Pampas
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Pampas: common and purple (and cultivars)
Cortaderia selloana and C.jubata Other common names: Cutty grass
Why it is a pest plant
| Production threat | Environmental threat | Public threat |
Pampas is a very invasive grass. Its leaves are razor-sharp hence its common name, ‘cutty grass’. It is a serious threat to some natural areas like sand dunes, stream banks and coastal cliffs where it can completely replace native vegetation. It is a particular problem on roadsides (reducing visibility), along railways, in quarries and in newly planted forests. Pampas can be a fire risk due to the large amount of dry matter it produces. It also harbours pests such as rats, mice, rabbits and possums.
There are two species of pampas in New Zealand – common pampas (Cortaderiaselloana) and purple pampas (C. jubata). Both species are native to South America. Infestations of both species are now found throughout the Waikato. Common and purple pampas are often confused with native toetoe (see identifying features for the differences).
Identifying features
Native toetoe
Flower
- Drooping flower heads are creamyyellow.
- Flowers October to January.
Fruit/seed
- No fruit but flowers produce large fluffy seed heads.
Leaf
- Tougher leaves and stems than pampas – livestock unlikely to eat it.
- White, waxy covering on leaf bases.
- Veins visible between the midrib and margin of leaves.
Purple pampas
Flower
- Flowering stems mostly purple, fading to dull brown.
- Flowers from February to April.
Fruit/seed
- No fruit but flowers produce large fluffy seed heads.
Leaf
- Leaf bases are not waxy.
- Dark green leaves, stout hollow stems.
- Easily torn leaves and stems make it an attractive food for livestock.
Common pampas
Flower
- Upright flowering stems are white, pink or purple.
- Flowers from February to April.
Fruit/seed
- No fruit but flowers produce large fluffy seed heads.
Leaf
- Upper side of leaf bluish-green.
- Leaves have serrated cutting edges.
- Leaf bases are not waxy.
- Easily torn leaves and stems make it an attractive food for livestock.
Differences between pampas and native toetoe – flowering characteristics
Native toetoe
Austroderia fulvida, A. richardii, A. toetoe, A. splendens
Flowering time: October to January
Flower heads: Generally drooping, usually light creamy-yellow.
Height when flowering: Up to 6m
Pampas
Common pampas including cultivars ‘gold stripe’ or ‘gold band’ Cortaderia selloana
Flowering time: February to April
Flower heads: Usually erect and dense. Colour variable – generally white, pinkish or purplish.
Flowers with fluffy hairs (female) or hairless.
Height when flowering: Up to 6m
Purple pampas C. jubata
Flowering time: February to April
Flower heads: Erect, dense and very uniform.
Flowering stems mostly purple, fading to dull brown.
Height when flowering: Up to 3m
Differences between pampas and native toetoe – leaf characteristics
Native toetoe
Austroderia fulvida, A. richardii, A. toetoe, A. splendens
LEAF BASE: Has white waxy surface.
Do not snap readily.
Midrib continues into leaf base.
Distinct secondary veins between midrib and leaf edge.
Dead leaves droop but do not form a spiral.
Pampas
Wood shaving-like dead leaves at base of pampas. Cortaderia selloana
Leaf base: Smooth or sparsely hairy. No waxy surface.
Leaf tips: Large numbers visible at all heights above ground level.
Leaf surface: Upper leaf surface bluish-green, lower surface dark green.
Snap readily when given a sharp tug.
Conspicuous midrib. Does not continue into leaf base.
No distinct secondary veins between midrib and leaf edge.
Dead leaf bases hang down and forms spirals. Plant builds up on a base of dead leaves, which resemble wood shavings.
C. jubata
Leaf base: Generally very hairy (the base flower stalk is too). No waxy surface.
Leaf tips: Mainly at ground level and much less visible.
Leaf surface: Both leaf surfaces usually dark green.
Snap readily when given a sharp tug.
Conspicuous midrib. Does not continue into leaf base.
No distinct secondary veins between midrib and leaf edge.
Dead leaf bases hang down and forms spirals. Plant builds up on a base of dead leaves, which resemble wood shavings.
Responsibility for control
All landowners/occupiers in some areas of the Waikato are responsible for the control of pampas on their property.
Landowners/occupiers in Taupō, South Waikato, Rotorua, Waitomo and Ōtorohanga districts are responsible for controlling pampas on their properties. Pampas is also banned from being sold, propagated, distributed or included in commercial displays.
A science study supported by Waikato Regional Council has shown that it is not feasible for the council to place control programmes in warmer coastal areas, where pampas is much harder to control. Other landowners/occupiers (additional to those in the areas listed above) are however encouraged to control and/or remove these plants from their properties where possible.
How to control pampas
Physical control
- Pampas can inflict nasty cuts, so wear gloves and protective clothing.
- For young plants, the best option is to loosen the soil and pull them out.
- For small infestations, cut the trunk or stems off as close to the ground as possible.
- A digger or bulldozer can be used to remove big plants.
- Physical control should be done before seeds form.
- Leaf matter can be left on site, acting as mulch and shading out the seed bank.
Herbicide control
Herbicides are most effective on pampas during spring and early summer while it is growing strongly. Spraying while the plants are flowering is less effective.
Cut stump treatment
- Plants can be slashed to about 30cm from the ground and the regrowth sprayed.
- Large mature clumps may require follow up control.
Spray application
- Very dense sites can be sprayed. Total coverage of the plant is required.
Safety when using herbicides
- Follow the instructions on the manufacturer’s label.
- Always wear protective clothing.
- Always minimise the risk to your other plants.
- Contact the supplier for further advice.
Summary of herbicides and application methods for control
Herbicide |
Application |
| Glyphosate and penetrant | Spray |
| Haloxyfop and crop oil | Spray |
| Herbicide rules will apply. You may need to notify neighbours if spraying. The Waikato Regional Plan explains the agrichemical (herbicides) use rule in section 6.2 | |
| If applying herbicide over water, a resource consent may be required. Please check with Waikato Regional Council before you begin. | |
Management
After initial control, it’s important to:
- clean out the site again at least annually to control regrowth
- stop weeds invading by replanting with non-pest plants (preferably native plants) once regrowth is no longer a problem.
More information
Advice
- For advice and additional information on control methods, call our pest plant staff on freephone 0800 BIOSEC (0800 246 732).
- Chemical company representatives, farm supply stores and garden centres can also be good sources for advice.
Publications
View, download or order the following publications or call our freephone 0800 800 401.
- National Pest Plant Accord (Manual of plants banned from sale, propagation and distribution) ($10.00 plus GST)
- Plant Me Instead! (Plants to use in place of common pest plants) (free)
- Waikato Regional Pest Management Plan (RPMP) (free) (Section 5.69, page 163)
- Waikato Regional Council pest guide (free)
Web
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