This is the time of year that that you will start to notice infestations of the new invasive pigweeds as they climb above the soybean canopy after surviving the post herbicide program.
The first reaction for most is to look for an herbicide solution, but this can be challenging. These populations are glyphosate resistant and maybe ALS or group 2 herbicide resistant (Pursuit, Classic, etc.). Potential active soybean products are usually members of the Group 14 or PPO inhibitors like Cobra, Flexstar/Reflex, Cadet/Marvel, and Ultra Blazer, which can be effective on small seedling pigweeds. However, these herbicides will not kill the larger, more mature plants.
In addition, with some exceptions, most products should be applied no later than R2 (flowering). Of the Group 14 herbicides, Cobra (lactofen) allows application up to 45 days before harvest or R6 (full seed), Cadet or Marvel, 60 days, Flexstar/Flexstar GT/Reflex 45 days, and Ultra Blazer 50 days before harvest. Even Liberty, which can be applied up to 45 days before harvest to Liberty Link soybeans, or the new dicamba products that can be applied up to R1 for Xtend soybeans (Xtendimax, Fexapan, and Engenia) will not control these large escaped weeds. With smaller infestations, consider walking the fields and removing the weeds by hand.