Grain growers advised about powdery mildew

By MINDY POEHL | Central Texas Edition

Dr. Gaylon Morgan displays grains and speaks about protecting them from diseases. Photo by Mindy Poehl

May 27, 2004 -- Wheat crops across Central Texas have the potential to produce high yields, if they are protected from diseases. Powdery mildew and leaf rust can reduce the yield, seed quality and bushel weight.

On Friday, May 14, at the McGregor Experiment Station, Dr. Gaylon Morgan, a wheat specialist with the Cooperative Extension Service spoke about small grains.

Texas exports 70 percent of its wheat, so it needs to be protected from diseases. Hard wheats are more susceptible to diseases than soft wheats are, Morgan said.

Excess nitrogen in the soil causes powdery mildew and leaf rust. To minimize the diseases from infecting the crops growers are advised to reduce the application of nitrogen in the fall. Powdery mildew can begin its life cycle in 100 percent humidity and in temperatures between 50 and 75 degrees, Morgan explained. Last year was a bad year for powdery mildew affecting wheat in Central Texas. Stripe rust has not been a big problem this year, but it was a big problem last year.

Fungicides will suppress most diseases five weeks after they are applied. Reducing planting rates from 100 pounds per acre to below 90 pounds per acre will open the plant canopy, allowing air and sunlight to reach the crops.

Pests also affect small grains and are active at different times during the growing season. Wheat curl mites transmit the barley yellow dwarf virus to the grains and causes them to turn yellow and die. Aphids tend to affect oats more than they affect wheats, but the Hessian fly affects wheats and is not a problem on oats.

Fields should be inspected twice a week during critical periods to make informed management decisions about pests. Tillage is an important aspect of pest control that not only destroys host plants, but also may bury some insects too deeply for survival. Reducing small grain stubble and controlling volunteer plants and summer weeds will help manage the Hessian fly and wheat curl mites.

Coronado is one of the most popular varieties of wheat in Central Texas. Morgan suggests picking three or four varieties that you think will withstand diseases and pests, and see how they work out.