What's eating my augustine's rhododendron?

Augustine's rhododendron is susceptible to the same outdoor rhododendron pests: lace bug, vine weevil, and scale insects. Grown widely in UK gardens, it also faces the rhododendron leafhopper, which vectors bud blast disease. Partial shade planting and good air circulation are the best preventive measures.

Fine yellow stippling on the upper surface of leaves; brown tar-like spots of excrement on undersides. Heavy infestations dull the foliage and reduce flower production. Spray the undersides of foliage with insecticidal soap or pyrethroid in late spring. Apply imidacloprid as a soil drench for systemic protection lasting the whole season. Shade planting reduces risk.

The bright adults create egg-laying scars in flower buds, which then become infected with bud blast fungus — buds turn brown and fail to open, often persisting into the next season. Spray adults July to October with a contact insecticide. Pick off and burn blasted buds to break the disease cycle. Avoid overhead irrigation that keeps foliage wet.

Notched leaf margins from nocturnal adult feeding; larvae destroy roots, especially in containers, causing sudden wilting and collapse. Hand-pick adults at night. Use biological nematode drench (Heterorhabditis spp.) in late summer for larval control in moist soil. Apply vine weevil-registered insecticide to foliage if adults are numerous.