The Royal Horticultural Society (RHS) and Coventry University are calling on the public to spot sweet chestnuts on their daily stroll as they launch a new citizen science project to help protect the at-risk tree for the future.
Found in woods and parks throughout the UK, the iconic sweet chestnut (Castanea sativa) with its attractive, deeply-grooved bark, distinctively jagged-edged leaves and clusters of edible nuts is an important source of food for wildlife – including bees, pollinators and squirrels - and can live for up to 700 years when healthy. Thought to have been introduced by the Romans, the trees are now under threat from newly arrived oriental chestnut gall wasp (Dryocosmus kuriphilus) which disfigure and weaken the tree, with the RHS Science team eager to map the non-native insect and trees in varying states of health.
Most sweet chestnut trees can be found in the south of England, particularly in Kent and Surrey, but have been found to reach farther north than the Cairngorms. Beyond this very little is known about their distribution in the UK, making it difficult to fully understand the threat to UK gardens and green spaces and provide effective protection.
First discovered in the UK in 2015, the oriental chestnut gall wasp spreads through flight and likely entered the UK through plant imports. The wasp larvae cause abnormal growths, known as galls, on the buds and leaves of the sweet chestnut tree. In high numbers these galls can weaken the host tree, making it more vulnerable to other pests and diseases, particularly sweet chestnut blight.