Potassium Bicarbonate

3. Baking Soda
Also known as sodium bicarbonate, baking soda is a common remedy for powdery mildew. Its high pH makes it effective at treating and preventing powdery mildew, as it renders a plant’s surface too alkaline for the spores to thrive. The benefits of using baking soda to treat powdery mildew include:

It’s inexpensive and available at all food stores.
It’s easy to use. Simply mix one teaspoon of baking soda with one teaspoon of Epsom salts to create an effective treatment for powdery mildew.
A drawback to using baking soda is that it will alter the pH levels of your plants, which can in turn cause iron to become less soluble and thus less available to your crops. In this case, a plant supplement that’s rich in iron, such as Sensi Cal-Mag Xtra, can help ensure your crops receive the micronutrients they need to thrive.



4. Potassium Bicarbonate
Like baking soda, potassium bicarbonate will alter the pH levels of your crops, but it’s stronger and will kill powdery mildew quicker. An effective preventative treatment as well as a great choice for a curative remedy, simply mix three teaspoons of potassium bicarbonate with three tablespoons of vegetable oil, half a teaspoon of hand soap, and a gallon of water to create a solution that kills powdery mildew on contact.