Grass trees can live for centuries, slowly inching upwards year after year, but it only takes a month or so for them to die from the introduced plant disease Phytophthora dieback.
A "biodiversity bulldozer", according to ecologist Mark Garkaklis, dieback is capable of wreaking havoc on an entire ecosystem when it infects plants.
Australia's iconic grass trees and banksias are particularly susceptible to the disease.
"The pathogen can kill individual plants, but in some areas it will kill entire groves of grass trees," Dr Garkaklis said.
"The antechinus, the little pygmy possums, the potoroos and bandicoots, they actually live in our grass trees. When [the trees are] killed they've got no habitat."
A silent killer
Australia's most recent State of the Environment Report said Phytophthora cinnamomi — the soil-borne organism that causes dieback — was the second biggest introduced threat to endangered species after rabbits.
In the heathlands of Victoria's Otway Ranges, where dieback is present, a new trial is underway to stop the spread of the disease and protect the habitat of endangered animals.
Phytophthora is spread when humans or animals disturb or carry infected soil from place to place, or from water run-off.
Managing this "silent killer" is difficult, Dr Garkaklis said.
"We don't see it, it's moving through the soil and that makes it really hard."
Funded by the federal government's Wild Otways Initiative — a project to control a variety of pests and protect threatened species — the trial is using a salt-like chemical called phosphite to combat Phytophthora dieback.
Phosphite has previously been used to contain dieback in Western Australia.
Once dieback is present it can't be eradicated but it can be controlled, said Jessica Miller, environmental programs manager at the Corangamite Catchment Authority.
"[Applying phosphite to plants] doesn't kill the disease, but what it does is boosts the plant's immunity. So it's a little bit like an immunisation," she said.
As well as applying the phosphite spray on the ground, spraying from aeroplanes is also being trialled to halt the spread of dieback.
"We can protect a large amount of bushland fairly quickly and easily using aerial spraying," Ms Miller said.
Despite the potential efficacy of aerial spraying, "it's not our silver bullet", according to Katrina Lovett, a regional conservation program coordinator at Parks Victoria.
"Once we've sprayed you have to continue to treat the locations because they do lose that resilience, that immunity," Ms Lovett said.
However if the aerial spraying trial was successful and funding was available, Parks Victoria would explore if it could be applied in the management of Phytophthora in other locations across the state, she said.
Helping stop the spread
The project to combat Phytophthora also includes the mapping of the disease in the Otways and an education campaign to show the public how it can play a role in stopping the spread of dieback.
When people are walking, bike riding or driving through bushland they can spread the disease through their boots, tyres or other equipment, Ms Miller said.
"We're trying to reach people who love this place to protect it by being really careful about their hygiene," she said.
"So, arriving clean to the bushland then leaving clean, making sure they're not taking the disease with them back to their gardens or to other parts of bushland in Victoria."
A brochure explaining how to avoid carrying this unwanted guest around the bush has been produced as part of the project.
Understanding how to identify signs of dieback and avoid contaminated areas was also important, Dr Garkaklis said.
"If you walk into a patch of bush and you see a few grass trees and then there's some flat green areas with lots of sedges and small plants that's very likely been hit by Phytophthora," he said.
The yellowing of leaves on grass trees, or decaying stumps which have lost their leaves, are also signs of the disease.
"These are really old, iconic plants. They're the ones that you should see in the landscape and go, 'I've got to protect that,'" he said.
"If we lose our habitat, there's no going back."
