Noxious weed

{{short description|Harmful or invasive weed}} [[File:Cotton Thistle, Galong, New South Wales.jpg|thumb|A mature cotton thistle, an invasive weed in Australia]] A '''noxious weed''', '''harmful weed''' or '''injurious weed''' is a weed that has been designated by an agricultural or other governing authority as a plant that is harmful to agricultural or horticultural crops, natural habitats or ecosystems, or humans or livestock. Most noxious weeds have been introduced into an ecosystem by ignorance, mismanagement, or accident. Some noxious weeds are native, though many localities define them as necessarily being non-native. Typically, they are plants that grow aggressively, multiply quickly without natural controls (such as native herbivores or soil chemistry), and cause adverse effects upon contact or ingestion. Noxious weeds are a major problem in many parts of the world, greatly affecting areas of agriculture, forest management, nature reserves, parks, and other open spaces.<ref>{{cite web|title=Cal-IPC: Invasive Plant Definitions, What Makes a Plant "Invasive"?|url=http://www.cal-ipc.org/ip/definitions/index.php|website=www.cal-ipc.org|publisher=California Invasive Plant Council|access-date=20 July 2017}}</ref>

Many noxious weeds have come to new regions and countries through contaminated shipments of feed and crop seeds, or have been intentionally introduced as ornamental plants for horticultural use.

Some "noxious weeds", such as ragwort, produce copious amounts of nectar, which is valuable for the survival of bees and other pollinators, as well as providing larval host foods and habitats. In the US, wild parsnip ''Pastinaca sativa'', for instance, provides large, tubular stems that some bee species hibernate in, larval food for two different swallowtail butterflies, and other benefits.<ref>{{cite web |url=http://www.illinoiswildflowers.info/weeds/plants/wild_parsnip.htm |title=Wild Parsnip |publisher=Illinois Wildflowers.info |access-date=13 November 2017}}</ref>

==Types== [[File:CaulerpaTaxifolia.jpg|thumb|The alga ''Caulerpa taxifolia'' is a noxious marine weed nicknamed killer algae. This is a picture of it invading a native plant bed.]] [[File:Striga gesnerioides - Purple Witchweed (5039468678).jpg|thumb|This is a parasitic noxious weed, Striga gesnerioides, commonly called Witchweed.]] [[File:Drymaria arenarioides 90650942.jpg|thumb|This is a terrestrial noxious weed, Drymaria arenarioides commonly called Lightning weed. It is sometimes confused with daisies.]] Some noxious weeds are harmful or poisonous to humans, domesticated grazing animals, and wildlife. Open fields and grazing pastures with disturbed soils and open sunlight are often more susceptible. Protecting grazing animals from toxic weeds in their primary feeding areas is therefore important.<ref name="Prather 27 etc">Prather pp. 27,45,53,67-73</ref> There are marine, terrestrial, and parasitic noxious weeds.<ref>{{Cite web |last=USDA |date=December 10, 2010 |title=Federal Noxious Weed List |url=https://www.aphis.usda.gov/sites/default/files/weedlist.pdf |access-date=April 25, 2024}}</ref>

==Control== {{main|Weed control}} Some guidelines to prevent the spread of noxious weeds are: # Avoid driving through noxious weed-infested areas. # Avoid transporting or planting seeds and plants that one cannot identify. # For noxious weeds in flower or with seeds on plants, pulling 'gently' out and placing them in a secure, closable bag is recommended. Disposal, such as hot composting or contained burning, is done when safe and practical for the specific plant. Burning poison ivy can be fatal to humans.<ref name="Wisconsin University Extension Service">{{cite web | url = http://spooner.ars.wisc.edu/wp-content/uploads/sites/67/2014/09/poisonivy1.pdf | archive-url = https://web.archive.org/web/20150622080857/http://spooner.ars.wisc.edu/wp-content/uploads/sites/67/2014/09/poisonivy1.pdf | title=Poison Ivy Identification and Control | access-date = 2015-06-22 | archive-date = 2015-06-22 | url-status = live}}</ref> # Using only certified weed-free seeds for crops or gardens.<ref name="ISDA">{{cite web | year=2005 | url=http://www.agri.idaho.gov/Categories/PlantsInsects/NoxiousWeeds/FAQs.php | title=Idaho State Department of Agriculture | access-date=2 November 2008 | archive-url=https://web.archive.org/web/20080719043111/http://www.agri.idaho.gov/Categories/PlantsInsects/NoxiousWeeds/FAQs.php | archive-date=19 July 2008 }}</ref>

Maintaining control of noxious weeds is important for the health of habitats, livestock, wildlife, native plants, and humans of all ages. How to control noxious weeds depends on the surrounding environment and habitats, the weed species, the availability of equipment, labor, supplies, and financial resources. Laws often require that noxious weed control funding from governmental agencies be used for eradication, invasion prevention, or native habitat and plant community restoration projects.<ref name="ISDA" />

Insects and fungi have long been used as biological controls of some noxious weeds and more recently nematodes have also been used.<ref name="Rao2000">{{cite book|author=V S Rao|title=Principles of Weed Science, Second Edition|url=https://books.google.com/books?id=iuNS1Yj09XYC&pg=PA319|date=2 January 2000|publisher=Taylor & Francis|isbn=978-1-57808-069-4|pages=319–}}</ref>

== Eradication == According to control experts, there are chemical, physical, and environmental ways of eradicating noxious weeds. Those include pulling the entire weed out of the ground,<ref name=":0">{{Cite web |last=Fisheries |first=Agriculture and |date=2011-06-24 |title=Physical control methods |url=https://www.business.qld.gov.au/industries/farms-fishing-forestry/agriculture/biosecurity/plants/invasive/manage/control/physical |access-date=2024-05-07 |website=www.business.qld.gov.au |language=en-AU}}</ref> spraying herbicide if it's a large area,<ref>{{Cite web |last=Department of Jobs |first=Precincts and Regions |date=2020-06-19 |title=Prescribed measures for the control of noxious weeds - Agriculture |url=https://agriculture.vic.gov.au/biosecurity/weeds/prescribed-measures-for-the-control-of-noxious-weeds |access-date=2024-05-07 |website=Agriculture Victoria |language=en-AU}}</ref> and using machines to turn over the soil.<ref name=":0" /> According to farmers, using goats can prove a more ecological way of getting rid of noxious weeds, instead of using herbicides.<ref>{{Cite news |date=2021-02-10 |title=No kidding! Goats are proving fine at controlling noxious weeds |url=https://www.abc.net.au/news/2021-02-11/ditch-herbicides-to-use-goats-to-eradicate-noxious-weeds/13139850 |access-date=2024-05-07 |work=ABC News |language=en-AU}}</ref><ref>{{Cite web |last=Lewis |first=Becca |date=2024-01-31 |title=You Can Actually Rent Goats to Eat Weeds in Your Yard |url=https://lifehacker.com/home/you-can-rent-goats-to-eat-your-weeds |access-date=2024-05-07 |website=Lifehacker |language=en}}</ref> Also, overplanting a native species is a long-term solution in eradicating noxious weeds.<ref name=":0"/>

==Controversy and biases==

Agricultural needs, desires, and concerns do not always mesh with those of other areas, such as pollinator nectar provision.<ref name=Pollinators>{{cite web |title=Which flowers are the best source of nectar? |publisher=Conservation Grade |url=http://www.conservationgrade.org/2014/10/which_flowers_best_source_nectar/ |access-date=2017-10-18 |date=2014-10-15 |archive-date=2019-12-14 |archive-url=https://web.archive.org/web/20191214024659/http://www.conservationgrade.org/2014/10/which_flowers_best_source_nectar/ }}</ref> Ragwort, for instance, was rated as the top flower meadow nectar source in a UK study, and in the top ten in another. Its early blooming period is also particularly helpful in establishing bumblebee colonies.<ref>{{cite journal|last1=Hicks|first1=DM|last2=Ouvrard|first2=P|last3=Baldock|first3=KCR|title=Food for Pollinators: Quantifying the Nectar and Pollen Resources of Urban Flower Meadows|journal=PLOS ONE |volume=11 |issue=6|date=2016|doi=10.1371/journal.pone.0158117|bibcode=2016PLoSO..1158117H|pmc=4920406|pmid=27341588|article-number=e0158117|doi-access=free}}</ref> Thistles that are considered noxious weeds in the US and elsewhere, such as ''Cirsium arvense'' and ''Cirsium vulgare'', have also rated at or near the top of the charts in multiple UK studies for nectar production, one of its native locations. These thistles also serve as a larval host plant for the painted lady butterfly. There can, therefore, be a conflict between agricultural policy and the point of view of conservationists or other groups.{{Citation needed|date=April 2021}}

==By country== {{Globalize|section|Anglophone|2name=the English-speaking world|date=February 2013}}

===Australia=== {{See also|Invasive species in Australia}}

In Australia, the term "noxious weed" is used by state and territorial governments.<ref>{{cite web|url=http://www.environment.gov.au/biodiversity/invasive/weeds/weeds/lists/index.html|title=National weeds lists|date=14 August 2012|publisher=Department of Sustainability, Environment, Water, Population and Communities|access-date=25 August 2012}}</ref>{{Example needed|date=June 2019}} thumb|Mat of alligator weeds. Some noxious weeds in Australia are alligator weeds, horsetails, and branched broomrape.<ref name=":3">{{Cite web |last=Department of Jobs |first=Precincts and Regions |date=2021-03-02 |title=State prohibited weeds - Agriculture |url=https://agriculture.vic.gov.au/biosecurity/weeds/state-prohibited-weeds |access-date=2024-05-08 |website=Agriculture Victoria |language=en-AU}}</ref> The government of Victoria will get rid of all these plants for free. Alligator weeds are banned in all the states and territories of Australia.<ref name=":3" /> They can create large mats that can cause considerable blockages of waterways.<ref name=":3" /> Horsetails are poisonous to livestock. They are also extremely challenging to eradicate, as they can fragment and the fragments can grow new plants, much like succulents.<ref name=":3" /> Branched broomrapes are parasitic noxious weeds.<ref name=":3" /> They attach themselves to the roots of other plants and extract water and nutrients.<ref name=":3" />

===Canada=== In Canada, constitutional responsibility for the regulation of agriculture and the environment is shared between the federal and provincial governments. The federal government through the Canadian Food Inspection Agency (CFIA) regulates invasive plants under the authority of the ''Plant Protection Act'', the ''Seeds Act'' and statutory regulations. The CFIA has designated certain plant species as noxious weeds in the ''Weed Seeds Order''.<ref>{{cite web|url= http://www.inspection.gc.ca/plants/plant-protection/invasive-plants/policy/eng/1328298038970/1328298211382|title= Invasive Plants Policy |date=2012-02-20 |publisher= Canadian Food Inspection Agency | access-date=31 December 2013}}</ref>

Each province also produces its own list of prohibited weeds. In Alberta, for example, a new ''Weed Control Act'' was proclaimed in 2010 with two weed designations: "prohibited noxious" (46 species) which are banned across Alberta, and "noxious" (29 species) which can be restricted at the discretion of local authorities.<ref>{{cite web|url= https://open.alberta.ca/dataset/8bb61884-bbfb-4640-bd5d-96f6e633d4ee/resource/275f7dbe-8116-4d81-ba95-329df950be7e/download/6740590-2013-alberta-invasive-plant-identification-guide-2013-06-13.pdf|title= Alberta Invasive Plant Identification Guide|year= 2013|publisher=Wheatland County|access-date=25 July 2020}}</ref>

===European Union=== {{See also|List of invasive alien species of Union concern}}

Since 2016, following the EU Regulation 1143/2014<ref>{{CELEX|32014R1143|text=Regulation (EU) No 1143/2014 of the European Parliament and of the Council of 22 October 2014 on the prevention and management of the introduction and spread of invasive alien species}}</ref> on Invasive Alien Species (IAS), the European Commission publishes updated lists of IAS of Union concern. Since 2022 August 2 there are 41 plant species of Union concern.<ref>{{cite web|url=https://environment.ec.europa.eu/topics/nature-and-biodiversity/invasive-alien-species_en|title=Invasive alien species |date=29 July 2025 }} Preventing and minimising the effects of invasive alien species on Europe's biodiversity.</ref>

thumb|Giant hogweed

An example of highly invasive and phototoxic weeds are 3 related species of hogweed: * Giant hogweed grows up to 5m tall. It has spread mostly across British Isles, Benelux, Germany, Czechia, Slovakia, Denmark, and also in some other parts of western and central Europe and Scandinavia. * Sosnowsky's hogweed grows up to 5m tall. It has spread mostly in Poland, the Baltic states, and east of the EU border, and also in some parts of central Europe, as far as Germany and Denmark. * Persian hogweed grows up to 2.5m tall. It is prevalent mostly in Scandinavia. Active measures are being taken to stop their spread and possibly eradicate them from the European environment. The European Union funded the ''Giant Alien'' project to combat hogweed.<ref>{{cite web |title=Giant Alien |url=https://www.giant-alien.dk/ |archive-url=https://web.archive.org/web/20161003024552/https://www.giant-alien.dk/ |archive-date=3 October 2016 |institution=Giant Alien Project, project no. EVK2-CT-2001-00128, European Union}}</ref><ref>{{cite web |title=Giant alien — Result In Brief |url=https://cordis.europa.eu/result/rcn/85426_en.html |access-date=4 July 2018 |archive-date=3 July 2018 |archive-url=https://web.archive.org/web/20180703133753/https://cordis.europa.eu/result/rcn/85426_en.html }}</ref><ref>{{cite web |title=Giant Hogweed (Heracleum mantegazzianum) – A pernicious invasive weed: Developing a sustainable strategy for alien invasive plant management in Europe. |url=https://www.uni-giessen.de/faculties/f09/institutes/ilr/loek/projects/finished-projects/giant-alien |access-date=4 July 2018 |archive-date=3 July 2018 |archive-url=https://web.archive.org/web/20180703133955/https://www.uni-giessen.de/faculties/f09/institutes/ilr/loek/projects/finished-projects/giant-alien }}</ref>

===New Zealand=== {{See also|Invasive species in New Zealand}}

New Zealand has had a series of Acts of Parliament relating to noxious weeds: the Noxious Weeds Act 1908,<ref>{{Cite web| title=Noxious weeds | year=1908 | url=http://www.enzs.auckland.ac.nz/docs/1908/1908C133.pdf | archive-url=https://web.archive.org/web/20220224030831/http://www.enzs.auckland.ac.nz/docs/1908/1908C133.pdf | archive-date=2022-02-24}}</ref> the Noxious Weeds Act 1950,<ref>{{Cite web|last1=McLintock|first1=Alexander Hare|last2=Arnold John Heine|first2=Antarctic Division|last3=Taonga|first3=New Zealand Ministry for Culture and Heritage Te Manatu|title=NOXIOUS WEEDS ACT OF 1950|url=https://teara.govt.nz/en/1966/weeds-and-noxious-plants/page-4|access-date=2022-02-24|website=An encyclopaedia of New Zealand, edited by A. H. McLintock, 1966.|language=en}}</ref> and the Noxious Plants Act 1978.<ref>{{Cite web|title=Noxious Plants Act 1978 (1978 No 15)|url=http://www.nzlii.org/nz/legis/hist_act/npa19781978n15234/|access-date=2022-02-24|website=www.nzlii.org}}</ref> The last was repealed by the Biosecurity Act 1993, which used words such as "pest", "organism" and "species", rather than "noxious". Consequently, the term "noxious weed" is no longer used in official publications in New Zealand.<ref>{{Cite web|title=Biosecurity Act 1993 No 95 (as at 28 October 2021), Public Act Schedule 3 enactments repealed – New Zealand Legislation|url=https://www.legislation.govt.nz/act/public/1993/0095/latest/DLM317125.html|access-date=2022-02-24|website=www.legislation.govt.nz}}</ref> According to this Act, control of the majority of problem weeds, now called 'pest plants', is the responsibility of Regional Councils, or unitary authorities, in a few councils. thumb|Broad-leaved dock. Some common noxious weeds in New Zealand are broad-leaved dock, English ivy, and ''Oxalis''.<ref name=":2">{{Cite web |date=2021-10-21 |title=Common Noxious Weeds in New Zealand |url=https://www.crewcut.co.nz/articles/garden-tips/noxious-weeds-nz |access-date=2024-05-07 |website=Crewcut Lawn & Garden |language=en-US}}</ref> These plants may be aesthetically pleasing, but they smother native plants and are hard to eradicate.<ref name=":2" />

=== United Kingdom === {{More citations needed section|date=April 2021}} The Weeds Act 1959 (7 & 8 Eliz. 2. c. 54) covers Great Britain,<ref>[http://www.legislation.gov.uk/ukpga/Eliz2/7-8/54 Weeds Act 1959]</ref> It is mainly relevant to farmers and other rural settings rather than the allotment or garden-scale growers. Five "injurious" weeds are listed. The word "injurious" means, in this context, harmful to agriculture, not liable to cause injury. All the species listed apart from ragwort are edible and appear in Richard Mabey's book Food for Free. They are all native plants. These are: * Spear thistle (''Cirsium vulgare'') * Creeping, or field, thistle (''Cirsium arvense'') * Curled dock (''Rumex crispus'') * Broad-leaved dock (''Rumex obtusifolius'') * Common ragwort (''Jacobaea vulgaris'')

The Department for Environment, Food and Rural Affairs (DEFRA) provides guidance for the removal of these weeds from infested land. Much of this is oriented towards the use of herbicides.

The act does not impose any automatic legal responsibility on landowners to control weeds or make growing them illegal, but they may be ordered to control them. Most common farmland weeds are not "injurious" within the meaning of the Weeds Act, and many such plant species have conservation and environmental value. The various UK government agencies responsible have a duty to seek a reasonable balance among different interests. These include agriculture, countryside conservation, and the general public.

Section 14 of the Wildlife and Countryside Act 1981 makes it an offence to plant or grow certain specified foreign invasive plants in the wild, listed in schedule 9 of the act, including Giant hogweed and Japanese knotweed. Some local authorities have by-laws controlling these plants.{{Citation needed|date=April 2017}} There is no statutory requirement for landowners to remove these plants from their property.

Northern Ireland is covered by the Noxious Weeds (Northern Ireland) Order 1977 (NISI 1977/52).<ref>[http://www.legislation.gov.uk/nisi/1977/52 Noxious Weeds (Northern Ireland) Order 1977]</ref> This mirrors the Great Britain legislation, and covers the same five species, with the addition of: * Wild oat (''Avena fatua'') * Wild oat (''Avena ludoviciana'')

===United States=== {{See also|Invasive species in the United States}} thumb|Ox-eye daisies. The federal government defines noxious weeds under the Federal Noxious Weed Act of 1974. Noxious weeds are also defined by the state governments in the United States.<ref>{{cite web|url=https://plants.usda.gov/java/noxiousDriver|title=Invasive and Noxious Weeds|publisher=USDA Natural Resources Conservation Service|access-date=25 August 2012}}</ref> Noxious weeds came to the U.S. by way of colonization.<ref>{{Cite web |date=2022-06-16 |title=Invasive Species as a Metaphor for Colonization |url=https://www.rewildingmag.com/invasive-species-as-a-metaphor-for-colonization/ |access-date=2024-05-03 |website=Rewilding Magazine |language=en}}</ref> Some wildflowers are lesser known noxious weeds. A few of them are banned in certain states.<ref name=":1">{{Cite web |title=Problem Plants: Noxious Weeds, Invasive Wildflowers, and Prohibited Plants |url=https://www.americanmeadows.com/content/wildflower-gardening/problem-plants |access-date=2024-05-03 |website=American Meadows |language=en}}</ref> For example, the Ox-eye daisy came to the Americas over in colonizers' seed bags and has become the common daisy seen at roadsides. It is prohibited in 10 states for agricultural use,<ref name=":1" /> and is the most heavily banned of any wildflower. <!-- Commented out per talk page.

For example, some of the plants on Idaho's noxious weed list that are harmful or poisonous are: * Leafy spurge: native to Eurasia. It has a milky latex throughout that can cause blisters and dermatitis in humans, cattle, and horses, and may cause permanent blindness if rubbed into the eye. * Poison hemlock: native to Europe. It contains highly poisonous alkaloids, toxic to all classes of domesticated grazing animals. * Russian knapweed: native to the Caucasus in southern Russia and Asia. It causes chewing disease in horses. * Tansy ragwort: native to Eurasia. All parts are poisonous; they cause liver damage in cattle and horses, while affecting sheep to a lesser extent. * Toothed spurge: native to the Great Plains region. A milky latex occurs throughout the plant and can cause blisters and dermatitis in humans, cattle, and horses. It may cause permanent blindness if rubbed into the eye. * Yellow starthistle: native to the Mediterranean basin area and Asia. It causes death and chewing disease in horses. * Yellow toadflax: native to Europe. It contains a poisonous hand that may be harmful to livestock. -->

==See also== * ''Caulerpa taxifolia'' * Invasive species * International Plant Protection Convention

==References== {{Reflist|2}}

==External links== ;Australia * [https://web.archive.org/web/20101202065957/http://weeds.org.au/noxious.htm Noxious Weeds List] at Weeds Australia

;New Zealand * {{cite encyclopedia | editor = McLintock, A. H. | encyclopedia = An Encyclopaedia of New Zealand | title = Noxious Weeds Act of 1950 | url = http://www.teara.govt.nz/en/1966/weeds-and-noxious-plants/4 | year = 1966}}

;United States * [https://web.archive.org/web/20060920215911/http://www.blm.gov/weeds/ Weeds] at the Bureau of Land Management (US) * [https://web.archive.org/web/20080920173136/http://www.aphis.usda.gov/plant_health/plant_pest_info/weeds/ Noxious Weed Program] at the US Department of Agriculture * {{youTube |id=3_iPnFVMRek |title=Killer Algae BBC Documentary Full}} — * {{youTube |id=Vd4rgN6MYtg |title=Attack of the killer algae - Eric Noel Muñoz}}

{{DEFAULTSORT:Noxious Weed}} Category:Weeds Category:Agricultural pests Category:Garden pests Category:Habitat