Kauri dieback is a pest issue that is increasingly affecting kauri forests A water and soilborne pathogen Phytophthora taxon Agathis (PTA) has been identified as a causal agent of kauri dieback at multiple locations particularly within Auckland and Northland In 2008 a passive surveillance and adaptive management programme was initiated to manage the disease across the natural range of kauri Surveys were initially undertaken to determine the distribution and rate of spread of kauri dieback on private land in the Auckland region Methods to evaluate and monitor overall tree health disease symptoms and other potential contributing factors were developed Diagnostic sampling was undertaken to isolate and identify pathogens associated with kauri dieback Along with PTA other Phytophthora species and environmental stress were frequently associated with symptoms at over 400 properties inspected Further management is now required to develop control tools and mitigate further spread

In Aotearoa/New Zealand, the soilborne pathogen Phytophthora agathidicida threatens the survival of the iconic kauri, and the ecosystem it supports. In 2011, a surveillance project to identify areas of kauri dieback caused by Phytophthora agathidicida within the Waitākere Ranges Regional Park (WRRP) highlighted the potential impact of the pathogen. A repeat of the surveillance in 2015/16 identified that approximately a quarter of the kauri area within the Regional Park was infected or possibly infected, an increase from previous surveys. The surveillance program mapped 344 distinct kauri areas and showed that 33.4% of the total kauri areas were affected or potentially affected by kauri dieback and over half (58.3%) of the substantial kauri areas (above 5 ha in size) were showing symptoms of kauri dieback. Proximity analysis showed 71% of kauri dieback zones to be within 50 m of the track network. Spatial analysis showed significantly higher proportions of disease presence along the track network compared to randomly generated theoretical track networks. Results suggest that human interaction is assisting the transfer of Phytophthora agathidicida within the area. The surveillance helped trigger the declaration of a cultural ban (rāhui) on recreational access. Te Kawerau ā Maki, the iwi of the area, placed a rāhui over the kauri forest eco-system of the Waitākere Forest (Te Wao Nui o Tiriwa) in December 2017. The purpose of the rāhui was to help prevent the anthropogenic spread of kauri dieback, to provide time for investment to be made into a degraded forest infrastructure and for research to be undertaken, and to help protect and support forest health (a concept encapsulated by the term mauri). Managing the spread and impact of the pathogen remains an urgent priority for this foundation species in the face of increasing pressures for recreational access. Complimentary quantitative and qualitative research programs into track utilization and ecologically sensitive design, collection of whakapapa seed from healthy and dying trees, and remedial phosphite treatments are part of the cross-cultural and community-enabled biosecurity initiatives to Kia Toitu He Kauri “Keep Kauri Standing”.

The causal agent of kauri dieback Phytophthora taxon Agathis (PTA) poses a significant threat to kauri (Agathis australis) in northern New Zealand Groundbased field surveys have previously confirmed PTA presence at several locations across Auckland and Northland However ground surveys are limited to areas adjacent to tracks because of difficulty and cost associated with offtrack access in steep terrain along with concern about furthering spread of PTA A methodology for aerial photographic surveillance of kauri dieback was developed and implemented in Wait257;kere Ranges Hunua Ranges and adjacent forest areas Using recently developed GPS technology photographs were embedded with position data so unhealthy trees were easily located later for groundtruthing Aerial survey was found to be a time and costeffective method for surveying large inaccessible areas of forest for kauri dieback The methodology would also be applicable for detection of visible disease or damage symptoms in other canopy tree species