Made with certified organic soybean oil, Fungus Pharm does a great job when used weekly to prevent powdery mildew, control rusts, black spots and more. Please water plants to be treated in the AM, then at dusk, spray a fine even mist on the stems, leaves top and bottom and in the case of trees, the entire trunk where eggs are wintering over. Spraying in the evening lengthens drying time allowing the oils to penetrate the cell wall of the fungus and break it down.