Sweet chestnut blight restrictions extended across West Devon and into Cornwall

The Forestry Commission announced on Wednesday 19 August that the demarcated area for Sweet Chestnut Blight is being expanded following the discovery of further infected trees close to the boundary of the existing restricted zone.

The new restrictions are now in force and will cover West Devon District and the South East Cornwall constituency.

The Forestry Commission has been carrying out ongoing checks for the disease and has identified additional infected sites. The buffer zones around those sites extend beyond the existing restricted area, prompting the expansion.

Restrictions on the movement and sale of sweet chestnut trees and other material that could carry the disease will apply throughout the enlarged area.

The aim is to reduce the risk of the disease being spread to new locations through the movement of infected plants, timber and other material, while supporting efforts to control existing outbreaks.

Sweet Chestnut Blight is caused by the fungus Cryphonectria parasitica. It can cause serious dieback and eventually kill affected trees.

The latest developments are of particular concern because several of the recently identified outbreak sites, like an earlier finding in October 2025, show evidence of sexual sporulation.

Sexual sporulation produces airborne spores, which can travel further than spores produced by other means. This increases the risk of the disease spreading naturally beyond affected areas.

The October 2025 discovery was the first occurrence of Sweet Chestnut Blight in the UK since 2011 where sexual sporulation had been detected.

Forestry officials are now urging woodland owners, land managers and members of the public to keep a close eye on sweet chestnut trees and report any suspected cases.

Defra Chief Plant Health Officer Professor Nicola Spence said: “The risk of Sweet Chestnut Blight spreading has increased significantly in parts of the South West. Extending the demarcated area is a necessary step to help protect sweet chestnut trees.

“I would urge anyone who owns or works with sweet chestnut trees to remain vigilant and report signs of disease through TreeAlert.”

Forestry Commission Head of Plant Health Forestry Andrea Deol said: “Restricting the movement of susceptible material is one of the most effective tools we have to slow the spread of this disease.

“We would encourage the public to check their sweet chestnut trees and support the Check a Sweet Chestnut campaign. The compliance and cooperation we have already seen from forestry and trades has played a significant role in supporting our efforts so far.”

The Forestry Commission, Royal Horticultural Society and Forest Research are working together on the Check a Sweet Chestnut campaign, which encourages people to look for signs of the disease and report suspected cases.

Sweet chestnut is an important species in parts of the South West, providing timber and supporting a range of wildlife. The disease poses a particular threat to woodland where sweet chestnut forms a significant part of the tree population.

People are being asked not to move potentially infected material out of affected areas and to report suspicious symptoms rather than attempting to diagnose or treat the disease themselves.

Anyone who owns or works with sweet chestnut trees, as well as members of the public, can report suspected cases through the Forestry Commission's Tree Alert portal at - https://www.forestresearch.gov.uk/tools-and-resources/fthr/tree-alert/

A map of the expanded demarcated area is available here - https://assets.publishing.service.gov.uk/media/6a8d6d3f5a0c25165ae4642e/Sweet_chestnut_blight_20260709_SCB_Demarcated_Area_2.pdf

Further guidance on the demarcated area and restrictions is available through GOV.UK.