Certified GKH Gardening Expert
This appears to be a bad fungal issue in the soil. There are a few things you can do.
I prefer applying dolomitic lime and wettable sulfur to the soil. This will kill the infection, and bring back the pH to a more suitable level.
Here is a link that will help: https://www.gardeningknowhow.com/edible/vegetables/beans/information-on-common-bean-problems-tips-on-growing-beans.htm