Greetings Kim,
Aphids excrete a sugary substance known as honeydew. Honeydew commonly coats leaves, branches, bark, patio furniture, automobiles, etc. Moreover, honeydew commonly creates a perfect condition for the growth of sooty mold – a black-like fungus. Sooty mold growth on plants may cause a darkened appearance on affected foliage. If severe, sooty mold may limit the photosynthetic capacity of the affected plant(s).
General Control of Aphids ~
Natural Biological Controls: More often than not, natural predators such as parasitic wasps, lady beetles, syrphid fly, and lacewings will keep local aphid populations in check.
Water: Spray the affected plant/tree with high-volume or high-pressure stream of water from a hose. Make sure to target the underside of the foliage. Use of water can also remove recently dropped honeydew.
Pesticides: It is generally recommended to use pesticides as a method of last resort, unless you have an aphid infestation. Several insecticides labeled for control of aphids includes acephate (Orthene) and malathion. Note: Always read product and pesticide labels prior to application. Always follow recommended rates and directions.
My suggestion, try the high-volume or high-pressure water hose route first!
