Since my post on Saturday morning, we had two more frosts here in W.KY, the worst one was on Sunday morning (April 8th), when I recorded the temperature dropping all the way down to 14.2F at a height of 4' above the soil. The temperature at the soil surface only dropped down to 23.2F, but that was enough here to cause injury to some wheat fields.

The worst injury symptoms in this area appear in early planted, early maturity varieties and elevated fertility fields (especially high fall N rates or early spring single N applications). A combination of the factors previously listed compound the injury levels, especially wheat fields were no-tilled. I am suggesting that no-tilled fields had a lower level of heat radiating up from the soil surface, (compared to conventionally tilled fields) which allowed the frost to have a greater impact on the wheat heads and stems. Lower regions of rolling fields also sustained more injury than elevated areas.

For those of you in other areas of the country that had wheat fields that reached or exceeded the jointing stage AND received similar freezing temperatures, I strongly suggest you look at your fields to determine IF you have injury. For those of you in the central plains, some of you are already reporting regions of wheat falling over as a result of stem injury. I am suggesting more of this will occur within fields (with the above listed variables) over the next few days as temperatures warm up.

Regarding tearing up fields, that is a field by field decision. Be aware that some fields may be damaged and others have NO injury. Take your time and accurately access each field. (It may be a few more days before you can make the appropriate decision, depending on the temperatures)

Determining Damage 

There are a number of areas on the plants to look for damage, but these primarily include the developing grain head and the stem. Healthy fields have strong, green stems with a springy green wheat head that contains a green vein up the center.

Damaged fields have any or all of the following: crimped, pinched, weakened, pale or watery stems, white, limp and wet looking grain heads. (SEE PHOTOS)


Phil Needham

www.needhamag.com

(14F Sunday April 8th 2007 LR.jpg)

(Healthy Wheat Head LR.jpg)

(Unhealthy Wheat Plant LR.jpg)

14F Sunday April 8th 2007 LR.jpg (95KB - 711 downloads)

Healthy Wheat Head LR.jpg (94KB - 765 downloads)

Unhealthy Wheat Plant LR.jpg (90KB - 879 downloads)