Surveillance and management of kauri dieback - Dr Nick Waipara

Kauri Dieback Symposium 30 November 2013
Talk 3 of 13

Kauri dieback caused by Phytophthora 'taxon Agathis' (PTA), has been prioritised as an emerging biosecurity threat to kauri (Agathis australis) and the kauri forest ecosystem of northern New Zealand. PTA is a water and soilborne pathogen that infects kauri through its roots. Post-infection symptoms of kauri dieback include; root rot, a collar rot resulting in large basal trunk lesions, canopy defoliation and death. All size and age classes of kauri have been confirmed as being susceptible to infection and death. In 2008, PTA was declared an unwanted organism and a national kauri dieback management programme was initiated. Standardised survey methods were developed to undertake national surveillance of prioritised forests to determine the distribution of PTA in New Zealand. Survey sites were prioritised to kauri areas with; high conservation value; containing culturally significant or iconic trees, or representing the natural geographic range of kauri. A risk assessment to determine current vectors and potential historic pathways of disease spread led to surveys and sampling also being undertaken in rural fragments containing remnant kauri, historic kauri plantations and nurseries, and at sites of high soil disturbance. Detection of PTA from soil and tissue was achieved by the development of specific baiting and isolation methods. Both aerial and ground based surveys were undertaken to locate symptomatic trees as was a passive surveillance programme whereby the public reported symptomatic trees for inspection and diagnosis. A management programme to contain disease spread and protect healthy kauri has also been implemented across kauri land.