Try 3% hydrogen peroxide ratio by mixing one teaspoon with one cup of water to make a spray. Try on a little area first incase it might kill your herbs. Go to gardeningknowhowdotcom for more info.

use 1 cap antiseptic mouthwash amber color, 2 tablespoons white vinegar, and full with water a small spray bottle. spray plant and soil. 2-3 times a week. it wont hurt you or plants. kills foot fungi to.