Streetlife

Ben K

How virulent is Japanese Knotweed?

We contacted an estate agency about a property that seemed too good to be true. And it was, the estate agency said it wasn't possible to get a mortgage on the property because of Japanese Knotweed.

We've seen some nice potential properties on the same street and adjacent streets. Maybe I'm being paranoid, but want to be sure, what's the risk of the knotweed spreading into properties in the vicinity? How virulent is it?

I've read up a little bit but any advice would be appreciated. Thanks!

Comments

Showing 1 - 25 of 33
Frances R
Very...read this http://www.dailymail.co.uk/news/article-2052337/Hertfordshire-couple-demolish-300k-home-rid-Japanese...
and thishttp://apps.rhs.org.uk/advicesearch/profile.aspx?pid=218
can be very expensive and time consuming to get rid of, the Olympic site cost of removing and disposing of Japanese knotweed is estimated at £70 million.
best to avoid
Ian Bull
It's most virulent and that's why it's reportable. I have a small outcrop of this to deal with, thankfully nowhere near home.

There are really only three methods of removal.

1) Continuous application of Glyphosate weedkiller. Possibly for a year or two.

2) Digging it up. Go down until you've got to the very bottom of the roots, preferably a couple of weeks after you've used Glyphosate.

3) Continuous cutting back to ground level. No plant can last if it can't gather sunlight. Expect to be doing this rigourously for years.

I could do the above so it wouldn't prevent me from buying a property I liked.

Best - Ian.
Dianne Meyer
I work in the property industry and thats one thing that makes people sit in fear It is the bane of all property and construction companies!! You laugh but it's the closest thing to triffids as humanly possible. Okay fine it won't attack you and attempt to kill you but once it's there you have serious problems. Not only will you not be able to get a mortgage but it is seriously difficult to get rid of. I think they have to put industrial acid there of sorts and nothing can grow there again for ages and the chances of it coming back are seriously high. I know massive construction projects have had to be scrapped due to knotweed. Sorry to hear about this being at a house of your choice.
Brian s
You also need to know its illegal to transport it unless to an authorised dumping place.  There are none in London.  It will grow from a sliver caught in your finger nail.
6rb
Had it in my back garden when I arrived 25 plus years ago. The only thing to do if the roots are below cement or tarmac, as in my case, is to buy something like Tumbleweed if it still exists and EVERY DAY when it isn't going to rain go out ans spray it.  I have a cul-de-sac behind me and I found it on the other side of my fence and of my neighbours fences and I sprayed and sprayed and sprayed for two years.  It went but is now back in a neighbour's garden so I am going in search of the strongest systemic number I can find.  Good luck.
Laura J
Whilst we re at it, any advice about Mares Tail? I gather it is one of the oldest plants in existence....
Rhona O'C
It is a classified plant that needs to be professionally eradicated - if you try to bin it yourself you could be in trouble.  We (our house plus the five contiguous gardens) had it until last year - it spreads very quickly (one clump reached the height of the fence, i.e. 6 feet, within a fortnight).  If it's within 15 metres of your buildings you won't get a mortgage; it can grow through concrete!  We used Knotweed Eradication Ltd; they're based in Knollys Road near Streatham and were fabulous.  It took 18 months with a series of six-monthly treatment, although Steve (the main man there) had warned that it could take up to three years.  Not cheap (it cost us ~£,2500), but the only way forward.  Good luck!
http://www.japaneseknotweederadication.co.uk/contact-us
Ben K
Thanks everyone - it's definitely bad! Sounds like people have had some bad experiences that we'd definitely want to avoid!

But I wonder if anyone has any knowledge of it spreading from one street to another? So we know a house on one street definitely has it but could it spread to houses on the streets on either side. Maybe it's just a coincidence that so many houses are for sale on these roads when they haven't really been sold for a while.

Any thoughts?
Brian s
The answer is yes! It will spread..and quite rapidly.  The advise given so far is good!  Good luck!!
Ben K
Ha - ok! We best look in a different post code then...that's horrible for the owners of all those properties.
cjdg
Ian Bull is right on his first recommendation.  His second poses the risk of contamination unless you burn it on the spot together with all the soil which is a waste of time and the third is likely to take a long long time.  I tried his order in reverse and only No 1 worked.  Took concerted action for three years in conjunction with two neighbours. 
I'm with http://www.pollocks.atics.co.uk/ and Pollock's Pennies UK presence
Carol R
When we bought our house 9 years ago, the "garden" was filled with Japanese knotweed.  I think we did use one of the companies authorized to remove knotweed initially, but it will keep coming back for a long time.  Round-Up does work (I think that is a glyphosate).  It travels down to the roots via the leaves.  At first we needed to apply it to new shoots every few days, but each year there was less and now there is none.
Agnes B
Alternatively, you could buy a goat. They eat everything, even japanese knotweed!
TB
Which street is it on ? Might be worth others knowing ..
Ben K
I thought about this myself but I don't want to worry/panic people when it's actually a non-issue. But equally I can see why it might be important for people to know. So I'm not sure.
fionapm
Do please let people know what street it's on, it's important to know so we can keep an eye out for it and do something about it if we see it.
Rhona O'C
It's not a non-issue at all.  Imagine working hard for years only to discover your property's non-saleable.  Please let people know.  You'd be doing a favour to neighbours who may not realise they've got it
Ben K
Or imagine you lived on a road and were selling your home and then someone posted on Streetlife that there was knotweed in that area, and your house became unsaleable.
Emma Y
Totally agree Ben. I do not think that you should post any details. If it costs a few thousand to eliminate then a house is not going to be unsaleable as long as it is treated before sale. Given how prevalent knotweed is meant to be, I have heard of relatively few unsaleable properties so I do not think that it is a big deal for people to get worried about.
Rosanna F
Ben K

........or imagine you buy a house with knotweed for many hundred thousands of pounds because  you were not told of the presence of knotweed in the area by the people on Streetlife that knew about it.
Sue S
Japanese Knotweed shoots are edible apparently. Like bamboo shoots. Not tried it...
Brian s
There are jam recipes for it too...
Jen M
We bought a house in March this year and found out later that the dreaded Japanese knotweed was hiding at the bottom of the garden between the shed and fence, hiding amongst bindweed, who's leaves look very similar. We have contracted a company to treat it for us, costing in total 1900 pounds over 3 years! They spray/inject twice a year for 3 years then guarantee it for 5 years.
It 'exploits weaknesses in buildings' which is the biggest fear, if it gets close to your house it is most worrying.
The other posts are right - you have to dispose of jkw as hazardous waste. If you try and dig it up, you risk spreading it everywhere.
It wouldn't put me off buying a house, but you may struggle to get a mortgage...
Once you know what it looks like, you'll notice it's everywhere in Wimbledon!
Spencer
Like
any risk, it’s all about proportionality and context. All problems that affect
property transactions, e.g.  cracking,
dampness and environmental issues like Knotweed etc  tend to have a spectrum of severity. As a
Building Surveyor I would have a duty of care to advise a purchaser of a
knotweed problem in adjoining properties but most importantly explain the associated
risks to spread, structural damage, value etc and what remediaition options are
available in the long and short term and the cost to implement these options.
Some of this advice and analysis will vary depending on the use of the property
e.g. family home, buy to let, investment etc. Armed with this info a decision
on whether to purchase should be quite straightforward.
Suzanne O'Donnell
My husband has found this company  - they import this product from the States - we thought it would be an easy solution to a small problem we have  - but the prices are something else !

www.steminjectionsystems.com

Any one want to set up in business with me, one of their kits and a van - Earlsfield Irradicators? te he!

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