James Herbek and Chad Lee, University of Kentucky
April 2004

The relatively warm fall caused much of the wheat in Kentucky to grow faster than expected. The fluctuation of freezing and warm temperatures this spring has caused some damage to wheat. The symptoms from cold temperature damage to wheat appear as leaf burn, where the leaf blades appear yellow to reddish brown at the leaf edges. The reddish brown fades into yellow closer to the leaf mid-rib. The leaf burn often occurs on the upper portion of the leaves. Stem damage can occur from cold temperatures. The stems will be weak at the point of damage and may bend or break. Often the wheat will compensate for the damaged stalk and return to an upright position. However, the wheat may be more likely to lodge at later growth stages.

Wheat yield losses from cold temperatures depend on the wheat growth stage, temperature and duration of temperature. Table 1 includes the conditions required for freeze injury to wheat as well as the expected impact on yield, while Table 2 describes each growth stage of wheat. Table 1 is a copy of Table 3-3 from ID-125: A Comprehensive Guide to Wheat Management in Kentucky and Table 2 is a copy of Table 2-1 from the same publication.

The vague yield effects in Table 1 indicate that predicting yield from wheat injured by freezing temperatures is not an exact science. In addition to wheat growth stage and temperatures, yield losses depend on the weather conditions following freeze injury. Cool, damp conditions will slow recovery from the freeze injury, while warmer conditions will accelerate recovery.

One factor that will help to determine the severity of damage to wheat is the condition of the developing wheat head. A healthy developing wheat head is light green in color, glossy and turgid. A damaged head will be pale white to tan with a limp appearance. To help determine potential yield impacts, investigate the quality of several developing heads in the field. If most of the wheat heads are damaged, then expect moderate to severe yield losses. If very few of the wheat heads are damaged, then expect slight to moderate yield losses.

For questions about freeze damage to wheat, contact your county extension office.  

^a Numbers in parentheses refer to the Feeke's scale (see Table 2.)

Wheat Growth Stages Identified by the Feekes Scale