It’s taking over. Quite simply taking over. More and more areas are being devoured. Along roads I drive, in diverse areas I hike Japanese Knotweed is on its grim path to taking over virtually everything.
The photo, for example, shows young sprouts growing in running water, which I didn’t even know they were capable of, just one more example of their ability to colonize, seemingly, EVERYWHERE.
Take a walk along the banks of the Susquehanna River in the Kirby Park natural area and you’ll see how knotweed has claimed massive amounts of the riverbank. And every year it gets worse.
Knotweed was introduced to the U.S. from Japan as an ornamental, for fodder and erosion control in the late 1800s. It now occurs in 40 states.
It spreads quickly, forming dense stands that exclude native vegetation. On riverbanks, it easily survives severe floods and rapidly recolonizes, usurping the role of native species.
This is one very bad boy: It can grow through walls, tarmac and concrete and can grow by up to four inches a day during the summer. It is listed as one of the world’s 100 worst invasive species. Mortgage lenders have even been known to refuse mortgages on properties that are affected by Japanese knotweed.
It is tremendously difficult to control, much less eradicate. As Wallace Kaufman said in “Invasive Plants,” “Seedlings may be cut or pulled to exhaust the rhizome and kill the plants. This may take up to 10 years in a well-established stand.”