Dear Ministry for Primary Industries,

Recently I became very sceptic about the theory that Kauri Dieback is caused by Phytophthora agathidicida. In fact I couldn't find any scientist who confirmed that he/she still believes in that idea. Therefore I would like to ask:

1) What evidence exists that Kauri Dieback (= high number of symptomatic Kauri in a forest) is caused by Phytophthora agathidicida. Please don't just refer to articles. I want a short & clear description of the evidence.

In 2017 the statement was given to the public that "70% of infections are within 50m of a track" as evidence that people walking through the forest are spreading a kauri killing pathogen. But this information has been revealed as incorrect "fake news" (the latest survey of the Waitākeres showed only 23% of symptomatic kauri close to tracks). But I can't find any other evidence. I suspect that authorities are just not willing to admit a mistake.

2) Can you give me a list of New Zealand scientists who still believe in the idea that Kauri Dieback is caused by Phytophthora agathidicida mostly spread by people with their walking boots.

I have been in contact with many, and nobody has confirmed that to me.

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These are very important questions. The idea of science is to help society make good decisions. If you don't respond with clear and convincing answers it will confirm my suspicion that science is being distorted and misused for political and financial reasons and authorities are not willing to admit a mistake.

Yours faithfully,

Matt Munro

Dear Ministry for Primary Industries,

I am not satisfied with the information you provided in your response to my request.

In question 1 I asked for scientific evidence that Kauri Dieback (= high number of symptomatic Kauri in some of our forests) is caused by Phytophthora agathidicida. None of the 3 articles you mention do provide such evidence:
1 The research by Ian Horner was about exposing seedlings under laboratory conditions to a "sludge" with a very high concentration of Phytophthora agathidicida. The idea was to compare the effects with the effects of other Phytophthora. This was NOT evidence that in a natural forest with a realistic exposure to Phytophthora Agathidicida an actual damage is caused.
Please acknowledge the following quotes from the Black & Dickie paper you are mention on page 2 of your response: "As such, it is somewhat unclear if P. agathidicida is precipitating or only hastening kauri death" ... "For obvious reasons, trials have been restricted to young trees in artificial conditions. It is possible that trees under more natural conditions would be less susceptible compared to seedlings in the greenhouse" ... "Nonetheless, at present the degree to which resistance to P. agathidicida is present in the natural population remains largely unknown" ... "The occurrence of dieback in the absence of P. agathidicida should be a key area for research, to determine the role of other factors in forest decline" ... "More effort to determine and differentiate kauri dieback (the disease) from P. agathidicida (the pathogen), as it is not yet clear that there is a 1:1 correspondence" ... "One sentence that should haunt the KDP is ‘The early hypothesis (Burgan and Nelson 1972) that the Hawaiian rain forest decline was caused by a virulent pathogen or a combination of biotic disease and pest agents was ruled out after a decade of intensive disease research".
2 The paper by Weir et. al. does not contain any evidence for PA damaging Kauri. The quote you provided just reflects the opinion of some scientists at that time. The Black & Dickie paper was released after this article.
3 The latest report by Auckland Council about the 2021 survey in the Waitākere Ranges is actually strong evidence that PA is NOT the main driver of Kauri Dieback: in about half of the Waitakere Ranges (the central area) no PA was detected BUT symptomatic kauri were found here equally to the area with PA in the soil. At the soil around the roots of the vast majority (75%) of symptomatic kauri no PA was found AND most kauri where PA was found in the soil around their roots were healthy!
The "association" you mention between symptomatic kauri and the proximity to PA is easily explained by the susceptibility of sick kauri to be invaded by PA spores. In other words: PA is not causing kauri becoming sick, but kauri being sick are prone to be infected by PA. That means PA are just secondary pathogens waiting for a dying tree and then accelerating the decay.

So you have not provided any scientific evidence for Phytophthora agathidicida being the main driver of Kauri Dieback.
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In your response to question 2 you withholding the information about scientists still believing in the theory that Kauri Dieback is caused by Phytophthora agathidicida due to "privacy of natural persons". But this statement is absurd because all these scientists appeared in mass media (newspaper and television) during the Kauri Dieback debate in 2018. Based on incorrect information ("70% of infected kauri are within 50m of a track") everyone believed AT THAT TIME that "newly invaded kauri killing pathogen mostly spread on trampers boots" theory. But the situation has changed drastically, therefore I asked "which scientist STILL believes in that idea", which is a very reasonable question in public interest.

The botanists, ecologists, microbiologists and plant pathologists which appeared in newspapers and TV in 2017/2018 with contributions about Kauri Dieback were:
Auckland University: Nick Waipara, Cate MacInnis-Ng, Bruce Burns
Unitec Auckland: Peter de Lange
Lincoln University Christchurch: Amanda Black
Victoria University Wellington: Monica Gerth
Massey University Palmerston North: Richard Winkworth

I think it's obvious that it is indeed in public interest whether the majority of these scientists still believe that a recent incursion of a deadly pathogen mostly spread on walkers boots is the main driver of kauri dieback.

Yours sincerely,

Matt Albert Munro