How late should you treat soybeans? Recent research from Maryland and Suffolk, VA, showed that stink bugs can damage soybeans during R6. In the cage studies, where damage was experienced at R6, stink bugs were infested at levels of 8 per row foot (link to published study).
Compare that to published threshold levels of one per row foot (thresholds found here). While we should remain vigilant, these levels are rarely experienced. Stink bugs can still damage soybeans through R7, but much less so than during the previous stages. Seed producers should be more conservative to preserve germination quality.
Also keep in mind that stink bugs are reproducing in soybeans right now. Any nymphs that develop in the crop will slowly disperse to overwintering sites from now through the rest of the fall. It is pretty unlikely that adult stink bugs will invade a field. Those that developed from nymphs in soybean have overwintering on their mind. Those that developed during the summer are probably already in soybeans and have reproduction on their mind.
Me? I’ve got the weekend on my mind. Please get out and scout if you haven’t!