I use neem oil from garden safe (found at Walmart and Lowes) it works well as a preventative for mould, mildew, and some insects. I've since switched to Einstein oil its the same in a sense, neem oil is its main ingredient. Hindsight being 20/20 I'd wish I had gotten dynagro neem oil, because I use protekt from Dynagro. Protekt is an emulsifier, also a silicon supplement, it helps keep things mixed, with added benefits of making plants more resistant to drought, heat and stress, it also thickens cell walls to help naturally fight against pest and disease. You also want a good surfactant. Many use dawn dish washing liquid. I use non concentrate myself, just a drop. Any neem oil should help. Make sure plants aren't under any kind of stress water wise, more so, if you think they need water, water them before treatment. I just learned that the hard way. Plants were slightly under watered, and I hit them hard with oil. Burnt leaves and stress was the result. Be careful, start small, and may the grow gods bless you.