How did the recent cold snap affect my spring cereals?
Much of the province experienced chilly overnight temperatures over the weekend. Some farmers have begun seeding, so it’s important to remember how cool temperatures affect spring cereal crops. To see how the cool weather over the weekend affected soil temperatures, see the Manitoba Agriculature 14-Day Regional Soil Temperature Histories.
In general, spring cereals are very tolerant to cold temperatures (as low as -6°C), as the growing point of the seedling is still below the soil surface until the 5-leaf stage. If the frost is short (less than 2 hours) and light (-1°C to -2°C), damage may be minimal. Risk increases as the temperature decreases (below -2°C) and length increases (over 2 hours). Other environmental factors that influence frost damage include:
- Cloudy and wet weather: cool temperatures slow plant growth and “harden” plants off, aiding in frost tolerance. Wet soils act as a “buffer” to cold air, as they change temperature slower than dry soils.
- Sunny and dry weather: highest amount of frost damage is typically observed when plants are actively growing, and a dramatic temperature drop is followed by warm and sunny weather.
If you suspect your crop may have been damaged by the frost, look for dark green, discolored leaves with some dead tissue at the leaf tip. Damage should be visible 1-2 days after the frost. However, new leaf growth from the growing point should be observed within 2-3 days.
For newly emerged seedlings, look at the colour of the radicle (first root) and coleptile (first shoot). If both are white and firm, the sprout was likely not damaged. Additionally, seedlings can be dug up, placed between moist paper towels and kept at room temperature. If sprouts appear within 24 hours, the seed is viable.
If you find that many plants did not survive the frost, the next step is determining your plant populations. If your stand has been reduced from the target (28-33 plants/ft2), to 10-12 plants/ft2, you’ll likely want to investigate re-seeding options. If your stand is between 20-27 plants/ft2, you can expect 85-95% yield potential.
Article written by Mallorie Lewarne, MWBGA Agronomy Extension Specialist.
Information in this article was sourced from:
CropChatter article “Effect of Spring Frost on Emerging Crops” originally posted May 8th, 2015.
The Growing Point article “Assessing cereal frost damage” originally posted May 28th, 2019.