Organic Cures for Leaf Mildew

Garden Control

• Baking soda mixed with a lightweight horticultural oil, such as neem oil, makes an acceptable organic powdery mildew control solution. Colorado State University Extension suggests mixing it at a ratio of 1 tablespoon baking soda with 2 1/2 tablespoons of horticultural oil into 1 gallon of water. Spraying the solution on the plant may harm it if the temperature is above 90 degrees Fahrenheit. The solution is the most effective it is sprayed on the plant at the first signs of infection.

Greenhouse Control

• University of Florida IFAS Extension suggests spraying cow's milk on greenhouse-grown zucchini plants that suffer from powdery mildew to eliminate the problem. Cow's milk appears to be an effective treatment for Podosphaera xanthii, according to a 1999 study in "Crop Protection," cited by the extension. The University of Florida's IFAS Extension further suggests that it may be the salts, amino acids, or an antimicrobial agent that controls the fungus. Greenhouse grown plants such as cucumbers appear to respond to the addition of silicon to the water to control and eliminate powdery mildew.

Alternative Sprays

• Foliar sprays that contain chlorite mica clay help to cure powdery mildew as well. A broad-spectrum fungicide that contains hydrogen dioxide as the active ingredient stops the fungus from producing spores and effectively kills it. Biofungicides -- made up of fungal spores of Ampelomyces quisqualis -- effectively kill and destroy powdery mildew fungus. In the greenhouse, biofungicides made from the yeast-like fungus Sporothrix flocculosa also control powdery mildew. The largest drawback to biofungicides is that they do not remain active if the humidity is not high.

Treatment

• Plants suffering from powdery mildew require saturation with one of the control sprays to successfully eradicate the disorder. You should also consider planting powdery mildew-resistant cultivators in any planting location that commonly suffers from fungal infection. Begin treating any plant that suffers from powdery mildew at the first signs of symptoms. Prompt treatment helps prevent the fungus from spreading throughout the landscape. If a plant suffers widespread destruction from the fungus, consider discarding it. Spraying the plant at seven- to 10-day intervals during the warm summer months to control the fungus.