What's eating my japanese barberry?

Japanese Barberry's sharp thorns deter large grazers but it still attracts barberry aphids in spring and scale insects on mature stems. Verticillium wilt is the main disease threat, but among animal pests, rabbits occasionally gnaw young stems near the base. Aphids are the most common insect pest; treat with insecticidal soap at the first sign.

Yellow-green colonies on new shoot tips in spring distort and curl young leaves; heavily infested tips may die back, and honeydew attracts ants along the thorny stems. Knock colonies off with a firm water jet. Apply insecticidal soap or neem oil to shoot tips every 4–5 days. Natural predators such as ladybugs and parasitic wasps usually bring populations under control without further intervention.

Hard or soft brown bumps adhered to older stems and branches; persistent infestations cause branch dieback and yellowing foliage, most noticeable in late summer. Apply dormant-rate horticultural oil to bare stems in late winter before bud break to smother overwintering eggs. Summer-weight horticultural oil handles active crawlers. Prune and remove badly affected stems.

Rabbits gnaw and strip bark from the base of young stems in winter and early spring, leaving clean-cut diagonal bite marks despite the thorns on older wood. Wrap the base of young shrubs with wire mesh cylinder guards (at least 60 cm / 24 in high) in autumn. Apply rabbit repellent to lower stems and reapply after rain during the vulnerable winter period.