Story and photo by Gabrielle L. Wheeler
Every summer, I watch the farmer down the road fight with a tall, large-leafed weed that grows out by the guard rail. To try to get rid of it, he has done everything short of burning it – and that is probably only because there is a wooden light pole in the middle of the clump. Unfortunately, I know what avails him, and no matter how many times he dumps herbicide on his foe, or simply mows it, he will not conquer. Unfortunately, he is probably propagating its spread instead.
The farmer is fighting Japanese knotweed (Fallopia japonica), an invasive perennial with heart-shaped leaves and a stem that resembles bamboo. It grows in thick clumps which get to be as tall as 15 feet. His leafy enemy is unable to be destroyed because underground, each shoot of the weed is connected by one giant, knotty root, from which the plant gets its name.
According to the NYS Invasive Species Information webpage, Japanese knotweed was introduced into the US in the late-1800s. During its history in the United States, Japanese knotweed has been sold as an ornamental and used as an erosion control option, promoting its colonization across most of the country. By the mid-1930s, it was already being viewed as a pest. As with nearly any invasive plant, Japanese knotweed thrives in disturbed areas and will then crowd out native flora, forming thick stands that are hard to remove. In the United Kingdom, because of its knotty root which can disturb foundations and its ability to grow almost 4 inches a day, Japanese knotweed is reported to decrease a property’s value by 50%.
Removal is possible, though it is recommended it be done with professional guidance. Options include physically removing the plants, most easy at initial colonization stage. Digging out the root system is also possible. Any plant material should be bagged for disposal to prevent propagation as Japanese knotweed is extremely adept at re-establishing itself from the tiniest clipping of live plant material. Chemical control is also an option.
If you have Japanese knotweed on your property that you would like to get rid of, check with your local environmental control agency or Cornell Cooperative Extension to find out what chemicals you can use in your region or how to dispose of bagged plant material. Maybe I will stop some day and suggest the farmer to do the same.