Sooty Mold

    Sooty Mold

    Many fungal species

    sooty mold

    Sooty mold on California laurel (Joseph O'Brien, USDA Forest Service, Bugwood.org)

    sooty mold

    Sooty mold on branch (Whitney Cranshaw, Colorado State University, Bugwood.org)

    sooty mold

    Sooty mold on cement below aphid-infested linden tree (Whitney Cranshaw, Colorado State University, Bugwood.org)

    Hosts, Symptoms & Signs

    • any plant where aphids, soft scales, leafhoppers, whiteflies or mealybugs feed and honeydew is produced
    • black fungal growth on leaves, fruit, branches and stems
    • stunted growth or early leaf drop in severe cases
    • causes indirect damage by reducing photosynthesizing leaf surface area

    Disease Cycle

    • sooty molds are not real pathogens; they colonize the honeydew excreted from aphids and other phloem-feeding, sap-sucking insects and feed on the sugary substance 

    IPM Recommendations

    • Manage trees to improve or maintain overall health.
    • Wash off aphids with a strong stream of water.
    • Manage or exclude ants from trees to prevent them from protecting honeydew-producing insects.
    • Wash sooty mold and honeydew from plants using water.
    • Apply horticultural oils to overwintering aphid eggs and scales in spring prior to bud break.
    • Apply an insecticidal soap or pyrethroid to nymphs, crawlers and adults when present.
    • Apply a systemic insecticide (neonicitinoid) in the spring to target sap-sucking, phloem-feeding insects that produce honeydew.