Please identify this alien beast & the weapon to destroy it!

swarminaMay 4, 2013

This plant grew in a sunny bed that we cleared that had a covering of English ivy two summers ago. Initially I thought there were stones in the soil at shovel level but found that actually this was a root of a plant had fibrous,thick roots that were sometimes the thickness of fireplace wood! These plants grow as tall as several feet if left unmoved. The sprouts are reddish with white stems when newly growing from the dirt. Last year we weeded and dug down 1.5 feet and pulled out tons of the woody roots and laid down cardboard and mulch over, thinking we had done a thorough job getting rid of this nasty stuff. Well 4 weeks late the stuff started sprouting up again. Our work seems to have encouraged it. I am pretty adverse to chemicals. Will black plastic over the bed do it? Any thoughts on what it is and a good way to eradicate it? Thanks in advance!


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Did it flower last year? It really looks like Japanese bamboo - Polygonum cuspidatum - which is one of the nastiest invasive plants ever brought to this continent (or any other, for that matter). Check some images on the 'net (use the latin name) and see if it matches what you've got.

    Bookmark   May 4, 2013 at 7:35PM
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I never let it flower, but that does look similar in some photos. How do I get rid of it?

    Bookmark   May 4, 2013 at 11:05PM
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Although often call "Japanese Bamboo", this plant is not a bamboo. Japanese Knotweed is an aggressive, invasive plant that can be difficult to remove due to the root system it does establish. Denying the roots food, keeping top growth cut down, can eventually starve them so they die but digging the roots up is much quicker although harder work. Plant poisons can help, but those do have envrionmental affects that probably are not good for our planet.

Here is a link that might be useful: Japanese Knotweed

    Bookmark   May 5, 2013 at 6:54AM
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This just sounds hideously bad... :(

    Bookmark   May 5, 2013 at 2:11PM
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It is hideously bad, but thank God that you caught it before it got immeasurably worse. It is going to be a goodly amount of work, but if you keep at it, you can get rid of it.

What I've seen on various webpages leads me to think that it will take a combination of manual labor and herbicide. I agree with Kimmsr that indiscriminate herbicide use is to be avoided, but there are invasive plants, of which this is one, that cannot be controlled without herbicide, which must be used wisely. As I understand it, the plant can resprout from the smallest piece of root left in the ground when it's dug up - easy to see why physical/mechanical means aren't enough.

There is a lot of really good, reliable information on the net about invasives; there is also a lot of crap. Below is a link to the webpage of the National Arboretum, with lots of links to agencies, including at the state level, that deal with invasives, and what you've got is one of the biggies, so there should be a lot of information on getting rid of it. Your county or state agencies could be a lot of help in this.

You have already done the really important parts - you didn't let it flower, and you have identified it. I wish you a strong back, willing help, and all the success you could wish for in this and all your gardening.

Here is a link that might be useful: Page on invasive plants, w/ lots of links

    Bookmark   May 5, 2013 at 7:53PM
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