether frost damage warrants reseeding. Ultimately, whether assessing for frost or flea beetle damage or both, the decision is based on how many plants per square foot (or square metre) are still growing.
“It does take a couple of days (after a frost) for the extent of the damage to show up. Even if it looks terrible when you look at it the day after, if you go back the next day or two days after you may see quite a bit of green tissue and that the plant is coming back,” she explains. “The thing to look for is the actual growing point of the plant, not just the cotyledons or some of the leaves that have been damaged. If the growing point is green, you’re probably in pretty good shape.”
She notes a minimum of 3 to 4 plants per square foot is recommended, but 1 to 2 plants per square foot can suffice if the canola is not at risk of other stressors, including weeds and flea beetles. If reseeding, Kubinec suggests going with a higher seeding rate (5 lbs/acre or higher) and not applying additional fertilizer — both measures should help reduce the risk of losing canola to frost in fall.
Seed availability could also factor into a grower’s decision to replant canola, as growers have reported being unable to source supplies of popular varieties.
“Most companies have been trying to move seed to the areas where the frost occurred, so there should be seed available. It just might not be the variety you want,” notes Kubinec.
The Canola Council of Canada emphasizes many of these same points in this article on reseeding decisions.
Related articles in the Canola School archives:
- Canola School: Evaluating Frost Damage (& Going Fishing)
- Canola School: Evaluating Your Frost Damage
- Canola School: Assessing Seed Survival and Seeder Performance