Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide


Soil, sand and gravel (pathway vector)



Soil, sand and gravel (pathway vector)


  • Last modified
  • 13 July 2017
  • Datasheet Type(s)
  • Pathway Vector
  • Preferred Scientific Name
  • Soil, sand and gravel (pathway vector)
  • Overview
  • This pathway has been noted as an important vector, particularly for some invasive plants but also for a range of insects and plant pathogens, repeatedly in certain situations. For plants, these are the intentional inter-island movement of build...

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Preferred Scientific Name

  • Soil, sand and gravel (pathway vector)

International Common Names

  • English: Aggregate; Building material; Compost; Manure; Soil, sand, gravel; Substrate
  • Spanish: Terra, arena, grava
  • French: Terre, sable, gravion
  • Portuguese: Terra, areia, cascalho


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This pathway has been noted as an important vector, particularly for some invasive plants but also for a range of insects and plant pathogens, repeatedly in certain situations. For plants, these are the intentional inter-island movement of building materials such as in the Pacific Ocean particularly and along rivers such as the Rhine and Danube in Europe that carry considerable trade in such commodities. Accidental introduction via movement of dredged materials, substrata for greenhouses or mushroom compost also have associated risks, the latter two especially for pests and pathogens. Movement of soil, sand and gravel is an important pathway both for accidental international introductions, and dispersal within an area, though it is rarely the principal means for introduction or spread.


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Summary of organism types or species introduced

Plants are the most frequently recorded invasive organism type associated with this pathway, most as seed but occasionally as stolons, rhizomes, root fragments or other vegetative material (see ‘Principle processes’ below).

Nematodes can be spread through soil movements. Species of the following 25 genera are recorded from the CPC (2009) as having soil as a means of dispersal: Achlysiella, Anguina, Aphasmatylenchus, Aphelenchoides, Belonolaimus, Ditylenchus, Globodera, Helicotylenchus, Hemicriconemoides, Heterodera, Hirschmanniella, Hoplolaimus, Longidorus, Meloidogyne, Nacobblus, Paralongidorus, Paratrichodorus, Pratylenchus, Punctodera, Radopholus, Rotylenchulus, Trophotylenchulus, Tylenchorhynchus, Xiphinema and Zygotylenchus.

Other soil-borne pathogens can also be expected to be dispersed with soil movements, including bacteria.

Agricultural practices of irrigation, pruning and substratum reutilization dispersed Xanthomonasaxonopodis pv. begoniae (Grijalba et al., 1998), and blood disease bacterium of banana is capable of dispersal in soils, and persisted for over a year in soil contaminated by diseased plant remnants and could infect healthy plants following experimental soil inoculation (Gäumann, 1923). Several species of Pseudomonas are also recorded as being locally spread by soil movements.

A number of fungal pathogens are also specifically noted, where fruiting bodies (oospores, ascospores, etc.) are dispersed, often if attached to crops but also in wholesale soil movements. These include Phytophthora porri, Pseudoperonosporacannabina in heavy soils (McPartland et al., 2000), Microdochium panattonianum in soil from infected fields (Galea and Price, 1988), and Streptomyces ipomoeae persists in soil for years to decades and is resistant to desiccation.

In addition, Potato mop-top virus is spread with soil from fields where the virus is endemic (Sandgren, 1995), and the putative virus Sugarcane dwarf disease is also spread by the same means (Magarey, 2000).

Insects are another group, in different stages of development. Puperea of many Diptera can be dispersed or introduced in soil, including fruit flies of the genera Anastrepha, Atherigona, Bactrocera, Ceratitis, Rhagoletis and Toxotrypana. Other Diptera include species of Agromyza, Dacus, Delia and Paradiplosis, though some Lepidoptera are also represented, including Prays spp. With Coleoptera, it is the adults that use this pathway, including the Colorado beetle (Leptinotarsa decemlineata) where ‘adults can contaminate almost any bulk material moved in trade’ (CABI, 2009), also the rhinoceros beetle (Oryctes boas), the white grub (Phyllophaga smithi), and any number of other insects including ants (e.g. Solenopsis) and termites.

As a bulk medium, there is the possibility that any of a number of other organisms could be transported, particularly earthworms (annelids), snails (mollusks), flatworms, spiders (arachnids), centipede/millipedes, and even vertebrates such as snakes and lizards (reptiles), frogs and toads (amphibians) and possibly mice or other small mammals.

Principle processes

Solid ballast was a means for long-distance dispersal of a number of now invasive plants. Records include Crupina vulgaris (Sorrie and Somers, 1999), Cytisus scoparius into western North America (Waloff, 1966), Lythrum salicaria into eastern North America either in ship ballast or with sheep wool around 1800 (Stuckey, 1980; Thompson et al., 1987), Chrysanthemoides monilifera into Australia from ship ballast from South Africa onto the banks of the Hunter River around 1908 (Stuart, 2002), Alternanthera philoxeroides arrived in Australia during the 1940s probably in ship ballast (Julien and Broadbent, 1980), and Imperata cylindrica was reportedly introduced into Oregon, USA through ballast in 1971 (Dickens and Buchanan, 1971), though there are no accounts of it establishing there.

Local dispersal of plants once introduced is more commonly recorded, though rarely as the main means of spread. Use of contaminated sand and gravel during road building and maintenance has been cited as a means for the spread of Ageratina adenophora, Cytisus scoparius (Peterson and Prasad, 1998), Imperata cylindrica (Willard 1988; Patterson and McWhorter 1993), Prosopis ruscifolia and Ulex europaeus (CABI, 2009). Fungal pathogens are also known to be dispersed, as in a national park in the USA, continued outbreaks of Phytophthora cinnamomi arose from the distribution of the pathogen with infected road-making gravel, and it remained viable in the gravel for at least 5 years (Weste, 1975).

Use of contaminated building materials in construction was noted for the spread of Senecio jacobaea, Ulex europaeus when mined or quarried from infested riverbeds; Onopordum acanthium achenes were moved long distances in soil and gravel used for construction purposes (Qaderi and Cavers, 2000), and Lycium ferocissimum seeds can be dispersed through contamination of gravel or mud but these are considered of minor importance compared to spread by birds or mammals (Parsons and Cuthbertson, 1992). Also, the transportation of soil, sand and gravel from infested areas for construction purposes may be the reason for the invasion of Parthenium hysterophorus along roadsides and around buildings in Ethiopia (Taye, 2002), and in Queensland, Australia, some sand pits have been quarantined and records of all sand/gravel movements from these sites have to be kept due to the spread of Mimosa diplotricha (Anon., 2001).

The movement of manure has been implicated specifically in the local spread of some invasive plants, e.g. Alopecurus myosuroides. Striga asiatica seeds survive for at least 56 hours during passage through cattle, pigs or horses and could thus be spread following movement of the animals or their manure (Sand and Manley, 1990); this could also be the case for other parasitic weeds. Nishida (2002) attributes invasion of Abutilon theophrasti, Solanum carolinense, Amaranthus spinosus, Rumex obtusifolius and Cirsium vulgare into agricultural land in Japan to application of manure from cattle fed on imported feed contaminated with weed seeds. In addition to plants, the fungal pathogen Streptomyces ipomoeae is often found at old barn sites, and evidence suggests it passes through the digestive systems of cattle and horses and multiplies in the manure. Also, the chafer beetle (Pachnoda interrupta) can be carried from field to field or even further in organic manure.

Some associated substrates are very specific and will be covered here as they would not naturally be included in any other pathway; in this case mushroom-growing substrate and spend mushroom compost. For example, both Pseudomonas agarici and Pseudomonas tolaasii attack production mushrooms and significantly reduce the quality and quantity of the yield, and they are introduced via contaminated substrate and spread to other units via spent compost.

There are other assorted or undetermined examples, including Alternanthera philoxeroides spread in top soil (Gunasekera, 1999), Clidemia hirta may be transported over long distances in soil (Binggeli, 2003), and Solanum elaeagnifolium was introduced into California in 1890 in contaminated ballast and bedding used in railroad cattle (Goeden, 1971). A number of other species are noted as being associated with this pathway but with no further details, including Lantana camara, Limnocharis flava, Pueraria montana var. lobata and Tanacetum vulgare.

Geographical routes and corridors and human-mediated history

All introductions whether long-distance or local, are human-mediated. International introduction via solid ship ballast followed the evolution of global shipping trade and routes, but became much less important during the 1900s when sea water began to become the principal ballast material. Local spread of invasive species has continued nonetheless, mainly from road building and other physical construction activities.

Species Transported by Vector

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SpeciesNotesLong DistanceLocalReferences
Acacia angustissima (prairie acacia)Form persistent seed banks, with viable seeds for over 5 years. Yes Gardiner et al. (2008)
Acacia decurrens (green wattle)Spread in dumped garden waste and contaminated soil Yes Weeds of Australia (2016)
Acacia longifolia (golden wattle)Most seeds stay under canopy. Yes Wilgen et al. (2004)
Acacia mearnsii (black wattle) Yes De Wit et al. (2001)
Acacia saligna (coojong)With sand for construction. Species can produce an enormous seed back which can remain dormant in soil for 5 years Yes Cronk and Fuller (1995); Duke (1983); Cohen et al. (2008)
Acer negundo (box elder) Yes
Achatina fulica (giant African land snail) Yes
Achillea millefolium (yarrow) Yes Sanecki et al. (2003)
Achlysiella williamsi Yes
Acmella uliginosa (marsh para cress)Seeds Yes Yes Chung et al. (2007)
Adenanthera pavonina (red-bead tree)Seeds Yes Yes Orwa et al. (2009)
Adoretus sinicus (Chinese rose beetle)Eggs, larvae or adults in soil of potted plants Yes McQuate and Jameson (2011b)
Aeginetia indica (forest ghost flower)Not mentioned in references but could be a possible way of seed movement Yes
Aeschynomene americana (shyleaf)Seeds Yes Yes Vibrans (2009)
Agave americana (century plant)Seeds, bulbils and stem fragments Yes Yes Weeds of Australia (2016)
Agave sisalana (sisal hemp)Bulbils Yes Yes
Agave vivipara (Caribbean agave)Bulbils Yes PROTA (2015)
Ageratina adenophora (Croftonweed)Contaminant of soil, sand, gravel Yes
Ageratum houstonianum (Blue billygoatweed)Establishes easily in open soil in cultivated land. Yes Johnson (1971)
Agrostis capillaris (common bent) Yes Yes
Agrotis ipsilon (black cutworm)larvae, pupae in soil Yes
Alhagi maurorum (camelthorn)Seeds carried by water Yes
Allamanda cathartica (yellow allamanda)Seeds Yes Francis (2000)
Alocasia cucullata (Chinese taro)Root segments and rhizomes in soil moved by humans Yes Yes PIER (2019)
Alocasia macrorrhizos (giant taro)Corms and tubers Yes Yes
Alopecurus myosuroides (black-grass) Yes
Alpinia purpurata (red ginger)Rhizomes Yes Yes Acevedo-Rodríguez and Strong (2005)
Alternanthera halimifolia (hairy joyweed)Seeds Yes Yes
Alternanthera philoxeroides (alligator weed)Mulching materials, top soil Yes
Alysicarpus vaginalis (alyce clover) Yes Yes Duke (1981); Flora of China Editorial Committee (2014); Hanelt et al. (2001); Quattrocchi (2012)
Alyssum desertorum (desert madwort) Yes Yes Olliff et al. (2001)
Amaranthus palmeri (Palmer amaranth)From agricultural practices Yes Ward et al. (2013)
Ambrosia artemisiifolia (common ragweed)Soil, sand Yes Yes
Ambrosia psilostachya (perennial ragweed)Soil, sand Yes
Ambrosia tenuifolia (lacy ragweed)Seeds and roots Yes Yes Montagnani et al. (2017)
Ambrosia trifida (giant ragweed) Yes Yes
Amynthas agrestis (crazy worm)All stages possible in soil Yes Yes Gates (1953; 1954; 1958)
Anastrepha fraterculus (South American fruit fly)Risk of puparia in soil. Yes
Anastrepha ludens (Mexican fruit fly)Risk of puparia in soil. Yes
Anastrepha manihoti (cassava fruit fly)Risk of puparia if in soil. Yes
Anastrepha obliqua (West Indian fruit fly)Risk of puparia in soil. Yes
Anastrepha striata (guava fruit fly)Risk of puparia in soil. Yes
Anastrepha suspensa (Caribbean fruit fly)Risk of puparia in soil. Yes
Andropogon glomeratus (bushy bluestem)Seeds can be transported together with imported soil and gravel Yes Yes PIER (2008)
Anguina agrostis (nematode, bentgrass)Turf and grass seeds Yes
Anguina tritici (wheat seed gall nematode)Rehydrated galls, juveniles Yes
Annona reticulata (bullock's heart) Yes Yes Janick and Paull (2008); Morton (1987)
Anoplolepis gracilipes (yellow crazy ant) Yes Yes
Anthemis cotula (dog fennel) Yes
Aphasmatylenchus straturatus Yes
Aphelenchoides arachidis (groundnut testa nematode)From peanut fields Yes
Aphelenchoides besseyi (rice leaf nematode) Yes
Aphelenchoides fragariae (strawberry crimp nematode) Yes
Aphelenchoides ritzemabosi (Chrysanthemum foliar eelworm)With flowers and cuttings Yes
Argemone mexicana (Mexican poppy) Yes Yes
Aristolochia elegans (elegant Dutchman’s pipe) Yes Randall (2012); Starr et al. (2003)
Arkoola nigra (black leaf blight of soybean)infested soil Yes Moore et al. (2006)
Arthurdendyus triangulatus (New Zealand flatworm)Local movement of topsoil and dung can facilitate flatworm spread Yes Murchie et al. (2003)
Arundo donax (giant reed)Seeds, plant fragments Yes Yes USDA-NRCS (2014)
Asparagus asparagoides (bridal creeper) Yes Parsons and Cuthbertson (2001)
Asparagus falcatus (sicklethorn)Escaped from cultivation Yes NSW Weedwise (2018)
Atherigona naqvii (shootfly)Eggs might be moved with soil. Yes
Atherigona oryzae (rice shoot fly)Some risk from puparia in soil. Yes
Azolla filiculoides (water fern)Rivers Yes
Bactrocera carambolae (carambola fruit fly)Risk of puparia in soil. Yes
Bactrocera cucumis (cucumber fruit fly)Risk of puparia in soil Yes
Bactrocera cucurbitae (melon fly)Most frequently pupae Yes Yes
Bactrocera dorsalis (Oriental fruit fly)Pupae Yes Yes
Bactrocera facialisRisk of puparia in soil. Yes
Bactrocera frauenfeldi (mango fruit fly)Risk of puparia in soil. Yes
Bactrocera jarvisi (Jarvis' fruit fly)Risk of puparia in soil. Yes
Bactrocera kirkiRisk of puparia in soil. Yes
Bactrocera latifrons (Solanum fruit fly)Risk of puparia in soil. Yes
Bactrocera melanotusRisk of puparia in soil. Yes
Bactrocera minax (Chinese citrus fly)Possible risk of puparia in soil Yes
Bactrocera neohumeralisRisk of puparia in soil. Yes
Bactrocera occipitalisRisk of puparia in soil. Yes
Bactrocera oleae (olive fruit fly)Risk of puparia in soil. Yes
Bactrocera passiflorae (Fijian fruit fly)Risk of puparia in soil. Yes
Bactrocera psidii (South Sea guava fruit fly)Risk of puparia in soil. Yes
Bactrocera tauRisk of puparia in soil. Yes
Bactrocera tryoni (Queensland fruit fly)Risk of puparia in soil. Yes
Bactrocera tsuneonis (Japanese orange fly)Risk of puparia in soil Yes
Bactrocera umbrosaRisk of puparia in soil. Yes
Bactrocera xanthodes (Pacific fruit fly)Risk of puparia in soil Yes
Bactrocera zonata (peach fruit fly)Pupae Yes Yes
Bambusa bambos (giant thorny bamboo)Seeds, rhizomes and cuttings Yes Yes Duriyaprapan and Jansen (1995)
Basella alba (malabar spinach)Possibly in waste associated with its cultivation and consumption Yes Dave's Garden (2017)
Bauhinia monandra (Napoleon's plume)Seeds Yes Yes Queensland Department of Primary Industries and Fisheries (2011)
Bauhinia purpurea (purple bauhinia)Seeds Yes Yes Orwa et al. (2009)
Bauhinia tomentosa (yellow bauhinia)Seeds Yes Yes PROTA (2015)
Bauhinia variegata (mountain ebony)Seeds Yes Yes Smith (2010)
Belonolaimus longicaudatus (sting nematode) Yes
Berberis thunbergii (Japanese barberry)Unintentional transport of seeds Yes
Bergia capensis (white water fire)Possible from rice cultivation Yes
Bidens pilosa (blackjack)Seed as contaminant Yes Yes Sankaran and Suresh (2013)
blood disease bacterium (blood disease bacterium of banana)Water. Yes
Bocconia frutescens (plume poppy)Contaminated soil should not be moved from invaded areas Yes Benitez and Saulibio (2007)
Bontia daphnoides (white alling)Seeds might be dispersed in soil used in cultivation Yes
Bothriochloa bladhii (Caucasian bluestem)Seeds Yes Yes Cook et al. (2005)
Bothriochloa pertusa (pitted beard grass)Contaminant Yes
Botryotinia fuckeliana (grey mould-rot)Sclerotia in agricultural soils. Yes
Brassica nigra (black mustard)Via seed Yes Yes Cal-IPC (California Invasive Plant Council) (2004)
Brassica rapa (field mustard)Possible from its cultivation Yes
Breynia disticha (snowbush)Possible from its ornamental use Yes Yes
Bromus tectorum (downy brome)Top soil, mine and construction spoils Yes
Buddleja davidii (butterfly bush) Yes
Bunias orientalis (Turkish warty-cabbage) Yes Yes
Bursaphelenchus xylophilus (pine wilt nematode) Yes
Callisia repens (creeping inch-plant)Plants and plant segments Yes Yes Acevedo-Rodríguez and Strong (2005)
Calopogonium mucunoides (calopo)Seeds Yes Yes Cook et al. (2005)
Calotropis procera (apple of sodom) Yes
Canna indica (canna lilly) Yes
Capsicum annuum (bell pepper) Yes Basu and De (2003)
Carcinus maenas (European shore crab)Possible if marine sediments are those such as found in ballast tanks Yes Yes Klassen and Locke (2007)
Cardamine flexuosa (wavy bittercress)Seeds as contaminant Yes Yes ISSG (2019)
Cardiospermum grandiflorum (balloon vine)Seeds, root fragments Yes Weeds of Australia (2015)
Carduus nutans (nodding thistle)Ship ballast (1800s) Yes
Carnation mottle virus (mottle of carnation) Yes
Carpobrotus chilensis (sea fig)As escaping from cultivation Yes Jonkers (2001)
Cassia fistula (Indian laburnum) Yes Yes Bosch (2007); Duke (1983); Hanelt et al. (2001); PIER (2014)
Cassytha filiformis (love-vine)Soil collected from the vicinity of C. filiformis-infected plants can be contaminated with seeds Yes Yes Nelson (2008)
Catharanthus roseus (Madagascar periwinkle) Yes Yes PROTA (2015)
Cenchrus ciliaris (Buffel grass) Yes Yes
Centaurea debeauxii (meadow knapweed) Yes Yes
Centaurea diffusa (diffuse knapweed) Yes
Centaurea melitensis (Maltese starthistle) Yes DiTomaso and Healy (2007)
Centaurea stoebe subsp. micranthos (spotted knapweed) Yes
Ceratitis capitata (Mediterranean fruit fly)Risk of puparia in soil. Yes
Ceratitis cosyra (mango fruit fly)Risk of puparia in soil Yes Yes
Ceratitis punctata (cacao fruit fly)Risk of puparia in soil Yes
Ceratitis quinaria (five-spotted fruit fly)Risk of puparia in soil. Yes
Ceratitis rosa (Natal fruit fly)Not reported but possible if soil contains puparia Yes Yes White and Elson-Harris (1994)
Ceratocystis fimbriata (Ceratocystis blight)Water from infested soil. Yes
Ceratocystis platani (canker stain of plane)Infested soil, river water Yes Yes
Cestrum nocturnum (night jessamine)Species may be transported by soil or water drained from areas where it is cultivated Yes Yes
Chloris gayana (Rhodes grass)Seeds as contaminants Yes Yes Weeds of Australia (2020)
Chloris virgata (feather finger grass)Seed contaminants Yes Yes PIER (2015)
Chromolaena odorata (Siam weed)Assumed as possible means Yes Yes
Chrysanthemoides monilifera (boneseed) Yes
Cinnamomum burmanni (padang cassia) Yes Yes
Cinnamomum camphora (camphor laurel)Water Yes
Cirsium arvense (creeping thistle) Yes
Cirsium mexicanum (Mexican thistle)Seed Yes Yes Holm et al. (1997)
Cirsium vulgare (spear thistle)Water Yes
Clavibacter michiganensis (bacterial canker of tomato) Yes
Clavibacter sepedonicus (potato ring rot)Transfer of tubers. Yes Yes
Clematis vitalba (old man's beard)Water Yes
Cleome rutidosperma (fringed spiderflower)Seed contaminant Yes Yes PIER (2014)
Clerodendrum bungei (rose glorybower)Can spread by portions of roots within contaminated soil Yes Yes
Clerodendrum chinense (Chinese glory bower) Yes Yes PIER (2012)
Clerodendrum indicum (Turk's turban) Yes Yes
Clerodendrum quadriloculare (bronze-leaved clerodendrum) Yes Yes PIER (2012)
Clerodendrum speciosissimum (Java glory bower)Rhizome fragments may be accidentally transported in soil stuck to machinery, vehicles, etc Yes Yes
Clerodendrum thomsoniae (bleeding glory bower)Propagated by root cuttings and could spread in transported ssoil Yes Yes
Clidemia hirta (Koster's curse) Yes Yes Binggeli (2003)
Cnidoscolus aconitifolius (chaya)Possible, if cuttings are able to root and in the rare event of cultivated plants producing seeds Yes
Colocasia esculenta (taro)Soil movements can disperse buried corms Yes Yes Safo-Kantaka (2004)
Coniothyrium glycines (red leaf blotch) Yes Hartman et al. (1987)
Conyza bonariensis (hairy fleabane) Yes
Conyza canadensis (Canadian fleabane)Seeds in potting compost. Yes
Conyza sumatrensis (tall fleabane)Seeds in potting compost Yes
Coptotermes gestroi (Asian subterranean termite)Alates, larvae or nymphs in moist soil Yes Yes Hapukotuwa and Kenneth (2012)
Corbicula fluminea (Asian clam) Yes
Coriandrum sativum (coriander) Yes Randall (2012)
Cornu aspersum (common garden snail) Yes Yes
Crassostrea virginica (eastern oyster) Yes
Crepidula fornicata (American slipper limpet)It is one possibility between America and Europe Yes
Crescentia cujete (calabash tree)No information available but possible from its various uses Yes
Cronartium ribicola (white pine blister rust)Aeciospores Yes
Crotalaria maypurensis (rattlebox weed)Seeds Yes Yes Gómez-Sosa (2000)
Crotalaria spectabilis (showy rattlepod)Seeds as contaminant in soil Yes Yes Maddox et al. (2011)
Croton argenteus (silver July croton)Seeds as contaminant in dried and wet mud Yes Yes Standley and Steyermark (1946)
Crupina vulgaris (bearded creeper)Ballast. Yes
Cryptostegia grandiflora (rubber vine) Yes
Cryptostegia madagascariensis (Madagascar rubbervine) Yes Yes PIER (2012)
Cuphea carthagenensis (Colombian waxweed) Yes Technigro (2011)
Cupressus sempervirens (Mediterranean cypress)Seeds Yes Yes
Cyanthillium cinereum (little ironweed)Seeds Yes Yes Holm et al. (1997)
Cyclosorus parasiticus (parasitic maiden fern)Likely mode of spore dispersal Yes Yes
Cynodon nlemfuensis (African Bermuda-grass)Seeds Yes Yes Cook et al. (2005)
Cynodon plectostachyus (African stargrass)Seeds and stolons Yes Cook et al. (2005)
Cynoglossum officinale (hound's tongue)seeds Yes
Cyperus difformis (small-flowered nutsedge)As a contaminant of soils Yes Yes Holm et al. (1979)
Cyperus imbricatus (shingle flatsedge)Seeds and stem segments Yes Yes Queensland Department of Primary Industries and Fisheries (2011)
Cyperus rotundus (purple nutsedge)Soil attached to the roots of transplanted material, e.g. tree nursery stock Yes
Cytisus scoparius (Scotch broom)River sand carrying seeds. Yes Yes Peterson and Raj Prasad (1998)
Dactyloctenium aegyptium (crowfoot grass)Seeds Yes Yes Holm et al. (1977)
Datura metel (Hindu datura)Can be transported via soil attached to clothing, vehicles, machinery, etc. Yes Yes PIER (2014)
Delia antiqua (onion fly)Soil from infected crop. Yes
Delia coarctata (fly, wheat bulb)Infected growing medium. Yes
Delia floralis (turnip maggot)Infected growing medium. Yes
Delia platura (bean seed fly)Infected growing medium and seedlings and rotting plant material. Yes
Delia radicum (cabbage root fly)Infected growing medium. Yes
Dendroctonus valens (red turpentine beetle)Soil Yes
Desmodium cajanifolium (tropical tick trefoil)No information available but possible from its cultivation Yes
Desmostachya bipinnata (halfa grass) Yes
Dichanthium annulatum (Kleberg's bluestem)Seeds Yes Yes Vibrans (2011)
Dichanthium aristatum (angelton bluestem)Possible due to its cultivation for pasture and hay Yes
Dickeya zeae (bacterial stalk rot of maize)
Digitaria bicornis (Asian crabgrass) Yes Yes
Digitaria ciliaris (southern crabgrass)Seeds, plant segments, rhizomes Yes Yes Holm et al. (1979)
Digitaria sanguinalis (large crabgrass) Yes
Dioscorea alata (white yam)Tubers (yams) and bulbils Yes Yes Langeland et al. (2008)
Diplazium esculentum (vegetable fern)Although no information available, it is possible as it is used as an ornamental Yes
Diprion similis (white pine sawfly)Soil; litter Yes
Discus rotundatus (rotund disc)Not explicitly mentioned in literature, but likely based on the species’ biology Yes
Ditylenchus angustus (rice stem nematode) Yes
Ditylenchus destructor (potato tuber nematode) Yes
Ditylenchus dipsaci (stem and bulb nematode) Yes
Drymaria cordata (tropical chickweed)Seeds and plant fragments Yes Yes USDA-ARS (2014)
Dysphania ambrosioides (Mexican tea)Seeds Yes Yes USDA-ARS (2013)
Echinochloa crus-galli (barnyard grass)Seeds Yes Yes
Echinocystis lobata (wild cucumber) Yes Yes
Echium plantagineum (Paterson's curse)River sand Yes
Egeria densa (leafy elodea)Water Yes
Ehrharta erecta (panic veldtgrass) Yes Ogle (1988)
Emex australis (Doublegee) Yes
Emex spinosa (spiny emex)Transport possible in soil but no documented incidences. Yes
Emilia coccinea (scarlet tasselflower)Seeds Yes Yes Davidse et al. (2018)
Emilia fosbergii (Florida tassel-flower)Seeds Yes Yes Vibrans (2011)
Emilia praetermissa (yellow thistle)Seeds dispersed as contaminants in soils Yes Yes PROTA (2020)
Eragrostis amabilis (Japanese lovegrass)Seeds Yes Whistler (1995)
Eragrostis lehmanniana (Lehmann lovegrass)Seeds may be present in soil, gravel etc being used in rangeland maintenance Yes Yes
Eremochloa ophiuroides (centipedegrass)Seeds and stolons Yes Yes Brosnan and Deputy (2008)
Erigeron bellioides (bellorita)Seed as contaminant in soil Yes Yes Nagata (1995)
Eucalyptus robusta (swamp mahogany)Seed Yes Orwa et al. (2009)
Euphorbia esula (leafy spurge)Moving, excavating equipment. Yes
Fallopia japonica (Japanese knotweed)Topsoil movement Yes
Fallopia sachalinensis (giant knotweed)Contamination by rhizome Yes
Fallopia x bohemicamovement of soil Yes
Ficus pumila (creeping fig)Can reproduce by vegetative fragmentation Yes Yes
Fimbristylis cymosa (tropical fimbry) Yes Yes
Fimbristylis littoralis (lesser fimbristylis)Seeds Yes Yes Holm et al. (1977)
Forficula auricularia (European earwig)frequent and important pathway for this species; nymphs and adults Yes Yes
Fumaria muralis (common ramping-fumitory) Yes Western Australian Herbarium (1998)
Fusarium oxysporum f.sp. medicaginis (fusarium wilt of alfalfa) Yes Yes
Fusarium oxysporum f.sp. niveum (Fusarium wilt of watermelon)possible, chlamydospores Yes Nishimura; 1971; Wang et al.; 1993
Fusarium oxysporum f.sp. radicis-lycopersici (Fusarium crown rot)Mycelium, chlamydospores Yes
Galinsoga parviflora (gallant soldier)Seeds as contaminants Yes Yes Damalas (2008)
Galinsoga quadriradiata (shaggy soldier)Seeds as a contaminant Yes Yes Kabuce and Priede (2010)
Genista monspessulana (Montpellier broom)river sand Yes
Gilpinia hercyniae (spruce sawfly)Soil Yes
Globodera pallida (white potato cyst nematode)Cysts in water and dust storm Yes Yes Been and Schomaker (2006)
Globodera rostochiensis (yellow potato cyst nematode)Cysts in soil and dust storms, juveniles Yes Yes
Globodera tabacum (tobacco cyst nematode)Cysts in soil, water also blown by wind Yes
Glomerella tucumanensis (red rot of sugarcane)Conidia or other fungal structures may be carried long distances by rain/flood water. Yes
Golovinomyces cichoracearum (powdery mildew) Yes
Golovinomyces orontii (powdery mildew) Yes
Gomphocarpus physocarpus (balloon cotton bush)Fruits, seeds, and stem fragments Yes Yes Motooka et al. (2003)
Gonipterus gibberus (snout beetle, eucalyptus)Larvae, pupa Yes
Gonipterus scutellatus (eucalyptus snout beetle)Larvae, pupa Yes
Haematoxylum campechianum (logwood) Yes Yes Gurib-Fakim (2005)
Hedera helix (ivy) Yes
Helenium amarum (bitterweed) Yes Tomley and Panetta (2002)
Helianthus tuberosus (Jerusalem artichoke) Yes Yes Kompała-Bąba and Błońska (2008)
Helicotylenchus dihystera (common spiral nematode)With plants and soil Yes
Helicotylenchus multicinctus (banana spiral nematode)With banana rhizones Yes
Helicotylenchus oleae (spiral nematode)With host plants Yes
Helicotylenchus pseudorobustus (spiral nematode)With soil Yes
Helicotylenchus variocaudatus Yes
Heliotropium curassavicum (salt heliotrope)Seeds, root fragments Yes Yes Hegazy et al. (1994)
Hemicriconemoides mangiferae Yes
Hemicycliophora arenaria (sheath nematode) Yes
Heracleum mantegazzianum (giant hogweed) Yes Tiley et al. (1996)
Heterodera avenae (cereal cyst eelworm)Cysts in soil. Yes
Heterodera cajani (pigeon pea cyst nematode)Cysts Yes
Heterodera ciceri (chickpea cyst nematode)As cysts. Yes
Heterodera glycines (soybean cyst nematode)Cysts in soil. Yes
Heterodera goettingiana (pea cyst eelworm)Cysts as contaminants. Yes
Heterodera oryzae (rice cyst nematode)Cysts in soil Yes
Heterodera oryzicola (rice cyst nematode)Cysts in soil. Yes
Heterodera sacchari (sugarcane cyst nematode)Cysts in soil. Yes
Heterodera zeae (corn cyst nematode)Cysts as contaminants. Yes
Heterotheca grandiflora (telegraph weed) Yes Yes DiTomaso and Healy (2007); PIER (2015)
Heterotis rotundifolia (pink lady)Seeds Yes Yes Prota4U (2013)
Hirschmanniella miticausa Yes
Hirschmanniella oryzae (rice root nematode) Yes
Hirschmanniella spinicaudata (rice root nematode) Yes
Hoplolaimus indicus (lance nematode) Yes
Hoplolaimus pararobustus (lance nematode)With soil. Yes
Hoplolaimus seinhorsti (lance nematode) Yes
Hymenachne amplexicaulis (hymenachne)Substrate contaminating gear, equipment, machinery, vehicles Yes Yes Australian Weeds Committee (2012)
Hyparrhenia rufa (Jaragua grass)Seeds Yes Yes Starr et al. (2003)
Hyptis alata (clustered bushmint)Seeds as contaminants
Impatiens balsamina (garden balsam)Seeds Yes Yes van Valkenburg and Bunyapraphatsara (2001)
Impatiens glandulifera (Himalayan balsam) Yes Beerling and Perrins (1993); Hartmann et al. (1995)
Impatiens parviflora (small balsam) Yes Coombe (1956)
Impatiens walleriana (busy lizzy)Seeds Yes Yes Queensland Government (2018)
Imperata cylindrica (cogon grass)Soil attached to the roots of transplanted material, e.g. tree nursery stock Yes
Indigofera hirsuta (hairy indigo) Yes Yes Duke (1981)
Indigofera spicata (creeping indigo)Soil transported may contain seeds Yes Yes Morton (1989)
Indigofera tinctoria (true indigo) Yes Yes
Indigofera trita (Asian indigo)Seeds Yes Yes PROTA (2014)
Indigofera trita subsp. scabra (Asian Indigo)Seeds Yes Yes PROTA (2014)
Ipomoea hederifolia (scarlet-creeper )Seeds Yes Queensland Government (2016)
Ipomoea purpurea (tall morning glory)Potential seed contaminant Yes Yes USDA-ARS (2014)
Iris domestica (blackberry lily)Possible, from its cultivation Yes
Ischaemum rugosum (saramollagrass)Seed contaminant Yes Yes PIER (2015)
Iva xanthiifolia (marsh-elder) Yes Yes Follak (2014)
Jasminum fluminense (Brazilian jasmine)Seeds Yes Yes Francis (2004)
Jasminum simplicifolium (Australian wax jasmine)Possible from its cultivation Yes
Jatropha curcas (jatropha) Yes Pitt (1999)
Jatropha gossypiifolia (bellyache bush)Sand mining Yes
Jatropha integerrima (peregrina)Possible, as it is listed as escaped from cultivation Yes Flora of North America Editorial Committee (2020)
Juncus effusus (common rush) Yes
Juncus ensifolius (swordleaf rush) Yes NZPCN (New Zealand Plant Conservation Network) (2015)
Kalanchoe delagoensis (chandelier plant)Seeds, plantlets, plant fragments Yes Yes BioNET-EAFRINET (2011)
Kalanchoe pinnata (cathedral bells) Yes
Lamium amplexicaule (henbit deadnettle)Rivers and floods Yes
Lantana camara (lantana) Yes Yes
Lasius neglectus (invasive garden ant) Yes Yes
Lepidium draba (hoary cress) Yes
Lepidium latifolium (perennial pepperweed) Yes Yes Halvorsen and Grøstad (1998)
Lepidium virginicum (Virginian peppercress)In garden soil used for compost. Yes Dave’s Garden (2016)
Leptinotarsa decemlineata (Colorado potato beetle)Adults can contaminate almost any bulk material moved in trade Yes
Leucanthemum vulgare (oxeye daisy) Yes
Ligustrum japonicum (Japanese privet)Possible from its cultivation although no details available Yes
Limax maximus (leopard slug)Not uncommon Yes Yes
Limnocharis flava (yellow bur-head) Yes
Limnoperna fortunei (golden mussel)Sandy trucks that transport artificial beaches Yes Belz (2006)
Lindernia crustacea (Malaysian false pimpernel)Seeds and stem fragments Yes Yes Holm et al. (1979)
Linepithema humile (Argentine ant) Yes Yes
Liriomyza bryoniae (tomato leaf miner)Road transport. Yes
Longidorus elongatus (needle nematode) Yes
Lumbricus rubellus Yes Yes
Lumbricus terrestris Yes Yes
Lupinus angustifolius (narrow-leaf lupin)Seeds Yes Yes USDA-NRCS (2017)
Lupinus polyphyllus (garden lupin)Seeds Yes Yes NOBANIS (2015)
Lygodium flexuosum (maidenhair creeper)No information available but it could be a possibility as it is used as an ornamental Yes USDA-APHIS-PPQ (2009)
Lygodium microphyllum (old world climbing fern) Yes
Lythrum salicaria (purple loosestrife)Ship ballast; ship transport Yes Yes Thompson et al. (1987)
Malva pusilla (round-leaved mallow)Seed contaminant Yes Yes Makowski and Morrison (1989)
Malvaviscus arboreus (wax mallow)Seeds Yes Yes Webb et al. (1988)
Melilotus officinalis (yellow sweet clover) Yes Yes
Melinis minutiflora (molasses grass) Yes
Meloidogyne acronea (African cotton root nematode)Eggs and galls in soil. Yes
Meloidogyne arenaria (peanut root-knot nematode)Eggs and galls in soil. Yes
Meloidogyne brevicauda (Indian root-knot nematode)Soil Yes
Meloidogyne chitwoodi (columbia root-knot nematode)Eggs in soil. Yes
Meloidogyne coffeicola (coffee root-knot nematode) Yes
Meloidogyne decalineata (African coffee root-knot nematode)Eggs and juveniles in soil. Yes
Meloidogyne exigua (coffee root-knot nematode)Eggs and juveniles in soil. Yes
Meloidogyne fallax (false Columbia root-knot nematode)Eggs and juveniles in soil. Yes
Meloidogyne graminicola (rice root knot nematode)Eggs and juveniles in soil. Yes
Meloidogyne hapla (root knot nematode)Eggs and juveniles in soil. Yes
Meloidogyne incognita (root-knot nematode)Eggs and galls in soil. Movement of infested soil. Yes Yes
Meloidogyne javanica (sugarcane eelworm)Eggs and galls in soil. Yes
Meloidogyne mayaguensisEggs and galls in soil. Yes
Mesosphaerum pectinatum (comb bushmint) Yes Yes
Miconia calvescens (miconia)Seeds Yes Yes
Microdochium panattonianum (anthracnose (of lettuce))Soil from anthracnose-infected lettuce fields. Yes
Mikania micrantha (bitter vine) Yes Yes
Mimosa arenosa (elegant mimosa)Seeds Yes Yes Francis (2004)
Mimosa diplotricha (giant sensitive plant) Yes DAF (2016); Parsons and Cuthbertson (1992)
Mimosa pudica (sensitive plant) Yes
Mirabilis jalapa (four o'clock flower)Seeds might spread through soil waste from its cultivation. Yes
Monilochaetes infuscans (scurf of sweet potato) Yes
Moringa oleifera (horse radish tree)Soil debris from cultivation Yes Csurhes and Navie (2016)
Muntingia calabura (Jamaica cherry)Probably arrived to Seychelles with soil machinery Yes Gerlach (1996)
Murdannia nudiflora (doveweed)Soil and water. Yes
Murraya paniculata (orange jessamine)Dispersed in dumped garden waste Yes Brisbane City Council (2020)
Mycosphaerella gibsonii (needle blight of pine)Mycorrhizal soil inocula Yes
Nacobbus aberrans (false root-knot nematode)Eggs and adults as contaminants. Yes
Nassella trichotoma (serrated tussock grass) Yes
Nelsonia canescens (blue pussyleaf)Seeds and roots Yes Yes Mahbubur (2013)
Neodiprion sertifer (European pine sawfly)Soil. Yes
Nephrolepis hirsutula (sword fern)Possible from its use as mulch Yes Whistler (1988)
Nerium oleander (oleander)Possible from its use as an ornamental Yes
Neyraudia reynaudiana (burma reed) Yes Rasha (2005)
Nicotiana plumbaginifolia (Tex-Mex tobacco) Yes
Nopalea cochenillifera (cochineal cactus)Can be spread through garden waste Yes PIER (2017)
Ocimum gratissimum (African basil)Seed, stem fragment in garden waste Yes Yes PROSEA (2018)
Odontonema cuspidatum (Cardinal’s guard)Pieces of stems and roots from gardens Yes Yes Francis (2005)
Oldenlandia corymbosa (flat-top mille graines)Seeds, roots, stem fragments Yes Yes PROSEA (2018)
Oldenlandia lancifolia (calycose mille graines)Seeds as contaminant Yes Yes Pringle (1982)
Onopordum acanthium (scotch thistle)Water Yes
Orobanche cernua (nodding broomrape) Yes
Orobanche cumana (sunflower broomrape) Yes
Orobanche ramosa (branched broomrape) Yes Jacobsohn (1984)
Oryctes boas (rhinoceros beetle) Yes
Osteopilus septentrionalis (Cuban treefrog) Yes Yes Perry et al (2006)
Pachnoda interrupta (chafer beetle)Eggs, pupae, quiescent adults Yes
Papuana huebneri (taro beetle) Yes Yes
Paradiplosis tumifex (balsam gall midge)Pupae Yes
Paralongidorus australis (needle nematode) Yes
Paratrichodorus minor (stubby root nematode) Yes
Paratrichodorus porosus Yes
Parthenium hysterophorus (parthenium weed)Soil, sand, irrigation water, flood Yes Shabbir et al. (2011); Taye (2002)
Paspalum dilatatum (dallisgrass)seeds possibly dispersed in soil debris from cultivation Yes
Paspalum paniculatum (Russell River grass)Seeds Yes Yes USDA-ARS (2016)
Paspalum scrobiculatum (ricegrass paspalum) Yes
Paspalum urvillei (Vasey grass)Possibly from agricultural practices Yes Hitchcock (1936); FAO (2012b)
Pastinaca sativa (parsnip)Seeds frequently dispersed with soil movement Yes Yes Cain et al. (2010)
Pectobacterium brasiliense (soft rot and blackleg of ornamentals and potato) Yes Yes
Pegomya hyoscyami (mangold fly)Puparia in soil. Yes
Pelargonium peltatum (ivy geranium)Pelargonium spp. can disperse their small seeds by wind, water, and soil. Yes Dixon (2011); Western Australian Herbarium (2014)
Pelargonium zonale (horseshoe pelargonium)Members of the Pelargonium genus can disperse their small seeds by wind, water, and soil. Yes Yes Dixon (2011); Western Australian Herbarium (2014)
Pennisetum pedicellatum (deenanath grass) Yes
Pennisetum purpureum (elephant grass)Seed and plant segments Yes Yes Queensland Department of Primary Industries and Fisheries (2011)
Pentas lanceolata (Egyptian starcluster)Seeds Yes Yes PROTA (2018)
Pepino mosaic virusDrainage water. Yes
Peronosclerospora philippinensis (Philippine downy mildew of maize)Oospores which are rarely produced serve as survival structures of the pathogen in the soil. Yes USDA (2013)
Persicaria maculosa (redshank)Rivers and floods Yes
Persicaria wallichii (Himalayan knotweed) Yes
Petiveria alliacea (guinea hen weed)Seeds Yes Yes Vibrans (2009)
Petrea volubilis (queen's wreath)Possible. No details but reported as naturalized in Madeira Yes DAISIE (2019)
Phaeoacremonium aleophilum (Petri disease) Yes
Pheidole megacephala (big-headed ant) Yes
Phyllanthus urinaria (leafflower)Soil and water. Yes
Phyllophaga smithi (white grub) Yes
Phytophthora alni species complex (alder Phytophthora)Not specifically demonstrated for the alder Phytophthora but known to be important for root phytophthoras Yes Webber and Rose (2008)
Phytophthora austrocedriDNA of P. austrocedri detected in soil at infected sites Yes Yes Elliot et al. (2015)
Phytophthora boehmeriae (ramie leaf spot) Yes
Phytophthora cinnamomi (Phytophthora dieback)Very common Yes Batini (1977); Colquhoun and Petersen (1994)
Phytophthora drechsleri f.sp. cajani (Phytophthora blight)Mycelium, zoospore Yes
Phytophthora kernoviaeSoil associated with nursery stock Yes Yes EPPO (2013)
Phytophthora lateralis (Port-Orford-cedar root disease) Yes Yes USDA (2003)
Phytophthora medicaginis (Phytophthora root rot of lucerne) Yes
Phytophthora megasperma (root rot)Potting mixes, irrigation water. Yes
Phytophthora porri (white tip of leek)Oospores. Yes
Phytophthora ramorum (Sudden Oak Death (SOD)) Yes
Phytophthora vignae (Phytophthora stem rot of cowpea)water Yes
Pilosella aurantiaca (orange hawkweed)Soil contamination, garden waste Yes
Pilosella officinarum (mouse-ear hawkweed)Soil, garden dumpings Yes
Pityogenes chalcographus (sixtoothed spruce bark beetls)Soil Yes
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)
Platydemus manokwari (New guinea flatworm)P. manokwari can be readily transported in soil on potted plants Yes Yes
Plectranthus scutellarioides (coleus)Garden soil where species is cultivated could be contaminated with cuttings or seeds Yes Yes Missouri Botanical Garden (2014b); Wagner et al. (1999)
Plutella xylostella (diamondback moth) Yes
Poa annua (annual meadowgrass)Seed Yes Yes Holm et al. (1997)
Pomacea canaliculata (golden apple snail) Yes
Portulaca pilosa (kiss-me-quick) Yes Yes
Portulaca quadrifida (chickenweed) Yes
Potato mop-top virus (potato mop-top)Soil from field where virus is endemic Yes
Pratylenchus brachyurus (root-lesion nematode) Yes
Pratylenchus coffeae (banana root nematode) Yes
Pratylenchus goodeyi (banana lesion nematode)From banana orchards. Yes
Pratylenchus loosi (root lesion nematode) Yes
Pratylenchus penetrans (nematode, northern root lesion) Yes
Pratylenchus thornei Yes
Pratylenchus vulnus (walnut root lesion nematode) Yes
Pratylenchus zeae (root lesion nematode) Yes
Prays citri (citrus flower moth) Yes
Pristiphora erichsonii (larch sawfly)Soil Yes
Prosopis pallida (mesquite)Oceanic dispersal Yes
Prosopis ruscifolia Yes
Prosopis velutina (velvet mesquite) Yes
Pseudomonas agarici (drippy gill)Waste casings. Yes
Pseudomonas syringae pv. oryzae (halo blight) Yes
Pseudomonas tolaasii (bacterial blotch of mushroom)Risk in waste casings. Yes
Pseudoperonospora cannabina (downy mildew of hemp)Heavy soils Yes
Psila rosae (carrot root fly)Infected soil is a risk. Yes
Pteris multifida (spider brake)Although not reported it is a possibility as a result of its cultivation Yes
Pteris tripartita (giant brake)Not mentioned in literature, but a possibility from its cultivation Yes
Pteris vittata (Chinese ladder brake fern)Possible, as it is reported as an ornamental Yes Flora of North America Editorial Committee (2019)
Ptychosperma elegans (solitaire palm)Possible in soil debris associated with its cultivation Yes
Puccinia asparagi (asparagus rust) Yes
Pueraria montana var. lobata (kudzu) Yes
Pueraria phaseoloides (tropical kudzu) Yes Yes Cook et al. (2005)
Punctodera chalcoensis Yes
Punctodera punctata (grass cyst nematode) Yes
Pyracantha coccinea (scarlet firethorn)Seeds could be dispersed in soil debris associated with its cultivation. Yes California Invasive Plant Council (2017)
Radopholus citri Yes
Radopholus similis (burrowing nematode) Yes
Ralstonia solanacearum (bacterial wilt of potato)Water. Yes Yes
Rhagoletis cerasi (European cherry fruit fly)Risk of puparia in soil. Yes
Rhagoletis cingulata (cherry fruit fly)Risk of puparia in soil. Yes
Rhagoletis completa (walnut husk fly)Risk of puparia in soil. Yes
Rhagoletis fausta (black cherry fruit fly)Risk of puparia in soil. Yes
Rhagoletis indifferens (western cherry fruit fly)Risk of puparia in soil. Yes
Rhagoletis mendax (blueberry fruit fly)Risk of puparia in soil. Yes
Rhagoletis pomonella (apple maggot)Risk of puparia in soil. Yes
Rhagoletis ribicola (American currant fruit fly)Risk of puparia in soil. Yes
Rhizobium radiobacter (crown gall) Yes
Rottboellia cochinchinensis (itch grass)Road construction aggregate in Louisiana Yes Millhollon (1980)
Rotylenchulus parvus (reniform nematode) Yes
Rotylenchulus reniformis (reniform nematode) Yes
Rubus fruticosus (blackberry)Unintentional transport of seeds Yes
Rubus parviflorus (thimbleberry)Seeds, root fragments Yes Haeussler et al. (1990)
Rumex obtusifolius (broad-leaved dock)Rivers Yes
Salvia splendens (scarlet sage) Yes Yes Floridata (2014); Liogier and Martorell (2000)
Scaevola taccada (beach naupaka)Fruits, cuttings Yes Yes ISSG (2012)
Schismus arabicus (Arabian schismus)Spread is promoted by soil disturbances Yes Guertin (2003)
Sclerophthora rayssiae var. zeae (brown stripe downy mildew of maize) Yes Singh and Renfro (1971)
Sclerospora graminicola (downy mildew of pearl millet)Oospores with crop debris Yes
Scutellonema brachyurus Yes
Scutellonema bradys (yam nematode) Yes
Scutellonema clathricaudatum Yes
Senecio glastifolius (holly-leaved senecio) Yes
Senecio jacobaea (common ragwort)Attached to vehicles Yes
Senecio vulgarisAttached to vehicles Yes
Senna aculeata (senna)Seeds as contaminants Yes Yes Queensland Government (2020)
Senna bacillaris (whitebark senna) Yes Yes
Senna multijuga (November shower)Soil in areas where species is cultivated may be contaminated with seeds and dispersed Yes Yes
Senna occidentalis (coffee senna) Yes Yes
Senna surattensis (golden senna) Yes Yes Little and Skolmen (1989); PIER (2014); Randall (2012); Sosef and Maesen (1997); Wagner et al. (2014)
Sesbania punicea (red sesbania) Yes
Sida repens (Javanese fanpetals) Yes Yes
Solanum elaeagnifolium (silverleaf nightshade)Soil, water, animal faeces Yes Yes
Solanum erianthum (potato tree)Species can spread by adventitious shoots Yes Roe (1979)
Solanum mammosum (nipplefruit nightshade) Yes Yes PBI Solanum Project (2014)
Solanum seaforthianum (Brazilian nightshade)Seeds as a soil-contaminant Yes Yes Gallagher et al. (2010)
Solanum sisymbriifolium (sticky nightshade)Seeds Yes Yes ISSG (2020)
Solanum tuberosum (potato)Soil that contains fragments of tuber can be transported. Tubers are capable of regenerating Yes Yes
Solanum viarum (tropical soda apple)Seeds Yes Yes Medal et al. (2012)
Solenopsis geminata (tropical fire ant) Yes
Solenopsis invicta (red imported fire ant)Whole nest Yes Taber (2000)
Solenopsis richteri (black imported fire ant) Yes
Solidago gigantea (giant goldenrod)Rhizome fragments in soil Yes Yes Weber (2011)
Solidago nemoralis (grey goldenrod)Hypothetical Yes
Sonchus oleraceus (common sowthistle)Seeds as contaminant Yes Yes Holm et al. (1977)
Sorghum halepense (Johnson grass) Yes Yes
Spartium junceum (Spanish broom)Seeds as contaminant in soil Yes Yes Nilsen et al. (1993); Zouhar (2005)
Spiraea chamaedryfolia (germander meadowsweet)Seeds Yes Yes
Spirodela polyrrhiza (giant duckweed)Turions and fronds can be transported in mud attached to aquatic animals Yes Les (2020)
Spongospora subterranea f.sp. subterranea (powdery scab)Soil. Yes
Stachytarpheta cayennensis (blue snakeweed) Yes Smith (2002)
Stictocardia tiliifolia (spottedheart)Possible as it grows on sandy soils near coasts Yes PIER (2019); PROTA (2019)
Streptomyces ipomoeae (Streptomycete soil rot (pox))Soil Yes
Striga asiatica (witch weed)Soil Yes Yes
Symphyotrichum novi-belgii (New York aster) Yes
Syngonium podophyllum (arrowhead vine)Vegetative fragments spread in waste garden soil Yes Yes ISSG (2012)
Tagetes erecta (Mexican marigold)Seeds as contaminant Yes Yes PROTA (2018)
Tanacetum vulgare (tansy)Tansy is often found along rivers. Yes
Taraxacum officinale complex (dandelion)Water - especially irrigation ditches. Yes
Thaumetopoea processionea (oak processionary moth) Yes Forestry Commission (2014)
Theba pisana (white garden snail) Yes Godan (1983)
Thecaphora solani (potato smut)spores or spore masses Yes Abbott (1932); Torres (2001)
Themeda quadrivalvis (grader grass)Contaminant Yes Yes Keir and Vogler (2006)
Thunbergia alata (black eyed Susan) Yes Yes Queensland Department of Primary Industries and Fisheries (2011)
Thunbergia fragrans (whitelady)Seeds, stem fragments, roots, dumped garden waste Yes Yes Starr et al. (2003)
Thunbergia grandiflora (Bengal trumpet)Seeds, cuttings, stem segments, roots Yes Yes Queensland Department of Primary Industries and Fisheries (2007)
Thymophylla tenuiloba (Dahlberg daisy)No information available, but possible escape from cultivation Yes
Tipula paludosa (European crane fly)Possible risk of moving soil. Yes
Tomato brown rugose fruit virus (Tomato brown rugose fruit virus)Contaminated soil from old crop can be source of the virus in the new plantation Yes
Toxicodendron succedaneum (wax tree)Seeds in garden soil Yes Yes NZPCN (2016)
Toxotrypana curvicauda (papaya fruit fly)Risk of puparia in soil. Yes
Tragus racemosus (stalker bur grass)Possible. No information available but as it is an ephemeral species, the seeds that germinate in the summer are at least from the previous season Yes
Tribulus terrestris (puncture vine) Yes
Trophotylenchulus piperis Yes
Tylenchorhynchus annulatus (stunt nematode) Yes
Tylenchorhynchus claytoni (stunt nematode) Yes
Tylenchulus semipenetrans (citrus root nematode) Yes
Typha latifolia (broadleaf cattail)Seeds that become attached via mud Yes DiTomaso and Healy (2003)
Ulex europaeus (gorse) Yes Yes Tulang (1992)
Urena lobata (caesar weed)Spiny fruits and barbed seed Yes Yes Langeland et al. (2008)
Urena sinuata (bur mallow)Spiny fruits and barbed seed Yes Yes Liogier (1988)
Urochloa distachya (signal grass)Seed bank Yes Yes
Urochloa mutica (para grass)Seeds, stem fragments Yes Yes Cook et al. (2005)
Urocystis agropyri (flag smut of wheat) Yes
Verbena officinalis (vervain)Possible, as it is an escape from cultivation and self-seeds Yes Yes Méndez Santos (2002); PFAF (2020)
Vulpia myuros (annual fescue)Seeds Yes Wallace (1997)
Wasmannia auropunctata (little fire ant) Yes Yes
Xanthomonas axonopodis pv. begoniae (bacterial wilt of begonias) Yes
Xanthomonas campestris pv. campestris (black rot)Long survival in soil. Yes
Xanthomonas campestris pv. musacearum (banana xanthomonas wilt (BXW)) Yes
Xanthomonas euvesicatoria pv. alfalfae (bacterial leaf spot of lucerne)Wind-blown soil. Yes
Xanthomonas euvesicatoria pv. euvesicatoria (bacterial spot of tomato and pepper) Yes
Xanthomonas euvesicatoria pv. perforans (bacterial spot of tomato) Yes
Xanthomonas hortorum pv. gardneri (bacterial spot of tomato and pepper) Yes
Xanthomonas translucens pv. cerealis (bacterial leaf streak of grasses) Yes
Xanthomonas translucens pv. translucens (bacterial leaf streak of barley) Yes
Xanthomonas vesicatoria (bacterial spot of tomato and pepper) Yes
Xiphinema americanum (dagger nematode) Yes
Xiphinema diversicaudatum (dagger nematode) Yes
Xiphinema ifacolum (dagger nematode) Yes
Xiphinema index (fan-leaf virus nematode)Grape vines. Yes
Xiphinema rivesi (dagger nematode) Yes
Youngia japonica (oriental false hawksbeard)Seeds Yes Yes USDA-NRCS (2018)
Zeuxine strateumatica (soldier’s orchid)Accidentally introduced with contaminated soil Yes Ames (1938)
Zingiber montanum (cassumunar ginger) Yes Yes
Zingiber zerumbet (shampoo ginger) Yes Yes
Zygotylenchus guevarai Yes


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Management options are concerned with the two sets of risks: long-distance introduction and local spread. Concerning international introductions, reductions of risk revolve around quarantine issues, i.e. acknowledging the risks associated with this pathway and taking adequate preventative measures to reduce them. As inert substrates, they could undergo treatment, as has been assessed in Russia for example. Moskalenko (1993) used, gamma irradiation to kill weed seeds in imported fodders, finding that levels of irradiation required varied considerably according to species, ranging from 30 krad for Ambrosia artemisiifolia to 60 krad for Sesbania sp. and 70 krad for Ipomoea sp. This could equally be applied to soil, sand and gravel, etc.

To reduce the risk of spread, similar methods could be used but may be considered less cost-effective in such cases, Rather, research could identify those sub-pathways of highest risk and then implement management plans accordingly. For example, in Yellowstone National Park, USA, an integrated weed management approach, emphasizing prevention, education, early detection and eradication, control and monitoring includes the requirement for using only gravel from approved sources for construction projects (Olliff et al., 2001). Similar systems could easily be applied elsewhere.


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7/14/2009 Original text by:

Nick Pasiecznik, Consultant, France