Check, Clean, Dry

The invasion of aquatic pests into Canterbury's waterways affects us all.  If you fish, whitebait, water ski, row, kayak or just swim, these water weeds can affect your success, safety and enjoyment of our waterways.  Water weeds ruin valuable ecosystems by inhibiting growth of native water plants and reducing likely spawning areas for many types of fish.

Some of the aquatic pest species present in New Zealand, exist within our region, but many of our lakes and rivers remain pest-free. To help keep it this way, it's important that equipment and vessels are properly cleaned and decontaminated before entering any Canterbury waterway. Remember high risk species are those that are microscopic. So even if you can't see it, if it's wet, it's a threat!

How to prevent aquatic weed invasions

CHECK

Check boats, trailers and anything else that was in the water, including your dog’s paws if your dog is in the water with you, for any plant material and remove it. Even if the plant appears dry and dead, it may still survive and start a new infestation. Leave debris at the site or, if you find any later, treat and dispose of it in the rubbish. Do not wash down drains.

CLEAN

Wash all equipment (eg, nets, machinery, footwear and clothing) thoroughly with an appropriate decontamination solution before putting it in any new water way.

DRY

If you can't clean your gear or animals, restrict use to a single waterway OR dry completely to the touch inside and out, and leave to dry for at least another 48 hours.

Particular attention needs to be given to those users who are moving between different waterbodies, catchments, regions and islands with the same vessels and/or equipment.

What else can I do to prevent aquatic weed invasions?

  • Do not throw any aquarium or pond material into waterways. Instead, put all unwanted pond material on the garden or compost - your small oxygen weed may become the next threat to native fish, birds and plants.
  • Do not give plants or plant parts away to others until you are sure that they are not a threat to our waterways.
  • Make wise decisions on how to avoid increasing nutrient levels in waterways from fertiliser. High levels of nutrients running into waterways tend to encourage vigorous growth of some weeds.

Guidelines for running a waterway event

If you're running an event in a Canterbury waterway, it's important to tell participants about the need to 'Check, Clean, Dry' equipment:

  • before entering a waterway;
  • before moving between waterbodies;
  • before leaving the area - especially from the South Island*.

This could be a condition of entry on your event registration form. Event signage and cleaning facilities, could also act as a useful reminder.

Environment Canterbury provide free portable cleaning equipment, which you can book for your event. Contact us on 0800 324 636 or email at biosecurity@ecan.govt.nz to use this or for further biosecurity related advice.

The Ministry of Primary Industries (MPI) also has more information on holding a waterway event.

Aquatic weeds of concern

Alligator weed (Alternanthera philoxeroides)

Alligator weed

 

Background

Alligator weed is native to South America. It apparently arrived in New Zealand accidentally in the 1800s via discarded ship ballast water. It has since spread throughout Northland and is found in parts of the Waikato, including the Waikato River, farms, market gardens and urban properties.

Description
  • Waterweed that creeps or floats on the water surface (stem tips grow upright).
  • Stems are hollow, green or red-tinged (up to 10m long).
  • Bright green, lance-shaped, waxy leaves grow opposite along the stem.
  • Fibrous roots.
  • Small, white flowers (December–February) grouped in a single clover-like flower head, held up by a tiny stalk at the stem tip.

Find out more about Alligator weed:

Why is it a problem?

Alligator weed is tolerant of shade, drought and poor drainage. It grows rapidly to form dense mats of vegetation that completely cover the water’s surface. These dense mats prevent native plants from growing, and degrade wetlands and waterways.

It spreads by stem fragments, so the smallest piece broken from this plant can potentially resprout and grow elsewhere. Fragments spread by dumped vegetation as well as water, livestock, machinery, boats, fishing equipment and soil movement.

Alligator weed is also an issue on land, especially as it can double its hold on an area in less than two months. It will out-complete pasture crops, negatively affecting farm production profits. While animals will eat alligator weed, it is toxic and can cause blindness and other health problems.

Control & Management

CHECK

Check boats, trailers and anything else that was in the water, including your dog’s paws if your dog is in the water with you, for any plant material and remove it. Even if the plant appears dry and dead, it may still survive and start a new infestation. Leave debris at the site or if you find any later, treat and dispose of it in the rubbish. Do not wash down drains.

CLEAN

Wash all equipment (eg, nets, machinery, footwear and clothing) thoroughly with an appropriate decontamination solution before putting it in any new water way.

DRY

If you can't clean your gear or animals, restrict use to a single waterway or dry completely to the touch inside and out, and leave to dry for at least another 48 hours.

What else can I do to prevent aquatic weed invasions?

  • Do not throw any aquarium or pond material into waterways. Instead, put all unwanted pond material on the garden or compost - your small oxygen weed may become the next threat to many native fish, birds and plants.
  • Do not give plants or plant parts away to others until you are sure that they are not a threat to our waterways.
  • Make wise decisions on how to avoid increasing nutrient levels in waterways from fertiliser. High levels of nutrients running into waterways tend to encourage vigorous growth of some weeds.
Management strategy

Alligator weed is an unwanted organism which is listed on the National Pest Plant Accord.  This means it is illegal to propagate, distribute or sell it within New Zealand.

If you think you have found Alligator weed in Canterbury, contact Environment Canterbury on 0800 EC INFO. Environment Canterbury will undertake control of this pest if it is found in Canterbury.

Didymo (Didymosphenia geminata)

The South Island is a controlled area for didymo. This makes it a legal requirement to clean all gear used in the water before going from one waterway to another.

Didymo

Background

Didymo is native in northern Europe and northern parts of America. Didymo was discovered invading waterways in waterways in the South Island in New Zealand in 2004.

Didymo is a type of algae (diatom) that is invisible to the human eye. When millions of these microscopic cells form a large colony, we can see didymo attaching to rocks and submerged plants by stalks that form a thick brown layer completely smothering a stream or lake bed. Preventing the spread of didymo relies on freshwater users cleaning their aquatic equipment between waterways.

In response to this reliance, the Ministry for Primary Industries (MPI) is engaging with freshwater users through the 'Check, Clean, Dry' awareness and behaviour change campaign.

Description
  • Algal bloom feels spongy and scratchy like cotton wool.
  • Attaches very securely to river stones and does not fall apart when rubbed between your fingers.
  • Beige/brown/white colour (not green).
  • If alive, didymo has no distinctive odour.
  • When not in bloom, water samples need to be taken for microscopic analysis as it is invisible to the naked eye at this point, but may still be present in the waterway.
Why is it a problem?

It is very easy to spread didymo cells (diatom). It takes only one didymo cell in a single drop of water for the algae to spread between waterways. Its primary spread pathway is via contaminated aquatic and fishing equipment between waterways.

Didymo blooms attach to rocks and submerged plants by stalks that form a thick brown layer completely smothering a stream or lakebed. Blooms can produce ‘rat tail’ shaped forms that turn white at the ends and appear similar to tissue paper.

Once established didymo blooms, it adversely affects water quality, aquatic invertebrates and fish stocks. Didymo blooms are a hazard for hydroelectric generation, agricultural irrigations and recreations pursuits.

Control & management

The South Island is a controlled area for didymo. This makes it a legal requirement to clean all gear used in the water before going from one waterway to another.

Didymo is an unwanted organism. This means it is illegal to propagate, distribute or sell it within New Zealand. Control methods for didymo are limited. Prevention is the main management of didymo spread. For specific decontamination methods visit www.mpi.govt.nz.

MPI want to keep a track of where didymo is present. If you think you have found didymo contact MPI’s pest-and-disease hotline 0800 80 99 66.

CHECK

Check boats, trailers and anything else that was in the water, including your dog’s paws if your dog is in the water with you, for any plant material and remove it. Even if the plant appears dry and dead, it may still survive and start a new infestation. Leave debris at the site or if you find any later, treat and dispose of it in the rubbish. Do not wash down drains.

CLEAN

Wash all equipment (eg, nets, machinery, footwear and clothing) thoroughly with an appropriate decontamination solution before putting it in any new water way.

DRY

If you can't clean your gear or animals, restrict use to a single waterway or dry completely to the touch inside and out, and then leave to dry for at least another 48 hours.

What else can I do to prevent aquatic weed invasions?

  • Do not throw any aquarium or pond material into waterways. Instead, put all unwanted pond material on the garden or compost - your small oxygen weed may become the next threat to native fish, birds, and plants.
  • Do not give plants or plant parts away to others until you are sure they are not a threat to our waterways.
  • Make wise decisions on how to avoid increasing nutrient levels in waterways from fertiliser. High levels of nutrients running into waterways tend to encourage vigorous growth of some weeds.
Management strategy

Didymo is an unwanted organism.  This means it is illegal to propagate, distribute or sell it within New Zealand.  Control methods for didymo are limited.  Prevention is the main management of didymo spread. For specific decontamination methods visit www.mpi.govt.nz.

Preventing the further spread of didymo relies on freshwater users cleaning their aquatic equipment between waterways.  In response to this reliance, the Ministry for Primary Industries (MPI) is engaging with freshwater users through the Check Clean Dry awareness and behaviour change campaign.

MPI want to keep a track of where didymo is present.  If you think you have found didymo contact MPI’s pest-and-disease hotline 0800 80 99 66.

Egeria (Egeria Densai)

Egaria

Background

Egeria is native to South America. It grows in fresh water. It is present in Waikato hydro lakes and scattered elsewhere in the North Island. It is only found occasionally in the South Island, so our aim is to prevent its spread in the Canterbury region. To help keep Canterbury free of Egeria, you should ‘Check, Clean, Dry’ by removing all plant debris from your aquatic equipment every time you enter or leave to go to a new waterway.

Description
Egeria can be confused with Canadian pondweed (Elodea) and Lagrosiphon.  Elodea, which is common, has smaller leaves arranged in groups of three around the stem, while Lagarosiphon has leaves arranged in a spiral around the stem and the leaves curve downwards. Egeria is larger than these two species and is the only oxygen weed in New Zealand with visible white flowers.
  • Egeria has dark green leaves, up to 40mm long and 2-5mm wide.
  • Leaves join onto the stems in groups of four or more.
  • Lower leaves may arise in groups of three.
  • Stems are multi-branched, 3mm in diameter and break easily.
  • Plants are usually totally submerged, but Egeria can grow right to the water surface and form a tangled mat.
  • Flowers have three white petals that emerge above the water.

Find out more about Egeria:

Why is it a problem?

Egeria is a long-living aquatic pest plant which grows quickly in most water types. It forms dense stands that shade out native aquatic plants destroying animal and plant habitats. When it rots, the plants degrade the water quality making it harder for other species to survive.

It grows from any stem fragment, making it easy to move to other waterways if people do not check and clean their contaminated clothing or equipment between waterways.  It is also very difficult to kill. All these factors make Egeria an invasive species.

Control & management

CHECK

Check boats, trailers and anything else that was in the water, including your dog’s paws if your dog is in the water with you, for any plant material and remove it. Even if the plant appears dry and dead, it may still survive and start a new infestation. Leave debris at the site or if you find any later, treat and dispose of it in the rubbish. Do not wash down drains.

CLEAN

Wash all equipment (eg, nets, machinery, footwear and clothing) thoroughly with an appropriate decontamination solution before putting it in any new water way.

DRY

If you can't clean your gear or animals, restrict use to a single waterway or dry completely to the touch inside and out, and then leave to dry for at least another 48 hours.

What else can I do to prevent aquatic weed invasions?

  • Do not throw any aquarium or pond material into waterways. Instead, put all unwanted pond material on the garden or compost - your small oxygen weed may become the next threat to native fish, birds and plants.
  • Do not give plants or plant parts away to others until you are sure they are not a threat to our waterways.
  • Make wise decisions on how to avoid increasing nutrient levels in waterways from fertiliser. High levels of nutrients running into waterways tend to encourage vigorous growth of some weeds.
Management strategy

Egeria is an unwanted organism which is listed on the National Pest Plant Accord. This means it is illegal to propagate, distribute or sell it within New Zealand.

If you think you have found Egeria in Canterbury, contact Environment Canterbury on 0800 EC INFO. Environment Canterbury will undertake control of this pest is found in Canterbury.

Entire marshwort (Nymphoides geminata)

Entire marshwort

Background
Entire marshwort is a floating-leaf aquatic pest plant with ‘lily’ shaped leaves and yellow flowers on long stalks. It is a perennial plant originating from Australia. It came to New Zealand through the ornamental pond plant trade. It prefers growing in slow-flowing freshwater less than one metre deep, and can survive in damp mud.
Description
  • Heart-shaped leaves float on the water surface like small water lily leaves.
  • Long stems (stolons) lie just below the water’s surface.
  • Leaves are bright green on the upper-side and can be pinkish in colour on the under-side.
  • It grows bright yellow flowers that have five petals with fringed edges.
  • Yellow-fringed edged flowers are held on stalks above the water surface.

Find out more about Entire marshwort:

Why is it a problem?

When entire marshwort is established, it forms dense mats of floating leaves. These dense mats out-compete both submerged and floating native aquatic species. Dense infestations de-oxygenate the water, causing harm to aquatic life.

Large masses of entire marshwort can choke and disrupt the recreational use of waterways. Entire marshwort spreads easily by broken fragments and creeping stem growth.

Control & management

You can prevent the spread of aquatic pests like entire marshwort by using the 'Check, Clean, Dry' method whenever you change waterways.

Environment Canterbury undertakes control of entire marshwort with the aim of elimination. Please report suspected sighting of entire marshwort to Environment Canterbury on 0800 EC INFO.

CHECK

Check boats, trailers and anything else that was in the water, including your dog’s paws if your dog is in the water with you, for any plant material and remove it. Even if the plant appears dry and dead, it may still survive and start a new infestation. Leave debris at the site or if you find any later, treat and dispose of it in the rubbish. Do not wash down drains.

CLEAN

Wash all equipment (eg, nets, machinery, footwear and clothing) thoroughly with an appropriate decontamination solution before putting it in any new water way.

DRY

If you can't clean your gear or animals, restrict use to a single waterway or dry completely to the touch inside and out, and then leave to dry for at least another 48 hours.

What else can I do to prevent aquatic weed invasions?

  • Do not throw any aquarium or pond material into waterways. Instead, put all unwanted pond material on the garden or compost - your small oxygen weed may become the next threat to native fish, birds and plants.
  • Do not give plants or plant parts away to others until you are sure that they are not a threat to our waterways.
  • Make wise decisions on how to avoid increasing nutrient levels in waterways from fertiliser. High levels of nutrients running into waterways tend to encourage vigorous growth of some weeds.
You can prevent the spread of aquatic pests like entire marshwort by using the 'Check Clean Dry' method whenever you change waterways.

Environment Canterbury undertakes control of entire marshwort with the aim of elimination. Please report suspected sighting of entire marshwort to Environment Canterbury on 0800 EC INFO.

Management strategy

Entire marshwort is an unwanted organism which is listed on the National Pest Plant Accord. This means it is illegal to propagate, distributed or sell it within New Zealand.

If you think you have found entire marshwort in Canterbury, contact Environment Canterbury on 0800 EC INFO. Environment Canterbury will undertake control of this pest if found in Canterbury.

Hornwort (Ceratophyllum demersum)

Hornwort

Background

Hornwort is a submerged free-floating perennial that grows in freshwater up to a depth of 16m. It originates from Asia, Africa, Australia, Malaysia and North America. It came into New Zealand through the aquarium and pond trade. It is likely to invade still or slow-moving water bodies and lagoons.

Description
  • Hornwort leaves are stiff and forked with teeth on the outer edge. They are densely crowded at the stem tip and become more spaced out the further down the stem.
  • No roots are present - usually lightly anchored by buried stems and leaves.
  • Green stems are 30-150cm long.
  • Stems are branched, still and brittle and resemble the shape of a pine tree.
  • Stems may float or be submerged.
  • Leaves attached to the stem are thin and dark green about 1-4cm long.
  • Leaves are in spirals of between 7-12 around the stem.
  • Produces minute green or white flowers, but is not known to fruit in New Zealand.

Find out more about Hornwort:

Why is it a problem?

Hornwort rapidly forms dense beds of plant matter, shading out and preventing native species from growing. It causes blockages in waterways and contributes to flooding. When it rots, it stagnates the water killing other freshwater species.

It threatens most submerged plant communities. It also negatively affects boating, fishing and other recreational activities once established.

Control & Management

CHECK

Check boats, trailers and anything else that was in the water, including your dog’s paws if your dog is in the water with you, for any plant material and remove it. Even if the plant appears dry and dead, it may still survive and start a new infestation. Leave debris at the site or if you find any later, treat and dispose of it in the rubbish. Do not wash down drains.

CLEAN

Wash all equipment (eg, nets, machinery, footwear and clothing) thoroughly with an appropriate decontamination solution before putting it in any new water way.

DRY

If you can't clean your gear or animals, restrict use to a single waterway or dry completely to the touch inside and out and then leave to dry for at least another 48 hours.

What else can I do to prevent aquatic weed invasions?

  • Do not throw any aquarium or pond material into waterways. Instead, put all unwanted pond material on the garden or compost - your small oxygen weed may become the next threat to native fish, birds and plants.
  • Do not give plants or plant parts away to others until you are sure that they are not a threat to our waterways.
  • Make wise decisions on how to avoid increasing nutrient levels in waterways from fertiliser. High levels of nutrients running into waterways tend to encourage vigorous growth of some weeds.
Management strategy

Hornwort is an unwanted organism which is listed on the National Pest Plant Accord. This means it is illegal to propagate, distribute or sell it within New Zealand.

If you think you have found Hornwort in Canterbury, contact Environment Canterbury on 0800 EC INFO. Environment Canterbury will undertake control of this pest is found in Canterbury.

Lagarosiphon (Lagosiphon major)

Lagorosiphon

Background

Lagarosiphon, commonly referred to as ‘oxygen weed’, is a freshwater pest plant.  It is scattered around the South Island of New Zealand.  It grows in lakes, drains, slow-moving rivers, garden ponds, and aquariums.

Lagarosiphon is present in a few waterways within Canterbury, including Lake Benmore and in private garden ponds and aquariums.

Description
  • Fast-growing, submerged, freshwater species.
  • Downward curling leaves are arranged spirally on the stem.
  • The leaves are 6-20 mm long and attached to very brittle stems.
  • Grows in sandy or silty substrates.

Find out more about Lagarosiphon:

Why is it a problem?

Lagarosiphon grows fast to form dense mats of vegetation, displacing native aquatic plants. It alters the nutrient status of lakes, blocks waterways and affects the recreational use of water bodies.  Humans are the main transporter of Lagarosiphon.

It spreads from one waterway to another when stem fragments attach to boats, trailers, fishing equipment and eel/fishnets. It is a problem in the Waitaki Lakes district costing hundreds of thousands of dollars to control so that recreational, environmental, and power generation is not more widely adversely affected.

Control & Management

CHECK

Check boats, trailers and anything else that was in the water, including your dog’s paws if your dog is in the water with you, for any plant material and remove it. Even if the plant appears dry and dead, it may still survive and start a new infestation. Leave debris at the site or if you find any later, treat and dispose of it in the rubbish. Do not wash down drains.

CLEAN

Wash all equipment (eg, nets, machinery, footwear and clothing) thoroughly with an appropriate decontamination solution before putting it in any new water way.

DRY

If you can't clean your gear or animals, restrict use to a single waterway or dry completely to the touch inside and out and then leave to dry for at least another 48 hours.

What else can I do to prevent aquatic weed invasions?

  • Do not throw any aquarium or pond material into waterways. Instead, put all unwanted pond material on the garden or compost - your small oxygen weed may become the next threat to native fish, birds and plants.
  • Do not give plants or plant parts away to others until you are sure that they are not a threat to our waterways.
  • Make wise decisions on how to avoid increasing nutrient levels in waterways from fertiliser. High levels of nutrients running into waterways tend to encourage vigorous growth of some weeds.
Management strategy

Lagarosiphon major is an unwanted organism which is listed on the National Pest Plant Accord. This means it is illegal to propagate, distribute or sell it within New Zealand.

Environment Canterbury aims to prevent the establishment of Lagarosiphon in those water bodies outlined in the below list, and contain it where it is present in any other water body.

Appendix 5 Lagarosiphon Schedule

The following schedule outlines the water bodies that will be protected from Lagarosiphon infestation:

  • Lake Ohau and the tributaries that flow into it;
  • Lake Pukaki and the tributaries that flow into it;
  • Lake Alexandrina and the tributaries that flow into it;
  • Lake Tekapo and the tributaries that flow into it;
  • Lake Heron and the tributaries that flow into it;
  • Lake Coleridge and the lakes and tributaries that flow into it;
  • Waimakariri River above the gorge at Woodstock, including the lakes and tributaries that flow into it above the gorge;
  • Ashley River above the Ashley Gorge Road bridge, including the lakes and tributaries that flow into it above that point;
  • Hurunui River above SH 7, including the lakes and tributaries that flow into it above that point;
  • Waiau River above the Waiau/Hanmer confluence, including the lakes and tributaries that flow into it above that point; and
  • Clarence River above the Clarence/Acheron confluence, including the lakes and tributaries that flow into it above that point.

Environment Canterbury conducts annual surveys of these waterways. We have signage in the Waitaki Lakes requesting freshwater users to check and clean their gear between waterways to prevent the spread of Lagarosiphon and other aquatic pests.  Our regional ‘Check Clean Dry’ campaign includes having a freshwater pest advocacy officer in the Waitaki Lakes over the peak Christmas/New Year period promoting the need and techniques to check, clean and dry gear to prevent aquatic pests from spreading.

Parrot's feather (Myriophyllum aquaticum)

Parrots feather

Background

Parrots feather is native to the Amazon River in South America. Overseas it grows in freshwater streams, ponds, lakes, rivers and canals that have a high nutrient content.  Because it is attractive and easy to propagate, it has spread worldwide for use in aquariums and ponds. The mats it produces provides a good breeding ground for mosquitos. We believe Canterbury is free from Parrot's feather.

Description
  • Freshwater weed.
  • Pale blue/green leaves are feather-like and have a rounded tip.
  • Leaves grow in groups of four to six around the stem.
  • Stems can grow up to 10 centimetres above the water surface.
  • Stems attach to the bottom of the waterbody and can grow up to two metres long.

Find out more about Parrot's feather:

Why is it a problem?

Parrot’s feather forms dense, surface-floating mats of vegetation, shading out and preventing native species from growing. It spreads easily by stem fragments.

If you think you have found Parrot’s feather in Canterbury, contact Environment Canterbury on 0800 EC INFO. Environment Canterbury will undertake control of this pest is found in Canterbury.

Control & Management

CHECK

Check boats, trailers and anything else that was in the water, including your dog’s paws if your dog is in the water with you, for any plant material and remove it. Even if the plant appears dry and dead, it may still survive and start a new infestation. Leave debris at the site or if you find any later, treat and dispose of it in the rubbish. Do not wash down drains.

CLEAN

Wash all equipment (eg, nets, machinery, footwear and clothing) thoroughly with an appropriate decontamination solution before putting it in any new water way.

DRY

If you can't clean your gear or animals, restrict use to a single waterway or dry completely to the touch inside and out and then leave to dry for at least another 48 hours.

What else can I do to prevent aquatic weed invasions?

  • Do not throw any aquarium or pond material into waterways. Instead, put all unwanted pond material on the garden or compost - your small oxygen weed may become the next threat to native fish, birds and plants.
  • Do not give plants or plant parts away to others until you are sure that they are not a threat to our waterways.
  • Make wise decisions on how to avoid increasing nutrient levels in waterways from fertiliser. High levels of nutrients running into waterways tend to encourage vigorous growth of some weeds.
Management strategy

Parrot’s feather is an unwanted organism as well as listed on the National Pest Plant Accord. This means it is illegal to propagate, distributed or sell it within New Zealand.

If you think you have found Parrot’s feather in Canterbury, contact Environment Canterbury on 0800 EC INFO. Environment Canterbury will undertake control of this pest is found in the region.

Phragmites (Phragmites australis)

Phragmites flowering

Background

Phragmites originates from the United States and Europe. The New Zealand nursery trade sold phragmites before it became an unwanted organism. Phragmites are present in New Zealand in variegated (green and white striped leaves) and non-variegated forms. There may be plants in older gardens due to the historic nursery trade.  Phragmites grow in fresh water and tolerate slightly saline conditions as well as growing away from water. Environment Canterbury undertakes control of all known phragmites sites.

Description
  • Perennial grass that grows between two and four metres tall and dies back over winter.
  • Leaf blades are flat, long and smooth, growing up to 60 centimetres long.
  • Leaf margins are rough and leaf sheaths overlap.
  • Stems are hollow.
  • Grows dense dark purple feathery flower heads 20 to 50 centimetres long.
  • Ligule (the membrane on the inside of the leaf, at the point where the blade leaves the stem) has a fringe of long hairs.

Find out more about Phragmites:

Why is it a problem?

Phragmites grows vigorously. In the right conditions, it will form dense stands, excluding native vegetation and modifying the habitat of animals that live in waterway margins. Broken rhizomes (underground horizontal stems) are the main method of spread.

Control & Management
  • CHECK

    Check boats, trailers and anything else that was in the water, including your dog’s paws if your dog is in the water with you, for any plant material and remove it. Even if the plant appears dry and dead, it may still survive and start a new infestation. Leave debris at the site or if you find any later, treat and dispose of it in the rubbish. Do not wash down drains.

    CLEAN

    Wash all equipment (eg, nets, machinery, footwear and clothing) thoroughly with an appropriate decontamination solution before putting it in any new water way.

    DRY

    If you can't clean your gear or animals, restrict use to a single waterway or dry completely to the touch inside and out and then leave to dry for at least another 48 hours.

    What else can I do to prevent aquatic weed invasions?

    • Do not throw any aquarium or pond material into waterways. Instead, put all unwanted pond material on the garden or compost - your small oxygen weed may become the next threat to native fish, birds and plants.
    • Do not give plants or plant parts away to others until you are sure that they are not a threat to our waterways.
    • Make wise decisions on how to avoid increasing nutrient levels in waterways from fertiliser. High levels of nutrients running into waterways tend to encourage vigorous growth of some weeds.
Management strategy

Phragmites is one of MPI’s top 11 plants to work toward eradicating from New Zealand. It is an unwanted organism under the Biosecurity Act 1993 and is included in the National Plant Pest Accord. It is illegal to knowingly release or spread, display or sell, breed, propagate or otherwise distribute this species. This pest is part of the National Interest Pest Response programme. Please report sightings to the Ministry of Primary Industry’s exotic pest and disease hotline on 0800 8099 66.

Yellow water lily (Nuphar lutea)

Yello water lilly

Background

Yellow water lily entered New Zealand from South America. Prior to confirming its presence in Canterbury around 2008, at Horseshoe Lake, it was only known to be in Central Hawke’s Bay*.

Once established, yellow water lily is difficult to control so which is why Horseshoe Lake is managed to reduce its population.

*Kerryn Pollock, 'Hawke’s Bay region - Plants and animals', Te Ara - the Encyclopedia of New Zealand.

Description
  • Grows in shallow freshwater and wetlands.
  • Big (30cm long) oval, leaves with a deep incision at one end giving a heart shape.
  • Stalked buttercup-like flowers six centimetre across that protrude above leaves.
  • Flowers have a strong alcoholic scent.
  • Two to three centimetres long, green, flask-shaped fruit, containing hundreds of long-lived seeds.
  • Stout spongy submerged tuber-like rhizome up to 10 centimetres thick.

Find out more about Yellow water lily:

Why is it a problem?

Yellow water lily is very adaptable and can survive droughts. It tends to grow in still or slow flowing water less than two metres deep. Water lily propagates from rhizomes and seeds. It spreads via seeds or stem fragments carried by water, boats, fishing gear or machinery. It rapidly invades shallow drains, ponds and lakes. Dense mats of leaves covering the surface of waterways can cause die-off of submerged native water plants, excessive water loss from ponds and oxygen deprivation. Mats of the plant reduce recreational values of waterways and impede water flow leading to siltation.

Control & Management
  • CHECK

    Check boats, trailers and anything else that was in the water, including your dog’s paws if your dog is in the water with you, for any plant material and remove it. Even if the plant appears dry and dead, it may still survive and start a new infestation. Leave debris at the site or if you find any later, treat and dispose of it in the rubbish. Do not wash down drains.

    CLEAN

    Wash all equipment (eg, nets, machinery, footwear and clothing) thoroughly with an appropriate decontamination solution before putting it in any new water way.

    DRY

    If you can't clean your gear or animals, restrict use to a single waterway or dry completely to the touch inside and out and then leave to dry for at least another 48 hours.

    What else can I do to prevent aquatic weed invasions?

    • Do not throw any aquarium or pond material into waterways. Instead, put all unwanted pond material on the garden or compost - your small oxygen weed may become the next threat to native fish, birds and plants.
    • Do not give plants or plant parts away to others until you are sure that they are not a threat to our waterways.
    • Make wise decisions on how to avoid increasing nutrient levels in waterways from fertiliser. High levels of nutrients running into waterways tend to encourage vigorous growth of some weeds.
Management strategy

Yellow water lily is an unwanted organism which is listed on the National Pest Plant Accord. This means it is illegal to propagate, distribute or sell it within New Zealand.

We are aware of a population in South Canterbury that we are working towards eliminating with annual control.

If you think you have found yellow water lily in Canterbury, contact Environment Canterbury on 0800 EC INFO. Environment Canterbury will undertake control of this pest is found in Canterbury.

*The South Island is a controlled area for didymo. This makes it a legal requirement to clean all gear and equipment that has been used in waterways before moving between Islands.

Note: It is an offence under Section 52 of the Biosecurity Act to knowingly transport a pest or unwanted organism to another waterway, and the penalty upon conviction for an individual person, is impisonment for up to five years and/or a fine of up to $100,000. So be sure to Check, Clean, Dry - everywhere, every time.