The Exchange

One important feature offered on the Got Weeds? website is this information exchange which allows viewers to search for invasive plant scenarios similar to their own.  There is an abundance of good work being done throughout Vermont, New Hampshire, and neighboring states; my goal is to highlight success stories where manual control methods triumphed.  Even if the efforts are not yet fully successful, there is still value in studying the work to pick up critical lessons.

Success stories and lessons learned are highlighted on the Case Studies page; all of them run through at least the 2013 growing season.  I had hoped to capture data on control costs and some guiding principles, but I have found that most sites are very complex with multiple problematic invasives.  So it is really difficult to present a clear cost program; often there is serious preparation work simply to “safe the site” for ongoing control.  How do I quantify that?  No one wants to work under overhanging dead limbs or in a tangle of barbed wire, but those costs are kind of indirect.  Important yes, but still somewhat tangential.  And sites are often plagued by depleted, compacted soils.  Again, some effort should go toward site rehabilitation, but what portion of that truly ties in to the eradication of the target species?  Hard to pin down.

So I believe the case studies page is the most useful way to present Lessons Learned and some of the management nuances.  Every site is unique and presents some kind of unusual feature, but the case studies are good background knowledge.  I am happy to respond to inquiries for further detail and would enjoy seeing photos that clarify any key issues.

Please keep in mind that control efforts are absolutely long-term in nature.  A species is not considered “eradicated” until a site has been monitored for three years with no recurrences of the target plant; this is regardless of whether it was chemically, manually, or mechanically treated.  I consider the transition of a site to be the mark of success; when an array of native species have replaced the invasives, good things will continue to happen.

Please email me if you would like to submit details on a manual / mechanical control project that you have conducted.  I will ask you for a significant level of detail, so be prepared for that, or upgrade your record-keeping as you embark on your control work!  Spreadsheets are fairly simple in that regard – I can send you a template.  Thanks for your interest!

Current projects include:

  • Black swallow-wort (vine) in Royalton and Randolph
  • Autumn olive in Pomfret (cutting and flaming)
  • Japanese knotweed in Randolph, Royalton, and Pomfret
  • Giant hogweed (dangerous!) in Woodstock, S. Woodstock, E. Montpelier
  • Wild parsnip (dangerous!) in Brownsville, Norwich, and Pomfret
  • Wild chervil in Royalton and Chelsea (cutting, pulling, smothering)
  • Multi-flora rose in Randolph, VT, and Enfield, NH (cutting / pulling)
  • Garlic mustard and Japanese barberry in Pomfret
  • Garlic mustard in Lebanon, NH
  • Japanese and European barberry in Thetford (flame treatment)
  • Honeysuckle in Thetford, over 1700 plants pulled / flamed
  • Honeysuckle and Japanese barberry on two locations in Stowe (2997 barberry pulled in 2015)
  • Oriental bittersweet (vine) in Royalton, VT, and Sterling, MA
  • Multiple species on a multi-landowner site in Norwich (the buckthorns, 4 other shrub species, wild parsnip)
  • Solarizing (look this up online, very interesting, many variables to manage, but quite successful on wild parsnip)
  • Yellow-flag iris in both ponds and stream channels (Sharon, Pomfret, Lyme NH)
  • Meadow rehabilitation in Durham, NH, multiple shrub invasives and wild parsnip

10 Responses to The Exchange

  1. Shelley says:

    How realistic is it to try and fight a large area of japanese knotweed on a steep streambank? When we bought our house 20 years ago the knotweed was trying to crawl into the foundation – we beat it back but despite what I can only call herculean efforts in the past including years of digging up rhizomes and even glycophosphate we now have one of the healthiest looking batches I have ever seen. We are out of energy at this point and have reached the conclusion that we should just leave it alone. Thoughts?

  2. treeguyvt says:

    Well Shelley, several thoughts…. I certainly admire your commitment and tenacity and can only say that your example demonstrates how tough this plant is. Remembering that only one quarter of the plant is above ground, when you say a large patch of Japanese knotweed, just know that you are dealing with a lot of stored energy.
    So: first, I’ll just remind folks that if you are resorting to chemicals, please use them absolutely according to the label. And the expression “close to or near water” means that you need to be very conservative in where you apply these things. At least in Vermont, herbicides approved for use in or near water are restricted to professionals, so there is nothing you can buy that should be applied to stream banks. But every site is unique as far as how far back from the water you should go, so again please take the cautious approach. And my point here is to remind all of us, not just Shelley, to be careful with the chemicals, both the handling of them and the application.
    Moving on, pretty much all invasives growing in full sun are much more difficult to eradicate. Bring in shade if you can, but I know it’s not possible to plant trees in the middle of the road or the brook. Thus, a site oriented to the south may be near impossible to manage.
    And I wonder, Shelley, if you were cutting or otherwise controlling the entire patch of knotweed at your site or just part of it? With rhizomes that can go up to 60 feet underground, it’s no wonder that cutting only part of the patch does not impact the plant over the long term. My experience says that you need to cut the entire patch, cut it around ten times per growing season, and try to control it while it’s still less than the size of a car. Beyond that size, the effort becomes huge.
    Back to the chemicals for a second…. Japanese knotweed is a plant that sends a lot of energy to the roots after it flowers, so timing is crucial with chemical applications. I cannot give advice on the actual application of chemical controls (because I’ve chosen not to pursue a commercial applicator’s license) but a professional applicator or your state agricultural folks should be able to help you with the question of timing.
    Lastly, on whether to continue the struggle…. Look around your property and see if you can identify any other invasives that might try to occupy the ground currently held by the knotweed. If you have goutweed (bishop’s weed) for example, I think I might just let that knotweed stay put. Goutweed seems to take over sites that I’ve seen at an amazing rate, again every site is unique, but it is equally as difficult as knotweed to contain or eliminate. So don’t open the door to another plant coming in behind the one you’re trying to remove! This all feeds into your vision for the property, which should guide your efforts.
    So Shelley, I hope these thoughts are helpful. I usually tell folks that the first year with Japanese knotweed is the hardest, due to sheer volume of material, but I’m not going to say that to you in year twenty! Whatever you do, just don’t let any little plant fragments fall into the brook; your downstream neighbors will appreciate that. Good luck, and let me know if you choose to lower the shoulder and go the intensive cutting route. I know steep banks are not particularly fun worksites…. be careful, and thanks for writing!

  3. Shelley says:

    Hi – thank you for that thoughful response. The knotweed was here long before we were; in fact, it was here before I was born according to my neighbor and was likely planted deliberately with the good intention of stabilizing the steep bank – a task which it has accomplished admirably. And, it IS quite beautiful but looking down on half an acre of an invasive plant just gnaws at me. We have had NRCS visit the site (and the Soil Conservation Service before that) and they both recommended using a three pronged approach which included Round Up, digging up rhizomes and repeated mowing. We also burned everything we cut. Of course the bank is way too steep to mow and too much messing around on it will no doubt result in erosion so we have to be very careful. Plus if we kill off the knotweed we still have to have something to keep the bank stable. Whiel I woudl love to see it go away, I think the goal should be to contain it where it is needed but it seems to be spreading. The bright side of our early efforts was that we cleaned the bank of many sacks fulls of metal and bropken glass that had been thrown there for the last 100 years or so.

    The knotweed does not go all the way down to the edge of the water – has about a 30 – 40 ft buffer right now and doesn’t seem to be moving in that direction. There is a type of sawgrass (really coarse) between the knotweed and the brook that for some reason keeps the knotweed back.

    My understanding is that for very large stands of knotweed, current experiments include injecting the glycophosphate directly into the rhizomes. I am chemical phobic so we don’t apply anything ourselves. We are actually in NH BTW.

    When we were trying to deal with it way back we cut the entire patch to the ground (we were much younger then) repeatedly in the same season as you suggested and we had an applicator apply the round up while the plants were flowering which is, I am told, the correct time. We also covered sections with black tarps. The effort was definitely was keeping it under control but as soon as we stopped that intensive effort it came back. We did have one area closest to the top of the bank where we seemed to have eradicated it and we planted conservation mix and it did take it a few years to get through that. We have tried putting goats on the bank and they would eat the small shoots but they got sick from eating it.

    Still, it was contained in one area at least but a couple of years ago we had to remove a huge thorn apple that had been hit by lightening and split down the middle from an area adjacent the knotweed – of course the knotweed moved right in so has now spread to another area.

    The only natural plants that seem to keep it in check is the sawgrass below and the Sumac up top which seems just tall enough to create a canopy that blocks the light and on one side we have tall pines that also seem to block light. We have a number maples on the bank the top and around the sides of the bank but they are tall enough that there is still plenty of light and the knotweed grows right underneath them and flourishes.

    I am not sure I have the energy to start the battle again but I notice that it seems to be pushing towards the house again so I may have to!

    • treeguyvt says:

      Thanks for the details Shelley…. taking on a half acre of established knotweed IS a huge project. No wonder it’s held on through all the treatments. I think you got reliable advice from the specialists whom you’ve worked with in the past, but I could make one or two points. First, I’m not surprised that the sumac kept the knotweed in check…. it is supposed to chemically suppress other plants under its immediate canopy, so apparently it was doing just that at your site. And yes, the latest chemical treatment method for knotweed is the stem injection technique, which has the positive effect of wasting hardly any herbicide. It all goes into the plant and translocates down to the roots.
      But I’ll have to ask you for a photo of the sawgrass that you mention keeping the knotweed in check. That’s no small accomplishment, so whenever you get a moment, please send a photo…. be sure to capture the details of the leaf and any seed heads…. thanks in advance, I”m really intrigued by the possibility that this grass is holding its ground. I’m sure the knotweed would love to move into that space closest to the brook, so again it’s amazing that the sawgrass has held on.
      Lastly, if you do want to renew the control efforts, I can save you some work by telling you not to worry about piling and burning the cuttings. Just let them lie where they fall, as long as there’s no danger of them being washed into the brook before they dry out. Cut as close to the ground as possible so you don’t gash your leg later on a dried and hardened stem – a real possibility. And if you can get some other plants established, like ferns, speckled alder, or willow shrubs, they could help intercept the sunlight. I was told a long time ago to forget smothering as an option, but if you can cut carefully without destroying any natives that are present, those native plants, as they re-establish, will do some of the smothering for you. Not enough to eliminate knotweed, but they’ll be adding to your overall effort.
      Good luck again, and watch out for other invasives trying to sneak in while you are so focused on the knotweed! Mike

  4. Shelley says:

    Thanks Mike – I will take a hike down the bank this weekend if it stops raining and get you a picture of that grass!

    Shelley

  5. treeguyvt says:

    Hello All,
    Hope you weathered Irene OK. I thought it might be helpful to fill you in on an opportunity. A lot of my invasive control work is in streamside areas, and many of these suffered some serious re-arrangement or white-washing during the flood event of 28 August. With the ground cover stripped away in a lot of places, we have a moment here to look over the landscape and spy those invasive plants that are sneaking into an area or that got swept in. I’m thinking here of goutweed; single plants or small clumps have popped up in an area where I am tackling Japanese knotweed. There are large populations upstream, but the flood has given me the opportunity to nail these colonizers before they can establish and take advantage of the temporary full sun conditions. I am at a key moment with this project; the knotweed has been removed in this initial season, but the natives have not yet had a chance to rebound.

    So I encourage you to have a look at your property and seek out any plants that look like they may have washed downstream to you. I even found some Japanese knotweed hanging in trees, so the potential for downstream spread is real. Send photos if I can be of help.

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  7. Jonathan says:

    Shelly wrote:”My understanding is that for very large stands of knotweed, current experiments include injecting the glycophosphate directly into the rhizomes. I am chemical phobic so we don’t apply anything ourselves. We are actually in NH BTW.”

    I have knotweed in four locations. The only thing that has worked is the application of glycophosphate injected into the rhizome. I have never used herbicides or pesticides on my property. I only use organic fertilizer. It was with much trepidation that I resorted to the chemicals. Working with the Norwich Conservation Commission which purchased an injection gun and the glyco, we injected a small infestation of knotweed as a test. It’s very tricky work, crawling around on your hands and knees, wearing full protection, trying to inject stems and marking them so you know which stems have been marked. The results were dramatic. If you don’t include the stems we apparently missed, the glyco does the job! I can’t imagine injecting every single stem on my property but it seems to be an effective option. It would be nice if the state helped out on the purchase of the injection gun and the cost of glyco.
    MIke–a question for you. How do you dispose of the rhizomes that you dig up?

    • treeguyvt says:

      Jonathan,
      I tend not to dig up the rhizomes, unless I am working in an area that is already disturbed or transitional, such as a gravel bar. I go with repeat cutting, and I push for up to ten cuts in a season. The more you do up front, the more you stress the root system. With our lengthening growing season, three cuts annually is not enough, four or five effectively contains the patch, but aggressive cutting up to ten times gets the site under control in two years. Then you have a chance to finish it off easily over another several years. Plan on anywhere from five to seven years when cutting.
      With cut stems, I just lay the plant material out in the sun above the hi-water channel. The sun cooks it all down over the course of a month or so. If you keep at it, you never have to deal with a huge quantity of material again…. you’re cutting it at about one foot in height. And you’re allowing native veg to take over, but watch out for other invasives coming in the back door (goutweed).
      If I do extract roots, I often set up a couple pallets as a “weed drying station.” Again the sun cooks them right down. They may re-sprout, but no matter, they are up off the ground. So the pallets can be a little work to set up, but they’re free and they minimize the effort associated with cut / pulled plants….burning is not necessary, hauling to the dump is not necessary. I don’t like to create work for people- the only golden rule is not to allow any root or stem fragments to float or disperse downstream.
      Be aware, that since all the knotweed is connected underground, if you do not cut or treat the ENTIRE patch at once, I think you’ll see limited results and serious growback if you break off the work, regardless of treatment method. And the worst mistake is to cut it once or twice a season, to get the knotweed theoretically “under control”. The plant simply goes horizontal…. you’ve denied it the chance to go upward, so it goes sideways, and the patch ends up being HUGE in just a couple years, once the landowner completely abandons the effort. I’ve seen this, sadly.
      Thanks for the question,
      Mike

  8. Jonathan says:

    Yes, I’ve tried cutting but I can’t keep up.
    That’s why I tested the stem injection.

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