Taxonomy

Persicaria perfoliata | Asiatic tearthumb

Pre 2017

2017 - 2020

Status

Legal status

Regulated invasive species of Union concern under the European Regulation on the prevention and management of the introduction and spread of invasive alien species [1143/2014].

Invasiveness

Invasive species - risk of Medium Impact

Irish status

Absent

Introduction pathways - 1

Transport Contaminant

Introduction pathways subclass - 1

Contaminant nursery material

Invasive score

14

NAPRA Ireland risk assessed

Yes. This species underwent a Non-native species APplication based Risk Analysis in 2014.

Overall risk of this species to Ireland is categorised as: MAJOR with a MEDIUM level of confidence.

Overall conclusion summary: Potential establishment and spread of P. perfoliata in Ireland is likely to have significant economic and environmental impacts. The species is known to grow rapidly, scrambling over shrubs and other vegetation, blocking the foliage of covered plants from available light and reducing their ability to photosynthesize, which stresses and weakens them. As a result of this competition, which includes monopolising resources, shading, smothering, strangling and rapid growth, P. perfoliata has the potential to be a problem to nursery and horticulture crops and semi-natural habitats and areas of conservation interest. 

View the full risk assessment: http://nonnativespecies.ie/wp-content/uploads/2014/03/Persicaria-perfoliata-Mile-a-minute-Weed.pdf

Species Biology

Identification

Annual, thorned prickly vine, which can scramble up shrubs and trees to a height of 6m (Ding, 2009). Leaves are paper-like, alternate, light-green, triangular with backward facing thorns along the central line underneath (Ding, 2009). Stems reddish in colour (GISD, 2015), covered in recurved thorns and have circular bracts (ocrea) at nodes. Clusters of tiny white flowers are borne on racemes and emerge from within the ocreas (Ding, 2009). Fruits are deep blue berries containing achenes and carried in clusters. Roots shallow and fibrous (Ding, 2009).

Ecology

A scrambler that creates dense cover that blocks the light, strangles and outcompetes native species including trees. Fast growing, up to 15cm per day (EPPO, 2007) it is also known as the mile-a-minute weed. Tolerates a wide range of temperatures (Ding, 2009). Prefers full sun but will tolerate partial shade (NPS, 2009). Prefers wet ground but can be found at dry sites (Ding, 2009). May impact orchards and both commercial and regeneration forests (EPPO, 2007). Heavy infestations can be impenetrable and may prevent access to amenities as well as the movement of wildlife (Ding, 2009). Dies back with the first frost (NPS, 2009).

Reproduction

Reproduces by seed. Mainly self-pollinated and doesn't require pollinators (NPS, 2009). 50-100 seeds are produced by each plant (EPPO, 2008) and can remain viable in the seedbank for up to 6 years (NPS, 2009). Seeds germinate early to mid-March and through April (EPPO, 2007). A period of cold exposure of 10°C or less for 8 weeks is necessary for germination to commence (EPPO, 2008). Seeds remain viable in the soil even in very cold temperatures (EPPO, 2007).

Pathway and vector description

Reproduces by seed. Mainly self-pollinated and doesn't require pollinators (NPS, 2009). 50-100 seeds are produced by each plant (EPPO, 2008) and can remain viable in the seedbank for up to 6 years (NPS, 2009). Seeds germinate early to mid-March and through April (EPPO, 2007). A period of cold exposure of 10°C or less for 8 weeks is necessary for germination to commence (EPPO, 2008). Seeds remain viable in the soil even in very cold temperatures (EPPO, 2007).

Mechanism of impact

Competition

Management approach

There is currently an EU wide ban on the sale, growing and keeping of this plant (European Commission, 2017).

Eradication is possible but success will be dependent on early detection.

Prevention

Establishment can be prevented along streams and forests by maintaining margins of thick vegetation (NPS, 2009).

Manual

Hand-pulling is very effective but thick clothing and gloves should be worn when tackling plants larger than seedlings (NPS, 2009). Repeating this several times in a season is likely to be necessary (NPS, 2009).

Mechanical

For younger plants that are out in the open regular mowing will prevent flowering thus allowing control to be achieved (Ding, 2009).

Chemical

Glyphosate and triclopyr are effective (NPS, 2009) and some formulations are approved for use near water. The EPPO (2008) regards the application of pre-emergent herbicides as most effective.

Disposal

The vines can be balled up and left in place or burned.

Monitoring

Infested areas must be regularly monitored for seedlings for several years post control until the seed bank has been exhausted (NPS, 2009).

Broad environment

Terrestrial

Habitat description

Prefers moist ground but will grow on dry land (ding, 2009). Establishes in disturbed areas, wetlands, stream banks, grasslands, road and rail sides, forest and wood margins, scrub-land and ditches.

Species group

Plant

Native region

Temperate Asia, Tropical Asia

Similar species

Persicaria arifolia and P. sagittata. P. Perfoliata can be distinguished by its ocreas, the recurved thorns along the stems and leaf undersides and the triangular leaves.

Distribution

World distribution(GBIF)

Invasive in the USA. Naturalised in Turkey.

Native distribution

Native to India, China, Indonesia, Malaysia, Nepal, Korea, Japan, Bangladesh and the Philippines.

Temporal change

Records submitted to Data Centre in 2021

The following map is interactive. If you would prefer to view it full screen then click here.

How can you help

Report any sightings to the National Biodiversity Data Centre. Do not purchase or plant in your garden. Dispose of any garden plants or weeds responsibly.

Further information

New Zealand has successfully eradicated the plant (EPPO, 2007). There was one record of its presence in Canada in 1954 but nothing since (EPPO, 2007). It is not yet present in the EU but could potentially cause major damage to freshwater ecosystems, commercial forests and forest regeneration (EPPO, 2007).

References

Publications

Ding, J (2009) Invasive Species Compendium. Datasheet report for Persicaria perfoliata (Mile-a-minute weed). Wallingford, UK: CAB International. http://www.cabi.org/isc/datasheetreport?dsid=109155 Site accessed 22 September 2017.

European and Mediterranean Plant Protection Organisation (EPPO) (2008). Mini datasheet on Polygonum perfoliatum https://gd.eppo.int/taxon/POLPF/documents Site accessed 22 September 2017.

European and Mediterranean Plant Protection Organisation (EPPO) (2007). Report of a pest risk analysis- Polygonum perfoliatum L. (POLPF). EPPO. Paris. https://gd.eppo.int/taxon/POLPF/documents Site accessed 22 September 2017.

European Commission. (2017). Invasive Alien Species of Union Concern. European Union, Luxembourg.

Global Invasive Species Database (GISD) 2015. Species profile Persicaria perfoliata. Available from: http://www.iucngisd.org/gisd/species.php?sc=582 Site accessed 22 September 2017.

NPS (2009). Weeds gone wild, alien plant invaders of natural areas. Factsheet Mile-a-minute weed. Washington, USA: National Park Service, US Department of the Interior. https://www.nps.gov/plants/alien/fact/pdf/pepe1.pdf Site accessed 23 September 2017.

CABI Datasheet


Additional comments

Also known as Polygonum perfoliata.

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