Maple Spindle Gall Mites: Timing Sprays for Control

The spindle-shaped galls on your maple leaves are caused by maple spindle gall mites (Vasates aceriscrumena). The mites are microscopic; the galls are the plant's reaction to their feeding.

Key Insight

• Galls are cosmetic only—they don't harm tree health.
• Leaf drop from heavy galling is temporary; tree refushes.
• Sprays only work BEFORE galls form. Once galls are visible, mites are protected inside.

Effective Treatment (If You Must)

1. Timing: Spray at bud break (when leaves first emerge), before mites enter tissue.
2. Products: Bifenthrin (Talstar, Ortho Max), carbaryl (Sevin), or horticultural oil.
3. Repeat in 7–10 days if cool/wet spring prolongs emergence.

Branch Dieback?

The leafless branches and recent drop are not caused by gall mites. Check for:

• Verticillium wilt (sudden wilting, streaked wood)
• Girdling roots
• Borer damage
• Drought stress

→ Get an arborist evaluation for the dieback.

Don't panic over galls. Focus on the real issue: why are major branches dying?