The flower buds of rhododendrons affected by bud blast disease fail to open, so ruining any chance of a colourful spring display of flowers.
Rhododendron bud blast is a fungal disease spread by the rhododendron leafhopper. This insect lays its eggs on the developing flower buds of these plants.
The flower buds of rhododendron turn silvery in colour and show black bristles before eventually falling off without opening.
Treatment and control
Carefully pick off any affected buds and dispose of them in the dustbin. Make sure not to spread the disease from affected buds to unaffected ones.
Spray with a general insecticide: Keep plants free of leafhoppers, especially when the female adults are laying egg from July to October.