Tackling kauri dieback
Ivisited Ta¯ ne Ma¯ huta on my first trip to Aotearoa New Zealand. I was in Northland to meet my prospective in-laws and see the sights. I remember standing in awe of the ginormous tree, contemplating what the world was like more than 1000 years ago when Ta¯ ne Ma¯ huta was just a sapling.
Twenty years later, and kauri is officially one of the most endangered plants on the planet thanks, in part, to kauri dieback disease.
Kauri dieback is caused by a weird microbe called Phytophthera agathidicida, which looks and behaves a bit like a fungus but makes multiple types of spores, including swimming zoospores that spread the disease between trees. Unfortunately, there are very limited chemicals available to treat kauri dieback.
That’s something Dr Monica Gerth from Victoria University of Wellington is trying to solve. As part of her MBIE Smart Ideas grant, she and her colleagues partnered with Chris Pairama (Te Taou¯ , Nga¯ ti Wha¯ tua) and Ian Mitchell of
Te Uri Taniwha, Nga¯ puhi, Waima¯ , to explore whether Ma¯ ori knowledge of forest health can identify native plants that produce antiPhytophthora compounds.
Using ma¯ tauranga that descends from Te Whare Wa¯ nanga o Nga¯ puhi – the sacred house of learning of Nga¯ puhi – four plants were selected for testing: ka¯ nuka, karamu, kawakawa, and nı¯kau.
The team found that leaves from one species of ka¯ nuka, Kunzea robusta, produced compounds that stopped zoospores swimming and germinating, at least in the lab.
This suggests that planting ka¯ nuka next to kauri, or developing sprays or soil drenches from these compounds, might be an effective way to stop the spread of kauri dieback, though there is still more research needed.
The work is a wonderful example of how research should be done. For too long, advances have been made using the exploitative Western model of ‘‘helicopter science’’ – researchers drop into an indigenous community, take the samples or knowledge they want, then leave, and the community never hears from them again.
Scientists need to recognise that indigenous communities, and the plants and animals that are their taonga, are not simply resources to be exploited. Instead, ethical collaborations like this are the key to success.
Planting ka¯ nuka next to kauri or developing sprays or soil drenches from these compounds might be an effective way to stop the spread of kauri dieback.