Potassium Bicarbonate, possible solution for tomato fungal problems such as black spot and yellow leaves. Discussion in comments on this review: http://www.amazon.com/review/R1UHPWEV3ZWACE/ref=cm_cr_pr_cmt?ie=UTF8=B001EJKXEO===#wasThisHelpful
Preventing Lawn Diseases : A solution containing either sodium or potassium bicarbonate--baking soda mixed at the rate of two tablespoons per gallon of water--will control a number of fungal diseases in the lawn.
Leaf Spots on basil: 3 fungal leaf spots caused by Cercospora spp. Alternaria spp. & Colletotrichum spp. To reduce incidence of foliar disease always water @base of plants & never wet leaves w/sprinklers.Pull off & dispose of diseased foliage @1st sign of disease. 4 minor fungal foliar disease spray weekly w/fungicide containing potassium bicarbonate, such as Bonide Remedy or GreenCure Organic Fungicide. - http://www.clemson.edu/extension/hgic/plants/vegetables/crops/hgic1327.html
Baking Soda/ Potassium Bicarbonate Fungus Control Mix 4 teaspoons (about 1 rounded tablespoon) of baking soda and 1 tablespoon of horticultural oil into one gallon of water. Spray lightly on foliage of plants afflicted with black spot, powdery mildew, brown patch and other fungal diseases. Avoid over-using or pouring on the soil. Potassium bicarbonate is a good substitute for baking soda. Citrus oil and molasses can be used instead of horticultural oil.