The hotspots for an invasive plant species in Oxfordshire have been revealed.

Japanese knotweed is native to East Asia and was introduced to the UK in the 1800s where it has since spread out of control.

It can grow up to four inches a day and forms dense thickets which can kill native plant species, making it particularly harmful to the Oxfordshire countryside.

In the county, Oxford, Henley and Banbury are the worst affected locations according to brand new data from invasive plant specialist Environet.

READ MORE: Invasive plant species booming across Oxfordshire due to recent rainfall

Japanese knotweed has been spotted across Oxfordshire.Japanese knotweed has been spotted across Oxfordshire. (Image: Property Care Association)

Environet reports 44 instances in Oxford, 13 in Henley, and eight in Banbury and Abingdon while noticing seven in Wallingford.

There are a total of 122 verified knotweed sightings in Oxfordshire, or 0.05 incidences in every 1km², with Oxford by far the worst affected location in the county.

Over the next few weeks, knotweed will start to die back as temperatures cool and light levels drop, sending the plant into its dormant winter phase.

Its green leaves will die and fall from the branches, the stems will turn brown and brittle, and after the first few frosts, the plant will have completely died back, leaving only the dead canes remaining.

However, the plant will re-emerge next spring, so autumn and winter is the ideal time to excavate it when the garden is not in use.

READ MORE: Big spiders enter UK homes as tarantulas seen

Oxford is a hotspot.Oxford is a hotspot. (Image: Environet)

Tackling knotweed costs the UK economy nearly £250 million a year and homeowners are one of the groups most at risk not only from potential damage to their property, outbuildings and gardens but also from legal risks arising from encroachment or when properties are sold.

Whilst it is not illegal to have knotweed growing on your land, legal disputes can arise when it is allowed to spread across property boundaries and when sellers fail to declare it to buyers.

Emily Grant, director of Environet, said, “With over 60,000 known infestations of Japanese knotweed on our heatmap, we have a clear picture of its prevalence across England.

“Knotweed is easily identifiable during summer, but it’s a perennial plant. As we head through the autumn and into winter, the above-ground growth dies back and becomes much harder to spot.

“The best way to protect your property is to be aware of the risks and ensure you can identify knotweed at different times of the year.

READ MORE: Opening date for new Toys R Us store revealed with freebies to be given out

“If you do have knotweed on your property, it’s wise to act immediately to treat or remove it before it has the chance to spread further.

“With professional assistance, knotweed can be dealt with and the value of a property largely restored.

“If you’re buying or selling a property, consider instructing a Japanese knotweed survey to check for any sign of the plant on the property and its surroundings.”

Help support trusted local news

Sign up for a digital subscription now: https://www.oxfordmail.co.uk/subscribe/

As a digital subscriber you will get:            

  • Unlimited access to the Oxford Mail website        
  • Advert-light access             
  • Reader rewards             
  • Full access to our app