Fungus fight Chilean needle grass growth

The use of rust fungus has been sanctioned in the fight against one of Marlborough’s most invasive weeds.

The Environmental Protection Authority (EPA) has approved the release of the fungus to control the spread of Chilean needle grass.

Council’s Biosecurity Manager Liam Falconer described the release as “significant.”

It has involved many years of work from councils, Landcare Research, EPA and the community, he says.

“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.

“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 biocontrol may take several years before the impact is noticed.

“This rust fungus is host‐specific, 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.”

Chilean needle grass is widespread in Marlborough, with 2,615 hectares affected.  It was first recorded in Marlborough in the 1940s in the Blind River area.

Plants form dense clumps, affecting 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.

Councillor Barbara Faulls, who holds Council’s biosecurity portfolio, says without further intervention controlling the weed is an uphill battle.

“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.

“The fact that it is host specific is a comfort to landowners as well,” Barbara explains.

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.