CSIRO scientists develop biocontrol strategy to tackle invasive species

Years of research has culminated in the agent being deployed to Australia's southern coastline, as part of a wider effort to kill an invasive species affecting birds beach nesting.

The fungus from France will fight sea spurge, a weed introduced from Europe in the 1930s, which has spread right along the south coast from Western Australia and now into NSW.

Growing up to 120 centimetres high, sea spurge can get so dense it makes it difficult for shorebirds to nest. When the plant is damaged, it oozes a latex which is an irritant to both humans and animals, impacting the appeal of Australia's great tourism asset.

The CSIRO biocontrol team at Black Mountain has collaborated with colleagues in Brisbane, Western Australia and Montpellier in France to import the biocontrol agent from Europe.

Releases have already been made in Tasmania and now the three year trial will begin at London Bridge, a natural offshore arch in Port Campbell National Park in Victoria.

The NSW government will provide funding for the trial as part of its effort to reduce sea-spurge seeds spreading north via ocean currents.

CSIRO research scientist Dr Gavin Hunter said adult sea-spurge plants produce up to 20,000 seeds and can maintain viability in the ocean for a long period of time.

Dr Hunter said the current "zero tolerance policy" to control sea spurge was manual removal of the plant and the application of herbicide.

"There's an active management going on in NSW, but any other strategy that can be used to prevent sea spurge coming into NSW is obviously valued, this potentially could represent one of those strategies," he said.

The fungus has been grown in a petri dish at the CSIRO laboratory in Canberra where it is mass cultured, dried and then sent to community participants to be sprayed on the invasive weed.

At the end of the three year trials in Tasmania and Victoria, it will be decided whether the fungus can be used to tackle sea spurge infestations across Australian beaches.

It is one of several biocontrol strategies the CSIRO currently has in development to combat invasive species, including African boxthorn and flaxleaf fleabane.

Researchers estimate weeds, Australia's most economically destructive species, cost the economy around $5 billion per year.

Grain growers alone spend more than $2.5 billion per year on weed control, according to the CSIRO.

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Dr Hunter said biocontrol was an effective tool against a growing problem, however, development was arduous, as had been the case with the fungus to tackle sea spurge.

Initial surveys to find pathogens of the plant began in Europe in 2009, he said.

"Those surveys resulted in the collection of a couple of insects and fungal pathogens of sea spurge and one of those agents was a fungal pathogen that showed promise," he said.

In 2017, funding was secured to transport the candidate from Europe to the quarantine facility in Canberra.

"We went through a two and a half year period of intensive experimentation with the fungal biocontrol agent in our quarantine facility," he said.

"Then we applied to release the agent in Australia as a bio control agent.

"Now we're kind of really in the end phase of the whole process."

Dr Hunter said while biocontrol does not offer a silver-bullet solution, it does provide a promising defence against the increased threat of invasive species.

"Due to climate change and due to the increased movement of goods and people across borders, the chance of introducing an inverse organism or an invasive species into Australia is really high," he said.

"If there are any invasive organisms that do get into Australia, biocontrol is one tool that we can use to mitigate the further spread and impact that invasive plants could have on our environment."

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