Kauri dieback can live in pine trees and pasture, study finds

Wednesday, 4 July 2018

Dr Amanda Black says pine plantations may have a role in incubating and spreading kauri dieback disease.

Pine trees can host kauri dieback without symptoms, new research suggests.

Lincoln University masters student Kai Lewis also found common pasture plants could carry the kauri-killing disease.

A microscope photo of kauri dieback oospores on a culture plate.

Dr Amanda Black said in a statement her student also found the fungal-like disease, known as Phytophthora agathidicida, when it was young grew more rapidly in pine-forest and pasture soil than in kauri soil.

'This raises the possibility that kauri dieback may be moving from pine plantations and pasture into kauri forests, carried by people, animals, and even on machinery,' Black said.

Could forestry be spreading kauri dieback? Further research is called for.

* Tāne Mahuta could soon be infected with fatal Kauri dieback disease

* Fines and compliance officers to enforce West Auckland forest closure**

'We urgently need further research to find out if this is happening and how. Until we know the answer, we need to be very careful.'

Lewis also found two new species of phytophthora, Phytophthora pini and Phytophthora gregata.

These were present in kauri forest and pasture soils and their role in infecting native trees should be a high priority, Black said.

The research comes as it was revealed Tāne Mahuta, the country's largest kauri tree, could be infected with fatal Kauri dieback disease in less than a year.

In response to the research findings, Science Media Centre sent out a news release with comment from different scientists.

University of Auckland's Associate Professor Bruce Burns said the research was limited as it was done in a laboratory and not in the field, but its findings were 'highly significant' and gave 'warning signs that can't be ignored'.

The two new species of phytophthora found were known to cause disease in some plants overseas, he said.

Plant and Food Research's Dr Nick Waipara said the research showed kauri dieback could function outside kauri stands, 'which has significant biosecurity implications'.

'It is emerging that kauri is not the only plant host of agathidicida,' he said.

'That does not mean every infected host of agathidicida will succumb to disease symptoms and death, as kauri has, but clearly this pathogen can survive using other plants.'

Forest pathologist Dr Nari Williams said the study did not look at whether kauri dieback was present in pine forests or pasture.

'Many soil types and plants may have the potential to harbour this pathogen, and this is being examined in a current study,' she said.