Public appeal for the sweet chestnut

The Royal Horticultural Society (RHS) is calling for the public to urgently monitor sweet chestnut trees during National Tree Week to help safeguard its future.

Sweet chestnut
Photo by Jez Timms on Unsplash

Volunteers are being asked to look for signs of disease, the oriental chestnut gall wasp or if the tree is healthy and then report their observations.

Unfortunately, sweet chestnut trees (Castanea sativa) – one of the country’s most iconic trees, found alongside roads, in parks and woods – are facing a growing threat from two devastating problems: the oriental chestnut gall wasp (OCGW) and a fungus, chestnut blight. To help tackle their plight, the RHS, Defra, Animal and Plant Health Authority and Forest Research have joined together to call for the public to check a sweet chestnut tree where they live and to report any signs of disease or where the trees are healthy.

As sweet chestnuts drop their leaves at this time of year it is a particularly good time to look for signs of disease. Getting involved in the project is easy and all records must be submitted by the end of National Tree Week. Using the information on the RHS website volunteers can simply identify a sweet chestnut tree; look for signs of sweet chestnut blight or oriental chestnut gall wasp; take photos of the tree and go to Tree Alert, the official government reporting tool for tree health, and fill in a report.

Signs to look out for include distorted leaves or buds with swellings (galls), a sparse tree crown and sunken, cracking or discoloured bark. Full details on the RHS website.

The RHS urge that it is just as important to report healthy trees, showing no signs or symptoms of OCGW or chestnut blight. Together the reports will inform Forest Research scientists of where affected trees are, as well as the proportion being affected. The data will be used to create a national map of the health of sweet chestnut trees across Britain, which will help target future conservation efforts and help to protect the sweet chestnut tree.

The threats posed by chestnut gall wasp and chestnut blight are significant. The OCGW lays its eggs inside the tree’s buds, causing abnormal growths, known as galls, which can stunt the tree’s growth and reduce its ability to produce nuts. Chestnut blight is a fungal disease that causes cankers on the tree’s bark and can eventually kill the tree. Both diseases are spreading across Europe and pose a major threat to the health of sweet chestnut trees.

Nicola Spence, UK Chief Plant Health Officer, said: “Sweet chestnut trees – like many other plant and tree species – are increasingly vulnerable to pests and diseases. Encouraging the public to be good plant health citizens and report disease sightings is absolutely crucial if we are to minimise the risk to our cherished treescapes.”

Ruth Chitty, RHS Plant Pathologist, added: “The Check a Sweet Chestnut project is a vital tool in the fight to protect tree health and empowers members of the public to get involved in conservation efforts. These pests and diseases pose a huge threat to Britain’s sweet chestnut trees, without which our landscapes would look very different, but by working together to record and monitor these trees we are helping safeguard them for future generations to enjoy.”

The deadline to submit information for the project is during National Tree Week, which runs from 26 November – 4 December 2023.