May 16, 2012

Frost: Did the crop survive?

It can take a few days after a frost before you can accurately answer that question. With a light frost of 0 C to -2 C, the risk of crop damage is minimal. With a heavy frost that kills off the cotyledons, it takes a few days before new leaves will start emerging from the growing point between the cotyledons. If no growth occurs within this time, the plant is likely dead. Also, if the stem is pinched off or the plant flops over, the plant will likely die. The pinched off or broken stem cannot provide nutrients to the growing point.

Check the whole crop the day after a frost and 3-4 days after a frost to assess the situation. Click here and here for tips on how to check the field.

Early season frost can thin a stand, but in most cases a sufficient number of canola seedlings will survive. Most often reseeding a frosted field will fail to improve returns.

Both of these were hit by frost. The one on the left with the pinched stem, typical of heavy frost damage, may not survive — although it does seem to be showing green regrowth. Give it a couple days then check again.
Heavy frost damage tends to pinch off the stem near the growing point. This seedling will likely die.Source: Murray Hartman
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