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Tricolor Beech Sticky White Flakes: Woolly Beech Aphid Infestation

Alpine, UT (zone 6B) tricolor beech shows sticky white flakes on leaf undersides (51 °F, no frost elsewhere). Owner asks if disease.

ID: Woolly Beech Aphid

Phyllaphis fagi—pale yellow aphids covered in white wax filaments. Colonies on young shoots/leaf undersides. Honeydew → sticky leaves → sooty mold. Winged forms fly midsummer.

Treatment

Now (fall): Spray Orthene (acephate) thoroughly, especially undersides. Kills current colonies.
Next spring: Soil-drench Bayer Advanced Tree & Shrub Insect Control (imidacloprid). Roots translocate to canopy; season-long protection.

Soil drench won't work now—tree shutting down. Orthene cleans up fall population.

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