I use Neem Oil as a treatment for powdery mildew. Dyna-Gro directions says to use 1/2 tsp. per quart of water plus dish soap (1- 1/2 tsp.)as an emulsifier. (If mixing a gal. 1 oz. each). I put it in a spray bottle and shake before each use. I usually don't throw out the mix and re use it. I have also cut this in half, because I usually only have a couple at a time that get PM. Several days later I re spray. Have read it coats the fungal spores then dehydrates them to stop the cycle. I usually cut blooms, but once I left blooms on and sprayed (drenched it -drops rolling off bloom) the next day PM was gone from the bloom and the bloom wasn't damaged at all - unlike Lysol spray. Also on an occasion while grooming I will spray on leaves because it makes them shiny.