Pest Plants

Pest Plants: Recognise, Report, Remove, Restore

The Okura Bush and Karepiro Forest are threatened by aggressive invasive pest plants. Invasive weeds are a growing threat to the bush. New Zealand has a huge list of exotic plant species that have escaped from gardens into the wild and at least 400 are regarded as serious environmental pests. These are the ones that can invade, transform and destroy native ecosystems.

Controlling them when they are small is easy and cheap. If they are left to grow, they can spread across your property onto your neighbours’ gardens and to nearby reserves, smothering our native bush and destroying the habitat of native wildlife.

The ‘do nothing option’ would see large parts of the forest and surrounding areas taken over by pest plants which would eventually kill off the native plants in the bush. Some pest plants, such as privet, moth plant and woolly nightshade, can also be bad for our health

We have volunteers (and through grants we can sometimes engage specialist contractors) that are involved in regular environmental restoration activities but these initiatives are limited due to time and budget constraints. The majority of these pest plants are garden escapees The first line of defence is to involve the public and gardeners to identify these plants and to assist to eradicate them. Please assist by:

  • Recognise pest plants by reading and using the resources below, or download the excellent app iNaturalist.NZ;
  • Spread the word! Share your knowledge with neighbours, family and other keen gardeners;
  • do not propagate or share pest plants
  • remove these pest plants from gardens. Ensure that pods and seed heads are securely disposed of in landfill;
  • look around and remove from your neighbourhood, road reserves and parks or where you may encounter them.
  • Restore our native wildlife by planting native trees and shrubs, which will feed tūī, kererū and other native birds and wildlife all year round and make your neighbourhood a more attractive place to live. Native planting after pest plant control also helps to prevent those sites from being colonised by other weeds.
  • Join one of our environmental restoration initiatives to remove pest plants. If you are not living close to The Okura Bush, search for similar groups in your area, every effort is valuable.

For more information see
Pestfree Kaipatiki
Weedbusters

Although weeds are everywhere and it is an ongoing task to get rid of it in gardens, for FoOB the urgent priority is to get rid of pest plants that can spread into the bush where it is much more difficult to control.

Twelve of the worst weeds around Okura Bush

(and a calendar to remove them but you can do it all year round…)

January:
Moth plant – flowering at this time, distinctive pods some other times of the year
February:
Blue morning glory – flowering or just finishing flowering
March:

Madeira vine – flowering
April:
Pampas grass – flowering
May:
Woolly nightshade – not flowering but easily recognised
June:
Wild ginger – not flowering but easily recognised and can control or dig out in winter

July:
Agapanthus – not flowering but easily recognised by most people and it looks nice while flowering so propose promoting control before it flowers and seeds
August:
Montbretia – not flowering but easy to pull out the bulbs when the soil is wet in winter.

September:
Loquat – bearing fruit that is spread by birds into the bush they are easily identified this time of the year
Climbing asparagus – tubers can be dug out easily if doing manually
October:
Jasmine – spring flowering and same as English ivy
November:
Japanese honeysuckle – flowering or about to flower
December:
Chinese and tree privet – flowering at this time

Moth Plant

Moth plant pods and flowers

Moth Plant

Moth plant is a particularly nasty pest plant as it spreads so quickly and smothers our native bush. It is poisonous to people and its sap can irritate the skin. The nectar is poisonous and it also kills off bees and Monarch butterflies! From January, the vines form bell-shaped creamy coloured flowers, occasionally with pink streaks.

Over the coming months, these flowers will turn into large, green, pear-shaped pods, which each release thousands of fluffy parachute seeds into the air infesting more gardens, parks and bush. So now is the time to take action!

If you notice moth plant on your property or in your nearby parks, please follow these guidelines:
● Report the weed using the EcoTrack.nz app
● We recommend joining the Facebook group Society Totally Against Moth Plant (STAMP) and report it there.
● Dig out any small seedlings, including roots
● For larger vines, find the stem where it goes into the ground, cut it near the base and immediately paste a thin smear of Met gel onto the cut stem (can purchase at any hardware store or garden centre)
● Dispose of the flowers, roots and any pods in your rubbish bin to go to landfill, securely tied inside a plastic bag – to stop it spreading to other areas. Unfortunately, they can’t be composted.
● Leave the vine hanging in the tree to die
● Talk to your neighbours and encourage them to take action too!

Cotoneaster

Cotoneaster berries and hedge

Cotoneaster

Popular as a hedge, an arching, spreading, evergreen shrub usually less than 3m tall. Clusters of 15-60 small white flowers appear from October to January followed by distinctive scarlet berries (4-7 mm diameter) from February to August.

It is a direct competitor with native shrub species and can form pure stands in native shrubland, bluffs, and steep and rocky habitats. Produces large amounts of highly viable seed, matures quickly and is long-lived. Birds distribute seeds widely from sources of infestations which include gardens and hedges

Take action as soon as possible:
● Report the weed using the EcoTrack.nz app
● Hand pull small infestations.
● For larger stems, cut near to the ground and immediately paste a thin smear of Bamboo Buster on the cut stem – can be purchased at most garden centres or hardware stores.
● As the weed spreads vegetatively from stem fragments, hang up cut vine well off the ground and leave up high to dry out.
● Put all other cut waste inside a securely tied plastic bag and dispose in the rubbish bin to go to landfill
● Talk to your neighbours and encourage them to take action too!

Madeira Vine

Madeira vine

Madeira vine


This pesty creeper has reddish stems with small irregular ‘warty’ aerial tubers. The leaves are heart shaped, glossy, clammy to the touch, and arranged alternately on the stems. It’s flowering about now, with lots of slender, drooping, cream-coloured flowerheads about 18 cm long.

Madeira vine forms dense long-lived infestations that smother native plants and dominate the bush at medium to high canopy level. It can even topple small trees.

Take action as soon as possible:
● Report the weed using the EcoTrack.nz app
● Pull out roots
● Collect all aerial tubers
● Put all parts in a securely tied black plastic bag and leave to ‘cook’ in the sun
● For larger stems, cut near to the ground and immediately paste a thin film of Met Gel on the cut stem – can be purchased at most garden centres or hardware stores.
● Follow up will be required as it is incredibly persistent.
● Talk to your neighbours and encourage them to take action too!
● Report madeira vine on Council Land to: aucklandcouncil.govt.nz/report-it

Pampas

Pampass

Pampas

This invasive grass forms in clumps up to 3 metres tall. Sometimes mistaken for our beautiful native toetoe, the leaves of pampas are razor-sharp hence its common name, ‘cutty grass’. Unlike toetoe’s drooping creamy-coloured flowers, pampas produces flowers from February to April that are erect, dense and uniform – generally white, pinkish or purplish in colour.
…. not to be confused with native toetoe

toetoe

Native NZ toetoe

Pampas is a serious threat to some natural areas like sand dunes, stream banks and coastal cliffs where it can completely replace native plants. It is also a problem on roadsides, as it reduces visibility. Pampas can be a fire risk and harbours animal pests such as rats, mice, rabbits and possums.

Take action as soon as possible before the seeds form next summer:
● Report the weed using the EcoTrack.nz app
● For young plants, the best option is to loosen the soil and pull them out. A digger or bulldozer can be used to remove big plants.
● To avoid nasty cuts, wear gloves and protective clothing.
● If using herbicides, they’re most effective on pampas during spring and early summer before the plants are flowering. Slash plants about 30cm from the ground and spot spray the regrowth with glyphosate 15ml/l (plus penetrant). Ask at your local garden centre, hardware store or RD1 farm supply store. Always wear appropriate personal protection equipment (PPE) and read the manufacturer’s label for guidelines and recommendations.
● For more experienced volunteers with Growsafe qualifications, other herbicide methods may be used.
● Leaf matter can be left on site, acting as mulch and shading out the seed bank.

Woolly nightshade

Woolly nightshade

Woolly nightshade

This small tree grows rapidly to over 8 metres, often forming dense stands that crowd out native seedlings. It also produces toxins that poison the soil and prevent native plants regenerating. Purple flowers are followed by clusters of green-yellow berries, which are spread by birds to new locations.

Woolly nightshade is also bad for our health – the dust from the plant can irritate eyes, skin, nose and throat and the berries are toxic.

Take action as soon as possible:
● Report the weed using the EcoTrack.nz app.
● Wear personal protection equipment, such as a mask and gloves.
● Hand pull small infestations.
● For small to medium-sized stems, cut near to the ground and immediately paste a thin film of cut and paste Picloram gel or Bamboo Buster on the cut stem – can be purchased at most garden centres or hardware stores. Always read the manufacturer’s label for guidelines and recommendations.
● For large trees, cut two rings 20-30cm apart around the base of the trunk. Remove the bark between each ring, then apply a thin film of Bamboo Buster around the exposed part of the tree. The gradually dying tree will provide canopy cover for emerging native plants.
● Talk to your neighbours and encourage them to take action too!

Wild ginger

Wild ginger

Kahili ginger

Wild ginger, also known as Kahili ginger, grows up to 2 metres tall with large wax-covered leaves. It forms dense, long-lived clumps that shade out the understorey and prevent growth of native seedlings and forest regeneration. It has red and yellow flowers that can produce hundreds of seeds.

Take action as soon as possible:
● Report the weed using the EcoTrack.nz app.
● Hand pull small seedlings, but only if you can remove all root fragments, as they will regrow if left.
● For medium to large plants, use a pruning saw to cut the stem close to the ground. Aim to make the cut level (so that the herbicide can have the best contact with the freshly cut stump). Apply a thin film of MetGel or Picloram gel to the stump. A thin film is all you need to prevent regrowth.
● Follow up in three months to ensure all wild ginger plants have died.
● Dispose of the flowers, and any rhizomes and roots in your rubbish bin to go to landfill, securely tied inside a plastic bag – to stop it spreading to other areas. Alternatively, they can be put inside a barrel of water (lid on) and will rot down within 1-2 years.
● If you don’t have the time or means to cut down the plants, removing the flowers will help to prevent the seeds to be spread by birds. A fun activity for the younger members in the family too!
● Talk to your neighbours and encourage them to take action too!

Agapanthus

Agapanthus

Agapanthus


Agapanthus forms dense umbrella-like clusters with white root rhizomes and dark green leathery leaves that prevent and displace native species from regenerating. Its purple flowers are visible from December to February and they produce thin, papery, black seeds that are dispersed by wind or water. The plant can also spread from fragments of the root rhizome in contaminated soil.

Take action as soon as possible:
● Report the weed using the EcoTrack.nz app.
● Dig out small infestations trying to remove most parts of the root rhizomes – Agapanthus can regrow from rhizomes that are left in the ground.
● For medium to large infestations, use a pruning saw, spade or another hand tool to cut the stem close to the ground. Quickly apply a thin film of MetGel onto the cut stump or rhizomes.
● Follow up in three months to reapply herbicide and ensure all regrowth has died.
● Dispose of the flowers and any rhizomes and roots in your rubbish bin to go to landfill, securely tied inside a plastic bag – to stop it spreading to other areas.
● Talk to your neighbours and encourage them to take action too!

Montbretia

Montbretia

Montbretia

Montbretia is an invasive perennial plant that grows from underground corms. It is a horticultural hybrid which was developed in France for ornamental purposes in the 1880s. Since then, it has escaped into the wild and spread rapidly
The biodiversity of ecosystems can be significantly affected by an infestation of Montbretia. Competes with groundcovers and small shrubs and inhibits the establishment of native plant seedings. Specialised low-growing species may be displaced, especially in riparian margins.
Take action as soon as possible:
● Report the weed using the EcoTrack.nz app.
● Dig out small infestations trying to remove most parts of the root rhizomes – it can regrow from rhizomes that are left in the ground.
● Spray (full leaf stage): glyphosate (10ml/L) + metsulfuron-methyl 600g/kg (4g/10L + penetrant).
● Talk to your neighbours and encourage them to take action too!

Climbing Asparagus

Climbing asparagus

Climbing asparaghus

Climbing asparagus is a scrambling vine that is capable of smothering and shading out seedlings, eventually creating thick mats throughout the understory and prohibiting indigenous forest regeneration. This vine is able to grow in shaded areas making it a high threat for invading native bush. The berries ripen from green to red-orange and the seed is spread by birds. It can also be spread by dumping of garden waste.

Take action as soon as possible:
● Report the weed using the EcoTrack.nz app.
● Dig out small infestations trying to remove all parts of the root rhizomes – climbing asparagus can regrow from rhizomes that are left in the ground.
● If using herbicides, they’re most effective in spring and early summer before the seeds have ripened. Hand pull any climbing vines off non-target plants and seedlings before spraying. Spray with glyphosate 20ml/l (plus penetrant). Always wear appropriate PPE and follow the instructions
● Follow up in three months to reapply herbicide and ensure all regrowth has died.
● Dispose of seeds, rhizomes and roots in your rubbish bin to go to the landfill, securely tied inside a plastic bag – to stop it spreading to other areas.
● Talk to your neighbours and encourage them to take action too!

Loquat

Loquat fruit and flowers

Loquat fruit and flowers


Loquat is an evergreen tree with oval, leathery leaves that are dark green and glossy above and grey, thinly hairy below. White or ivory 5-petalled flowers (8 x 4 mm, Apr-Aug) are followed by pear-shaped to roundish fruit (<50 x 35 mm, Oct-Dec) with yellow skin covered in downy hair. Seeds are large and brown and spread by birds, especially kereru, and humans, Loquat forms tall, dense stands which replace native low canopy and mid-tier species
  • Easy to kill, or Report the weed using the EcoTrack.nz app.
  • Hand pull or dig small seedlings (all year round). Leave on site to rot down.
  • Cut down big plants close to ground (all year round). Leave on site to rot down.
  • Large trees: ringbark or drill and fill with herbicide (all year round), leave to die standing.

Jasmine

Jasmin flowers and vine

Jasmin


Jasmine is a climbing vine that is capable of smothering and shading out seedlings. It is also shade tolerant, eventually creating thick mats throughout the understory of indigenous forest and prohibiting natural regeneration. Jasmine is mainly spread by fragments dumped in green waste that quickly grow into large infestations. It usually flowers around springtime and it’s best to start controlling it now.

If you notice jasmine on your property, take action as soon as possible:
● Report the weed using the EcoTrack.nz app.
● Dig out small infestations, trying to remove all parts of the root system – Jasmine can regrow from stem fragments that are left in the ground.
● Hand release off native trees where possible. Make a cut at the base of the stem and apply a thin film of Met Gel to both ends of the cut stem.
● Large vines can be left on the tree after applying Met Gel to both ends of the cut stem.
● For large infestations and ground cover, foliar spray with 0.5g/l metsulfuron and 2 ml/l penetrant. Always wear appropriate Personal Protection Equipment and read the manufacturer’s label for guidelines and recommendations. Talk to our Restore Hibiscus & Bays Ecological Restoration Advisor for further guidance.
● Follow up in three months to reapply herbicide and ensure all regrowth has died (mature jasmine infestations usually need multiple applications).
● Talk to your neighbours and encourage them to act too!
● Download a printable leaflet/poster about jasmine and other pest plants from the Restore Hibiscus & Bays website: Pest plants resources
Also see Weedbusters: Jasmine

Ivy

English Ivy

English Ivy

English Ivy

English ivy is a fast-growing, creeping vine with hairless, dark green or green/white leaves. Roots and stems can reach up to 30 metres, strangling host trees and smothering the understory and prohibiting native forest regeneration. Ivy is spread by birds dispersing the seeds as well as by dumping of garden waste, as it can regrow from stems.

German Ivy

German Ivy

German Ivy


Fast-growing and dense smothering habit. Distributes many wind-blown seeds long distances.

Cape Ivy

Cape ivy

Cape ivy


Produces many long-lived seeds that are dispersed a long way from parent plants. Moderate growth rate and layering stems, scrambles over shrubs and ground, forms dense, tall thickets. Tolerates salt, wind, drought, semi-shade and damage.

If you notice ivy on your property, take action as soon as possible:
● Report the weed using the EcoTrack.nz app.
● Dig out small infestations, trying to remove all parts of the root system – ivy can regrow from stem fragments that are left in the ground.
● Hand release off native trees where possible. Make a cut at the base of the stem and apply a thin film of MetGel to the cut stem

Blue morning glory

Morning glory

Morning glory

The purple tubular flowers of this tall-growing creeper may look pretty right now, but it’s extremely fast growing and can smother native vegetation as ground cover, as well as climbing up native trees. If left unchecked, morning glory can kill off all other plants in a patch of land until it is the only surviving species!
Take action as soon as possible:
● Report the weed using the EcoTrack.nz app
● Hand pull small infestations.
● For larger stems, cut near to the ground and immediately paste a thin smear of Bamboo Buster on the cut stem – can be purchased at most garden centres or hardware stores.
● As the weed spreads vegetatively from stem fragments, hang up cut vine well off the ground and leave up high to dry out.
● Put all other cut waste inside a securely tied plastic bag and dispose in the rubbish bin to go to landfill. Alternatively, it can be put inside a composting weed bag.
● Talk to your neighbours and encourage them to take action too!

Periwinkle

Periwinkle flower and growth

Periwinkle

Another popular garden ground cover that escaped and is causing problems. Creeping, layering habit allows it to form dense, long-lived stands. Smothers ground in open or shady conditions, prevents the seedlings of native species from establishing, and opening up habitats so that they are more vulnerable to weedy vines and grasses.

Difficult to eradicate, take action as soon as possible:

  • Report the weed using the EcoTrack.nz app
  • Dig out small sites. Dispose of plant material at a refuse transfer station or burn. Check for regrowth.
  • Spray (all year round): glyphosate (20ml/L + penetrant). Requires constant follow up.
  • Mowing: For level, easily accessed land, mow with lawnmower on very low setting, 2-3 times a year. As it regrows, follow up by grubbing remaining roots with grubber or shovel. Leave on site to rot down. Takes 1-2 years to eradicate.
  • Smothering: use black plastic or weed mat. Cover sites as they are, or rake into big rolls and then cover (6+ months). Hand-remove surviving plants.
  • For larger stems, cut near to the ground and immediately paste a thin smear of Bamboo Buster on the cut stem – can be purchased at most garden centres or hardware stores.
  • As the weed spreads vegetatively from stem fragments, hang up cut vine well off the ground and leave up high to dry out. Put all other cut waste inside a securely tied plastic bag and dispose in the rubbish bin to go to landfill. Alternatively, it can be put inside a composting weed bag and left for a couple of months to decompose
  • Talk to your neighbours and encourage them to take action too!

Privet

Tree privet

Japanese privet or tree privet

Small-to-large evergreen, hairless tree or dense shrub with distinctive lumpy warts on the stems. Dark green leaves are glossy on the top surface and arranged in opposite pairs on the stems. Tiny fragrant, creamy flowers make up flowerheads (Nov-Mar) and are followed by bluish or purplish-black berry-like fruit (6 x 5 mm)

Produces many highly viable seeds in berries that are widely dispersed by birds. Fast-growing, long-lived and forms very dense, tall stands. Forms dense carpet of seedlings on the forest floor and grows through understorey to dominate and replace canopy trees in most forest types. Poisonous berries may impact on native fauna, especially insects.

Chinese privet

Chinese privet


Shrub or small tree (<5+ m), evergreen with distinctive warty lumps on stems and densely hairy shoots. Oval, dull green leaves (25-60 x 12-25 mm) occasionally have wavy edges. Loose drooping clusters of small, tubular and very fragrant white flowers with tiny mauve anthers (Jul-Mar) are followed by round, green berries that mature to dull purplish-black. What can I do to get rid of privet?
  • Pull or dig seedlings (all year round). Leave on site to rot down.
  • Cut and paint stump (within 15 minutes of cutting): glyphosate (200ml/L) or metsulfuron (5g/L + penetrant) or picloram gel.
  • Frilling: make deep cuts into the sapwood at regular intervals around the base of the tree, taking care not to ring-bark the plant, immediately saturate the cuts with metsulfuron (5g/10L + penetrant) or picloram gel.
  • Injection method: Drill sloping holes into the sapwood at regular intervals around the tree, immediately saturate with metsulfuron (5g/10L + penetrant) or a product containing 100g picloram+300g triclopyr/L (undiluted).
  • Spray (spring-autumn): metsulfuron (5g/10L + penetrant).

What can I do to stop it coming back?
Untreated stumps resprout. Reseeds profusely in bared areas. Follow up 6-monthly, easiest to spot during spring flowering. Don’t replant until seedling regrowth ceases, as privet will grow through groundcover.

Handy links and further reading

Identifying weeds – DOC
Weedbusters
Pest Free Kaipatiki Pest Plants
NZ Weeds – Massey University
Restore Hibiscus and Bays/ Pest Plants

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