An outbreak of ash dieback (Chalara fraxinea) has been confirmed in the National Forest near Ashby-de-la-Zouch, Leicestershire.
The Forestry Commission has identified the disease on 17-year-old and five-year-old trees within the 500 sq km site, where planting of native broadleaf trees began in the early 1990s, and is ongoing.
Catherine Graham-Harrison, chair of the National Forest Company which manages the site, said: "Ash is a significant tree in the Forest, probably around 15 to 20 per cent of all the trees we have, but in the National Forest we have always planted mixed-species woodlands. Over time the biggest visual impact is likely to be from losing mature hedgerow ash trees, but not whole woodlands.
"It is hoped that in the future we can again plant ash trees once disease-resistant trees have been found and grown to seedling stage."
Chief Plant Health Officer Martin Ward said: "We will be investigating this new case closely."
Leicestershire is now the 14th county in which the lethal tree disease has been confirmed. The first case in Dorset was also uncovered earlier this month.