We have a field a field of conventional beans that has some hemp and giant ragweed on one side(12 - 24 rows).  Think it spread in from the fense row.  Hemp was grown around here in WWII and used to make rope.  I'm sure that it made good rope as it is some tough stuff.

Sprayed it with flexstar earlier, but didn't have much effect.  We can walk it, but pulling it is not practical(unless you use a tractor).  Don't think you can cut it with a corn knife.  If you did cut it, will it grow back?  Could use a hand sprayer with 2-4d and roundup, but that will kill some beans.  Any other ideas?