spring frost

Monday, May 01, 2017

Generally, crops will withstand varying degrees of frost. Wheat, barley, corn and oats are better at withstanding frost because, up to the 5-6 leaf stage, their growing points are located below the ground where they are protected. Peas also exhibit this growth characteristic and are relatively frost tolerant. Crops with growing points above the ground such as canola, flax or field beans are most susceptible to frost damage. The chart below provides a general indication of temperatures that may cause visible frost damage. 

Spring wheat -5.5 to -3.9
Oats -4.4 to -3.3
Barley -3.9 to -2.8
Canola -9.0 to -3.0
Beans -1.0 to 0.0
Sunflower -5.5 to -3.9
Flax -4.4 to -3.3
Soybeans -1.0 to 0.0
Corn -1.0 to 0.0
Potato -1.0
Buckwheat 0.0

Environmental conditions before or after a low temperature influences the extent of crop injury. If the decrease in temperature is gradual, plants are in better condition to resist injury and can withstand surprisingly low temperatures.

For cereals, damage may occur at the higher ranges; however, this damage would not likely result in crop death. For unhardened canola, temperatures of less than -3ºC could potentially kill the growing point. If canola has been hardened (subjected to cooler temperatures for a number of days prior to the frost event), it can potentially tolerate -9ºC before damage occurs.

The number of hours of continuous frost can also affect the extent of damage.