Effectiveness of Insecticide Oversprays for Control of Bollworm and Stink Bugs on Bt Cotton Technology in South Carolina

Stink bugs remain the number one insect pest group of Bt cotton in the southeastern USA, and significant numbers of bollworm escape control from Bt proteins, causing economic injury, especially in 2-gene Bt cotton.  Oversprays of insecticide on Bt cotton are standard practice in the region and most often result in increased yields due to protection from one or both pests.  Pyrethroid insecticides continue to be the standard for control of stink bugs, but susceptibility of bollworm to pyrethroids is declining, and use of alternative, lep-specific insecticides for control of bollworm has increased, particularly in 2-gene Bt cotton.  We conducted a trial to parse out the injury and yield impacts of each pest (bollworm or stink bugs).  The importance of scouting and matching each Bt technology with the appropriate insecticide overspray choice cannot be overstated, and local recommendations for insecticide oversprays in Bt cotton should be followed.