I don't know a great deal about conservation issues pertaining to fungi. However, I did a bit of reading and the cause of Kauri dieback is know to be Phytophthora agathidicida - an oomycete (organisms distinct from fungi).
It appears that development of disease-resistant cultivars is currently the key management strategy.
I'd be intrigued to see research screening wood-decay fungi against Phytophthora. Continued in next post...
It may be that some of the indigenous wood-decay fungi in NZ are capable of producing compounds which kill or contain the Phytophthora. Those species could then be intentionally cultivated in containment rings around existing Kauri populations, forming a sort of defensive shield.
This is pure speculation on my part!
I'd also look for what else might be causing imbalances in the soil microbiome (could be pollution or climate change).
It's sad to see such beautiful trees being effected.
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