I'm guessing that you've got some sort of disease going on, probably a fungus of sorts. Better to yank them and start again. In AP, you don't have the luxury of crop rotation b/c the same water system feeds all of the plants. So, not sure what to do in that case. Brassicas are supposed to be good at combatting fungus in the soil. Next time around, you might try a garlic foliar spray for your beans.