Biosecurity

How the council controls weeds

Auckland Council and Auckland Transport currently treat approximately 230 species of weeds in the region. We do this to protect and maintain assets and to meet amenity, safety and environmental objectives.

There is no single weed control method that will control all weed species. Different weeds respond to some methods of weed control and not others. 

The council makes decisions on which weed control methods to use in which locations based on:

  • effectiveness for the targeted weed
  • minimising potential effects on people and the environment.

These decisions are informed by the Weed Management Policy and Regional Pest Management Strategy, and by following best practice.


How we decide on weed control methods

The Weed Management Political Advisory Group oversees the implementation of the Weed Management Policy.

The group is made up of councillors, local board members and members of the Independent Māori Statutory Board.

Another group of independent technical experts, the Weed Management Best Practice Reference Group, provides objective, technical advice on weed management best practice to the advisory group and other governance bodies in the council.

This advice will also inform operational decisions made by council officers.

Weed Management Political Advisory Group

  • Councillor George Wood (Chair)
  • Councillor Arthur Anae
  • Councillor Ross Clow
  • Councillor Chris Darby
  • Councillor Wayne Walker
  • Councillor Penny Webster
  • Glenn Wilcox and Karen Wilson (alternate) - Independent Māori Statutory Board
  • Harry Doig  - Puketāpapa Local Board 
  • Graeme Easte - Albert-Eden Local Board
  • Jill Naysmith - Franklin Local Board
  • Izzy Fordham - Great Barrier Local Board
  • Paul Walden - Waiheke Local Board
  • Deborah Yates - Waitematā Local Board
  • Sandra Coney - Waitākere Ranges Local Board
  • Danielle Grant - Kaipātiki Local Board
  • Carol Elliot - Ōtāhuhu Local Board

Weed Management Best Practice Reference Group

  • Dr Margaret Stanley
  • Paul Champion
  • Dr Quentin Paynter
  • Dr Trevor James
  • Jo Ritchie
  • Jack Craw
  • Dr Meriel Watts

To contact either of these groups, email our weeds team.


Current weed control methods

A range of methods are currently considered by Auckland Council to control different weeds in different environments.

Mechanical
Control by weed eating, mowing or shredding. Restricts growth and reduces seed production, but not effective at killing the entire plant.

Manual
Control by hand, hand tool, or mulching. Effective against small shrubs and trees, and herbaceous weeds in small infestations, provided whole plant is removed including roots and tubers. Typically creates soil disturbance, which can lead to further weed invasion.

Biological
Control using a weed's natural enemy, such as insects or pathogens. Doesn't eradicate weeds entirely, but weakens them and reduces abundance, making other controls easier and allowing native species to compete.

High-pressure steam
Control by applying high-pressure steam. Restricts growth and seed production, but leaves roots primarily untreated. Ineffective against some weeds, such as nutgrass and kikuyu.  

Hot water
Control by applying hot water. Like high-pressure steam, this restricts growth and seed production, but leaves roots primarily untreated. Ineffective against some weeds, such as nutgrass and kikuyu.  

Plant-based herbicide
Control by spraying leaves with plant-based herbicide. Can control some weeds that hot water and steam don't affect, such as kikuyu. Must be applied more frequently than synthetic herbicides as it does not completely kill the weed. Mostly applied in the same way as synthetic herbicide.

Synthetic herbicide
Control by applying synthetic herbicide such as glyphosate. Effective when correctly selected for the target species, and when used as recommended. Kills the entire plant, including the root system, so can be applied less frequently.

No control
Where no weed control is intentionally undertaken. Can be beneficial over a long period on some sites and with some species; for example, no control of gorse in rural settings can help native species to regenerate. Intervention, such as maintenance work to tidy up sites, can make regeneration take much longer.

For more information on these control methods, including where and when they are used in Auckland, see weed control methods (PDF 88KB) or email our biosecurity team.


No-spray register

If you don't want weeds on the street frontage outside your property controlled with herbicide (synthetic or plant-based), you can join Auckland Transport's no-spray register.

As a condition of joining the register, you must agree to take over the control of weeds on your street frontage to the same standard.

If you do not control the weeds yourself, Auckland Transport will resume spraying.

You can also join the register if your property is on a park boundary and you don't want weeds on the boundary controlled with herbicide.

To register, visit the Auckland Transport website.


Glyphosate

Glyphosate is a broad-spectrum systemic herbicide used to kill selected weeds. It is one of the current weed control methods used by Auckland Council and Auckland Transport.

Glyphosate is available off the shelf at supermarkets and garden centres under many brand names, including Roundup, and is commonly used by the public.

Absorbed through the foliage, glyphosate spreads throughout the weed to the roots to kill the entire plant.

Because glyphosate binds strongly to soil, the risk of being spread by rain or irrigation is low. It also degrades quickly and has a low toxicity to terrestrial animals and wildlife.

Rules and requirements

In New Zealand, use of glyphosate is regulated by the Environmental Protection Authority (EPA), which has approved glyphosate as a herbicide for general use.

It is classified as a low-toxicity herbicide, and is not rated as toxic in respect to either dermal contact (touch) or inhalation (breathing).

In Auckland, all herbicides (synthetic and plant-based) must be applied in accordance with national standards, the Proposed Auckland Unitary Plan, and product labels as registered by the EPA. Complying with these standards minimises the risk of exposure to staff and the public.

For more information on glyphosate, see the Environmental Protection Authority website.

For more on the rules and standards under which glyphosate is applied in Auckland, email our weeds team or phone 09 301 0101.

Research

In March 2015 a World Health Organisation (WHO) sub-group, the International Agency for Research on Cancer (IARC), classified glyphosate as 'probably carcinogenic to humans'. This differed from the findings of another WHO group, the Joint Meeting on Pesticide Residues, which determined in 2004 that glyphosate does not pose a cancer risk to humans.

The European Union and US Environmental Protection Agency are currently completing their latest reviews.

The New Zealand EPA has indicated it will take a lead from these reviews, and notes that the current opinion of the relevant US, Canadian, EU and Australian regulatory authorities is that glyphosate is safe to be used as a herbicide.

New Zealand EPA update August 2016

The New Zealand EPA released the findings of their report Review of the Evidence Relating to Glyphosate and Carcinogenicity on 11 August 2016. The report found that glyphosate is unlikely to be carcinogenic and should not be classified as a mutagen or carcinogen under the Hazardous Substances and New Organisms Act 1996.

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