Japanese Knotweed: Problem #1

Japanese Knotweed
Japanese Knotweed taking over a meadow

We knew that Japanese Knotweed was particularly awful as an invasive, up there with bamboo, kudzu, wisteria, phragmites, oriental bittersweet, porcelain berry, and English Ivy, but after reading this article out of the UK, it may well be that Japanese Knotweed could be the worst of the lot.

Japanese Knotweed May Already Be In Your Yard
  1. Japanese Knotweed is nearly impossible to eradicate. It’s roots can reach down 9 feet, and it can re-sprout from the tiniest portion of root, even years later.
  2. It’s highly destructive. It evolved as a pioneer species around volcanos in Japan, their roots growing through the hard rock of a recent lava flow. Its roots do the same to concrete.
  3. It’s economically disastrous. Japanese Knotweed is in the process of consuming Fire Island in Cherry Grove, and is well established on many of our waterways and in abandoned lots. Left unchecked, it will overrun local nature and crack your foundation. It is already affecting property values in the UK.

Japanese Knotweed: What Can We Do?

So what do we on Long Island do now? We need to inventory where there are stands of Japanese Knotweed, so we can at least begin to cut them back and keep them from spreading further. It’s on everyone’s property — in our parks, our yards, along our roads. Not to be an alarmist, but it is indeed time to sound the alarm.

As this fascinating — and terrifying — article from the UK makes clear, an entire island under threat, and there is no real solution now. We can only hope to contain it, and even that is going to take a monumental effort. That unfortunately reflects Long Island’s current situation as well:

The Race To Kill The World’s Most Invasive Weed

It’s a fascinating read. It turns out, it was largely the actions of one enterprising Victorian gardener that brought Japanese Knotweed to England. He became an importer of exotic plants, and so it was throughout the last couple of hundred years. Plants were brought in from all over the place, and an industry flourished. Globalization has put a Japanese Maple in every suburban yard it seems.

That is in fact the rule today — most plants for sale are imported, or non-native. People have a tough time finding natives. Most of the time, the non-natives do no worse than take up space where native plants would otherwise grow, an opportunity to create local nature.

But then we have something pernicious, like Japanese Knotweed, and it is in the process of causing enormous damage here. Just the damage it stands to cause on Fire Island’s National Seashore is staggering. Arguably, federal funds are called for here.

Japanese Knotweed in Springtime

It will take persistent hard labor over a decade to contain. All the other invasive plants now overwhelming Long Island could be addressed at the same time of course.

Are we ready for that? Do we have a choice? If you know of a stand of Japanese Knotweed, drop info in it in your comments or email us at info@longislandconservancy.org. We need to start to get our arms around this for starters.


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