Knotweed eradication, part eight

April 2010

We’ve been battling invasive Japanese knotweed at Henbogle since we arrived.  Removal was complicated by another invasive, a multiflora rose, growing in the middle of the knotweed.  We had tried cutting back the knotweed and treating it with RoundUp, which definitely slowed the plants down, but didn’t kill them.  So we decided to try mowing.

Former knotwwed jungle. Downed logs mark the propoerty line

Starting over yet again, in 2010 we decided we needed to kill off the multiflora rose.  Not an easy task, it is very successful at colonizing and we could not get the all the tenacious roots out of the ground.  We killed off the many plants as best we could and kept trimming back any new shoots.  It finally seemed to die, and this week Dan was able to remove most of the remaining stumps/roots with a grub axe.  While he was at it, he pulled large clumps of the knotweed roots, too, generating 2 huge truckloads of debris.  We won’t be composting this!

He then raked and smoothed the soil, and we added grass seed, watered, and mulched with some aged straw hen bedding.  He chopped the straw with the lawn mower and then we spread it over the seed and watered again.

I hope this will allow us to keep this area mowed, and will knock back the knotweed significantly.  Between the root removal and frequent mowing I am hoping we can be rid of the evil stuff.  We have to be vigilant in keeping it at bay, because it is so vigorous that the tiniest foothold id enough to keep it going.  If we fail, the next step is to call a professional landscaper to spray it with something horrible.  I’d greatly prefer to avoid this scenario, but we’ve been working on removal of the knotweed for 11 years.  I’m getting tired.


13 Responses to “Knotweed eradication, part eight”

  1. planthoarder Says:

    I hear you can eat its spring shoots for just a morsel of revenge.

  2. Lou Murray's Green World Says:

    I had to look up that plant, a new one to me. Holy cow, the roots go down three feet (or was that three meters?) it looks nearly impossible to get rid of. Its classified as one of the world’s 100 worst weeds. Glad it doesn’t grow out here in so Cal. Perhaps you need a small thermonuclear device. good luck.

  3. nruit Says:

    Good luck!

  4. Sherry MacKinnon Says:

    Hello! Unfortunately, the only real way to successfully deal with japanese knotweed is by chemical removal. We use Clearcast where I work to get rid of it and generally it takes two or three applications- once a year over t-3 years. Mowing, disking and cutting make it more vigorous and spread and makes the problem much worse. Root removal is very difficult because it is hard to get all the little rootlets and this is how the plant spreads. If the roots that you remove are not destroyed (fire or put into black plastic garbage bags and left in the sun to cook) they will reproduce in your compost or the landfill and spread from there…

    Drop me a note if you’d like more information! This plant has a great strategy for survival (which is the only thing really admirable about it).

    • Ali Says:

      Sherry, thanks for the info. We most definitely did not compost the debris. I will look into Clearcast as an option. I suspect our arrived on the property years ago as fill, judging by the junk we’ve pilled out of the area it is growing.

  5. Weez Says:

    A few years ago we had a young fellow come in with his machine to cut our lawn, BIG MISTATKE! Because the next summer we had a very nasty invasive creeping weed (that was hard to kill) that took over large areas of the lawn and spread throughout our lawn. We suspect that is was imported from cuttings off his machine from other properties. Beware when cutting the lawn area where the knotweed is that you don’t let the cuttings that attach to the bottom of the mower get into the rest of your lawn to propagate elsewhere.

    • Ali Says:

      Thanks for the tip, Weez. I know that is how we introduced plantain into our veggie garden years ago, on a rented tiller. This stuff is awful, it is widespread around here in the vernal ponds and streams. Ugh.

  6. El Says:

    Oh girl, you need some goats! Any nearby you can borrow? You might have to have them visit every spring, but…just think how much more landscape you’ll have.

    Since we’ve had ours, we can mostly see clear from one part of the property to another…to goat-on-their-hind-feet height. Kinda nice, and lots less multiflora rose, blackberries and…poison ivy!!

    That said, they do loves themselves some tree bark, so they have to be kept moving on or they’ll girdle your trunks. (Tree trunks, erp!)

    Now they’re working on our bamboo grass…

  7. Robin Says:

    I hate invasive stuff. I am impressed with your dedication of trying to get rid of it.

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