Japanese Knotweed (Fallopia japonica) was introduced to Ireland as an ornamental plant in large country gardens and estates. It is now widely considered to be one of the world’s worst invasive species. In temperate climates it frequently colonizes roadsides, waterways, and waste areas. One reason for the rampant spread of the species is the plant’s tolerance of a wide range of soil types and pH levels. Colonies of the plant are quite dense and completely crowd out other plant species. Plant rhizomes can extend beyond 10 metres across and 3 metres down in the ground. This makes removal by excavation extremely difficult and often ineffective. The species can survive temperatures down to -30 degrees celsius. It is unaffected by cutting, as it re-sprouts from the rhizome during the growing season. The plant dies back in the autumn period exposing underlying soil to the elements. The most effective method of control is by herbicide application but product selection and timing of application is crucial to achieve desired results.
Japanese knotweed is listed as an invasive weed in the Control of Aquatic Invasive Species and the Restoration of Natural Communities in Ireland (CAISIE) – European Commission Life+ Programme.
If you have a problem with invasive weeds in your local authority area, on club grounds or a private property that you manage, call us for professional assistance and service.