PART 6 – WEED LISTS
Whatever means of weed risk assessment is adopted, from a management perspective the outcome is the same – a list of plants that must be dealt with in some way. What kinds of lists are available and how reliable are they?
Some lists are statutory; they are legally binding. Others have governmental or scientific authority; but these lists are relatively few. How are we to assess and respond to the many others?
Some plants are considered so invasive that they pose a serious threat almost anywhere they might be grown; they have a broad ecological amplitude. Others may be devastating weeds but only under a narrow range of conditions.
In the desire to establish firm guidelines for weed management it is tempting to compile “definitive” lists for management action. Lists like this should be tempered with the knowledge that plants behave differently in different areas: the degree of environmental and/or agricultural risk posed by a given plant will vary from place to place. These points have already been mentioned:
• Lists are directed at different levels of the ecological hierarchy – global, national, state, regional, or local – we need to know the geographic/bioregional scope of the list
• We need to have some estimate of the degree of risk posed by plants
• The degree of risk posed by any plant will depend on where it is growing
The list of Australia’s 20 worst weeds, the WONS, appear appropriate for total exclusion from cultivation in this country. And yet it might be pointed out that Australia’s worst weed, Parkinsonia aculeata, Parkinsonia, from tropical America, is not naturalised in Victoria and, being a tropical plant, would pose little or no threat if grown there. In such a case it may be also be pointed out that this is such a devastating weed where it does grow, that cultivation anywhere might only increase the probability of it being transported accidentally or deliberately to new sites. This situation becomes even more important when we are considering growing potentially devastating weeds that are not yet established in our region. A current illustration of this exists where plants that are declared weeds in one state are readily available in nurseries just across their borders 58. Clearly for legislation to be effective a nationally coordinated approach to the problem is called for and at least adjacent states could be cooperating with one-another and coordinating their efforts.
But what if the tropical plant in question were not a devastating weed but only a minor one, and we wanted to grow it in southern Australia? There is no simple answer here. Ultimately decisions must be based on estimated risk.
High risk plants
It would be a great advantage if the lists: global, national, state, regional, local represented a nested hierarchy of plants posing high (unacceptable) risk, that the plants in a list at any level of the hierarchy also include all those in the levels above. So, weed management would be assisted if a list of global weeds were compiled of those plants considered to pose such a serious threat (no matter where they are grown) that they should be banned or seriously discouraged. Such a list would be based on the best WRA achievable. A national list would then be compiled in the same way and would, of course, include all the plants on the global list. This process could then proceed down the hierarchy. It should be noted that some plants on the global list may not be in the country, but that only emphasises their high potential threat.
Further lists could be assembled to indicate plants with moderate risk, and so on. Of course these lists would be less authoritative and allow
The Global Invasive Species Database
The Global Invasive Species Database (GISD) aims to improve awareness of all invasive alien species just plants) and to encourage their effective management. It is managed by the Invasive Species Specialist Group (ISSG) of the Species Survival Commission of the IUCN-World Conservation Union. The GISD was developed as part of GISP. The focus is on species that threaten native biodiversity and its scope is all taxonomic groups from micro-organisms to animals and plants in all ecosystems. Species information is either supplied by or reviewed by expert contributors from around the world. It is being constantly updated.
The world’s worst agricultural weeds
A 1977 publication 65 lists the 18 most serious agricultural weeds world-wide, in approximate order of impact, as:
Cyperus rotundus, Nutgrass (world’s worst weed) Sorghum halepense, Johnson Grass
Cynodon dactylon, Couch Imperata cylindrica, Blady Grass
Echinochoa crusgalli, Barnyard Grass Chenopodium album, Fat Hen
Echinochloa colonum, Awnless Barnyard Grass Digitaria sanguinalis, Summer Grass
Eleusine indica, Goose-grass Convolvulus arvensis, Field Bindweed
The above “top ten” is distinguished by being clearly the most widespread with the greatest impact on the largest number of crops. The remaining eight are:
Portulaca oleracea, Purslane Amaranthus hybridus, Pigweed
Eichhornia crassipes, Water Hyacinth Cyperus esculentus, Nut Sedge
Avena fatua, False Oats Paspalum conjugatum, Ti Gras, Sour Grass
Amaranthus spinosus, Spiny Amaranth Rottboellia exaltata, Corn Grass, Itch Grass
The Global Compendium of Weeds
The Gobal Compendium of Weeds is a compilation of plants known to have naturalised somewhere in the world. This project is an extension of the Exotic Species Database for Australia compiled by Rod Randall 99, supported by the CRC for Australian Weed Management and nearing completion in 2006. From the Exotic Species Database database which has been compiled from nursery stock lists, a botanic gardens plant inventory, books, pamphlets etc. it is estimated that 27,338 species of exotic plants have been introduced to Australia, numerically about 40% more than those species naturally present. It is also estimated that a total of about 36,414 species are found in cultivation, to some extent, somewhere in the country of which 25,714 are exotics and 10,700 natives. Of the 672 natives that have naturalised outside their native range 591 (88%) are also cultivated. Of the 24,249 introduced species that have not naturalised there are 4565 with records of naturalisation elsewhere in the world. The final form of the database is not decided but it is expected that one version will be a PDF document and another a delimited file that can be imported into any database. Both will be available from the CRC for Australian Weed Management.
A recent publication provides descriptions of over 400 species of the world’s major environmental weeds 75
Invasive Plants of National Importance
Invasive Plants of National Importance (IPNI) have have been defined as those invasive plants that the Australian Government should have an interest, in cooperation with the States and Territories, to ensure a robust nationally coordinated and effective prevention, eradication and control response 33.
The only national list of invasive species accepted collectively by the Australian, State and Territory governments is the 20 species listed on the WONS (see below). In the absence of a more comprehensive list the WWF has compiled a set of lists that are either official government lists, or lists recommended by scientists. These lists were divided into three categories:
Species that are a high invasion risk, some present already.
1. Northern Australia Quarantine Strategy Weed Target List
Northern Australia Quarantine Strategy Weed Target List (NAQS) is a list of 41 species that are regarded as serious threats to Australia’s productivity, export markets and the environment (available on the site www.affa.gov.au).
Naturalised invasive species currently within a restricted range and whose eradication is feasible and cost-effective.
1. Commonwealth Alert List of Environmental Weeds
In 2000, the Department of the Environment and Heritage worked with experts to identify plant species that are in the early stages of establishment and have the potential to become a significant threat to Australian biodiversity if not managed. Those species that were identified have been placed on the National Environmental Alert List. The Commonwealth Alert List of Environmental Weeds (CALEW)42 list is made up of 28 non-native weeds that have established naturalised populations in the wild.
Scientific Name Common Name (Where Known) Extent In Australia Potential Distribution
Acacia catechu var. sundra Cutch tree NT QLD, WA
Acacia karoo Karroo thorn QLD, NSW, SA, WA
Asystasia gangetica ssp. micrantha NSW QLD, NT, WA
Barleria prionitis Barleria QLD, NT WA
Bassia scoparia (weedy form) Kochia Tas, WA NSW, Vic, SA
Calluna vulgaris Scotch heather Tas NSW, Vic
Chromolaena odorata (weedy form)
Siam weed QLD NT, WA
Cynoglossum creticum NSW Vic, Tas, SA, WA
Cyperus teneristolon NSW QLD, Vic, SA, WA
Cytisus multiflora White spanish broom Vic NSW, Tas, WA
Dittrichia viscosa WA NSW, Vic, Tas, SA
Equisetum spp. Horsetail NSW, Tas, Vic
Gymnocoronis spilanthoides Senegal tea plant QLD, NSW
Hieracium aurantiacum Orange hawkweed, orange paintbrush
Tas, Vic NSW, SA
Koelreuteria elegans Chinese rain tree, flame gold,golden rain tree
QLD NSW, NT, WA
Lachenalia reflexa Lachenalia WA NSW, Vic, Tas, SA
Lagarosiphon major Lagarosiphon Tas, NSW Vic, SA, WA
Nassella charruana Vic NSW, SA, WA
Nassella hyalina NSW, Vic
Pelargonium alchemilloides WA NSW, Vic, Tas, SA
Pereskia aculeata Leaf cactus QLD, NSW WA
Piptochaetium montevidense Vic NSW, SA, WA
Praxelis clematidea QLD NT, WA
Retama raetam White weeping broom SA, WA NSW, Vic, Tas
Senecio glastifolius Holly leaf senecio, water dissel
NSW, WA,Vic, Tas, SA
Thunbergia laurifolia Laurel clock vine QLD NT, WA
Tipuana tipu QLD NT, WA
Trianoptiles solitaria Vic NSW, Tas, SA, WA
Also available at www.deh.gov.au/biodiversity/invasive/weeds/alert-list.html
2. Candidate eradication and containment list impacting natural ecosystems
This 3 is a list of 34 naturalised species compiled by scientists to include species that pose a direct threat to natural ecosystems because of their potential impact on native species: it has no official status.
3. Candidate eradication and containment list impacting agricultural ecosystems
This3 is a list of 27 naturalised species compiled by scientists to include species that pose a potential threat to agricultural ecosystems should they ever spread further: it has no official status.
4. Bureau of Rural Sciences eradication candidate list of sleeper agricultural weeds
A list 66, compiled by scientists, of 17 species for cost-effective eradication before they become major agricultural weeds: it has no official status.
Invasive species that are naturalised and widespread, pose a major threat to the environment or agriculture and whose containment or control will protect values of national environmental significance.
Weeds of National Significance
To implement the NWS it was decided to rank weed problems of national significance. The National Weeds Strategy Executive Committee was established in 1997. The Committee concluded that the greatest impact from weed problems within Australia was related to the effect and spread of specific individual species. On this basis, the assessment procedure developed would focus on determining Weeds of National Significance (WONS) 17, 43 and prioritise weeds over a range of land uses at the national level in an attempt to draw together meaningful indicators for future weed decision-making as well as a method for prioritising weeds at the State, regional and local levels17. The selection of twenty WONS is a test case for improved coordination among stakeholders responsible for weed management within Australia. The list below is ranked in order of importance. Figures in brackets are the percentage of land surface occupied by each weed, the total Australian land area occupied being 70.9% 17.
1 Parkinsonia aculeata Parkinsonia (12.4) 11 Cabomba caroliniana Cabomba (0.5)
2 Prosopis spp. Mesquite (5..3) 12 Nassella neesiana Chilean Needle Grass (0.2)
3 Rubus fruticosus spp. agg. Blackberry (9.0) 13 Tamarix aphylla Athel Pine (1.0)
4 Lantana camara Lantana (5.1)
14 willows except weeping willows, pussy willow and sterile pussy willow Salix spp. except S. babylonica, S. X calodendron and S. X reichardtii (0.8)
5 Cryptostegia grandiflora Rubber Vine (7.7) 15 Nassella trichotoma Serrated Tussock (2.2)
6 Chrysanthemoides monilifera Boneseed (3.0)
7 Acacia nilotica ssp. indica Prickly Acacia (2.3) 16 Parthenium hysterophorus Parthenium Weed (5.6)
8 Hymenachne amplexicaulis Hymenachne (1.0) 17 Annona glabra Pond Apple (0.4)
9 Salvinia molesta Salvinia (5.0) 18 Ulex europaeus Gorse (3.0)
10 Mimosa pigra Mimosa (1.0) 19 Asparagus asparagoides Bridal Creeper (5.0)
20 Alternanthera philoxeroides Alligator Weed (0.4)
The list of WONS is available at www.deh.gov.au/biodiversity/invasive/weeds/wons.html
A document addressing management strategies for WONS is available at:
Land areas occupied by transformer weeds in Australia 40 cited in 39
INVADER AREA OCCUPIED (ha.)
Rubus fruticosus spp. agg., Blackberry 8 M
Acacia nilotica subsp. indica, Prickly Acacia 6.6 M
Lantana camara, Lantana 4 M
Cryptostegia grandiflora, Rubber Vine 700 000 (over 20% Qld)
Mimosa pigra, Mimosa, Sensitive Tree 80 000
Each State has lists of declared weeds. In Victoria further restricted lists may be produced (see Declared Weeds, Part 1).
Regional and local – Bushland Friendly Gardens
The Weeds CRC has a web page on Bushland-friendly Gardens that synthesises published weed information for 22 “clickable” climatic regions of Australia that are recognised by the horticultural industry (www.weeds.crc.org.au/bushlandfriendlygardens). Master lists of weeds for each region were compiled by synthesising existing lists and brochures of problem plants in that region using the assumption that the more lists on which a plant appears, the more it is likely to impact. Each region generates two lists of commonly available garden plants that should be avoided in the selected region. Where a plant species appeared on three or more regional lists it was placed into the ‘serious environmental weeds’ list – these being plants to be removed as soon as possible. If a plant appeared twice, it was placed on the ‘environmental weeds to avoid’ list – recommended not to be planted, or at least managed with great care. The Weed CRC believes that the final weed lists for each region are a fair representation of the potential and actual impacts for each species. The site has a bibliography of regional lists and also indicates literature that suggests alternative species to plant.
CURRENT MANAGEMENT PRACTICES
Tackling invasive plants, as with many pervasive ecological problems, requires an integrated and coordinated approach at many levels; from global to local, industrial to scientific.
Management in the field
Like the weeds in our gardens, environmental and agricultural weeds require management. The broad plan of action is prevention, containment, control and eradication. This means early detection and rapid response, ideally by preventing their occurrence but, if they have established, controlling them using environmentally safe methods – chemical, mechanical, biological etc.
Effective weed risk management (WRM) in the field is hampered by the multiplicity of land-holders, both public and private, together with the many additional organisations that have indirect influence over this land. Clearly a coordinated effort is needed. In Victoria for example organisations whose activities can influence the weed flora include: the nursery industry, Parks Victoria; Victorian Catchment Management Council and the Catchment Management Authorities; Victorian Farmers Federation; private landholders; VicRail and so on. One current difficulty is the integration of weed mapping into a common system acceptable to the various stakeholders. Procedures and methods used to reduce the impacts of weeds include:
For potential new weeds not yet in the country:
• preventing the entry of weed species into Australia (border protection – Biosecurity Australia)
For new arrivals, minimising their spread by :
• early detection and eradication of those both in the wild, and in cultivation (agriculture and the horticulture industry)
For established weeds:
? using existing control measures such as herbicides (world-wide herbicide weed resistance in crops began 1970-1980), cultivation, and biological control
These key procedures are supported in the following ways:
• legislation to control movement of weeds; and
• research including development of new detection and eradication methods
• campaigns to educate the public and industry
• national coordination
Clearly prevention is better than the expensive control and eradication programs that are necessary once weeds become established. Historically government has been reactive, responding to weed problems as they have arisen. It is now urgent that we become proactive, ensuring that potential weeds are refused entry into Australia and that the demand, supply and control of those already present is closely monitored.
As with many other ecological problems the management of invasive plants must be tackled at all levels of governance, from global to local and organisational. Individuals must also accept that they have a role, no matter how small.
Establishing a global and national framework of intention gives guidance and authority to the groups who deal directly with the weeds.
Where weeds are well established through most of their potential range resources are best directed to eradication of early invaders rather than attempting eradication or banning their availability. Figure 6 illustrates the typical pattern of invasive weed spread, indicating the cost-benefit of tackling eradication or control early in the invasion process.
Figure 6 – Pattern of weed spread
Prioritising for management
In assessing the allocation of resources to weed management it is clearly important to assess costs against potential benefits. A plant that has spread throughout its potential range is a lesser priority than a potentially invasive plant that is newly arrived. Weed risk assessment follows the three key parameters by considering: invasiveness (how fast-spreading is it?), potential distribution (is it localised at present but could spread over a wide area?), impacts (what is its potential for adversely impacting of social, environmental or agricultural values?).
The Weed CRC together with CSIRO scientists and Prof Ed Newbigin of Melbourne University Botany Department in August 2005 announced a research program aimed at producing a non-toxic spray that mimics chemicals produced by the plant itself to prevent self-fertilization. This is generally a protein that allows the plant to detect and ignore its own pollen. It therefore acts like a chemical contraceptive. Work would begin on the agricultural weed Raphanus raphanistrum, Wild Radish, and results were expected within three years 81.
In 2000 a draft national strategy on invasive garden plants called Garden Plants Under the Spotlight20 (GPUTS) was produced by the Weeds CRC with State Government agencies and the Nursery Industry Association of Australia NIAA (now Nursery and Garden Industry Australia, NGIA). It made a number of recommendations for raising industry and community awareness about invasive garden plants and strengthening legislation. Weed work continues at NGIA with: the development of an Invasive Plants policy Position including a commitment to developing industry-based communications and awareness programs; appointment of an Environmental Policy Manager; accreditation programs, Technical Nursery Papers 19,20,110 and newsletters, articles etc.; ESM programs; “Grow Me Instead!” pamphlets; cooperation with other organisations.
From this strategy, a list of 52 ‘Garden Thugs’ was assembled with the intention that they be removed from trade around Australia voluntarily 19. The strategy has not been finalised.
GARDEN THUGS 19
Ailanthus altissima Tree of Heaven Allium triquetrum Angled Onion
Alternanthera philoxeroides Alligator Weed Anredera cordifolia Madeira Vine
Arundo donax Giant Reed Asparagus asparagoides Bridal Creeper
Asparagus scandens Asparagus Fern Cabomba caroliniana Cabomba
Chrysanthemoides monilifera Boneseed Cortaderia spp. Pampas grass
Cotoneaster spp. Cotoneaster Crocosmia x crocosmiiflora Montbretia
Cryptostegia grandiflora Rubber Vine Cytisus scoparius English Broom
Delairea odorata Cape Ivy Dipogon lignosus Dolichus Pea
Eichhornia crassipes Water Hyacinth Elodea canadensis Canadian Pondweed
Equisetum spp. Common Horsetail Erica lusitanica Spanish Heath
Genista monspessulana Cape Broom Hedera helix Ivy, English Ivy
Hydrocotyle ranunculoides Water Pennywort Hypericum perforatum & vars St John’s Wort
Ipomoea indica Purple or Blue Morning Glory Lagarosiphon major Oxygen Weed
Lantana camara Lantana Leycesteria formosa Himalayan Honeysuckle
Mimosa pigra Mimosa Myriophyllum aquaticum Parrot’s Feather
Opuntia spp. (not Opuntia ficus-indica, Cylindropuntia spp., Tephrocactus spp.) Prickly Pear
Parkinsonia aculeata Parkinsonia Pinus radiata Monterey Pine
Pittosporum undulatum Sweet Pittosporum Polygala virgata Purple Broom
Prosopis spp. Mesquites Rosa rubiginosa Sweet Briar, Eglantine
Salix cinerea Grey Sallow Salix fragilis var. fragilis Crack Willow
Salix nigra Black Willow Salix rubens Willow
Salix hybrids Willow Salix x sepulcralis Willow
Salvinia molesta Salvinia Senna alata Candle Bush
Sparaxis bulbifera Harlequin-flower Tamarix ramosissima Saltcedar
Tamarix aphylla Tamarisk Tradescantia albiflora Wandering Jew
Ulex europaeus Furze, Gorse Watsonia bulbifera Bulbil Watsonia
Ziziphus mauritiana Chinee Apple
This list was no doubt given impetus by a list of 958 “garden thugs” eventually published by Randall in 2001 48.
In Victoria DPI is currently working with the Nursery and Garden Industry of Victoria (NGIV) to produce a list of invasive garden plants that may be restricted and removed from sale (Daniel Joubert, DPI Frankston pers. comm.). A ‘Voluntary List’ of about 58 plants has been agreed between the NGIV and the State Government as a recommendation for members not to grow or sell (see below).
Botanical Name Common Name
Acacia nilotica * Prickly Acacia
Ambrosia spp. All Ragweeds
Annona glabra.* Pond Apple
Anredera cordifolia Madeira Vine
Asparagus asparagoides * Bridal Creeper
Bassia scoparia , B. sieversiana , Kochia alata, K. scoparia var.
culta, K. scoparia var. pubsecens , K. scoparia var. subvillosa
Moq., K. scoparia var. trichophila (Stapf), K. sieversiana , K.
trichophila Stapf. Kochia
Cabomba spp. (all) * Cabomba
Calystegia silvatica Greater Bindweed
Carthamus glaucus Glaucous Start Thistle
Cenchrus incertus Spiny Bluegrass
Centaurea maculosa Spotted Napweed
Chromolaena odorata Siam Weed
Cryptostegia grandiflora* Rubber Vine
Disa bracteata African Weed-orchid
Gymnocoronis spilanthoides Senegal Tea
Hedera helix English Ivy
Hymenache amplexicaulis * Hymenache
Hypericum calycinum Grow under permit Large Flowered St John’s Wort
Hypericum canariense Canary Island St John’s Wort
Hypericum humifusum Grow under permit Trailing St John’s Wort
Lantana camara* Lantana
Miconia spp. * Miconia
Mimosa pigra * Giant Sensitive Plant
Nassella spp.* Needlegrass
Onopordum spp. Onopordum Thistles
Onopordum tauricum Taurian Thistle
Opuntia aurantiaca Tiger Pear
Parkinsonia aculeata* Parkinsonia
Rubus alceifolius Giant Bramble
Rubus argutus Florida Blackberry
Rubus rugosus Keriberry
Sagittaria graminea Sagittaria
Sagittaria montevidensis Arrowhead
Sagittaria platyphylla Delta Arrowhead
Sagittaria pygmaea Dwarf Arrowhead
Salix aegyptiaca * Asian sallow
Salix alba * White willow
Salix cinerea * Common Sallow
Salix exigua * Sandbar Willow
Salix fragilis. * Crack Willow
Salix glaucophylloides * Dune Willow
Salix humboltiana * Pencil Willow
Salix spp. (all except S. babylonica L., S. calodendron [= S. x
calodendron = S. caprea x S. purpurea x S. viminalis, S. x reichardtii
[= S. caprea x S. cinerea, S. alba var caerulea ) * Willow, sallow, osier
Salix matsudana * Tortured Willow
Salix nigra * Black Willow
Salix purpurea and cultivars * Purple Osier
Salix seringeana * Seringe Willow
Salix viminalis * Basket Willow
Salix x chrysocoma * Golden Weeping Willow
Salix x dasyclados.* Willow
Salix x pendulina. * Wisconsin Weeping Willow
Salix x rubens * White Crack Willow
Salix x sepulcralis. * Weeping Willow
Salvinia. spp. (all) * Salvinia
Scolymus maculatus Spotted Thistle
Tamarix aphylla * Athel Tree
* Plant is Weed of National Significance (WONS)
A number of additional Nursery Papers have been produced covering such topics as advising the public about weeds, providing alternatives to garden escapes, and preventing the introduction of new weeds: these can be accessed from the NGIA web site. A Fact Sheet for the horticultural media is available from www.weeds.crc.org.au.
Sustainable Gardening Australia
One response by the nursery industry has been the formation, in 2004 of Sustainable Gardening Australia (SGA). SGA is a not-for-profit association totally committed to achieving real, continually improving and easily understood environmental solutions for gardeners. Nurseries and Garden Centres on the SGA program have voluntarily removed from sale 10 of the worst weed invaders of their area and are also encouraged to tag other potentially invasive plants with “SGA Weed Warning” labels. Included in the work of SGA are a Green Gardeners course with Holmesglen TAFE and the landscape industry (inc. certification for designers and landscapers); an online course in Sustainable Gardening.
Bushland Friendly Nursery Scheme
On the Northern NSW coast a Bushland Friendly Nursery (BFN) Scheme has been introduced and there is the possibility of the scheme a national program. The schemes establish weed lists for the local area, specifying plants that should not be sold, propagated or knowingly distributed. Unfortunately such a system based on goodwill can be easily abused by introduction of plants from elsewhere.
For many years Botanic Gardens were part of an international network exchanging seed lists (Index Semina) – this being the main means of plant acquisition, especially the rare and unusual species. Seed exchange is now restricted. Firstly, there is the legally binding Convention on International Trade in Endangered Species of Wild Flora and Fauna (CITES). Secondly, under Article 8 of the 1993 Convention on Biological Diversity (CBD) national governments are called on “to prevent the introduction of” and “control or eradicate those alien species which threaten ecosystems, habitats or species”. The Global Invasive Species Program (GISP), was established in 1997 to address the global threat and support the implementation of Article 8 of the CBD. As a result of these international initiatives there is now a common agreement among many botanic gardens to carefully monitor the acquisition and use of genetic resources, one aspect of which is obtaining consent from the country and/or organisation of origin to ensure potential benefit sharing (including non-monetary benefits), this also being a requirement of the CBA.
The major Australian botanic gardens have not produced Index Semina for many years (the last seed list produced by the Royal Botanic Gardens Melbourne was in 1994) and seed acquisition from overseas is dealt with by special request and supervised with caution.
Historically there is no doubt that botanic gardens were a point of entry for plants new to the continent. The escape of Blackberry, Rubus fruticosus, and Sensitive Tree, Mimosa pudica, have been attributed to the Melbourne and Darwin botanic gardens respectively. Some of the newly acquired plants would have passed to public parks and gardens, the nursery industry and from there to home gardens.
Internationally botanic gardens are still in the early stages of developing WRA models. Chicago Botanic Garden has recently developed an invasive screening protocol using an integrative approach that combined regional invasive species lists, commercial availability, a WRA and on-site evaluation 60.
The Australian Botanic Gardens Weed Network
In October 2004 the Council of Heads of Australian Botanic Gardens (CHABG) endorsed a proposal for the collaboration of Australia’s Botanic Gardens in developing weed policies, management and weed risk assessment. A network of about 70 public gardens, zoos and arboreta has been established to achieve these objectives 102.
Plants posing high risk are removed altogether. Direct weed management strategies include: pruning, using barriers to roots, removing seed heads; not selling the plant or allowing it to be moved out of the gardens; restricting access to plants through the use of barriers and enclosures; use of signs to indicate weed problems and enforcement procedures e.g. signs at gates indicating that removing plants or parts thereof is a criminal offence.
The Municipal Association of Victoria encourages local councils to include invasive species management as part of their biodiversity conservation policies (see Victorian Local Government Weed Management Report: Programs, Resources and Management Approaches, 2003. www.mav.asn.au) also 98.
Voluntary community groups managing small areas of public land are working hard to monitor and manage the weeds on their sites. There is an excellent weed management manual prepared by the Weed CRC as a training aid for private landholders, conservation groups, catchment management groups, local, state and territory governments and industry available at
Ideas for preventing weeds in your area are given in the Suggestions for Home Gardeners. The “Bradley method” of weeding by starting in the least infested areas and working towards the greatest infestation has been an inspiration to many community groups when tackling what seems an insuperable task 87.
Another innovation has been the Plant Swap Meet, where pest plants are handed in by residents in exchange for native plants. Swap Meets have also been used successfully as part of a “Connect with Nature” campaign in New Zealand.
Weedbusters and Bushcare
Weedbusters is an awareness program that works with the community to achieve sustainable land and water management, primarily through increased public involvement in weed management, education and awareness projects. Weedbusters started in 1994 in Queensland, spreading to become national in 1997 with encouragement and support from the Australian governement, all State and Territory Governments and the Cooperative Research Centre (CRC) for Australian Weed Management. Weedbusters is now a year-long campaign, culminating in Weedbuster Week – a week of highlights and celebrations. The Weedbusters program has spread to New Zealand and South Africa, and other countries have expressed interest in running their own Weedbuster campaign. (see www.weedbusters.info)
Landcare groups are working on solutions to the degradation caused by loss of native vegetation. Groups are working in rural, urban and bushland areas to assess weed problems as part of an integrated approach to sustainable land use. “Landcare groups look at the causes of weed infestation and then tackle the source of the problem as well as the weeds themselves. They remove weeds from farming areas, bushland and coastlines. Volunteers use techniques such as burning, chemical control and hand removal. It may involve changing the way that land is managed – perhaps by reducing the access of stock, people and vehicles.
Weed Spotters is a group of environmentally-concerned people who are contacted and asked to be on the lookout for potential, new and emerging weeds. Weed Spotters not only look out for weeds in the “field” but also in nurseries and garden centres, the media, email discussion groups, the internet, books etc. In Victoria in November 2004 there were over 600 Weed Spotters registered. Prospective new members in Victoria can contact Kate Blood (Kate.Blood@dpi.vic.gov.au) or write to her at DPI, PO Box 7, Beaufort, Vic 3373.
In Northern Australia two AQIS officers Barbara Waterhouse and Andrew Mitchell patrol for new plant invaders. Their beat covers an area half the size of Europe, extending across the country from Broome to Cairns and well into Papua New Guinea and Asia. To help them in their colossal task is a network of “weed spotters”, dedicated landholders and government agencies that collect unfamiliar plants they find. Working with other scientists in the CRC for Australian Weed Management and Herbaria, Waterhouse and Mitchell have shown time and again that early detection of a new invasion is the way to go – controlling, maybe even eradicating, new landscape destroyers before they can get a foothold (extract from a Weed CRC news release on the web).
The Environmental Weeds Action Network (EWAN)
This group is a community initiative to tackle the problem of environmental weeds in bushland and waterways in Western Australia. It brings together community members in both urban and rural areas, bush regenerators, local government, weed scientists and ecologists to save indigenous flora from the threat of weeds. EWAN was formed at a public meeting in February 1996 by members of community groups concerned about lack of communication between community groups and government agencies. http://members.iinet.net.au/~ewan/index.html
DPI Victoria now has a schools education program called Weed Warriors that involves children and parents in raising biological control agents in the classroom that can then be released in local weed infestations. The students learn about local weed problems and help to reduce local infestations.
Royal Botanic Gardens Melbourne
The Royal Botanic Gardens Policy for Conservation of Plant Biodiversity 30 is an organisational declaration of support for the principles of plant conservation and the preservation of biodiversity. The Royal Botanic Gardens encourages environmentally responsible horticulture and does not wish to contribute in any way to weed invasions of ecosystems.
CITES and CBD
Until recently Botanic Gardens were part of an international network exchanging seed lists – this being the main means of plant acquisition, especially of rare and unusual species. However, seed exchange is now restricted. Firstly, there is the legally binding Convention on International Trade in Endangered Species of Wild Flora and Fauna (CITES). Secondly, under the CBD there is a common agreement among many botanic gardens concerning the acquisition and use of genetic resources, including consent from the country and/or organisation of origin and potential benefit sharing (including non-monetary).
The Weed Strategic Plan
As an organisation accessing and displaying a wide range of plants, many of these being rare or unusual (it manages over 10, 000 different kinds) there is always the possibility for acquiring or displaying plants that have the potential to become environmental, agricultural, or other weeds, or to exhibit other undesirable traits.
The RBGM Weed Strategic Plan 2003-2008 (WSP) outlines ways in which the RBG can address weed problems through environmentally sound horticultural practises and, by setting an environmental “best practise” example, encourage environmentally responsible attitudes in other organisations and the general community by:
• producing lists of environmentally safe species and cultivars
• educate and inform similar organisations, the public and nursery industry about invasive garden plants that become weeds
• assemble information on and lists of weeds, especially in the local context
• monitor all existing stock as well as stock entering and leaving the RBG
• assess the threat that popular or common horticultural plants may present to related native plants in the wild (conspecifics and congeners) including the possibility of hybridization threatening wild plant populations and their genetic integrity
• ensure that plants suggested as environmentally safe “alternatives” have been given full screening
The Weed Strategic Plan can be accessed at www.rbg.vic.gov.au/horticulture/weeds.
CODES OF CONDUCT
One interesting initiative in the United States is for organisations to become signatories to a Voluntary Code of Conduct (VCC). The organisations that are signatories to the VCC include government, botanic gardens, home gardeners, landscapers and the nursery industry
In the United Kingdom a Horticultural Code of Practice called Helping to Prevent The Spread of Invasive Non-Native Species was produced by the Department of Environment, Food and Rural Affairs in March 2005 72 (available at www.defra.gov.uk). It provides advice and guidance on the safe use, control, and disposal of invasive non-native plants for everyone engaged in horticulture and related activities that involve the use of plants.
The following suggestions are adapted for Australia from the American and English Voluntary Codes of Conduct.
Suggestions for the home gardener
As already discussed the environmentally-aware home gardener and nurseryman would only grow and supply plants with low environmental or agricultural risk, being especially cautious about plants in the groups already discussed.
• Try and be aware of lists of plants that have an invasive record and to ask for non-invasive species when buying plants
• Try to develop garden designs that use non-invasive species.
• Do not swap or give away plants you know to be invasive
• Help alert other members of your local community, societies, garden clubs, family and friends about the risks posed by weeds and encourage speakers to keep groups up-to-date
• Be aware of inadvertent promotion of invasive plants through the media and assist the media to avoid future such promotions.
• Avoid transporting known invasive plants.
• Dispose of plants known to have any weedy tendencies in a responsible way.
• Seek information on the most environmentally-friendly and effective way of controlling weeds.
• Seek information about invasive plants in your area: this may be through the local council, botanical gardens, conservationists and government agencies.
• Encourage the nursery industry to label plants clearly with botanical names somewhere on the label with an indication of possible dangers to the wider environment.
• Beware of releasing aquarium weeds into waterways or drains.
• If you send seeds or cuttings abroad (whether as gifts, for science, for landscaping or for trade) check to see if the plant has the potential to become invasive.
• Avoid dumping garden waste in the bush or over the fence.
• Be aware of potential seed spread when transporting plants by covering trailers etc.
• Join volunteer community weed groups to help eliminate weeds in your area.
• Be extremely cautious in bringing in seed from overseas and be aware that this must be cleared by Biosecurity Australia.
• Participate in early warning of weeds by observing the plants that occur in your local area and be aware of the agency to be contacted with the information.
• Assist garden clubs and societies to develop weed policies
• Replace invasive plants in your garden with safe alternatives
• Seek additional information from local, State and Federal government authorities – also see www.weeds.crc.org.au
The national Weed Alert Hotline phone number 1800 084 881
Voluntary Codes of Conduct for Government
• Require risk assessment for government-led or financed plant introductions to ensure that no new harmful plant species are introduced, intentionally or unintentionally.
• Do not distribute existing holdings of invasive plant species to areas where they can potentially do harm; eliminate these holdings or maintain new or existing holdings using appropriate safeguards.
• Coordinate and facilitate collaboration in databases, early warning systems, monitoring, and other means of preventing invasive plant species problems.
• Lead and fund (subject to budgetary considerations) the development of environmentally sound methods to control harmful invasive plant species, seek control of such species on public lands and promote their control on adjacent private lands.
• Develop and promote the use of non-invasive plant species within all government units and to the public.
• Facilitate, lead, coordinate and evaluate public outreach and education on harmful invasive plant species.
• Encourage that employees and management participate in ongoing training programs on invasive plant species.
• Foster international cooperation to minimize the risk of the import and export of potentially invasive plant species.
• Develop partnerships and incentive programs to lessen the impact of invasive plant species and provide non-invasive restoration materials.
• Provide a forum for regular evaluation of the effectiveness of these voluntary codes of conduct towards preventing the invasive plant species problem.
• Enforce invasive plant species legislation at all levels.
Voluntary Codes of Conduct for Nursery Professionals
• Ensure that invasive potential is assessed prior to introducing and marketing plant species new to North America. Invasive potential should be assessed by the introducer or qualified experts using emerging risk assessment methods that consider plant characteristics and prior observations or experience with the plant elsewhere in the world. Additional insights may be gained through extensive monitoring on the nursery site prior to further distribution.
• Work with regional experts and stakeholders to determine which species in your region are either currently invasive or will become invasive. Identify plants that could be suitable alternatives in your region.
• Develop and promote alternative plant material through plant selection and breeding.
• Where agreement has been reached among nursery associations, government, academia and ecology and conservation organizations, phase-out existing stocks of those specific invasive species in regions where they are considered to be a threat.
• Follow all laws on importation and quarantine of plant materials across political boundaries.
• Encourage customers to use, and garden writers to promote, non-invasive plants.
Voluntary Codes of Conduct for Landscape Architects/h6>
• Seek out education and information on invasive species issues:
• Work with local plant ecologists, horticulturists, nurseries, botanic gardens, conservation organizations and others to determine what species in your region either are currently highly invasive or show aggressive potential. Investigate species under consideration that may present a threat.
• Increase interaction with other professionals and non-professionals to identify alternative plant material and other solutions to problems caused by harmful invasive plants.
• Take advantage of continuing education opportunities to learn more about invasive species issue
• Identify and specify non-invasive species that are aesthetically and horticulturally suitable alternatives to invasive species in your region.
• Eliminate specification of species that are invasive in your region.
• Be aware of potential environmental impacts beyond the designed and managed area of the landscape plan (e.g. plants may spread to adjacent natural area or cropland).
• Encourage nurseries and other suppliers to provide landscape contractors and the public with non-invasive plants.
• Collaborate with other local experts and agencies in the development and revision of local landscape ordinances. Promote inclusion of invasive species issues in these ordinances.
Code of Conduct for Botanic Gardens and Arboreta
• Conduct an institution-wide review examining all departments and activities that provide opportunities to stem the proliferation of invasive species and inform visitors. For example, review or write a collections policy that addresses this issue; examine such activities as seed sales, plant sales, book store offerings, wreath-making workshops, etc.
• Avoid introducing invasive plants by establishing an invasive plant assessment procedure. Predictive risk assessments are desirable, and should also include responsible monitoring on the garden site or through partnerships with other institutions. Institutions should be aware of both direct and indirect effects of plant introduction, such as biological interference in gene flow, disruption of pollinator relationships, etc.
• Consider removing invasive species from plant collections. If a decision is made to retain an invasive plant, ensure its control and provide strong interpretation to the public explaining the risk and its function in the garden.
• Seek to control harmful invasive species in natural areas managed by the garden and assist others in controlling them on their property, when possible.
• Promote non-invasive alternative plants or, when possible, help develop non-invasive alternatives through plant selection or breeding.
• If your institution participates in seed or plant distribution, including through Index Seminum, do not distribute known invasive plants except for bona-fide research purposes, and consider the consequences of distribution outside your biogeographic region.
Consider a statement of caution attached to species that appear to be potentially invasive but have not been fully evaluated.
• Increase public awareness about invasive plants. Inform why they are a problem, including the origin, mechanisms of harm, and need for prevention and control. Work with the local nursery and seed industries to assist the public in environmentally safe gardening and sales. Horticulture education programs, such as those at universities, should also be included in education and outreach efforts. Encourage the public to evaluate what they do in their own practices and gardens.
• Participate in developing, implementing, or supporting national, regional, or local early warning systems for immediate reporting and control. Participate also in the creation of regional lists of concern.
• Botanical gardens should try to become informed about invasiveness of their species in other biogeographic regions, and this information should be compiled and shared in a manner accessible to all.
• Become partners with other organizations in the management of harmful invasive species.
• Follow all laws on importation, exportation, quarantine, and distribution of plant materials across political boundaries, including foreign countries. Be sensitive to conventions and treaties that deal with this issue, and encourage affiliated organizations (plant societies, garden clubs, etc.) to do the same.
PART 6 – WEED ISSUES
The management of garden plants that have the potential to become agricultural and environmental weeds is particularly controversial and poses many difficult questions for gardeners.
Here are some FAQs concerning weeds, each with a brief discussion. Please note that there are no “right” answers to these questions.
Disputes about weeds (often concerning whether a plant is to be prohibited or not) seem to boil down to what constitutes an acceptable level of risk which, in turn, depends on how accurate our weed risk assessment is and how much we value the natural environment. It is also often a matter of reconciling environmental values with competing values: socio-cultural, scientific, heritage, economic, health, amenity, conservation, management etc. It does appear that the more objective the decision-making process and more complete the information used to mount a case, the greater likelihood there is of conflict resolution.
The questions posed here were initially compiled with botanic gardens in mind but the issues raised have general application.
1. Surely the only way for a botanic garden to be completely environmentally responsible would be to convert the site into an indigenous flora reserve and to not grow any exotic plants at all?
In principle this may be true. However, most of the plants in botanic gardens pose little, if any, environmental threat. Nevertheless, there is no doubt that the botanic gardens should minimise its environmental impacts and often substantial areas are devoted to the conservation of indigenous vegetation. Also Botanic gardens have an educative and scientific role and through the display of plant diversity, including exotic plants, promote a concern for plant life, biodiversity, and conservation, and a scientific approach to conservation issues.
2. Surely any plant can be given weed status?
Since all plants (other than sterile hybrids and ones that are maintained in cultivation by human propagation) reproduce effectively under appropriate conditions (otherwise they would not exist) it may be argued that they all have the potential to find areas where they will flourish. In practise many garden plants, especially hybrids and cultivars, reproduce very poorly and pose no environmental threat. A WWF/CSIRO report Jumping the garden fence46 states “the majority of plants available for sale by nurseries are not likely to become invasive in Australian ecosystems”.
3. Should botanic gardens be exempt from the conventions and regulations usually applied to weed management?
Growing plants that have a well-known weedy history sends an environmentally irresponsible message to the public.
Botanic gardens are scientific institutions that display plant diversity, often within a cultural landscape of local to national significance. Scientists and the general public are curious about plants that are poisonous or display other undesirable attributes, including those that are weeds. These plants may be needed for scientific research and therefore may be allowed “scientific, heritage, conservation or educational exemption” where the risk is not high. In cases like this the weed potential can be acknowledged through appropriate labelling and public education. Botanic gardens are also relatively intensively managed and so plants may be monitored more closely than in many other gardens. Nevertheless, “scientific exemption” cannot override environmental responsibilities and so there should be precautionary environmental management of the plants (removing seeding flower heads, growing in an enclosure to exclude vectors or root travel etc.). Such plants are best considered on a case-by-case basis.
4. Plants with berries are known to be quickly spread by birds and animals – should they be banned from the nursery industry and private gardens? Botanic gardens?
Plants that produce fleshy fruits are without doubt a high-risk category. Certainly they should be discouraged and/or carefully monitored. Whether botanic gardens should grow them is a question of whether there is a case for “scientific exemption” and whether they can be managed to prevent spread (see 3).
5. I know that Agapanthus is an environmental weed but since everyone grows it and I can buy it in almost any nursery there is no point in removing it from my garden?
A question like this is similar to saying “everyone else steals so why shouldn’t I?”
It is clearly true that one extra person growing Agapanthus is hardly likely to increase the environmental threat posed by this plant. However, if the case against these plants is sound then there is little option but to be environmentally responsible, at least dead-heading plants that may pose a threat (although spread appears to be mostly vegetative through the dumping of garden waste etc. 107). Situations like this create the opportunity to provide information to people who are sympathetic to good environmental intentions but who are unaware of weed histories or methods of management.
6. Do rare and unusual plants pose any environmental threat?
There is no reason in principle why rare plants should pose more environmental danger than any other plants. Collectors and botanic gardens enjoy the challenge of growing novelties and displaying plants that are rare in the wild or rarely cultivated. In botanic gardens especially such plants contribute to the diversity and variety of the collections. They can also be the subjects of scientific research or evaluation for their cultivation potential. There is, however, the problem that plants rare in the wild or in cultivation are difficult to assess for their weed potential because they have not been “trialled” through years of cultivation. An absence of records or performance in a few gardens is not evidence that the plant is innocuous. It is environmentally irresponsible to grow and share plants new to cultivation without a very careful weed assessment. Such plants must be passed through the Standard WRAP and their weed potential assessed according to their known biology.
The serious environmental weeds Coprosma repens, Mirror bush¸and Pinus radiata, Monterey Pine are uncommon to rare in their countries of origin (New Zealand and U.S.A. respectively), so rarity in country of origin does not necessarily imply that there is no weed potential.
7. Is it safe to grow plants with known weedy history if they are out of their natural climatic range?
Just because a plant is extremely weedy in Queesland (or wherever) surely that does not mean that it is necessarily weedy in my region?
It is often pointed out that plants that have weed potential in particular climates may be cultivated outside their natural climatic range without displaying any tendency to naturalise. For example, Lantana camara is generally cultivated safely in Victoria but is a widespread weed in the warmer climates of New South Wales and Queensland.
These cases are extremely hard to assess. A good weed risk assessment, in developing an evaluation of the weed risk involved, will take account of both the local conditions and those conditions under which the plant thrives. Transport by humans and pilfering from public gardens are all part of this risk equation (see 14).
For botanic gardens there is the question as to whether such plants should be on public display. Firstly, although very unlikely, it is possible for propagation material to be taken from plants to climates where they may proliferate (see 14); secondly, displaying such plants does not set a good example to the viewing public; thirdly, the likelihood of continuing substantial warming of Victoria’s climate means that plants currently weedy in warmer zones are likely to become progressively more weedy in southern Australia. It seems that each case must be considered individually and an attempt made to assess the seriousness of the risk posed.
8. Is it safe to grow plants with a known history of weediness provided they are away from natural areas?
It is sometimes suggested that the main danger to natural areas occurs when exotic plants are grown in areas abutting natural vegetation. The former Noxious Weeds Act in Victoria allowed noxious weeds to be grown in the Melbourne Metropolitan area – presumably at least partly because they were considered to pose little threat when not directly adjacent to native bushland.
Unfortunately, although it may be true that the threat posed is small, there is still the potential for plants to be transported (shoes, vehicles etc.), accidentally or deliberately, to areas where they will thrive. It is extremely difficult to decide how real such a threat is. Even in metropolitan Melbourne and other rural centres, there are lots of small bushland reserves and ribbons of linear reserves. These remnant areas are threatened by invasive garden plants carried by wind, water, birds and other vectors including dumped garden waste. Gardens anywhere are surrounded by remnant natural areas and agricultural areas which are all vulnerable to invasive garden plants.
9. If I were to remove all the potential weeds from my home garden it would mean removing about half the plants – are you seriously suggesting that is what I do?
Half the plants seems a high estimate. Nevertheless, if we are genuine and resolute about protecting the natural environment then this might result in a significant change to current horticultural practices, not only those relating to invasive plants. Develop a replacement program over a couple of years. Perhaps replace one or two every six months removing the most invasive and/or damaging first. See it as an opportunity to reinvigorate the garden.
10. The same species can reproduce more effectively in some conditions than others – how does this affect its weed risk assessment?
This question is rather similar to 7. Some plants appear to produce more seed as their growing conditions more closely approximate the conditions of natural populations – what might be called climatic fecundity. Ceratonia siliqua, Carob, produces few seed pods in Melbourne but in gardens closer to Mildura the seed pods become an ornamental feature, the same is true of Jacaranda mimosifolia. At other times it appears that certain variants within a species are more fertile than others and for less obvious reasons. Agapanthus seedlings are rarely sighted in the Royal Botanic Gardens Melbourne and yet there is little doubt that large populations have resulted from seed in naturalised populations on the Bellarine and Mornington Peninsulas. Is it possible that a wide variation in fecundity is part of the biology of certain plants?
11. If a plant has high heritage value but is an environmental or agricultural weed, should we preserve it? How do we resolve competing environmental, heritage and commercial values?
There are occasions when there is a conflict between environmental/economic and heritage values. An old Peppercorn tree, Schinus molle, might have great historical value but also be the source of potentially environmentally damaging seed. Should it be removed? Some important agricultural, horticultural and forestry plants are also weeds (e.g. Phalaris aquatica, a pasture grass; Pinus radiata, a timber tree; Olea europea, commercial olive). Here are competing commercial and conservation interests.
In cases like this the more objective information that is accumulated the greater likelihood of conflict resolution. Weed Risk Assessment gives an indication of degree of environmental risk (as likelihood of spread, and consequences should spread occur) and therefore suggests the level of precaution needed to minimise impact. In South Australia local government planners are recommended to reject planning approval for those olive orchards posing very high environmental risk, lower risk orchards are expected to put in place appropriate environmental precautions to avoid feral plants (Virtue).
Another example: in times of drought the turf industry is likely to suffer severely if it is tackled on water consumption (cool-season grasses) and also weediness (warm season grasses). What can be done?
In unfortunate cases like this every opportunity could be taken to alleviate the problem. Trying to use non-weedy grasses, reducing areas of turf if that is possible, trialling and introducing sterile cultivars and so on.
Many herbs and crop plants are weedy; how are we to deal with them? Both the carrot (Daucus carota) and wheat (Triticum aestivum) are quite widely naturalised in Australia. Here, although there are certainly enviromental threats, human interest would seem to demand some license – to ban the growth of wheat or carrots would be seen as particularly draconian if not “ridiculous”. It is not so clear with, say, Globe Artechoke (Cynara scolymus) and Olives (Olea europaea) because their need in horticulture seems less and their environmental threat possibly greater than that of wheat and carrots. Nevertheless, removing them from gardens would be seen as quite harsh. Perhaps in an environmentally responsible institution like a botanic garden they could be grown with signs indicating their environmental threat. There are more difficult cases like mints (Mentha), Black Mustard (Brassica nigra), the chamomiles, onions, Nasturtium, Salad Burnet and many more, all of which are quite widely naturalised in Australia. Decisions here are likely to be a compromise between the agricultural/environmental risk posed by the plant on the one hand with its food/cultural/social value on the other, taking into account such factors as how necessary the plant is in the gardens, how invasive it might be, and how great the impact if it escaped.
12. We like to cultivate exotic plants that grow well in the local area, but if they grow well then surely they also have an increased weed potential. Does that mean we should always select plants that don’t grow well?
Many garden plants do not pose a threat. Plants grown should be selected carefully and monitored for their weed potential. If they start rapidly reproducing in the garden, then chances are they may escape and invade elsewhere. If a plant shows these tendencies, it might be time to consider replacing it. Also see 2.
13. What can I do in my garden to help? Who can I talk to for more information?
In Victoria you could check that the plants do not occur on the state noxious weed list or the nursery industry “garden thugs” list, or any lists compiled by your local council. You can speak to your local council, DPI or check the web sites listed in this document. To get a feel for whether particular plants might be weedy you can check the on-line Global Weed Compendium. In the home garden, replace invasive garden plants with safer alternatives, dispose of garden waste responsibly (don’t dump it in bushland or over the back fence), use your circles of influence to tell others about the issue and what they can do to help. If you see invasive garden plants in local bushland and on roadsides etc., tell the responsible authority and ask for something to be done about it.
14. Any accessible plant in a public park or garden may be stolen. Propagation material can also be taken away to places where the plant could become a weed.
This must be taken into account as part of the weed risk assessment which, in turn,will include consideration of the potential impacts should the plant escape to become weedy.
15. Humans are part of nature and therefore the spread of alien plants across the globe as a result of human activity is part of a natural process. The concern with weeds is a form of xenophobia and an irrational and emotive attempt to keep the world in a pristine condition.
This booklet has outlined the economic, environmental and social reasons why invasive plants are detrimental to humans and other organisms. Tackling these issues is sound management for the future.
Biological invasions (like extinctions) are natural events but it is the rate and numbers, as well as the large distances and agency, that separates human-driven invasions from colonizations by other agencies.
PART 7 – INFORMATION RESOURCES
RESOURCE GUIDE AND CONTACT DIRECTORY
(AUSTRALIA AND NEW ZEALAND)
Blood, K., Taylor, U., Nugent, T. & Timmins, S. (1998). Weed Navigator. Weeds CRC, Adelaide.
Blood, K. (2003). Weed identification, recognition of key environmental weeds, and where to find information resources. In Proceedings, First Biennial Conference, Developments in Weed Management, 20-21 August 2003, held at All Seasons International Hotel, Bendigo. (Weed Society of Victoria Inc.: Frankston, Victoria) pp. 16.
• Under Control , Pest Plant and Animal Management News. Victorian Department of Primary Industry.
• Plant Protection Quarterly. R.G. & F.J. Richardson, Meredith, Vic.
• Weedscene. Newsletter of the Weed Society of Victoria Inc.
• Weedwatch. Newsletter of the Cooperative Research Centre for Australian Weed Management. Available on-line at www.weeds.crc.org.au/documents/weed_watch_
Centre for Biological Information Technology (2004). Declared plants of Australia: an identification and information system.
An interactive identification tool for declared plants of Australia using Lucid software. $80.
see also www.cbit.uq.edu.au/software/declaredplants/default.htm
Web site of Biosecurity Australia plant section. For policies, reviews, import restrictions etc.
Site of the Council of Heads of Australian Botanic Gardens. A combined inventory of plants in the 6 major Australian
botanic gardens, as at 1992, can be accessed here.
CODES OF CONDUCT
A Horticultural Code of Practice called “Helping to prevent the spread of invasive non-native species” published by the
UK Department for Environment, Food and Rural Affairs in March 2005.
Excellent American site with invasive plant Codes of Conduct for government, botanic gardens, home gardeners, landscapers and the nursery industry
New South Wales plantnet.rbgsyd.nsw.gov.au/
North America www.fna.org/FNA/volumes.shtml
Western Australia florabase.calm.wa.gov.au/
Australian Federal Department of Environment and Heritage. An important account of weeds in Australia. includes: description, control methods including biological control; National Weeds Strategy; weeds of national significance; weeds on the national environmental alert list; Australian government funding; Natural Heritage Trust; links; publications.
Presents literature on weed identification, weed management and control, and environmental and agricultural weeds.
A weed management manual prepared as a training aid for private landholders, conservation groups, catchment management groups, local, state and territory governments and industry. Mostly environmental weeds. Many publications are available from the Australian Weed Management CRC site http://www.weeds.crc.org.au/publications/index.html
An excellent Victorian site with links to major legislation, discussion of individual weeds, important literature etc.
conferences and workshops focusing on alien plant invasions which have been held worldwide since 1992. Topics of discussion have included: the nature of invasions, the impact of alien plants on the biodiversity of native communities, available control and management options, and specific case studies of ecological traits
Federal Noxious Weed Disseminules of the U.S. Julia Scher
Released in 2005 an identification key to the 96 taxa on the USA federal noxious weed list, and 10 taxa regulated under the Federal Seed Act. Good pics, facts sheets.
International Phytosanitary Portal – the official web site for the International Plant Protection Convention
Discussion paper re quarantine policy as it relates to the WTO environment
Australian Quarantine and Inspection Service (Biosecurity). ICON is AQIS’s import conditions database. It contains the Australian import conditions for more than 18,000 foreign plant, animal, mineral and human products and incorporates prohibited weeds.
Commonwealth alert list of 28 environmental weeds
Provides a list of the currently declared noxious weeds in Victoria as in Landcare Notes (1998). Declared Noxious Weeds. KTRI ISSN 1329-833X
The Victorian DPI site describing and listing weeds in Victoria.
Provides an on-line database of all noxious weeds in Australia. These can be listed on a state
A searchable database of the noxious weed lists for all U.S. states and six southern provinces of Canada.
The United States Natural Resources Conservation Service. Includes: Federal Noxious Weed List ; State Noxious Weed Reports; State and Federal Composite List of All U.S. Noxious Weeds; Invasive Plants of the U.S. ; Introduced Plants of the U.S.
Australia’s Virtual Herbarium for records of plants in Australian Herbaria and their natural distributions.
The IUCN-ISSG’s Global Invasive Species Database
The INVADERS Database is a comprehensive database of exotic plant names and weed distribution records for five states in the northwestern United States.
American listing of international databases of weedy plants
First edition of publication below produced in 2007. Hussey, B.M.J., Keighery, G.J., Dodd, J., Lloyd, S.G. and Cousens, R.D. (2007). Western Weeds, A guide to the weeds of Western Australia. 2nd Edition. The Weeds Society of WA Inc.
The Australian Network for Plant Conservation
A new site emanating from the Eden project in the UK with information on plant conservation in horticulture.
The New Zealand Plant Conservation Network. Includes weed list and pictures of most of the New Zealand flora.
This is a 157 page pdf file of the Quarantine Proclamation under the 1908 Quarantine Act and amended 11 Mar 2005.
Page 86 has a list of plants that are quarantinable pests. Schedule 5 is a list of permitted seeds.
STRATEGIES, POLICIES, GOVERNMENT DEPARTMENTS ETC.
This is the site of the Golobal Invasive Species Programme including a downloadable summary document outlining a global perspective of invasive alien species.
Weeds Australia and National Weeds Strategy. A site managed by the National Weeds Strategy Executive to promote access to key weed policies, regulations, current issues, national initiatives, research, extension, training and personnel.
Portal to the Australian Quarantine and Inspection Service. The site explains the functions and operations of this government service.
Australian Weed Management CRC
Council of Australian Weed Societies. Links, conferences and publications.
Weeds of National Significance.
This is the web site for local government and includes their latest 2003 report on weed management. Search on “weeds”.
National Weeds Strategy Executive Committee site with useful Guidelines for Developing Weed Strategies
A report examining the State and Territory legal controls on nationally important weeds, namely the Alert List of Environmental Weeds, weeds recommended or national eradication, the Northern Australia Quarantine Strategy target plant list, and Weeds of National Significance.
The American invasive species program
Schedule 5, Permitted Seeds as at 25-5-2005
New Zealand’s National Pest Plant Accord. Procedure for monitoring plants available in commerce in New Zealand.
WEED RISK ASSESSMENT
Weeds on the Australian National Environmental Alert list.
Possibly the most comprehensive and erudite account of environmental weeds in Australia.
The INVADERS Database is a comprehensive database of exotic plant names and weed distribution records for five states in the northwestern United States.
Naturalised plants in New Zealand.
This website provides information available in the book A Global Compendium of Weeds by Rod Randall. It lists about 20,000 taxa of plants giving information about the “weedy” characteristics of each based on information from nearly 300 references.
National Plant Germplasm System, maintained by the U.S. Dept. of Ag., good for taxonomic information including economic importance, distributional range, references and other databases with information.
Missouri Botanical Garden’s VAST (VAScular Tropicos) nomenclatural database good for publication references and location records. The location data can be used as input to CLIMATE for determining the potential for a species to occur in Australia.
U.S Department of Agriculture Plants Database. A list of vascular plants, mosses, lichens, etc. of the U.S. and its territories. It has useful links to other sources of information on individual species.
Flora of Australia Online. The number of families available online is currently limited.
EMAIL AND DISCUSSION GROUPS, POLITICAL ACTION
Australia-wide weed discussion group.
People concerned that Australia is not responding adequately to invasive species formed the Invasive Species Council to lobby against invasive species of all kinds. The ISC became incorporated in July 2002, and held its first public event on 26 August 2002 in Melbourne. It has an informative newsletter, the Feral Herald.
WEED SOCIETIES AND GROUPS
Mountain Invasion Research Network.
Weed Society of Victoria. Other weed societies include The Weed Society of New South Wales (Inc), The Weed Society of Queensland (Inc), The Weed Management Society of South Australia, The Weed Society of Western Australia (Inc) and the Tasmanian Weed Society (Inc). The umbrella organisation is the Council of Australian Weed Societies (CAWSS).
Global Invasive Species Information Network
The Center for Invasive Plant Management
Environmental Weeds Action Group. Community based network in WA
MAJOR ORGANISATIONS INVOLVED IN WEED MANAGEMENT IN VICTORIA
National Herbarium of Victoria
Plant identification as part of the Weed Alert Rapid Response project.
Australian Research Centre for Urban Ecology (ARCUE)
A division of RBG ARCUE researches all aspects of urban ecology.
Department of Sustainability and Environment (DSE)
Responsible for the management of crown land that is not national park.
Department of Primary Industry (DPI)
DPI conducts weed management in Victoria. [
Municipal Association of Victoria (MAV)
This is the umbrella organisation for local government.