Powdery mildew is a fungal plant disease that looks like gray or white powdery spots on an infected plant's leaves. The mold is more likely to strike during warm and dry weather, and can affect vegetable plants, as well as flowering species. The mildew typically does not kill the entire infected plant, but leaves may become discolored and less productive than they ordinarily would be. Control of powdery mildew can be achieved through a number of different horticultural products, but the fungus can also be prevented and eradicated with normal household baking soda.
Mix 4 tsp. of baking soda into a gallon container that is filled with water. Add up to 2 1/2 tbsp. of a horticultural oil if desired, to prevent and treat other pests or diseases that may be affecting your plant. Horticultural oil can help control moderate and more severe infections of powdery mildew, according to Mary Louise Flint, director of the University of California Integrated Pest Management Education and Publications.
Pour some of the baking soda and water mixture into a spray bottle.
Spritz the leaves that are affected with powdery mildew with the baking soda spray. Take care not to drench the plants; the Royal New Zealand Institute of Horticulture explains that too much of the liquid can cause damage to the leaves and to the surrounding soil.
Treat the plants again with the baking soda deterrent as needed when mildew forms on the plant again. The University of Wisconsin suggests controlling powdery mildew with baking soda on a weekly basis.