Aphid Numbers Increase In Wheat Fields

LAMAR, MO.
   Wheat is in the joint stage according to Jill Scheidt, agronomy specialist with University of Missouri Extension. Scheidt scouted fields in Arcola and east of Irwin on April 15.
   “Apply nitrogen as quickly as possible to avoid burning leaves and damaging plants, if an application is needed,” said Scheidt.
   Nitrogen applications just before the joint stage will offer the greatest benefit to yield because it supplies the plant just before its greatest need for nitrogen.
   One to six bird cherry oat aphids per foot of row, threshold is 12-15 per foot of row and 120 greenbug aphids per foot of row were seen, threshold level is 300-500 per foot of row. Apply 1.3 to 1.9oz/acre of Warrior or 3.2 to 4oz/acre of Mustang to control aphids at threshold levels.
   “Aphids vector barley yellow dwarf virus which causes a yield reduction due to shriveled, light weight kernels. Barley yellow dwarf virus is identified by stunted plants that are mottled yellow-red in color, especially near the tip of the leaf,” said Scheidt.
   Scheidt recommends scouting for aphids on the underside of leaves and when it is cooler, scout for aphids near the crown of the plant, as they move closer to the ground when it is colder.
   “If corn is up, scout for black cutworms near the base of the plant and up to 2 inches deep in the soil. Scout until corn has reached the 8-leaf stage,” said Scheidt.
   Black cutworms are gray to black colored worms that curl into a “C”-shape when disturbed. “Black cutworms can clip corn plants at or just above soil level," said Scheidt.
   According to Scheidt, no significant black cutworm moth numbers have been caught in insect traps located just east of Lamar. ∆