Hundreds of trees could be felled across the city of Aberdeen due to an outbreak of deadly Dutch elm disease.

Aberdeen City Council’s arboricultural service has already felled 70 infected trees from “high-risk areas” and woodlands including Danestone Country Park.

Officials estimate there are still around 400 diseased or dying trees at roadsides, as well as in parks, gardens and play areas.

Plans are already in place for “several dozen” to be felled this year, with some streets required to be closed for work to take place.

Aberdeen City Council has about 100,000 trees and 400 hectares of woodland. Dutch elm disease is one of the most serious tree diseases, and currently there is no cure.

Spores of the deadly fungus hitch-hike on the bodies of tiny elm bark beetles, which carry the disease from tree to tree, although the insect needs a temperature of at least 20°C to fly.

The disease has already killed more than 60 million British elms in two epidemics and continues to spread today.

Aberdeen City Council started a programme two years ago cutting down affected trees in a bid to prevent the spread of the disease.

Councillor John Wheeler, the local authority’s operational delivery convener, said: “We do not want to cut down trees, especially if they’re large mature specimens, but unfortunately we must as there is no cure for Dutch elm disease.

“We need to do what we can to help to prevent the spread of the disease, which means cutting down some trees which may look healthy but have the first signs, and it’s better to remove them before the condition can migrate and devastate the elms in an entire community.

“We have beautiful woodland, parks and other green areas all over Aberdeen and we want to continue to have safe and healthy trees for residents and visitors to continue to enjoy.”

The first Dutch elm epidemic was caused by fungus Ophiostoma ulmi from the 1920s onwards when it killed 10 per cent to 40% of elm trees.

The second and ongoing epidemic is caused by the more aggressive and related fungus O. novo-ulmi, which was accidentally introduced into Britain in the 1960s and first recognised in the 1970s.

The aggressive fungus infects all of Britain’s elm species. Dutch elm disease is continuing to push north, particularly on the east-coast north of Aberdeen, probably due to O. novo-ulmi having a lower optimum temperature for growth than O. ulmi, and the much greater epidemic momentum that O. novo-ulmi has generated.

This allows the larger elm bark beetle Scolytus scolytus to expand beyond its previous northern territorial limits.

Symptoms normally appear in midsummer with leaves turning yellow and hanging on to the stem, which then turn brown and fall early.

This normally starts at the tips of branches which can bend to resemble a shepherd’s crook.

The affected stems die back from the tip and have a distinctive brown stain in cross section just below the bark. Affected trees normally die within three to five years of first sign but may perish within a season.