Treating Taonga Trees in the Cascades

Kauri Rescue and Te Kawerau ā Maki spent all of May working together on public land for the first time. We undertook a large tree treatment trial, under the guidance of our project leader and Plant & Food Research scientist Dr Ian Horner, to test a range of concentrations and doses of phosphite on trees over 200cm circumference with kauri dieback in the Te Piringa Track area of the Cascades, part of the Waitākere Ranges Regional Park. This work was funded by Auckland Council, which is enabling Te Kawerau ā Maki as mana whenua to improve kauri health within their rohe working in collaboration with Kauri Rescue.

It was a huge privilege to be trusted to treat these incredibly important taonga trees and it was such a pleasure to work in that diverse and special ecosystem alongside mana whenua. We are actually still pinching ourselves that we were able to do this mahi.

Thanks to ARK in the Park staff Sam Lincoln and Eduardo Colley and our hard working Ambassadors Guenter Niersbach and Rebecca O’Cleirigh, together with Te Kawerau ā Maki’s Jocelin Friend and Mihi McMahon working alongside Kauri Rescue staff Mels Barton and Avril Dirga we were able to GPS locate, assess the health and treat 59 of the largest trees, some over 700cm in circumference. Ian Horner also did a more detailed health assessment of 37 of the treated trees.

Whilst this represents the tip of the iceberg of the infected kauri in the Cascades, it will provide valuable insights into the best treatment doses for these very large trees for future applications.

Kauri Rescue and Te Kawerau ā Maki would like to continue this collaborative work to help protect more of these taonga (treasure) trees in this very special area of the Regional Park that was never logged and formed the core of the Auckland Centennial Memorial Park. Treating the trees less than 200cm circumference in the same area will provide additional protection for the largest trees and reduce the amount of pathogen being produced in this special ecosystem.

New funding from Foundation North

Foundation North have funded a small project to help Kauri Rescue support our collaboration with Te Roroa (mana whenua for Waipoua Forest), and to help build relationships with other iwi/hapū in Northland. We’re looking forward to reaching out.

International Union of Forest Research Organisations (IUFRO) Phytophthora Conference 2024

In September in Paihia, Bay of Islands, the world’s leading Phytophthora scientists will gather at their annual international conference to present to each other their latest research. As hosts there will be a big emphasis on kauri dieback and Dr Ian Horner will be presenting a number of papers, including one about the Kauri Rescue project and our citizen science approach. Ian and Mels will both be attending the conference and look forward to hearing about the ways in which other Phytophthora are managed around the world, as well as the latest science from here in Aotearoa / New Zealand.

Registrations are open now so if you’d like to attend you can find all the details here.

Treatment Tools Evaluation Report and Online Hui

The Biological Heritage Science Challenge Saving Our Iconic trees / Ngā Rākau Taketake funded Kauri Rescue to undertake a three year project to follow the fate of at least 500 trees previously treated with phosphite. The main aims were to assess the effectiveness of phosphite for treatment of kauri dieback, and to assess the accuracy of the participants in implementing the treatment/monitoring protocols and collecting the data. 

This work is now complete, thanks to the huge efforts of many of our participant landowners and volunteer ambassadors for collecting the health reassessment data that has enabled us to do the analysis.

The results have shown that:

• There is evidence that phosphite at either of the concentrations offered, injected around the trunk with a high or low dose, reduces the activity of lesion symptoms caused by Phytophthora agathidicida. The duration of the effect is not as long in the low dose treatments, with an increase in the number of active lesions noted after 5 or 6 years. 
• Participant landowners were biassed in selecting treatments and untreated trees, giving higher doses of phosphite to sicker trees and not treating healthy or asymptomatic trees. 
• There were multiple obvious errors in the original data, especially that collected or entered by citizen scientists, and many trees were discarded from the analysis in a data cleaning exercise. The citizen scientist data used for this investigation is therefore highly sanitised. 
• Our processes, manuals and training videos have been significantly simplified and improved, and support, training and guidance of participants increased as a result of the errors and inconsistencies identified in the way citizen scientists collected and recorded the data.
• The willingness of landowners to collect annual or biennial tree health reassessment data waned significantly over time.

You can read the full report here.

Kauri Rescue’s science lead Dr Ian Horner will be presenting the results of this work in an online webinar on Wednesday 28 August at 7pm. If you’d like to attend please register here.

Huge thanks to all our landowners and ambassadors who have contributed to the enormous data set analysed for this project. The entire pool of participants (109) and trees (3163) at the start of the project were assessed for potential inclusion. Many of these trees were assessed multiple times by our citizen science team over the course of the project. This work has enabled us to learn a lot about how kauri are responding to the phosphite treatments applied.

Ngā Rākau Taketake Research Programme Ends

In 2018 and 2019 the Government announced an extra $34.5 million funding for research into kauri dieback ($29.5m) and myrtle rust ($5m). They chose the BioHeritage National Science Challenge to administer this extra support because of their collaborative and inclusive approach to achieving research outcomes and impact.

A huge amount of research work has been undertaken during the 5 year programme, but the Ngā Rākau Taketake research ended on 31 March 2024. You can check out the inventory of research outputs and resources in the BioHeritage Data Depository.

One of the final news articles produced was about Kauri Rescue, as Ngā Rākau Taketake was our initial funder and has supported our work ever since. We are immensely grateful to the whole team for believing in our citizen science concept and enabling us to launch our project.