Evaluating freeze damage in wheat
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EmailHow the recent cold temperatures may have affected your wheat.
The unseasonably warm weather we experienced the week of April 10, 2023, moved physiological development in wheat forward considerably. Much of our wheat crop moved out of the tillering stage and into pseudo-erect stems—the precursor to stem elongation. The next week (April 17) was followed by near or just below freezing temperatures.
Yield impacts from freeze damage are highly dependent on wheat growth stage. Up to Feekes 6, the growing point is below the soil surface in wheat seeded at proper depths. Even with very low air temperatures, the soil protects the growing point from damage.
It is true that soil temperatures have decreased over the past two weeks, but they’re not even close to freezing.
At Feekes 6, the developing head is located at the top of the first node visible above the soil surface. As the plant elongates to two, three and four nodes (Feekes 7, 8 and 9), the head is pushed farther from the soil surface, making it more vulnerable to frost.
When assessing wheat stands, make sure you check your growth stage. If you are at Feekes 6 or later, dissect the main stem and locate the head.
If you can find ice surrounding the head, you may have cause for concern. It may take a week to 10 days for wheat to come out of frost damage. Go back then and dissect more plants and assess the heads. This will give you a better idea how much damage has been done.
For more on scouting your wheat field for frost injury, watch Michigan State University Extension’s 4:30 minute video "How to Assess Wheat Fields for Frost Injury" on the Michigan Wheat YouTube channel.
Frost damage during stem elongation and reproductive stages generally occurs in more southern climates. This is where the most yield damage occurs.
Typically in Michigan, once we reach Feekes 6 and the plants are more sensitive to freeze, we are beyond our hard frosts. You may see some tip burn on leaves from freeze damage, but it is mostly cosmetic and will not hurt yields. Varietal response to freeze is also variable.
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Table 1. Temperatures that cause freeze injury to wheat at spring growth stages and symptoms and yield effect of spring freeze injury. Source: Spring Freeze Injury to Kansas Wheat, KSU Extension Bulletin C-646. |
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|---|---|---|---|
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Growth stage |
Approximate |
Primary symptoms |
Yield effect |
|
Tillering |
12 F (-11 C) |
Leaf chlorosis; burning of leaf tips; silage odor; blue cast to fields |
Slight to moderate |
|
Jointing |
24 F (-4 C) |
Death of growing point; leaf yellowing or burning; lesions, splitting, or bending of lower stem; odor |
Moderate to severe |
|
Boot |
28 F (-2 C) |
Floret sterility; spike trapped in boot; damage to lower stem; leaf discoloration; odor |
Moderate to severe |
|
Heading |
30 F (-1 C) |
Floret sterility; white awns or white spikes; damage to lower stem; leaf discoloration |
Severe |
|
Flowering |
30 F (-1 C) |
Floret sterility; white awns or white spikes; damage to lower stem; leaf discoloration |
Severe |
|
Milk |
28 F (-2 C) |
White awns or white spikes; damage to lower stems; leaf discoloration; shrunken, roughened, or discolored kernels |
Moderate to severe |
|
Dough |
28 F (-2 C) |
Shriveled, discolored kernels; poor germination |
Slight to moderate |
To find out more about temperatures and to look up weather data for your area, please visit MSU Enviroweather. There you can find your nearest weather station and run reports on temperature, rainfall, soil temperatures and more.
If you have any questions, contact Dennis Pennington at pennin34@msu.edu or 269-832-0497. Or visit the MSU Extension Wheat website.
