Horse chestnut trees are under threat in the eastern region because of the spread of a new pest.
The horse chestnut leaf miner, a moth whose larvae feed on its leaves turning them brown, is becoming increasingly widespread in the east of England.
The worst affected counties include Cambridgeshire and Northamptonshire.
The warden at Horstead Mill on the River Bure in Norfolk also alerted the Forestry Commission on Wednesday about a reoccurrence of infestation.
Although they do not cause the trees to die, the leaves they inhabit turn brown and fall prematurely.
An infestation could also hasten the demise of an already weakened tree and there is the danger of branches falling off.
Leaf miners (Cameraria ohridella) have already caused devastation to horse chestnuts in mainland Europe.
It was first recorded in Macedonia in 1985, near Lake Ohrid.
It was described as a new species of the genus Cameraria in 1986.
It rapidly spread east and west so that by 2000, it had colonised major parts of Central and Eastern Europe.
The threat to Britain has been increasing yearly.
A spokesman for the Forestry Commission said: "Transport by vehicles appears to be responsible for the sudden appearance of the moth in towns and cities in the south east and east of England."