02
January
2017
|
11:00
Europe/Amsterdam

Hundreds of diseased or dying trees to be felled

Hundreds of trees which are diseased or have died across the city including a large number from Dutch Elm disease are to be felled this coming year.

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.

The council’s Arboricultural Service has noted about 50 dead elm trees around the city, with Kincorth, Summerhill, Rosehill, Cults, Culter, Stoneywood, and Bridge of Don particularly affected.

Aberdeen City Council Communities, Housing and Infrastructure convener Councillor Neil Cooney said: “We do not want to cut down trees but unfortunately we must, especially where there is Dutch Elm disease to try and stop it from spreading.

“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.

“Removing dead or diseased trees means there is more room for the healthy trees to grow. Our Arboricultural team will be undertaking this work over the next few months.”

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 die within three years of first signs but it may die within a season.