About 50 elm trees on Takarunga/Mt Victoria, in Devonport, have been removed after they were found to be infected with Dutch elm disease.

Arborists removed the trees on Tuesday, using a helicopter, in order to prevent the disease from spreading further.

The trees were removed from the northern boundary, and were be lifted to the summit for ease of processing. For safety reasons Takarunga was closed to the public on Tuesday.

Auckland Council senior arboriculture specialist Simon Cook said removal was the only option.

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"There is no way to effectively treat Dutch elm disease or to cure an infected tree. The disease can spread quickly and it is nearly always fatal.

"In this instance, the 50 or so elm trees of varying size and age are all connected through an interlinked root system through which the disease will easily spread, so all of them must be removed to ensure the disease is eradicated from this site."

Dutch elm disease was an extremely virulent fungus that lived in the bark of an infected elm and causes it to wilt and die.

It was transferred from tree to tree through root grafting or via the elm bark beetle. The fungus only affected elms and an infected tree could not be cured.

Dutch elm disease is an extremely virulent fungus that lives in the bark of an infected elm tree and causes it to wilt and die. Photo / Brett Phibbs
Dutch elm disease is an extremely virulent fungus that lives in the bark of an infected elm tree and causes it to wilt and die. Photo / Brett Phibbs

In New Zealand, Dutch elm disease was contained to Auckland, so every precaution was taken to ensure it did not spread further afield.

Cook said the felled trees would be immediately mulched on-site, which destroyed the fungus and any elm bark beetles that could be present, allowing material to be safely transported without the risk of further spread.

The Tūpuna Maunga Authority would rehabilitate the site of the removed trees with grass cover and in time will replant appropriate native trees.

Operations manager Nick Turoa said the trees were removed using a helicopter due to the limited access, and to limit disturbance of the sensitive sites.

The trees were removed in sections weighing between 600 and 1200kg.

In March 2018 the authority also received a similar notice to remove diseased elms from Ōhinerau/Mt Hobson.

This latest discovery was a timely reminder for all Aucklanders to check elms on their properties for signs of the disease, Cook said.

Elms were deciduous trees distinguished by their large leaves, which feature serrated edges, symmetrical veins, and an asymmetrical base.

Signs of Dutch elm disease include wilting, curling or yellowing of leaves or dying or dead branches on elm trees.

Cook said people should not attempt to remove diseased trees themselves as incorrect processing of trees could spread the disease. People should instead call Auckland Council on 09 301 0101.

"Do not be tempted to use the timber for firewood. Diseased wood must not be stored, and it is illegal to move diseased wood within or out of the Auckland region."