Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Datasheet

Crop production (pathway cause)

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Datasheet

Crop production (pathway cause)

Summary

  • Last modified
  • 27 July 2017
  • Datasheet Type(s)
  • Pathway Cause
  • Preferred Scientific Name
  • Crop production (pathway cause)
  • Overview
  • It has been estimated that over 70% of all invasive, exotic terrestrial plant species in the world were intentionally introduced into the new areas now invaded (

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Pictures

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PictureTitleCaptionCopyright
Jerusalem artichoke (Helianthus tuberosus) invading a garden where 10 tubers were planted four years earlier for food production. Burgundy (Bourgogne), France.
TitleJerusalem artichoke invading a garden
CaptionJerusalem artichoke (Helianthus tuberosus) invading a garden where 10 tubers were planted four years earlier for food production. Burgundy (Bourgogne), France.
CopyrightN.M. Pasiecznik
Jerusalem artichoke (Helianthus tuberosus) invading a garden where 10 tubers were planted four years earlier for food production. Burgundy (Bourgogne), France.
Jerusalem artichoke invading a gardenJerusalem artichoke (Helianthus tuberosus) invading a garden where 10 tubers were planted four years earlier for food production. Burgundy (Bourgogne), France. N.M. Pasiecznik
Kudzu vine (Pueraria lobata) being cultivated in raised mounds for its valuable and commercially traded tubers. Alongside is water hyancinth (Eichhornes crassipes) (left foreground) grown intentionally for pig fodder. Hai Duong Province, Vietnam.
TitleKudzu vine in cultivation
CaptionKudzu vine (Pueraria lobata) being cultivated in raised mounds for its valuable and commercially traded tubers. Alongside is water hyancinth (Eichhornes crassipes) (left foreground) grown intentionally for pig fodder. Hai Duong Province, Vietnam.
CopyrightN.M. Pasiecznik
Kudzu vine (Pueraria lobata) being cultivated in raised mounds for its valuable and commercially traded tubers. Alongside is water hyancinth (Eichhornes crassipes) (left foreground) grown intentionally for pig fodder. Hai Duong Province, Vietnam.
Kudzu vine in cultivationKudzu vine (Pueraria lobata) being cultivated in raised mounds for its valuable and commercially traded tubers. Alongside is water hyancinth (Eichhornes crassipes) (left foreground) grown intentionally for pig fodder. Hai Duong Province, Vietnam.N.M. Pasiecznik

Identity

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Preferred Scientific Name

  • Crop production (pathway cause)

International Common Names

  • English: Agriculture
  • Spanish: Agricultura
  • Portuguese: Agricultura

Local Common Names

  • English: Agronomy; Crop cultivation; Cropping; Cultivation; Farming; Mixed Farming

Overview

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It has been estimated that over 70% of all invasive, exotic terrestrial plant species in the world were intentionally introduced into the new areas now invaded (Pasiecznik, 2004) with crops second only in importance to ornamental species. For example, in Australia, 46% of serious weeds were deliberately introduced for particular purposes (Panetta, 1993) rising to 84% of the worst plant invaders in the Galapagos Islands (Tye, 1999). Regarding spread once introduced, Anderson (2007) noted that intentionally introduced crops were, and still are, bred for superior performance and survival in a specific environment, thus, introduced crops that are invasive will have a greater probability of spread than non-crop species that are unintentionally introduced. Figures for datasheets included in the Crop Protection Compendium (CABI, 2007) reveal that of 4390 ‘cultivated or useful plants’ included, 339 are also recorded as invasive (8%), or looking at it another way, of the 463 invasive plant datasheets, 339 (73%) are also recorded as ‘cultivated or useful’. There is, therefore, clearly a significant overlap.

Description

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Summary of organism types or species introduced
 
Common agricultural (or horticultural) food crop species appear on a number of invasive weeds lists, including: carrot, chicory, endive, Jerusalem artichoke, okra, parsnip, passion fruit, pumpkin, radish, rice, rye, sorghum, turnip - even tomato (Tye, 1999), and this list is by no means exhaustive. The inclusion of many of these crops as ‘invasive’ may surprise some, but this highlights the premise that a weed is just ‘a plant in the wrong place’. All those species listed have, at least somewhere, spread to, and within, ecologically sensitive areas. Others are herbs, condiments or medicinal plants, or aquatic crops including algae and seaweeds (e.g. Undaria pinnatifida) in marine environments, and leafy vegetables (e.g. water spinach, Ipomoea aquatica) in fresh water. There is also concern with the recent increase in interest in underutilized, neglected or orphan crops, often indigenous plants with local value that also have potential for wider cultivation or utilization. Many of such underutilized species also appear on invasive species lists, and Pasiecznik and Jaenicke (2009) provide 50 examples (including trees), highlighting the risks but also suggesting means to reduce them.

Fodder crops are another important group which includes many intentionally introduced invasive weeds, and in the grasses and sedges, contains a number of the world’s worst weeds, including elephant grass (Panicum maximum), kikuyu grass (Pennisetum clandestinum), molasses grass (Melinis minutiflora) and lolium ryegrass (Lolium temulentum). Several fodder shrubs have also become invasive after being introduced for dryland fodder banks, including saltbushes (Atriplex spp.) and Russian thistles (Salsola spp.). In Australia, 80% of the invasive grasses are thought to have been introduced by the government and escaped from research stations around the country (Pasiecznik, 2004). 

Of particular recent interest are biofuel crops, and there is a wealth of emerging literature indicating that very many of these are known invasive species, such as castor (Ricinus communis), giant reed (Arundo donax), red canary grass (Phalaris arundinacea), switchgrass (Panicum vulgatum), Miscanthus spp. and Spantina spp. (Low and Booth, 2008). Other weeds include fibre crops such as hemp (Cannabis sativa), or those for other industrial purposes. 

For species planted in agricultural landscapes for protective rather than productive purposes, see Hedges and windbreaks, Habitat restoration and improvement, and Forestry.
 
Principal processes

The main processes are the same for all invasive plants covered by this datasheet, which are in fact a defining factor. They were (1) selected for their perceived benefits as a food, fodder or for industrial purposes, (2) intentionally introduced internationally as crops, (3) escaped from cultivation either from farms or research plots, (4) naturalized and (5) spread locally becoming invasive weeds.

Geographical routes and corridors

Unlike accidental introductions, the long-distance introduction of crops as invasive species does not necessarily follow principal trade routes. Rather, they have been introduced from regions with similar environmental conditions, such as from South Africa to Australia, Europe to North America, or vice versa in each case. Early introductions would, however, have followed common transport routes such as roads, railways, ship and aircraft routes.

Human-mediated history

Plants useful to people have probably been transported since the earliest times, and scattered or planted where people settled during migrations. Although this is not ‘cultivation’ in the modern sense, this pathway, along with species that were accidentally introduced at the same time, probably included the first ever human-mediated introductions of what were to become weeds or (alien) invasive species. This process has carried on ever since, following human movement, increasing in frequency as trade routes appeared and travel and trade became more common.

Species Transported by Cause

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SpeciesNotesLong DistanceLocalReferences
Abelmoschus moschatus (musk mallow)Cultivated for its seeds (oil extraction) Yes Yes PROSEA (2016)
Abrus precatorius (rosary pea)Species is cultivated for ornamental, medicinal, and food additive purposes Yes Yes Motooka et al. (2003); Padua et al. (1999); Weber (2003)
Abutilon grandifolium (hairy Indian mallow) Yes
Abutilon hirtum (Indian mallow)Cultivated for fibres for ropes and clothing. Yes Yes Achigan-Dako (2010); Brussel (2004)
Acacia angustissima (prairie acacia)Intercropped to improve crop production. Yes Dzowela (1994); Paula et al. (2015)
Acacia auriculiformis (northern black wattle)Used for intercropping Yes Yes Turnbull and Awang (1997)
Acacia glauca (wild dividivi) Yes
Acacia mearnsii (black wattle)As a shade tree and a tree fallow Yes Yes Wiersum (1991)
Acanthospermum australe (spiny-bur) Yes Yes
Acarapis woodi (honeybee mite)Migratory beekeepers moved bees from southern US states northward to pollinate crops Yes Woodward and Quinn (2011)
Achatina fulica (giant African land snail)Accidental Yes Yes
Aegilops cylindrica Yes Yes
Aeginetia indica (forest ghost flower)Not mentioned in references but could be a possible way of seed movement Yes
Aeschynomene americana (shyleaf)Hay crop Yes Yes Cook et al. (2005)
African cassava mosaic virus (African cassava mosaic)ACMV is frequently spread via planting of contaminated cassava cuttings Yes Yes Thottappilly et al. (2003); Alabi et al. (2011; 2015)
Agave fourcroydes (henequen)Cultivated for fibre production Yes Yes Colunga-GarcíaMarín (2003)
Agave sisalana (sisal hemp)This species is cultivated as a source of fibre Yes Yes Rehm and Espig (1991)
Agave vivipara (Caribbean agave)Cultivated in Mexico to produce mezcal Yes Vargas-Ponce et al. (2009)
Ageratum conyzoides (billy goat weed)Weed in agricultural lands Yes PROTA (2016)
Ageratum houstonianum (Blue billygoatweed)Can spread in contaminated agricultural produce Yes Yes BioNET-EAFRINET (2016)
Agropyron cristatum (crested wheatgrass) Yes Yes Zlatnik (1999)
Agrostis capillaris (common bent) Yes Yes
Albizia adinocephala (cream albizia)Alibizia adinocephala is preferentially used as shade for coffee in parts of western Costa Rica, as it keeps its leaves during the dry season Yes Barrance et al. (2004)
Albizia carbonaria (carbonero) Yes Yes Barneby and Grimes (1996)
Albizia lebbeck (Indian siris)Nitrogen-fixing species; has been intentionally planted for shade for livestock and for cash crops such as coffee and tea, erosion control, and as an ornamental tree Yes Yes Ecocrop (2016)
Alectra vogelii (yellow witchweed)Ancient, probably with spread of cowpea cultivation in Africa. No studies on origins or movement Yes Yes
Aleurotrachelus atratus (palm-infesting whitefly) Yes
Alocasia cucullata (Chinese taro)Corms consumed by humans Yes Useful Tropical Plants (2019)
Alocasia macrorrhizos (giant taro)Planted for human consumption Yes Yes Manner (2011)
Aloe vera (true aloe)Widely cultivated for agricultural and medicinal uses Yes Yes USDA-ARS (2017)
Alopecurus myosuroides (black-grass) Yes Bond et al. (2007)
Alopecurus pratensis (meadow foxtail) Yes Yes USDA-ARS (2015)
Alpinia zerumbet (shell ginger)Grown as a spice crop Yes Yes UNIDO (2005)
Alternanthera sessilis (sessile joyweed)Weed Yes Yes Holm et al. (1997)
Alysicarpus vaginalis (alyce clover)Species widely cultivated in agricultural settings as a forage and cover crop and soil improver Yes Yes Duke (1981); Hanelt et al. (2001)
Amaranthus caudatus (love-lies-bleeding) Yes Yes Flora of North America Editorial Committee (2016)
Amaranthus dubius (spleen amaranth) Yes Yes Grubben (2004)
Amaranthus palmeri (Palmer amaranth)Seeds accidentally dispersed by agricultural practices Yes Yes Ward et al. (2013)
Amaranthus spinosus (spiny amaranth)Weed Yes Yes Motooka et al. (2003)
Amaranthus tricolor (edible amaranth) Yes Yes
Amaranthus tuberculatus (rough-fruited water-hemp)It is a weed of field crops; invasion favoured by certain farm practices Yes Yes Costea et al. (2005)
Ambrosia confertiflora Yes
Ambrosia tenuifolia (lacy ragweed)Weed in arable land Yes Yes Montagnani et al. (2017)
Amelanchier lamarckii (snowy mespilus) Yes NOBANIS (2009)
Anastrepha fraterculus (South American fruit fly) Yes Yes
Anastrepha grandis (South American cucurbit fruit fly) Yes Yes
Anastrepha ludens (Mexican fruit fly) Yes Yes
Anastrepha obliqua (West Indian fruit fly) Yes Yes
Anastrepha serpentina (sapodilla fruit fly) Yes Yes
Anastrepha striata (guava fruit fly) Yes Yes
Anastrepha suspensa (Caribbean fruit fly) Yes Yes
Andropogon glomeratus (bushy bluestem)Seed contaminant, machinery and imported soil Yes Yes PIER (2008); Quattrocchi (2006)
Andropogon virginicus (broomsedge) Yes
Anguina tritici (wheat seed gall nematode)Rare, accidental Yes
Annona reticulata (bullock's heart)Intentionally dispersed across the globe by humans from its American origin for cultivation. Yes Yes FAO EcoCrop (2014); Jansen et al. (1991); Orwa et al. (2009)
Anolis wattsi (Watts' anole)Jump dispersal at distances greater than 1 km/year in Trinidad Yes White and Hailey (2006)
Anoplolepis gracilipes (yellow crazy ant) Yes Yes
Argemone mexicana (Mexican poppy)A weed of cultivated land Yes Yes PROTA (2016)
Argemone ochroleuca (pale Mexican pricklypoppy) Yes BioNet-EAFRINET (2011)
Arion vulgaris (Spanish slug) Yes Yes Rabitsch (2006); Weidema (2006)
Arracacia xanthorrhiza (arracacha)Commercial crop and a cash crop for local farmers, mainly in tropical highlands Yes Yes Hermann (1997)
Arrhenatherum elatius (false oat-grass)Prevalent cause of introduction Yes Yes Pfitzenmeyer (1962)
Artemisia biennis (biennial wormwood)Accidental Yes Kegode and Darbyshire (2013)
Arthraxon hispidus (small carpetgrass) Yes Yes
Arthurdendyus triangulatus (New Zealand flatworm)Possibly from Scotland to the Faroe Islands with potatoes, also via manure, silage & machinery Yes Yes Boag et al. (1999); Mather and Christensen (1992); Moore et al. (1998); Murchie et al. (2003)
Artocarpus altilis (breadfruit)Cultivated for fruits and seeds Yes Yes Ragone (2011)
Arundo donax (giant reed) Yes Yes PIER (2007)
Averrhoa bilimbi (bilimbi)Species has been introduced as a food crop in all tropical parts of the world Yes Yes Morton (1987); Orwa et al. (2009); Samson (1991)
Axonopus fissifolius Yes Yes
Bactericera cockerelli (tomato/potato psyllid) Yes
Bactrocera cucurbitae (melon fly) Yes Yes
Bactrocera dorsalis (Oriental fruit fly) Yes Yes
Bactrocera zonata (peach fruit fly) Yes Yes
Bagrada hilaris (painted bug) Yes Yes Matsunaga (2014); LeVeen and Hodges (2015)
Bambusa bambos (giant thorny bamboo)Cultivated throughout the tropics for its culms Yes Yes PROTA (2015)
Banana bunchy top virus (bunchy top of banana) Yes Yes
Basella alba (malabar spinach)Small-scale production mixed with other vegetables Yes PROTA (2017)
Batis maritima (saltwort) Yes
Bidens pilosa (blackjack)Common weed of crops Yes Yes Holm et al. (1977)
Bipolaris victoriae (Victoria blight of oats) Yes Yes
Bixa orellana (annatto) Yes Yes Morton (1960)
Blighia sapida (akee apple)Grown as a fruit crop Yes Yes PROTA (2019); Rashford (2001)
Boerhavia diffusa (red spiderling)Weed on agricultural land Yes Yes Muzila (2006)
Brassica juncea (mustard)Deliberately introduced as a crop in most temperate and tropical areas Yes Office of the Gene Technology Regulator (2008)
Brassica rapa (field mustard)Cultivated worldwide Yes Yes Encyclopedia of Life (2018); Flora of North (2018)
Bromus hordeaceus (soft brome) Yes Yes Howard (1998); Smith (1968)
Bromus secalinus (rye brome)spreads as a contaminant of cereal seed Yes Afonin et al. (2016)
Buddleja asiatica (dog tail)Inter-island movement of ornamental plants, farming equipment and vehicles etc. Yes Yes
Bugula neritina (brown bryozoan) Yes
Bunias orientalis (Turkish warty-cabbage) Yes Yes Jehlik and Slavik (1968); Laivins et al. (2006)
Calacarus carinatus (purple tea mite) Yes Yes IPPC-Secretariat (2005)
Calopogonium caeruleum (jicama)Widely introduced as cover-crop Yes Yes Cook et al. (2005)
Cananga odorata (ylang-ylang)Species was introduced from Philippines to other Pacific Islands for crop production as early as 1770 Yes Yes Yusuf and Sinohin (1999)
Canavalia ensiformis (jack bean) Yes Yes Vargas-Ayala et al. (2000)
Canavalia gladiata (sword bean)Cultivated for its seeds and seed pods Yes Yes PROTA (2019)
Candidatus Liberibacter solanacearum (zebra chip) Yes Yes
Candidatus Phytoplasma asteris (yellow disease phytoplasmas) Yes Yes
Candidatus Phytoplasma australiense Yes Yes
Candidatus Phytoplasma phoeniciumTrade in plants or seedlings (probably) Yes Verdin et al. (2004)
Candidatus Phytoplasma rubi (witches'-broom phytoplasma disease) Yes Yes
Candidatus Phytoplasma trifolii (clover proliferation phytoplasma) Yes Yes
Canna indica (canna lilly) Yes Yes
Capsicum annuum (bell pepper)Cultivated as a crop plant for hundreds of years in the Americas, and now around the world Yes Yes Basu and De (2003)
Capsicum baccatum (pepper)Cultivated as a food and spice crop Yes Yes
Cardamine flexuosa (wavy bittercress)Agricultural weed in rice fields, crops and orchards Yes Yes Kudoh et al. (1993)
Carludovica palmata (Panama hat plant)For making hats and baskets Yes Yes
Cassia grandis (pink shower)Used as live fence, re-vegetation pioneer, and for intercropping systems Yes Yes ICRAF (2014)
Cecropia peltata (trumpet tree)As a shade tree for coffee plantations Yes Binggelli (1999)
Cenchrus biflorus (Indian sandbur) Yes Yes
Cenchrus ciliaris (Buffel grass) Yes Yes Marshall et al. (2012)
Centaurea melitensis (Maltese starthistle) Yes DiTomaso and Healy (2007); Dunn (1905)
Centaurea solstitialis (yellow starthistle) Yes
Ceratitis rosa (Natal fruit fly)Possible introduction through infested agricultural produce Yes Yes White and Elson-Harris (1994)
Chilo suppressalis (striped rice stem borer) Yes Yes
Chloris gayana (Rhodes grass)Forage for pasture and hay Yes Yes Cook et al. (2005)
Chloris virgata (feather finger grass)Potential seed contaminant Yes Yes USDA-ARS (2015)
Chondrilla juncea (rush skeletonweed) Yes
Chromolaena odorata (Siam weed)Common as a fallow species and probably spread during clearance, also to control Imperata Yes Yes Chevalier (1949)
Cinnamomum burmanni (padang cassia) Yes Yes Franck (2012)
Cinnamomum verum (cinnamon) Yes Yes
Citrus leprosis virus C (leprosis of citrus)Infected mites can be carried in seedlings from citrus nurseries to farmers' fields. Yes
Cleome rutidosperma (fringed spiderflower)Weed in agricultural land Yes Yes Holm et al. (1991)
Cleome viscosa (Asian spiderflower)Weed on rice and sugarcane plantations Yes Yes PROTA (2015)
Clerodendrum bungei (rose glorybower)Species is a weed of cultivated areas and can spread by portions of roots within soil Yes Yes
Clover yellow mosaic virus Yes Yes
Cnidoscolus aconitifolius (chaya) Yes Yes Ross-Ibarra and Molina-Cruz (2002)
Cocksfoot mottle virus (Cocksfoot mottle virus)Frequency of introduction not reported. Spread by vector and by mechanical transmission probable. Yes Yes Campbell and Guy (2001)
Coconut cadang-cadang viroid (cadang cadang disease)CCCVd is associated with plantation crops. Seed and pollen accessed internationally for coconut. Yes Yes Hanold and Randles (1998); Hanold and Randles (2003)
Cocos nucifera (coconut)Planted in plantations as overhead shade tree Yes Yes Chan and Elevitch (2006)
Codiaeum variegatum (garden croton) Yes Hettiarachchi et al. (2003)
Coix lacryma-jobi (Job's-tears)Planted as minor cereal. Introduced and cultivated in many countries as a food grain Yes Yes Schaaffhausen (1952); PROTA (2017)
Colletotrichum coccodes (black dot of potato)The pathogen can be spread on seed tubers, through soil and air Yes Yes Tsror et al. (1999a); Johnson and Miliczky (1993)
Colocasia esculenta (taro)Corms, stems and leaves are edible and planted for human consumption Yes Yes Safo-Kantaka (2004)
Coniothyrium glycines (red leaf blotch) Yes Hartman et al. (1987)
Corchorus hirtus (Orinoco jute) Yes Belay (2011)
Cordyline fruticosa (ti plant)Deliberate; migration; horticulture Yes Hinkle (2007); Simpson (2000)
Coriandrum sativum (coriander) Yes Yes
Cornu aspersum (common garden snail) Yes Yes
Crassocephalum crepidioides (redflower ragleaf)Consumed as a vegetable Yes Yes Denton (2004)
Crotalaria maypurensis (rattlebox weed)Green manure in plantations Yes Yes USDA-ARS (2015)
Crotalaria retusa (rattleweed)Fibre crop Yes Yes Prota4U (2013)
Crotalaria spectabilis (showy rattlepod)Contaminant in crop seeds Yes Yes Maddox et al. (2011)
Croton argenteus (silver July croton)Weed in agricultural lands Yes Yes Torres et al. (2010)
Cucumber green mottle mosaic virus Yes Yes
Cucumis anguria (West Indian gherkin)Cultivated for its fruits Yes Yes Wilkins-Ellert (2004)
Cucurbit aphid-borne yellows virus (Cucurbit aphid-borne yellows)Possible through dissemination of infected seedlings (rare, accidental) Yes Yes
Cucurbit yellow stunting disorder virus Yes Yes
Cuphea carthagenensis (Colombian waxweed) Yes Pio (1980)
Curtobacterium flaccumfaciens pv. flaccumfaciens (bacterial wilt of dry beans) Yes Yes
Cuscuta campestris (field dodder) Yes Yes
Cyanthillium cinereum (little ironweed)Probably dispersed as a seed and crop contaminant Yes Yes Holm et al. (1997)
Cymbopogon citratus (lemongrass)Cultivated as an industrial crop for its essential oils Yes Yes Oyen (1999)
Cyperus difformis (small-flowered nutsedge)As a contaminant Yes Yes Holm et al. (1979)
Dactylis glomerata (cocksfoot) Yes Yes
Dacus ciliatus (lesser pumpkin fly) Yes Yes
Datura ferox (fierce thornapple) Yes Yes Torres et al. (2013b)
Daucus carota (carrot)Wild carrot seed introduced as seed or grain contaminant Yes Yes
Deroceras invadens (tramp slug) Yes Yes NOBANIS (2015)
Deroceras laeve (meadow slug)Accidental Yes AnimalBase (2015)
Derris elliptica (tuba root)Cultivated for its roots Yes Yes Orwa et al. (2009)
Descurainia sophia (flixweed) Yes Rutledge and McLendon (1996)
Diaporthe eres (apple leaf, branch and fruit fungus)Associated with grapevine dieback; from apple rootstocks; from Vitis vinifera wood cankers; from different fruit trees such as apple, pear, cherry and plum Yes Yes Kaliterna et al. (2012); Udayanga et al. (2014); Lorenzini et al. (2016); Sessa et al. (2017); Abramczyk et al. (2018); Lorenzini and Zapparoli (2018); Ali et al. (2020)
Dickeya solani (black leg disease of potato)Accidentally introduced into across Europe and Israel through via infected potato seed tubers Yes Yes Toth et al. (2011)
Digitaria bicornis (Asian crabgrass)Present in crop fields, possibly a seed contaminant, soil contaminant and in cultivation waste Yes Yes
Digitaria ciliaris (southern crabgrass)Grass crop for haymaking Yes Yes Holm et al. (1979)
Digitaria fuscescens (yellow crab grass)In rice fields, possibly a seed contaminant Yes Yes Kosaka et al. (2006); PROTA (2016)
Dioscorea alata (white yam)Edible underground tubers (yams) and bulbils Yes Yes
Dioscorea bulbifera (air potato)Edible underground tubers (yams) Yes Yes ISSG (2012)
Dioscorea cayenensis (Guinea yam)widely cultivated species Yes Yes PROTA (2017)
Diplazium esculentum (vegetable fern)Cultivated in Australia for food Yes Yes PIER (2020)
Diplodia seriata (grapevine trunk disease) Yes Yes
Dreyfusia nordmannianae (silver fir adelges) Yes Yes Havill and Foottit (2007); Kirkeby-Thomsen (1998)
Dysphania ambrosioides (Mexican tea)Leaf vegetable, aromatic herb, industrial uses Yes Yes Prota4U (2013)
East Asian Passiflora virus Yes
Echinochloa crus-galli (barnyard grass)Common weed in rice Yes Yes Maun and Barrett (1986)
Echinochloa crus-pavonis (gulf cockspur grass)Weed in rice fields Yes Yes Michael (1983)
Echinochloa pyramidalis Yes
Emilia praetermissa (yellow thistle)Weed of agricultural lands Yes Yes PROTA (2020)
Epiphyas postvittana (light brown apple moth) Yes
Eragrostis unioloides (Chinese lovegrass)accidental Yes
Erigeron bellioides (bellorita)Weed of cultivated grounds Yes Yes Liogier and Martorell (2000)
Eriobotrya japonica (loquat)Grown for its edible fruits Yes Yes USDA-ARS (2018)
Erionota thrax (banana skipper) Yes
Erionota torus (banana skipper)Movement of banana planting material with early stages Yes Cock (2015)
Erythrina berteroana (coralbean)Planted as a shade tree in plantations Yes Yes Orwa et al. (2009)
Eugenia uniflora (Surinam cherry) Yes Yes
Euschistus heros (Neotropical brown stink bug)Commercial trade using roads; global warming Yes Yes Saluso et al. (2011)
Falcataria moluccana (batai wood) Yes Yes
Fallopia convolvulus (black bindweed)Contaminant in cereals crops Yes Yes Rutledge and McLendon (1996)
Ferrisia virgata (striped mealybug)Accidental introduction on plants; transport on used farm machinery Yes Yes
Festuca arundinacea (tall fescue)Widely used for fodder and turf Yes Yes USDA-NRCS (2016)
Festuca pratensis (meadow fescue) Yes Yes Darbyshire (2007)
Ficus benjamina (weeping fig)Unintentionally introduced by agriculture Yes Yes DAISIE (2014)
Ficus carica (common fig) Yes Yes Hanelt et al. (2001)
Ficus elastica (rubber plant)Species was formerly an economic crop for rubber production Yes Yes Coventry (1906); Strettell (1876); Tawan (2000); Whistler (2000)
Ficus pumila (creeping fig)Cultivated in Asia to make jelies Yes Yes Hanelt et al. (2001); Mabberly (2008)
Ficus religiosa (sacred fig tree)Sometimes grown as a fodder crop Yes Yes Orwa et al. (2009)
Fimbristylis littoralis (lesser fimbristylis)Agricultural weed Yes Yes Holm et al. (1977)
Flemingia lineata (wild hops)Used as green manure in Asia Yes
Flemingia strobilifera (wild hops) Yes
Foeniculum vulgare (fennel)Spice and medicinal plant Yes Yes
Forficula auricularia (European earwig)accidental Yes Yes Crumb et al. (1941); Weems and Skelley (2010)
Fragaria vesca (wild strawberry)Primary cause of introduction outside of the native range e.g. to Hawaii, Reunion and New Zealand Yes Yes ISSG (2013); PIER (2013)
Frankliniella occidentalis (western flower thrips) Yes Yes
Furcraea foetida (Mauritius hemp)A fibre plant and ornamental Yes Yes Kew (1917)
Fusarium oxysporum f.sp. cubense tropical race 4 (TR4) Yes
Fusarium oxysporum f.sp. medicaginis (fusarium wilt of alfalfa) Yes
Fusarium oxysporum f.sp. niveum (Fusarium wilt of watermelon) Yes Yes Martyn; 2014
Galinsoga parviflora (gallant soldier)Agricultural weed Yes Yes Damalas (2008)
Globodera pallida (white potato cyst nematode)Peru and Bolivia to Europe Yes Yes Turner and Evans (1998)
Globodera rostochiensis (yellow potato cyst nematode)Peru to Europe Yes Yes Turner and Evans (1998)
Glyceria maxima (reed sweet-grass) Yes Yes LAMBERT (1947)
Gomphrena globosa (globe amaranth) Yes Flora of Pakistan (2015)
Gossypium barbadense (Gallini cotton) Yes Yes PROTA (2017)
Grapevine red blotch virus (grapevine red blotch virus)The careless selection of infected grape propagation material results in long-distance or local spread of GRBV Yes Yes Sudarshana et al. (2015); Bahder et al. (2016a); Cieniewicz et al. (2017a; b; 2018a; 2019a); Dalton et al. (2019)
Grevillea robusta (silky oak)Extensively planted as “shade tree” in tea and coffee plantations Yes Yes Harwood et al. (1997)
Gymnandrosoma aurantianum (citrus fruit borer)The most likely mode of dispersal is in the movement of fruit, either in baggage or commodity consignments Yes Yes PestID (2018)
Halyomorpha halys (brown marmorated stink bug)Deliberate dispersal during search for host plant resources. Moves between agricultural crops throug Yes Yes Nielsen et al. (2013); Wiman et al. (2013b)
Haplaxius crudus (American palm cixiid) Yes
Haplodiplosis marginata (saddle gall midge) Yes Skuhravý et al. (1993)
Harmonia axyridis (harlequin ladybird) Yes Yes
Helianthus tuberosus (Jerusalem artichoke) Yes Yes
Heliocarpus donnellsmithii (majagua)Shade tree in coffee plantations Yes Yes Macía (1999)
Helminthotheca echioides (bristly oxtongue)Seeds spread via irrigation Yes Yes Tosso et al. (1986)
Heracleum sosnowskyi (Sosnowskyi's hogweed)Main cause of introduction to many countries/regions was cultivation as a fodder crop Yes Yes EPPO (2008); Kabuce (2006); Nielsen et al. (2005)
Heterodera glycines (soybean cyst nematode) Yes Yes
Hirschfeldia incana (shortpod mustard) Yes South East Natural Resources Management Board (2009)
Holcus lanatus (common velvet grass) Yes Yes
Hop stunt viroid (hop stunt viroid) Yes Yes Hadidi et al. (2003)
Hymenula cerealis (Cephalosporium stripe)Movement in infested host debris through natural processes or human intervention. Yes Yes Bockus et al. (2010)
Hyoscyamus niger (black henbane)Grown worldwide as a medicinal plant Yes Yes
Hypothenemus hampei (coffee berry borer) Yes Yes
Hyptis suaveolens (pignut) Yes Cullen et al. (2012)
Indigofera hirsuta (hairy indigo)Used as a cover crop and as 'green manure' Yes Yes Djarwaningsih (1997)
Ipomoea nil (white edge morning-glory)Agricultural weed Yes Yes Vibrans (2017)
Iris yellow spot virus (iris yellow spot)Via seedlings, infected bulbs, and thrips movement. Virus overwinters in volunteer onions and weeds Yes Yes Gent et al. (2006); Pappu et al. (2009)
Isatis tinctoria (dyer's woad)Historically extensive deliberate introductions Yes Yes Hurry (1930)
Jatropha curcas (jatropha) Yes Pitt (1999)
Jatropha gossypiifolia (bellyache bush) Yes
Juncus ensifolius (swordleaf rush)Accidental contaminant in hay, peat or soil Yes Yes Kirschner (2002)
Kuehneola uredinis (Cane and leaf rust) Yes Yes Ellis et al. (1991)
Lagenaria siceraria (bottle gourd)Grown for its fruits Yes Yes PROTA (2018)
Launaea intybacea (bitter lettuce)Weed in agricultural land Yes Yes Liogier (1997)
Lawsonia inermis (Egyptian privet)Commercial production of henna dye Yes Yes USDA-ARS (2017)
Lemna aequinoctialis (lesser duckweed)In rice fields Yes Yes Pinke et al. (2014)
Lepidium virginicum (Virginian peppercress)As grain contaminant Yes Yes Online Atlas of the British and Irish Flora (2016)
Leptochloa fusca (sprangletop)Weed of agricultural lands Yes Yes Flora of China Editorial Committee (2018)
Leptospermum scoparium (manuka) Yes Yes
Leucaena leucocephala (leucaena) Yes Yes
Leucanthemum vulgare (oxeye daisy)Via contaminated pasture seed Yes Yes
Limnocharis flava (yellow bur-head) Yes
Linaria vulgaris (common toadflax)As contaminant in crop seed Yes
Liriomyza cicerina Yes Yes Spencer (1973)
Luffa acutangula (angled luffa) Yes Yes PROTA (2016)
Lumbricus rubellus Yes Yes
Lumbricus terrestris Yes Yes
Lupinus angustifolius (narrow-leaf lupin)Cultivated as a legume pulse Yes Yes USDA-ARS (2017)
Lupinus polyphyllus (garden lupin)Deliberate Yes Yes NOBANIS (2015)
Lygodium flexuosum (maidenhair creeper)It might be dispersed by agricultural practices as it is a weed of various crops Yes Yes USDA-APHIS-PPQ (2009)
Malva pusilla (round-leaved mallow)Crop seed contaminant Yes Yes Makowski and Morrison (1989)
Mangifera indica (mango)Fruit production Yes Yes Bally (2006)
Manilkara zapota (sapodilla) Yes Yes
Maranta arundinacea (arrowroot)Cultivated for its roots Yes Yes PROSEA (2018)
Medicago lupulina (black medick)Weed in agricultural land; seed contaminant Yes Yes USDA-ARS (2017)
Melaleuca quinquenervia (paperbark tree) Yes Dray et al. (2006)
Melilotus albus (honey clover)Grown as fodder in many places Yes Yes Gucker (2009)
Melilotus officinalis (yellow sweet clover) Yes Yes
Melinis repens (natal redtop)Hay crop and pasture grass introduction to Americas, Australia Yes Langeland et al. (2008)
Meloidogyne enterolobii (Pacara earpod tree root-knot nematode)rare Yes
Meloidogyne incognita (root-knot nematode)Movement of soil on machinery. Movement of infected plant material. Yes Yes
Mentha pulegium (pennyroyal)Cultivated as a useful plant Yes Yes PFAF (2013)
Microlaena stipoides (meadow rice grass, meadow ricegrass)Deliberate in natural range as pasture; accidental as seed contaminant Yes Yes Biological Records Centre (2012); Huxtable and Whalley (1999)
Microstegium vimineum (Nepalese browntop) Yes Warren et al. (2010)
Mikania micrantha (bitter vine) Yes Yes
Mimosa diplotricha (creeping sensitive plant) Yes Yes DAF (2016); Parsons and Cuthbertson (1992)
Molothrus ater (brown-headed cowbird) Yes
Momordica charantia (bitter gourd)Cultivated for edible fruits Yes Yes Holm et al. (1997)
Moniliophthora roreri (frosty pod rot)Dominant dispersal, accidental, associated with cocoa production Yes
Monochamus leuconotus (white coffee stem borer)Wide distribution - destructive pest. Yes Schoeman (1994)
Monochoria hastata (hastate-leaved pondweed)Weed of rice fields. No information available, but possible from rice cultivation practices Yes Yes Boonkerd et al. (1993)
Mononychellus tanajoa (cassava green mite)Accidental, common pathway Yes Yaninek et al. (1989b)
Morinda citrifolia (Indian mulberry)Cultivated for its fruits and leaves Yes Yes Orwa et al. (2009)
Moringa oleifera (horse radish tree) Yes Yes PROTA (2017)
Morus nigra (black mulberry)Widely cultivated Yes Yes Hanelt et al. (2001); Randall (2012); Wyk BEvan (2005)
Mucuna pruriens (velvet bean)Cultivated as a cover crop and fodder/forage crop Yes Yes Duke (1981)
Nasturtium microphyllum (one-row watercress) Yes
Nelsonia canescens (blue pussyleaf)Weed in agricultural land Yes Yes Randall (2012)
Neonotonia wightii (perennial soybean)Widely introduced forage crop Yes Yes Cook et al. (2005)
Nicotiana tabacum (tobacco) Yes Yes
Ocimum gratissimum (African basil)Cultivated for the essential oil extracted from leaves and stems Yes Yes Orwa et al. (2009)
Ocimum tenuiflorum (holy basil)Cultivated both commercially and locally for use as culinary and medicinal herb Yes Yes
Oldenlandia corymbosa (flat-top mille graines)Weed in paddy fields and farmlands Yes Yes Flora of China Editorial Committee (2018)
Oldenlandia lancifolia (calycose mille graines)Weed of paddy fields and cereal crops Yes Yes Randall (2017)
Olea europaea subsp. cuspidata (wild olive) Yes Yes
Olea europaea subsp. europaea (European olive)Grown as a cash crop in many countries Yes Yes
Opogona sacchari (banana moth) Yes
Opuntia ficus-indica (prickly pear) Yes Yes
Orobanche cernua (nodding broomrape)Potential introduction on contaminated crop seed Yes
Orobanche cumana (sunflower broomrape)Spread in contaminated sunflower seed Yes Yes
Orobanche ramosa (branched broomrape) Yes Yes Jacobsohn (1984)
Oryza barthiiCommon on a local basis. Rare at distance but potential. Yes Yes
Paederia foetida (skunkvine)Grown as a medicinal crop Yes Yes Nath et al. (2015)
Paracoccus marginatus (papaya mealybug)Local trade in live planting material Yes Macharia et al. (2017)
Parentucellia viscosa (yellow glandweed) Yes Yes
Parthenium hysterophorus (parthenium weed) Yes Yes PAG (2000)
Paspalum conjugatum (buffalo grass)Weed in crop, tree plantations and pastures Yes Yes Queensland Government (2018)
Paspalum distichum (knotgrass) Yes Yes
Paspalum urvillei (Vasey grass)Widely introduced as a pasture grass around the world Yes Bowen and Hollinger (2002); Randall (2012)
Paspalum vaginatum (seashore paspalum)Via cultivation equipment Yes
Passiflora edulis (passionfruit)Garden and crop plant Yes Yes Akamine et al. (1974); Martin and Nakasone (1970)
Passiflora tarminiana (banana passionfruit)Cultivated for fruit and flowers Yes Yes Coppens d'Eeckenbrugge et al. (2001)
Passion fruit woodiness virus (passionfruit woodiness disease)Accidental with exchange of live Passiflora plant material. International movement is now restricted and requires permits Yes Yes Baker et al. (2014)
Pastinaca sativa (parsnip)Deliberate dispersal as a crop species. Less common now Yes Yes Cain et al. (2010)
Pear blister canker viroid Yes Yes
Pectobacterium brasiliense (soft rot and blackleg of ornamentals and potato) Yes Yes
Pectobacterium parmentieri (black leg disease of potato) Yes Yes
Pelargonium odoratissimum (apple geranium)Cultivated for use in medicine, food preparations, essential oil, and as an ornamental plant. Yes Yes Hanelt et al. (2001); PFAF (2014); USDA-ARS (2014)
Pennisetum clandestinum (Kikuyu grass)Widely introduced as a forage crop Yes
Pennisetum polystachion (mission grass)As a catch crop for stemborers Yes Yes Matama-Kauma et al. (2006); Ndemah et al. (2002)
Peronosclerospora philippinensis (Philippine downy mildew of maize)Movement of infected seeds or some abiotic agents like wind and air Yes Yes Murray (2009)
Peronosclerospora sorghi (sorghum downy mildew) Yes Yes Frederiksen et al. (1970); Toler et al. (1959)
Persicaria chinensis (Chinese knotweed)Weed in tea plantations Yes Yes Tjitrosemito and Jaya (1990)
Phaseolus lunatus (lima bean)Cultivated for its edible seeds Yes Yes PROTA (2014)
Phenacoccus solenopsis (cotton mealybug) Yes
Phleum pratense (timothy grass) Yes Yes
Physalis peruviana (Cape gooseberry) Yes Yes
Pimenta dioica (allspice)Species is used as a crop in many countries Yes Yes Parthasarathy et al. (2008)
Planococcus citri (citrus mealybug)Accidental introduction on imported plants, transport on used farm machinery Yes Yes Gerson (2016)
Plasmodiophora brassicae (club root)P. brassicae resting spores can survive upwards of fifteen years. Infested soil can be easily moved on machinery, livestock, people, or by the environment. Yes Yes Wallenhammar (1996)
Plectranthus amboinicus (Indian borage)Widely cultivated in home gardens and commercially for culinary, medicinal, and ornamental use Yes Yes USDA-ARS (2014)
Plum pox virus (sharka)Budwood exchange. Yes
Plutella xylostella (diamondback moth) Yes
Poa annua (annual meadowgrass) Yes Yes Holm et al. (1997)
Poa compressa (Canada bluegrass) Yes Hitchcock (1951)
Polygonum arenastrum (common knotweed)Accidental Yes Burnett and Moore (2014)
Pomacea maculataMay have been introduced accidentally with other species Yes Mochida (1991); Teo (2004)
Portulaca pilosa (kiss-me-quick)a seed contaminant of hay and grain Yes Yes Ridley (1930)
Pseudocercospora fuligena (black leaf mould) Yes
Pseudococcus viburni (obscure mealybug)On infested plants e.g. grapevines, fruit trees, and on fruits Yes
Pseudomonas cichorii (bacterial blight of endive) Yes Yes
Pseudorasbora parva (topmouth gudgeon) Yes Yes Copp et al. (2005a)
Pterocarpus indicus (red sandalwood)Planted as windbreak and soil improver (nitrogen fixing) in croplands Yes Yes Thomson (2006)
Ralstonia solanacearum (bacterial wilt of potato)Frequent accidental or deliberate for use as biocontrol agent for Hedychium gardnerianum in tropical Yes Yes
Rhamphicarpa fistulosaPresumably dispersed through informal (farmer-to-farmer) seed exchange Yes
Rhaponticum repens (Russian knapweed)Accidental introduction with other species Yes Yes
Rosa rugosa (rugosa rose)For commercial production Yes Yes Weidema (2006)
Rottboellia cochinchinensis (itch grass)Contaminated farm machinery Yes Arkansas State Plant Board (2008)
Rubus ellipticus (yellow Himalayan raspberry) Yes Yes Gardner (1999)
Rubus niveus (Mysore raspberry) Yes Yes ISSG (2014)
Sambucus canadensis (American black elderberry)Cultivated for its fruits Yes Yes Stevens (2001)
Sansevieria hyacinthoides (African bowstring hemp)Used as a fibre crop Yes Yes Langeland et al. (2008)
Sansevieria trifasciata (mother-in-law’s tongue)Fibre crop Yes Yes ISSG (2012)
Sclerophthora rayssiae var. zeae (brown stripe downy mildew of maize)Unless seed is contaminated with mycelium or oospores Yes Singh et al. (1967); Singh and Renfro (1971)
Sechium edule (chayote)Cultivated for its fruits, tubers, seeds and young shoots Yes Yes PROSEA (2018)
Senna hirsuta (hairy senna)Green manure and shade trees in coffee plantations Yes
Senna italica (Senegal senna)Cultivated for its leaves, flowers and seeds Yes Yes Okeyo and Bosch (2007)
Senna spectabilis (whitebark senna)Plant has been introduced and cultivated widely Yes Yes PIER (2014)
Senna surattensis (golden senna)Grown as hedge and shade tree in plantations and agricultural areas Yes Yes Hanelt et al. (2001); Little and Skolmen (1989); Sosef and Maesen (1997)
Sesamia cretica (greater sugarcane borer) Yes Yes
Sesbania sericea (silky sesban)Used as green manure Yes Yes Ipor and Oyen (1997)
Sesbania sesban (sesban)Intercropping Yes Yes Gutteridge and Shelton (1995)
Setaria verticillata (bristly foxtail) Yes Yes
Sida acuta (sida) Yes Yes Smith (2002)
Silene gallica (common catchfly)Agricultural machinery Yes
Silene latifolia subsp. alba (white campion)Seed contaminant Yes Yes Alberta Weed Monitoring Network (2014)
Silybum marianum (variegated thistle) Yes Yes
Solanum capsicoides (cockroach berry)Prevalent in cow pastures in Florida Yes Yes Markle et al. (2014)
Solanum elaeagnifolium (silverleaf nightshade)Benefits from cultivating soil and spread by agricultural equipment Yes Yes
Solanum quitoense (naranjilla)Fruit crop Yes Yes USDA-ARS (2017)
Solanum rostratum (prickly nightshade)Seed contaminant Yes Yes Wiersema and León (1999)
Solanum sisymbriifolium (sticky nightshade)Cultivated as a trap crop Yes Yes ISSG (2020)
Solanum tuberosum (potato)A staple crop in many countries Yes Yes
Solanum viarum (tropical soda apple)Movement of cattle, manure, hay within USA Yes Yes Mullahey et al. (2006)
Solenopsis invicta (red imported fire ant)Equipment or associated planting material-accidental Yes ISSG (2014)
Solenopsis richteri (black imported fire ant) Yes Yes Taber (2000)
Sonchus asper (spiny sow-thistle)Agricultural weed Yes Yes Vibrans (2009)
Sonchus oleraceus (common sowthistle)Agricultural weed Yes Yes Holm et al. (1977)
Sorghum halepense (Johnson grass) Yes Yes
Sphagneticola trilobata (wedelia) Yes Yes
Spodoptera frugiperda (fall armyworm) Yes Yes
Spodoptera litura (taro caterpillar) Yes Yes
Sporisorium pulverulentum (Sporisorium smut of wild Saccharum) Yes Yes
Sporobolus pyramidalis (giant rat’s tail grass) Yes Yes
Stenotaphrum secundatum (buffalo grass)Agricultural machinery Yes
Stictococcus vayssierei (cassava brown root scale) Yes Yes Ngeve (2003a)
Strawberry necrotic shock virus (Strawberry necrotic shock virus) Yes Yes
Striga asiatica (witch weed)Risk of transfer with crop seeds and produce Yes Yes
Sugarcane grassy shoot phytoplasma (grassy shoot of sugarcane) Yes Yes
sugarcane white leaf phytoplasma (white leaf of sugarcane) Yes Yes
Sus scrofa [ISC] (feral pig) Yes Yes Hopf (1979)
Syzygium malaccense (Malay apple)Cultivated pantropically for its edible fruits Yes Yes Little and Skolmen (1989); Morton (1987)
Tagetes erecta (Mexican marigold)Cultivated for the pigment in its flowers Yes Yes Heuzé et al. (2017)
Tamarindus indica (tamarind)Extensively cultivated on a plantation scale for its fruits Yes Yes Orwa et al. (2009)
Tapinoma melanocephalum (ghost ant)Most frequently observed entering New Zealand on fresh produce, such as coconuts Yes Yes Harris et al. (2005)
Tephrosia candida (white tephrosia) Yes Yes
Thecaphora frezii (peanut smut)Seed trade, agricultural machinery and harvesting activities can disperse the pathogen between fields Yes Cazón (2015); Rago et al. (2016)
Tithonia diversifolia (Mexican sunflower)Weed Yes Yes
Tithonia rotundifolia (red sunflower)Agricultural weed Yes Yes Vibrans (2009)
Tomato apical stunt viroid Yes Yes
Tomato brown rugose fruit virus (Tomato brown rugose fruit virus) Yes Yes
Tomato leaf curl New Delhi virus (Tomato New Delhi virus)Seasonal crop rotation Yes Yes
Tomato yellow leaf curl virus (leaf curl)Switch of hosts during and after harvest. Yes Yes Cohen et al. (1988)
Trifolium angustifolium (narrow-leaf clover)Used as a green manure Yes Driouech et al. (2008)
Trifolium hybridum (alsike clover)Used for hay, fodder and green manure Yes
Tuta absoluta (South American tomato pinworm)Long-distance: T. absoluta was accidentally introduced by airfreight transporting tomatoes from Chile to Spain. Local: In the northern coast of Africa and the sub-Saharan region, T. absoluta spread southwards due to the high number of plantations of tomato and other solanaceous species. Yes Yes Guillemaud et al. (2015); Sylla et al. (2017)
Typha domingensis (southern cattail)Seeds attach to mud on agricultural implements. Yes Parsons and Cuthbertson (1992)
Urena lobata (caesar weed)Intentionally introduced in many countries as a fibre crop Yes Yes Langeland et al. (2008)
Urena sinuata (bur mallow)Used as a fibre crop Yes Yes Maiti (1979)
Urochloa platyphylla (broadleaf signalgrass)Introduced as a contaminant in grass and crop-seeds Yes Yes USDA-ARS (2014)
Urochloa reptans (sprawling signalgrass)Agricultural weed Yes Yes USDA-ARS (2018)
Urtica dioica (stinging nettle)grown as a fibre crop Yes Yes
Ventenata dubia (North Africa grass)Accidental, seeds in crop seed or hay Yes Yes
Verbena rigida (stiff verbena)Weed in cotton crop fields Yes Johnson and Hazlewood (2002)
Vicia villosa (hairy vetch) Yes Yes Heuze et al. (2014)
Vulpia bromoides (squirreltail fescue)Possibly spread in impure pasture grass seed Yes Yes
Wasmannia auropunctata (little fire ant)Equipment or associated planting material - accidental Yes Yes
Wheat streak mosaic virus (wheat streak)Volunteer wheat plays a large part in distribution and epidemiology as a reservoir host for WSMV. Yes Thomas and Hein (2003)
Xanthomonas citri (citrus canker) Yes
Xanthomonas translucens pv. translucens (bacterial leaf streak of barley) Yes Yes Sapkota et al. (2020)
Xanthomonas vasicola pv. vasculorum (bacterial leaf streak of corn)Mechanisms of introduction and spread still unknown Yes
Xanthosoma sagittifolium (elephant ear)Tubers are consumed by humans Yes Yes Manner (2011)
Xylophilus ampelinus (canker of grapevine) Yes Yes
Youngia japonica (oriental false hawksbeard)Agricultural weed Yes Yes Vibrans (2018)
Zeuxine strateumatica (soldier’s orchid)In agricultural land and rice fields Yes Yes Encyclopedia of Life (2018)
Zingiber montanum (cassumunar ginger)Widely cultivated for various medicinal purposes and as flavouring agent in food preprations Yes Yes Acevedo-Rodriguez and Strong (2005); Ravindran and Babu (2005); Wolff et al. (1999)
Zingiber officinale (ginger)Major export crop Yes Yes
Ziziphus spina-christi (Christ's thorn jujube)Often cultivated for its fruits Yes Yes Orwa et al. (2009)
Zoysia matrella (Manila grass)Turfgrass production in tropical and subtropical regions Yes FAO (2015)

Management

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That all crops are intentionally introduced has significant impacts for attempting to control entry in the traditional sense of phytosanitary measures, i.e. not being accidentally introduced as crop contaminants as are many arthropod pests and crop pathogens. As most invasive plants have been introduced for perceived benefits in terms of production (e.g. as agricultural crops for food, fodder or fibre, fuel or timber trees or medicinal plants), for protection (e.g. for hedging or erosion control) or as ornamental species, the pathway for all these can be regarded as much the same, though the type of bodies, organizations or individuals responsible (the ‘vector’) may differ, e.g. commercial nurseries, governments, plant collectors, manufacturers, etc. The distinctions between such different 'vectors' are important when considering means of regulation: whereas most of these are transparent legal introductions through regulated channels, others are legal or illegal, via baggage or the postal service.

One means being increasingly suggested as a way to reduce or eliminate the risk of invasion, is the use of sterile cultivars or varieties. Some traits such as high male/female fertility are advantageous in the wild and could enable the evolution of cultivated crops into invasive weeds, whereas others such as sterility are not expected to confer invasiveness. For a list of traits in ornamental horticulture or food crops, which may be correlated with invasiveness, refer to Anderson (2007; Table 6-1, p 187-188). Anderson et al. (2006) proposed that trait-based selection of potential crop species be coupled with species design, to create a 'non-invasive crop ideotype' as a method to reduce invasiveness during the domestication process. The ideotype should be flexible and should adjust to species- and crop-specific traits to account for the intended use, e.g. developing sterile cultivars would have little effect in reducing invasiveness if the crop can spread vegetatively. Also, a non-invasive crop ideotype may also increase the direct participation of plant breeders in reducing the invasive potential of crops (Anderson et al., 2006).

Breeding for sterile triploids was suggested by Anderson et al. (2006) and Anderson (2007); however, sterile triploids could naturally double-up to form self-fertile hexaploids which may well be even more invasive than the original diploid parents (C. Hughes, Oxford University, UK, pers. comm., 2004). Male sterility systems are routinely used in seed production of some vegetable and oilseed crops (e.g. onion, canola) to avoid costly emasculation of the female (seed) parent during the production of hybrid seed (Peterson and Foskett, 1953) though the use of such techniques in the production of annual crops is unknown.

Industry self-regulation is proposed by Anderson (2007) and this is beginning to have impacts with the introduction and spread of ornamental plants, especially in Europe, North America and Oceania. Extension programmes aimed at educating the public to buy only native species (if available) and the plant trade to stock more alternative native species, are having an impact. However, this is unlikely to impact the production of food, fodder or fuel crops, with the exception of the promotion of indigenous, local crops in the developing world rather than a dependence on less suitable exotic commodity crops (Pasiecznik and Jaenicke, 2009).

Increased observation, for early identification of escapees, or weediness in introduced crops, could have an impact in catching crops that become invasive plants before they are widespread, or at least highlight those that exhibit ‘invasive’ characteristics. For example, while not regarded as invasive, oilseed rape (B. napus var. napus) is certainly one common temperate crop that is often found along roadsides and other open ground or fallow, and would possibly be more prevalent in subsequent crops in the rotation were it not for the use of herbicides.

References

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American Seed Trade Association (ASTA), 1999. Position statement on invasive species. Position statement on invasive species. Virginia, USA: American Seed Trade Association, unpaginated. http://www.nasda.org/joint/ASTAinvasivespecies.htm

Anderson NO, 2007. Prevention of invasiveness in floricultural crops. In: Flower Breeding and Genetics [ed. by Anderson, N. O.]., The Netherlands: Springer, 177-214.

Anderson NO; Gomez N; Galatowitsch SM, 2006. A non-invasive crop ideotype to reduce invasive potential. Euphytica, 148(1/2):185-202.

CABI, 2007. Crop Protection Compendium. Crop Protection Compendium. Wallingford, UK: CABI, unpaginated.

Ferry N; Gatehouse MR, 2009. Environmental impact of genetically modified crops. CAB International, 432 pp.

Gray AJ, 2005. Hybridization between crops and wild plants in the age of genetic engineering: new risks or new paradigms? American Journal of Botany, 92:768-771.

International Seed Federation (ISF), 2008. What is an invasive species? What is an invasive species. Nyon, Switzerland: International Seed Federation, unpaginated. http://www.worldseed.org/en-us/international_seed/others.html

Low T; Booth C, 2008. The weedy truth about biofuels. The weedy truth about biofuels. Melboune, Australia: Invasive Species Council, 46 pp. http://www.invasives.org.au/downloads/isc_biofuels_revised_mar08.pdf

Panetta FD, 1993. A system of assessing proposed plant introductions for weed potential. Plant Protection Quarterly, 8(1):10-14.

Pasiecznik NM, 2004. Pathways for plant introduction. Invasive plant overviews, invited paper. CABI, Crop Protection Compendium. Wallingford, UK: CAB International, unpaginated.

Pasiecznik NM; Jaenicke H, 2009. Underutilised crops and invasive species - understanding the links. Acta Horticulturae, 806:587-594.

PETERSON CE; FOSKETT RL, 1953. Occurrence of pollen sterility in seed fields of Scott County Globe onions. Proceedings. American Society for Horticultural Science, 62:443-48.

Raybould A; Gray AJ, 1994. Will hybrids of genetically modified crops invade natural communities? Trends in Ecology & Evolution, 9(3):85-89.

Reichard SH; White P, 2001. Horticultural introductions of invasive plant species: a North American perspective. In: The Great Reshuffling: Human Dimensions of Invasive Alien Species [ed. by McNeely, J. A.]. Gland, Switzerland: IUCN, 161-170.

Tye A, 1999. Invasive plant problems and requirements for weed risk assessment in the Galapagos Islands. In: 1st International Workshop on Weed Risk Assessment. 16-18 February 1999, Adelaide, Australia. unpaginated. http://www.hear.org/iwraw/1999/papers/tyefinal.pdf

Contributors

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4/16/2009 Original text by:

Nick Pasiecznik, Consultant, France