Corn Earworm

• They will frequently be near the tip but may feed down the ear creating a track of damaged kernels
• The injury creates an ideal environment for ear fungi to invade and may lead to a quality problem at harvest

• Latin Name: Heliothiszea
• Closely related or indistinguishable from:
  • Cotton bollworm: Helicoverpa armigera
  • Tobacco budworm: Heliothisvirescens, etc.
• Importance
  • Grain losses estimated at 2.5% annually
  • Losses in southeastern U.S. as high as 16.7%
  • Losses in sweet corn as high as 50% in unsalable produce
• Found worldwide but does not usually overwinter in most of the Corn Belt and must re-infest each year
• Large range of hosts including corn, cotton, tobacco, tomatoes and other fleshy fruits and vegetables
• In addition to the ear, occasionally larvae can be found in the whorl and foliage on younger plants

• Trapping
  • Light traps or pheromone traps can indicate when adults are flying
• Scouting
  • Scouting can be done in the field by looking for eggs on the green silks and turning back the silks at the tip of the ear to look for larvae
• Management timing
  • Because the larva is exposed outside the ear for only a short time, economical timing of insecticides is difficult
  • Stop application after silks turn brown
• Resistance available
  • Tight husks give some relief but real resistance is lacking except through the use of Bt hybrids
• Pesticide use
  • In field corn, pesticide use is rarely warranted
  • Please check local accepted practices and label instructions when growing either sweet corn, seed corn or another specialty crop

• Favorable conditions
  • Trichogramma parasites infest some eggs but control is minimal

Best Management Practices Using Pioneer Products

• Transgenic offerings
  • YieldGard® Corn Borer, Herculex® I and Herculex XTRA Insect Protection products provide suppression / moderate control of corn earworm populations
• Beware that in cotton producing counties, additional requirements for refuge are required because of cross resistance of cotton bollworm / corn earworm to the YieldGard Bt gene