For the past 16 months, Auckland Council has been delivering phosphite to infected kauri in the Waitākere Ranges.
The first large scale application of phosphite as a treatment for kauri dieback was delivered in early 2018 with over 3700 kauri treated in the catchment of the Maungaroa Ridge area of the ranges.
Another long-term field trial in the Piha catchment has seen a further 7019 trees injected over the last year.
While phosphite does not represent a ‘cure’ for kauri dieback, it does offer protection to individual kauri trees to fight back. Phosphite has been used since the 1970s to protect crops like avocado, pineapple and cocoa against diseases but only recently tested on kauri.
The initial trials have helped deliver best practice in the large-scale use of the chemical in treating kauri in a forest setting and will enable the long-term impact monitoring of the trees with the symptoms, to better understand the potential of phosphite as a treatment in a variety of situations.
Once more is known on the effectiveness of the injection, treatment procedures may be updated.