|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.