Hi Daniel,

Ahhh, it looks like fungus is among us. I'm afraid I don't have good news for you. All this rain and humidity are causing lots of fungal issues. Once your plant has it , it's pretty hard to fix the problem. I think you have Leaf Spot;

https://edis.ifas.ufl.edu/publication/PP113

I have switched to growing different types of basil like Thai and Cinnamon that don't get fungal issues. I do have a friend that grows basil in pots and has no problems. I think they get much more air circulation.

I would cut off all diseased areas and try to get as much air circulation around the plants as possible. I'd start harvesting the good leaves and buy new plants to place in a different spot.

Sorry,

Sally Granath

St. Louis County MG