McCahon trees a picture of health

Owning a Colin McCahon painting may be out of reach for many us, but how about a McCahon tree?

Some 600 saplings grown from cones picked from kauri trees surrounding the artist's former Titirangi home, now a museum, are being sold to raise money for the McCahon House Museum and The Kauri Project.

It's a unique collaboration between community, art and science groups - besides being harvested from trees that were the subject of some McCahon's most notable paintings, the saplings have already proven their worth to science.

In a New Zealand first, they were grown from trees infected with kauri dieback but are disease-free themselves.

A fungus-like disease which kills kauri of all ages and sizes, kauri dieback has devastated trees around Auckland, on Great Barrier Island and in Northland. It was discovered in the McCahon kauri trees three years ago and Chris McBride, then managing the McCahon House Museum, had the grim task of arranging for two of the 27 trees - all diseased - to be cut down.

McBride has since co-founded The Kauri Project which uses art to raise awareness and promote understanding of the disease. The groups says by linking artists with iwi, scientists and other researchers, art can become a tool for activism and education.

He says the remaining 25 McCahon kauri have the soil-borne disease, which causes yellowing foliage, loss of leaves, dead branches and lesions that bleed gum at the base of their trunks, but are being injected with phosphite to slow its spread.

Detail from Colin McCahon's Kauri tree landscape, one of his paintings inspired by the kauri that surround his former home.

But in a bold experiment in 2014, Auckland Council Biosecurity plucked cones from the very top of the trees - eliminating the chances of contact with soil - to see if disease-free saplings could be grown from them.

Lee Hill, senior biosecurity advisor for kauri dieback disease, says previous work had shown the risk of diseased seedlings was low but to mitigate any danger, they were kept in isolation and quarantine including at the Auckland Botanic Gardens in Manurewa.

"What we have shown here is that it is possible to produce healthy saplings from infected trees but I'm not advocating everyone tries it," he says. "We have followed very strict protocols and the plants have been under a very watchful eye for the past three years. We have also carried out rigorous testing to get to the level of confidence that we currently have about their health.

"That being said, it has proved the concept and I suppose that is something that should now be considered in the future, particularly as a way of continuing the lineage or heritage of an iconic kauri or stand."

The young trees are now in perfect condition for planting, but Hill says they are unlikely to have developed resistence to kauri dieback nor have they been injected with phosphite. This means the disease is still a risk to them and while there is research being done into resistence to it, it is a long-term project with no answers available yet.

The saplings are selling at $50 each, released as a 2017 limited edition. Each one is accompanied by a booklet, recording its edition number along with information about its heritage and how to plant and care for a sapling.

Vivienne Stone, director of the McCahon House Trust, which maintains the French Bay property, says all involved hope the project honours McCahon's legacy while helping to preserve one of the country's natural icons.

The trees can be ordered in advance (mccahon@mccahonhouse.org.nz or on 817 6148) or picked up on a McCahon Kauri Community Day on Sunday, August 6 at the Titirangi War Memorial Hall. The day will see leading specialists in biosecurity, artists and iwi talk about the disease and what can be done to stop it.

What can be done to stop kauri dieback:
•Learn more about the disease and how it is spread
•Clean your gear by removing soil before and after forest visits - clean your shoes, tyres and equipment
•Stay on the tracks and off kauri roots