Potassium Bicarbonate Fungicide
Mix 4 teaspoons (about 1 rounded tablespoon) of potassium bicarbonate into one gallon of water. Spray lightly on foliage of plants afflicted with black spot, powdery mildew, brown patch and other fungal diseases. Potassium bicarbonate is a good substitute for baking soda. There are commercial EPA registered as well as generic products available.
Food grade potassium carbonate is used to adjust Ph levels in finished wine, according to one supplier. It is introduced into the wine prior to fining (removing unwanted material while still in the cellar) and operates most effectively while the wine undergoes cold stabilization. It is also sold as an acid reduction product (used like bicarbonate of soda).