Japanese knotweed is a plant species native to East Asia and was introduced to the UK in the 1800s.
It can grow up to four inches a day and forms dense thickets, which can kill native plant species and damage buildings.
According to invasive plant experts Environet, it is now widely recognised as a “pest species that outcompetes native plants and causes damage in the built environment”.
Using Environet’s data map, we have taken the average number of Japanese knotweed sightings from five postcodes in each area around Sutton to provide an average number of sightings for that area in the past 10 years.
Carshalton (SM5) had the highest number of sightings this year, with an average of 502 in each SM5 neighbourhood, followed by Central Sutton (SM1), which averaged 448 sightings per neighbourhood.
Wallington (SM6) had an average of 448 sightings.
Cheam, North Cheam, and Sutton Common (SM3) registered 355 average sightings.
The SM2 postcode, which covers Belmont, South Sutton, and South Cheam, had the lowest number of registered sightings, with 284.
Environet director Emily Grant said: “By mapping verified sightings, we’re helping people understand the level of risk in their local area and encouraging early identification and treatment.
“Vigilance is the best way to protect your property from Japanese knotweed, making sure you tackle it as early as possible before it becomes well established.
“At this time of year, knotweed is in full growth mode and easy to spot with its bright green heart-shaped leaves, which grow in a zigzag pattern up the stems.”
“Mature plants flower around August, when they produce clusters of tiny white blooms.
“If it is knotweed, a survey will determine the extent of the infestation and the best way to treat it, whether that’s digging it out of the ground, herbicide treating it or a combination of both.
“Public engagement is key in the fight against knotweed, and by reporting new sightings, homeowners can play an important role in controlling this invasive plant and protecting property values.”
