Sunday, January 19, 2014

Japanese Knotweed: The Concrete-Busting Superweed

During the 2013 GPIP Invasive Plant Walk, our guest speaker Donna Ellis from the UCONN Extension Service cited Japanese Knotweed as the greatest invasive plant threat in our state. That left many of us scratching our heads because every day we see incredible tree damage all around us caused by oriental bittersweet. Donna graciously let us have our say (or perhaps responded to our chanting "oriental bittersweet!!") and wisely conceded the point in the interest of getting out of town alive.

After discovering several videos of Japanese Knotweed damage in the UK, where the infestation is a number of years ahead of us, maybe we should grudgingly agree to a tie as to which invasive plant is the bigger bad actor. Oriental bittersweet may cause far more dramatic and visible tree destruction, but as a future threat Japanese Knotweed is making huge strides and is well poised to do significant property damage.

Japanese Knotweed grows rapidly, up to 3" a day, and is capable of splitting concrete slabs. It grows up through asphalt and is almost impossible to eradicate because it can grow 8 or more feet deep. In its native habitat it grows through volcanic rock (that's how tough this stuff is). The rhizomes can be lie dormant for up to 20 years. If you dig them up and throw them away, a section as long as as 2" can take root and start a new plant. Some experts call it "the terrorist of the weed world."

Matters have become so dire in the UK that it has become a criminal offense to cause the spread of Japanese Knotweed. Violators are subject to stiff fines and up to 6 months in jail. The bill for Japanese Knotweed infestation clean-up at the 2012 Olympics site was in the tens of millions of dollars; without full eradication the weed could do extensive damage to stadiums and other structures at the site. Experiments are underway to determine if importing aphalara itadori (an insect native to Japan that eats the sap of Japanese Knotweed plants) could help slow infestation in the UK.

Do we have Japanese Knotweed in Glastonbury? Absolutely and plenty of it. See photos at the GPIP photo library. Taking action now can make all the difference. Don't wait until the task becomes impossible or the cost of property and infrastructure damage gets our attention. Let's not let the UK (video below) be a preview of our future.

The video below deals with eradication via stem
injection and is at a fairly high technical level: