Control Knotweed by Excavating or Digging the Crowns
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- Опубликовано: 2 окт 2024
- This video describes how to dig or excavate knotweed crowns. Excavating knotweed is especially useful after one year of treatments with herbicide. After a year of treatment, the number of stems will be far fewer, the stems will be shorter, and the rhizomes smaller.
00:15 Video does not cover using heavy, motorized equipment for excavation.
00:36 Target of digging operation is the crown
01:03 Recommended tool is a cutting spade
01:45 Two situations where you shouldn't dig - utilities and waterways
02:00 Calling 811 before you dig
02:17 Digging near waterways can lead to stream pollution from topsoil
02:54 Three situations where digging makes senses
03:17 First situation - a year after a successful herbicide treatment
05:02 Second situation - before a a treatment but where some knotweed is location in bad places like near a structure
05:22 Third situation - where you don't want to use herbicides at all.
05:58 Two approaches after a successful herbicide treatment
06:34 Disposal of knotweed stems and dug crowns
07:00 Disposal of stems
07:37 Disposal of excavated crowns
08:36 If possible keep all knotweed parts on site. If that's not possible, check local and state regulations regarding disposal of invasive plant parts.
Thank you!
Very informative as usual. I am in the 1st year after treating my large knotweed patch with glyphosate last fall. I have probably killed 90% of it. Digging up old crowns shows that they are already starting to rot. I still have some stragglers in the main field and some shoots coming up further away, which I regularly dig up and dispose of in plastic bags. However, sometimes I wonder if this could make things worse: I have read that digging and disturbing/cutting the rhizome can cause the plant to continue to grow laterally underground. According to this view, you're supposed to leave it completely alone until autumn to do another herbicide treatment. This is all a bit confusing but I have definitely made a lot of progress, I really liked your 9 mistakes about knotweed treatment video!
This is the key question. Unfortunately, there is very little research on the best methods of knotweed control after the first year of successful treatments. My working theory is this: After you have killed the bulk of the knotweed clone with herbicide treatments, the rhizome network consists of small diameter rhizomes that connect dispersed stems. Those stems are also less robust. I have found that if you just retreat only in the fall, you can kill that crown and a couple feet of rhizome around the crown, but another plant pops up the next year that's three feet away. It seems like you reach an equilibrium. As I see it, the one advantage of regular digging is that you can both deplete the stored carbohydrates and deprive the clone of new carbohydrates throughout the growing year. In any event, I don't see how digging (again only after a good treatment) could make matters worse - the rhizome can only have so much stored energy.
@@GreenShoots Sounds reasonable. I'll just keep digging then. Is your experience that by doing so you can get past the equilibrium described above? So is there a stage after a few years where you won't find any knotweed shoots in early summer? Or is identifying knotweed a skill you need to pass on to future generations if you had an infestation at some point?
@@SuperFeist I am past that equilibrium at some of the sites i work on, and I visit them at most 2-3 times a year to check. Totally eliminating knotweed it tough. The plant is so tenacious even when it is just barely hanging on. If you are dealing with a more residential site, it might be possible because you can spot the growth more easily.
When yanking individual stems I find interesting that some snap off at just under the surface, others come out with a 6" below ground stem attached, a nice white then pink piece and others come out with a foot long horizontal rooty (rhizome?) piece. A real lottery toss up.
In the local stand I mess with I find that in the springtime at least it is not a monoculture. It shares the space with the early riser, garlic mustard. So when I take out the garlic, I opportunistically take out kw shoots or small crowns. Large crowns are abused by pushing the stems down flat.
@@williaml8474 I find that same inconsistency in how easily the crowns and rhizomes come up. In early spring they seem to come up easier. Maybe as the plant grows during the summer it creates more roots to brace the stems which are quite heavy by summer. Also, that's a good observation about springtime that I hadn't thought about - knotweed does seem to need time before it really starts growing. It makes sense that other plants take advantage of this opportunity.
Hi sir! Thank you for your amazing video. This was the most well done and most informative I’ve come across about excavation of knotweed. I am finally going to tackle our knotweed infestation and it is late spring going into summer. I have not done any treatment and I have an area of knotweeds surrounded by vine thorns and all kind of plants. Due to the surrounding plants/spiky vines, the use of weed wacker is necessary to get to the knotweeds. Once I clear the area and am able to get the the stem. I will treat it with herbicide and wait for next year and excavate every knotweed. Is this the way to go?
You are welcome! Thank you for the support! If I understand your situation correctly, here's what I would do: Plan to treat this fall. Use your brush cutter to cut access paths to the knotweed. Try to figure out which plants near the knotweed you would like to keep. Protect them. If there are other invasive plants mixed in with the knotweed, treat them together with a foliar application in the fall. I would do two applications. Then, the following year excavate the shoots per the video. Does that make sense?
@@GreenShoots yes sir! Thank you, I will do just that. 👍
In the winter, I started beaking off stems of really tall ones. Maybe 15 feet? I'm not allowed to use any chemicals there. There are some new ones growing from the same bases, but also some little new ones that I've started digging up. They are all growing up through our Forsythia, and I don't want them to do this again 😢.
If you can't use herbicides, I would definitely dig the ones you can dig. If a knotweed clump is too close to one of your forsythia to dig, repeated trim it back. Also, try to knock off the dormant buds.
One of the most useful descriptions of a doable plan for removing this nasty weed. Thank you!
Thank you for your support!