I use neem oil when I'm cloning, and that helps keep the mold from starting. It's not super effective in stopping fungus/mold once it's already started, but pretty good at preventing it from starting in the first place. Works really well for preventing powdery mildew from forming on foliage, especially if used while they're still young, andf have had a chance to absorb it into their system. Also helps protect against bud mold. It's not a cure-all, but definitely worth using. Plus, it keeps the spider mites away too.(they're natural ememies,'cause the neem renders them sterile)