Kauri are one of the biggest and longest-living tree species in the world, reaching ages of over 1000 and perhaps even 2000 years. They have existed as a species for around 20 million years and occur naturally only in the north of New Zealand, in the Northland, Auckland and Waikato regions, and parts of the Bay of Plenty.
Ancient kauri trees like Tane Mahuta have become national icons. Just 10 years ago we discovered that these forest giants are under threat from a tiny microorganism.
Phytophthora agathidicida, the fungal-like pathogen that causes kauri dieback, was first discovered in 2009, but has probably been in New Zealand since the 1950s, if not earlier. The deadly pathogen is a water mould with a complicated life-cycle that lives in the soil. It can sense a kauri tree’s roots and swim towards them using a tail-like flagella. Once it attaches itself to the outside of a kauri root, it germinates to produce mycelia which infect the root. The tree’s fate is now sealed, as the mycelia spread through the root system and base of the tree trunk, eventually stopping the transport of nutrients and water to the canopy and killing the tree.
Kauri dieback kills kauri of all sizes and of any age – from seedlings to giants that pre-date human settlement. Seedlings may show symptoms within weeks of being infected. In juvenile trees, it may take a few years or more for symptoms to appear, and even longer in mature trees, possibly decades. There is no cure for kauri dieback, and the disease kills most if not all the kauri it infects.
Kauri dieback can be spread by just a pinhead of soil, and you can't tell by looking whether a tree is infected or not. In its inactive state the pathogen can live for many years without a kauri anywhere nearby. It can also survive for many years above ground. So, what can we do to control its spread?
Scrub footwear, spray on disinfectant and stay on track
Given the disease is primarily spread in soil, humans are regarded as the biggest carrier through contaminated soil on footwear and other gear. It’s vital that footwear and other gear is cleaned and disinfected before going near kauri, and again before leaving an area with kauri, regardless of how long it has been in storage.
Local Council track and campground closures
As the prevalence of kauri dieback is becoming better known Councils and government departments have decided to close off areas of infected kauri from public access.
As of 1 May 2018, the forested areas of the Waitākere Ranges Regional Park and several high-risk tracks in the Hunua Ranges Regional Park have been closed. The Ministry for Primary Industries has issued Controlled Area Notices (CANs) under the Biosecurity Act that apply across open tracks within the forested area of the Waitākere Ranges Regional Park and the whole of the native forested area of the Hunua Ranges regional parkland.
To follow the CANs in the Waitākere and Hunua ranges you must use hygiene stations whenever you pass them to clean and disinfect all footwear and equipment. You must not carry visible soil into the Controlled Area (including on footwear and equipment and companion animals).
In July 2018 kauri dieback was discovered on Auckland's north shore, prompting closure of several parks while a risk assessment is carried out and a management plan put in place.
A rāhui is a form of tapu restricting access to, or use of, an area or resource. A rāhui was placed over Te Waonui a Tiriwa, the forested area of the Waitākere Ranges, by mana whenua Te Kawerau a Maki in December 2017 and remains in place.
Landowners with healthy kauri
If you are a landowner with kauri in your forested areas, make sure you and your visitors have clean shoes around your kauri and avoid the roots as much as possible. Fence off individual kauri or groups of kauri from people and animals if appropriate. If you see kauri with symptoms of kauri dieback disease or want to request a tree health inspection on your land, contact 0800 NZ KAURI (0800 695 2874).
Auckland Council is taking kauri dieback very seriously and has set aside an additional $100 million for kauri dieback protection through the recent 10-year Budget process. It is working with local boards, the Department of Conservation, iwi and conservation groups as part of the Kauri Dieback Programme. Surveillance, monitroring, public education and research are all vital to develop tools to help save and protect this Taonga for future generations.
District plans are also now incorporating controls to reduce Kauri die back spreading. Recently, the Director-General of Conservation appealed decisions of Thames- Coromandel District Council (case  NZEnvC 133), when it was felt the Council did not go far enough in its plan drafting to address the problem. The Environment Court agreed, and the decision includes statements such as:
It was regrettable that efforts by agencies to combat the spread of Pa had only recently taken on any urgency as the ravaging effects of the disease on these noble trees had become more advanced and visually obvious. The disease was not waiting around, but was a terrible reality.
The court determined the regulation of Kauri die back via District Plans was not only desirable but necessary.
In addition to plan provisions, in Auckland resource consent conditions relating to Kauri die back are also now used. These include strict hygiene procedures when works occur on or around kauri trees, burying material and landfills and covering it when being relocated. If you’re doing a development, you will need to identify any kauri nearby prior to starting works, and make sure you know what your obligations are.
Want to know more?
The Kauri Dieback Programme is made up of a team of people representing tangata whenua, Department of Conservation, Ministry for Primary Industries and local government who work in environmental science, biosecurity, and mātauranga Māori (traditional Maori knowledge). You can view their website via the following link.
Disclaimer As with all our blogs, the information detailed here is general in nature and meant as a preliminary guide only. This should not be substituted for your own investigations or use of your own professional’s. Planning Plus is not liable for any errors or omissions.
Tracy is a Planner with an M.Sc. in Resource Management. Tracy has worked assisting Senior Planners with the preparation and lodgement of resource consent applications, as well as planning. She also provided support in client liaison, contractor engagement and general communications.