What's eating my green gem boxwood?

Green Gem Boxwood faces three serious threats: boxwood leafminer, which causes blistered foliage; boxwood psyllid causing cupped leaves; and box blight, a fungal disease that can defoliate a plant within weeks. In the UK, box tree caterpillar (Cydalima perspectalis) is now the single most destructive pest of all Buxus and must be treated promptly.

Blistered, yellowing leaves with orange-brown blotches on the lower surface; larvae mine inside leaf tissue from summer through winter. Apply systemic insecticide (imidacloprid or acephate) in spring when adults are flying. Remove and dispose of heavily mined stems. Monitor with yellow sticky traps.

Webbing inside the shrub, rapid defoliation, green-striped caterpillars on stems; can strip a plant to bare twigs within days. Inspect plants monthly from spring. Apply Bt (Bacillus thuringiensis var. kurstaki) or spinosad targeting young caterpillars. Remove webbed nests by hand. Pyrethrin-based sprays for heavy infestations. Multiple applications needed per season.

Tan-brown leaf spots with dark borders; rapid defoliation leaving bare stems; streaky black cankers on stems. Spreads quickly in wet weather. Remove and bin all infected material — do not compost. Apply fungicides (tebuconazole, trifloxystrobin) preventively in spring and autumn. Avoid overhead watering; improve airflow by opening up the canopy.

Cupped, puckered new shoots in spring caused by nymph feeding; white waxy fluff visible in cupped leaves. Infestations are mostly cosmetic. Prune affected shoot tips in late spring. Insecticidal soap or pyrethrin spray targeting nymphs before they are enclosed in cupped leaves.