What's eating my rhododendron 'catawbiense boursault'?

Rhododendron 'Catawbiense Boursault' faces vine weevil, rhododendron lacebug, and deer browsing as its primary threats. Vine weevil is the leading killer — larvae eat roots while adults notch leaf edges. Lacebug bleaches foliage in warm sites. Deer readily strip buds and young shoots in winter.

Characteristic U-shaped notches along leaf margins; larvae destroy fibrous roots, causing sudden wilting or plant death. Drench soil with biological nematodes (Steinernema kraussei) in late summer while soil is still warm. Use systemic imidacloprid for severe pot infestations.

Upper leaf surfaces develop a coarse grey-white or bronze stippling; cast skins and black tar-like excrement visible on the underside. Plant in part-shade (lacebug thrives in sunny, dry positions). Spray the underside of foliage with pyrethrum, insecticidal soap, or a systemic neonicotinoid if infestations are heavy.

Ragged browsing of flower buds and young shoots in autumn and winter, leaving torn stems rather than the clean cuts of rabbits. Erect physical deer fencing or individual guards around young plants. Spray deer repellent on foliage in autumn, reapplying after rain.

Adults feed on leaves causing minor spotting; the main harm is that leafhoppers spread Rhododendron bud blast fungal disease, turning buds black. Remove and destroy blighted buds promptly. Reduce leafhopper populations by spraying foliage with contact insecticide (pyrethrum) at petal-fall in late summer.