Japanese larch-killing disease Phytophthora ramorum has spread to a third region in England.
The discovery in woodland between Burnley and Clitheroe, Lancashire comes just weeks after the disease was confirmed in the Peak District.
The Forestry Commission said investigations were continuing into other suspected sites in north-west England but it believed there was a “high probability” that more outbreaks would be confirmed in the region.
It said the finding, coupled with another discovery on the Isle of Mull, showed the threat posed by the disease was still serious.
However, the numbers of Japanese larch found to be infected this year has decreased substantially to 227ha from 876ha a year ago.
“The worst case scenario would have been to have found the same number, or even more, trees infected by ramorum disease this year as last year,” said the commission.
“Whilst it is worrying that we will have to fell a large number of infected trees again this year, it would seem that our decision to swiftly fell infected trees last year has played a key role so far in managing this major outbreak,” it said.
Japanese larch is a commercial timber species in demand for outdoor uses.
