Louisiana Wheat: Will The Crop Take A Hit From Extreme Cold Weather?

Over the past several days Louisiana wheat fields were exposed to below freezing temperatures for several hours. Freezing temperatures are projected to continue through the end of the week (ending January 6). In some areas, temperatures were in the upper teens.

Fortunately, wheat was in the early growth stages prior to jointing which makes it tolerant to below freezing temperatures for several hours (Table 1). Producers will probably notice leaf injury  but this is superficial and the plants should grow out of this injury (Figures 1-4).

In the event we experience below freezing temperatures later this growing season , table 1 contains information on the impact of specific temperatures occurring for approximately two hours on injury and wheat yield.

Most oat varieties are somewhat less tolerant of cold weather than wheat and there is substantial variation among oat varieties for degree of cold tolerance.  Oat varieties sustained more leaf injury than wheat in general.

However, the oat varieties are also still in juvenile growth stages with growing points below the soil surface and therefore protected.  Where leaves were significantly damaged by cold the plants should survive and regrow with no significant impact on yield.

For more information on freezing temperatures on wheat and oats contact your local county agent or specialist.

Table 1 is taken from Kansas State publication C-646 http://fieldcrop.msu.edu/uploads/files/Knsas%20freeze.pdf

Table 1. Injury Symptoms of Wheat Resulting from Freezing Temperatures

Growth Stage Approximate injurious temps (2 hours)  

Primary Symptoms

 

Yield Effect

Tillering 12 F (-11 C)/ Leaf chlorosis; burning of leaf tips; silage odor; blue cast to field 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; head trapped in boot;
damage to lower stem; leaf discoloration;
odor
Moderate to severe
Heading 30 F (-1 C) Floret sterility; white awns or white heads;
damage to lower stems; leaf discoloration
Severe
Flowering 30 F (-1 C) Floret sterility; white awns or white heads;
damage to lower stems; leaf discoloration
Severe
Milk 28 F (-2 C) White awns or white heads; damage to lower stems; leaf discoloration;
shrunkened, roughened, or discolored kernals
Moderate to severe
Dough 28 F (-2 C) Shriveled, discolored kernels; poor germination Slight to moderate

 

Figure 1. Tip burn on wheat seven days after below freezing temperatures (about 20 F).

 

Figure 2. Tip burn on wheat seven days after below freezing temperature (about 20 F)

 

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Figure 3. Freeze injury (silvery colored streaks) on wheat seven days after below freezing temperatures.

 

Figure 4. Freeze injury (silvery colored streaks) on wheat seven days after below freezing temperatures.

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