Chilean Needle Grass Rust Fungus Approved

A rust fungus that affects Chilean needle grass could help slow the spread of the highly invasive weed in Marlborough.

The Environmental Protection Authority (EPA) has approved the release of the fungus to control the spread of the grass which is widespread in Marlborough, with 2,615 hectares affected.

Councillor Barbara Faulls, who holds Council’s biosecurity portfolio, said without an intervention such as the fungus, farmers, landowners and biosecurity staff were fighting an uphill battle against the damaging weed.

“Rust fungus (Uromyces pencancus) will hopefully give us the advantage of not having to search for the proverbial ‘needle in a haystack’, as it will spread and do its job without too much human intervention,” she said. “The fact that it is host specific is a comfort to landowners as well.”

Chilean needle grass, a perennial South American grass, was first recorded in Marlborough in the 1940s in the Blind River area. Plants form dense clumps, excluding pasture species,reducing farm productivity with the potential to cost farmers millions of dollars in lost production. Animal welfare is also an issue as the seeds have sharp tips that can get into pelts and eyelids, causing blindness.

Marlborough District Council applied to use a strain of rust fungus, Uromyces pencanus, as a biocontrol agent against Chilean needle grass (Nassella neesiana) in New Zealand.

Council’s Biosecurity Manager Liam Falconer described the release as “significant” and had involved many years of work from councils, Landcare Research, EPA and the community.

“We hope the rust will become well established in Marlborough, slowing the growth and seeding ability of Chilean needle grass and reducing harm to livestock and loss of production,” he said.

“Testing shows this rust fungus can successfully slow infestations, killing the foliage of Chilean needle grass as well as reducing its growth and seed production.”

Liam says that biocontrol is a long game and it may take a number of years before an impact from the initial releases is seen.

“This rust fungus is hostspecific, meaning it only lives on Chilean needle grass and is highly unlikely to harm native plants or animals. There is also no risk to people,” he said.

A study has estimated the potential cost of lost production could reach as much as $1.16 billion nationally, if the weed is left unchecked.

In recent years the EPA has approved other biocontrol agents for old man’s beard, Sydney golden wattle and moth plant, amongst other pests.

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