Assessing Winter Wheat Freeze Damage

Carrie Knott, Extension Agronomist-Princeton, University of Kentucky

Last night temperatures dipped below 24°F for several hours throughout Kentucky. Winter wheat at the jointing (Feekes 6) growth stage, was likely damaged by these cold temperatures.

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, most of the state will have high temperatures greater than 40°F the next 7 days. Assess freeze damage next Tuesday or Wednesday. Any earlier than the middle of next week may provide an inaccurate estimate of damage.

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

Figure 1. Wheat heads showing freeze
damage at heading (Feekes 10.5)

Carrie Knott, Extension Agronomist-Princeton, University of Kentucky

Last night temperatures dipped to or below 24°F for several hours at many locations throughout Kentucky (Table 1). For winter wheat that has reached the jointing (Feekes 6) growth stage, damage (Figure 1) can occur to the developing wheat head, which is above the soil surface at jointing, when temperatures are 24°F or below for at least 2 hours.

2016 UNIVERSITY OF KENTUCKY WHEAT FIELD DAY

Colette Laurent, UK Grain Crops Coordinator

The annual UK WHEAT FIELD DAY is slated for Tuesday May 10, 2016 at the UK Research and Education Center in Princeton, KY.
Registration will begin at 8:00 am (CDT).  The tours will end at noon and field day will conclude with a lunch sponsored by the Kentucky Small Grain Growers Association.


Field Day Topics Include:

Potential for Winter Wheat Freeze Injury

Wheat Head Freeze Damage, 2015. 
A freeze event (24°F or less for more than 2 hours)
occurred at Feekes 6 (jointing).

Carrie Knott, Extension Agronomist-Princeton, University of Kentucky

Much of Kentucky’s winter wheat crop is still tillering (Feekes 4-5; Figure 1) or just beginning to joint (Feekes 6; Figures 2 and 3). The weather forecast for this weekend is predicting that some areas of Kentucky will dip to 32°F or less. Given that most of our wheat is at Feekes 4 or 5, with some at Feekes 6, these temperatures are not cause for concern.  

Temperatures must be 12°F or less for 2 or more hours to injure wheat that is at the Feekes 4 or 5 growth stages, which much of our state is now.  For the more advanced wheat that is jointing, Feekes 6, temperatures must fall to 24°F or less for 2 or more hours.  Although the weather forecasts do not project conditions that we would expect wheat injury, examine weather data and scout your fields to determine is freeze injury occurred. 

Freeze injury can occur in small areas of fields, which are associated to low areas of fields where cold air settles.  Be sure and check for wheat stems damage close to the soil surface; characteristic symptoms of freeze damage are listed in Table 1.  It typically takes about 10 days of warm temperatures before injury can be seen.  Weather data can be accessed by clicking on the link of your county at wwwagwx.ca.uky.edu or www.kymesonet.org. 

Figure 1. Wheat field at Feekes 4 growth stage 

Figure 2. Wheat at Feekes 6 growth stage.
"Joints" are indicated with orange arrows.

Figure 3. Wheat at late Feekes 5/early Feekes 6 growth stage.
The "joint" (growing point; around the 1-3/8" mark) is right at
or slightly above the soil surface.  This 'joint' is visible
after the top few leaf sheaths were removed.