Freezing Temperatures May Have Damage Winter Wheat at Advanced Growth Stages in KY

Carrie Knott, Extension Agronomist-Princeton, University of Kentucky

Tuesday night temperatures dipped to or below 24°F for several hours at many locations throughout Kentucky. For winter wheat that has reached the jointing (Feekes 6) growth stage, or beyond, damage can occur to the developing wheat head at these temperatures.

In general, we think that injury can occur if temperatures are at or below those listed in the table below for 2 or more hours.

Some areas across the state already had wheat that was beginning to head. This will make scouting field for freeze damage very important.

To assess wheat freeze damage:

1. Wait until high temperatures are at least 40°F for 5 to 7 days. According to the projected weather forecast, we will have high temperatures greater than 40°F all week, therefore assessing freeze damage Monday or Tuesday will likely provide an good estimate of freeze damage.

2. Scout fields

A. For fields that have not yet headed and look for yellow, chlorotic growing points and    limp leaves. There will likely be yellow leaf tips, but as long as the growing point is not affected, there will likely be minimal to no damage.

B. For fields that are in the ‘Boot’ (Feekes 10) growth stage, dissect out the heads and look for damage.

C. For field that have headed or beyond, inspect heads and florets for damage.

3. An additional concern for wheat stands and yield potential is heaving.  If extreme temperature changes occur the freezing and thawing cycle may push wheat plants out of the soil.  This will result in reduced stands and could ultimately affect yield if heaving occurs on a large percentage of the field.