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Rhododendron Bud Blast

Symptoms

The symptoms of bud blast can be recognised when the buds fail to open and internally dry up, turning brown before they die. They can remain like this for several years. When the bud is looked at in further detail, the surface of the bud is found to be covered in tiny bristles which are the fungi outgrowth. This is the spore baring part of the fungi.

Cycle of Infection

This fungus seems to infect in mid to late summer due to the Rhododendron leafhopper (nymph). This insect spreads the fungi that cause the bud blast.

Implications for host

The leafhoppers appear in mid to late summer when the weather is hot, and they come in droves. This sap-eating insect doesn’t directly harm the plant by feeding on the sap, but when it lays its eggs in the bud scales, it leaves the Rhododendron open to infection. Though the buds are infected with bud blast, this does not seem to affect the tree growth and the leaves. But, due to the buds being stuck together with the infection, it means that the Rhododendron will not flower.

Treatments

Not much can be done to prevent bud blast; it is a natural problem that can be dealt with by spraying the adult leafhoppers during late summer and early autumn. This keeps the leafhopper under control, but it doesn’t stop the leafhoppers flying in from another garden elsewhere.

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