Border security: Spotlight on weeds

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Katrina L. Cuthbert

Australian Government Department of Agriculture, Fisheries and Forestry, GPO Box 858, Canberra, Australian Capital Territory 2601, Australia.

Cite this article as:

Cuthbert, K.L. (2013). Border security: Spotlight on weeds. Plant Protection Quarterly 28(3), 66-7.


Australia formally adopted the Pheloung Weed Risk Assessment (WRA) system to screen new plant introductions in 1997, following the 1996 ‘Nairn’ Review of Quarantine (Nairn et al. 1996). Since the adoption of the WRA system, roughly 3000 plants have been assessed with 47% accepted for importation into Australia, 24% prohibited due to their high weed risk and 29% requiring further evaluation. Despite the large number of WRAs resulting in an ‘accept’ result, attempts are still being made to illegally import seeds and live plant material. Millions of people, mail parcels, baggage, ships, animals, plants and cargo containers entering Australia are inspected for prohibited articles by the Australian Government Department of Agriculture, Fisheries and Forestry (DAFF) staff every year. In 2012 alone, roughly 26 000 consignments of seeds and 7 100 items of live plant material were seized. The main route of entry was through international airports in passenger baggage. The most commonly seized seeds and live plants were garden ornamentals. Indonesia was the most common country of origin for seized seeds, whilst India was the most common country of origin for seized live plant material. As quarantine risk material is not evenly distributed with arriving passengers and goods, DAFF is implementing reforms to Australia’s biosecurity system to better manage the risks of pests entering, establishing and spreading in Australia by targeting areas of highest risk.

Keywords: weed risk assessment, quarantine.


In the years following European settlement, more than 26 000 plant species have been introduced into Australia for horticultural, ornamental and/or agricultural purposes (Randall 2007). Of these, more than 2 700 have become naturalised in Australia, with the number of naturalised plants increasing by 10–30 species per year (Groves 1997). Within the naturalised flora, 429 species are declared noxious weeds under State/Territory legislation or are under some form of active control in Australia (Groves et al. 2003).

In 2004, the economic cost of weeds to Australian agriculture was estimated to be close to $4 billion per year (Sinden et al. 2004). The environmental cost is also high, with weeds second only to habitat loss as a cause of biodiversity loss (DSEWPaC 2012). Consequently, the most cost effective and technically feasible means of managing new weed incursions in Australia is preventing their initial introduction.

Quarantine in Australia

The weed risk assessment process

For well over a century, introductions of new plants into Australia went unchecked until the establishment of the Australian Government Quarantine Act 1908. Under the Act, a quarantine officer could quarantine any plant if they felt it posed an unacceptably high risk. However, the Act was primarily concerned with potential disease transmission or insect infestations and plants were not systematically assessed for weed potential until 1991. Quarantine in Australia was reviewed in 1996 (Nairn et al. 1996) resulting in Australia’s formal adoption, in 1997, of a Weed Risk Assessment (WRA) process to screen new plant introductions. The WRA process is a science-based, quarantine risk analysis tool used for determining the weed potential of new plants proposed for importation into Australia as seeds, nursery stock or tissue culture. It is a three-tiered process (Riddle et al. 2008) that utilises the Pheloung (1995) system as its second tier. The objective of the process is to pre-screen material so that non-invasive plant species can be imported, while preventing potentially invasive species from entering Australia. The assessment is conducted irrespective of the country of origin or the intended end-use. The system is transparent and meets Australia’s international obligations, including those of the World Trade Organisation Agreement on the Application of Sanitary and Phytosanitary Measures and the International Plant Protection Convention.

Since the adoption of the WRA system, over 6 000 plants proposed for importation have been processed by the Australian Government Department of Agriculture, Fisheries and Forestry (DAFF) with roughly 3 000 requiring formal assessment using the Pheloung (1995) system. Forty-seven percent of species assessed using the Pheloung (1995) system have been permitted entry into Australia due to their low risk of becoming weeds, 24% have been prohibited due to their high weed risk and 29% require further evaluation. Species may require further evaluation when there is insufficient information to conduct an assessment or when the plant has a mix of both weedy and non-weedy traits. Species requiring further evaluation are prohibited entry into Australia until additional information becomes available to allow reassessment.

Requests to import plants are received from hobbyists, gardening societies, wholesale and retail nurseries, horticultural companies, agriculture suppliers, botanical gardens, research institutes, state government departments, genetic resource centres and private enterprises. However, the vast majority of applications come from hobbyists who apply for one or two ornamental plant species only.

Implementation of quarantine policy

Despite the large number of WRAs resulting in the species being permitted entry, attempts are still being made to illegally import seed and live plant material into Australia. Every year DAFF screens, inspects and clears millions of people, baggage, mail items, ships and cargo containers entering Australia for prohibited articles. In 2011–2012, Australia received around 1.7 million sea cargo consignments, 17 million air cargo consignments, 16 million international passengers and crew, and 177 million mail items. Of these, DAFF intervened with 310 000 sea cargo consignments, 820 000 air cargo consignments, 6.9 million passengers, 52 million mail articles and conducted 21 000 vessel inspections. Approximately 330 000 items were seized at international mail centres, and from international airports and seaports around the country. Close to 28% of these items were undeclared, and 10% of all seizures consisted of seeds and/or live plant material (Table 1). The main method of entry for seed and live plant material was through international airports in passenger baggage with roughly 20 000 seed items and 5 000 items of live plant material seized.

Garden ornamentals accounted for the majority of illegal introductions of seeds and live plants. Alarmingly, escaped garden ornamentals are also the primary source of new naturalised plants in Australia and are by far the greatest source of agricultural and environmental weeds (Groves et al. 2005). In 2012, Indonesia was the most common country of origin for seized seeds, whilst India was the most common country of origin for prohibited live plant material.

In the years following the implementation of the WRA process, there have been high numbers of prohibited species being seized at the international border. For example, in 2010 live Hygrophila costata Nees (Glush weed) plants were seized at the international border. Glush weed is an invasive and noxious aquatic weed in south-eastern Queensland and has been ranked among the top 20 most invasive plant species in the region. The species’ range extends from Queensland along the coast of New South Wales to the greater Sydney region. Glush Weed occupies shallow water habitats, particularly along the perimeter of freshwater lakes and slow-moving streams. Aquatic weeds are of particular concern due to their ability to choke waterways, starving the system of light, oxygen and nutrients. Aquatic weeds also obstruct the access of livestock to water and alter the flow of water in irrigation channels, as well as compete with beneficial native plant species, causing a reduction in biodiversity and loss of habitat for animals that use the waterway. The seizure of these plants at the international border prevents the potential spread of Glush weed into new areas in Australia.

Aside from weed risk, illegally imported plants and seeds present a variety of biosecurity concerns including infestations of exotic insects, contamination with soil which may also carry pathogenic agents and plant diseases, or infection from fungi, bacteria, viruses or nematodes.

Biosecurity reform

While geographical isolation has played a key role in maintaining Australia’s freedom from some of the world’s most severe pests1, biosecurity risks are growing due to increasing passenger and trade volumes including: greater numbers of imports from higher risk sources; population growth and spread into new areas, bringing people and goods closer to agricultural production and natural ecosystems; increasingly intensive agriculture; increased globalisation; and climate change. Following the ‘Beale’ review of quarantine (Beale et al. 2008), DAFF is implementing reforms to Australia’s biosecurity system to better manage the risks of pests entering, establishing and spreading in Australia and potentially causing harm to people, the environment and the economy.

Biosecurity risk is not evenly distributed in arriving passengers and goods. Consequently, a key component of the biosecurity reforms is a change from mandatory intervention at the border to a ‘risk-based’ approach. This approach enables DAFF to direct more time and resources towards areas of higher risk to Australia’s biosecurity by freeing up resources from areas with comparatively low degrees of risk. This approach also recognises and encourages good biosecurity compliance behaviour. Other key reform themes include: managing biosecurity risk across the continuum – offshore, at the border and onshore; strengthening partnerships with stakeholders; intelligence-led and evidence-based decision making; and being supported by modern legislation, technology and business systems.

For example, processed cocoa imports have historically required 100% inspection. Following a reassessment of the risk and a review of the compliance history, it was found that no pests of quarantine concern had been detected on inspected processed cocoa. Consequently, the inspection rate was cut to 5%. In addition to the obvious cost benefits associated with reduced inspection rates, this change has enabled DAFF to direct greater resources towards analytical systems and intelligence to target illegally imported goods, such as seeds and live plants. Moreover, additional import conditions have been implemented for higher risk commodities, such as tomato seeds, which now require testing for emerging seed-borne pathogens.


Since 1908, quarantine has played a critical role in maintaining Australia’s freedom from serious pests present in other parts of the world. The WRA process in particular has proven to be highly effective at preventing the introduction of potential weeds into Australia. Current reforms to Australia’s biosecurity system will further improve quarantine procedures and provide greater protection for our agricultural industries and environment.


Beale, R., Fairbrother, J., Inglis, A. and Trebeck, D. (2008). One Biosecurity. A working partnership. The independent review of Australia’s quarantine and biosecurity arrangements. (Australian Government, Barton, Canberra)  244 pp.

DSEWPaC, Department of Sustainability, Environment, Water, Population and Communities (2012). Why are weeds a problem? Weeds in Australia. (accessed 19 March 2013).

FAO, Food and Agriculture Organisation (2012). International Standards for Phytosanitary Measures (ISPM) No. 5: Glossary of phytosanitary terms. (Secretariat of the International Plant Protection Convention, Rome). 27 pp.

Groves, R.H. (1997). ‘Recent incursions of weeds to Australia 1971–1995’. Technical Series No. 3. Cooperative Research Centre for Weed Management Systems, Adelaide). 68 pp.

Groves, R.H., Boden, R. and Lonsdale, W.M. (2005). ‘Jumping the garden fence: invasive garden plants in Australia and their environmental and agricultural impacts’. CSIRO report prepared for WWF-Australia. (World Wildlife Fund-Australia, Sydney).

Groves, R.H., Hosking, J.R., Baitianoff, G.N., Coole, D.A., Cowie, I.D., Johnson, R.W., Keighery, G.J., Lepschi, B.J., Mitchell, A.A., Moerkerk, M., Randall, R.P., Rozefelds, A.C., Walsh, N.G. and Waterhouse, B.M. (2003). Weed categories for natural and agricultural ecosystem management. (Bureau of Rural Sciences, Canberra). 194 pp.

Nairn, M.E., Allen, P.G., Inglis, A.R. and Tanner, C. (1996). ‘Australian quarantine: a shared responsibility’. (Department of Primary Industries and Energy, Canberra). 284 pp.

Pheloung, P.C. (1995). Determining the weed potential of new plant introductions to Australia. A report to the Standing Committee on Agriculture and Resource Management, Australia. 35 pp.

Randall, R.P. (2007). ‘The introduced flora of Australia and its weed status’. (Cooperative Research Centre for Australian Weed Management, Adelaide).

Riddle, B., Porritt, D. and Reading, K. (2008). Australia’s Weed Risk Assessment system and the Permitted Seeds List. Plant Protection Quarterly 23(2), 77–80.

Sinden, J., Jones, R., Hester, S., Odom, D., Kalisch, C., James, R. and Cacho, O. (2004). ‘The economic impact of weeds in Australia’. Technical Series No 8. (Cooperative Research Centre for Australian Weed Management, Adelaide,). 55 pp.

First published online: September 6, 2013