Important Alert for Bollgard 3, TwinLink Plus and WideStrike 3 Cotton as Bollworm / Corn Earworm Flight Begins

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Article by D. Reisig and A. Huseth

Light trap catches for bollworm (also known as corn earworm) are up this week in Craven, Duplin, Scotland and Stanly county.

Our 21 pheromone trap network has been running for a week in Northampton, Halifax, Nash, Edgecombe, and Wilson counties. Counts were highest in Wilson and southern Edgecombe. The catch was lighter moving toward Northampton county.

A metal and mesh cylinder on a cone standing on the edge of a planted field.

Bollworm pheromone trap catch 7/11-7/18/22 near Stantonsburg, NC.

This is an indication that a flight is on in the southern part of our state and that cotton at bloom should be scouted for bollworm.

We have also noticed widespread unexpected injury in corn expressing the Vip3A toxin (Leptra and Trecepta are common names). We aren’t sure why this is the case and bollworm numbers have been extremely high in corn this year. However, given this observation in corn, it is imperative that all cotton (including varieties that express the Vip3A toxin- Bollgard 3, TwinLink Plus, and WideStrike 3) is scouted for bollworm this year. We are not recommending any changes to thresholds or management this year. Be sure to use an insecticide with chlorantraniliprole as the active ingredient.

Our thresholds are:

Bollgard II, TwinLink, WideStrike:

  • 25 total eggs on 100 leaves or fruiting structures (search throughout the canopy on multiple plants)

Bollgard 3, TwinLink Plus, WideStrike 3:

  • 4% damaged bolls (this is the preferred threshold)


  • 3 live second-stage bollworms (1/8 inch or longer) per 100 fruit (pay particular attention to bollworms in or under yellow, pink, or dried blooms stuck to young bolls), or
  • 2 second-stage bollworms on 2 consecutive scouting trips, or
  • 1 second-stage bollworm on 3 consecutive scouting trips
Laral size chart