Elm Finger Gall vs. Maple Bladder Gall: Identification and Management

Elm Finger Gall vs. Maple Bladder Gall: Identification and Management

A young Homestead elm with protruding, color-changing galls (green to pink to red to black) near silver maples likely has elm finger gall, caused by the eriophyid mite Eriophyes ulmi—not maple bladder gall. The mites are microscopic relatives of spiders, not insects.

Key Differences

• Maple bladder gall: Round, bladder-like pouches on maple leaves.
• Elm finger gall: Elongated, finger-like projections on elm leaves.

Impact and Treatment

• Galls are cosmetic; they do not threaten tree health.
• Premature leaf drop may occur in heavy infestations.
• Treatment is rarely justified; systemic insecticides (e.g., imidacloprid) can reduce mites but are costly.
• Best practice: Maintain tree vigor with water and fertilizer; tolerate the galls.

Reference: Texas A&M AgriLife Extension – Gall Makers (link)