May 12, 2010

Air temperatures in portions of the Nebraska Panhandle were reported to have dipped into the low teens for several hours early Saturday morning, May 8. Yes, I did say May! These very low temperatures were seen at the higher elevations and in parts of the northern Panhandle, but pretty much all of the Nebraska Panhandle experienced air temperatures in the low to mid 20s.

We were fortunate that a cool spring has resulted in slow winter wheat development. Much of the wheat in the Panhandle had just recently reached the jointing stage, where the developing wheat head moves above the ground and up the elongating wheat stem. Some wheat was still in the tillering stages and not yet jointing.

Although these cold temperatures did cause some significant damage to wheat leaves, particularly where temperatures were in the teens, this is likely to result in only minor yield losses. Significant yield losses from spring freezes occur when the developing head is killed or damaged. The wheat head is more susceptible to cold temperatures than the leaves. The risk for serious damage increases the farther up the stem the head is at the time of the freeze. This is because the ground and surrounding leaf canopy have less of an insulating effect as the head moves farther up the stem.

In general, I believe most if not all of the winter wheat in the Panhandle will recover from this spring freeze event once we get some warmer days. Even if some wheat heads were killed by the freeze, it is early enough for other tillers to make up for much of this loss.

Soil moisture conditions in most of the Panhandle are very good to excellent. Although this week’s snowstorm in the western Panhandle created quite a visual effect, air temperatures did not go much below freezing and the wet snow provided insulation and excellent moisture. We just need some warmer days to allow for new growth to resume. With any luck, this will be the last spring freeze event for this year. As the winter wheat crop continuous to develop, additional spring freezes are likely to be more devastating to yield than the May 8 freeze was for most Panhandle wheat growers.

Assessing Damage

To evaluate potential losses in individual fields, randomly samples individual wheat plants to examine more closely.  Locate the growing point by splitting the stem lengthwise with a sharp knife. An uninjured wheat head is bright yellow-green and turgid, whereas an injured wheat head will become white or brown and water-soaked after a few days of warm weather.

See the May 7 CropWatch article, Assessing Winter Wheat Damage after Expected Freeze, for further details and pictures.

There has not been much warm weather since the May 8 freeze so you may want to wait until after we have a couple days in the 60s or 70s before trying to assess damage to wheat heads.

Drew Lyon
Extension Crops Specialist, Panhandle REC, Scottsbluff