What's eating my guelder rose?

Guelder rose is one of the primary host plants for the viburnum leaf beetle and snowball aphid — both can cause near-total defoliation. Viburnum leaf beetle is the most destructive, with both larvae and adults stripping foliage to bare stems. Birds eat the berries harmlessly. Early spring action against larvae is the most effective timing.

Pale-green larvae skeletonize leaves from May, leaving only veins. Adults continue feeding through summer, resulting in heavily defoliated plants. Repeated attacks over 2–3 years can kill the shrub. Prune out egg-infested twig tips between October and April. Apply horticultural oil to twigs before budbreak to smother eggs. Spray larvae in late April with bifenthrin, cypermethrin, or permethrin when they first emerge.

Grey-green aphids cluster at shoot tips in spring, causing severe leaf curl and distortion. Viburnum opulus is a preferred host; colonies can be dense and disfiguring. Apply insecticidal soap or neem oil spray when colonies first appear in spring before leaves fully curl around them. Encourage natural predators (ladybirds, lacewings). Systemic insecticide (thiacloprid or acetamiprid where registered) for heavy infestations.

Nymphs cluster on leaf undersides and excrete honeydew, leading to black sooty mould on upper leaf surfaces. In UK gardens this is a secondary but recurring problem on Viburnum opulus. Spray leaf undersides with insecticidal soap, pyrethrin, or neem oil in spring and summer. Yellow sticky traps monitor adult numbers. Several applications are needed as eggs are protected.