Invasive Weeds
Primary reference(s)
FAO, 2017. Glossary of phytosanitary terms. ISPM 5. International Standards for Phytosanitary Measures. Food and Agriculture Organization of the United Nations (FAO). Accessed 11 October 2020.
Additional scientific description
Invasive weeds are plants growing in agricultural lands and natural habitats where they are not wanted and where they compete with plants grown or natural resources causing significant economic or environmental damage. The term also includes any plant that can directly or indirectly injure or cause damage to crops, livestock, poultry, natural habitats or other interests of agriculture, irrigation, navigation or the natural landscapes (USDA, 2016).
In April 2001, the International Collection of Microorganisms from Plants (ICMP) recognised that under the International Plant Protection Convention’s existing mandate, to take account of environmental concerns, further clarification should include consideration of the following points relating to the potential environmental risks of pests: reduction or elimination of endangered (or threatened) native plant species; reduction or elimination of a keystone plant species (a species which plays a major role in the maintenance of an ecosystem); reduction or elimination of a plant species which is a major component of a native ecosystem; causing a change to plant biological diversity in such a way as to result in ecosystem destabilization; and resulting in control, eradication or management programmes that would be needed if a quarantine pest was introduced, and impacts of such programmes (e.g., pesticides, non-indigenous predators or parasites) on biological diversity (FAO, 2009).
The Convention on Biodiversity states that invasive plant species have been reported among inter alia seaweeds, trees, shrubs, vines, forbs and grasses. The indicative economic impacts of some invasive alien species are reported to be as follows: the impact of knapweed (Centaurea spp.) and leafy spurge (Euphorbia esula) on the economy of three US states is USD 40.5 million per year (direct costs) and USD 89 million as indirect costs (UNEP, 2001).
Metrics and numeric limits
Not available.
Key relevant UN convention / multilateral treaty
The International Plant Protection Convention (1997) is an intergovernmental treaty signed by over 180 countries, aiming to protecting the world’s plant resources from the spread and introduction of pests, and promoting safe trade (FAO, 2011). The Convention introduced International Standards for Phytosanitary Measures as its main tool to achieve its goals, making it the sole global standard setting organisation for plant health. The International Plant Protection Convention (IPPC) is one of the ‘Three Sisters’ recognised by the World Trade Organization’s (WTO) Sanitary and Phytosanitary Measures (SPS) Agreement (WTO, no date), along with the Codex Alimentarius Commission for food safety standards and the World Organization for Animal Health (OIE) for animal health standards.
The Convention on Biological Diversity (1992) has three main objectives: the conservation of biological diversity, the sustainable use of the components of biological diversity, and the fair and equitable sharing of the benefits arising out of the utilisation of genetic resources (United Nations, 1992). At the time of writing, there were 196 parties to the Convention on Biological Diversity (Secretariat of the Convention on Biological Diversity, 2013).
The Convention on Biological Diversity Decision adopted by the Conference of the Parties to the Convention on Biological Diversity (UNEP, 2018). Also recognizing the adverse impacts of invasive alien species on biological diversity and its components, especially vulnerable ecosystems, such as wetlands and mangroves, islands and Arctic regions, as well as social aspects and economic and cultural values, including those associated with indigenous peoples and local communities (UNEP, 2018).
International Health Regulations issued by the World Health Organization (WHO, 2016).
Codex Alimentarius (Codex Alimentarius, no date).
WTO Agreement on the Application of Sanitary and Phytosanitary Measures (SPS Agreement) (1994) (WTO, no date).
The relationship of the WTO with Codex, IPPC and OIE (WTO, 2007).
The UN Recommendations on the Transport of Dangerous Goods (UNECE, no date).
Examples of drivers, outcomes and risk management
Weeds are among the common plant pests affecting crop productivity significantly and being among the major factors in determining the crop production systems. Those that are parasitic or invasive can be an especially significant threat to natural resources such as forests and water resources. Poisonous weeds can also be a danger to livestock or animals in certain cases.
Weed management occurs largely through agronomic measures such as soil tillage, use of certified seeds, manure management or herbicide use. It is essential to avoid movement of contaminated seeds or other reproducible parts to facilitate effective weed management practices.
The Standards and Trade Development Facility (STDF) is a global partnership in Sanitary and Phytosanitary capacity building and technical cooperation established by the Food and Agriculture Organization of the United Nations (FAO), the World Organisation for Animal Health (OIE), the World Bank, the World Health Organization (WHO) and the World Trade Organization (WTO). Their report on International Trade and Invasive Alien Species (WTO, 2013) uses a case study to provide an important summary example of the impact of invasive weeds:
“Native to North America, common ragweed arrived in Europe in the 19th century together with cereals and possibly also clover. Large populations of this weed currently exist in some European countries, particularly in Croatia and Hungary and in parts of Austria, France, Italy and Switzerland. In other countries (notably Poland, Lithuania and Germany), it has occurred only rarely and, in general, has not survived. Common ragweed prefers open spaces and generally grows on waste grounds (e.g., along roadsides, building sites, storage areas and dumps). It is resistant to herbicides and its long seed germination capacity (over 30 years) makes control difficult. It is known to reduce yields in the cultivation of maize, wheat, sunflowers, millet, peanuts, soy, beans and potatoes. It also plays a role as a secondary host for organisms that are harmful to cultivated plants (e.g., fungal pathogens that are harmful to sunflowers). In addition to its indirect effect on plants, pollen from common ragweed can cause severe allergies in humans” (WTO, 2013:11).
Examples of Government leadership on weed management include that produced by the Canadian Ministry of Agriculture, Food and Rural Affairs (2016) and the Australian Government (no date).
The Global Invasive Species Programme (GISP) was established in 1997 to address global threats caused by invasive species and to provide support to the implementation of Article 8(h) of the Convention on Biodiversity. To increase awareness and provide policy advice, GISP has prepared a Global Strategy on Invasive Alien Species, which outlines ten strategic responses to the invasive species problem (FAO, 2017).
The Global Invasive Species Database (GISD) is a free, online searchable source of information about alien and invasive species that negatively impact biodiversity. It aims to increase public awareness about invasive species and to facilitate effective prevention and management activities by disseminating specialist knowledge and experience to a broad global audience. The GISD focuses on invasive alien species that threaten native biodiversity and natural areas, and covers all taxonomic groups from microorganisms to animals and plants (GISD, no date).
The GISD is managed by the Invasive Species Specialist Group (ISSG) of the IUCN Species Survival Commission. It was developed between 1998 and 2000 as part of the global initiative on invasive species led by the GISP (GISD, no date).
Because invasive species are addressed under different agreements and conventions (e.g., CITES, IPPC and the World Trade Organization Agreement on the Application of Sanitary and Phytosanitary Measures), many countries have difficulty in keeping up with the reporting requirements (FAO, 2017). In response, the UNEP World Conservation Monitoring Centre (UNEP-WCMC) has recently developed a set of issue-based modules summarising country obligations under the Convention on Biological Diversity and other conventions and in 2020 published a report on building a multidimensional biodiversity index (Soto-Navarro et al., 2020).
References
Australian Government, no date. Integrated weed management. Accessed 11 October 2020.
Canadian Ministry of Agriculture, Food and Rural Affairs, 2016. Weed Management. Accessed 10 October 2020.
Codex Alimentarius, no date. About Codex Alimentarius. Accessed 19 September 2020.
Earth Observing System, 2020. Weed Management: Practices for Integrated Solutions. Accessed 6 May 2021.
FAO, 2009. International Standards for Phytosanitary Measures. ISPM No. 5. Glossary Of Phytosanitary Terms. Food and Agriculture Organization of the United Nations (FAO). Accessed on 11 October 2020.
FAO, 2011. International Plant Protection Convention 1997. Food and Agriculture Organization of the United Nations (FAO). Accessed 10 October 2020.
FAO, 2017. Glossary of phytosanitary terms. ISPM 5. International Standards for Phytosanitary Measures. . Food and Agriculture Organization of the United Nations (FAO). Accessed 11 October 2020.
GISD, no date. Global Invasive Species Database (GISD). Accessed on 10 October 2020.
Secretariat of the Convention on Biological Diversity, 2013. Welcome to the CBD Secretariat. Accessed 6 May 2021.
Soto-Navarro, C.A., M. Harfoot, S.L.L. Hill, J. Campbell, H.-C. Campos Santos, F. Mora, C. Pretorius, V. Kapos, H. Allison and N.D Burgess, 2020. Building a Multidimensional Biodiversity Index – A scorecard for biodiversity health. UN Environment Programme World Conservation Monitoring Centre (UNEP-WCMC) and Luc Hoffmann Institute (LHI). Accessed 10 October 2020.
UNECE, no date. UN Recommendations on the Transport of Dangerous Goods - UN Model Regulations Model Regulations Nature, Purpose and Significance of the Recommendations. United Nations Economic Commission for Europe (UNECE). Accessed 3 October 2020.
UNEP, 2001. Invasive Alien Species: Status, impacts and trends of alien species that threaten ecosystems, habitats and species. UNEP/CBD/SBSTTA/6/INF/11. United Nations Environment Programme (UNEP). Accessed 11 October 2020.
UNEP, 2018. Decision Adopted by the Conference of the Parties to the Convention on Biological Diversity. CBD/COP/DEC/14/11. Accessed 11 October 2020.
United Nations, 1992. Convention on Biological Diversity.. Accessed 29 January 2020.
USDA, 2016. Weed risk assessment for Saccharum spontaneum L. (Poaceae) – Wild sugarcane. United States Department of Agriculture (USDA). Accessed 6 May 2021.
WHO, 2016. International Health Regulations (2005), 3rd Ed. World Health Organization (WHO). Accessed 3 October 2020.
WTO, no date. The WTO Agreement on the Application of Sanitary and Phytosanitary Measures (SPS Agreement). World Trade Organization (WTO). Accessed 3 October 2020.
WTO, 2007. The WTO and the World Organization for Animal Health (OIE) G/SPS/GEN/775. World Trade Organization (WTO). Accessed on 3 October 2020.
WTO, 2013. International Trade and Invasive Alien Species. Standards and Trade Development Facility (STDF). Accessed 11 October 2020.