Oak decline has been spreading across the South East and northern England and was baffling scientists, according to Royal Botanic Gardens, Kew's head of arboretum Tony Kirkham. He said: "It's very worrying as it's hard to treat and related to several factors: drought, beetles and other stresses."
The Forestry Commission has stepped up research, but a representative agreed with Kirkham that the disease was unlikely to be as damaging as Dutch elm disease as some oaks are resistant. Woodland Trust operations director John Tucker said new attacks should be notified to the Forestry Commission.
Meanwhile, Defra said Phytophthora kernoviae was found for the first time in Scotland last week, following blights in England and Wales. The infection can kill trees and native heathland and seriously damage garden shrubs. A Defra representative said: "We are discussing containment and eradication."
Three outbreaks have been recorded in nurseries, one of which has been eradicated, while 46 have struck the wider environment.