Armillaria novae-zealandiae is also known by Māori as harore. Photo / Supplied
Armillaria novae-zealandiae is also known by Māori as harore. Photo / Supplied
An indigenous New Zealand fungus may help to control wilding pines – one of the country's most ecologically damaging weed species – a student's research project shows.
Wilding pine control costs New Zealand millions of dollars a year, and involves the expensive and time-consuming methods of cutting down the trees and spraying herbicide from the air.
Control seldom totally eradicates the pines, which often reinvade sites some years later.
Armillaria novae-zealandiae, also known as harore, is a fungus that feeds on decaying wood.
It is common in native forests, where it is a natural part of the ecosystem and helps decay fallen trees.
Her study was part of a Bio-Protection Research Centre student research programme.
Supervised by Bio-Protection Research Centre principal investigator and University of Canterbury Professor Ian Dickie and his colleague Dr John Pirker, Early tested what age of wood it grew best on (ranging from live and freshly harvested wood to old and decayed wood).
"The research aimed to address knowledge gaps in our understanding of Armillaria, and eventually investigate whether we could use it as a biological control of invasive pines," Early said.
"Some of the questions we have about using it, for example, are whether we can introduce it to grassland areas that are susceptible to wilding pine invasions, where it doesn't currently exist, and whether introducing it at the same time as pines are felled would prevent reinvasion."
The results were promising, and Armillaria novae-zelandiae with showing the best growth, Early said.
"We tested several isolates of this species and all of them grew larger than the other Armillaria species. It also consistently grew most vigorously on live or freshly-felled pine wood."
Armillaria's strong growth on live or fresh pine wood was important, Early said.
"It's really promising that all the fungi grew best on live or fresh wood, as this implies that we could potentially design a way to inoculate wilding pine sites with Armillaria at the same time we are manually clearing trees and using herbicide."
This could be practical and economical if "we don't have to plan more site visits to use the fungi" Early said.
Biology student Genevieve Early. Photo / Supplied
"We also want to find out if this will accelerate decomposition and reduce wildfire risks."
A. novae-zelandiae had been used as a food source by Māori, who should be involved in continuing research, Early said.
"Using it as a biological control may be of particular interest to iwi in areas badly affected by wilding pines, as a way of protecting landscapes and ecosystem values."
Professor Dickie said his group was seeking funding to continue the research, particularly looking at how Armillaria affected native seedlings, to test whether it could be used to clear pines in areas where ecological restoration was planned.
"Until now, we've been good at killing pines, but not at restoring ecosystems," Dickie said.
"We are winning the battles, but losing the war. This fungus may be the key to not just killing pine, but to keeping it from reinvading, and to restoring ecosystems."
