Japanese Knotweed-Japanese Bamboo - Cornell Cooperative ...
CORNELL COOPERATIVE EXTENSION OF ONEIDA COUNTY
121 Second Street Oriskany, NY 13424-9799 (315) 736-3394 or (315) 337-2531 FAX: (315) 736-2580
Japanese Knotweed Prepared by John Condzella and Leslie A. Weston, Landscape Weed Management Team Japanese knotweed (Polygonum cuspidatum) is a native of Asia and was first introduced to England in the early 19th century as an ornamental. It was later introduced into the United States for erosion control and also on Long Island as an estate-grown ornamental due to its attractive foliage and cream colored inflorescences. It is a very aggressive weed that often crowds out the surrounding vegetation and is difficult to manage due to it has extremely dynamic rhizomes that form a deep, dense mat. Japanese knotweed is sometimes referred to as Japanese bamboo since the stems can resemble a bamboo shoot, however the leaves are very distinct and heart shaped, and are certainly not grasslike. Other common names of Japanese knotweed include fleeceflower, Mexican bamboo, and huzhang. Description: Japanese knotweed is a rhizomatous perennial, with several reddish-brown, freely branched stems. It is fast-growing, aggressive, Photo by J. K. Randall and often appears in dense clumps in which little or no competing vegetation survives, and reaches heights between 4 to 8 feet tall. The stem is hollow and jointed, hence the comparison to bamboo. The leaves are alternate, broadly eggshaped, and 3 to 6 inches in length. The plant is dioecious, so male and female plants both produce cream colored flowers that vary slightly in appearance. Flowers appear in late summer and are found in erect clusters 4 to 5 inches long arising from the leaf axils. Reproduction: Japanese knotweed spreads primarily via rhizomes, from which young reddish shoots emerge in the early spring. The plant can produce viable seeds, particularly if it hybridizes with other closely related species; however the majority of reproduction will occur from the mechanical distribution of rhizome pieces which resprout. Habitat/distribution: Japanese knotweed, introducedChanges from Japan as This publication contains pesticide recommendations. in pesticide regulations occur constantly, some anmaterials ornamental has become a weed of the roadside as well as mentioned may no longer be available, and some uses may no longer be legal. All pesticides distributed, diverse landscapes. It can beregistered found in moist, sold, and/or applied in Newmost Yorkcommonly State must be with the New York Statein Department Variation size and shapeof ofEnvironmental leaves of unmanaged areas including riverbanks and riparian Photo Conservation (DEC). Questions concerning the legalitysites, and/orsodded registration Japanese status forknotweed. pesticide useby inCameron New York H. Douglass. storm drains and ditches, roadsides and unkempt gardens. State should be directed to the appropriate Cornell Cooperative Extension Specialist or your regional DEC office. Japanese knotweed is BEFORE common throughout U.S. and tends to READ THE LABEL APPLYINGthe ANY PESTICIDE. flourish on moist, well-drained, nutrient-rich soil, especially on shaded banks. Recently, it has appeared more frequently along sunny, dry roadside locations, suggesting that the plant is adapting to diverse Updated 2008 environments. Source:
Helping You Put Knowledge to Work Cornell Cooperative Extension provides equal program and employment opportunities. NYS College of Agriculture and Life Sciences, NYS College of Human Ecology, and NYS College of Veterinary Medicine at Cornell University, Cooperative Extension associations, county governing bodies, and U.S. Department of Agriculture, cooperating.
Control methods: The best suggested control for Japanese knotweed is the prevention of establishment, as it is very difficult to eradicate once established. The plant should be destroyed as soon as it appears by cutting, chopping, herbicide treatment and subsequent disposal of any cut vegetation. The growth of the rhizomes can be slowed by cutting back the stalks as much as three times during the growing season, reducing rhizome reserves for successful plant generation. After cutting back the foliage, an application of a glyphosatebased herbicide has been discovered Photographer unknown to be particularly effective. Glyphosate (Round Up) application should be performed in late summer through early fall when the translocation of herbicides to the plants root system is maximal. In order to be sure that the rhizomes have been thoroughly eradicated, a few years of treatments may be necessary. One technique that has proven effective for managing small stands of Japanese knotweed is the application of concentrated glyphosate directly to the plant root system by injection into the hollow stem at approximately the 3rd stem node or below. This syringe injection technique is labeled in New York State with Aquamaster herbicide, and has proven effective with small managed stands. Other herbicides have proven ineffective for control due to limited translocation into the rhizomes. Not surprisingly, the rhizomes are difficult to remove by hand digging and can penetrate soils up to a depth of 10 feet or more after a year of establishment. Interestingly, the rhizomes have been shown to be a potent source of the antioxidant and cancer suppressive compound resveratrol. Perhaps new uses for this plant can be deduced, based on the need for easily extractable resveratrol sources. Additional references: Weeds of the Northeast. Authored by Uva, R., J. Neal and J. DiTomaso. Cornell University Press. Weston, L. A., J. N. Barney and A. DiTommaso. 2005. A review of the biology and ecology of three invasive perennials in New York State including Japanese knotweed, mugwort and pale or black swallowwort species. Plant and Soil. 277:53-69. This publication may contain pesticide recommendations. Changes in pesticide regulations occur constantly, some materials mentioned may no longer be available, and some uses may no longer be legal. All pesticides distributed, sold, and/or applied in New York State must be registered with the New York State Department of Environmental Conservation (DEC). Questions concerning the legality and/or registration status for pesticide use in New York State should be directed to the appropriate Cornell Cooperative Extension Specialist or your regional DEC office. READ THE LABEL BEFORE APPLYING ANY PESTICIDE. DISCLAIMER: Please note that neither Cornell Cooperative Extension of Oneida County nor any representative thereof makes any representation of any warranty, express or implied, of any particular result or application of the information provided by us or regarding any product. If a product is involved, it is the sole responsibility of the User to read and follow all product labeling instructions and to check with the manufacturer or supplier for the most recent information. Nothing contained in this information should be interpreted as an express or implied endorsement of any particular product or criticism of unnamed products. With respect to any information on pest management, the User is responsible for obtaining the most up-to-date pest management information. The information we provide is no substitute for pesticide labeling. The User is solely responsible for reading and following the manufacturer’s labeling and instructions. (October 2009) Updated 2012 lsk13
121 Second Street Oriskany, NY 13424-9799 (315) 736-3394 or (315) 337-2531 FAX: (315) 736-2580
Japanese Knotweed Prepared by John Condzella and Leslie A. Weston, Landscape Weed Management Team Japanese knotweed (Polygonum cuspidatum) is a native of Asia and was first introduced to England in the early 19th century as an ornamental. It was later introduced into the United States for erosion control and also on Long Island as an estate-grown ornamental due to its attractive foliage and cream colored inflorescences. It is a very aggressive weed that often crowds out the surrounding vegetation and is difficult to manage due to it has extremely dynamic rhizomes that form a deep, dense mat. Japanese knotweed is sometimes referred to as Japanese bamboo since the stems can resemble a bamboo shoot, however the leaves are very distinct and heart shaped, and are certainly not grasslike. Other common names of Japanese knotweed include fleeceflower, Mexican bamboo, and huzhang. Description: Japanese knotweed is a rhizomatous perennial, with several reddish-brown, freely branched stems. It is fast-growing, aggressive, Photo by J. K. Randall and often appears in dense clumps in which little or no competing vegetation survives, and reaches heights between 4 to 8 feet tall. The stem is hollow and jointed, hence the comparison to bamboo. The leaves are alternate, broadly eggshaped, and 3 to 6 inches in length. The plant is dioecious, so male and female plants both produce cream colored flowers that vary slightly in appearance. Flowers appear in late summer and are found in erect clusters 4 to 5 inches long arising from the leaf axils. Reproduction: Japanese knotweed spreads primarily via rhizomes, from which young reddish shoots emerge in the early spring. The plant can produce viable seeds, particularly if it hybridizes with other closely related species; however the majority of reproduction will occur from the mechanical distribution of rhizome pieces which resprout. Habitat/distribution: Japanese knotweed, introducedChanges from Japan as This publication contains pesticide recommendations. in pesticide regulations occur constantly, some anmaterials ornamental has become a weed of the roadside as well as mentioned may no longer be available, and some uses may no longer be legal. All pesticides distributed, diverse landscapes. It can beregistered found in moist, sold, and/or applied in Newmost Yorkcommonly State must be with the New York Statein Department Variation size and shapeof ofEnvironmental leaves of unmanaged areas including riverbanks and riparian Photo Conservation (DEC). Questions concerning the legalitysites, and/orsodded registration Japanese status forknotweed. pesticide useby inCameron New York H. Douglass. storm drains and ditches, roadsides and unkempt gardens. State should be directed to the appropriate Cornell Cooperative Extension Specialist or your regional DEC office. Japanese knotweed is BEFORE common throughout U.S. and tends to READ THE LABEL APPLYINGthe ANY PESTICIDE. flourish on moist, well-drained, nutrient-rich soil, especially on shaded banks. Recently, it has appeared more frequently along sunny, dry roadside locations, suggesting that the plant is adapting to diverse Updated 2008 environments. Source:
Helping You Put Knowledge to Work Cornell Cooperative Extension provides equal program and employment opportunities. NYS College of Agriculture and Life Sciences, NYS College of Human Ecology, and NYS College of Veterinary Medicine at Cornell University, Cooperative Extension associations, county governing bodies, and U.S. Department of Agriculture, cooperating.
Control methods: The best suggested control for Japanese knotweed is the prevention of establishment, as it is very difficult to eradicate once established. The plant should be destroyed as soon as it appears by cutting, chopping, herbicide treatment and subsequent disposal of any cut vegetation. The growth of the rhizomes can be slowed by cutting back the stalks as much as three times during the growing season, reducing rhizome reserves for successful plant generation. After cutting back the foliage, an application of a glyphosatebased herbicide has been discovered Photographer unknown to be particularly effective. Glyphosate (Round Up) application should be performed in late summer through early fall when the translocation of herbicides to the plants root system is maximal. In order to be sure that the rhizomes have been thoroughly eradicated, a few years of treatments may be necessary. One technique that has proven effective for managing small stands of Japanese knotweed is the application of concentrated glyphosate directly to the plant root system by injection into the hollow stem at approximately the 3rd stem node or below. This syringe injection technique is labeled in New York State with Aquamaster herbicide, and has proven effective with small managed stands. Other herbicides have proven ineffective for control due to limited translocation into the rhizomes. Not surprisingly, the rhizomes are difficult to remove by hand digging and can penetrate soils up to a depth of 10 feet or more after a year of establishment. Interestingly, the rhizomes have been shown to be a potent source of the antioxidant and cancer suppressive compound resveratrol. Perhaps new uses for this plant can be deduced, based on the need for easily extractable resveratrol sources. Additional references: Weeds of the Northeast. Authored by Uva, R., J. Neal and J. DiTomaso. Cornell University Press. Weston, L. A., J. N. Barney and A. DiTommaso. 2005. A review of the biology and ecology of three invasive perennials in New York State including Japanese knotweed, mugwort and pale or black swallowwort species. Plant and Soil. 277:53-69. This publication may contain pesticide recommendations. Changes in pesticide regulations occur constantly, some materials mentioned may no longer be available, and some uses may no longer be legal. All pesticides distributed, sold, and/or applied in New York State must be registered with the New York State Department of Environmental Conservation (DEC). Questions concerning the legality and/or registration status for pesticide use in New York State should be directed to the appropriate Cornell Cooperative Extension Specialist or your regional DEC office. READ THE LABEL BEFORE APPLYING ANY PESTICIDE. DISCLAIMER: Please note that neither Cornell Cooperative Extension of Oneida County nor any representative thereof makes any representation of any warranty, express or implied, of any particular result or application of the information provided by us or regarding any product. If a product is involved, it is the sole responsibility of the User to read and follow all product labeling instructions and to check with the manufacturer or supplier for the most recent information. Nothing contained in this information should be interpreted as an express or implied endorsement of any particular product or criticism of unnamed products. With respect to any information on pest management, the User is responsible for obtaining the most up-to-date pest management information. The information we provide is no substitute for pesticide labeling. The User is solely responsible for reading and following the manufacturer’s labeling and instructions. (October 2009) Updated 2012 lsk13
