Pest Plant Control

With over 300 pest plant species in our region, controlling these pests is a huge job. Our region’s biodiversity is threatened by pest plants which can choke lakes, degrade wetlands, collapse forest canopies, smother regeneration in natural areas, and invade alpine and tussockland. 

Horizons employs biosecurity staff across the region. They have primary responsibility for inspection, enforcement, advisory and monitoring activities. They're responsible for organising contractors to carry out control work on zero-density plants and enforcement work.

Under the Biosecurity Act Horizons produces and implements a Regional Pest Management Plan. The Plan is to prevent new incursions of pest plants and manage the impacts of those pest plants already established.

View the Regional Pest Management Plan 2017-37.

Contact the team

Report a pest or get advice

Not sure if you’ve identified a weed? Need to know how to deal with a pest? Our pest management team wants to hear from you. Our pest management role includes providing advice to the public. If you are having problems with pest animals or plants we can offer advice on control options.


A - Z of Pest Plants

The Weedbusters website has a fantastic A-Z of pest plants. If you're unsure of the species check it out. 

A-Z Pest Plants

Wilding Conifer Project

The Wilding Conifer Management Group includes; Horizons, the Department of Conservation, Forest companies, Bay of Plenty, Waikato and Hawkes Bay Regional Councils, Tasman, Marlborough and Queenstown Lakes District Councils, Environment Canterbury, Environment Southland, Land Information NZ, High Country Federated Farmers, Landcorp Farming, Royal Forest and Bird Society, and Scion. For more information on the Wilding Conifers Project check out Prevent The Spread.

Biological Control

Biological control or biocontrol has resulted in substantial pest plant management gains through the use of one living organism to control another. It has proven particularly useful for controlling widespread weeds that are well established, that are heavy seeders, or have large seed banks. Once the agents are well established there is generally no need to make further releases as the population disperses and becomes self-sustaining. However, it can take many years (decades even) for the population to build up to a point where it impacts substantially on the host plant.

It is worth noting that successful biocontrol does not usually eradicate its host. Success may mean a reduction of infestation size, vigour, or abundance into the foreseeable future. It should be viewed as a tool that complements other weed management options. Biocontrol may reduce population levels to a point where control using physical or chemical methods is minimised, or even unnecessary.

The biocontrol programme exists to carry-out releases of new and existing agents against entrenched pests, raise awareness of the programme and support research into new agents. For more information check out the Landcare Research website.