Invasives: Polygonum punctatum Dotted Smartweed

Discussion in 'Plants: Conservation' started by Treelover, Jul 25, 2008.

  1. Treelover

    Treelover Active Member

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    Hi to All,

    My yard has been invaded by what I believe to be Polygonum punctatum syn. Persicaria a/k/a Dotted Smartweed. I have tried killing them with horticultural vinegar but that only curled the leaves. Digging it out is horrendous due to the tangle of roots and I have neither the time nor the energy. I am not comfortable with using a propane torch. Any suggestions out there, short of Glysophate? I would really appreciate help on this one. Thank you.
    - Treelover
     
  2. joclyn

    joclyn Rising Contributor

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    i'd just use the glysophate and be done with it (after numerous treatments, that is).

    i usually just pull and/or dig up weeds - i prefer to not use chemicals. there ARE some that just require serious treatment - smartweed is one of them.

    to keep damage to the general area down to the bare minimum, i break the stalk and spray the weed killer directly into the center of the stalk. it works it's way down to the roots and the whole thing dies. i've not had damage to surrounding plants or even the grass when using the stuff like this.
     
  3. Treelover

    Treelover Active Member

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    Thanks, Joclyn,

    What a perfect reply and solution. I do agree on not using chemicals where they are not really necessary. I bought the glysophate and began cutting the tops off today because I saw they were about to produce their seed shoots. The liquid from the glyphosate bottle does not come out in a spray but more like a squirt, so you never can really get all sides of the leaves. The idea of spraying inside the stalk is ingenious. I'm glad that it does not damage surrounding plants, although I would be willing to sacrifice a few things to get rid of the smartweed. Thank you so much!

    PS: By the way, I had seen smartweed growing in a forest preserve many years ago and thought how lovely it was. Years later, it appeared in my yard for some reason. I guess it's true what they say - you have to be careful what you wish for because you might get it! In any event, I'll let you know how it goes. Again, thanks a lot.
    - Treelover
     
  4. joclyn

    joclyn Rising Contributor

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    good move on cutting the tops off to keep the flowers from going to seed...i do that, too. the neighbors think i'm nuts going around and pulling the dandelion flowers off...it works though! i keep missing the thistle though...that one goes from bloom to seed incredibly fast!

    the bottle i have doesn't quite 'spray' it, it's more like a small 'squirt', so it actually works very well to get it right in the top of the stalk...the spray doesn't spread out too far and that keeps it from going on things you don't want to do damage to.

    to make it go quicker, i'd cut the stalks down to only about 6 inches high...less plant for the chemical to travel through to get to the roots.
     
  5. Treelover

    Treelover Active Member

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    Thanks for the additional information. From what I have been reading, it says that for best results, do not apply product to plants that are drought-stressed. Now I am wondering if I should water them all first and then wait a day to spray. Did it make any difference in your experience?

    Also, I was wondering what you meant in your first post about having to do additional applications. Under what circumstances did you have to do additional applications - was it the same year, the next year, or did you mean you had to do it again because new plants sprouted up the next year? Thanks.
    - Treelover
     
  6. joclyn

    joclyn Rising Contributor

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    i learned by trial/error that it's best to cut the stalk down to about 6 inches and you get quicker results (as in: it dies quicker). i had this one thing growing and it was right in the flower bed (and next to the fence) and i didn't want to damage the good plants, so i topped it off and then applied the treatment...the stalk was over two feet and only the top portion died...new shoots started coming from lower on the stalk so i treated it a couple more times.

    it may have been a combination of not applying enough of the chemical (the stalk was pretty wide) as well as leaving the stump so tall. i really had no choice though, because of it's location - couldn't get to it from the front of the bed so i had to treat from behind the fence and couldn't make it too short or i'd not get to it. it took three treatments (or maybe just two, i can't remember now) over the course of about 6 weeks. that was a serious weed though!

    other things i treated were shorter and they only needed one treatment to be killed.

    i've made no notice about drought-stressed or not. although, maybe that was why the first treatment on the one weed didn't work...we had been in a very dry period at the time.

    the only other thing i treated more than once was the thistle...the first time i just sprayed it on...didn't break the stem to get the poison right into the plant. the second time i did do that and it was kaput in a few days.
     
  7. Treelover

    Treelover Active Member

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    I will be sure to cut them down to at least six inches in height. My plant stalks are quite narrow - maybe 1/8" to 1/4" so I hope the chemical goes own to the roots.

    It's really too bad they don't have anything that you can apply strictly to the roots. It would make it so much easier but then, I guess, you would be contaminating the soil too much with a flood of chemicals.

    There is another alternative I might try if what we propose does not work. I am going to do solarization. You get clear, thin plastic sheeting and cover the whole ara and hold down the edges with bricks or weights. Then you just let them bake in the plastic for 2 to 3 weeks in hot sunlight. I know they do this technique to kill seeds and diseases that may be in the soil but they usually remove the plants first. It certainly is worth a try if I cut them short and then cover them with plastic.

    Thanks for all your help on this, Joclyn. I'll let you know how it all turned out. Good luck with your yard problems. I hope your garden is thriving and that you are having a wonderful summer.
    - Treelover
     

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