Local Focus: Serbian gall mite cleared for fight with Old Man's Beard

One of the country's most noxious weeds mite have met its match.

Horizons Regional Council, on behalf of the National Biocontrol Collective, has been successful in its bid to be the first in the world to use a mite for biological control against the invasive weed Old Man's Beard.

In a year's time, the mite would be released near Taihape, in the heart of the Rangitikei region, where the suffocating plant was first introduced around 100 years ago.

Old Man's Beard was a nasty weed which cloaked vegetation and killing other species such as native trees and plants. The seed spread quickly and was found throughout the country.

The fight against Old Man's Beard hasn't been easy or quick. Horizons Council has poured half a million dollars into controlling the pest by spraying, cutting and supporting local communities to do the same each year.

While this work has helped slow the spread of the weed, it was hoped the mite would make a real dent to its growth.

Horizons environmental programme coordinator Craig Davey said the mite would enable the weed to be controlled in places where it was too dangerous to use pesticides because of the native flora beneath the Old Man's Beard canopy.

"This will be a world first in terms of using a mite against Old Man's Beard," Davey said. "We have attempted other forms of biocontrol including a sawfly, leaf miner and fungus which haven't been very successful.

"We're really excited by this new one as we have seen how successful gall mites have been on other pest plants."

The gall mite was aptly named. Growing galls on the weed, similar to a wart or a boil on a human or animals, it prevented the plant from flowering and growing.

Extensive testing has been completed as part of the EPA application to ensure the gall would will not pose a danger to other plant types.

The mite was expected to be imported into the country in Autumn 2019, for release the following Spring.

"We are planning to make the first introduction of the gall mite to the Taihape area. Many unique and wonderful habitats have been ravaged by Old Man's Beard," Davey said.

"As we have a really engaged community in the Rangitikei, we'd like to locate these mites in the places too challenging or risky for chemical control."

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