Aphids Seen At Threshold Level In SW Missouri Wheat
LAMAR, MO.
Jill Scheidt, agronomy specialist with University of Missouri Extension, scouted fields west of Lamar and near Iantha for the March 1 crop scouting update.
Wheat was found to be in the tillering stage.
“Wait to apply nitrogen until just before jointing stage, when nitrogen is most efficiently used. Early nitrogen applications should only be made if tiller count is below 60 tillers per square foot,” said Scheidt. “This avoids overly lush growth, which can make wheat susceptible to disease, aphids, lodging and late freeze damage.”
Twelve to twenty bird cherry oat aphids were seen per linear foot. Threshold level for bird cherry oat aphid is 12-15 per linear foot. Zero to two aphids per linear foot were seen in fields that did not have much growth.
Scout for aphids by looking on the underside of leaves; if the temperature is less than 60 degrees, be sure to look near the crown of the plant.
If aphids are at threshold level, Warrior or Mustang are labeled to treat them. Do not spray an insecticide if it is cooler than 60 degrees, aphids are not very active and hard to contact.
Light pressure from henbit, chickweed and other winter annual weeds were seen.
“Treat weeds before they flower and when less than 4” in height or diameter for the most effective control,” said Scheidt.
Winter annual weeds can reduce yield as much as 10 percent each year.
“A little septoria was seen on lower leaves in most fields. Septoria is a common disease brought on by prolonged wetness on leaf surfaces. It is unlikely to cause yield damage unless it moves up the plant and begins to cover most of the leaf surface,” said Scheidt. ∆