Thousands of horse chestnut trees across Wiltshire are at risk of dying because of a disease that is spreading throughout the county.

The tree leaves are being attacked by the leaf miner moth which burrows into them, turning them brown and blotchy.

The moth, which is not native to Britain, has been slowly spreading in a westerly direction from the south east and has has now reached Wiltshire.

Corsham town councillor Nicholas Keyworth, a warden for The Tree Council, said: “The effects are all too obvious with the tell-tale marks on the leaves of these majestic trees, causing them to turn brown and wither.

“Over time this will seriously weaken the tree by preventing it photosynthesising effectively, so the tree starves to death.”

Weakened trees alongside roads could become dangerous if their branches fall onto passing vehicles.

Chris Waltho, Corsham Court estate manager, said: “Some of the trees along the Cross Keys Road have been cut back because the branches could fall onto traffic waiting at the lights.

“There are many horse chestnut trees on the estate that are affected. There is not much you can do because of the sheer scale of the problem.”

Almost all the horse chestnut trees in Trowbridge Park are in the early stages of attack from the moth.

Chris Sorensen, Forestry Commission officer for the 4,500-acre Savernake Forest near Marlborough, said: “There are quite a few that are affected here at the forest but the problem is limited thankfully because the horse chestnut is not generally a forest tree.

“For those who have horse chestnut trees at home though I believe the advice is that you should rake up dead leaves and bin them, that way you at least kill off that year’s offspring.”

It is estimated that there are around 500,000 horse chestnut trees in Britain’s woodlands.

Trees under stress from the moth are more likely to succumb to a disease known as ‘bleeding bark canker’ in which the trunk and branches ooze a black liquid.

Mr Waltho added: “Some trees can survive bleeding canker, others die, but many have to be felled for public safety.”

There could be some good news ahead, however, for gardeners. It is thought that a parasitic wasp, which has become increasingly present in Britain, is the leaf miner’s natural predator and could help to eradicate the problem because it feeds off the larvae produced on an infested tree.