What's eating my japanese maple 'sango kaku'?

Acer palmatum 'Sango Kaku' (Coral Bark Maple) is vulnerable to aphids, scale insects, and gall mites like all Japanese maples. Its vivid coral bark makes scale infestations especially visible. Deer may browse young stems in winter. Maintain tree health and blast aphids with water before resorting to other controls.

Feed on new spring growth, causing distorted, sticky, and sooty-mould-covered shoot tips. Heavy colonies can stunt seasonal extension growth. High-pressure water spray is the safest and most effective control — do not apply horticultural oil to maples. Encourage aphid predators. Remove and bag infested tips.

Oyster-shell or cottony white encrustations on the coral bark; sap-sucking weakens stems and dieback appears in severe multi-year infestations. Apply horticultural oil in late winter. Follow up with a crawler-stage spray in late spring. Improve air circulation by selective pruning of crowded stems.

Red or green pimple-like galls erupt on leaf surfaces in spring; unsightly but almost never cause significant health problems for established trees. No chemical treatment available or necessary. Remove affected leaves for aesthetics. Ensure adequate water during dry spells to maintain tree vigour.