Pest or disease?

Latin name:
Dryocosmus kuriphilus

Host trees:
Sweet chestnut trees

Present in the UK?
Yes, in and around London and south east England

Tree Alert required?

In 2015 the first UK finding of Oriental chestnut gall wasp was recorded in Kent. 

The second finding of this pest was from an Observatree volunteer in Greater London, demonstrating that the pest had already spread from its potential introduction site or had been introduced twice. It is native to Asia and is a pest of sweet chestnut trees. It has since spread and is now found in and around London and the south east.

This is the only known species to produce galls on sweet chestnut trees, so galls are a good symptom to look out for. These are circular growths that can be on the buds, leaves or leaf stalks. If a tree has a lot of galls it can weaken it, making it more susceptible to other pests and diseases, such as sweet chestnut blight which can be fatal. For more information on this pest please see the resources below.