Over the past 18 months, over €186,000 has been allocated to projects run by local authorities around the country to tackle Japanese Knotweed.
According to the Department of Housing, Planning and Local Government, the invasive species is now “firmly established” across Ireland.
The plant has been recorded over 4,500 times over the past decade.
Japanese Knotweed, or Fallopia japonica, was first brought to Europe from Japan as an highly prized ornamental plant in the 19th century and was then introduced into the wild in Ireland in the early 1900s.
It was sold in garden centres up until the 1980s and spread to its current level through people planting and discarding it.
So why does Japanese Knotweed pose a threat?
From a biodiversity perspective, the species, which can reach up to 3m, is capable of spreading rapidly in open areas, forming very dense strands at the expense of native vegetation.
The plant can also pose a significant problem in urban areas as it can grow through tarmac and cement, but only if a weakness already exists.
Infestations can also impact on houses valuations.
Although there is no national eradication plan in place for the plant, there is a legislative framework around invasive alien species, including Japanese Knotweed.
“Much of the work in tackling Japanese Knotweed happens at local level and is carried out by local authorities in their areas through their own biodiversity action plans,” a department of housing spokesperson told Agriland.
A National Invasive Alien Species Management Plan is included in the Programme for Government, but is currently at the early stages of development.
The Local Authority Biodiversity Action Fund, which is administered by the National Parks and Wildlife Service (NPWS), supports approved projects targeting invasive species.
“In 2021, €515,049 was awarded to local authorities to deal with invasive alien species, €116,926 of which was used in projects relating to Japanese Knotweed.
“A further €69,104 has been awarded to Japanese Knotweed projects so far in 2022,” a department spokesperson added.
I have Japanese Knotweed on my land – what now?
By law, control of invasive species such as Japanese Knotweed is a matter for landowners.
Firstly, it is important to confirm whether the plant is an invasive species or a common native plant that does not need to be treated.
This can be done by contacting a local expert or by submitting images to Invasive Species Ireland for help with identification.
It is also crucial to note that you should not cut, dig up or dispose of the plant without first seeking expert advice as you are risking its spread.
The plant can prove difficult to eradicate as even after specific herbicide treatment the roots can remain viable for up to twenty years.
Landowners are encouraged to develop a management plan that is specific to the site and, if necessary, speak with adjacent landowners about the plan.
A licence is required to remove and dispose of Japanese Knotweed under the European Communities (Birds and Natural Habitats) Regulations 2011 and all contractors employed to carry out this work should be licensed to do so.