Aphids found at threshold in area wheat fields
Bird Cherry Oat Aphids were seen at threshold levels in wheat fields when Jill Scheidt, agronomy specialist with University of Missouri Extension in Barton County, scouted area fields on April 10.
“Bird Cherry Oat Aphids are small green insects identified by a red ring around their rear with cornicles, which appear to look like tailpipes,” said Scheidt.
Threshold levels for Bird Cherry Oat Aphid are 10 per foot if wheat is 60 days or more past emergence. A rate of 3.2 ounces per acre Warrior or 3.6 ounces per acre Mustang Max is recommended to control aphids.
“Bird Cherry Oat Aphids vector Barley Yellow Dwarf Virus, which causes stunting of plants and possible yield loss and should be treated for until the flag leaf is present,” Scheidt said.
Powdery mildew continues to fade in area fields and is unlikely to need treatment. Look for powdery mildew, a gray to white mold on leaves, during the flag leaf stage. If a disease is present on the flag leaf or moving up the plant toward the flag leaf, a fungicide application is recommended.
Yellowing was also seen in low areas of wheat fields due to temporary nutrient deficiency caused by excessive water in low areas.
“The majority of wheat is looking healthy and green and may begin jointing soon. Jointing stage is identified by locating the main stem and running your fingers along the stem, beginning at the base, until you feel a bump. Jointing has begun when the bump is easily identified and if the stem is cut open, the wheat head can be found beginning to form,” said Scheidt.
Alfalfa weevils have been seen at threshold levels. According to MU state entomologist Wayne Bailey, to determine threshold levels collect 10 random stems and bang them in a bucket. If you collect one weevil per stem or close to that treatment is justified. A medium rate of Warrior II, Lorsban or Pincap is suggested.
The weekly field scouting report is sponsored by University of Missouri Extension and Barton County Extension.