Black fungal growth on the foliage of plants such as gardenias, crape myrtles, and other plants infested with aphids, scale, or whiteflies. It is caused by honeydew (excrement) of the insect pests. Best control is the release beneficial insects to control the pest bugs. Also spray Garrett Juice plus garlic. Treat soil with horticultural cornmeal and use the entire Sick Tree Treatment. PureGro Disease Stop and BioSafe are quality commercial products.