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Giant Reed

Also known as:
Bamboo Reed, Donax Cane, Arundo Grass, Cow Cane, River Cane, Reed Grass

General description

Sturdy, perennial, bamboo-like grass. Rhizomes are thick, lumpy and spread in continuous clumps < 1 m thick. Stems are spreading, clumping and < 6 m tall. Leaves are maize-like, sharp-edged, < 60 x 5 cm and opposite. Flowers are borne in large, fluffy, purplish turning to silver inflorescences.

What you need to know

To help protect our environment:

  • You must not breed, distribute, release or sell giant reed. As giant reed is a National Pest Plant Accord species, these restrictions apply within the Auckland region and across the whole of New Zealand.
  • You must not plant giant reed within the Auckland region.
  • You must destroy any giant reed on land that you occupy if it has been planted in breach of the above rules and you are directed to do so by an authorised person.
Auckland Council will control giant reed at all sites within the Aotea/Great Barrier Island group where it is known to occur.

If you see giant reed anywhere on Aotea/Great Barrier Island group, please report it to Auckland Council at

Auckland Council will manage giant reed in buffer areas of parks where giant reed is being managed. However, if you wish to help protect your local parkland, you are encouraged to control or remove any giant reed on your land and plant a better alternative instead.

View a map of park buffers.

To find out more about how we’re protecting Auckland’s parkland from pest plants, visit our pest plant buffer pages.

Riparian and forest margins, wetlands, saltmarshes, gullies, dunes, roadsides.

Seeds dispersed by wind. Vegetative spread from rhizomes, rhizome fragments and stem layering.

Forms dense stands and displaces native vegetation. Alters hydrology by blocking water flow. Impedes drainage and exacerbates flooding in agricultural systems.

Site Management

Follow up treated areas 3 times per year. Encourage natural regeneration of native plants or replant treated areas where possible after 2-3 treatments to establish dense ground cover and minimise reinvasion.

Recommended approaches

Do not attempt to undertake control of this species on Aotea/Great Barrier Island group. Please report to Auckland Council if seen on Aotea/Great Barrier Island group.

Physical control

Method: cut stems and dig out rhizomes

Plant parts requiring disposal: Rhizomes and roots

Disposal options: Stem cannot be chipped and used as mulch as it can regrow or remove to landfill


Check for presence of agents:
Giant reed gall wasp (Tetramesa romana)
Giant reed scale insect (Rhizaspidiotus donacis)

Community agrichemical control recommendations

No qualifications
For small infestations:
Cut stump and paste freshly cut base of stems with double strength glyphosate gel
Cut stump and spray freshly cut base of stems with 250ml glyphosate green per 1L of water
Cut stump and foliar spray regrowth with 150ml glyphosate green per 10L of water
Stems can be stacked in piles and foliar sprayed or removed to landfill

Basic Growsafe certified

Certified Handler/Experienced agrichemical user
For large infestations amongst desirable broadleaf species:
Cut stump and foliar spray regrowth with 150ml haloxyfop-P-methyl per 10L of water
For infestations amongst desirable species:
Cut stump and very carefully foliar spray regrowth with 150ml glyphosate green per 10L of water avoiding any spraying on desirable species foliage
Stems can be stacked in piles and foliar sprayed or removed to landfill

CAUTION: When using any herbicide or pesticide please read the label thoroughly to ensure that all instructions and safety requirements are followed.

Similar species

Phyllostachys species

Bamboo has much harder canes and smaller leaves.

Phragmites australis

Phragmites is shorter and the stems are narrower in proportion to the leaves.

RPMP status

Aotea (Eradication)
Parkland with Significant Ecological Areas (Site-led)
Whole region (Sustained Control)
National Pest Plant Accord Species
Giant reed - Main species image