The mighty kauri, an icon of the New Zealand bush, is under attack.
The enemy is a microscopic water mould, which doesn't sound very scary but is already responsible for the deaths of thousands of kauri trees across the upper North Island.
Some scientists believe the situation could get much worse. So are we now facing the prospect of a future without kauri trees?
Wes Bycroft has lived among the kauri of West Auckland for over 30 years.
He says the ancient trees are an important part of his life.
“We just love the bush and of course the kauri trees were a special feature of it...We've got quite a few at the top here and then further down through the bush we've got a flat area with a little clearing and it's got even bigger kauri” he says.
But five years ago, the Kauri started dying and this has concerned Mr Bycroft.
“It's got us really worried. We've invested a fair chunk of our life living here and being part of that environment and we're dead scared we're going to lose all the kauris around our house.
“It's horrible. The one we cut down, back in the 70s when we went past to the long drop loo, I used to hug the thing. It sounds silly but in fact you got to know the trees as an individual tree” he says.
It is not just Mr Bycroft who is feeling the pain.
Nick Waipara of from Auckland Regional Council’s biosecurity team said the dying kauri is a major problem.
“We've got areas where there's been 50 trees, 100 trees that are declining or dead. We know that seedlings, saplings, the young rickers and the big trees are affected by this and so it's taking out all stages of the kauri life cycle” he says.
Mr Waipara adds that kauri are dying right across the upper North Island. With the hardest hit area West Auckland’s Waitakere Ranges.
The area of biggest concern is the Waipoua Forest in Northland, home to the biggest kauri of all -Tane Mahuta.
But while the victims are massive the cause is microscopic and Mr Waipara says it’s all thanks to a pathogen infecting the kauri root systems.
“What's happened basically is that the disease, the pathogen, has infected through the root system and moved up the roots and arrived at the base of the trees. So what you're seeing is the trees reaction to the infection which is what we are calling gumosis or the gum bleeding and that's the reaction of kauri when they're damaged or when they're being infected or attacked by insects…so this is a reaction to the pathogen having entered inside the tree... Yes.”
The name of that giant-killing pathogen is Phytophthora Taxon Agathis or PTA.
The organism is a close relative of the one that caused the Irish potato famine in the 1840s but this one only attacks kauri trees.
Ross Beever from Landcare Research says that when it comes to diseases that affect kauri trees, this is the worst.
“We know of lots of diseases of kauri but by and large they don't kill the kauri stone dead, whereas the evidence is that this one in fact does that and can kill even the large giants” he says.
Mr Beever explained that it doesn’t take much for the pathogen to get to work.
“Gradually it creeps up the stem to the base of the trunk. It never gets very high, never more than a metre or so. At that stage it then spreads around the trunk and essentially ring barks the tree” he says.
That starves the tree's branches of nutrients causing them, then the whole tree, to die.
Mr Beever is hoping it won’t be long before a solution to the problem is found.
“In the longer term there may well be ways that we can target and sort of cure, to some degree anyway, infections on individual big trees. There are chemicals that can be used potentially for this purpose but we need to trial them and see how they work in kauri and this is a bit challenging because we're not dealing with a sort of orchard of nice uniform trees, but there are techniques out there to do that,” he says.
In the meantime the catch-cry is prevention.
The Government recently gave $4.7 million dollars towards fighting the disease which is spread by soil and water movement alone.
Mr Waipara says there are things we can do to help prevent the disease from spreading.
“It's that transfer of dirt or soil through say footwear, tyres, equipment being dirty and having those spores in them and that's how it will move. So a simple message of making sure you have clean equipment, tyres, and shoes when you're visiting kauri forests is a simple message I think and most New Zealanders would buy into that especially if they know that can then help the kauri,” he explains.
It's a message that Wes Bycroft hopes will catch on quickly.
He's already lost several old friends and doesn't want to lose any more.
“We would like to see these trees carry on for the rest of our lives and so yeah we have a definite emotional attachment to the place and the trees are a special part of that.”