Eliminate or contain invasive plants

Discussion in 'Garden Pest Management and Identification' started by Olafhenny, Jan 28, 2009.

  1. Olafhenny

    Olafhenny Active Member 10 Years

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    Okay, here is my list of most despised invasive plants, most obnoxious first:

    1) Violets. Like mints they spread through rhizomes (underground runners) and like a moist environment. Unlike mints the also spread profusely through seeds. But what makes particularly vicious spreaders is, that a portion of their seeds lie dormant for up to three years. So even if you let never another violet come to flower, they keep on springing up for three years. You have to pull them out, before they form that little knob at the base of the leaves, because immediately thereafter they start sending out rhizomes and you have to dig.

    2) Mints. If you leave even a 1” section of the rhizomes in the ground, you will soon have another mint plant proudly surviving and spreading. If you leave a section smaller than 1 “ you will probably soon have… . During my childhood we lived near a small swampy area, which was teeming with mint, so much so, that you could harvest it with a scythe in places with only little contamination by other plants. So here are your choices as far as I can see them:
    • Dig up the infested area, sift thoroughly through the soil and remove by hand every little bit of rhizome you can find. Thereafter watch the area closely for any new plants piping up and remove every part of them. That is how I got rid of mine.
    • Easier would probably be, to spray the whole infested area with a weed killer and start anew. You could probably remove any plants you want to preserve prior to spraying.
    • This is a long shot, but you could try to deprive them of water.

    3) Snapdragon. They are proliferate seeders and some of their seeds can also lie dormant for 3 or 4 years.

    4) Ajuga. This shade lover can easily be contained with a 6” deep in-ground plastic barrier

    5) Trifolium repens dark dancer, a dark four leaved clover ground cover. Spreads very rapidly by expansion of plant mass. Mine is contained between house, concrete sidewalk and concrete base of the outdoor heating & air conditioning unit. But I believe a six inch deep plastic edging would probably contain it.

    6) Alyssium seed out in abandon, I got rid of them in our yard, but the neighbour had them at the property line and the seeds kept spreading over. An about 4’ wide barrier of dense ground cover blocked the ‘invasion’ out successfully.
    Most of the above plants I won’t even let on my compost.

    7) Larger plants. For the other, larger plants like asters and bamboo I dig a hole in which I insert a plastic tub with the bottom cut out, top rim flush with the ground and plant them in there. That way the roots can expand below, but the rhizomes are contained.

    Oh yes, and there is horsetail. The same neighbour who was giving me alyssium (and dandelions*) in the front yard has a regular horsetail farm growing along the shore of a pond, which we both share. I got rid of mine, but they keep on invading underneath the fence. Because these pests have very little greens on them, they do not easily succumb to weed killers. It takes at least 5 or 6 applications of RoundUp in short intervals or to use the concentrate at $50.-/litre. The problem is, as much as you try to limit your spray, it takes so little of it, to kill everything around it too.

    Fortunately this man has now put his house up for sale and one other neighbour, who is interested in buying it has already asked me how to get rid of the horsetail, but he is now down south for the winter. :(

    * Dandelions do not bother me much, because they cannot penetrate the dense ground covers in our front yard.
     
    Last edited: Jan 29, 2009
  2. Ron B

    Ron B Paragon of Plants 10 Years

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    Sounds like you might be talking about scouring rush. That is leafless.

    Glyphosate is to be used with extra caution near water.
     
  3. growing4it

    growing4it Active Member 10 Years

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    According to a botanist that I knew who hated violets too, violets will continue to grow even if "you rip their heads off". They are tenacious. According to name dictionaries, my name means 'violet'. I kinda like that.
     
  4. Olafhenny

    Olafhenny Active Member 10 Years

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    No, Ron, I am actually talking about the kind of horsetail as pictured here:

    http://www.florahealth.com/flora/home/Canada/HealthInformation/Encyclopedias/Horsetail.htm

    It is of course closely related to scouring rush and looks in its early stages just like it. The tendril like "leaves" develop as the plant matures. But even with the tendrils developed, there is little for weedkillers to attach to. These horsetail seem to form mattes consisting of separate plant units. When I kill horsetail on my side of the fence, a few also die on the other side, sometimes back a few feet, while others nearer to the fence survive.
     
  5. Michael F

    Michael F Paragon of Plants Forums Moderator 10 Years

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    For info, the one in the photo at that link is Equisetum telmateia, not the E. arvense described lower down the page. E. arvense can be an awful weed; E. telmateia is usually not (it is fairly restricted in habitat, liking swampy ground).
     
  6. nic

    nic Active Member 10 Years

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    Well, it just goes to show how different we all are. Apart from the horsetail(nothing to recommend it except history), and the bamboo(rustles in the night and sounds like burglars when you're alone in the house) I love all of these, and all are welcome. I wish Snapdragons would selfseed for me, my alyssum was pulled out by blackbirds, the violets came from my mother's garden,and Ajuga grows where little else will in the black shade by my northfacing back door.
    But! Geranium phaem, (why is the seed so expensive?Because it escapes before you can harvest it) G.endressi, any willowherb(from the neighbours) Sycamore seedlings, which pop up at six inches high(wasn't there yesterday, now can't pull it out), and a furry Inula which I like a lot, just not everywhere. And Foxgloves. Mint is a problem, but I can just about keep it where I want it, but raspberry canes emerging in the middle of the strawberries is a bore, because I will want them to be moved to replenish the row, not make a new one...
    As for alpine strawberries in full sun outside the front door, absolute thugs. And there's a creeping Campanula that charmed me by scrambling through low shrubs, until I saw it smothering things like houseleeks.
    To each their own.
     
  7. Chungii V

    Chungii V Active Member

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    Glyphosate is used a lot to control water weeds etc. It is actually reasonably safe for aquatic life. The active constituent will adhere itself to dirt particles in the water. One thing that has always been stressed to me is the importance of clean water when using glyphosate for that reason. Dirty dam water will highly reduce the effectiveness of glyphosate. The councils use it to control some water weeds in our area.
    I believe that this is why it has a small residual effect for a short period of time, even more so with repeated sprayings.
     
  8. ckirsch

    ckirsch Member

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    Olafhenny

    Am I an idiot? I bought "horsetail" last year at Lowes. It grew nicely and filled in the spot that I wanted. It planted it in a fairly contained area and it has not spread (only one season). My wife does not like it where I planted it, so I replanted it an an area not as easily contained. NOW I read that it is the "devil's weed" and I am concerned about it over taking my lawn and other flower beds. Should I be concerned?

    BTW, the picture that you posted does not look like the "horsetail" that I planted. Mine has no sprouts off of the sides. Is this a less invasive Lowes version or is it just too young to start sprouting off of the sides?

    I just replanted (today) Is my best bet to rip it up and throw it away?

    Please help you seem very knowledgeable.

    Ckirsch
     
  9. Landscaper

    Landscaper Member

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    I think a lot of these plants could be defined as “boo boo” plants, meaning that people make the boo boo of planting them. While I have, or have had, all of the above plants, none of them have actually become pests. Blame that on the harsh environment. Nevertheless, some mint I will only containerize, as well as the scouring rush – which adorns my koi pond.

    My neighbor, who I guess is a bit naïve, has a habit of planting things that she doesn’t know anything about. If it looks interesting or pretty she’ll plant it. A few years back I caught her planting wild buckwheat, which she picked up from a friend. Some friend, eh? She called it “snake vine”, however still a weed by any other name in my book. And yes, in time she ended up spending a lot of hours trying to remove all of the weeds, but they still come back every year. Did she learn? Last year she planted a pretty yellow flowing plant that she picked up from the other side of the mountains… scotch broom. Oye vey!

    By the way… while indeed Glyphosate is reasonably safe, the manufacturers label for Roundup (Glyphosate) states “Do not apply directly to water, to areas where surface water is present or to intertidal areas below the mean high water mark.”
     
  10. kaspian

    kaspian Active Member 10 Years

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    Ha! I was just thinking exactly the same thing. I love most of these plants, especially bamboo. (Okay, I'm not wild about alyssum or snapdragon.)

    Of course, I live in Maine, where none of this stuff grows vigorously enough to become a problem.
     

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