Winter Wheat Condition Should Improve Soon

Writer: Tim W. McAlavy, (806) 746-6101, email: t-mcalavy@tamu.edu
Contact: Calvin Trostle, (806) 746-6101, email: c-trostle@tamu.edu

LUBBOCK – Farmers from Midland to Dimmitt have reported purple and dark reddish winter wheat, as
well as thin stands, in the past couple of weeks. But a Texas A&M agronomist says these conditions are
only temporary. The discolored plants should green up, and thin stands should improve as warmer spring
weather arrives.

“I have seen a lot of reddish and purple leaf tips, mostly on the top of older leaves that are more exposed to
the weather. If we were talking about corn or other crops, it might indicate phosphorus deficiency...which
typically discolors wheat stems, not the leaves,” said Calvin Trostle, Extension agronomist based at
Lubbock. “Phosphorus is relatively mobile within the plant, so I don’t think phosphorus is the culprit.

“My counterpart in Amarillo (Extension agronomist Brent Bean) and I believe this leaf discoloration is due
to frost and cold weather. If you turn these discolored leaves over, they are green underneath...which mostly
rules out the possibility of a virus or some other plant disease.”

Trostle and Bean feel the purple leaf discoloration will disappear as the weather warms, perhaps in a few
days or weeks. The color difference is already noticeable in some fields, they said.

The agronomists also report some producers are concerned that their wheat looks “thin.”

“A dryland seeding rate of 40 pounds per acre should result in about 15 seeds per square foot. If  two-
thirds of that seed grows into established plants, we would be see about 10 plants per square foot,” Trostle
said. “In short, a field of wheat might look thin...especially the finer-leafed varieties...and still have modest
grain yield potential. However, its forage potential may depend more on the weather.”

March and April weather typically has a big impact on forage and grain yield potential on the High Plains.
More often than not, this impact is greater than that of seeding rates and winter plant stands.  “Some of
these thin stands might need a light shot of N (nitrogen) -- especially if they look yellow -- to encourage
further tiller development,” Bean added.

Seed test weight, germination and planting depth are other factors that affect stand health and yield
potential. Texas Cooperative Extension recommends planting seed wheat with a test weight of at least 57
pounds per bushel, and germination of at least 85 percent. Shallow planting (less than 1 inch) is not
recommended even in moist years because it encourages shallow roots, Trostle said.
 
“On the other hand, with older grain drills and fluffy seed beds, too often we see wheat planted too deep --
hence slower emergence and establishment,” Trostle said.

“Overall, our soil moisture conditions look good, though we are drying out on top in some areas. We are
also seeing some leaf mortality, especially in fields where the plants are only rooted from three to five
inches deep...in the dryer topsoil layer,” he added. “Leaf mortality can be alarming, but it is typically due to
moisture and cold weather stress.

“You should expect some leaf mortality, and keep an eye on it while you monitor the newer, top growth.
The new top leaves should be healthy and vigorous.”

There are also scattered reports of large greenbug populations, but that is not the case for most of the South
Plains at this time, the agronomist said.

“TAM 11 is one of our best multi-purpose forage and grain varieties for the South Plains. It is greenbug
resistant, but that doesn’t mean it is IMMUNE to greenbugs,” Trostle concluded. “It is about average for
forage production, but it is one of our best grain varieties in the Panhandle and South Plains. We
recommend TAM 110 for irrigated and dryland production.”

County agents across the South Plains can provide producers with several invaluable publications from the
Extension’s “Wheat Book.” These include: “Wheat Jointing Identification and Grazing Pull-Off” as well as
“Growth Stages of Wheat: Identification and Understanding Improve Crop Management.”  Both are also
available on the Internet at  http://lubbock.tamu.edu/othercrops/ .