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Will winter wheat survive the cold?
The recent cold temperature stint and harsh winter weather has sure taken a toll on us, but how about the winter wheat?
The big question is will winter wheat be injured or survive the low temperatures between late fall and this winter? According to the University of Nebraska-Lincoln, the greatest injury occurs when the soil is dry. Dry soil warms up and cools down six times faster than moist soil. Loose seedbeds at seeding also dry out faster and hence cool down and warm up more rapidly, contributing to winter injury. With the winds and lack of precipitation in many areas, the possibility of injury is increased.
Varieties of winter wheat vary in their resistance to winter hardiness and injury. However, many varieties that do not have much tolerance to frigid temperatures were able to survive the recent winters and milder temperatures.
The crown level is an important factor when evaluating the injury and survival rate of winter wheat. For example, the temperature at the crown level and how well the crown is protected by soil is essential for survival. Winter wheat that is seeded shallowly will have a crown that is closer to the surface thus more susceptible to injury. Even crowns exposed on terraces or slopes have a greater chance at suffering from winter injury.
Winter wheat plants that have good crown root systems and two or more tillers can tolerate the cold temperatures much better than less developed plants. Also, plants that have had time to cold harden properly with a gradual decline as opposed to rapid temperature decline do better.
To determine if your winter wheat is damaged and dictate survival rate, the University of Nebraska-Lincoln has a sample test that can be done.
- Remove the top 3 inches of soil containing the plant crown (typically located 1 to 2 inches below the soil surface).
- Thaw the samples and warm to room temperature.
- Remove soil from the roots and wash with cool water to remove attached soil.
- Cut off roots below the crown and fall growth to within 1 inch above the crown.
- Rinse the crowns with cool water.
- Place 10 wet crowns in a labeled plastic bag, inflate the bag, and tie shut.
- Place the bags in a lighted room, but not in direct sunlight.
- Check the crowns in two days, rinse with cool water, and reinflate the bag.
- After four days, the crown should show about 2 inches of new growth.
- Plants that are not growing after six days should be considered dead when estimating survival.
- Some plants may grow poorly and develop molds that live on dead or injured plants.
Keep in mind, winter-kill can be a localized event, so select sample areas carefully, and don’t try to extrapolate results too widely.
Chart by UNL Extension. Source: Robert Klein, UNL Extension Western Nebraska Crops Specialist