No, Japanese knotweed cannot be completely eradicated; even attempts using fire or acid have proven unsuccessful due to its resilience and ability to grow from small rhizome pieces. The only way to completely get rid of knotweed is to excavate all parts of the above and below ground plant and remove it from site to a licensed landfill site.
WHy can’t knotweed be eradicated?
Knotweed is a highly resilient plant species, it can survive extreme climates from volcanic heat to sub-zero temperatures. Any attempts to ‘kill’ the plant with bleach, fire or mowing will not be effective. If a tiny fragment of rhizome is left in the ground it will grow new plants. Rhizomes have been known to remain viable (and regrow new plants) after 20 years or more of dormancy. This usually happens when the rhizome has been disturbed through construction or building works.
what about chemical treatments?
Chemicals (herbicides) are applied either by spraying over the plant, wiping it onto the leaves or injecting it into the stem (as shown above). With a series of planned treatments (at the right time of year) and over time, the herbicide translocates down to the rhizome putting the plant into a dormant state. This does not however ‘kill’ the plant, it can revive and grow back if the ground is disturbed. This is why we only recommend a treatment plan when there is no risk of further development or building on the infected land.
To find out more about our knotweed excavation solutions speak to the team.