New data has revealed the Pembrokeshire hotspots where Japanese Knotweed, the UK’s most invasive plant, is running wild.

The invasive plant species is responsible for damaging homes, pavements and drains and can spread up to seven metres horizontally.

As the Japanese knotweed growing season gets underway, invasive plant specialist Environet UK has revealed the knotweed hotspots for spring using data from its online map.

There are currently almost 55,500 known occurrences of the UK’s most invasive plant.


Western Telegraph:

The areas around Cwm Gwaun and Fishguard are the worst impacted areas in Pembrokeshire according to the map, where there are up to 220 occurrences of Japanese Knotweed in a 4km area in some places.

How to spot Japanese Knotweed

Knotweed hibernates over winter but in March or April it begins to grow, with red or purple spear-like shoots emerging from the ground which quickly grow into lush green shrubs with pink-flecked stems and bamboo-like canes.

For homeowners, the plant can pose serious problems if left unchecked, with the potential to grow up through cracks in concrete, tarmac driveways, pathways, drains and cavity walls.

The roots can grow as deep as three metres and spread up to seven metres horizontally. While serious damage to property is rare thanks to regulation which requires knotweed to be dealt with, it commonly impacts use of the garden, causes legal disputes between neighbours and can impact a property’s value by around five per cent.

What to do if you have Japanese Knotweed

The first step to tackling the plant is to commission a professional Japanese Knotweed survey and find out the extent of the infestation. They will be able to tell you where it originated, and the best way to tackle it.

Professional treatment should then be organised, which usually involves the use of herbicide for excavation of the infestation.

If you’re buying a property and you want to be sure it’s clear of knotweed, particularly if it’s located in or near a hotspot, arrange a detection survey.