Where is japanese knotweed from

Here's how you know. View all resources. Scientific Name:. Fallopia japonica Houtt. Ronse Decr. Common Name:. Japanese knotweed, fleeceflower, Mexican bamboo, huzhang.

Native To:. Date of U. Means of Introduction:. Introduced as an ornamental Stone Crowds out native species Stone University of Georgia. Center for Invasive Species and Ecosystem Health. Provides state, county, point and GIS data. Maps can be downloaded and shared. Google Images - Japanese Knotweed. YouTube - Japanese Knotweed. YouTube; University Nebraska - Lincoln. Ohio Invasive Plants Council. See also: Invasive Plants of Ohio for worst invasive plant species identified in Ohio's natural areas.

Priority Species: Japanese Knotweed. Washington State Recreation and Conservation Office. Washington Invasive Species Council. Southeast Exotic Pest Plant Council. University of Alaska - Anchorage. Alaska Center for Conservation Science. See also: Non-Native Plant Species List for additional factsheets species biographies and species risk assessment reports of non-native species present in Alaska and also non-native species currently not recorded in Alaska potential invasives.

Global Invasive Species Database - Fallopia japonica herb, shrub. Species Survival Commission. Invasive Species Specialist Group. Invaders Factsheet: Japanese Knotweed. Invasive Species Compendium - Fallopia japonica. CAB International. Japanese Knotweed Alliance. CABI Bioscience.

New York Invasive Species Clearinghouse. Non-native Species Information: Japanese Knotweed. Weeds Australia - Japanese Knotweed Fallopia japonica. Rocky Mountain Research Station. Fire Sciences Laboratory. National Plant Data Center. National Plant Germplasm System - Reynoutria japonica. Invasive Plants - Japanese Knotweed. Cornwall County Council United Kingdom. Division of Plant Industry. Michigan Natural Features Inventory.

See also: Best Control Practice Guides for more guides. Indiana Department of Natural Resources. We recommend glyphosate, a nonselective herbicide available as aquatic-labeled products for use in or near water. Glyphosate is effective, has low toxicity to nontarget organisms, has no soil activity, and is relatively inexpensive.

The herbicide imazapyr e. Broadleaf herbicides such as triclopyr or 2,4-D provide significant foliar injury but have limited effect on the rhizome system. Mixing glyphosate with other herbicides makes sense if knotweed is not your only target during spray operations.

Combinations with triclopyr or imazapyr provide a broader species spectrum and do not reduce activity against knotweed. The management calendar for knotweed emphasizes late season applications of the herbicide glyphosate to maximize injury to the rhizomes and waiting at least eight weeks after cutting to apply herbicide. Prescriptions for controlling knotweed stress proper timing of operations to maximize injury to rhizomes.

Improper timing will result in treatments that provide "topkill" shoot injury but little net effect. Product names reflect the current Pennsylvania state herbicide contract; additional brands with the same active ingredients are available.

All species of knotweed found in the United States produce edible young shoots in spring. Knotweed honey is a popular monoculture honey, as its fragrant, nectar-rich blossoms are a favorite of our nonnative honey bee Apis mellifera. In its native Asia, knotweed has many applications in traditional herbal medicine. While these human uses are often raised in argument against controlling Japanese and other knotweeds, none outweigh the consequences of unchecked knotweed infestation. Knotweed infestations result in decreased biodiversity in both plant and animal communities, degraded water quality, and damage to human infrastructure such as road and bridge foundations.

These widespread and highly negative effects should be considered alongside any argument for its overall value. Let's Stay Connected. By entering your email, you consent to receive communications from Penn State Extension. View our privacy policy. Thank you for your submission! Home Japanese Knotweed. Japanese Knotweed. Japanese knotweed Fallopia japonica is an invasive perennial and noxious weed in PA.

This article will assist with identification and provides recommendations for control, including a management calendar and treatment and timing table. Photo credit: Dave Jackson. Background Japanese knotweed Fallopia japonica syn. Description Size Growing up to 11 feet tall, knotweed can spread horizontally via an extensive network of underground rhizomes, along which many shoots will sprout.

Stems Superficially resembling bamboo, its jointed, hollow stem has many red or purple nodes where the leaves are attached. Leaves Many alternately arranged, spade- or heart-shaped leaves emerge from nodes along the stem, though lower leaves are often shed as the plant grows. Flowers In late summer, white or pale green flower clusters sprout from the nodes. New shoots Emerging in early spring, the young growth is especially bright red or purple and tipped with many furled leaves that are distinctly triangular.

Photo by Dave Jackson Cut stem showing hollow interior between nodes. Photo by Dave Jackson Giant knotweed leaf shape with curved base. Photo by Dave Jackson Japanese knotweed leaf shape showing squared base and zigzag stem growth.

Photo by Dave Jackson Stem showing nodes. Photo by Dave Jackson Young knotweed sprout. Photo by Dave Jackson Monoculture forming on streamside.

Photo by Dave Jackson Look-alikes Knotweed is often confused with bamboo subfamily Bambusoideae , another invasive plant. Dispersal The key to Japanese knotweed's success is its ability to spread vegetatively through its root system.

Site This plant thrives on most sites that are at least seasonally wet. Control The primary objective in controlling Japanese knotweed is eliminating the rhizome system. Management Calendar The management calendar for knotweed emphasizes late season applications of the herbicide glyphosate to maximize injury to the rhizomes and waiting at least eight weeks after cutting to apply herbicide.

Treatment and Timing Prescriptions for controlling knotweed stress proper timing of operations to maximize injury to rhizomes. This is a particular advantage in riparian settings, where full-size knotweed will hang over the water, making it impossible to treat without contacting the water with herbicide solution. The product rates differ because the glyphosate concentration differs between products.

Applications of Aquaneat will require an additional surfactant e. No additional surfactant is needed with Glyphomate If you work at the early end of the operational window, you can make a touch-up application later in the season before a killing frost. Use this treatment for both initial control and follow-up maintenance applications.

For high-volume spray-to-wet applications, mix on a gallon-per-acre basis e. For all treatments, be sure to calibrate your sprayer. Human Use All species of knotweed found in the United States produce edible young shoots in spring. David R. Sarah Wurzbacher. Art Gover. Skylure Templeton. Why do we need this? Entering your postal code will help us provide news or event updates for your area.