MEDIA RELEASE

Thursday, November 03, 2011

Microscopic weed eaters help stop the spread of broom and thistles

A meal of broom and Californian thistle sounds less than appetizing to most, but Horizons Regional Council’s latest recruits are hungry to stop the spread of weeds.

The broom gall mite and green thistle beetle are bio-control agents introduced to munch through two of the region’s toughest weeds and Horizons environmental coordinator Craig Davey says they are proving a hit with farmers.

“Broom is still actively spreading throughout our region and Californian thistle is a thorn in the side of the rural community with a huge impact on stock and production costs,” he says.

Bio-control is a commonly used method of controlling particular types of weeds using insects or disease that prey on a specific weed without damaging other plants. The last release of these insects was in 2010 in the Tararua and Central Plateau area where they are hoped to establish and start to spread.

The microscopic broom gall mites work by attacking broom and form galls that can cause stunting, reduce flowering and kill the plant.

“These agents are a fantastic tool to have in the weed management tool kit and we’ve seen them become extremely effective in Canterbury where they have killed bushes”

Broom is named in Horizons’ Regional Pest Plant Management Strategy as a ‘boundary control’ plant, meaning horizons staff will respond to complaints regarding property boundary matters and we will release and manage biological control agents of broom. Horizons aims is to work with the public to ensure broom does not spread and the current infestations are reduced.

Broom can be identified by its golden-yellow pea-like flowers and upright woody stems, while Californian thistle has lance-like leaves with strong spines and a mass of seeds with fluffy white hairs in summer.

Horizons is now seeking registrations of interest in the next release of broom gall mite. If you suspect you might have one of these weeds on your land and want a helping hand to control it get in touch with Horizons 0508 800 800.

ENDS

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