Hello,

Based on the images you sent, I believe your beans are affected by either bacterial brown spot or common blight. Both are caused by bacteria. The recent rain and cooler temperature along with high humidity could be the culprits.

Based on university research sites and their descriptions the cause could bacterial brown spot. https://www.vegetables.cornell.edu/pest-management/disease-factsheets/bacterial-brown-spot-of-bean/ I don't see any water-soaked spots on your beans, and they don't appear twisted, but the water-soaked lesion could have happened before harvesting.

The other possibility is common blight. https://extension.colostate.edu/topic-areas/agriculture/bacterial-diseases-of-beans-2-913/. Both bacteria will cause brown spots on the pods.

This resource describes 3 possibilities (halo blight is unlikely) but gives a good overview. https://www.vegetables.cornell.edu/pest-management/disease-factsheets/bacterial-diseases-of-beans/

The links also show the bean leaves which can aid in determination. Regardless, the bacteria can enter the soil  and stick around in any leaf or bean debris. The best remedy is to throughly clean up the bean area and then practice crop rotation next year, planting corn, cucurbits , tomatoes or onions where the beans have been.  There are also disease resistant bean varieties to try. Many seed catalogs indicate resistance. 

There is no treatment once the beans have been infected, there are only preventative options. The bacteria causing the infections are plant pathogens, meaning they only infect plants. Stating the obvious, you could cut away the heavily infected portions in those beans which are not completely covered with spots.

I hope this information is useful.

Sabine

I am glad to hear that you have far fewer brown spots on your beans. I am sure the heat and dryness helped. Enjoy your fresh green beans. 

Sabine