Spray on Simple Green. Wipe or hose off. Easy to use and works great
Use spirits of salt in a spray canister and spray undiluted over fungus. Immediately kills fungus and cleans wall. Neutralize with water. Be careful not to get into eyes. Use face shield.
Wet and forget might be an option to consider
I put a little bleach and some tide in a spray canister and hook it to your hose and spray it off