Dozens of diseased or dying trees suffered from Dutch Elm disease have been felled across the city since the start of a programme this year.
About 60 dead elms have been taken down by Aberdeen City Council’s arboricultural service to date and are included in the hundreds of trees which are due to be felled.
There are about 400 of the 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 trees still left are in streets which have up to 10 dead or dying trees on them so road closures will be necessary in some areas to safely cut down these trees. Road closures will be happening in Willowbank Road, Westburn Drive, Rosehill Drive, Hilton Street and Stronsay Road for this purpose.
The arboricultural service had noted Kincorth, Summerhill, Rosehill, Cults, Culter, Stoneywood, and Bridge of Don areas particularly affected. It was initially thought there were about 50 diseased Dutch Elm trees around the city but unfortunately more were found.
Aberdeen City Council Communities, Housing and Infrastructure convener Councillor Yvonne Allan said: “Our arboricultural team has made excellent progress at felling the dying elm trees as we must do what we can to try and stop the disease from spreading.
“We don’t want to cut down trees but unfortunately we must as the work not only helps to prevent the spread of the disease, but it also means there’s more room for the healthy trees to grow..
“Our priority is to have safe and healthy trees for residents and visitors to enjoy in all parts of the city as part of our beautiful and vibrant green spaces.”
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.
The first 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 shepherds 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 signs but it may die within a season.