Japanese knotweed hotspots revealed
PARTS of Wales – including Swansea and Llanelli – have been identified as being particular UK hotspots for the notorious invasive garden species Japanese knotweed.
Environet has released a heatmap from Exposed(tm): The Japanese Knotweed Heatmap, revealing areas in the UK considered at high risk for the invasive perennial weed.
Much of Wales – along with London and the north-west of England – is especially hard-hit, with three places in the top 10 for the most badly affected locations.
Llanelli was sixth, with 389 occurrences within 4km.
Only Capel Garmon in Conwy was affected worse by the issue in Wales with 398 occurrences near the village.
Swansea was also among the most badly affected areas in Wales, with 333 occurrences. There were 361 occurances in Cardiff to place it seventh. The most badly affected area in the UK, however, is Bolton, with Bristol coming in second.
The interactive map has taken data generated from over 50,000 known infestations, with new sightings being added daily.
Japanese knotweed is native to Asia and was initially brought to the UK in 1850. The box in which it was brought was taken to Kew Gardens and, at the time, was sought-after for the flowers it produces. However, due to its fastgrowing roots, which can grow to be three metres deep and seven metres horizontally, it can now be found all across the UK.
During winter, the plant dies back to ground level but its bamboo-like stems emerge by early summer and can shoot up to over seven foot in height, suppressing all other plant growth in the process. The weed is notorious for being hard to remove by hand or with chemicals.
Now, legislation covers the control of the plant – an amendment to the Anti-social Behaviour, Crime and Policing Act 2014 includes invasive non-native plants including Japanese knotweed. While it is not illegal to have the weed in your garden, you should aim to control the non-native plant on your property to prevent it becoming a problem in your neighbourhood.
If it has a “detrimental effect of a persistent or continuing nature on the quality of life of those in the locality”, the legislation could be used to enforce its control and property owners may be prosecuted.
The Royal Horticultural Society (RHS) suggests speaking to neighbours directly where problems with Japanese knotweed occur in neighbouring gardens, and that these informal steps should be taken before contacting your council to talk about action under the legislation
According to the RHS, homeowners can consider control themselves for a small, isolated clump. However, a specialist professional company will be skilled at control, ensure eradication and can dispose of the plant waste at licensed landfill sites. Digging it out
without professional help, even if it’s feasible, creates problems over disposal as the plant is classed as ‘controlled waste’ under the Environmental Protection Act 1990. This requires disposal at licensed landfill sites. Japanese knotweed should not be included with normal household waste or put out in green waste collection schemes. Specialist Japanese knotweed contractors must be registered waste carriers to safely remove the weed from site, but check first before employing their services. Alternatively, it can be destroyed on site by allowing it to dry before burning.