Pampas grass (Cortaderia species)

Profile

Impact

Pampas grass has become a major threat to national parks in and around Sydney and the Central Coast. Once established, the plant is very competitive, restricting the establishment of native trees, and can become a fire hazard and harbour vermin. Because of this, the Department of Environment and Climate Change has undertaken appropriate control programs in NSW.

Pampas grass is of greatest potential weed significance to forestry operations. However, it has not yet become a major problem in NSW forests.

Pampas grass is not considered an agricultural weed, because young plants are readily grazed by stock and it shows no ability to establish in cropping systems.

Distribution

In NSW pampas grass has mainly become naturalised in bushland on the Central Coast and in some areas of the Central Tablelands. In Sydney, it is considered a major environmental weed by many local councils and is subject to intensive control campaigns. Evidence suggests it is spreading quickly across land disturbed by coal mining to the west of Newcastle, with numerous small populations on the coastal plains of the north coast of NSW.

Distribution map

Spread

Individual plants have the ability to produce vast quantities of windborne seed – up to 100,000 per flower head – which can infest areas within a 25 km radius. In many cases, garden plants are the seed source for infestations. Pampas grasses also have the ability to reproduce from rhizomes (underground stems).

Cortaderia selloana (common pampas grass), the most common species in NSW, is gynodioecious. That means there are separate female and hermaphrodite or bisexual plants. Both types vary slightly in their appearance. The female plants are prolific seeders if pollinated by a hermaphrodite plant.

It is commonly thought that many of the cultivated plants in Australia are female clones, and fail to produce seed because of the lack of hermaphrodite plants to pollinate them. This could be why pampas grass has failed to naturalise in many parts of Australia where only individual plants are cultivated.

Cortaderia jubata (pink pampas grass) plants are always female and apomictic. That is, they can reproduce without the need for fertilisation. It is important that this be taken into account if control programs are to be effective.

Established plants have a large root system up to 3.5m deep, and the tussock produces large quantities of flammable material. It is very competitive with other more desirable plants. It is the more aggressive species in NSW.

Description

Pampas grass is a robust, long-lived perennial plant. It generally takes the form of a large tussock, approximately 1–1.5 m across, with attractive, plumed flower heads carried on tall stems.

Table 1: Comparison of Cortaderia species.
 Common pampas
Cortaderia selloana
Pink pampas
Cortaderia jubata
*New Zealand pampas
Cortaderia richardii
Flower heads appear Mid-March to late May January to late March October to January
Flower head colour Generally white but can be pink or mauve Always pink when young, fading to dark brown Straw to gold
Height of tussock 2 metres 1.5–2 metres 2-3 metres
Height when in flower Up to 6 metres Up to 4 metres, held high above arching leaves Up to 5 metres
Leaves
  • Erect and arching towards tip
  • Margins finely serrated
  • Arching with leaf tips touching the ground
  • Margins finely serrated
  • Arching with tips touching the ground
  • Margins finely serrated
Leaf sheath
  • No distinctive midrib
  • Smooth to sparsely hairy
  • No distinctive midrib
  • Very hairy
  • Distinctive midrib
  • Covered with white-waxy bloom
* Cortaderia richardii is currently not present in NSW; however, early identification is critical for effective control.

Habitat

Pampas grass appears to have no particular habitat preference, and is found in a wide range of ecosystems. It prefers open, sunny conditions, but also does particularly well in wetter conditions, making mangrove areas along rivers and inlets and wet, disturbed heathlands especially vulnerable to infestation.

Common sites of infestation are roadsides, road cuttings, quarry faces, sand dunes, mine spoil, new forest plantations and burnt and mechanically disturbed bushland. It can thrive in low-fertility situations and also tolerate waterlogged conditions.

References

Dellow J and McCaffery A (2009). Pampass grass Primefact 697. NSW DPI, Orange. 

References

  • Dellow, J. and McCaffery, A. (2003) Pampas Grass. Agfact P7.6.40. NSW DPI, Orange.
  • Parsons, W.T. and Cuthbertson, E.G. (1992) Noxious Weeds of Australia, 2nd ed. CSIRO publishing.

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Control

The method of control for pampas grass depends on the site on which it occurs and the potential risk for causing new infestations. Permanent mechanical removal is recommended wherever possible.Mechanical removal of plants (permanent removal, used in high-risk areas)

Grubbing of plants, particularly when small, is the best method of control in urban and bushland areas. This can be difficult with large plants because of their extensive root system and the abrasive nature of the leaves.

Control of large plants is easier and more effective if any seed heads are removed first and the plant is slashed before grubbing the crown and roots. Seed heads should be placed in a plastic bag and destroyed in an appropriate way.

The best conditions for grubbing are when the soil is moist so removal is easier. The crown and roots must be completely removed from contact with the soil. Suitable disposal methods for plant material are necessary to prevent re-establishment.

Pampas grass is known to be an important summer egg-laying site for wildlife such as the diamond python. Timing of control methods such as slashing should be considered to avoid the destruction of important habitats at critical times.

Use of herbicides (low-risk areas)

Smaller plants (less than 40cm) can be controlled using a wiper applicator with the recommended herbicide. For larger plants, slash the plant to reduce the foliage, taking care to dispose of any plant material in the appropriate way to prevent re-establishment, and then spray with the recommended herbicide.

Alternatively, the plant can be burnt (if local conditions allow), allowed to recover, and any new growth sprayed with the recommended herbicide.

Do not spray plants stressed by drought or frost, and ensure there is thorough wetting of larger plants with the herbicide. Follow-up treatment may be required if regrowth occurs. Prevention of seeding (temporary, used in low-risk areas).

Pampas grass is a prolific seeder. Its potential spread can be prevented by removing the flowering plumes before the pollen and seeds develop and are dispersed by the wind.

If removal is left until after the seed has developed, the seed head should be handled with care to prevent the seed shaking out. Any seed head containing viable seed should be burnt or rendered non-viable before discarding.

Grazing (temporary, used in low-risk areas)

Pampas grass is readily grazed by stock when it is young, before it becomes too abrasive. This prevents the development of flowers and seed set.

Herbicide options

WARNING - ALWAYS READ THE LABEL
Users of agricultural or veterinary chemical products must always read the label and any permit, before using the product, and strictly comply with the directions on the label and the conditions of any permit. Users are not absolved from compliance with the directions on the label or the conditions of the permit by reason of any statement made or not made in this information. To view permits or product labels go to the Australian Pesticides and Veterinary Medicines Authority website www.apvma.gov.au

See Using herbicides for more information.


Glyphosate 360 g/L (Roundup®)
Rate: 1.0 or 1.3 L per 100 L of water
Comments: Actively growing plants, before flowering, spring to autumn. Use higher rate on plants over 1 m high.
Withholding period: Nil.
Herbicide group: M, Inhibitors of EPSP synthase
Resistance risk: Moderate


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Legal requirements

The content provided here is for information purposes only and is taken from the Noxious Weeds Act 1993.

All species in the Cortaderia genus are declared.

Area Class Legal requirements
Albury 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Bayside 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Bega Valley 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Bellingen 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread and the plant must not be sold, propagated or knowingly distributed
Blue Mountains 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Burwood 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Cabonne 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Camden 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Campbelltown 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Canada Bay 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Canterbury-Bankstown 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Castlereagh Macquarie County Council 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Central Coast 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Cessnock 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Clarence Valley 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread and the plant must not be sold, propagated or knowingly distributed
Coffs Harbour 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread and the plant must not be sold, propagated or knowingly distributed
Cootamundra-Gundagai 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Cowra 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Cumblerland 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Dungog 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Eurobodalla 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Fairfield 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Federation 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed only in the area formerly known as Corowa Shire Council
Georges River 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Glen Innes Severn 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread and the plant must not be sold, propagated or knowingly distributed
Goulburn Mulwaree 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Greater Hume 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Gunnedah 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread and the plant must not be sold, propagated or knowingly distributed
Gwydir 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread and the plant must not be sold, propagated or knowingly distributed
Hawkesbury River County Council 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Hornsby 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Hunters Hill 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Illawarra District Weeds Authority 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Inner West 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Inverell 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread and the plant must not be sold, propagated or knowingly distributed
Ku-ring-gai 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Lake Macquarie 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Lane Cove 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Liverpool 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Liverpool Plains 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread and the plant must not be sold, propagated or knowingly distributed
Lord Howe Island 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Maitland 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Mid-Coast 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread and the plant must not be sold, propagated or knowingly distributed only in the area formerly known as Great Lakes Council
Mid-Coast 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed only in the areas formerly known as Gloucester Shire Council and Greater Taree City Council
Mid-Western Regional 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Moree Plains 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread and the plant must not be sold, propagated or knowingly distributed
Mosman 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Nambucca 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread and the plant must not be sold, propagated or knowingly distributed
Narrabri 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread and the plant must not be sold, propagated or knowingly distributed
Narromine 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
New England Tablelands County Council 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread and the plant must not be sold, propagated or knowingly distributed
Newcastle 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
North Sydney 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Northern Beaches 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Orange 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Parramatta 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Port Macquarie-Hastings 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Port Stephens 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Queanbeyan-Palerang Regional 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Randwick 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Rous County Council 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread and the plant must not be sold, propagated or knowingly distributed
Ryde 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Shoalhaven 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Snowy Monaro Regional 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread and the plant must not be sold, propagated or knowingly distributed
Snowy Valleys 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Southern Slopes County Council 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Strathfield 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Sutherland 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Sydney 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Tamworth Regional 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread and the plant must not be sold, propagated or knowingly distributed
Tenterfield 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread and the plant must not be sold, propagated or knowingly distributed
Upper Hunter County Council 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Upper Lachlan 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Upper Macquarie County Council 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread and the plant must not be sold, propagated or knowingly distributed
Waverley 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Western Plains Regional 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Willoughby 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Wingecarribee 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Wollondilly 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Woollahra 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed

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For technical advice and assistance with identification please contact your local council weeds officer.
For further information call the NSW Invasive Plants and Animals Enquiry Line on 1800 680 244 or send an email to weeds@dpi.nsw.gov.au

Reviewed 2016