Cottony Substance on Oak Leaves: Cottony Aphids

Contact sprays: acephate, bifenthrin, malathion, pyrethrum, etc.
Systemic: acephate or imidacloprid soil drench.

Cotton-like material on low oak leaves only. Owner asks what it is and if treatment needed.

ID: Cottony Aphids

Touch test: if it moves, it's insects. Sticky honeydew likely present.

Treat if honeydew/sooty mold is a nuisance; otherwise, natural enemies often handle it.

Trees: Oak Tree Dripping Sap? It's Honeydew from Aphids or Scale; Why Is One Oak Dropping Leaves Early? Genetic Variation Explained; Oak Tree Losing Inner Leaves: Normal Self-Pruning; Sticky Sap on Pin Oak: Aphids or Scale, Not Disease; Sooty Mold and Honeydew on Oak in South Africa; Red Bell-Shaped Bumps on Oak Leaves: Gall Wasps, Not a Threat; Sticky Sap Dripping from Oak: Aphids or Scale; Cottony Aphids on California Valley Oak; Weeping Oak Sap: Aphid Honeydew, Not Tree Sap; Black Leaves on Ornamental Pear: Sooty Mold from Aphids

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