THE public is being asked to help track a disease which has already killed thousands of trees.

The phytophthora fungus has wiped out around 18,000 of the 580,000 alder trees in England and Wales over the last few years.

Now the Environment Agency wants people to report any sightings of dead or dying alder trees - commonly found on river banks - in a bid to find discover more about the fungus.

The Environment Agency and the Forestry Commission have been studying the problem nationally for the last three years.

Until 1993 phytophthora had never been reported in alders, although a similar form was known to affect other trees.

Diseased trees have been found across the North West, including Lymm in Cheshire, Garstang in Lancashire and Brough and Bewcastle in Cumbria. Paul Green, the Environment Agency's senior conservation scientist in the North West, said alders were important for wildlife and their roots helped stabilise riverbanks.

"This disease could have a major impact on the river landscape," he warned.

"In the North West we still don't know enough about where it is occurring, and we are therefore very keen to hear of any sightings."

From a distance, diseased alders are noticeable in mid to late summer because the leaves are abnormally small, yellow and sparse. They frequently fall prematurely, leaving the trees bare.

On closer inspection, the lower portion of the tree trunk is often marked with tarry or rusty patches, indicating that the bark is dead.

A leaflet with advice for landowners on tree management, is available from Environment Agency offices.

Anyone who spots diseased trees should call the Environment Agency on 0645 333111 during office hours and ask for conservation.

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