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Dutch elm disease found at Ōhinerau / Mt Hobson

Published: 19 March 2018

About 18 elm trees on Ōhinerau / Mt Hobson have become infected with Dutch elm disease and are being removed as a biosecurity measure by Auckland Council under the direction of the Tūpuna Maunga Authority.

Arborists will remove the trees on the north-eastern side of the maunga using a helicopter on Tuesday 27 and Wednesday 28 March. For safety reasons, all entrances to Ōhinerau / Mt Hobson will be closed to the public over these days.

Paul Majurey, Chair of the Tūpuna Maunga Authority, explains that leaving the trees in place is not an option.

“The removal of diseased trees is a requirement under the Biosecurity Act 1993. The Tūpuna Maunga Authority also supports the removal as an important step towards minimising the spread of Dutch elm disease to neighbouring suburbs,” says Majurey.

The work will be overseen by Auckland Council arboriculture specialists and carried out by Treescape, who are experienced in complex tree removals using helicopters and have an excellent health and safety record. Treescape will also use machinery to mulch the trees on-site. Mulching destroys the disease, which affects the bark of the tree.

As an added precaution, it is essential that people do not visit the maunga over the two days that work is taking place. Assuming no delays are caused by weather, Ōhinerau will be open to the public again on Thursday 29 March.

Several diseased elm trees were removed from Ōhinerau / Mt Hobson in 2015 and Auckland Council recently found Dutch elm disease on elm trees in the city centre. The findings are a reminder for all Aucklanders to check elm trees on their properties for signs of the disease.

How to spot it

Dutch elm disease is an extremely virulent fungal disease that causes infested elm trees to wilt and die. It is transferred via the elm bark beetle carrying fungal spores from tree to tree but can also be spread through root grafting. The disease can spread quickly and is nearly always fatal for the affected tree.

Elms are deciduous trees distinguished by their large leaves, which feature serrated edges, symmetrical veins, and an asymmetric base. Signs of Dutch elm disease include wilting, curling or yellowing of leaves or dying or dead branches.

In New Zealand, Dutch elm disease is currently found only in Auckland.

How to control it

Wood from diseased trees must be mulched or destroyed immediately on-site to prevent the disease spreading. Infected elm wood must not be stored for firewood or used for building or other woodwork.

No material from an infected elm tree can be transported within or outside of the Auckland region between the Bombay Hills and Albany. 

If you believe an elm tree on your property may be infected with Dutch elm disease, call Auckland Council immediately on 09 301 0101.

Read more: Environment Ōrākei

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