Sooty Mold of Japanese Maple

Disease Information

Sooty Mold

 Symptoms and damage

A charcoal-black, powdery or velvety coating on leaves and other plant parts is the result of growth of one of the commonly occurring sooty mold fungi. The good news is that despite its appearance, the fungus is not infecting plant tissue and is not causing disease. It grows on the surface of the plant and gets its nourishment from honeydew that is excreted by sap-sucking insects such as aphids, some scales, whiteflies, leafhoppers, mealybugs and others. As these insects suck plant sap, they are unable to digest all of the sugar that they ingest. The excess is excreted as sugary liquid called honeydew. For information on controlling the insect pests whose feeding habits result in sooty mold problems, Diagnosis of sooty mold is made simple by the fact that the black fungal growth can be removed by wiping with a moist paper towel, or in some cases, by peeling it off to reveal an undamaged plant surface.

While mainly a cosmetic problem, when sooty mold is severe it can reduce the vigor of plants by blocking sunlight necessary for photosynthesis (food production). On the other hand, insect feeding can seriously damage a plant. Between insect feeding and reduced photosynthesis, the plant may be more susceptible to other insect, disease, and environmental problems.


 Since the cause of the problem is insect activity, control measures should be directed at the insects rather than the fungus. Important first steps include identifying the plant that is infested and the insect that is causing the problem. When identifying the infested plant, always look at plants growing above the gardenia as well as the gardenia itself. With a sufficiently heavy infestation of sap-sucking insects, the sticky honeydew may drip from an infested plant to non-infested plants growing below (as well as onto objects such as lawn furniture, decks, cars, etc.).

Insecticides for Gardenia Insect Pest Control (Acephate )-( Bifenthrin)-( Carbaryl)-( Cyfluthrin)-( Dinotefuran) –( Horticultural oil2)-(Imidacloprid)-( Malathion)-( Neem oil)- Spinosad) –( Pyrethrin) .


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