What's eating my firethorn bonsai?

Firethorn bonsai (Pyracantha coccinea) is most damaged by woolly aphids, which crust over stems with white wool, and by fire blight bacteria that rapidly blackens and kills shoots. Scab fungus disfigures berries. Hawthorn webber moth caterpillars web and skeletonise leaves. Scale insects and spider mites appear on weakened bonsai kept in warm, dry conditions.

White cottony masses on stems, in bark crevices, and on roots; galls and bark cracking; ants tending colonies; overall weakening and shoot die-back Scrub off with methylated-spirits-dipped brush; systemic insecticide (thiacloprid or imidacloprid) for persistent or root infestations; inspect roots every time you repot

Shoot tips wilt and turn brown as if scorched, hanging in a characteristic 'shepherd's crook'; flowers and berries blacken; disease tracks down stems rapidly Cut 30 cm below all visible infection, sterilising tools with 10% bleach between cuts; remove all affected material from the site; no curative spray — copper fungicide at flowering may reduce new infection

Olive-brown or black scabby lesions on leaves, young shoots, and berries; berries turn black and fall early; defoliating in wet summers Improve air circulation through careful pruning; apply myclobutanil or trifloxystrobin fungicide from bud break; collect and destroy fallen leaves; choose resistant varieties if replanting

Silken webs enclosing clusters of leaves; caterpillars eat leaves down to the veins inside the web; multiple attacks can severely weaken a bonsai Remove webs and caterpillars by hand; spray with Bt (Bacillus thuringiensis) or pyrethroid into the web in spring; improve inspection frequency in May–June