Wellington Regional Council

These introduced species can threaten our region’s natural environment, recreational activities, and primary industries.

These plants can be just as harmful to our environment as pest animals. They can outcompete or smothering native plants, dry wetlands and rivers, reduce habitats for native animals, and grow rapidly in waterways. Some of these species are also harmful to agricultural land and livestock, affecting grazing land and productivity. They can be moved between farms on vehicles and equipment.

There are many plant pests in New Zealand but the three of great concern at the moment are:

Chilean Needle Grass

Chilean Needle Grass is a tall, tufted perennial tussock that can grow up to one metre in height. It produces seeds from three points on the plant: the panicle seed, mid-stem seed at the leaf joins and at the base of the plant. Panicle seed is the most obvious and is usually present November-January and, when conditions are suitable, March-May.

The seeds of Chilean Needle Grass can cause significant damage to stock. The needle-sharp tip and a tail mechanism that allows it to drill through animal fleece and into muscle. This mean that highly contaminated fleeces are virtually worthless and animal carcasses are downgraded because they require additional trimming to remove damaged meat.

Alligator Weed

Alligator weed is a fast-growing weed that can grow on land and in water, where it forms floating mats. It can be difficult to identify as it is a low-growing perennial which can be confused with other similar looking plants such as Primrose Willow and Willow weed. Alligator weed has long horizontal stems and can be up to 10m long. The steam are hollow and often reddish in colour. Coverage can be very pact when growing in clumps on land and much larger when growing as floating mat on water.

It can double in area in less than 2 months, clog waterways and drains. It can out-compete pastures and crops, affecting farm productions and profit and although some stock will set it, alligator weed is usually toxic and can cause blindness and other health problems.

Nassella Tussock

Nassella Tussock is a perennial tussock grass which grows up to 70cm high and 80cm wide and forms dense clumps. The stem is swollen just above ground level – like a shallot. Other similar looking tussocks have purplish colouration at their leaf bases. Light green or yellowish-green leaves are thin and tightly rolled; they do not break when pulled. When fingers are run down the leaf, they feel needle-like and very tough. Plants usually flower between October and early summer when they have a purplish tinge. Flowering stems can be up to 1 m tall.

Nassella tussock can be seriously invasive, completely dominating low-producing grassland. Pasture carrying capacity can be significantly reduced because the leaves are unpalatable and indigestible. Because of its poor nutritional quality, sheep can lose condition on infested pastures. If forced to eat tussock, they will lose weight and can die as they cannot properly digest the leaves. Nassella tussock seeds can contaminate, and damage fleeces and hides of sheep, adding to production losses.

Luckily, these plants haven’t established in the Wellington Region like they have in other parts of the country. The Great Wellington council would like to keep it that way.

For more information go to https://www.lifestyleblock.co.nz/lifestyle-file/running-the-farm/weeds or https://www.weedbusters.org.nz/

If you think you have spotted a pest plant, contact Ag Pest This email address is being protected from spambots. You need JavaScript enabled to view it. or your local council to help you identify, and potentially remove it, it for free.

Northland – Pest Hub

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Waikato - This email address is being protected from spambots. You need JavaScript enabled to view it.

Manawatu - horizons

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Tasman – Pests and Weeds

Canterbury – Plant pests

Otago- - Plant Pests