Freezes and Winter Wheat

Freezes and Winter Wheat

Below is the growth stages and low temperatures and low temperature durations as well as the symptoms that affect winter wheat. These came from both K-State and Texas A&M

Growth         Injurious Temperatures                                                                      

Stage              (two hours)                                   Symptoms                             Primary Yield Effects

Tillering         12 F (-11 C)          Leaf chlorosis; burning of leaf tips; silage odor; blue cast to fields Slight to moderate

Jointing             24F (-4 C)         Death of growing point; leaf yellowing or burning; lesions, Moderate to severe  splitting, or bending of lower stem; odor

Boot                  28 F (-2 C)        Floret sterility; spike trapped in boot; damage to lower stem; leaf Moderate to severe discoloration; odor

Heading            30 F (-1 C)         Floret sterility; white awns or white heads; damage to lower Severe stem; leaf discoloration

Flowering          32 F (0 C)          Floret sterility; white awns or white heads; damage to lower Severe stem; leaf discoloration

Milk                   28 F (-2 C)        White awns or white heads; damage to lower stems; leaf Moderate to severe discoloration; shrunken; roughened, or discolored kernels

Dough                28 F (-2 C)         Shriveled, discolored kernels; poor germination Slight

to moderate

The articles (data) goes on to say that a slightly higher temperature but a longer duration could have similar affects. Other factors would be environmental conditions ( such as moisture). There are a lot of variables………….

As you can see the temperature would need to get to 24 degrees for a duration of 2 hours at the jointing stage to damage the wheat. The jointing stage is where I think the majority of our wheat is at this time.

For the most part we will not be able to access the damage (if any) immediately as it will not show up for approximately 5 to ten days.

Tonight and tomorrow mornings temperatures could be critical, as well as tomorrow night and morning, but I remain optimistic at the moment. We usually lose our wheat crop at least 7 times before we get it harvested every year. This is just one of them. And as we have seen in recent years, the weather environment at the time of heading and filling (cool and moist) can heal a lot of damage.

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