Listed by the Organic Materials Review Institute (OMRI) for use in organic production, Bi-Carb's active ingredient is a microencapsulated form of good old baking soda. It works by disrupting the potassium ion balance in the fungus that causes powdery mildew, causing the cell walls to collapse. Use it for a natural control of powdery mildew on Roses, vegetables, herbs, Grapes, fruit trees, and ornamentals.
For best results, begin spraying at the first sign of disease. For foliage, mix 2 teaspoons Bi-Carb to 1 gallon of water, and apply with a hand-held sprayer to cover leaves thoroughly. For lawn applications, one 4oz bottle makes 12 gallons of spray, which covers 6,000sq ft. Direct contact is essential for control. Apply spray within 24 hours after mixing.