ACT State of the Environment 2007

Indicator: Pest plants


A wide range of pest plants is established in the ACT and some have harmful impacts on native vegetation and biodiversity, rural enterprises, and health and public amenity. Following the 2003 bushfire, a substantial diversion of resources was required to control weeds in burnt pine plantations in the Lower Cotter catchment and other fire affected lands managed by Parks, Conservation and Lands, Department of Territory and Municipal Services (TAMS).

An important initiative in the reporting period was introduction of the Pest Plants and Animals Act 2005. The Act strengthens the legislative framework for dealing with pest plants, by setting out requirements for control of listed species and prohibiting supply of a large proportion of them, meaning they can no longer be sold by nurseries. Weed control has been coordinated through the ACT Weeds Strategy 1996–2006 and a revised strategy has been prepared to cover the next 10 years (2007–17). Under this strategy, a weeds working group will focus on weed control operations while an advisory group will provide strategic direction and expert advice.

While new legislation has been enacted and a revised pest plant management strategy has been prepared and are both welcome, there is little evidence that control programs are being evaluated for their effectiveness or if alternative programs have been considered let alone trialled. Over the next reporting period (2007–11) this deficiency will need to be addressed by all agencies and landholders alike and the next state of the environment report will include evidence of effective programs that have focused on achieving pest plant control, biodiversity conservation, and catchment management objectives.

In the reporting period invasive exotic grasses, woody weeds, willows and blackberry have continued to require extensive control. Biological control agents, for example, crown weevil (Mogulones lavratus), root weevil (Mogulones geographicus), pollen beetle (Meligethes planiusculus) and flea beetle (Longitarsus echii), have provided some assistance in the case of Paterson's Curse. Rangers also released a rust strain on blackberry, and a stem bore and seedeater for Scotch thistle.

What the results tell us about the ACT

Control of pest plants continues to be a major task for land managers in the ACT. Once pest plants are established, eradication is rarely possible, but may be achieved locally. Pest plant management requires ongoing funding commitment and programs must be adapted to changing circumstances. Examples of the latter in the reporting period included the need to respond to weed growth after the 2003 bushfire and the recognition that the rapidly evolving biology of willows needs to be kept under review. Expenditure on weed control by ACT Government land management agencies and community groups is currently between $1.5 and $2 million per annum. This does not include expenditure by Australian Government agencies and rural lessees. The total expenditure is, therefore, estimated to be more than $2 million per annum.

A large number of weed species are found in the ACT and they vary in their impacts. Some have low abundance and are minor weeds in native vegetation communities; others have spread dramatically in a short time to become widespread and abundant, for example, Chilean Needlegrass (Nassella neesiana) is difficult to recognise among other grasses and its spread is promoted by fire and mowing/slashing.

Significant groups of pest plants in the ACT are:

  • exotic grasses, such as Serrated Tussock (Nassella trichotoma), African Lovegrass (Eragrostis curvula) and Chilean Needlegrass (Nassella neesiana), which threaten remnant lowland native grasslands and woodlands
  • Willows (Salix spp.), whose rapid spread, environmental, economic and social impacts, and evolving biology are cause for major concern
  • Blackberry (Rubus fruticosus agg.), which is particularly prevalent in riparian and former pine plantation areas
  • woody weeds, such as Pyracantha, Broom and Cotoneaster, many of which derive from plants formerly used in gardens and for landscaping
  • St John's Wort (Hypericum perforatum), which is widespread but particularly a problem in remnant woodland reserves formerly grazed by sheep.

The new legislation (Pest Plants and Animals Act 2005) strengthens the legislative support for the ACT Government to deal with pest plants including prohibiting the sale of declared pest plant species.

Why there is concern about weeds

Weeds successfully spread to new areas and become established because of an ability to respond to changes in the landscape more quickly than other species. Weeds share some common characteristics. Typically they:

  • produce a lot of seed, in some instances they are able to spread by vegetative reproduction (e.g. broken branches from willows) and they out-compete native species
  • rapidly invade disturbed sites, tolerate a wide range of conditions and are less affected by pests and diseases.
  • negatively impact biodiversity by displacing native species, reducing habitat, and affecting fire regimes
  • negatively impact the economy through loss of rural production and cost of control, higher maintenance costs of parkland
  • adversely affect health and public amenity, for example, some weeds can affect human and animal health and others are a hazard to water sports and in recreation areas.
  • Weed invasion is a major threat to endangered ecological communities such as natural temperate grassland and lowland woodland and also to riparian vegetation (ACT Government 2004, 2005, 2007). It has been estimated that the cost of weeds to Australian agriculture exceeds $4 billion per annum (Australian State of the Environment Committee 2006).

ACT Weeds Strategy

Invasion and spread of pest plant species is relentless and control requires a coordinated, long-term response from land managers. The first ACT Weeds Strategy 1996–2006 (ACT Department of Urban Services 1996) provided a framework for programs to reduce the social, economic and environmental impacts of weeds in the ACT. Important initiatives since 1996 include:

  • establishment of the ACT Weeds Working Group
  • introduction of the Pest Plants and Animals Act 2005
  • preparation of pest plant management plans for the majority of species on the declared pest plant list
  • survey and mapping of weed distribution
  • coordinated weed control programs.

Public education, advice to nurseries and activities such as Weed Buster Week and the Weed Swap program are aimed at raising awareness about weed species and their control, especially in suburban gardens.

A revised weeds strategy has been prepared to cover the next 10 years (2007–17) (TAMS 2007). The strategy builds upon the experience of the last 10 years and takes account of changes such as the new legislation and declared pest plants list. The strategy provides for establishment of an ACT Land Managers Weeds Working Group that is focused primarily on coordination and implementation of weed control programs. As well, an ACT Weeds Advisory Group will provide the Working Group with strategic direction and expert advice, and will oversee and report on implementation of the weeds strategy. Both groups are established through the ACT Department of Territory and Municipal Services.

Weed management is essential for sustainable management of natural resources and the environment. The strategy for 2007–17 encourages prevention and early intervention as the most cost-effective approaches that can be deployed against weeds and contains objectives and strategic actions for protecting and enhancing biodiversity.

Determination of priority weed control programs is the foundation of the revised strategy, recognising the impossibility of effectively dealing with all weeds in all locations at the one time. Determining priority control programs will ensure strategic and focused allocation of available resources. The criteria for determining these priorities will vary with the assets or values that are being impacted, their sensitivity to impact, the characteristics of the weed involved and the level of control being sought. A holistic approach is often necessary to achieve optimal outcomes. This may include determining whether to apply resources in areas that have low infestation of weeds with a high capacity to invade or in high value areas that are infested with less aggressive weeds. Setting priorities for weed management in the ACT will include consideration of the impacts of weeds species on biodiversity values, thus determining how the available resources should be distributed among high- and low-value areas. By identifying the priority values to be protected, a more effective result can be achieved in a more efficient way.

The revised weeds strategy proposes the appointment of a specialist weeds ecologist, who will implement, monitor and evaluate the weed control program. This will show where weed control is working and where there is need to change direction in order to better protect biodiversity assets.

Regional and national context

The ACT Weeds Strategy is designed to complement the Australian Weeds Strategy (NRMMC 2006) and recognises the importance of giving a high priority to controlling weeds of national significance.1

Weeds of national significance species that are established in the ACT are:

  • Blackberry (Rubus fruticosus agg.)
  • Chilean Needle Grass (Nassella neesiana)
  • Gorse (Ulex europaeus)
  • Serrated Tussock (Nassella trichotoma)
  • Willow (Salix spp.)
  • Alligator Weed (Alternanthera philoxeroides)
  • Weeds of national significance species with the potential to establish in the ACT are:
  • Bridal Creeper (Asparagus asparagoides)
  • Cabomba (Cabomba caroliniana)
  • Salvinia (Salvinia molesta)

All species are declared pest plants in the ACT.


Introduction of the Pest Plants and Animals Act 2005 has improved the Territory's ability to protect land and aquatic resources from threats posed by pest plants. ACT declared pest plants are listed in the Pest Plants and Animals (Pest Plants) Declaration 2005 (No 1). Under the Act, some listed species are declared as notifiable or prohibited (propagation and supply prohibited). A pest plant declaration may state that the plant must be suppressed or contained. These provisions are based on the potential threat the species poses and the practicality of control measures. Suppression or destruction of a pest plant may be needed if that is achievable with current knowledge, techniques and resources. Containment may be a requirement if complete suppression or destruction is impractical. The Act provides for preparation of a pest plant management plan for a declared pest species. Such a plan is a statutory document (being a notifiable instrument under the Legislation Act 2001).

Control of pest plants is included in 'Land Action Plans' that form part of Land Management Agreements between lessees and the ACT Government. These agreements are required under Part 186C of the Land (Planning and Environment) Act 1991 for all non-urban leases in the ACT. However, due to the prolonged drought it has been impractical for rural lessees to undertake much of the intended weed control programs. Land Management Agreements have, however, been useful tools in being able to communicate with rural lessees about weed issues, particularly in areas with conservation values on the lease. This has enabled lessees, when weather conditions were suitable, to undertake coordinated control of high priority weeds on a sub catchment basis (for example, control of serrated tussock in the Lanyon Bowl/Paddys River subcatchments).

Cost of weed control

During the reporting period the total costs of weed control to ACT Government agencies and community groups was $7.345 million (see Table 1); this does not include expenditure by the Australian Government or rural landholders. The latter may have accessed ACT Land Keepers funding for weed control during the reporting period. ACT Land Keepers, a component of the Living Environment Program (funded by the Natural Heritage Trust), has been established to address biodiversity and riparian conservation measures on rural and non-urban land in the ACT.

Table 1: Cost of weed control by ACT Government agencies and community groups 2003–04 to 2006–07
2003–04 2004–05 2005–06 2006–07
Expenditure ($m) $1.428 $2.47* $1.777 $1.676

Note: * Includes site preparation for forestry plantations

The cost of weed control in high conservation areas includes undertaking weed control on land adjacent to reserves to prevent further weed incursions. The cost to ACT Government agencies of controlling weeds to protect conservation values in the Territory during 2007–08 amounted to $2,146,500 (see Table 2).

Table 2: Cost of weed control by ACT Government agencies during 2007–08 to protect conservation values
Reserves Adjoining land Urban roadsides Rural roadsides
Expenditure $605,000 $36,500 $100,000 $140,500

Potential new invasive species

The prolonged dry periods that many parts of Australia experienced during the reporting period have the potential to increase introduction of weeds through importation of feed for livestock. This situation may also result in introduction or colonisation of weed species from hotter drier climatic regions in Australia. The prolonged dry periods have created the potential for areas of heavily grazed agricultural land, nature reserves, urban parkland, open space areas, suburban and rural road verges and other areas of public land to become infested with pioneer type weed species, such as Capeweed (Arctotheca calendula), Paterson's Curse (Echium plantagineum) and Gazania. However, these species continue to be a low priority for treatment except those that have the potential to invade horse agistment enterprises. The potential for aquatic species to spread may also increase as recreational boat users travel to waterways they have not traditionally used.

The need for vigilant identification of new weed invasions relies on the TAMS retaining experienced field staff. This was evident when an experienced park ranged discovered a small patch of the invasive weed, Mexican feather grass (Nassella tenuissima) in the Territory. New weed invasions are expected to become more frequent as the climate changes.

Working with the community

The community groups, Parkcare and Landcare, help Parks, Conservation and Lands staff control weeds. In 2006–07 the dollar value of their voluntary time was between 5% and 10% of total expenditure on weed control. Their efforts in raising nature conservation awareness and, in a number of cases, professional expertise, make a valuable contribution to the overall weed control effort. For example, the work the Red Hill Parkcare Group undertakes on conserving the nationally endangered daisy, the Button Wrinklewort (Rutidosis leptorhynchoides).

Programs such as Weed Swap, coordinated by the Australian Native Plant Society, play an important role in raising awareness about woody weeds, in the general community. Conservation Volunteers Australia also plays an important role in raising awareness in the community, particularly on weekends when volunteers are largely local people. Additional benefits are realised through the awareness-raising activities of catchment groups.

Updated information for reporting period 2003–07 on priority pest plants listed in the Pest Plants and Animals (Pest Animals) Declaration 2005

TAMS has advised that reporting on progress with control of priority weeds will be part of the duties of the new position of the Weeds Ecologist. It is proposed that this position will undertake quantitative monitoring and evaluation of weed control efforts. This will allow an evaluation of whether the cover/abundance of a weed species is being reduced, contained or getting worse.

These species are all included in the Pest Plants and Animals (Pest Plants) Declaration 2005 (status indicated in brackets after species below). The weed control program is based on priority species and priority areas, developed in consultation with the ACT Weeds Advisory Group. This information is disseminated to all ACT land managers.

1. Alligator Weed (Alternanthera philoxeroides) (notifiable/prohibited)
Condition There is a continuing program to eradicate Alligator Weed from the ACT.
Impacts If not controlled, the weed can completely cover the surface of water bodies and wetlands, affecting native flora and fauna and agriculture. If not contained, the ACT infestation, although minor, could spread to the Murrumbidgee River and the Murrumbidgee Irrigation Area.
Response Education and awareness programs have been undertaken throughout the community. Control programs have been undertaken in residential areas to minimise the potential for spread to large urban water bodies.
As part of the Australian Government's Defeating the Weeds Menace Program, the ACT received funding of $61,000 to contain and eradicate alligator weed in the Murray Darling Basin during 2007–08. The New South Wales Department of Primary Industries managed the project on behalf of the ACT. Activities the grant funded included design and printing of brochures (Alligator weed – not a vegetable) that were also translated in Sinhalese (a Sri Lankan language), a television advertisement (aired on WIN TV from 23 December 2007 to 23 March 2008), and three public information workshops.
An additional $5000 is allocated to surveying and mapping alligator weed in urban water bodies in Gungahlin, Halls Creek and Tuggeranong. Any known infestations are treated biannually at a cost of approximately $4000 per year.
As part of Parks, Conservation and Lands' general weed awareness-raising program, displays, including live material where appropriate, have been set up at events such as Floriade and the Canberra National Agricultural Society Show, as well as all operational depots around the Territory.
Status and outlook Ongoing monitoring, eradication, containment and education are necessary and will be continued.
Preliminary evidence suggests that Alligator Weed has spread in Yerrabi Pond at Gungahlin and control of this pest plant will need to be conducted more frequently in the future.
Backyards are thought to be the only source of Alligator Weed infestations. It is crucial that these sources be identified. In the past, identification of backyard sources has relied on residents contacting Parks, Conservation and Lands after community awareness campaigns. However, this is relatively ineffectual, partially because it is difficult for the public to identify the species. Substantial resources need to be committed to trained staff conducting more thorough inspections of ACT backyards to determine the true extent of infestations.

2. Serrated Tussock (Nassella trichotoma) (must be contained/prohibited)
Condition Serrated Tussock is widespread throughout the ACT and has been identified as the highest priority species for control in all areas of the ACT, except species identified as notifiable under the Pest Plants and Animals Act 2005. Major infestations are concentrated in the Gungahlin, Jerrabomberra, Symonston, Fyshwick, Kowen, Kaleen, Lawson, North Lyneham, Gibraltar, Naas and Woodstock areas.
Impacts This is a highly invasive species with broad site tolerance. High conservation value Natural Temperate Grassland (Gungahlin, Jerrabomberra, Symonston) and Yellow Box-Red Gum Grassy Woodland is vulnerable to ongoing invasion.
Response High priority control programs have been implemented in all areas listed above.
Status and outlook Infestations in all areas have the potential to spread and significantly affect grazing and nature conservation land. Control of infestations in the Gungahlin area is compromised by the short-term tenure of rural leases and the ongoing withdrawal of greenfields sites for residential development.
The continuing drought has hampered the serrated tussock control program. The dry conditions have adversely affected the vigor of grasslands, thereby allowing creation of more bare areas, increased germination of tussock seedlings, and reduced competitiveness of more desirable species. Kangaroo overgrazing in some nature reserves has also increased the area of bare ground. This may indicate that expenditure on serrated tussock control is going to increase in response to climate change.

3. Willows (Salix spp.) (must be suppressed/prohibited; except for permitted species)
Condition Willows are established along all ACT waterways except at higher altitudes. Most are classified as weeds of national significance. Willows spread by vegetative reproduction (where pieces of a plant break off or are transported by machinery and later take root), seeds (where separate male and female willows pollinate) and planting. A major problem with willows and a significant factor in their rapid spread is that there are now many types of willows resulting from the crossing of different species. These willow hybrids are generally fertile, difficult to identify and some have superior survival to their parents (Cremer 1999). There is now concern that even the permitted willow species can hybridise with other species (CRC for Australian Weed Management 2003, Molonglo Catchment Group 2006).
Impacts Willows affect habitat, water quality and stream flow and may also constrain and present a hazard to recreational activities. Where they form the primary stream bank habitat, their removal should be accompanied by revegetation with suitable species.
Response Willow control has been conducted using a 'top of the catchment down' approach with control programs concentrating on the various tributaries of the major ACT river systems. Control has proceeded progressively down the major catchments resulting in significant control of willows in some catchments, with Ginninderra and Jerrabomberra creeks being the most notable examples. Some sections of the Murrumbidgee and Molonglo river systems have been treated, however the Molonglo River remains largely untreated except for the upper section near Molonglo Gorge. The Lake Burley Griffin Willow Management Plan (Molonglo Catchment Group 2006) provides significant guidance for control of willows along the Molonglo River and Lake Burley Griffin.
Status and outlook Willow control is a major ongoing problem exacerbated by the rapidly evolving biology of the willows, difficulties with their identification, their ability to spread rapidly in vast numbers, the sensitivity of the environments in which they establish, and the difficulty and expense of control work (Cremer 1999, Molonglo Catchment Group 2006). In providing information for this report, the ACT Department of Territory and Municipal Services has advised that capital works funding will be sought to address the most significant willow infestation in the ACT, which is along the Molonglo River. Other control programs include initial work to poison and fell willows in the Lower Cotter Catchment (from Blundells wetlands, Condor Creek, Lees Creek and Pierces/Dry Creeks) and follow-up control on Jerrabomberra and Ginninderra creeks.

4. African Lovegrass (Eragrostis curvula) (must be contained)
Condition African Lovegrass continues to be of concern, particularly because of its encroachment into urban areas of Canberra. The most common form appears to be spread by grass slashers and mowers. A tall variety of African Lovegrass has emerged as a serious pest plant in recent years.
Impacts African Lovegrass is a widespread environmental and agricultural weed. It is an invasive, tenacious, drought and frost tolerant species capable of dominating the ground flora on lighter low-nutrient soils (Muyt 2001).
Response Slasher and mower operators have been given training with a view to reducing further spread by machinery. There has been a major focus to control the species on rural roadsides. Control programs for the tall variety were increased on rural roadsides and in the Belconnen area in 2006–07, following relatively small and non-strategic programs in previous years.
Status and outlook Given the widespread nature of this species in the urban environment, the priority to undertake widespread control has been replaced by containment. Control on rural roadsides and efforts to maintain hygiene practices with machinery will be continued.
Many part of Canberra Nature Park are predominantly grassy ecosystems (native grasslands and grassy woodlands) that are susceptible to invasive grass weeds, such as African Lovegrass. Control from within the nature reserves through any neighbouring land or to roadsides, will be essential to establish the long-term integrity of these reserves.
African Lovegrass control requires a combination of herbicide spraying, regeneration/re-seeding and a change to existing mowing/slashing practices. Mowers easily spread African Lovegrass (and other invasive species) from infested areas to clean sites. Roadside mowing has resulted in a dramatic increase in its spread. Roadsides adjacent to nature reserves and weed free areas should only be mowed with thoroughly clean machines. If the mower cannot be thoroughly cleaned, separate mowers should ideally be used in clean areas only rather than infested areas. One way to implement this is to establish a new mowing contract solely for mowing outside reserves. Such a change to current mowing programs could dramatically increase the cost of amenity mowing.

5. Chilean Needle Grass (Nassella neesiana) (must be contained)
Condition Chilean Needle Grass is widespread throughout urban Canberra and common in some rural areas. Contaminated mowers and slashers move it from nature strips to roadsides adjacent to reserves. It can then spread into the nature reserves by seeds attaching to animals, people and vehicles.
Impacts The species is more common and abundant in urban areas and is not easy to recognise. It is a threat to native grassland and grassy woodland.
Response Sites with high conservation value sites in the urban area have been targeted for control. An awareness and education program to identify and manage this weed has been continued. Mowing activities have been restricted during seeding periods in areas close to urban native grassland sites. Treatment of Chilean Needle Grass has been undertaken in the Gungahlin Grasslands Reserve, Watson Woodlands, and the Black Mountain, Red Hill, Mount Pleasant, Mount Ainslie and Mount Majura nature reserves. Extensive roadside verge treatment along the Barton Highway, Gungahlin and Kuringa Drive and in the Mitchell area has been undertaken in an effort to stop the spread into the Gungahlin region and some urban native grassland sites. Unfortunately this spraying has failed to stop the spread, probably because mowers and slashers move the grass seed from infested areas to clean sites, where new infestations commence.
Status and outlook The species is well established in the urban area and its eradication is unlikely. In providing information for this report, the ACT Department of Territory and Municipal Services has advised that targeted control will be continued around the native grassland and woodland reserves and that awareness raising and education programs will also continue.
The comments about improving mower/slasher practices for African Lovegrass also apply to Chilean Needlegrass.

6. Blackberry (Rubus fruticosus agg.) (must be contained)
Condition Blackberry is widespread and required considerable control effort after the 2003 bushfires.
Impacts It is invasive of native bushland, riparian areas, farmland and production forest areas.
Response Following the 2003 bushfire, blackberry infestations have been treated in a number of Canberra Nature Park reserves, the Murrumbidgee River Corridor, Namadgi National Park and in pine plantations at Pierces Creek and Uriarra. The latter was part of pre-plant preparations and also included a number of high conservation value sites within the former ACT Forests estate.
An extensive control program was implemented at the former ACT Forestry Block 60 (Jedbinbilla) adjacent to Tidbinbilla Nature Reserve and also in the Lower Cotter Catchment. The scale of the works involved in controlling blackberry infestations in the burnt areas of the former softwood plantations was extremely large and beyond allocated resourcing levels. Control programs were directed at priority areas in the Lower Cotter Catchment and establishing buffers along some rural lease boundaries. The 2007–08 spraying program proved highly successful as the above average rainfall allowed vigorous Blackberry growth, which makes herbicides more effective. The new proposed Weed Ecologist will make quantitative measurements of the program's long-term success.
Status and outlook A rust strain for biological control was released in the Cotter catchment in 2006. Further releases in cooperation with the CSIRO are planned for an additional six to 10 sites located strategically throughout the ACT, including the former pine plantation areas. Even with this biological control, Blackberry will, for the foreseeable future, continue to be a significant pest plant in the ACT. A large percentage of infestations will remain untreated primarily due to the scale of the works required for their control. A high priority for Blackberry control will be 250 hectares of land in the Lower Cotter Catchment (including areas to be revegetated, roadsides and high quality wetland areas and known as Blundells, Sinclair Circuit, Bullock Paddock East and West, Pabral and Uriarra/Lower Cotter).

7. African Boxthorn (Lycium ferocissimum) (prohibited/must be suppressed)
Condition A concentrated but generally low-density infestation of African Boxthorn is growing in the Fyshwick and Pialligo areas.
Impacts The shrub is highly invasive once established and has long, strong spines requiring careful handling.
Response Control programs have been undertaken on this species using small rubber tracked earthmoving equipment; however, not all landholders with infestations have participated in this work.
Status and outlook In providing information for this report, the ACT Department of Territory and Municipal Services has advised that control work will be continued as needed with attention to the participation of all affected landholders.

8. Broom and gorse:
Broom (Cytisus and Genista ALL species) (prohibited/must be suppressed)
Spanish Broom(Spartium junceum) (prohibited)
Gorse (Ulex europaeus) (prohibited/must be suppressed)
Condition Broom and gorse are found throughout the ACT. Infestations in residential areas continue to be a major problem.
Impacts Broom and gorse commonly invade forest, woodland and river corridors.
Response Control of these species is given a very high priority. All known broom and gorse infestations have been controlled during the reporting period. However, previously unknown infestations continue to appear periodically and are included in the annual control program.
Status and outlook Sale of these species through retail outlets is prohibited, but the plants often appear for sale at fetes and markets and therefore, from a regulatory perspective, continue to be of some concern. Education and awareness are the main means of addressing residential infestations and changing community attitudes to these pest plants.

9. Paterson's Curse (Echium plantagineum) (must be contained)
Condition Paterson's Curse is a winter annual that occurs across the ACT in both urban and non-urban areas. The species is drought resistant and infestations vary from year to year depending largely on late summer/autumn rainfall events.
Impacts The species is Australia's worst broadleaf temperate pasture weed and can be poisonous to stock, particularly horses and pigs.
Response Extensive growth of Paterson's Curse in the winter following the 2003 bushfire required increased control of the species. Control was undertaken in Canberra Nature Park reserves that adjoin rural leases used for horse agistment, in the ACT Government Horse Holding Paddocks, and along all ACT rural roadsides. High priority was given to control at all Department of Defence sites in the ACT specifically to protect important ecological areas.
The profile of Paterson's Curse was also raised through education and awareness programs primarily directed at ACT rural lessees with horse agistment enterprises.
Status and outlook A number of biological control agents have been released nationally for control of Paterson's Curse and these are now established in the ACT. They help contain infestations of Paterson's Curse, but control measures will still need to be taken, depending on seasonal conditions. The species is given a low priority for treatment except for infestations that have the potential to affect horse agistment enterprises or high conservation value areas.

10. St John's Wort (Hypericum perforatum) (must be contained)
Condition St John's Wort is a perennial herb, established across the Territory in many parts of Canberra Nature Park, in rural areas and in pine plantations.
Impacts The species is a major pasture weed, is toxic to stock, and invades grassy woodland. It is favoured by low intensity fire.
Response Large-scale control programs were undertaken in Canberra Nature Park, Googong Foreshores (NSW), Tidbinbilla Nature Reserve, and the Murrumbidgee and Molonglo River Corridors. Follow-up control was undertaken on rural roadsides and along major arterial roads throughout the ACT with particular emphasis on fire affected rural roadsides.
Status and outlook The species is widespread in the ACT and capable of colonising extensive areas. Control will need to be ongoing in identified priority areas. Recent prolonged dry periods have resulted in a reduction in growth and subsequent flowering of a large percentage of St John's Wort infestations throughout the ACT. The new Weed Ecologist will undertake quantitative measurement of the long-term success of this control work.

11. Woody weeds (for the purposes of pest plant control, this refers to a wide range of invasive non-herbaceous plants; most are declared pest plants)
Condition Woody weeds are widely established in the ACT. Some species that are now declared pest plants were widely used in gardens and landscaping until relatively recently. The presence of these plants facilitates their ongoing spread; for example, dispersal of seeds by birds, wind and water; suckering; vegetative propagation; and by gardeners using cuttings or seedlings. Many residents do not realise that common self-sown trees and shrubs are pest plant species; for example, Privet (Ligustrum spp.), Box Elder (Acer negundo), Cotoneaster (Cotoneaster spp.). Woody weeds include invasive native species. The best known in the ACT is Cootamundra Wattle (Acacia baileyana). The widespread presence of woody weed infestations in the ACT is a major concern. In some instances pest species are part of the existing landscaping of government buildings and public places.
Impacts Woody weeds invade reserves, parkland, suburban backyards and rural land. In some areas, such as riparian areas and lowland woodland, dense woody weed thickets may establish over time.
Response A woody weed management program has been in place for a number of years, involving removal of infestations, removal of landscaping features such as Cotoneaster hedges, cooperative work with nurseries (the 'bush friendly nursery' scheme), weed swap days, and preparation and dissemination of information material such as the brochure Are Your Garden Plants Going Bush?
Examples of recent work under this program include Pyracantha and Cotoneaster hedge removal in Lyneham, follow-up control work along Yarralumla Creek, removal of extensive areas of Poplar suckers in Monash and Belconnen, removal of infestations of a range of species at Oaks Estate, near Yarralumla Nursery, along Lady Denman Drive and at various suburban locations. After the 2003 bushfires, herbicide was issued to rural lessees to control woody weeds in fire-affected areas. Woody weed control was also undertaken in several fire-affected areas managed by Parks, Conservation and Lands. There have also been good results in reducing the cover of woody weeds in the Gudgenby valley of Namadgi National Park and the southern part of Googong Foreshores (NSW).
Status and outlook Control of woody weeds is an ongoing task as problem species are well established throughout the ACT and have effective dispersal mechanisms. All the major pest plants are now listed as prohibited under the Pest Plants and Animals Act 2005 and cannot be sold legally from retail outlets. The ACT nursery industry has been very cooperative in abiding by these restrictions. In providing information for this report, the ACT Department of Territory and Municipal Services has advised its intention to continue woody weed control programs aimed at limiting the spread of problem species, as well as removing established infestations and sources of new infestations.

12. Pine wildlings in the Lower Cotter catchment
Condition Pine wildlings are widely established in the former pine forest areas within the Lower Cotter catchment and are a major concern.
Other infestations across the former forest estate present their own problems, but these are not seen as such a high priority at this stage.
Impacts The presence of these plants facilitates their ongoing spread and competes with native regeneration for light and nutrients. In some areas, such as riparian areas and lowland woodland, dense pine thickets may establish over time.
Response The strategy is to remove pine wildlings from the majority of the Lower Cotter Catchment. The only exceptions are isolated pockets where access is not safe due to standing dead pines, and in the Blue Range area where very high densities make manual control uneconomic. As at the end of 2007, around 600 hectares remained to be treated before the entire area will be covered a second time to remove pines that have emerged in the intervening period.
Examples of recent work under this program include removal of pine wildlings by manual labour from 2300 hectares of former plantations at Pierces Creek and Uriarra forests including in riparian zones, and planting over 350,000 native tubestock to replace over 400 hectares of pine wildlings that were removed from former pine plantations.
A possible control method in the future will be use of fire, subject to ability of the native vegetation to withstand the fire.
Status and outlook Control of pine wildlings is an ongoing task as they are well established in the former pine forest areas. Pinus radiata is now listed under the Pest Plants and Animals Act 2005. Significant progress has been made in removing pines from large areas, and there is now a sound basis for control. The need for follow up control is recognised and funding has been allocated for this purpose for the period 2007–10.  While pines are unlikely to be eradicated, the level of control effort will continue to be high.

Data sources and references

ACT Department of Urban Services 1996, ACT Weeds Strategy – a 10-year (1996–2006) strategy for implementing a coordinated program for controlling weeds in the ACT, ACT Department of Urban Services, Canberra

ACT Government 2004, Woodlands for Wildlife: ACT Lowland Woodland Conservation Strategy, Action Plan No. 27, Environment ACT, Canberra 2004 available at <>

ACT Government 2005, A Vision Splendid of the Grassy Plains Extended: ACT Lowland Native Grassland Conservation Strategy, Action Plan No. 28, Environment ACT, Canberra 2005 available at <>

ACT Government 2007, Ribbons of Life: ACT Aquatic Species and Riparian Zone Conservation Strategy, Action Plan No. 29, Environment ACT, Canberra

Australian State of the Environment Committee 2006, Australia State of the Environment 2006. S. 5.2 Pressures on Biodiversity: Weeds and Feral Animals, Commonwealth of Australia, Canberra

CRC (Cooperative Research Centre) for Australian Weed Management 2003, Weed Management Guide Willow – Salix spp., Department of Environment and Heritage, Canberra available at <>

Cremer K 1999, Willow management for Australian rivers, Natural Resource Management (Special Issue) December 1999, pp. 2–22

Molonglo Catchment Group 2006, Lake Burley Griffin Willow Management Plan, Prepared by Greening Australia Capital Region on behalf of the Molonglo Catchment Group, Canberra

Muyt A 2001, Bush Invaders of South-East Australia, RG and FJ Richardson, Meredith, Victoria

NRMMC (Natural Resource Management Ministerial Council) 2006, Australian Weeds Strategy: A national strategy for weed management in Australia, available at <>

TAMS (Department of Territory and Municipal Services) 2007, Draft ACT Weeds Strategy 2007–17, Environment and Recreation, Department of Territory and Municipal Services, Canberra


The Commonwealth Ministers for Forestry and Conservation; Agriculture, Fisheries and Forestry; and the Environment jointly announced the inaugural list of weeds of national significance on 1 June 1999. The process of determining weeds of national significance is published in The Determination of Weeds of National Significance by JR Thorp and R Lynch and is available at See also, <>

living sustainably

Click to expand sitemap