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Auckland on watch following Dutch elm disease outbreak

More than 200 elm trees on the privately-owned Kingseat site near Drury have become infected with Dutch elm disease, making it the largest outbreak of the disease since its discovery in New Zealand in 1989. Source: Voxy
Dutch elm disease is spreading further south, with diseased trees recently destroyed near Appleby and Drury Hills Roads, Drury. Further outbreaks have been identified in South Auckland including: Rogers Park, Bucklands Beach; Lloyd Elsmore Park, Pakuranga; and the Manukau Memorial Gardens, Mangere. Diseased trees were identified as the result of regular annual monitoring and reports from members of the public and contractors.
Auckland Council Arboriculture and Landscape Advisor, Simon Cook, says they assisted the property owner and manager at Kingseat to ensure the elms were safely cleared.
“Kingseat is a historic character site with elms initially planted in the 1930s. It’s a shame that they will be losing such a significant number of trees. However, this demonstrates just how devastating the disease really is.”
Dutch elm disease is usually spread by the bark beetle (Scolytus multistriatus) carrying fungal spores from tree to tree, or through the transfer of diseased tree materials, but can also spread directly through root grafting between neighbouring trees. All affected trees will be treated and removed safely and all equipment used will be disinfected to ensure the disease does not spread.
Mr Cook says: “Given the speed at which Dutch elm disease can spread, and the fact that it’s nearly always fatal for affected trees, we’re taking every precaution to ensure we remove the trees safely and contain the threat withinAuckland.”
The disease has caused a huge loss to the landscape in those areas affected by Dutch elm disease over the last season. If the disease moves into the Waikato, where elms are prevalent in urban and rural zones, then this landscape will also be depleted of these large and significant specimen trees.
“I call on Aucklanders to check elm trees on their property, especially those around the Bombay Hills and Pukekohe, and report any suspected cases of Dutch elm disease they see in public places. New cases will become evident during spring, with elm either not coming into leaf or wilting rapidly after bud burst.
“It is critical that elm wood is not carried outside Auckland, especially as logs or firewood. Elm material that is diseased will often harbour or attract bark beetles – it must be buried, mulched or burnt.”
Elms are deciduous northern hemisphere trees distinguished by their large leaves, which feature serrated edges, symmetrical veins, and an asymmetrical base. Residents are asked to watch for signs of wilting, curling, or yellowing leaves; or dying or dead branches and trees.
Dutch elm disease was first discovered in Myers Park, Auckland in 1989. Following an information campaign and ongoing monitoring, it has been contained within the Auckland region. The most recent outbreak was in October last year which saw 50 elm trees in Whitford removed to contain the disease.
Controls prohibit the movement of elm material in and out of the Auckland area between the Bombay Hills and Albany.
Storage of elm wood is also prohibited under the Biosecurity Act 1993. Elms cannot be brought into Auckland nor sold at Auckland nurseries.
For more information on Dutch elm disease, please visit www.aucklandcouncil.govt.nz or call 09 301 0101.