One of the major threats to the indigenous flora of the area is the number of exotic species which have become naturalised, encroaching and usurping native species from some specialised habitats, especially the dunes. In theory all exotic plants, once found in the wild, could be classed as weeds and, while many create no problem for native species some do, and this page will highlight some of those which are and some found in close proximity to the area which could develop to become pests.

This page, together with its external links, aims to provide a deeper insight into the challenges confronting the Estuary for those wishing to search of further information. For a hands-on experience a fortnightly work party undertakes weeding sessions on a Sunday morning, and it is a good way to learn of the problems and to gain experience at identifying problem species. There is also a Wednesday work party. If you are interested in helping with this important work, please use the contact form for further information.

Many of the problem species are escapees from gardens which prove to be rampant once outside and left to their own devices. While many are not serious pests there is something gardeners can do and that is to grow species that are not likely to be troublesome. A booklet produced by Weedbusters New Zealand can be downloaded here which gives some alternatives to a number of potential pest species.

The standard publication listing environmental weeds in Aotearoa New Zealand is produced periodically by the Department of Conservation, the latest is McAlpine KG, Howell CJ 2024 List of Environmental Weeds in New Zealand. 2024. Science for Conservation 340.

Not all species listed in the above publication occur in all regions and Horizons Regional Council produce their own Horizons Regional Council Regional Pest Management Plan 2017-2037. This goes into more detail and is well worth a read.

Currently there is work underway at producing a new Management Plan for the Estuary. Once this is complete, a link to the section on pest plants will be included here. A previous attempt at a pest plan titled Manawatu Estuary Weed Implementation Plan 2015 – 2020 was produced, although progressing no further than a draft, it still provides a comprehensive coverage of the problem.