Knotweed in Carrigtwohill
There have been several reports of knotweed infestations in Carrigtwohill.
The Community Council is undertaking a survey to establish the extent of the problem with a view to instigating a treatment programme.
What is Knotweed?
Japanese knotweed (Fallopia japonica) was introduced into Europe during the mid-nineteenth century as an ornamental plant. It has since become one of the most problematic invasive weeds in Europe.
Japanese knotweed is a perennial weed, producing tall canes up to 3m in height during the summer. The canes have characteristic purple flecks, and produce branches from nodes along its length. The branches support shovel shaped leaves and clusters of white flowers in autumn. The canes die off in winter, turning brown and shedding their leaves. This produces a dense mulch that precludes the growth of native species
How Does Knotweed Spread?
Japanese knotweed canes grow from dense crowns that also produce extensive underground stems called rhizomes. These can produce new plants and research has shown that rhizomes can penetrate the ground up to 3m and spread 7m laterally. Roots are very destructive to tarmacadam, brickwork, drains and foundations.
Japanese knotweed is often spread from top soil imported on to site (fly tipping is reportedly a big issue in the UK), and from shard or slivers of stem created by trimming or flailing of knotweed in attempts to control it. A 5mm sliver of knotweed can generate a new plant.
Road verge flailing must be avoided as it can create linear infestations along the road.
How Can Knotweed be Controlled?
Eradicating knotweed is difficult, time consuming and expensive. The London Olympic site spent over £80M controlling knotweed in a scheme where tall rhizomes were excavated, sorted from the spoil and then buried and covered with a membrane!
Using a herbicide with appropriate controls is effective. Foliar (foliage) spraying requires several applications to be effective and can take 3 years of repeated spraying. A more effective treatment is stem injection – here one injects each cane like stem with a small amount of herbicide at the end of the summer.
Can I help?
We need to document all growths of knot weed in Carrigtwohill.:
• Look around your property for knotweed and report it to info@carrigtwohillcommunity.ie
• Do not cut, strim or flail knotweed – as it can rapidly spread.
• Do not remove soil from any knotweed infested site and be aware of the source of any imported top soil
• Only dispose of knotweed to a licensed site – this is a legislative requirement!
• Call your TD and County Councillors and make them aware of YOUR concern over this scourge
Knotweed effects us all
Please join with us to eradicate it from our community
