Jul 232009

Japanese knotweed shoots

I was just sent a link from the BBC online news:


Jams and pie 'solution' for weed

Japanese Knotweed poisoning. Picture: National Trust
Only plants not controlled by herbicides should be used

Harvesting and eating Japanese Knotweed could be the best biological way to control the "nightmare" weed, a woman in Cornwall has said.

Caroline Davey from St Buryan said the shoots of the plant, which taste like rhubarb, can be used in jams, chutneys, crumbles, pies and even cocktails.

Scientists and gardeners have spent years trying to control the weed, which has no natural enemies in the UK.

"We can get rid of it by eating it and it's delicious," Ms Davey said.

The National Trust recently completed a three-year project to clear the weed from a seven-mile (10km) area of the Tregeseal River and the Kenidjack Valley in Cornwall using a herbicide.

It does taste just like stewed rhubarb and knotweed crumble is delicious
Caroline Davey

Japanese Knotweed was introduced to the UK from Asia by the Victorians as an ornamental species, but it has become a major environmental problem across Europe because of its "invasion" of habitats, excluding plants, eroding river banks and damaging structures.

Ms Davey, who runs foraging and cookery courses, said she discovered the benefits of eating it on a US website.

"In Cornwall it's known locally as donkey rhubarb," she told BBC News.

"You can substitute it for almost any rhubarb recipe. It does taste just like stewed rhubarb and knotweed crumble is delicious."

Untreated areas

The plant is recognised for its medicinal qualities in many countries and the edible shoots can be harvested in March and April before the leaves form.

"As an ecologist, I spent many years telling people how to get rid of knotweed," Ms Davey said.

"But it's a huge resource and by encouraging the local community to harvest it and eat it could be the best way of biologically controlling it."

Ms Davey said it was important only to forage for the shoots in areas where the knotweed is not being controlled with herbicides.

She also added that any pickers had to be extremely careful not cause it to grow elsewhere or dump it because it was an offence to spread it under the under the Wildlife and Countryside Act 1981.


So, after this news article came out the head of the Knotweed Forum at Cornwall County Council left me a message asking if 'we're singing from the same hymn sheet.'  So here is some extra advice and a few words of warning to prospective pickers and eaters of the superweed.

It is a scheduled weed listed under the Wildlife and Countryside Act 1981 and it is an offence to cause it to spread in the wild.

It can regenerate from a piece of rhizome the size of your thumbnail.  It is extremely invasive and even small pieces inadvertently picked up by your boots can spread it.

It is illegal to dump it or enable its spread in any way.

Therefore, if picking it to eat you must take extreme caution that you do not allow it to be spread in any way.

Always take any pieces with you in a sealed container.  Never drop any on the way home.  Never put any in your compost or throw any in the garden or on the side of the road.

Never, cut knotweed and leave it, especially alongisde water courses.

Always brush your boots off with a stiff brush to make sure you aren't treading any away from the knotweed site.  Check your car or vehicle doesn't have any knotweed on its tyres.

Furthermore, always check if the site has been sprayed with herbicide or not.

If you've done all that then you can go home and cook it and enjoy it.

Any bits you don't eat boil up in a pan and kill it before you dispose of it. 

This weed is the clone of one single female plant and reproduces vegetatively – it is a really strong weed – called 'itadori' in Japanese which means 'strong one'.

It has medicinal as well as culinary properties.

Substitute any rhubarb recipes for knotweed.  Knotweed should be harvested in Spring (March-May) when the new spears (looking like reddish-green asparagus) come up. 

Knotweed spear

Enjoy  x

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