Baking Soda: Sodium bicarbonate is a product that can be used as a natural fungicide for black spot, powdery mildew and brown patch by mixing 4 teaspoons (approximately 1 rounded tablespoon) per gallon of water along with one teaspoon of mild liquid soap or horticultural oil and spraying foliage. Be careful to keep the spray on the foliage and not on the soil as much as possible. Baking soda is composed of sodium and bicarbonate ñ both are necessary in the soil but only in very small amounts. Potassium bicarbonate is a good alternative for those concerned about sodium
