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

The trees, which usually produce a dark green leaf, are being attacked by the leaf miner moth which burrows into the leaves, turning them brown and blotchy. The moth, not native to Britain, has been spreading from the south east.

Corsham town councillor Nicholas Keyworth, a warden for The Tree Council, said: “The effects are all too obvious with the telltale 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 (using light energy) 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 on to waiting traffic at the lights.

“There are many horse chestnut trees on the estate grounds that are affected.

“There is not much you can do because of the sheer scale of the problem.”

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

“For those who have horse chestnut trees at home, 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 chestnuts in Britain’s woodlands. Trees under stress from the leaf miner moth attack are more likely to succumb to a disease commonly known as ‘bleeding bark canker’ where 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 because the trunk and branches become weakened.”

There could be some good news ahead for gardeners, however.

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.