Plant Protection Quarterly Vol.25(2) 2010 75 by the Steering Group for inclusion on the NPPA list. Risk assessment for the New Zealand National Pest The Steering Group is made up of rep- resentatives from MAF Biosecurity New Plant Accord: which species should be banned from Zealand, the Department of Conserva- tion, Regional Councils and the Nursery sale? and Garden Industry Association. This group determines the fi nal list of NPPA A B M.J. Newfi eld and P.D. Champion plants based on recommendations of the A Biosecurity New Zealand, Ministry of Agriculture and Forestry, PO Box TAG and factors related to costs of imple- 2526, Wellington, New Zealand. menting the NPPA (for example the value B National Institute of Water and Atmospheric Research (NIWA), PO Box of that plant to the horticultural trade or 11-115, Hamilton, New Zealand. other groups). The TAG assessment process Criteria for the TAG There are hundreds of invasive or poten- Summary tially invasive plants in New Zealand, but The National Pest Plant Accord (NPPA) contained approximately 110 species that it is neither desirable nor feasible to in- is an approach used in New Zealand to were banned from sale (MAF 2000). This clude every one on the Accord list. The manage the problem of invasive plants list was managed through local govern- original NPPA list contained 92 taxa, and that are in the horticultural trade. It is a ment and there was some regional varia- an additional 108 taxa were nominated by cooperative agreement between central tion in the species included. members of the Consultative List. Typi- government agencies, local government Since 2001, the New Zealand approach cally, species are nominated and assessed, agencies and the Nursery and Garden to the management of invasive plants in but in some cases subspecies, varieties Industry Association. Species included horticulture has been a cooperative agree- or cultivars may be assessed separately. in the Accord list are legally prohibited ment between central government, local Some of the nominations were for whole from sale, propagation and distribution government and industry. The agreement genera, but in these cases individual spe- under provision of the Biosecurity Act is known as the National Pest Plant Ac- cies within the genus were assessed. The 1993. There are hundreds of invasive or cord (NPPA). The main focus of the NPPA TAG therefore had 200 taxa to assess and potentially invasive plants in New Zea- is education and awareness, but plants in- prioritize, within a limited timeframe and land, but it is neither desirable nor fea- cluded on the NPPA list are also prohib- budget. sible to include every invasive plant on ited from sale, propagation and distribu- The assessment criteria for the TAG are the Accord list. tion throughout New Zealand under the outlined in Champion (2005). There are A robust and transparent weed risk as- Biosecurity Act (1993). three main factors that determine whether sessment process is required to support The purpose of NPPA is to prevent sale, a particular taxon will be included on the decision-making and prioritization for propagation and distribution of invasive NPPA: which taxa to include on the Accord list. plants in the horticultural trade, includ- • The impact or potential impact of the Criteria for inclusion in the Accord list ing the less formal part of the trade such plant. were developed and assessments were as markets and fairs. Inclusion of a taxon • The effectiveness of the NPPA as a conducted by members of a Technical on the NPPA list does not impose obliga- management tool for that taxon. Advisory Group (TAG). Approximately tions on landholders or agencies to man- • The cost of including that taxon on the 200 taxa were assessed and prioritized by age that taxon; this type of management NPPA list (whether or not that taxon is the TAG in 2005. No current weed risk is addressed through Regional Pest Man- valued for various purposes and what assessment tool was available to deter- agement Strategies administered by Re- the cost would be to the horticultural mine taxa for the NPPA list, although gional Councils or other local government trade or other groups if it was included some existing systems were used to pro- agencies who have responsibility for pest on the NPPA list). vide additional information. The crite- management. It is the role of the TAG to assess the fi rst ria and process used are described, and two factors (the third being the role of the future directions and improvements are The NPPA process Steering Group). The TAG process is out- discussed. The selection of taxa for the 2006 review lined here. Keywords: Invasive plants, horticul- of the NPPA list was managed through The fi rst stage of the assessment is effec- ture, weed risk assessment. three key groups, the Consultative List, tively a weed risk assessment, considering the Technical Advisory Group and the factors such as invasiveness in New Zea- Introduction Steering Group. land and overseas, presence of undesir- The use of invasive plants in horticulture The Consultative List includes staff of able traits, ability to spread, competitive is a well-recognized and often contentious central and local government agencies, ability, impact on values (such as primary issue (see for example Reichard and White members of the horticultural industry and production or the function of natural eco- 2001). New Zealand has taken a number of the wider public. Member of this group systems) and resistance to management. approaches to limiting the spread of inva- can nominate potential NPPA plants and This fi rst stage addresses the criteria un- sive plants through horticulture. The fi rst comment on the assessments that have der the Biosecurity Act (1993) for deter- was in 1983 when the sale of six aquari- been done on those taxa before a fi nal de- mination of an Unwanted Organism1, um species was banned under the Nox- cision is made. ious Plants Act (1978) (Champion 2005). The Technical Advisory Group (TAG) 1 Unwanted Organism means any organ- In 1993 a voluntary agreement called the is made up of scientists with a range of ism that a Chief Technical Offi cer believes Forest Friendly Award scheme included expertise relevant to assessing taxa for in- is capable or potentially capable of causing 23–28 terrestrial species (Craw 1994). The clusion on the NPPA list. This group rec- unwanted harm to any natural or physical next approach used was the National Sur- ommends which of the taxa nominated by resource or human health (Biosecurity Act veillance Pest Plant List in 1996, which the Consultative List should be considered 1993). 76 Plant Protection Quarterly Vol.25(2) 2010 because if it doesn’t meet these criteria, inclusion on the NPPA list because of their expected that all the current NPPA taxa there is no legal basis for including it on potential as weeds. will need to be reassessed. the NPPA list. Individual TAG members assigned Two particular areas have been identi- If a taxon is considered to have a sub- their allocated taxa to one (or occasionally fi ed for improvement for the next round of stantial impact as a weed in New Zealand, more) of six categories based on the crite- the NPPA. The fi rst is how to better incor- or it is considered likely to have a sub- ria in Champion (2005) (see Table 1). The porate an assessment of current and po- stantial impact in the future, then the sec- completed assessments were then sent to tential distribution into the NPPA assess- ond question is whether the NPPA is the all other TAG members for comment. ment process. While there are tools and correct tool for managing that taxon. This Following the initial assessment and approaches for assessing potential distri- factor considers appeal as a cultivated comments, the TAG met to discuss taxa bution (for example CLIMEX, Sutherst plant, the difference between current and classifi ed as uncertain and those where et al. 2007), the time and resources were potential distribution in New Zealand, the opinions differed. Following the discus- not available to use these tools within the current control approaches and the man- sions, taxa were allocated to fi ve catego- NPPA assessment process. For some taxa agement status. ries (see Table 2). These were the TAG’s the available information was so limited recommendations to the Steering Group. that even if the time and resources were Available weed risk assessment systems available, it may have been diffi cult to fi nd For decision makers, a system that gave a Final NPPA list the information required to use models score to enable prioritizing was desirable. The 2006 NPPA list contained 109 taxa at such as CLIMEX. The second area was as- There are a number of existing weed risk species level or below, and four genera. sessing taxa where there is some evidence assessment tools available in New Zea- In four cases, hybrids of NPPA taxa were that certain cultivars are less invasive than land and these were considered for use in also included, but hybrids of NPPA taxa the wild type of the species. Under the Bi- the NPPA assessment process. are normally not considered to be includ- osecurity Act (1993) all subspecies and cul- The weed risk assessment model of ed on the NPPA. Three more taxa were tivars are included when a species is listed Williams (1996) is based on the Australian added in 2007 and seven more in Septem- on the NPPA, unless specifi cally excluded. weed risk assessment model (Pheloung ber 2008. The delay in listing some taxa Apparently sterile cultivars are sometimes 1995). The model was developed to screen was to allow phase-out of stock by nurser- excluded from the NPPA on the rationale new plant imports and does not consider ies. Some high and medium priority taxa that they are not invasive. There are no the management benefit from control- recommended for inclusion by the TAG criteria to evaluate cultivar weed potential ling a particular taxon using a particular were not included because although they compared to the parent species but suita- management strategy. Three assessment met the fi rst two criteria they did not meet ble criteria are currently being developed. systems were designed specifi cally for as- the Steering Group’s criteria for costs re- sessing weeds based on their impact on lating to their inclusion. Many low prior- Acknowledgments conservation values (Owen 1997, Williams ity taxa were not included. The fi nal list is We would like to thank the other mem- et al. 2002, Williams and Newfi eld 2002, given in Appendix 1. bers of the Technical Advisory Group who Williams et al. 2004). Because the NPPA in- took part in the assessments in 2005 (Grae- cludes all weeds that may be transported Where to from here? me Bourdôt, Peter Heenan, Ian Popay, Shi- through the horticultural trade, including The NPPA specifi es that the list will be roma Sathyapala, Kathryn Whaley, Peter those that affect primary production or reviewed every fi ve years, so the next Williams) and John Randall and Peter Wil- human health, the systems developed for review is scheduled for 2011. It is not liams for reviewing the manuscript. conservation use were not suitable. The model developed by Champion and Clay- ton (2000) is used for assessing aquatic Table 1. Categories to which assessed taxa were assigned by TAG members weeds and is therefore not relevant for at the fi rst stage of the NPPA assessment process. terrestrial plants. None of the available risk assessment Category Number of taxa or prioritization tools was designed to an- Include on NPPA as high priority 83 swer the specifi c questions required for Include on NPPA as medium priority 48 the NPPA and none would give a score 22 that represented the management benefi t Include on NPPA as low priority of including a taxon on the NPPA list. Uncertain needs discussion 11 Uncertain needs more information 5 Assessment and prioritization 21 A process was developed that would Don’t include on NPPA use the experience of the TAG members, Not assigned to one of the above categories 10 information from the various weed risk Total 200 assessment tools and peer review of as- sessments within the TAG. Each of eight TAG members was allocated taxa within their area of expertise to assess against a Table 2. Categories to which assessed taxa were assigned by the TAG at the series of questions based on the criteria end of the NPPA assessment process. in Champion (2005). Scores for the weed Category Number of taxa risk assessment model (Williams 1996) and where relevant the aquatic weed risk Include on NPPA as high priority 82 assessment model (Champion and Clay- Include on NPPA as medium priority 51 ton 2000) were available for most taxa and Include on NPPA as low priority 28 were included as supporting information. No but reassess next round 11 These scores were particularly relevant No 28 to taxa which have not yet become a sig- nifi cant problem but were nominated for Total 200 Plant Protection Quarterly Vol.25(2) 2010 77 References Appendix. List of taxa on the NPPA list, September 2008. Champion, P.D. (2005). Evaluation criteria Scientifi c name Common name for assessment of candidate species for inclusion in the National Pest Plant Ac- Acmena smithii monkey apple cord. Report to Biosecurity New Zea- Ailanthus altissima tree of heaven land. NIWA Client Report: HAM2005- Akebia quinata akebia 027. Alternanthera philoxeroides alligator weed Champion, P.D. and Clayton, J.S. (2000). Anredera cordifolia Madeira vine ‘Border control for potential aquatic Araujia sericifera moth plant weeds. Stage 1. Weed risk model’. Sci- Aristea ecklonii aristea ence for Conservation 141. (Depart- Arundo donax giant reed ment of Conservation, Wellington). Asparagus asparagoides smilax Craw, J. (1994). Keeping our gardens for- est friendly. Forest and Bird Magazine Asparagus densifl orus (excluding cultivar Meyeri/Myersii) bushy asparagus 271, 8-12. Asparagus scandens climbing asparagus MAF (2006). The National Pest Plant Ac- Berberis darwinii Darwin’s barberry cord. http://www.biosecurity.govt. Bomarea caldasii bomarea nz/pests/surv-mgmt/mgmt/prog/ Bomarea multifl ora bomarea nppa; accessed 29 Feb 2008. Bryonia cretica white bryony Owen, S.-J. (1997). Ecological weeds on Calluna vulgaris (excluding double-fl owered cultivars) heather conservation land in New Zealand: a Cardiospermum grandifl orum balloon vine database. January 1997 Working Draft. Cardiospermum halicacabum balloon vine Department of Conservation, Welling- Carpobrotus edulis and hybrids iceplant ton. Pheloung, P.C. (1995) Determining the Celastrus orbiculatus climbing spindleberry weed potential of new plant introduc- Ceratophyllum demersum hornwort tion to Australia. Draft report to the Cestrum parqui green cestrum Australian Weeds Committee and the Chrysanthemoides monilifera boneseed Plant Industries Committee. Agricul- Clematis fl ammula clematis ture Protection Board: Western Aus- Clematis vitalba old man’s beard tralia. Cobaea scandens cathedral bells Reichard, S.H. and White, P. (2001). Hor- Cortaderia jubata purple pampas grass ticulture as a pathway of invasive plant Cortaderia selloana pampas grass introductions in the United States. Bio- science 51(2), 103-13. Cotoneaster simonsii Khasia berry Sutherst, R.W., Maywald, G.F. and Kriti- Cotyledon orbiculata African pig’s ear cos, D.J. (2007). CLIMEX Version 3: Crassula multicava fairy crassula User’s Guide. (www.Hearne.com.au). Cyathea cooperi Australian tree fern Hearne Scientific Software Pty Ltd; Dipogon lignosus mile-a-minute 2007. 131 pp. Drosera capensis Cape sundew Williams, P.A. (1996). A weed risk assess- Eccremocarpus scaber Chilean glory creeper ment model for screening plant imports Egeria densa oxygen weed into New Zealand. Landcare Research Ehrharta villosa pyp grass Contract Report: LC 9596/080. Eichhornia crassipes water hyacinth Williams, P.A., Wilton, A. and Spencer, N. (2002). A proposed conservation weed Eomecon chionantha snow poppy risk assessment system for the New Equisetum all species horsetail Zealand border. Science for Conservation Eragrostis curvula African love grass 208, 47 pp. (Department of Conserva- Erigeron karvinskianus Mexican daisy tion, Wellington). Euonymus japonicus Japanese spindle tree Williams, P.A. and Newfi eld, M. (2002). A Ficus rubiginosa Port Jackson fi g weed-risk assessment system for new Fuchsia boliviana Bolivian fuchsia conservation weeds in New Zealand. Galeobdolon luteum aluminium plant Science for Conservation 209, 23 pp. (De- Gunnera tinctoria Chilean rhubarb partment of Conservation, Wellington). Williams, P.A., Boow, J., La Cock, G. and Gymnocoronis spilanthoides Senegal tea Wilson, G. (2004). Testing the weed-risk Hedychium fl avescens yellow ginger assessment system for new conserva- Hedychium gardnerianum kahili ginger tion weeds in New Zealand. Landcare Heracleum mantegazzianum giant hogweed Research Contract Report LC0004/040, Hieracium all species hawkweed Nelson. Homalanthus populifolius Queensland poplar Homeria collina Cape tulip Houttuynia cordata chameleon plant Hydrilla verticillata hydrilla Hydrocleys nymphoides water poppy Hypericum androsaemum tutsan Ipomoea indica blue morning glory Iris pseudacorus yellow fl ag 78 Plant Protection Quarterly Vol.25(2) 2010 Jasminum humile Italian jasmine Lagarosiphon major oxygen weed Lantana camara lantana Ligustrum lucidum tree privet Lilium formosanum Formosa lily Lonicera japonica Japanese honeysuckle Ludwigia peploides subsp. montevidensis primrose willow Lythrum salicaria purple loosestrife Macfadyena unguis-cati cat’s claw creeper Menyanthes trifoliata bogbean Myoporum insulare and hybrids Tasmanian ngaio Myrica faya fi re tree Myricaria germanica false tamarisk Myriophyllum aquaticum parrot’s feather Nassella all species Nephrolepis cordifolia tuber ladder fern Nuphar lutea yellow water lily Nymphaea mexicana Mexican waterlily Nymphoides geminata marshwort Nymphoides peltata fringed water lily Ochna serrulata Mickey Mouse plant Osmunda regalis royal fern Panicum maximum Guinea grass Passifl ora caerulea blue passionfl ower Passifl ora tarminiana northern banana passionfruit Passifl ora tripartita banana passionfruit Pennisetum all species Phragmites australis phragmites Pinus contorta lodgepole pine Pistia stratiotes water lettuce Pittosporum undulatum sweet pittosporum Plectranthus ciliatus blue spur fl ower Polygala myrtifolia (excluding ‘Grandifl ora’) sweet pea shrub Potamogeton perfoliatus clasped pondweed Prunus serotina rum cherry Pyracantha angustifolia fi rethorn Reynoutria japonica and hybrids Asiatic knotweed Reynoutria sachalinensis and hybrids giant knotweed Rhamnus alaternus evergreen buckthorn Rhododendron ponticum rhododendron Sagittaria montevidensis arrowhead Sagittaria platyphylla sagittaria Sagittaria sagittifolia arrowhead Salix cinerea grey willow Salix fragilis crack willow Salvinia molesta salvinia Schinus terebinthifolius Christmas berry Schoenoplectus californicus Californian bulrush Selaginella kraussiana selaginella Solanum marginatum white-edged nightshade Solanum mauritianum woolly nightshade Tradescantia fl uminensis wandering Willie Tropaeolum speciosum Chilean fl ame creeper Tussilago farfara coltsfoot Typha latifolia great reedmace Utricularia arenaria bladderwort Utricularia gibba bladderwort Utricularia livida bladderwort Utricularia sandersonii bladderwort Vallisneria gigantea eelgrass Vallisneria spiralis eelgrass Zantedeschia ‘Green Goddess’ green goddess Zizania latifolia Manchurian wild rice