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| I have had lots of calls and emails regarding the potential wheat freeze damage, so I wanted to share my thoughts and photos.
I am located in W.KY and we had 24F forecasted as a low this morning which many expected to be a big problem. Our wheat (here in this immediate area) is around Feekes growth stage 8 (flag leaf emerging), so it would have been susceptible to such temperatures. However, these are my observations this morning, based upon using 4 digital thermometers that record low temperatures.
1) The low temperature recorded here by one of the digital thermometers at 4' (four feet) above the ground was 26.1F. (this is important becuase most weather recording stations record temperatures at 4 or 5' above the ground) The temperature only dropped below 28F between +/- 5 & 6am, so the time below 28F was less than an hour... (This is important too)
2) The low temperature recorded within the wheat field 4" (four inches) above the ground in a tramline was 33.6F
3) The low temperature recorded within a thick area of the field 4" above the ground was 32.7F (not sure why it was slightly lower than the exposed tramline)
4) It was partly cloudy this morning at daybreak and the wind was blowing 10-12mph from the NW. (cloud cover may have held the temperatures higher than forecasted and reduce the leaf burn, but I am not sure of the impact of the wind)
As a result of these low temperatures within the canopy, I would expect little to no injury HERE from this mornings freeze. I did see some leaves that were burnt however, but these were resricted to areas of the end rows which had N doubled up and the plants were more lush as a result.
Now for the guys in OK/KS who recorded 20-22F lows this morning (on wheat from stages Feekes 6-8), you will have to extrapolate my thoughts and numbers above, regarding canopy temperatures. If the grain heads recieved less than around 25-26F temperatures for more than a couple of hours, I am expecting you may have some head damage and possibly stem damage. Two topics that may help your wheat in those areas are 1) heat rising up from the soil may help provide a barrier to reduce freeze injury and 2) many producers across the central plains have wheat thats too thick, and even if the main stem gets frosted, the tillers will take over to create yield potential. (You have the moisture to help this happen).
Just a few ideas. I welcome any other thoughts or experiences.
Phil Needham
Wheat Management Consultant
www.needhamag.com
 (Thermometer in tramline April 7th 2007.jpg)
 (Thermometer in thick wheat April 7th 2007.jpg)
 (Burnt leaf tips.jpg)
Attachments
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 Thermometer in tramline April 7th 2007.jpg (96KB - 250 downloads)
Thermometer in thick wheat April 7th 2007.jpg (92KB - 240 downloads)
Burnt leaf tips.jpg (89KB - 249 downloads)
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Freeze Damage On Wheat? (Thoughts and Pics)
