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 6/22/2019

Worm Control in Late-Planted Corn

Key Pests and Impact on Crop

  • Late-planted corn can be subject to increased damage from lepidopteran worm pests such as:
    • European corn borer (ECB)
    • Southwestern corn borer (SWCB)
    • Fall armyworm (FAW)
    • Corn earworm (CEW)
  • For optimum control, apply DuPont™ Prevathon® insect control before larvae tunnel into plant or ear.

European Corn Borer (ECB)

  • Apply DuPont Prevathon® insect control insect control at the V10 stage, coinciding with moth flight and egg laying, or when scouting or traps indicate presence of moths, eggs or larvae.
ECB moths

ECB moths

ECB eggss

ECB eggs

ECB eggss

ECB larvae

ECB eggss

Whorl-stage corn (approximately V10 to V12) with leaf damage due to ECB feeding. Larvae present before tasseling eventually move to the lower part of the plant and tunnel into the stalk.

ECB eggss

After ECB larvae tunnel into stalk or ear, insecticides are less effective.

Southwestern Corn Borer (SWCB)

  • Apply DuPont Prevathon® insect control prior to economic threshold of 20% to 25% infested plants or when pheromone traps indicate heavy moth flights.
ECB moths

SWCB moth and egg mass

ECB eggss

Southwestern corn borer damage to corn stalks (girdling)

Fall Armyworm (FAW)

  • Apply DuPont™ Prevathon® insect control at first indications of larvae in field edges or adjacent areas.
FAW larvae

FAW larvae

FAW adult and damage to whorl-stage corn

FAW adult and damage to whorl-stage corn

Western Bean Cutworm (WBCW)

  • Apply DuPont Prevathon insect control when scouting from late June through mid August indicate ~8% of plants have egg masses or small larvae and/or when larvae have hatched and 95% of tassels have emerged.
  • Multiple larvae per ear possible. Heavy infestations may result in 50-60% damaged kernels. Several larvae per plant can reduce grain yield by 15-20%.
WBCW eggs

WBCW eggs

WBCW damage

WBCW damage

Corn Earworm

  • Apply DuPont Prevathon insect control as part of a comprehensive CEW control program. Within this program, DuPont Prevathon insect control could be applied when scouting indicates presence of eggs and/or at brown silks for 21 days residual control.
CEW adult and small larva

CEW adult; small larva in silks and in ear tip

CEW larva

CEW larva in ear tip and feeding damage to ear

Distinguishing Armyworms and Earworms

True Armyworm (AW) - Smooth cuticle; subdued colors. DuPont Prevathon insect control is not labeled for true armyworm.

Fall Armyworm (FAW)

  • Brown/gray larva with distinct tubercles along body
  • Three thin white stripes down the back and a distinct white inverted “Y” on head (see image below)
  • Young larvae may be difficult to distinguish from corn earworm (CEW)

Corn Earworm (CEW)

  • Bright, variable colors
  • Cuticle has “unshaven” look
Armyworm, Fall Armyworm, Corn Earworm

Left to right: Armyworm, Fall Armyworm, Corn Earworm

This reference guide is not intended as a substitute for the product label for Prevathon®. The product label contains important precautions, directions for use and product warranty and liability limitations that must be read before using the product. Applicators must be in possession of the product label at the time of application. Always read and follow all label directions and precautions for use when using any pesticide alone or in tank-mix combinations.


DuPont™ and Prevathon® are trademarks or registered trademarks of E. I. du Pont de Nemours and Company or its affiliates.