Wednesday, March 13, 2013

Field Scouting Report for March 13: Powdery Mildew, Bird Cherry Oat Aphids and Henbit Are Main Concerns in Area Wheat Fields Based on Weekly MU Extension Field Scouting

Contact: Jill Scheidt, agronomy specialist
Tel: (417) 682-3579

According to Jill Scheidt, agronomy specialist with the Barton County Extension, powdery mildew is being seen on the lower tillers in area wheat.

“Powdery mildew begins as light green to yellow flecks on the leaf; developing to patches of cottony white mold growth, that eventually turn a grayish white to grayish brown,” said Scheidt.

Powdery mildew is favored by warm, wet or humid weather. Avoiding excess nitrogen is important in managing powdery mildew. If the disease increases, then the recommended treatment is spraying a fungicide labeled for powdery mildew. However, if powdery mildew decreases, do not spray.

Barley yellow dwarf virus vectored by bird cherry oat aphids is also being seen in area wheat fields. Symptoms include light green or yellowing to a red or purple leaf discoloration which starts at the leaf tip down and from the leaf margin in toward the center of the leaf. Threshold levels are 6 aphids/foot.

Bird Cherry Oat Aphids are small green insects with a red ring around their rear, with short cornicles, which look like tailpipes. They are usually on the underside of the leaf; in cooler temperatures, aphids may be at soil level in the crown.

A rate of 3.2 oz. /A Warrior or 3.6 oz. /A Mustang Max is recommended to control aphids; it is optimum to apply at temperatures above 60 degrees.

Winter annual weeds henbit and chickweed in wheat fields and can cause up to 37 percent yield loss. Scheidt recommends applying herbicide before these weeds flower; after flowering the seeds have already dropped. A rate of .3-.6 oz./A Nimble is recommended to control henbit and chickweed (Nimble is the generic of Harmony).

The weekly field scouting report is sponsored by University of Missouri Extension and Barton County Extension.

For more information on this scouting report, or to learn how you can receive it a week earlier by telephone, contact the MU Extension Center in Barton County at (417) 682-3579.


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