Weeds and other pests can damage New Zealand's economy, environment and way of life. Gardeners have a big role to play in protecting New Zealand from biosecurity threats. Find out how you can play your part.

How you can help

When you're gardening be on the alert for pests and diseases you haven't seen before. Call us if you're concerned – 0800 80 99 66.

To help stop the spread of weeds and other pests and diseases:

Weeds are a threat to our environment

A weed is a plant that is invasive or harmful. They are one of the biggest threats to New Zealand's farms, parks, coasts, bush, wetlands and alpine areas. Weeds smother the habitat of native plants and animals, and can harm agriculture through damaging crops and affecting animal welfare.

Many problem weeds in New Zealand's natural areas started out as plants deliberately grown in gardens.

Control weeds in your garden

Follow Weedbusters' advice to get rid of weeds in your garden.

Weedbusters' 7 tips for weed control

  1. Find out what weeds you're dealing with first. Ask for expert help.
  2. Start small. Avoid creating large cleared areas which often allow new and different weeds to establish.
  3. Plan your control and work in stages. Tackle outlying weed patches first to slow the rate of weed spread before starting on the worst areas. Replace weeds with natives or non-weedy plants as you go.
  4. If your weeds need chemical control, contact Weedbusters to find out the best herbicide to use and how to apply it. You may need permission or qualifications to use herbicide on public land.
  5. Destroy weeds before they fruit or seed to prevent a new generation of weeds growing inside your work area.
  6. When shifting dead weeds take care not to spread any seeds or fragments around that could grow again.
  7. Decide on the best disposal method to use before you start, particularly if working in a large area.

Legal restrictions for some plants

Some plants are banned from sale, distribution, display and propagation. These plants are listed on the National Pest Plant Accord (NPPA) list and have all been classed as 'unwanted organisms' under the Biosecurity Act 1993.

Plants on the NPPA list should not be available in garden centres or other shops.

If you have a plant in your garden that is on the NPPA list, you are not legally required to remove it but you must not sell, display (for example at a flower show or garden walk), propagate, or move it to another garden.

Dispose of greenwaste correctly

Greenwaste – clippings, branches or plants you've taken out of your garden and don't want – can spread weeds if not disposed of correctly.

Gardeners should check their regional council's website and the Weedbusters website for information regarding what to do with their greenwaste.

Find out more

Don't bring plants or seeds into New Zealand

Goods coming into New Zealand by air, sea, or mail need to pass strict biosecurity requirements to prevent the introduction of pests and diseases.

You must not bring plants, plant materials, or seeds into New Zealand in the mail (for example online shopping, or if a friend or relative posts them to you), or in your bags when you come home if you travel overseas.

Importing seeds for sowing

Importers of seeds for sowing in New Zealand need to meet various biosecurity and phytosanitary requirements.

Pests to look out for in the garden

The main pest species MPI asks gardeners to be on the lookout for are:

Brown marmorated stink bugs

MPI needs your help to keep watch for the brown marmorated stink bug, which could attack a wide range of New Zealand crops and infest local homes. Gardeners have been asked to be on the lookout because bugs that come through airports or seaports would attack their crops first. If you think you’ve found one – catch it and call us immediately on 0800 80 99 66.

Cape tulip

Cape tulip could have a serious economic impact on New Zealand agriculture if it were to become widely established because it can smother pasture. It is also very poisonous. Although it has been banned from sale since 1950, sometimes plants are still found in private gardens. If you think you’ve seen this plant call us immediately on 0800 80 99 66.

Myrtle rust

The myrtle rust fungus is not present in New Zealand. If you think you see myrtle rust on any plant you must call us on 0800 80 99 66. Do not attempt to touch the fungus or collect samples as this may increase the spread of this disease.

This fungus is a threat to any member of the myrtle family, including native species such as pōhutukawa, rātā and mānuka.

The first signs of myrtle rust are powdery, bright yellow or orange-yellow pustules on leaves, tips and stems.

Invasive ants

Most ants you will see in your garden are not a concern. However, we need to keep watch to ensure some species of invasive ants don't get established here. Early detection is important to the eradication and control of invasive ants.


New Zealand has 15 species of mosquito. They are a nuisance, but not dangerous. Mosquitoes breed in standing water, so the best way to get rid of them is to remove things that hold water from your garden.

Mosquitoes from overseas are a threat to our health, as many of them can carry dangerous diseases. 

There are 3 species of exotic mosquitoes that we ask to you keep a close look out for – Asian tiger Mosquito, malaria mosquito and southern saltmarsh mosquito.

Read more about these mosquitoes

Pea weevil

Pea weevils were found in April 2016 in the Wairarapa. MPI needs your help to rid the area of this pest and prevent it from establishing in New Zealand.

There is a ban on growing peas in the Wairarapa until July 2018 - do not grow green or sugar snap peas in this area. This ban applies to both home vegetable gardens and commercial crops.

If you think you have found a pea weevil, catch it and call us on 0800 80 99 66.

Potato wart

Potato wart is a fungal disease which, if it was to spread to commercial properties, would have a serious impact on New Zealand's potato industry. Although it doesn't pose a threat to human health, diseased potatoes are not fit for human consumption. The most recent reports of potato wart were in home gardens in and around Invercargill, in 2012.


Salvinia is an aquatic fern that forms floating mats on still waters and swamps. It can completely smother waterways and badly affect water quality. It can double in area within 2 weeks in warm conditions, such as in the north of New Zealand. Gardeners with fishponds or other still ponds should keep an eye out for salvinia.


Subterranean termites can cause structural damage to all types of wood, including timber house framing, furniture, fences and trees. Occasionally these introduced termites are found in New Zealand and MPI is keen to identify any populations and eradicate them. If you see any termites call the MPI Exotic Pest and Disease Hotline on 0800 80 99 66.

Water hyacinth

Water hyacinth forms dense mats, completely smothering large waterways and badly affecting water quality. These mats kill off native plants, attract breeding mosquitoes, block dams and irrigation systems, remove oxygen from the water and create a drowning risk for people and animals. If you see water hyacinth you must call 0800 80 99 66.

White bryony

White bryony smothers and shades out whatever it grows on. It is dispersed by birds and its tubers are hard to find. White bryony grows in diverse habitats such as hedges, fence lines, native forest, scrub, paddocks and exotic plantations. Plants are usually found under places where birds perch.

If you find this plant, call 0800 80 99 66.

Find out more

Who to contact

If you have questions about biosecurity and gardening, email

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