Looks like Gly resistant giant ragweed, not certain but has the right profile. If you can get your hands on a wick and wipe on 2-4-D, pasture guard or crossbow that would take it out. A wick will allow you to wipe the chemical on the weed without getting it on your beans.
There is a product called "Extreme" that is Roundup and pursuit blended that I have used with some success but you will have to mow first then spray when the giant ragweed suckers out and begins new. Do not mix this product stronger than suggested as it will burn the beans. Do use a non-ionic surfactant with this.
How many acres? Is spot spraying an option?