Fears as invasive plant that destroys homes spreads across the US

An invasive Japanese plant known to grow up to 15 feet tall has started taking over gardens across the US and threatens to catastrophically devalue homes in the North West, Midwest and North East. 

To the eye, Japanese knotweed is a beautiful plant with pretty white flowers and vibrant green leaves that are seen along roadways and in backyards. 

But in reality the plant, which is bamboo-like, has the ability to crack pavement, kill surrounding species and cause home values to plummet, according to the Wall Street Journal. 

The species can grow at the pace of three feet a week, and it takes years and extensive work to eradicate it from properties, even when its stalks are injected with pesticides. 

'You have to respect this plant,' Robert Naczi, a curator at the New York Botanical Garden, told WSJ. 'They’re known to grow inches per day in the spring.' 

Caitlin and Paul Maher Jr., of Lubec, Maine, had no idea the eight-foot-tall plant growing on their land of their newly bought home was Japanese knotweed in 2020, or how much of a fuss it would be for Paul to get rid of it. 

'It was a Vietnam jungle. I couldn’t even walk through there. It was impenetrable,' he told WSJ. 

After years of mowing it down, burning the stalks, leveling the ground and scything the plant, which left him with a torn rotator cuff, he's gotten most of it to go away, but he's yet to declare a victory. 

From time to time, he has small portions of the plant pop up that he has to treat. 

He likens the sprouting weed to a nuclear war survivor. 

'I don’t think it’s a coincidence,' he said. 

'I call it plant consciousness.' 

To get rid of a small portion of the plant, Dr. Bernd Blossey, a professor at Cornell University, recommends mowing it repeatedly to keep it in check - or dig it up to completely get rid of it. 

However, digging it up comes with its own challenges as you have to get the entire root out to make sure it doesn't grow back. 

And the process of digging it up again and again will take years before it's completely gone. 

Another method is to cut the plant down after it flowers and inject the stalks with herbicide using a tool that looks like a 'little pistol with a syringe on top,' Blossey said. 

If a Japanese knotweed victim doesn't destroy the plant, the weed can uncontrollably spread, disrupt ecosystems and form dense thickets that can harm local wildlife, according to CNY News. 

Indeed, the plant has become one of the most invasive and destructive plants in the UK, where homeowners have to disclose whether or not they have the plant - and can take insurance out to protect against it. 

Until recently, some UK banks wouldn't give people mortgages for their homes if the plant was on the property. 

Residents who have the plant on their property are encouraged to take out a five- to 10-year insurance policy on the weed for treatment and maintenance, according to WSJ. 

In the US, the Department of Environmental Conservation at the University of Massachusetts Amherst released a bug called Aphalara itadori after receiving permission in 2020. 

It is Japanese knotweed's worst enemy, and scientists have been placing them on individual giant knotweed plants and netting them to make sure they get the job done. 

'I’ve never been so excited to see a plant suffering before,' Jeremy Andersen, a research assistant professor at the university, told WSJ. 'They looked like their life essence had been sucked out of them.' 

Although the bugs aren't doing as well on Japanese knotweed, scientists are testing a new bug from a colder part of Japan that they hope will adapt to Massachusetts' climate better, Andersen said. 

The plant was first introduced to the U.S. from Japan in the mid-1800s by botanists who also brought over kudzu and oriental bittersweet, according to WSJ. 

It has since spread all over the U.S. and particularly likes watery areas with disturbed soil, like near roadways, according to CNY News.