plant disease characterized by splotchy black stain or coating on leaves, stems, and fruit, composed of dark fungal threads (Capnodium, Fumago, and Scorias species) that grow in flowing sap or on honeydew excreted by aphids and other sucking insects. The condition is unsightly but usually not harmful. Control includes spraying or dusting for sucking insects, washing off sticky coatings of sap or honeydew on plant surfaces, and avoiding the wounding of plants.