High Numbers Of Sugarcane Aphid In Milo

LAMAR, MO.
   Jill Scheidt, agronomy specialist with University of Missouri Extension, scouted soybeans near Arcola and south and west of Golden City on Sept. 22.
   Scheidt observed soybeans in the seed development and full seed stages.
  “Defoliation pressure from grasshopper and blister beetle was at three to ten percent,” said Scheidt.
   Threshold level for foliage feeding insects is 20 percent defoliation after bloom.
   “One to three percent pod feeding was seen, the threshold level is five percent; however, the feeding was old and no pod feeding insects were seen. One to two green stinkbugs per foot of row were seen, threshold level is one green stinkbug per foot of row,” said Scheidt.
   Green stinkbugs cause delayed maturity and reduced seed quality. Scheidt recommends using an insecticide when threshold levels are reached and insects are present.
   Scheidt observed frog eye leaf spot was seen on upper leaves that is not spreading due to dry weather. Frog eye leaf spot can be identified by light colored lesions with a dark purple-brown or dark red border on the upper and lower leaf surface.
   “Septoria was on lower leaves. It is the most common soybean disease, but usually does not require treatment,” said Scheidt. “Septoria is identified by yellow leaves with small brown spots that may prematurely drop.”
   Scheidt observed sugarcane aphids at above threshold level in milo fields in Dade county and Sudan hay fields in Stone and Lawrence counties. Threshold during head to maturity stage is seven hundred fifty aphids per plant with two to three dead leaves.
   “Late season infestations can reduce grain size and test weight. They may have less yield impact, but produce honey dew, which is a sticky substance that can clog combines. Early harvest or setting the header higher is recommended,” said Scheidt.
   Sugar aphids are light yellow in color and are found on the underside of the leaf. They have piercing, sucking mouthparts which they use to suck sap from leaves and inject a toxin which causes red discoloration, similar looking to Barley Yellow Dwarf Virus in wheat. ∆









Sugarcane aphid
Photo credit: MU Extension