Call to be vigilant over Japanese Knotweed and Giant Hogweed

DESPITE improvements in tackling issues with Japanese Knotweed and Giant Hogweed, residents need to remain vigilant and report any sightings to Warrington Borough Council, says Cllr Nigel Balding, who raised concerns last year.

Last year Warrington Borough Cllr. Nigel Balding (Birchwood) campaigned for a better approach to dealing with the problems of Japanese knotweed. In Birchwood, two main patches of plants were of concern, one growing at J11 of the M62 and another beside the Birchwood Brook footpath.

After discussions with council officers, he was pleased to report that Warrington Borough Council had updated its policies for treating Japanese knotweed and Giant Hogweed, with a new regime comprising of an annual four-treatment plan.

The council has said that the costs of treating these two notifiable species on its land between 2017 and 2021 have increased from £2,430 to £6,885 stating “The increase in costs reflects the increase in locations treated for the two weeds”.

Following a question from opposition Conservatives last year, WBC published locations where Japanese Knotweed and Giant Hogweed had been identified (see table 1 below). These locations are all on council-owned land and include places in council wards from Appleton to Rixton & Woolston.

Cllr Balding says costs reported for Warrington seem relatively low compared to the national picture. In 2010 the estimated costs for treating Japanese Knotweed nationally were £166m and it is widely reported to have cost £70 million to clear from the Olympic Park in East London during building work for the 2012 Olympic Games.

Cllr Balding thinks that with a more rigorous herbicide treatment programme in place, Warrington locations should now gradually be cleared. However risks from spread from land not owned by the council or fly-tipping of building materials remain, even though it is an offence under the Wildlife and Countryside Act 1981 to allow these weeds to spread onto anyone else’s property.

With the growing season now in full swing, Cllr Balding is asking residents to report any council locations which are not on the known list. The sooner they are identified the easier it will be to treat. CLICK HERE

Of the two plants, giant hogweed (Heracleum mantegazzianum) is the one that is most dangerous. The sap of giant hogweed is phototoxic and causes phytophotodermatitis in humans, resulting in blisters and scars. It contains furocoumarin, which makes skin extremely sensitive to sunlight. If the sap gets onto your skin and it’s then exposed to the sun, your skin can blister badly. Blistering can then recur over months and even years.

Councillor Balding recently reported an isolated giant hogweed plant in Croft to the landowner Biffa (photo). This is the second case in two years, as he reported another plant in 2021 which the company successfully dealt with. He is urging residents to look out for the plants at this time of year and report them asap before they can cause any harm.

While Japanese Knotweed is not harmful to humans the plant’s vast root system exploits weaknesses in building foundations and drainage systems, often making buildings structurally unsound.

 

Table 1 Locations of Japanese knotweed and giant hogweed on WBC land 2021