A disease which has destroyed many thousands of Californian oaks has been found for the first time in several well-loved British tree species.
It is a fungus called sudden oak death, and till now it had been found only in UK shrubs and a tree native to the US.
But the Forestry Commission says the disease has now struck beech, horse chestnuts and holm oaks in Cornwall.
There is no known cure for the disease, which kills the trees' bark and is thought liable to affect other species.
The fungus, known as Phytophthora ramorum, has killed 80% of one oak species in the western US.
It was discovered last year in viburnum plants in British garden centres, and there have been more than 300 subsequent outbreaks in plant nurseries, and in some wild rhododendrons.