The flowers are arranged in spikes near the end of the stems that are small, numerous and creamy white in color. This network allows it to spread to new areas even as it is being attacked mechani-cally. To choke out a mature stand of Japanese knotweed: Cut all of the Japanese knotweed plants down to the ground. Japanese knotweed can also be effectively controlled with herbicides, but timing is key. Control. In the spring and throughout the growing season, sugars and nutrients move upward from the roots to … The flow of nutrients in Japanese knotweed is in one direction. It grows to heights of , and the roots can be twice that deep. Japanese Knotweed Brochure . Successful control of Japanese knotweed requires multiple applications the first season, and multiple seasons of control. Use the lawnmower at its lowest setting and mow the weeds to the ground. Japanese knotweed has come a long way since Philipp Franz von Siebold, the doctor-in-residence for the Dutch at Nagasaki, brought it to the Utrecht plant fair in the Netherlands in the 1840s. The primary objective in controlling Japanese knotweed is eliminating the rhizome … The stems have a fine white coating that rubs off easily. Control efforts must target knotweed’s massive underground system of rhizomes. Remove as many sharp objects from the area as possible, including the cut stumps. Doing this weekly will weaken and kill the plants. Japanese knotweed is a Class B Noxious Weed in Washington, first listed in 1995. It was introduced to the United Kingdom from Japan as an ornamental in 1825 and from there to North America in the late 1800s. Mechanical methods alone will not effectively control large Japanese knotweed populations and may make them worse. Less risky to the environment, as the injected herbicide has no effect on the surrounding vegetation and is … Prevent a Japanese knotweed infestation by mowing the weed area every week. Japanese Knotweed Biological Control Japanese knotweed (Fallopia japonica) is an herbaceous perennial native to Eastern Asia. DRWA has produced, with the help of the Massachusetts Environmental Trust and CopyCat Print Shop of Greenfield, a brochure (in PDF format) that explains the identification and ecology of Japanese knotweed and the impacts of the plant on the environment. Spread a covering over the area such that the ground … Japanese knotweed is considered one of the most damaging weeds in the United Invasive Species - (Fallopia japonica) Prohibited in Michigan Japanese knotweed is a perennial shrub that can grow from 3 - 10 feet high. Japanese knotweed is an invasive ornamental plant that can be tough to remove. Plant Control: Apply a glyphosate herbicide in combination with cutting. Control and eliminate this invasive weed by using the right Japanese knotweed treatment and … It has hollow stalks that are persistent through the winter and look similar to bamboo. A late summer application of glyphosate is the key to … In comparison to native streamside vegetation, Japanese knotweed provides poor erosion control, and its presence gradually degrades aquatic habitat and water quality. Japanese knotweed absorbs the glyphosate into the rhizome with a faster absorbency rate than that of foliar spraying. Stem injection involves injecting a concentrate of glyphosate herbicide into each cane of the weed using specialist equipment specifically designed in the treatment of Japanese knotweed. If the Japanese Knotweed is in an aquatic habitat, you will need to use a product such as Rodeo or AquaNeat. 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