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==Invasive species==
==Invasive species==
[[Image:WEEDS054.jpg|thumb|right|180px|Old stems remain in place as new growth appears]]
[[Image:WEEDS054.jpg|thumb|right|180px|Old stems remain in place as new growth appears]]
In the U.S.A. and Europe, Japanese knotweed is widely considered an [[invasive species]] or [[weed]].<ref>[http://www.invasive.org/eastern/biocontrol/12Knotweed.html Biological control of invasive plants in the Eastern United States]</ref> It is listed by the [[World Conservation Union]] as one of the world's 100 worst invasive species.<ref>[http://www.issg.org/database/species/search.asp?st=100ss IUCN Global Invasive Species Database]</ref> It is a frequent colonizer of [[temperate]] [[riparian]] [[ecosystem]]s, roadsides and waste places. It forms thick, dense colonies that completely crowd out any other herbaceous species and is now considered one of the worst invasive exotics in parts of the eastern United States. The success of the species has been partially attributed to its tolerance of a very wide range of soil types, pH and salinity.<ref>[http://www.t-c-m-rd.co.uk/invasive-weeds/japanese-knotweed/ Japanese Knotweed]</ref> Its [[rhizomes]] can survive temperatures of {{convert|-35|°C|°F|sigfig=2}} and can extend {{convert|7|m|ft}} horizontally and {{convert|3|m|ft}} deep, making removal by excavation extremely difficult. The plant is also resilient to cutting, vigorously re-sprouting from the roots. The most effective method of control is by [[herbicide]] application close to the flowering stage in late summer or autumn. In some cases it is possible to eradicate Japanese knotweed in one growing season using only herbicides.<ref>[http://www.ecocontrol.co.uk/eradication-services.asp Single Season Eradication of Japanese Knotweed]</ref> Trials in the [[Queen Charlotte Islands]] (Haida Gwaii) of British Columbia using sea water sprayed on the foliage have demonstrated promising results, which may prove to be a viable option for eradication where concerns over herbicide application are too great.{{Fact|date=July 2008}}
In the U.S.A. and Europe, Japanese knotweed is widely considered an [[invasive species]] or [[weed]].<ref>[http://www.invasive.org/eastern/biocontrol/12Knotweed.html Biological control of invasive plants in the Eastern United States]</ref> It is listed by the [[World Conservation Union]] as one of the world's 100 worst invasive species.<ref>[http://www.issg.org/database/species/search.asp?st=100ss IUCN Global Invasive Species Database]</ref> In Britain it was made illegal to spread Japanese knotweed under the Wildlife and Countryside Act 1981. It is also classed as 'controlled waste' under the Environmental Protection Act 1990. This requires disposal at licensed landfill sites.<ref>[http://www.edible-plants.com/jap_knotweed.html]</ref>
It is a frequent colonizer of [[temperate]] [[riparian]] [[ecosystem]]s, roadsides and waste places. It forms thick, dense colonies that completely crowd out any other herbaceous species and is now considered one of the worst invasive exotics in parts of the eastern United States. The success of the species has been partially attributed to its tolerance of a very wide range of soil types, pH and salinity.<ref>[http://www.t-c-m-rd.co.uk/invasive-weeds/japanese-knotweed/ Japanese Knotweed]</ref> Its [[rhizomes]] can survive temperatures of {{convert|-35|°C|°F|sigfig=2}} and can extend {{convert|7|m|ft}} horizontally and {{convert|3|m|ft}} deep, making removal by excavation extremely difficult. The plant is also resilient to cutting, vigorously re-sprouting from the roots. The most effective method of control is by [[herbicide]] application close to the flowering stage in late summer or autumn. In some cases it is possible to eradicate Japanese knotweed in one growing season using only herbicides.<ref>[http://www.ecocontrol.co.uk/eradication-services.asp Single Season Eradication of Japanese Knotweed]</ref> Trials in the [[Queen Charlotte Islands]] (Haida Gwaii) of British Columbia using sea water sprayed on the foliage have demonstrated promising results, which may prove to be a viable option for eradication where concerns over herbicide application are too great.{{Fact|date=July 2008}}


It can be found in 39 of the 50 [[United States]] ([http://plants.usda.gov:8080/plants//nameSearch?keywordquery=fallopia+japonica PUSDA]) and in six provinces in [[Canada]]. The species is also common in Europe. In the [[United Kingdom|U.K.]] it was made illegal to spread Japanese knotweed by the [[Wildlife and Countryside Act 1981]]. In the U.S.A. it is listed as an invasive weed in Ohio, Vermont, Virginia, New York, Alaska, Pennsylvania, Oregon and Washington state.<ref>[http://www.invasivespeciesinfo.gov/plants/knotweed.shtml USDA weed profile for Japanese knotweed]</ref>
It can be found in 39 of the 50 [[United States]] ([http://plants.usda.gov:8080/plants//nameSearch?keywordquery=fallopia+japonica PUSDA]) and in six provinces in [[Canada]]. The species is also common in Europe. In the [[United Kingdom|U.K.]] it was made illegal to spread Japanese knotweed by the [[Wildlife and Countryside Act 1981]]. In the U.S.A. it is listed as an invasive weed in Ohio, Vermont, Virginia, New York, Alaska, Pennsylvania, Oregon and Washington state.<ref>[http://www.invasivespeciesinfo.gov/plants/knotweed.shtml USDA weed profile for Japanese knotweed]</ref>
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[[Image:Knotweed054.jpg|thumb|right|Erect inflorescence]]
[[Image:Knotweed054.jpg|thumb|right|Erect inflorescence]]
The young stems are edible as a spring [[vegetable]], with a flavor similar to mild [[rhubarb]]. In some locations, semi-cultivating Japanese knotweed for food has been used as a means of controlling knotweed populations that invade sensitive wetland areas and drive out the native vegetation.<ref>[http://www.newtritionink.de Pilot project of Bionic Knotweed Control in Wiesbaden, Germany]</ref>
The young stems are edible as a spring [[vegetable]], with a flavor similar to mild [[rhubarb]]. In some locations, semi-cultivating Japanese knotweed for food has been used as a means of controlling knotweed populations that invade sensitive wetland areas and drive out the native vegetation.<ref>[http://www.newtritionink.de Pilot project of Bionic Knotweed Control in Wiesbaden, Germany]</ref> Some caution should be exercised when consuming this plant because of it contains oxalic acid, which may aggravate conditions such as rheumatism, arthritis, gout, kidney stones or hyperacidity.<ref>[http://www.edible-plants.com/jap_knotweed.html]</ref>


Both Japanese knotweed and giant knotweed are important concentrated sources of [[resveratrol]], replacing grape byproducts.<ref>[http://www.myrevgenetics.com/kb_results.asp?ID=14 Resveratrol Purity]</ref> Many large supplement sources of resveratrol now use Japanese knotweed and use its scientific name in the supplement labels.<ref>[http://www.myrevgenetics.com/kb_results.asp?ID=34 Resveratrol]</ref> The plant is useful because of its year-round growth and robustness in different climates.<ref>[http://www.uoguelph.ca/pdc/Factsheets/PlantID/Japanese_knotweed.htm Pest Diagnostic Unit, University of Guelph]</ref>
Both Japanese knotweed and giant knotweed are important concentrated sources of [[resveratrol]], replacing grape byproducts.<ref>[http://www.myrevgenetics.com/kb_results.asp?ID=14 Resveratrol Purity]</ref> Many large supplement sources of resveratrol now use Japanese knotweed and use its scientific name in the supplement labels.<ref>[http://www.myrevgenetics.com/kb_results.asp?ID=34 Resveratrol]</ref> The plant is useful because of its year-round growth and robustness in different climates.<ref>[http://www.uoguelph.ca/pdc/Factsheets/PlantID/Japanese_knotweed.htm Pest Diagnostic Unit, University of Guelph]</ref>

Revision as of 19:50, 26 July 2009

Japanese Knotweed
Scientific classification
Kingdom:
Plantae
Division:
Magnoliophyta
Class:
Magnoliopsida
Order:
Caryophyllales
Family:
Polygonaceae
Genus:
Fallopia
Species:
F. japonica
Binomial name
Fallopia japonica
Houtt. (Ronse Decr.)

Japanese Knotweed (Fallopia japonica, syn. Polygonum cuspidatum, Reynoutria japonica) is a large, herbaceous perennial plant, native to eastern Asia in Japan, China and Korea. In North America and Europe the species is very successful and has been classified as invasive in several countries.

A member of the family Polygonaceae, Japanese knotweed has hollow stems with distinct raised nodes that give it the appearance of bamboo, though it is not closely related. While stems may reach a maximum height of 3–4 m each growing season, it is typical to see much smaller plants in places where they sprout through cracks in the pavement or are repeatedly cut down. The leaves are broad oval with a truncated base, 7–14 cm long and 5–12 cm broad, with an entire margin. The flowers are small, creamy white, produced in erect racemes 6–15 cm long in late summer and early autumn.

Closely related species include giant knotweed (Fallopia sachalinensis, syn. Polygonum sachalinense) and Russian vine (Fallopia baldschuanica, syn. Polygonum aubertii, Polygonum baldschuanicum).

Other English names for Japanese knotweed include fleeceflower, Himalayan fleece vine, monkeyweed, Huzhang (Chinese: 虎杖; pinyin: Hǔzhàng), Hancock's curse, elephant ears, pea shooters, donkey rhubarb (although it is not a rhubarb), sally rhubarb, Japanese bamboo, American bamboo, and Mexican bamboo (though it is not a bamboo). In Japanese, the name is "itadori" (usually written in katakana). There are also regional names, and it is sometimes confused with sorrel.

Japanese Knotweed is a commercial source of resveratrol supplements. Hu Zhang root extract is a traditional Chinese medicinal treatment.

Invasive species

Old stems remain in place as new growth appears

In the U.S.A. and Europe, Japanese knotweed is widely considered an invasive species or weed.[1] It is listed by the World Conservation Union as one of the world's 100 worst invasive species.[2] In Britain it was made illegal to spread Japanese knotweed under the Wildlife and Countryside Act 1981. It is also classed as 'controlled waste' under the Environmental Protection Act 1990. This requires disposal at licensed landfill sites.[3] It is a frequent colonizer of temperate riparian ecosystems, roadsides and waste places. It forms thick, dense colonies that completely crowd out any other herbaceous species and is now considered one of the worst invasive exotics in parts of the eastern United States. The success of the species has been partially attributed to its tolerance of a very wide range of soil types, pH and salinity.[4] Its rhizomes can survive temperatures of −35 °C (−31 °F) and can extend 7 metres (23 ft) horizontally and 3 metres (9.8 ft) deep, making removal by excavation extremely difficult. The plant is also resilient to cutting, vigorously re-sprouting from the roots. The most effective method of control is by herbicide application close to the flowering stage in late summer or autumn. In some cases it is possible to eradicate Japanese knotweed in one growing season using only herbicides.[5] Trials in the Queen Charlotte Islands (Haida Gwaii) of British Columbia using sea water sprayed on the foliage have demonstrated promising results, which may prove to be a viable option for eradication where concerns over herbicide application are too great.[citation needed]

It can be found in 39 of the 50 United States (PUSDA) and in six provinces in Canada. The species is also common in Europe. In the U.K. it was made illegal to spread Japanese knotweed by the Wildlife and Countryside Act 1981. In the U.S.A. it is listed as an invasive weed in Ohio, Vermont, Virginia, New York, Alaska, Pennsylvania, Oregon and Washington state.[6]

Two biological pest control agents that show promise in the control of the plant are the psyllid Aphalara itadori and a leaf spot fungus from genus Mycosphaerella.[7]

Uses

Japanese knotweed flowers are valued by some beekeepers as an important source of nectar for honeybees, at a time of year when little else is flowering. Japanese knotweed yields a monofloral honey, usually called bamboo honey by northeastern U.S. beekeepers, like a mild-flavored version of buckwheat honey (a related plant also in the Polygonaceae).

Erect inflorescence

The young stems are edible as a spring vegetable, with a flavor similar to mild rhubarb. In some locations, semi-cultivating Japanese knotweed for food has been used as a means of controlling knotweed populations that invade sensitive wetland areas and drive out the native vegetation.[8] Some caution should be exercised when consuming this plant because of it contains oxalic acid, which may aggravate conditions such as rheumatism, arthritis, gout, kidney stones or hyperacidity.[9]

Both Japanese knotweed and giant knotweed are important concentrated sources of resveratrol, replacing grape byproducts.[10] Many large supplement sources of resveratrol now use Japanese knotweed and use its scientific name in the supplement labels.[11] The plant is useful because of its year-round growth and robustness in different climates.[12]

Japanese knotweed is a concentrated source of emodin, used as a nutritional supplement to regulate bowel motility. The roots of Japanese knotweed are used in traditional Chinese and Japanese herbal medicines as a natural laxative. The active principle responsible for the laxative effect is emodin, present in its natural form as a complex of its analogs. Emodin has a mild laxative effect in doses of 20 to 50 mg per day.[13]

Elimination

Japanese knotweed has a large underground network of roots (rhizomes). To eradicate the plant the roots need to be killed. Picking the right herbicide is essential, as it must travel through the plant and into the root system below. Glyphosate is the best active ingredient in herbicide for use on Japanese knotweed as it is ’systemic’. It penetrates through the whole plant and travels to the roots. Glyphosate is available under several trade names - all label the product as a "weed and grass killer". Commercial Glyphosate concentrates contain approximately 20%-40% Glyphosate; the balance is mostly water. Such concentrates need to be diluted in water.

The most effective spraying solution contains about 5%-10% Glyphosate in water. (To make a 5% solution from a 40% concentrate mix 1 part concentrate with 7 parts water.) Ready-to-use solutions that contain less than 5% Glyphosate are too weak and do not work. A small amount of liquid dish-washing detergent can be added to improve wetting of the leaves. If possible, both sides of the leaves should be sprayed until they are completely wet. It takes about 3 weeks for most of the plants to dry. After 3 weeks, all remaining plants should be sprayed again. This process needs to be continued until all the plants dry out.

The US federal government will come and spray japanese knotweed for no charge in many areas under the invasive species act. Local county extension agencies can be contacted for more details.

References

File:Knotweed.JPG
Detail of the stalk
  1. ^ Biological control of invasive plants in the Eastern United States
  2. ^ IUCN Global Invasive Species Database
  3. ^ [1]
  4. ^ Japanese Knotweed
  5. ^ Single Season Eradication of Japanese Knotweed
  6. ^ USDA weed profile for Japanese knotweed
  7. ^ Morelle, R. Alien invaders hit the UK. BBC News October 13, 2008.
  8. ^ Pilot project of Bionic Knotweed Control in Wiesbaden, Germany
  9. ^ [2]
  10. ^ Resveratrol Purity
  11. ^ Resveratrol
  12. ^ Pest Diagnostic Unit, University of Guelph
  13. ^ GMP Natraceuticals
Wikimedia Commons has media related to Fallopia japonica.
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