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Published: 2010-12-21 00:00:00

Environment Waikato is adding the South American lace bug to its armoury of pest plant control methods as it seeks to eliminate woolly nightshade in the region.

Woolly nightshade – also a South American import – is a serious threat as it:
• is toxic to people and stock
• invades pasture, native forest margins and urban areas, and quickly takes over, stopping other plants from growing.

Under the regional pest management strategy, woolly nightshade is subject to a “total control” rule which means land owners must remove any of it that appears on their land. However, woolly nightshade has become well-established in many areas, mainly in northern Waikato and the Coromandel.

Now EW is introducing the lace bug at two sites before Christmas to attack some of the worst woolly nightshade infestations to help stop it spreading. The bug – used successfully overseas and also being introduced in Bay of Plenty and Taranaki – feeds on woolly nightshade leaves and stunts its growth, thereby allowing other desirable plants to get better established. Lace bug only attacks woolly nightshade and will not affect other plant or animal life.

The heavily infested Waikato sites to get the lace bug before Christmas are 8 hectares near Port Waikato and 13 hectares near Whitianga on the Coromandel. Another Coromandel site, yet to be determined, will have the lace bug introduced next year, said biosecurity officer Darion Embling.

“The lace bug will be a very useful addition to our pest plant control armoury,” said Mr Embling.

“Lace bug has been effective in South Africa and we are confident it will have a positive impact here.

“Each release of the woolly nightshade lace bug costs about $4,000. Once the bug is established it should provide good value for money since woolly nightshade costs the Waikato economy a lot in terms of herbicide costs and its ability to displace more desirable plants, such as pastoral plants and native species.”

It is expected the lace bug will continue to be released in other parts of north Waikato and the Coromandel peninsula, as well as other areas where woolly nightshade can be difficult to manage. Mr Embling stressed, however, that lace bug was not a “silver bullet” that would allow the council alone to deal to woolly nightshade across the region.

“Lace bugs will be part of our tool kit in helping the regional community tackle the worst areas of infection. EW wants to help stop this plant getting out of control and we will look to make further releases over time.

“However, we will still need land owners to be very vigilant and to take responsibility for complying with the rules on their land so that woolly nightshade is controlled on their properties.”

For further  advice on how to tackle this pest contact Mr Embling on 0800 800 401 or at darion.embling@ew.govt.nz.