The Forestry Commission announced today, 19 August 2026, an extension to the demarcated area for Sweet Chestnut Blight in Devon, now including a small part of Cornwall. This decision follows further findings of the disease close to the existing restricted zone boundary.
The expanded area, which will come into force on Wednesday 26 August, will encompass West Devon District and the South East Cornwall constituency. This extension is a result of continued surveillance work that confirmed additional infected sites, with buffer zones extending beyond the current area boundary.
Trading restrictions on sweet chestnut trees and other susceptible material will be enforced across the enlarged area. This measure aims to prevent the further spread of the fungal disease through the movement of infected plants and materials, supporting disease management efforts.
A Sweet Chestnut Blight finding in October 2025 marked the first instance of the disease with sexual sporulation present since 2011. The additional outbreak sites identified through recent surveillance also show evidence of sexual sporulation, indicating an increased production of airborne spores. This significantly raises the risk of the disease spreading further afield.
Professor Nicola Spence, Defra Chief Plant Health Officer, stated that the risk of Sweet Chestnut Blight spreading has significantly increased in parts of the South West. She urged anyone who owns or works with sweet chestnut trees to remain vigilant and report signs of disease through TreeAlert. Andrea Deol, Forestry Commission Head of Plant Health Forestry, emphasised that restricting the movement of susceptible material is a key tool to slow the disease's spread.