Roundup beans were the best thing that came along for us for controlling sicklepod. Are you beans on wide rows that leave a lot of open area for the sicklepod to come up in? Back before RR I had better luck controlling it in cotton and I believe corn would be better than cotton for having good chemical programs for it. Back in the 80's sicklepod was our problem weed. Seems like I remember having good control with Canopy pre if we got good activation before the sicklepod came up.