The following is a set of notes taken from a recent conversation between Travis Ashcroft, team lead for kauri research at Ruakura, Hamilton and Tony Walton. This was a follow up to a request for more information relating to

  • Distribution of healthy and infected kauri by geographic area
  • A request for more detailed information on infected and healthy trees than is shown on the published map of infected kauri sites, and related to surveyed / non surveyed areas, and protected / non protected areas
  • An explanation of why some separate areas of kauri are healthy, even though they may not be far apart (EG Waipoua and Waima Forests)
  • To what extent has research (continued to) look at the impact of overall tree health on the resistance to kauri dieback

Please respect the following as being just notes only – there is possibly no new news here, but it is important that the topic is discussed at a practical, non emotional level so that we can then make our own judgements as to what to expect over the coming years.

The key points made by Travis were :

  1. There is no way at present to declare an area is completely free of kauri dieback
  2. The disease develops at different rates
    • Seedlings – a few weeks
    • Rickers – around 6 years
    • Mature trees – decades
  3. Research is interested in three key impacting factors
    • Moisture level
    • Humidity
    • Temperature
  4. At present the major research focus is on looking for short to medium term answers
    • Research funding is around $800k per year
    • Which is significantly less than diseases of commercial crops
  5. A key method for determining infection is via soil samples, which have a guide cost of $200 each and take 20-30 days to provide a result– for any site, many samples are required, but they are still not foolproof
  6. Any disease requires
    • A pathogen
    • A host
    • Environmental conditions – in general it is not known what causes diseases
  7. Discussion around pigs and other forest dwellers – research on pigs has been focused on what they eat and leave as waste products – that seems to be a minimal way of transferring the disease. But no research on what forest dwellers carry around on their feet
    • Discussion how people are drawn to look at kauri trees, whereas forest dwelling animals don’t just target kauri areas
  8. Cleaning stations appear to have been significantly ignored by locals and tour parties.
  9. There are other vectors, such as the effect of heavy rain / flood events – it is hard to know how much disease they have transmitted
  10. Contact details provided for the operational manager who potentially will be able to assist with the questions relating to a more detailed national kauri map or data.
  11. Discussion around biological control approaches
    • Auckland Council has been conducting research into products that could improve kauri health
    • But this does not include fertilisers
    • Phosphite is a bandaid approach – injections need to be repeated every 3-4 years. They do not cure the disease
    • More environmental testing is expected over the next year
  12. It will not be possible to eradicate kauri dieback disease
  13. In longer term research, a key approach will be looking at genetic resistance options
  14. Are there pathogen variations across geographic areas ? Earlier research (that may have been limited) indicated not. However new research on this is being done by Massey or Lincoln universities
  15. Research is being coordinated nationally, but individual groups can do their own thing – the key players are MPI, Auckland Council, CRI (Crown Research) – but overall the pool of scientists involved is quite small. There is a new science advisory group with a focus on coordinating research
  16. Overall
    • It is a very difficult pathogen to control
    • There are more questions than answers
    • Overseas research has not found any answers yet
  17. The Kauri Dieback website is likely to be updated in a few months to include more research information – research papers go through a defined process before they can be published
    • It is acknowledged that better communication is required
  18. With regard to the Waitakeres
    • Infected trees will die
    • Measures can only control, reduce the spread of the disease
  19. In the bigger picture, with other diseases such as myrtle rust occurring, the overall task is to determine how to keep a whole forest healthy – with climate change providing challenges because of more tropical conditions

Conclusions to be drawn ?

  1. Don’t expect there to be any science answers in the near future – there are too many unknowns, and the amount of research that can be done is financially limited
  2. In the national funding picture, kauri dieback is not so important as diseases for commercial crops
  3. Where kauri dieback is present, the forest manager must determine how to reduce the spread of the disease
  4. Where kauri dieback is not visibly present, the forest manager does not know for certain that there is no kauri dieback, so they have to introduce measures to protect kauri just in case.