You’ve probably heard horror stories about it, but what is it, why is it such a problem, and what can you do about it? Wildscapes CIC’s Conservation Contracts Manager Steven Greenwood explains all.
What is Japanese knotweed?
Japanese knotweed (Fallopia Japonica) is an herbaceous perennial, native to Japan, where it is thought to have evolved as a first-coloniser of post-volcanic soils. In its native environment it is heavily eaten by insects, losing approximately 40% of it leaf cover each year.
To combat this predation, it has exceptionally fast vertical growth, capable of growing up to 10cm each day. It is also excellent at fixing nitrogen in the soil (better than any other plant in the UK). In Japan, this accumulation of nitrogen allows other species to establish and out-compete the plant, causing it to go dormant after about 50 years. In the UK it is a different story altogether. Introduced in 1850 and valued as an ornamental plant in large gardens, its highly vigorous nature soon became apparent. With no predators to eat its leaves, by 1886 it became established on brownfield sites in Wales. By 1905 it was advised against keeping the plant in the garden unless kept in check. A hundred years later and it has become established throughout the UK, colonising riverbanks, railway lines, motorway verges and vacant plots.
Why is it a problem?
Wherever the plant becomes established it will impact upon the local environment. Its thickly matted stems, reaching 2-3m, reducing biodiversity by outcompeting all native plants, its extending rhizomes exploiting weaknesses in built structures, causing lenders to withhold mortgages from properties infested by the plant, and its presence on development land causing costly delays to homebuilders.
Under the Wildlife and Countryside Act 1981 you would be breaking the law if you allowed Japanese knotweed on your property to spread into the wild. This would include allowing the plant’s rhizomes (which can extend 7m underground) to spread from your property into neighbouring land.
Once dug up or cut down, any waste containing Japanese knotweed becomes controlled waste and is subject to legislation under the Environmental Protection Act 1990. This legislation places a duty of care for its handling and disposal and this waste must be taken to a licensed landfill site by registered waste carrier.
Wildscapes have specially trained surveyors and technicians that provide cost effective solutions to Japanese knotweed. Our methods comply with the latest legislation and industry standard codes of practice. If you have a problem with Japanese knotweed please contact us for a no-obligation free initial assessment.