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Plant PestsTipu Orotā

We provide information on the many plant pests that cause serious harm to the environment or economic loss to agriculture in Hawke's Bay.

What is the problem?

A large number of introduced plant species have naturalised in Hawke's Bay, to the extent that we have more introduced plants growing wild than our native species.

Many of these are considered weeds, but some cause serious harm to the environment or economic loss to agriculture. These serious weeds are called 'plant pests' and Hawke's Bay Regional Council has management plans in place, developed with community input, to meet the requirements of the Biosecurity Act 1993.

The Strategy's objectives are to:

  • reduce the density and extent of plant pests,
  • increase awareness of the public of the need to recognise and control these pests, and
  • ensure that plant pests listed in the strategy are not imported into the region, sold or distributed.

Chilean Needlegrass is one of the most serious plant pests in Hawke’s Bay and the Regional Council is involved in a nationwide campaign to limit the spread.

What’s a weed?

A weed may be described by gardeners as “a plant in the wrong place” but many weeds can have serious impacts on native bush, animals, pasture and people’s lifestyles. A good reference for identifying weeds is the Weedbusters website.

All plant pests are banned from sale, propogation or distribution under the Biosecurity Act 1993.

What the Regional Council can do to help

Biosecurity Plant Pest Officers from the Hawke's Bay Regional Council can help identify invasive, unusual or unwanted pests on your property.

Officers can also advise on the best methods of control of plant pests and can help formulate management plans. This might involve the use of biological controls, chemical spray control, or non-chemical controls such as stock management, pasture management and mechanical methods of pest removal.

What you can do to help

​Control all plant pests on your property

Destroy any plants shown in this web site that are on your property, and as they appear in future.

Dispose of plant pests safely

The best way to dispose of unwanted plant pests is to burn, compost, or dispose of them at an approved landfill or transfer station for deep burial. Root fragments, cuttings and seed heads can rapidly establish new plant pest infestations if they are dumped in areas such as native bush, stream banks, and along roadsides. They are also dispersed by birds, animals, wind and water and in the right conditions grow quickly, smothering native vegetation.

Prevent the spread of new plants

From time to time plants come into the region which quickly establish and can become plant pests.

​We rely on Hawke's Bay residents to be our eyes and ears looking out and reporting unusual organisms so we can respond immediately. Whether you are a landowner, lifestyle property owner or urban resident, there are plant pests that will require dealing with at some time or another.

Find out more about specific plant pests in our information sheets.

If you would like help with a pest control problem, or wish to report anything you think our Pest Control team should know about you can do so on our Fix It page.

 

Image Gallery

Hover over the image for plant names.

Plant pests & management programmes

The plants listed below are classified as pests. Each plant falls in to one of the following management programmes:

Sustained control - To provide for ongoing control of the subject, or an organism being spread by the subject, to reduce its impact on values and spread onto other properties.
Site led - The subject, or an organism being spread by the subject,b that is capable of causing damage to a place is excluded or eradicated from that place, or is contained, reduced, or controlled within the place to an extent that protects the values of that place.
Eradication - To reduce the infestation level of the subject, or an organism being spread by the subect, to zero levels in an area in the short to medium term.
Exclusion - To prevent the establishment of the subject, or an organism being spread by the subject, that is present in New Zealand but not yet established in an area.
Progressive containment - To contain or reduce the geographic distribution of the subkect, or an organism, being spread by the subject, to an area over time.

Common name Scientific name Programme Description
African feather grass Pennisetum macrourum Eradication What does it look like? It is a robust perennial grass that forms dense tussocks up to 2m high. It has yellow and purple flowers that come out from November to April in a narrow cylinder with barbed bristles.
Why is it a problem? It tolerates a range of environmental conditions and out-competes other plants. It can cause floods in waterways. Its seeds can be spread by water and machinery.
Alligator weed Alternanthera philoxeroides Exclusion What does it look like? Alligator weed lives both on land and in water. Its roots are found in the water margins, but the green, waxy leaves and clover-looking flowers float and spread across the water surface. It prefers temperate climates and is found in still or slow-moving water bodies, including lakes, streams, and drainage channels.
Why is it a problem? It is hardy and out-competes other plants, and tolerates a range of environmental conditions.  Alligator weed doesn’t set viable seed in New Zealand, but reproduces vegetatively from stem nodes and root fragments which are easily spread.
Apple of Sodom Solanum linnaeanum Progressive containment What does it look like? It is a spiny, woody perennial shrub which can grow over 1.5m. It has prickly leaves, and mauve or violet flowers from September to May, and produces berries that turn from green and white to black.
Why is it a problem? It is an invasive plant and is poisonus to humans. Birds spread its seeds.
Australian Sedge Carex longibrachiata Progressive containment What does it look like? It is a perennial tussick that can reach 1m high. It has flowers are grouped in spikes that come out from October to February, and has a small triangular seed.
Why is it a problem? It forms dense stands that exclude other pasture species and is not palatable to stock. Animals and machinery spread the seed.
Bathurst bur Xanthium spinosum Sustained control What does it look like? It is a spiny, woody, annual that grows up to 1m tall. It produces fruit that are small oval burs covered with slender hooks and inconspicuous flowers.
Why is it a problem? Burs can degrade the quality of wool, and the seeds are posinous to livestock. Animal wool or hair and machinery can spread the seed.
Blackberry Rubus fruticosus agg Sustained control What does it look like? It is a prickly, scrambling perennial shcrub with thorny stems up to 8m long. The berries change from green to a dark red or black when ripe.
Why is it a problem? It grows to form a thicket which can harbour pests such as rabbits and possums. It can impede water flow, be a fire hazard, and entangle sheep. Birds spread the seed.
Cathedral bells Cobaea scandens Eradication What does it look like? Cathedral bells is a fast-growing evergreen climbing vine that can grow to 6m tall. It has dark green leaves, with twining tendrils and bell-shaped flowers which are green when young but purple when mature. The 'fruit' are hard, oval capsules 5-8cm long that hold seeds.
Why is it a problem? Cathedral bells can form a dense canopy that out-competes desirable plants by smothering them and is tolerant of a range of soil and light conditions. It seeds well. 
Chilean needle grass Nassella neesiana Sustained control What does it look like? Chilean needle grass is an erect, tufted perennial grass that can grow up to 1m in height if left ungrazed. Chilean needle grass is most easily identified from October to March, when it is seeding. Seeds have a sharp needle like tip with a long twisting awn and are reddish purple in colour early in the seeding period (November), later drying to a golden brown colour (December, January). Chilean needle grass typically grows in dry, sunny areas.
Why is it a problem? Chilean needle grass is an invasive weed that out-competes productive pasture grasses and takes over large areas if left uncontrolled. Its seeds have a sharp, needle like tip which attaches easily to stock and can penetrate skin and muscle. This can cause painful abscesses for the animal, and can lead to downgrading of pelts, meat or wool. The seed can also injure horses and dogs. It is unpalatable to stock when it is seeding (November to January), reducing the stock carrying capacity on a property. The seed is sharp, and spreads by attaching itself to anything that brushed past the plant, including animals, people, vehicles, machinery and equipment, soil and contaminated feed.
Cotton thistle Onopordum acanthium Progressive containment What does it look like? It is a biennial plant that can grow up to 3m tall, with spiny and hairy leaves. The flower is a lavendar globe that comes out in summer.
Why is it a problem? It is drought resistant, can spread rapidly, and is adaptive to a range of environments. It can injure sheep's wool. It is difficult to eradicate.
Darwin's barberry Berberis darwinii Progressive containment What does it look like? Darwin's barberry is an evergreen spiny, yellow-wooded shrub that can grow up to 4m tall with woody stems and needle sharp leaves. Hanging clusters of orange flowers appear from July to February followed by dark purple berries.
Why is it a problem? It lives for a long time, can tolerate a range of conditions, and out-competes other plants. It seeds well. 
Goats rue Galega officinalis Eradication What does it look like? It is a perennial woody herb that can grow up to 1m tall, usually growing into dense clumps with tall stems. Its flowers a lilac or pink and grow in bunches on spikes 30cm or longer.
Why is it a problem? It is unpalatable and toxic to stock, and out-competes other plants.
Gorse Ulex europaens Sustained control What does it look like? It is aspiny perennial shrub up to 4m tall with conspicuous yellow flowers.
Why is it a problem? It can spread rapidly, can trap wooly animals, and has seeds that are viable for up to 80 years.
Japanese honeysuckle Lonicera japonica Progressive containment What does it look like? It is a perennial climbing vine with flowers that change from white to yellow when the come out in September to May. It has egg shaped black berries.
Why is it a problem? It can smother young trees and completely cover them from sunlight. It is particularly damaging to regenerating bush.
Mashwort Nymphoides geminata Exclusion What does it look like? Marshwort is a bottom-rooted perennial water lily-like plant.  It has long stems, which grow up to several metres long.  The stems lie just beneath the water surface, producing groups of leaves, roots, and yellow flowers. It grows in still or slow-moving water bodies including lake margins, streams, wetlands, and drains.
Why is it a problem? It colonises shallow water and can out-compete other lily species.
Nassella tussok Stipa trichotoma Progressive containment What does it look like? It is a perennial, tussock like grass with dense fibrous tough roots, up to 0.5m high and 1m across with drooping leaf. It flowers from October to December with purple flowers.
Why is it a problem? This tussock can rapidly dominate grasslands smothering them and is unpalatable to stock. In grain and small seed growing areas its presence means that the products can not be used domestically or for export.
Nodding thistle Carduus nutans Sustained control What does it look like? It has spiny leafed annual or biennial up to 1.5m tall, dark green upper leaves with irregular toothed lobes, flowers 'nod' at right angles to stem when mature. It's flowers a purple and has heavy seeds.
Why is it a problem? It forms dense clumps which smothers pasture, and its presence in seed can reject crop for export.
Noogoora bur Xanthium strumarium Exclusion What does it look like? Noogoora bur is a fast growing summer plant that can grow to 2.5m high and has spiny egg-shaped burs that contain seeds. The leaves are dark green and have purple veins. It likes fertile soils close to water and usually grows on arable land and can be found in riparian areas.
Why is it a problem? Noogoora bur contains chemicals that can impede the growth and germination of neighbouring plants. It produces large quantities of seeds that germinate into a fast growing and highly competitive weed that can cause significant losses in many crops.The seeds are contained in the burs which spread by attaching to animals, clothing and agricultural machinery. 
Old man's beard Clematis vitalba Progressive containment What does it look like? It is a deciduous, perennial vine growing up to 5m per year, leaf made up of five leaflets on each spike. It's creamy white flowers come out from December to May.
Why is it a problem? It can smother and kill plants it uses as support, can rapidly form a dense canopy, and prevents native seedlings from establishing.
Phragmites Phragmites australis Eradication What does it look like? It is an erect, rhizomatous, perennial grass, that grows 2-3m high. 40% of the plant is underground. It has brownish or purplish seed heads.
Why is it a problem? It grows in irrigation channels, drainage ditches, and poorly drained areas. It can block or at least seriously impede the flow of water.
Privet (Chinese and tree) Ligustrom sinence and lucidum Sustained control What does it look like? Chinese privet is a densely branched shrub up to 5m tall with 7cm long leaves, that produces clusters of white flowers and blu-black berries. Tree privet is a broad leafed shrub that grows up to 10m in height and produces clusters of white flowers and bllue-black berries.
Why is it a problem? It can cause severe allergic reactions in people who suffer from respiratory problems. Privet may also cause vomiting, diarrhoea, abdominal tenderness, gastroenteritis, skin irritations and dermatitis.
Purple loosestrife  Lythrum salicaria Eradication What does it look like? Purple loosestrife is a summer herb that grows 1-2m tall. It has narrow heart-shaped leaves and produces spikes of purple flowers that grow up to 25cm long.
Why is it a problem? It invades damp grounds, wetlands, and shallow water, out-competing native species, and can tolerate a range of conditions though is intolerant of salt water. Purple loosestrife reproduces by seed and regrowth, and germinates in moist, disturbed or open areas.
Ragwort Senecio jacobaea Sustained control What does it look like? It is a branched biennial or perennial plant 0.5 to 1.5m tall, bright yellow flowers, slightly furry leaves and purplish coloured stems. It has bright yellow flowers.
Why is it a problem? It invades pastures, suppresses crop yields, is toxic to cattle, and can harbour pests
Saffron thistle Carthanum lanatus Progressive containment What does it look like? It is a prickly bushy annual or biennial thistle with woody stems growing to about 1m high and yellow flowers
Why is it a problem? Infestations can form impenetrable stands. The plant is woody when mature and is very spiky. The dry sharp spikes get into wool and can cause injury when shearing or handling sheep
Senegal tea Gymnocoronis spilanthoides Exclusion What does it look like? Senegal tea is a hardy, semi-aquatic, perennial herb that forms rounded bushes up to 1.5m tall. White, clover-like flowers are present during summer. It grows in damp soils, wetlands, and streams and is usually rooted on the edge of waterways but can also survive and continue growing when completely inundated.
Why is it a problem? It grows very quickly, can rapidly cover water bodies with floating mats, and out-competes native species. Senegal tea can reproduce by seed or from broken stem or leaf fragments which grow roots. 
Spartina Spartina alterniflora Exclusion What does it look like? Spartina is an estuarine grass that grows in clumps up 1.5 metres tall. It grows in soft sediment in wave-protexted sites on the edges of estuaries and harbours, often with mangroves.
Why is it a problem? Spartina is an aggressive and persistent invader of inter-tidal mudflats that can lead to a loss of habitat for shorebirds, recreational fisheries and seafood. The dense growth of spartina traps sediment can eventually raise the ground level to a point where the area is no longer inter-tidal. 
Spiny emex Emex australis Eradication What does it look like? It is a low-lying and hairless annual herb, spreading from a dense rosette with a thick taproot. Leaves are dull green. Flowers are inconspicuous and are produced in clusters in between the leaves and stem. Fruits (or burrs) are in clusters, with each of the three-cornered burrs forming in the forks of the leaves.
Why is it a problem? Burrs can injure animals and humans and cause lameness. Wool can be down-graded when containing the seeds. Plants contains oxalate levels which are high enough to poison sheep if they eat substantial amounts.
Variagted thistle Silybum marianum Sustained control What does it look like? It is a conspicuous spiny annual/biennial thistle with a thick rosette of glossy dark green leaves with broad white patches around the veins on the upper surface. It has large purple flower heads.
Why is it a problem? It invades pasture, supresses crop yields, is toxic to cattle, and harbours pests.
Velvetleaf Abutilon theophrasti Progressive containment What does it look like? Velvetleaf is a summer-growing annual plant that can grow up to 1.5m tall or more. It has large, heart-shaped leaves and small yellow to yellow-orange flowers. It is found in wasteland, vacant lots, gardens and cultivated fields, especially maize and soyabean fields and along fence rows.
Why is it a problem? The spreading canopy of velvetleaf competes with other plants for sunlight, water and nutrients.  It also produces chemicals that inhibit seed germination and root growht of other plants. Velvetleaf reproduces from seeds, which are produced in large numbers and can survive for up to 50 years in soil.
White-edged nightshade Solanum marginatum Eradication What does it look like? White-edged nightshade is a perennial shrub with a prickly stem and green leaves with white veins. It has white flowers with round green fruit rupening to yellow or light brown seeds.
Why is it a problem? It displaces native species, and its fruit is toxic.
Wilding Conifers Pinus spp Progressive containment What does it look like? Wilding conifers or wilding pines can grow into tall, cylindrical trees up to approximately 70m tall and 2m in diameter.  Their leaves are needle like and they do not produce flowers but grow cones instead. Wilding conifers can grow in a range of habitats, including grasslands, shrublands, scrub riparian ecosystems and coastal dunes, from high altitudes to near sea level.
Why are they a problem? Wilding conifers are a major problem in areas where there is no native forest, such as above the bush line, in mineral belts and tussock grasslands, and also in native forests. Wilding conifers out-compete native species and modify the natural ecosystems so much that the unique New Zealand landscape is lost and native plants and animals are evicted or die.
Wooly nightshade Solanum mauritianum Progressive containment What does it look like? It is a shrub that grows up to 10m tall with greyish-green leaves. It has purple flowers and green berries which turn yellow when ripe.
Why is it a problem? It is aggressively invasive and very fast-growing plant which may form dense stands beneath which little else will grow. Because it is so invasive it can threaten native bush regeneration. People handling woolly nightshade may suffer nausea and irritation of the skin and respiratory tract.
Yellow bristle grass Setaria pumila Sustained control What does it look like? Yellow bristle grass has a hairless green to purple tinged stem, with seed heads appearing during summer.
Why is it a problem? Yellow bristle grass is an invasive weed that out-gorws and colonises pasture during the summer months. Cows don't eat it, which leads to low pasture utilisation and re-infestation.
Yellow water lily Nuphar lutea Eradication What does it look like? It is an aquatic perennial yellow flowered water lily with massive rhizomes, oblong dark green leaves up to 40cm long and 30cm wide.
Why is it a problem? Yellow water lily can totally invade slow running waterways or lakes, choking native plants and slowing water flow.
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