Management Information
Preventative measures: A Risk assessment of Cortaderia selloana for Australia was prepared by Pacific Island Ecosystems at Risk (PIER) using the Australian risk assessment system (Pheloung, 1995). The result is a score of 24 and a recommendation of: reject the plant for import (Australia) or species likely to be a pest (Pacific). Physical: Seedlings and small plants can be hand pulled or dug up especially in loose ashy soils. It is somewhat harder to pull or dig up in lava and compounded soils. Larger plants can be removed by heavy machinery. Care should be taken to contain any seeds or flowering stalks and these should be double bagged and disposed of in the garbage or left on site. Workers should take care to protect themselves when manually removing Cortaderia as it has sharp serrated leaves that can cut unprotected skin (Starr et al. 2003). Care should also be taken that all rhizomes are removed so there is no re-establishment.
Chemical: Chemical control is resorted to when mechanical removal cannot be employed. Foliar applications of Roundup (4% solution) or Roundup Pro (2% solution) (any glyphosate product) are effective in controlling pampas grass (Starr et al. 2003). Plants should be sprayed until wet but not to the point of run off. In wild areas, aerial spray by helicopter is employed. Leaving plants in place after spraying will result in less disturbance and may help reduce subsequent seedling germination in the area. May et al. (UNDATED) suggest removing the foliage first through cutting or burning, and then treating the re-growth with a post-emergence herbicide.
Location Specific Management InformationCuvier Is. (New Zealand)
Control was initated in 1998. New Zealand
Several control options are being used in New Zealand. Comprehensive information is available in the Department of Conservation Publication Review of control methods for pampas grasses in New Zealand .
Physical removal includes pulling out seedlings, hand grubbing, digging and the use of earth moving machinery (this can cause damage to surrounding vegetation). Hand removal is useful on sites where there is light infestations and where access is limited. This method can be labour intensive.
Grazing has been used in plantation forests and is found useful in early stages of infestations and has to include several grazings per year. The limitations are access to sites. Oversowing with pastrure species has also been used in cleared plantation areas or areas of site preparation.
Glysophate and monocot-specific herebicides have been found useful, where herbicide treatment is used. Velpar (hexazinone) granules have been used in plantation forests and isolated areas.
Aerial gun sparying and aerial spot spraying by helicopter have been used on difficult to reach sites. A Department of Conservation Publication Aerial spraying of pampas on difficult conservation sites. studies the relative efficiency of three devices used for spraying herbicides from a helicopter for the control of pampas on difficult to reach sites like coastal cliffs, swamps and dunes. Abseiling to reach sites with no access, has also been employed.
Feasibility studies of the biocontrol prospects of pampas are ongoing. Poor Knights Islands (New Zealand)
Control of Cortaderia spp. began in 1991, focussing on three obvious infestations on the coastline. It involved one trip per year by volunteers. In 1996, a Weed Eradication Strategy was developed. The islands were split into three management zones: weed sites, weed free sites prone to invasion, and weed free sites not prone to invasion. Existing weed sites occurred in areas of disturbance associated with exposed coastal faces, shrubland and broadleaf forest. An aerial search was conducted in early summer, and sweep searches were conducted over the weed sites during spring, when flowering is commencing. Any plants found were removed from the island. There has been a dramatic decline in numbers. A four year seedling absence will be required before sites can be declared weed-free. Reinvasion remains a threat, both by wind dispersal, and by the spread of seeds by management staff.
Both species of Cortaderia have been removed from the Poor Knights but eradication has never been achieved. A zero density adult population is being sustained . All plants were thought to have been removed in 2001/02 but further plants have since been found, some of which had set seed. Reinvasion from the mainland is suspected to be occurring. Sporadically over the last 4years individual plants have continued to appear in areas of the islands where there have not been adult pampas grass recorded. Plants have also occurred in old weed sites as recently as last year - potentially either old seed in the soil or seed rain shadow as well (Glen Coulston., pers.comm., February 2006). Rangitoto Is. (New Zealand)
In 1995, a weed control programme was initiated on Rangitoto Island, with 72 weed species identified. These were split into three priority classes, each with a management objective. The long term aim for this species is sustained control. Raoul Is. (New Zealand)
Pampas plants growing on the retaining wall were pulled out, and adults found growing in subsequent years were also removed. Raoul Is. (New Zealand)
This species is subject to an eradication programme on Raoul Island, and is ranked Category A(i) - known to have the potential to significantly alter the vegetation of Raoul Island. Eradication commenced in 1984. Raoul Island has been divided into 13 weeding blocks for the purpose of controlling and eradicating alien plants since 1972, which make up 64% of the vascular plant flora on Raoul Island. These are divided into active plots which are searched at least twice a year, and null plots which are searched at least once every two years. Grid searching is used to examine the areas with easier access, while steep cliffs are searched using binoculars or a telescope. This is carried out when plants such as Caesalpinia decapetala are in flower (June-November). Aerial surveillance is carried out periodically which has been useful in identifying flowering trees such as Senna septemtrionalis, mature vines of Passiflora edulis or trees of Olea europaea ssp. cuspidata. The initial knockdown phase involved for most species the cutting of mature individuals and painting of stumps with herbicides, or scattering herbicide granules around them. Blanket spraying was used to treat dense, inaccessible infestations. Subsequent searches involve the removal of any seedlings or young plants found. If a mature plant is found, the fruit is removed for burning, the stem is cut and herbicide applied. Information regarding the eradication programme is stored on an Access database. The importation of alien plants to Raoul Island is prohibited. Taranaki Region (New Zealand)
C. jubata is classified as a 'Containment pest plant' in the The Pest Management Strategy for Taranaki. 'Containment pest plants' are pest plants that are abundant in suitable habitats in a region or part of a region and for which the long-term goal is to prevent the spread of the plant to new areas or to neighbouring properties.
Each pest plant has a management programme according to its designation. These programmes are summarised in the series of bulletins 'Pest Plant Facts'. Please see purple pampas: C. jubata for pest plant facts and management programmes.
Management Resources/Links
1. AME, 2004 Agence Méditerranéenne de l'Environnement. Plantes Envahissantes de la Region Mediterraneenne. Cortaderia selloana
Summary: In French- document on invasive C. selloana in the Mediterranean french area. Includes information on common names, images, ecology, background of the species in Europe, European distribution, distribution in France with a distribution map, control options, impacts and suggestions for alternative species.
Available from: http://www.ame-lr.org/plantesenvahissantes/index.html [Accessed October 1 2004] 7. Lambrinos, J. G. 2001. The expansion history of a sexual and asexual species of Cortaderia in California, USA. Journal of Ecology 89: 88-89.
Summary: A historical research paper that tracks the evolution and expanding distribution of species. Also provides some management suggestions and distribution information. 8. May, Michael, Cristina Grosso, and Josh Collins., 2003. Pampas grass. Practical Guidebook for the Identification and Control of Invasive Aquatic and Wetland Plants in the San Francisco Bay-Delta Region San Francisco Estuary Institute Oakland, California
Summary: Information on description, economic importance, distribution, habitat, history, growth, and impacts and management of species.
Available from: http://www.sfei.org/nis/pampasgrass.html [Accessed 22 June 2005].
The Guidebook is available from: http://www.sfei.org/nis/ 9. National Pest Plant Accord, 2001. Biosecurity New Zealand.
Summary: The National Pest Plant Accord is a cooperative agreement between regional councils and government departments with biosecurity responsibilities. Under the accord, regional councils will undertake surveillance to prevent the commercial sale and/or distribution of an agreed list of pest plants.
Available from: http://www.biosecurity.govt.nz/pests-diseases/plants/accord.htm [Accessed 11 August 2005] 10. New Zealand Plant Conservation Network, 2005. Unwanted Organisms. Factsheet Cortaderia selloana
Summary: The New Zealand Plant Conservation Network (NZPCN) provides information about New Zealand's most weedy exotic plant species and how to identify them. They also provide an on-line form to record observations of weed occurrences.
This page available from: http://www.nzpcn.org.nz/exotic_plant_life_and_weeds/index02.asp?Filter=c&FilterStatus=1
Lists of Exotic Plant life and Weeds available from: http://www.nzpcn.org.nz/exotic_plant_life_and_weeds/advanced_search.asp [Accessed 19 May 2005] 12. Plants For A Future, 2000. Cortaderia selloana
Summary: A searchable database and resource and information centre for edible and other useful plants.
Available from: http://www.ibiblio.org/pfaf/cgi-bin/arr_html?Cortaderia+selloana [Accessed 02 December 2003]. 14. Starr, F., K. Starr, & L. Loope. 2003. Cortaderia spp.. United States Geological Survey: Biological Resources Division, Haleakala Field Station, Maui, Hawai'i.
Summary: Information on description, economic importance, distribution, habitat, history, growth, and impacts and management of species.
Available from: http://www.hear.org/pier/pdf/pohreports/cortaderia_spp.pdf [Accessed 02 December 2003]. Results Page: 1
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