Wollemi pine infected by fungus
The only wild population of the precious Wollemi pine is under threat from a fungus that has already wiped out other trees, Australian experts say.
And unauthorised visitors to a remote valley west of Sydney probably brought the fungus with them when they visited the 'secret' home of these Jurassic-era relics.
Dr Tony Fleming, head of the National Parks and Wildlife Service in New South Wales, says the root rot fungus, Phytophthora cinnamomi, was this week confirmed in soil, and in at least one tree.
"This is a microorganism that can be extremely serious for plants that are susceptible to it," says Fleming.
And, he says, the recent drought may have put the trees under more stress and made them more susceptible to the fungus.
Fleming says Phytophthora was responsible for the dieback of large areas of jarrah forest in Western Australia.
"The worst-case scenario with dieback is that you lose all the plants," he says.
Fleming says that apart from fire, Phytophthora has always been considered a major threat to the Wollemi pine.
"The real issue for us is how far it has spread within that site," he says.
Catching it early
Fleming says the fungus was found during routine monitoring and further sampling of the site is planned.
"We're hopeful we've caught it early and that we can take steps to try and contain the infection of the site," says Fleming.
He says fungicides might be injected into trees and soil, after they are tested on cultivated pines to make sure there are no negative effects. And drainage patterns around the trees may be changed to minimise the spread of fungal spores.
"It may not be possible to get rid of the fungus altogether," says Fleming.
"The challenge may be now to contain it to a small section of the site and to provide introduced fungicides that can suppress its activity."
"The fact that the Wollemi pine tends to reproduce itself by cloning makes scientists more concerned about the chance the fungus will wipe out the wild stands.
But Fleming says it's too early to know the trees' chance of surviving.
How it happened
Although the wild stand of Wollemi pines are in a remote part of Wollemi National Park, Fleming says uninvited visitors probably introduced the fungus.
"Phytophthora is a soil-borne pathogen. Its spores can be spread by water. It can also be spread on the soles of feet," he says.
Staff checking the trees must sterilise clothes and equipment before entering the site to make sure they don't bring in unwanted diseases.
But Fleming says footsteps and campsites have been found in the area and word has got around that the general public has visited the site.
He says it's not likely that anyone would have stumbled across the pines while bushwalking.
"You need to be a canyoner to get into the place," he says.
"There are some people who treat it as a bit of a challenge and they want to be able to ... brag about it at the pub."
The Wollemi pine was discovered in 1994 and there are fewer than 100 adult plants in the wild.
Scientists hope that commercialisation of the tree will help protect it.
"This is a species which is of extraordinary scientific significance," says Fleming.
Last month, an auction of cultivated Wollemi pines in Sydney raised A$1.59 million (US$1.17) with trees sold for A$2000-$7000 each. One anonymous bidder paid A$115,000 for a set of trees.
From April next year, 500,000 more trees will be sold to the public.