Baking Soda Spray for Tomatoes

Tomato Diseases

• Leaf spot leaves behind dark circles on tomato foliage, especially on the lower leaves. Leaf blight infected tomato plants contain brown or white lesions on the foliage. Blight will continue to spread to other tomato plants until you destroy it. Powdery mildew forms on the leaves and appears white or light green in color. A regular application of a natural fungicide prevents extensive damage from occurring.

Baking Soda Spray

• Combine 1 gallon of room temperature water with 1 tbsp. of baking soda and 2-1/2 tbsp. of vegetable oil in a garden sprayer. Stir the ingredients gently until the baking soda dissolves completely. Add 1/2 tsp. of castile soap to the solution. Spray the baking soda solution over the tomato foliage to cover the upper and lower leaves thoroughly. Continue to apply the baking soda spray every five to seven days until you control the fungal disease.

Tips and Warnings

• Spray tomato plants with water when they are infected with powdery mildew to loosen the spores so that the baking soda spray works more effectively. The sodium in baking soda can build in the soil and harm plants. The baking soda builds more when little rainfall occurs to flush it from the soil. Potassium bicarbonate and ammonium bicarbonate work more effectively, according to Purdue University. For best results, stop applying the baking soda spray if you notice plant damage or low quality tomatoes.

Other Natural Pesticides

• If baking soda does not help control a tomato disease, then try applying a different natural fungicide. Neem oil works effectively to kill powdery mildew and pests like aphids and white flies. Distilled horticultural mineral oils are combined with an emulsifying agent so that the oil can mix well with water. The oils do not work well in temperatures above 90 degrees Fahrenheit or below 40 degrees Fahrenheit. Sulfur works to control fungal spores and comes available as a dust, powder or liquid. You cannot apply sulfur in temperatures above 80 degrees Fahrenheit or after you apply an oil spray.