As we move into mid-July, it is time to be out scouting full-season planted soybeans that have pods currently developing. Dr. Dominic Reisig (NC State Extension Specialist) confirmed that corn earworms are both early and heavy this year. Dr. Reisig recently published an article detailing corn earworm management, especially addressing how to handle Corn Earworm in Flowering Soybeans. In the article Dr. Reisig states: Several effective insecticides are available for corn earworm in soybeans, including Blackhawk, Denim, Intrepid Edge, Steward, and Vertento. Avoid broad-spectrum insecticides, such as acephate or pyrethroids, unless they are needed for another insect pest (stink bugs or bean leaf beetles). These products can remove beneficial insects and may cause other pests to flare. We have data showing that broad-spectrum insecticides can flare soybean loopers, and spider mites have also been flared in recent years. Finally, do not use Besiege, Elevest, or Vantacor in soybeans. Not applying Diamide insecticides (containing chlorantraniliprole) to soybean preserves their efficacy and delays resistance in cotton, where these products are critical for controlling corn earworms and other Bt-resistant pests.

Thresholds for Treatment

Please note that these corn earworm and stinkbug thresholds apply to podding soybeans.

Corn Earworms

Our threshold is dynamic and calculated using the NC State Extension Corn Earworm Economic Threshold Calculator. This tool utilizes your specific inputs, including control costs, soybean market price, row width, and your sampling method to generate a tailored threshold for your specific operation.

Stink Bugs

The action threshold is 5 stink bugs per 15 sweeps of a sweep net for 7-21 inch wide row soybeans (reduced to 2.5 per 15 sweeps for seed or edible beans).

Defoliation Thresholds (All Growth Stages)

NC State has recently made Important Change to North Carolina Soybean Defoliation Thresholds After Beginning Flowering (R1). The updated guidelines are listed below:

• Vegetative Growth Stages: 30% of the canopy- for both full-season soybean (planted prior to June 1) and double-cropped soybean (planted after May 31)
• After bloom: 25% of the canopy- full-season soybean (planted prior to June 1).
• After bloom: 15% of the canopy- double-cropped soybean (planted after May 31)

If you have any further questions, contact the Hertford County Extension Center at 252-358-7822.