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Oak Tree Honeydew on Cars: Aphid/Scale Systemic Fix

Sudden sticky sap (thick drops and long drippings) on cars under three oaks. Also dime-sized sticky spots on patio under outer branches.

Cause: Aphids or Scale

Sucking insects secrete honeydew (sticky, sugary). Leads to sooty mold.

Treatment

Soil-applied systemic: Imidacloprid (Bayer Advanced Garden Tree & Shrub Insect Control) — best for large trees. Roots absorb, transport to canopy.

Contact sprays (Orthene, Talstar, Dursban, etc.) difficult on large trees. Systemic lasts months.

Link: Product info

Trees: Oak Tree Dripping Sap? It's Honeydew from Aphids or Scale; Laurel Oak Raining Sap: Scale Insects, Soil Drench Fix; Oak "Sap" Problem: Actually Honeydew from Insects; Diagnosing and Treating Sap-Oozing Oak Trees; Hackberry "Sap" on Truck: It's Honeydew from Aphids/Scale; Sticky Sap Dripping from Oak: Aphids or Scale; Cottony Aphids on California Valley Oak; Black Walnut Sap on Treated Wood Arbor: No Damage; Black Walnut Honeydew: Aphid Control on Large Trees; Pin Oak Sap Rain: Aphid Honeydew, Not Root Damage

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