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Oak Dripping Sap: Lecanium Scale Honeydew, Not Tree Sap

Sticky "sap" raining from a water oak is honeydew from lecanium scale insects feeding in the canopy. The black coating is sooty mold growing on the honeydew.

Treatment

Apply systemic imidacloprid (Bayer Tree & Shrub®) in early April annually. It takes 1–2 years for full control as scales are protected under waxy covers.

Resource

See "Ornamental Tree/Shrub Fact Sheet" for details.

About Gardening: White Oak Weeping Sap: Slime Flux Explained; Dead Pin Oak Standing Time: St. Louis Timeline; Identifying Oak Galls: The "Hollow Bulbs" on Scrub Oak; Oak Tree Slime Flux: Managing Sap Flow and Hornet Attraction; Oak Scale Infestation: "Raining Sap" and Bumpy Limbs; Live Oak with Weeping Holes: Sapsuckers, Not Borers; Pin Oak Sap Rain: Aphid Honeydew, Not Root Damage; Diagnosing and Treating Honeydew Dripping from an Oak Tree; Aphid Honeydew on Red Oak: The Real Cause of "Sap" Dripping; Sticky Sap on Deck from Oak Tree: Lecanium Scale Solution

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