Science

CSIRO releases Brazilian leaf smut fungus to target and kill invasive weed


Australia’s national science agency will release a Brazilian leaf smut fungus to target and kill an invasive weed that covers large parts of the continent’s east coast.

Researchers from the CSIRO say the scourge of wandering trad could be slowed by the introduction of the Kordyana brasiliensis fungus, which they have called its “natural pathogen”.

The fungus poses no danger to other plants, according to the CSIRO’s extensive testing.

Dr Ben Gooden from CSIRO said scientists had spent years testing the fungus, and were now ready to begin a gradual rollout.

He said it was like “reuniting” wandering trad with its “natural enemy”.

Originally introduced from South America as an ornamental plant, wandering trad covers large parts of Victoria, New South Wales and Queensland, and chokes native plants, rivers and ecosystems.

“It is a significant invasive weed of temperate ecosystems,” Gooden said. “It can smother these cool, temperate ecosystems. What we are seeing is a significant drop in plant diversity, which has cascading negative effects on the ecosystem.

“The smut fungus is from Brazil, which is where wandering trad is native to. It is a natural pathogen … The fungus will invade the leaf of the trad, and depletes the cells of the plant of nutrients.

“Over time the leaf that is infected will die. That leaf will then produce fungal spores that then move to another leaf.”

CSIRO was approved to release the fungus by the Department of Agriculture and Water Resources in December.

The fungus will first be tested on a few small sites in the Dandenong Ranges, before being given to community workers in three Victorian councils – Yarra Ranges, Knox and Cardinia Shire – who spend their time fighting weeds.

“Several years of testing and review by the government was undertaken to evaluate that the agent was safe for release in Australia,” Gooden said. “We had to make sure the fungus does not damage native plants.

“If there is any significant risk of the fungus affecting native ecosystems, it wouldn’t be released. It is host-specific to wandering trad.”

Gooden said the response from volunteers who tackle wandering trad was of relief and excitement.

“Most weeds are managed, for free, by local community members,” Gooden said. “The reaction has been really good.

“The main problem for wandering trad is that you can pull the weed up with your bare hands and it has very little impact over large spatial scales. People were desperate. They needed something to assist them.”

But Gooden warned that it would not happen overnight.

“It won’t completely eradicate trad, but we hope it will reduce the cover of trad,” he said. “It’s going to be a slow and steady progress of infection, leading to a reduction of the target weed.”

If the trials are successful, researchers hope to apply the fungus nationwide in a few years.



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