Bicarbonate material fact sheet
These products rely on a bicarbonate salt (usually potassium bicarbonate) as the active ingredient. They are promoted for use against powdery mildew diseases. The use of baking soda (sodium bicarbonate) as a fungicide is not a new idea. In Alfred C. Hottes’ A Little Book of Climbing Plants, published in 1933, mention is made of using one ounce of baking soda per gallon of water to control powdery mildew on climbing roses. The author credits the idea to a Russian plant pathologist, A. de Yaczenski (Williams and Williams 1993).