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Red Bumps on Young Maple Leaves: Harmless Leaf Galls

A young ‘Sienna’ maple has small red bumps on leaves. These are leaf galls caused by eriophyid mites or gall midges laying eggs and secreting growth-regulating chemicals.

Key Facts

Cosmetic only—no health impact.
Mite/midge population varies yearly with weather.
Galls protect inhabitants from sprays.
No treatment needed or effective.

Focus on Tree Vigor

Water during dry spells (1″/week).
Mulch 2–3″ to drip line.
Fertilize lightly in fall if soil test indicates need.

Galls are a curiosity, not a crisis. Enjoy the tree’s growth.

Trees: Maple Leaf Galls: Harmless Insect Structures, No Human Risk; Red Bumps on One Maple Only: Insect Galls, Not Disease; Silver Maple Base Sprouts Only: Root Stress and Canopy Loss; Red Bumps on Maple Leaves? Harmless Gall Wasps — No Treatment Needed; Maple Leaf Galls: Identify Before Replacing Tree; Maple Spindle Galls: Cosmetic Only, No Treatment Needed; Oak Leaf Galls: Identifying Those Colorful Bumps on Your Tree; Maple Bladder Galls: Cosmetic Mite Damage; Maple Leaf Galls: Harmless, No Treatment Needed; Maple Spindle Gall Mites: Cosmetic Only

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