HUNDREDS of horse chestnut trees across Oxfordshire are under threat in what looks to be the worst case of tree blight since Dutch elm disease 30 years ago.

The trees have been hit by the arrival in the region of the horse chestnut leaf-mining moth.

The infestation has left trees looking in poor health, with leaves withering long before the onset of autumn.

And there is bad news for the county's school children with the blight significantly reducing the number of conkers produced.

It is still unclear what will be the long-term impact of the leafing mining moths, first established in the UK in the borough of Wimbledon four years ago.

At the moment there is nothing to control the month or stop its spread, say experts.

Heavy infestation results in leaves turning brown and dropping with the tree taking on an early autumnal appearance.

Council tree officer Michael Lear said although there was no firm evidence to suggest that horse chestnuts will die, the repeated loss of three month growth and repeated defoliation was bound to seriously undermine tree health.

To make matters worse it seems that some local horse chestnuts are also being ravaged by a bleeding canker.

The arrival of the moth in Oxfordshire has now been reported to the Forestry Commission.

Tree expert Kevin Calidcott said: "The advice is that tree owners should not rush out and fell their horse chestnut trees because of the problem."

The horse chestnut leaf mining moth was first observed in Macedonia in northern Greece in the late 1970s and quickly spread throughout central and eastern Europe.

Up to 700 leaf mines have been recorded on a single leaf under favourable conditions.

A spokesman for Forest Research said: "The moth has spread to many parts of southeast England and now as far as west as Oxfordshire and north into the Midlands.

"Collecting up and disposing of the leaves in autumn is a way of trying to keep the trees looking good for longer.

"These leaves contain the over-wintering stage of the moth, the Pupae, and their removal can delay the onset of the damage to the leaves the following spring."

Leaves should be burned or if composted, covered with a 10cm layer of soil.

Forestry Research says it is now trying to find ways of using natural enemies and parasites to bring the moth numbers under control. But a spokesman added: "This could take some time."