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Water hyacinth weed found in Mission Heights Reserve

Published: 22 August 2018
A water hyacinth weed infestation. Photo Biosecurity New Zealand

An eradication project is underway to rid a waterway in Mission Heights Reserve of the invasive water hyacinth weed.

Biosecurity New Zealand, part of the Ministry for Primary Industries, is carrying out a range of activities to control and ultimately destroy outbreaks of water hyacinth recently discovered in the reserve, with support from Auckland Council.

Water hyacinth is one of the world’s most serious and damaging freshwater weeds. It can choke waterways, badly affect water quality and it spreads very quickly. 

In New Zealand, it is an unwanted and notifiable organism under the Biosecurity Act 1993. This means it’s illegal to display, grow or spread the plants or seed.

“Water hyacinth can be spread by people moving it from an infested site. We don’t want it in New Zealand and will work hard to eradicate it from our waterways,” says John Sanson, manager of recovery and pest management for Biosecurity New Zealand.

Eradication methods

Eradication treatments of spraying and mechanical removal will be carried out during normal working hours. Any remaining water hyacinth plants will be hand removed or treated further with a herbicide.

“This is the first stage in what will be a long control and eradication programme. The removal process, once started, is relatively quick. However, the follow-up inspections and monitoring will continue for several years to ensure that the weed does not return from any seeds that may have remained on site.”

The public is urged to stay well clear of the site while work is carried out in the reserve.

“Public safety is imperative and we have placed clear warning signs around the affected area, and have visited neighbouring schools to reinforce safety messages," says Mr Sanson.

"Staying clear is particularly important for children and animals as infested waterways can look just like solid ground and they could fall through into the water beneath."

What you can do 

If you have water hyacinth in a pond or aquarium on your property or know where it is growing, it is important that you call the MPI pest and disease line on 0800 80 99 66 so it can ensure the plants are disposed of safely.

Find out more

More information is available on the Ministry for Primary Industries' website, or you can get in touch via email or download the water hyacinth fact sheet, available in English and Chinese.