EU (Birds and Natural Habitats) Regulations 2011 make it an offence to plant, disperse, allow dispersal or cause the spread of listed species such as Japanese Knotweed (Fallopia japonica).
A list of Invasive Species in Ireland can be found on www.invasivespeciesireland.com. Sightings of invasive species can also be reported on this website or on the website http://records.biodiversityireland.ie/record/invasives.
Japanese Knotweed (F. japonica) is native to Japan, Korea, Taiwan and China, is now widespread in continental Europe and Britain. Knotweed is suited to a wide range of conditions, including full shade, high temperatures, high salinity and drought. It is found near water sources, such as along river banks, low-lying and disturbed areas. It can colonise coastal shores and islands.
Japanese Knotweed is a threat in open and riparian areas where it speads rapidly to form dense stands, excluding native vegetation and prohibiting regeneration. This reduces species diversity and alters habitat for wildlife. Once stands become established, they are extremely persistent and difficult to remove.
If you find Japanese Knotweed on your property, prevent any further spread of the species. Do not strim, cut, flail or chip the plants as tiny fragments can regenerate new plants. It is also advised not to dig, move or dump soil which may contain plant material as this could contribute to its spread.
Japanese Knotweed can be controlled successfully through the application of appropriate herbicides by a competent person. The eradication of this plant requires planning, as follow up treatments are usually required, and consideration should be given to the management and disposal of dead plant material and to the treatment of contaminated soil.
Some types of Dogwood, Lilac and Flowering Houttunyia are sometimes mistaken for Japanese Knotweed. Note that Knotweed stems are not at all woody, so anything with bark that can be stripped or twigs that snap to show a solid, woody core is unlikely to be Knotweed.
For information on Japanese Knotweed, see:
- Identification Guide for Japanese Knotweed (Biodiversity Ireland)
- Identification Guide for Japanese Knotweed (Invasive Species Ireland)
- Plants that can be mistaken for Japanese Knotweed (Invasive Species Ireland)
- Management of Invasive Species (Invasive Species Ireland)
For a list of Invasive species, see www.invasivespeciesireland.com