Soybean Insect Scouting Update

David Owens, Extension Entomologist, and Bill Cissel, Extension Agent – Integrated Pest Management;

Corn earworm, stink bugs, bean leaf beetles, and soybean loopers are the primary insect pests present in soybean. So far, only low numbers of earworms and loopers have been found, but we are seeing moth activity in fields and our pheromone traps have been capturing more earworms than last week. If loopers are present, use defoliation thresholds and keep in mind that pyrethroid resistance is prevalent in southern states. Corn earworms are also demonstrating reduced pyrethroid susceptibility. If a field is at threshold or only slightly above threshold (please visit the CEW threshold calculator and enter your application cost, soybean value, row spacing: ( and the worms are small, pyrethroids should knock them back enough. If large numbers of worms are present, other useful products include Intrepid Edge, Steward, Radiant, or a diamide containing product (Besiege, Prevathon). Also note that if stink bugs are present at threshold (5 per 15 sweeps grain, 2.5 per 15 sweeps for seed) a pyrethroid will be necessary. We also continue to find low numbers of aphids. Thresholds are 250 per plant on most plants, with increasing numbers of aphids up until R6. After R6, aphid injury is inconsistent. In addition to defoliating, bean leaf beetles can feed on pods. Treatment may be necessary if 3- 4 beetles are present per sweep and 10% of the pods have been fed upon.

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