Biosecurity NZ investigates new fungus in Northland

DATE 24 March 2006

Biosecurity New Zealand investigates new fungus in Northland.

Biosecurity New Zealand is investigating the occurrence of a new fungus in Northland that has been found in one orchard and confirmed present in a sample collected from Trounson Kauri Park. The fungus was detected as a result of a MAF Operational Research funded project to determine the species of Phytophthora present in New Zealand using new DNA technology. This work was undertaken by collaborative project between Landcare Research, ENSIS and HortResearch.

Senior advisor surveillance and incursion response (plants) George Gill, says initial investigations are centred on the plant pathogen Phytophthora kernoviae, which is an unwanted organism under the Biosecurity Act. This particular organism, is an invasive pathogen that causes bleeding stem lesions and foliage dieback on some species of trees.

“The presence of Phytophthora kernoviae has been confirmed at two sites, but as yet has only been isolated from one species, namely cherimoya or custard apple. The fungus was only detected in a soil sample from the second site.”

“At this stage the origin of the fungus is unknown. Biosecurity New Zealand has not been able to establish any link to imported material and investigations are continuing into the distribution of this fungus.”

The fungus was first detected and described in the United Kingdom by scientists working on the Sudden Oak Death pathogen caused by the related species Phytophthora ramorum. In the United Kingdom Phytophthora. kernoviae has been associated with leaf necrosis, stem die-back and “bleeding cankers” on a range of species including oaks, rhododendrons, beech, as well as magnolia and other ornamental species.

Biosecurity New Zealand is working closely with scientific experts to determine the distribution of the fungus. Biosecurity New Zealand has advised the Department of Conservation and both the Northland and Auckland regional councils of this detection.

- Two sites in Northland are known to be infected by Phytophthora kernoviae.
- It has caused damage to some ornamental species in the UK.
- It has a wide range of hosts.

ENDS