Blackburn with Darwen has been identified as the UK's worst borough for Japanese knotweed, with 2,135 incidences recorded, or 40.36 per square mile, according to a study by invasive plant specialists Environet.
The invasive plant, introduced to British gardens by Victorians, has spread out of control, causing significant damage and economic costs. It is estimated to cost £246.5 million annually, according to CABI.
Residents Express Concern
Homeowner Tony Dawson was shocked to discover Japanese knotweed growing just 50 yards from his back gate. "That's just 50 yards or so from where we are standing. That has me very concerned," he said. "Under our homes on this road is a natural, underground spring, which means we have to be careful about what goes on under our properties, which could affect the foundations."
Neighbour David Wilson-Parr, 52, who has lived on the road for 13 years, was alarmed to learn the plant was growing just beyond his boundary fence. He admitted to having taken a supplement made from the plant, but added: "I don't want Japanese knotweed near my garden. I've read about it as I researched the supplement before I took it, and was shocked by the speed at which it grows."
Spread and Impact
Japanese knotweed spreads up to seven metres below ground, can smash through tarmac, and even 1cm-long chopped roots can regenerate into new plants. It can grow up to 10cm a day in summer, reaching three metres in a single season.
Maurice Ffelan, 82, of The Friends of Blackburn Old Cemetery, said: "It's a bugger to get rid of. It can grow to 10ft tall." He added: "The problem is if you start mowing it, you transfer little bits about and you don't notice until the next year when it suddenly starts popping up everywhere. Spraying with weedkiller seems to be only partially successful, probably because of the dense root balls."
Expert Advice
Emily Grant, director at Environet, explained: "Japanese knotweed is the most problematic invasive plant in the UK. It's not just because of the damage it can cause and how hard it is to get rid of, but also because of the restrictions on buying and selling affected properties and the legal implications if it's allowed to spread."
She advised: "If you do discover knotweed on your property, it's best to act fast and get a survey as soon as possible. From there a treatment plan can be put in place, whether it's herbicide, removal, or a combination of both."
Council Response
Tony Watson, director of environment and resident services at Blackburn with Darwen Council, said: "Japanese knotweed is a national issue and not unique to Blackburn with Darwen. Where knotweed is present on council-owned land, it is actively managed through a targeted treatment programme."
Residents remain worried, with one elderly woman saying: "It's like the Day of the Triffids, like some alien plant that withstands anything. It's actually quite scary."
