Fallopia sachalinensis (giant knotweed)
- Summary of Invasiveness
- Taxonomic Tree
- Notes on Taxonomy and Nomenclature
- Plant Type
- Distribution Table
- History of Introduction and Spread
- Risk of Introduction
- Habitat List
- Hosts/Species Affected
- Biology and Ecology
- Air Temperature
- Rainfall Regime
- Soil Tolerances
- Natural enemies
- Notes on Natural Enemies
- Means of Movement and Dispersal
- Pathway Causes
- Pathway Vectors
- Impact Summary
- Economic Impact
- Environmental Impact
- Social Impact
- Risk and Impact Factors
- Detection and Inspection
- Similarities to Other Species/Conditions
- Prevention and Control
- Gaps in Knowledge/Research Needs
- Links to Websites
- Distribution Maps
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PicturesTop of page
IdentityTop of page
Preferred Scientific Name
- Fallopia sachalinensis (F. Schmidt) Ronse Decr.
Preferred Common Name
- giant knotweed
Other Scientific Names
- Pleuropterus sachalinensis (F.W. Schmidt ex Maxim.) H. Gross
- Polygonum sachalinense F. Schmidt
- Reynoutria sachalinensis (F. Schmidt) Nakai
- Reynoutria vivax J. Schmitz and Strank
- Tiniaria sachalinensis (F.W. Schmidt ex Maxim.) Janch.
Local Common Names
- Poland: rdest sachalinski; rdestowiec sachalinski
Summary of InvasivenessTop of page
F. sachalinensis is a highly invasive rhizomatous perennial plant capable of reaching 4 m in height, outcompeting and displacing native species in particular in riparian zones which it prefers. It has spread to most areas in its exotic range without the aid of seed dispersal though it does provide pollen for the fertilization of F. japonica plants to produce the highly invasive Fallopia x bohemica. Though not considered as problematic as Japanese knotweed (F. japonica), eradication is a real challenge and often unachievable, especially with restrictions applied to chemical use on or near water thus methods of control are limited.
Taxonomic TreeTop of page
- Domain: Eukaryota
- Kingdom: Plantae
- Phylum: Spermatophyta
- Subphylum: Angiospermae
- Class: Dicotyledonae
- Order: Polygonales
- Family: Polygonaceae
- Genus: Fallopia
- Species: Fallopia sachalinensis
Notes on Taxonomy and NomenclatureTop of page
Fallopia sachalinensis has been placed in a number of different genera including Polygonum, Reynoutria, Tiniaria and Pleuropterus, before being accepted as a member of Fallopia, However, it must be noted when searching for information that it is still found in the literature as Reynoutria sachalinensis and transfer back to Reynoutria was proposed by Galasso et al. (2009) based on rbcL plastidial sequence analysis. It is commonly known as giant knotweed, not to be confused with the closely related Japanese knotweed, F. japonica, although all species in the genus Fallopia are collectively known as ‘knotweeds’. F. sachalinensis also hybridizes with F. japonica, forming self-sustaining and even more highly invasive populations of F. xbohemica.
DescriptionTop of page
The following description is taken from the electronic Flora of North America (http://www.efloras.org/flora). Herbs, perennial, rhizomatous, 2-4(-5) m. Stems usually clustered, erect, sparingly branched, herbaceous, stiff, glabrous, glaucous. Leaves: ocrea persistent or deciduous, brownish, cylindric, 6-12 mm, margins oblique, face without reflexed and slender bristles at base, otherwise glabrous or puberulent; petiole 1-4 cm, glabrous; blade ovate-oblong, 15-30(-40) × 7-25 cm, base cordate, margins entire, glabrous or scabrous to ciliate, apex obtuse to acute, abaxial face minutely dotted, glaucous, with hairs along veins distinctly multicellular, 0.2-0.6 mm, tips acute to acuminate, adaxial face glabrous. Inflorescences axillary, mostly distal, erect or spreading, panicle like, 3-8 cm, axes puberulent to pubescent; peduncle 0.1-4 cm or absent, puberulent to reddish-pubescent. Pedicels ascending or spreading, articulated proximal to middle, 2-4 mm, glabrous. Flowers bisexual or pistillate, 4-7 per ocreate fascicle; perianth accrescent in fruit, greenish, 4.5-6.5 mm including stipe-like base, glabrous; tepals obovate to elliptic, apex obtuse to acute, outer 3 winged; stamens 6-8; filaments flattened proximally, glabrous; styles connate basally; stigmas fimbriate. Achenes included, brown, 2.8-4.5 × 1.1-1.8 mm, shiny, smooth; fruiting perianth glabrous, wings flat to undulate, 1.8-2.2 mm wide at maturity, decurrent on stipelike base to articulation, margins entire.
Plant TypeTop of page Broadleaved
DistributionTop of page
F. sachalinensis is a native of Japan (northern Honshu and Hokkaido only), Sakhalin Island (Russia) and possibly the isolated Ullung-do Island between Korea and Japan (Bailey and Conolly, 2000). Sukopp and Starfinger (1995) reports it in the southern Kuril Islands of Kunashir and Shikotan. In Japan it is found from sea-level to 1050 m (Miyawaki, 1989)
Distribution TableTop of page
The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.Last updated: 23 Apr 2020
|Continent/Country/Region||Distribution||Last Reported||Origin||First Reported||Invasive||Reference||Notes|
|South Africa||Present||Introduced||Russell Gibbs et al. (1987)|
|India||Present||CABI (Undated a)||Present based on regional distribution.|
|-West Bengal||Present, Localized||Introduced||Bailey and Conolly (2000)||To stabalise riverbanks|
|Japan||Present||CABI (Undated a)||Present based on regional distribution.|
|-Hokkaido||Present, Widespread||Native||Kanai (2000)|
|-Honshu||Present, Localized||Native||Kanai (2000)|
|Austria||Present, Localized||Introduced||Sukopp and Starfinger (1995); EPPO (2020)||Ref refers to most central and eastern Europe|
|Belgium||Present, Widespread||Introduced||Invasive||Tiébré et al. (2007); EPPO (2020)|
|Bulgaria||Present, Localized||Introduced||Sukopp and Starfinger (1995); EPPO (2020)||Ref refers to most central and eastern Europe|
|Croatia||Present, Localized||Introduced||Sukopp and Starfinger (1995); EPPO (2020)||Ref refers to most central and eastern Europe|
|Czechia||Present, Widespread||Introduced||1921||Invasive||Mandák et al. (2004); EPPO (2020)|
|Denmark||Present, Widespread||Introduced||1950||Invasive||Royal Botanic Garden Edinburgh (2008); EPPO (2020)|
|Estonia||Present, Widespread||Introduced||Invasive||Royal Botanic Garden Edinburgh (2008); EPPO (2020)|
|Finland||Present||Introduced||Invasive||Royal Botanic Garden Edinburgh (2008); EPPO (2020)|
|France||Present, Widespread||Introduced||Invasive||Marigo and Pautou (1998); EPPO (2020)|
|Germany||Present, Widespread||Introduced||1917||Invasive||Schnitzler and Muller (1998); EPPO (2020)|
|Hungary||Present, Localized||Introduced||Sukopp and Starfinger (1995)||Ref refers to most central and eastern Europe|
|Ireland||Present, Widespread||Introduced||Invasive||Royal Botanic Garden Edinburgh (2008); EPPO (2020)|
|Italy||Present, Localized||Introduced||Invasive||DAISIE (2008)|
|Lithuania||Present, Localized||Introduced||Sukopp and Starfinger (1995)||Ref refers to most central and eastern Europe|
|Luxembourg||Present, Localized||Introduced||Invasive||DAISIE (2008)|
|Netherlands||Present, Localized||Introduced||Invasive||DAISIE (2008); EPPO (2020)|
|Norway||Present||Invasive||Fremstad and Elven (1997); EPPO (2020)|
|Poland||Present, Widespread||Introduced||Invasive||Royal Botanic Garden Edinburgh (2008); EPPO (2020)|
|Romania||Present, Localized||Introduced||Sukopp and Starfinger (1995)||Ref refers to most central and eastern Europe|
|Russia||Present, Localized||EPPO (2020)|
|-Central Russia||Present||Introduced||Royal Botanic Garden Edinburgh (2008); EPPO (2020)|
|-Northern Russia||Present, Only in captivity/cultivation||Introduced||Regel (1864); Sukopp and Starfinger (1995)|
|-Russian Far East||Present||Morozov (1978); USDA-ARS (2008); EPPO (2020)|
|-Southern Russia||Present||Introduced||Royal Botanic Garden Edinburgh (2008)|
|Serbia||Present, Localized||Introduced||Sukopp and Starfinger (1995)|
|Slovakia||Present, Localized||Introduced||Sukopp and Starfinger (1995)||Ref refers to most central and eastern Europe|
|Slovenia||Present, Localized||Introduced||Sukopp and Starfinger (1995); EPPO (2020)||Ref refers to most central and eastern Europe|
|Spain||Present, Only in captivity/cultivation||Introduced||Invasive||DAISIE (2008); EPPO (2020)|
|Sweden||Present, Localized||Introduced||Invasive||Royal Botanic Garden Edinburgh (2008); EPPO (2020)|
|Switzerland||Present, Localized||Introduced||Invasive||Jeanmonod (2005); EPPO (2020)|
|United Kingdom||Present, Localized||Introduced||Invasive||Pashley et al. (2007); EPPO (2020)||First reported: 1800s|
|Canada||Present||CABI (Undated a)||Present based on regional distribution.|
|-British Columbia||Present||Introduced||USA, USDA-NRCS (2008)|
|-New Brunswick||Present||Introduced||USA, USDA-NRCS (2008)|
|-Newfoundland and Labrador||Present||Introduced||USA, USDA-NRCS (2008)|
|-Nova Scotia||Present||Introduced||USA, USDA-NRCS (2008)|
|-Nunavut||Present||CABI (Undated)||Original citation: eFloras (2008)|
|-Ontario||Present||Introduced||USA, USDA-NRCS (2008)|
|-Prince Edward Island||Present||Introduced||USA, USDA-NRCS (2008)|
|-Quebec||Present||Introduced||USA, USDA-NRCS (2008)|
|United States||Present||CABI (Undated a)||Present based on regional distribution.|
|-Alaska||Present||Introduced||USA, USDA-NRCS (2008)|
|-California||Present, Localized||Introduced||Invasive||USA, USDA-NRCS (2008)|
|-Connecticut||Present, Localized||Introduced||USA, USDA-NRCS (2008)|
|-Delaware||Present||Introduced||USA, USDA-NRCS (2008)|
|-Idaho||Present, Localized||Introduced||USA, USDA-NRCS (2008)|
|-Illinois||Present, Localized||Introduced||Invasive||USA, USDA-NRCS (2008)||Invasiveness confirmed by Swearingen (2006)|
|-Louisiana||Present, Localized||Introduced||Invasive||USA, USDA-NRCS (2008)|
|-Maine||Present, Localized||Introduced||Invasive||USA, USDA-NRCS (2008)||Invasiveness confirmed by Swearingen (2006)|
|-Maryland||Present, Localized||Introduced||Invasive||USA, USDA-NRCS (2008)||Invasiveness confirmed by Swearingen (2006)|
|-Massachusetts||Present, Localized||Introduced||Invasive||USA, USDA-NRCS (2008)|
|-Michigan||Present, Localized||Introduced||Invasive||USA, USDA-NRCS (2008)||Invasiveness confirmed by Swearingen (2006)|
|-Minnesota||Present, Localized||Introduced||Invasive||USA, USDA-NRCS (2008)||Invasiveness confirmed by Swearingen (2006)|
|-Montana||Present, Localized||Introduced||Invasive||USA, USDA-NRCS (2008)|
|-New Jersey||Present, Localized||Introduced||Invasive||USA, USDA-NRCS (2008)|
|-New York||Present, Localized||Introduced||Invasive||USA, USDA-NRCS (2008)|
|-North Carolina||Present, Localized||Introduced||Invasive||USA, USDA-NRCS (2008)||Invasiveness confirmed by Swearingen (2006)|
|-Ohio||Present, Localized||Introduced||Invasive||USA, USDA-NRCS (2008)|
|-Oregon||Present, Widespread||Introduced||Invasive||USA, USDA-NRCS (2008)||Invasiveness confirmed by Swearingen (2006)|
|-Pennsylvania||Present, Localized||Introduced||Invasive||USA, USDA-NRCS (2008)|
|-Rhode Island||Present, Localized||Introduced||Invasive||USA, USDA-NRCS (2008)||Invasiveness confirmed by Swearingen (2006)|
|-Tennessee||Present, Localized||Introduced||Invasive||USA, USDA-NRCS (2008)|
|-Vermont||Present||Introduced||USA, USDA-NRCS (2008)|
|-Virginia||Present, Localized||Introduced||Invasive||USA, USDA-NRCS (2008)|
|-Washington||Present, Localized||Introduced||Invasive||USA, USDA-NRCS (2008)||Invasiveness confirmed by Swearingen (2006)|
|-West Virginia||Present||Introduced||USA, USDA-NRCS (2008)|
|-Wisconsin||Present, Localized||Introduced||Invasive||USA, USDA-NRCS (2008)||Invasiveness confirmed by Swearingen (2006)|
|Australia||Present||CABI (Undated a)||Present based on regional distribution.|
|-New South Wales||Present, Localized||Introduced||Invasive||Royal Botanic Garden Edinburgh (2008)|
|-Victoria||Present, Localized||Introduced||Royal Botanic Garden Edinburgh (2008)|
|New Zealand||Present||Introduced||1935||Invasive||CABI (Undated b)|
History of Introduction and SpreadTop of page
The plant was first discovered by Dr H Weyrich in Sakhalin during a Russian naval expedition from 1852-55, bringing it to St Petersburg in 1864 and it was reported as growing in the city’s botanical gardens in the same year (Regel, 1864). It was introduced to the UK in the late 1860s, first appearing for sale in the 1869-70 catalogue (no. 48) of the horticulturalist William Bull of Chelsea. In The Garden (vol xiii, 1878), it was referred to as even more vigorous than Polygonum cuspidatum (= F. japonica) and well adapted to the wild garden, and if well placed on the edge of a shrubbery it will well repay the planter. It was recommended as a forage plant for cattle in Europe (Andre, 1893) and was even established in Bengal as a riverbank stabilizer where it still persists (Bailey and Conolly, 2000). It was introduced to New Zealand in 1935 (Owen, 1996) and also to Victoria and New South Wales, Australia. It is also recorded in South Africa from as early as 1987 (Russell Gibbs et al., 1987). Dates of first introduction to North America are not reported though it is now found in most states of the USA and provinces of Canada.
IntroductionsTop of page
|Introduced to||Introduced from||Year||Reason||Introduced by||Established in wild through||References||Notes|
|Natural reproduction||Continuous restocking|
|Europe||Japan||1863||Food (pathway cause)
Ornamental purposes (pathway cause)
|Yes||Sukopp and Starfinger (1995)|
|Russian Federation||Japan||1859||Botanical gardens and zoos (pathway cause)||Bailey and Conolly (2000)|
|UK||Japan||1859||Botanical gardens and zoos (pathway cause)||Yes||Bailey and Conolly (2000)|
Risk of IntroductionTop of page
F. sachalinensis is fairly well known by, and unpopular with, the gardening public so the risk of new introductions in areas where ‘knotweeds’ have become problematic are unlikely. It is possible that an unwitting public may purchase the plant from unscrupulous sellers but the chance of this is fairly small. It could arrive in new areas as a result of the import of contaminated soil. It is a regulated species in four states of the USA, and the closely related Japanese knotweed is a declared weed much more widely in Europe and North America.
HabitatTop of page
In its adventive range it is found either in sites more or less influenced by human activities such as gardens, parks and ruderal sites in towns and villages, often close to planted individuals, or along watercourses in near-natural conditions.
Habitat ListTop of page
|Terrestrial – Managed||Disturbed areas||Principal habitat||Harmful (pest or invasive)|
|Rail / roadsides||Principal habitat||Harmful (pest or invasive)|
|Urban / peri-urban areas||Principal habitat||Harmful (pest or invasive)|
|Terrestrial ‑ Natural / Semi-natural||Natural forests||Secondary/tolerated habitat||Productive/non-natural|
|Natural grasslands||Secondary/tolerated habitat||Harmful (pest or invasive)|
|Riverbanks||Principal habitat||Harmful (pest or invasive)|
|Wetlands||Secondary/tolerated habitat||Harmful (pest or invasive)|
|Coastal dunes||Secondary/tolerated habitat||Harmful (pest or invasive)|
Hosts/Species AffectedTop of page
Any riparian species would be vulnerable to displacement by giant knotweed and those natives that are threatened and not widely distributed would be more vulnerable to localized extinction. The most common species associated with the plant relevés in Germany were Urtica dioca, Artemisia vulgaris, Poa palustris, P. trivialis and Aegopodium podagraria (Dettmar, 1991).
Biology and EcologyTop of page Genetics
Physiology and Phenology
ClimateTop of page
|Cf - Warm temperate climate, wet all year||Tolerated||Warm average temp. > 10°C, Cold average temp. > 0°C, wet all year|
|Cs - Warm temperate climate with dry summer||Preferred||Warm average temp. > 10°C, Cold average temp. > 0°C, dry summers|
|Cw - Warm temperate climate with dry winter||Tolerated||Warm temperate climate with dry winter (Warm average temp. > 10°C, Cold average temp. > 0°C, dry winters)|
|Df - Continental climate, wet all year||Tolerated||Continental climate, wet all year (Warm average temp. > 10°C, coldest month < 0°C, wet all year)|
|Ds - Continental climate with dry summer||Preferred||Continental climate with dry summer (Warm average temp. > 10°C, coldest month < 0°C, dry summers)|
|Dw - Continental climate with dry winter||Tolerated||Continental climate with dry winter (Warm average temp. > 10°C, coldest month < 0°C, dry winters)|
Air TemperatureTop of page
|Parameter||Lower limit||Upper limit|
|Absolute minimum temperature (ºC)||-40||0|
|Mean annual temperature (ºC)||4||8|
|Mean maximum temperature of hottest month (ºC)||16||26|
|Mean minimum temperature of coldest month (ºC)||-9||-3|
RainfallTop of page
|Parameter||Lower limit||Upper limit||Description|
|Dry season duration||0||0||number of consecutive months with <40 mm rainfall|
|Mean annual rainfall||500||1200||mm; lower/upper limits|
Rainfall RegimeTop of page Bimodal
Soil TolerancesTop of page
- seasonally waterlogged
Special soil tolerances
Natural enemiesTop of page
Notes on Natural EnemiesTop of page
The congeneric F. japonica has been subject to research into biological control since 1999, and in that time dozens of natural enemies have been recorded on F. sachalinensis in its native range, in contrast with very few that have been found in its introduced range.
Means of Movement and DispersalTop of page Natural Dispersal (Non-biotic)
Vector Transmission (Biotic)
Pathway CausesTop of page
|Botanical gardens and zoos||Most introductions began in botanical gardens||Yes||Bailey, 1989|
|Escape from confinement or garden escape||very common indeed||Yes||Bailey and Conolly, 2000|
|Flooding and other natural disasters||Yes||Sukopp and Starfinger, 1995|
|Garden waste disposal||flytipping common issue in UK||Yes|
|Habitat restoration and improvement||Even exported to India||Yes||Bailey and Conolly, 2000|
|Horticulture||Originally but not anymore||Yes|
|Intentional release||It is planted as a crop in Germany for the production of Milsana||Yes|
|Interconnected waterways||During flood events||Yes|
Pathway VectorsTop of page
Impact SummaryTop of page
Economic ImpactTop of page
F. sachalinensis, like Japanese knotweed is difficult and expensive to control, and the economic impacts are felt mainly through the costs of control efforts. It is also considered alongside Japanese knotweed when assessing potential building land in the UK and its presence can add up to 10% on the total project cost. Although not found to cause disease within cattle, cattle fed on the plant exhibited transient anorexia and hypothermia (Suzuki et al., 1985).
Environmental ImpactTop of page
F. sachalinensis is suspected to alter critical riparian processes including forest and understory regeneration, streambank stability, soil nutrient cycling and allochthonous litter inputs.Impact on Habitats
Impact on Biodiversity
Social ImpactTop of page
Like Japanese knotweed, F. sachalinensis is often associated with neglected and disturbed urban environments and as such can have a social impact and be a symbol of decay and a lack of investment.
Risk and Impact FactorsTop of page Invasiveness
- Proved invasive outside its native range
- Abundant in its native range
- Highly adaptable to different environments
- Is a habitat generalist
- Tolerates, or benefits from, cultivation, browsing pressure, mutilation, fire etc
- Pioneering in disturbed areas
- Long lived
- Fast growing
- Has propagules that can remain viable for more than one year
- Reproduces asexually
- Damaged ecosystem services
- Ecosystem change/ habitat alteration
- Increases vulnerability to invasions
- Infrastructure damage
- Loss of medicinal resources
- Modification of fire regime
- Modification of hydrology
- Modification of natural benthic communities
- Monoculture formation
- Negatively impacts tourism
- Reduced amenity values
- Reduced native biodiversity
- Threat to/ loss of native species
- Interaction with other invasive species
- Rapid growth
- Difficult to identify/detect as a commodity contaminant
- Difficult/costly to control
UsesTop of page
Detection and InspectionTop of page
Identification of newly propagated plants is possible, but rhizomes are hard to distinguish from other invasive knotweeds.
Similarities to Other Species/ConditionsTop of page
Giant knotweed is very closely-related to Japanese knotweed, F. japonica although it can be distinguished fairly easily as it is generally a much larger plant, 4-5 m tall with much larger leaves 20-40 cm long, with trichomes present on the underside, and also distinguished by the base of the leaf which in F. sachalinensis is rounded acuminate forming a heart shape. More difficult to distinguish is their hybrid F. xbohemica which has an intermediate leaf size and shape between the two parents. A useful key to the identification of invasive knotweeds has been developed for British Columbia, Canada and includes drawings and photographs (Wilson, 2007).
Prevention and ControlTop of page
Due to the variable regulations around (de)registration of pesticides, your national list of registered pesticides or relevant authority should be consulted to determine which products are legally allowed for use in your country when considering chemical control. Pesticides should always be used in a lawful manner, consistent with the product's label.
Early warning systems
If a recently established patch is identified, then treatments with systemic herbicides after the plant has reached full height are most likely to kill the plant. However, digging out as much rhizome as possible is advantageous prior to a spraying regime.
Giant knotweed is presumed to be as difficult to eradicate as Japanese knotweed since it also benefits from a very large rhizome system with an ability to regenerate from very small fragments of rhizome. In the UK, the Environment Agency has produced a Code of Practice for knotweed management which provides information on control measures and management on development sites. Eradication can be achieved by the removal of the whole plant and the contaminated soil to landfill sites but this is far from sustainable. Various companies have been set up in the UK that guarantee total knotweed eradication, though the value of these guarantees is yet to be tested. Some companies avoid landfill by using mechanical sieves to remove the majority of rhizome from the extracted soil and then follow-up spot spraying for any small plants that do re-establish.
The use of physical barriers is common in building sites in the UK, where thick rubberized sheeting is used to create a sealed parcel of contaminated soil underground.
Japanese knotweed infested soil is dealt with as a contaminated waste issue in the UK, and as such its transport and burial are regulated by the Environment Agency.
A biological control programme has been underway since 2003 against the closely related Japanese knotweed, which has involved research on behalf of the UK, USA and Canada. In this time, surveys have been undertaken in Northern Honshu and Hokkaido where giant knotweed is the dominant or only knotweed in the area. Numerous natural enemies of giant knotweed have been identified including a northern strain of the sap-sucking psyllid Aphalara itadori, the chrysomelid beetle Gallerucida bifasciata and the pyralid moth Ostrinia ovalipennis amongst many other arthropods and fungi. Giant knotweed has not been the priority target so far but it is included in the host range testing procedures undertaken by the partner institutions so potential biological control agents may emerge in this on-going collaborative research project
It is rare to find specific information about the control of giant knotweed as separated from the more common Japanese knotweed for which there has been much written. In general the key to successful control with chemicals is to use a systemic chemical once the plant has reached its full height but before the first winter frost. In this way, the largest leaf to rhizome ration is presented and proportionally more chemical is absorbed through the leaves and moved along with the carbohydrates to kill the root. Herbicides containing glyphosate can be effective and have an advantage over the more persistent herbicides containing imazypyr, picloram and dicamba in that they have a lower soil activity. Care must be taken when using chemicals in general and especially on or near water where restrictions exist.
With limited sexual reproduction in the introduced range there is no evidence of variable resistance to chemical treatments.
Combined treatments were also found to be more successful on F. sachalinensis than on two other taxa (Bímová et al., 2001). F. japonica was best controlled by the combined treatment consisting of digging and subsequent herbicide application. F. sachalinensis was well controlled by both the combined treatments and by purely mechanical disturbance of underground biomass. Combination treatments can provide more cost-effective control than purely chemical or mechanical measures (Child et al., 1998) and normally involves disturbance followed by systemic chemical treatment.
Control by utilization
Whereas giant knotweed can be eaten, used as a source of medicinal or anti-microbial products or as a biofuel, these resources are recovered from crop situations rather than invasive infestations.
Monitoring and Surveillance
GIS mapping and public questionnaires have been used to establish the extent of Japanese knotweed in the UK and USA and are often included in management plans.
Following giant knotweed control there may be a need to re-establish native plant species if the control measures have left bare and disturbed ground.
Gaps in Knowledge/Research NeedsTop of page
More information on the genetic diversity and distribution of giant knotweed in North America would be useful. In addition, a biocontrol programme against this species appears justified.
ReferencesTop of page
Bímová K; Mandák B; Py?ek P, 2001. Experimental control of Reynoutria congeners: A comparative study of a hybrid and its parents. In: Plant Ecology, Species Ecology and Ecosystem Management [ed. by Brundu G, Brock J, Camarda I, Child L, Wade L] Leiden, Netherlands: Backhuys Publishers, 283-290.
Child L; Wade M, 2000. The Japanese knotweed manual: the management and control of an invasive alien weed. The Japanese knotweed manual: the management and control of an invasive alien weed, xi + 123 pp.
Child LE; Wade PM; Wagner M, 1998. Cost effective control of Fallopia japonica using combination treatments. In: Plant Invasions: Ecological Mechanisms and Human Responses [ed. by Starfinger U, Edwards K, Kowarik I, Williamson , M] Leiden, Netherlands: Backhuys Publishers, 143-154.
EPPO, 2014. PQR database. Paris, France: European and Mediterranean Plant Protection Organization. http://www.eppo.int/DATABASES/pqr/pqr.htm
Galasso G; Banfi E; Mattia FDe; Grassi F; Sgorbati S; Labra M, 2009. Molecular phylogeny of Polygonum L. (Polygonoideae, Polygonaceae), focusing on European taxa: preliminary results and systematic considerations based on rbcL plastidial sequence data. Atti della Società italiana di scienze naturali e del Museo civico di storia naturale di Milano, 150(1):113-148.
Gammon MA; Grimsby JL; Tsirelson D; Kesseli R, 2007. Molecular and morphological evidence reveals introgression in swarms of the invasive taxa Fallopia japonica, F. sachalinensis and F. bohemica (Polygonaceae) in the United States. American Journal of Botany, 94(6):948-956. http://www.amjbot.org/
Gerber E; Krebs C; Murrell C; Moretti M; Rocklin R; Schaffner U, 2008. Exotic invasive knotweeds (Fallopia spp.) negatively affect native plant and invertebrate assemblages in European riparian habitats. Biological Conservation, 141(3):646-654. http://www.sciencedirect.com/science/journal/00063207
Gibbs Russell GE; Welman WG; Reitief E; Immelman KL; Germishuizen G; Pienaar BJ; Wyk Mvan; Nicholas A, 1987. List of species of southern African plants. Memoirs of the Botanical Survey of South Africa, 2(1 & 2):1-152 & 1-270.
Grimsby JL; Tsirelson D; Gammon MA; Kesseli R, 2007. Genetic diversity and clonal vs. sexual reproduction in Fallopia spp. (Polygonaceae). American Journal of Botany, 94(6):957-964. http://www.amjbot.org/
Hollingsworth ML; Hollingsworth PM; Jenkins GI; Bailey JP; Ferris C, 1998. The use of molecular markers to study patterns of genotypic diversity in some invasive alien Fallopia spp. (Polygonaceae). Molecular Ecology, 7(12):1681-1691.
Hrušková H; Hofbauer J, 1999. Regeneration of knotweed (Reynoutria spp.) from stem cuttings. (Regenerace krídlatky (Reynoutria spp.) ze stonkových rízku.) Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis, 47(3):73-76.
Jeanmonod D, 2005. The situation in Switzerland, especially in French-speaking Switzerland. (La situation en Suisse, notamment en Suisse romande.) Revue Horticole Suisse, 78(1/2):32-38. http://www.lullier.ch
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20/05/08 Original text by:
Dick Shaw, CABI Europe - UK, Bakeham Lane, Egham, Surrey TW20 9TY, UK
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