Dozens of trees across city to be felled due to Dutch Elm disease

28 March 2019

Several dozen diseased or dying trees suffering from Dutch Elm disease are to be felled across Aberdeen this year.

The City Council’s arboricultural service started a programme two years ago cutting down trees which have been affected by the deadly condition.

Dutch elm disease is one of the most serious tree diseases in the world which has killed more than 60 million British elms in two epidemics and continues to spread today.

About 70 trees have been felled across the city since the start of the programme and it is estimated there are about 400 diseased or dying trees, which are mainly beside roads but some are in parks, gardens and play areas. Aberdeen City Council has about 100,000 trees and 400 hectares of woodland.

Some of the diseased or dying trees are in streets which will require road closures for removal, and they include Rosehill Drive, Hilton Street, Cattofield Place, Westburn Drive, and Willowbank Road.

The 70 trees which have been removed so far were in high-risk areas, and the arboricultural service has also started to tackle woodland areas such as Danestone Country Park.

Aberdeen City Council operational delivery convener Councillor John Wheeler 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% to 40% of elm trees, and 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 O. novo-ulmi is spread by elm bark beetles and it infects all of Britain’s elm species.

Dutch Elm disease continuing to push northwards, 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, allowing the larger elm bark beetle - Scolytus scolytus - to expand beyond its previous northern territorial limits.

The elm bark beetle spreads the pathogens through a fungus which disrupts the tree’s water conducting system. Symptoms normally appear in mid-summer with leaves turning yellow and hang onto 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.

The tree will normally die within three to five years of first sign but it may die within a season.