Japanese Knotweed

Smudgeismydog

We had our offer agreed on our dream house on 26th April, and then found out (via the Property Information Form), that the property has Japanese Knotweed on 10th May.

The current vendors had some treatment in 2022 and 2023 from a local environmental group (no charge), and after agreeing the sale, have arranged for further treatment this September, (our target completion date is mid August). However, the email trail I’ve seen clearly states it is the householders responsibility, and whilst the environmental group will come back in September, future support will very much depend on funding and contractor availability.

I had hoped that once the vendors were aware it was on site, they would have instructed a professional company to treat the JK and there would be guarantee in place, but instead it looks like they have tried to treat this themselves over the last couple of years 😬

I’ve asked our solicitor to either request that they provide us with information of any formal treatment they’ve undertaken along with guarantees, or if not, then to put this in place.

Whilst we are not purchasing with a mortgage, I am concerned that if this is not treated properly we could be left with a property we struggle to sell in the future, or that it will cost us a lot of money to sort out.

Would be very grateful for any guidance, experience or insights you might have
Thanks 

daveyjp

How much is there?  A single stand wouldn't concern me, half an acre would.

You also need to consider where is it coming from.  Is it a rogue plant or is it from a nearby much larger infestation such as waterway, railway embankment, derelict land etc where eradication would be very difficult?

Smudgeismydog

many thanks

In 2022 the DAFOR scale noted that it was low lying on both sides of the brook that passes under the cottage, and classified it as ‘frequent, which means 16%-30%. Apparently it has decreased, but I’m not in a position to validate this, particularly as the current owners have DIY treated, and note it is less visible.

Should also note I am aware there is JK in the area.

Dustyevsky

Dream homes don't come with thoughts of selling in the future, unless it's with the prospect of a substantial profit! For most of us, they arrive with problems, which we either decide to accept, or we let someone else have them.

JK can be treated, and in time, eradicated, but like subsidence, some stigma remains long after it's gone. The watercourse makes things trickier, but the treatment, glyphosate, is approved for use in watercourses.

For me, the matter of how the brook goes under the house is important. In a concrete or plastic pipe, no problem, but I'd also want to look at flooding potential & history. Assuming those yield satisfactory answers, I'd regard the JK as an extra expense and re-negotiate accordingly. As you say, a guarantee is better than the cheapo solution applied by the vendors.

Smudgeismydog

Thanks Dustyevsky, you’ve confirmed my thoughts

Sapindus

The watercourse also leaves you at greater risk of breaking the law by "causing or allowing the JK to spread" downstream.

Grizebeck

Found knotweed on house we brought last year.
No issue I am using agricultural grade glyphosate which will sort it out

Chemistry777

The bungalow we bought had a beautiful cottage garden.  Only once we moved in did I realise is was overrun, with Ground Elder, Couch Grass, Marestail, Bindweed, Lustraffe and Russian Vine.

It has been a real pain to get on top of this and took lots of hard work (and digging) but we love the house and even if we had know before hand it would not have changed our mind.

As someone stated above, every house will come with some challenge, and even though JK is a level up from my (minor) stuff, if you love the house and are determined you can manage and even erradicate.

daveyjp

The presence of any watercourse would be a concern as it means you will be eradicating the plant forever. Guarantees aren't worth paying for, especially where there are other areas nearby which won't be treated. Glyphosate is cheaper!

Dustyevsky

Chemistry777 said:

The bungalow we bought had a beautiful cottage garden.  Only once we moved in did I realise is was overrun, with Ground Elder, Couch Grass, Marestail, Bindweed, Lustraffe and Russian Vine.

Is that the German airborne version of Lythrum salicaria?

Chemistry777

Haha !!!! yes the German version except the yellow stuff.  Spreads like wildfire and proving difficult to get rid.