A fungal super weapon has been released on Tasmanian beaches which could turn the tide in the fight against one of Australia’s worst weeds.
- Sea spurge is an invasive weed from Europe which has spread uncontrollably across Australia’s southern coastline
- The plant is too widespread to be hand weeded or controlled with pesticide
- The CSIRO has tested a fungus from the plant’s native habitat in France, which is set to be released on Tasmanian beaches
The weed is called sea spurge: It’s a small succulent shrub that looks like a lot of other native coastal vegetation.
It came to Australia from the coastal regions of France and swiftly took over the coastline from Geraldton in Western Australia, south and around the coast towards Sydney.
Since 2007 volunteer John Marsden-Smedley has been fighting a losing battle against sea spurge in Tasmania.
He and a team of volunteers have pulled out 14-and-a-half-million plants from Tasmania’s beaches, but that’s hardly put a dent in the population.
“Here on the north coast of Tasmania, there’s 100’s of millions of plants on this one beach … it’s just soul-destroying,” Mr Marsden-Smedley said.
“We’ve spent 8,000 days removing the weeds, that’s worth nearly 2.2 million in volunteer hours alone, and that’s just one beach.
Along the NSW south coast the weed reinvades sand dunes, as the seed travels on the sea. According to the CSIRO, spurge is affecting threatened native fauna and flora and Aboriginal heritage sites.
We will fight them on the beaches
The fungus that’s set to take the fight to sea spurge is called Venturia paralias and was discovered by research teams on the coast of France.
CSIRO researcher Dr Gavin Hunter has been testing it since 2017.
“Initially the fungus infects the leaves, which can create a lesion on the leaf, but more importantly it can move from there into the stem,” Dr Hunter said.
“It affects the plant’s ability to photosynthesise and we’re confident that it’ll affect its ability to reproduce.
Dr Hunter said there’s no danger the fungus will attack other species.
“Our testing has occurred over a period of a few years: We’ve tested it against a large number of related species,” he said.
“We’ve found it to be highly specific.”
Turning the tide
Back in Tasmania, Venturia paralias has been released on three separate beaches as part of the pilot program to test if it would spread and thrive in Australian conditions.
Mr Marsden-Smedley has overseen the release of the fungus, he said it gave him great hope for the future.
“I’m really looking forward to being able to go back to those areas and not think that they’re immediately at threat.
“The areas that I frequent are part of the world heritage area, it’s an area that’s reserved for its ecological and cultural values, and I like to see it stay that way.”