Greetings. Sorry for the delay on getting your question answered. Green beans can get a spot actually on the bean itself and the leaves. This can be caused by a fungus called Anthracnose. Anthracnose can spread from season to season so it is best to destroy plants and avoid planting green beans there for 2-3 years.
Another possibility is Bean Rust -- Bean Rust is also a fungus and can result in our recent weather patterns. To control Rust you can apply a multi-purpose fungicide at the first sign of the disease. Weekly applications may be necessary. Follow the recommendation on the fungicide label.
It is important to make sure after each gardening season to clean up any debris and discard it from the garden. This can stop the spread of the disease cycle.
To determine exactly what fungus or disease your beans have please bring a sample of the plant to any extension office that is close to you. The Greenup County Extension Office is open from 8 am until 4:30 pm Monday- Friday and open during lunch. The telephone number for the office is 836-0201. Please let me know if I can assist you further.