I got some stuff from Costco to take care of mold and mildew on the garden fence. It's called "Wet and Forget" and that what you do. It mixes one part ot 5 parts water and I used a tank sprayer on the fence. I've also used it in a plastic spray bottle to kill mold on the inside of a couple of window frames in the house.
The section of fence I did a year ago is still free of mold and mildew. It this climate, that's close to miraculous!
Frank and Eileen
No longer RVers or FR owners