Yep it's the rain and them being constantly wet. Your beans have developed a fungal disease. If you can increase air space around them and spray with a green fungicide. You may not be able to eat the beans for a while after spraying.

If you want to try it garlic is a fungicide and you wouldn't have to stop eating the beans. Whirl a whole garlic in the blender with a little water until the garlic is mush. Put in a large bottle with 3 cups of water and let sit for a day or so. strain some into a spray bottle and spray away

Read the post about-- sharing a tip I learned long ago--that might be an option for you. I would still treat the stalks but this would get rid of most of the fungus spores and save your beans. Keep the ground loose so the water drains away.