Surveillance methods to determine tree health, distribution of kauri dieback disease and associated pathogens

Abstract

Kauri dieback is a pest issue that is increasingly affecting kauri forests. A water and soilborne pathogen, Phytophthora taxon Agathis (PTA), has been identiied 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. © 2013 New Zealand Plant Protection Society.