What happened to my basil?
Your basil plant has been subject to downy mildew, unfortunately. Check the undersides of the leaves for fuzzy gray sporulation. All you can do is pull up the plant and discard it; there is no cure for this disease. There are some new varieties of basil that are resistant to basil downy mildew. They are listed on our webpage. Look for these types to plant next year. https://extension.umd.edu/hgic/downy-mildew-basil