To think this couldn't be possible?

[UhOhGuys]

Hey guys, I live rurally as does a friend near me. She doesn't have any immediate neighbours and Japanese knotwood is now growing in her garden. She is convinced somebody must have put it there.
Could this be possible?! Could japanese knotwood just magically spring up out of nowhere?
YABU: Yes this is possible, maybe someone did plant it
YANBU: No Japanese knotwood springs up all the time randomly

no one is going to randomly hop into a rural garden to plant knotweed.

Birds and other animals can also help to spread Japanese knotweed. If they eat the young shoots any stems of canes that pass through their digestive system could potentially send out new growth.

I mean, it’s possible that someone has tracked some down, taken a cutting, dressed like a ninja Percy Thrower, gone to her garden under cover of darkness and planted it in a plot to ruin her house, but it’s more likely that she’s being seriously paranoid and an animal has eaten some then pooed in her garden.

Has she got any enemies?

She thinks because of where it is (right st the bottom of her land) someone has planted it there so that they will be able to build over the top of it (something she has been resisting) because apparently building on top of it is the only way to kill it (?)

Knotweed can grow from a tiny fragment of root mixed in with earth or compost. If she has bought in new plants or earth or mulch, she could have bought in a fragment of knotweed too.

But it is not a crisis. Put roundup gel on the leaves and, if it is big, inject the stems with Roundup in the autumn. It is the only weed killer that goes down to the roots and kills h the whole plant. It might take time but it can be defeated.

Same way as brambles spread. Birds eat them and the seeds land on the ground wrapped up in fertiliser.

Also, building on top is a foolish thing to do with knotweed. It does not kill it and the knotweed will grow through the foundations of the building.

Building doesn't kill it. It's a threat because it grows through brickwork and destroys buildings.

Is your friend well in herself? She sounds anxious bordering on paranoid.

Is she always so paranoid? Sounds like she needs support with her mental health if she thinks someone would deliberately do that, it’s a very paranoid way of thinking.

Actually it's a cycle path they wanted to build nit a building. I am going around later to check it out, maybe we can tackle it by very regular weeding! I read about injecting it but doubt she would go for that, she's really anti chemicals

Can you gently encourage her to the drs too?

It’s spread by birds, river flow, train lines.

The river/stream growth seeds into the water and travels until it settles elsewhere.

The seeds get stuck to passing trains and likewise drop off eventually and grow where they settle.

She's being ridiculous. Seeds can be blown in on the wind. Like another commenter already said, they can come in with new soil or plants. If it's at the bottom of her land, then it'll have become a problem because she doesn't keep as close an eye on that area as she does on areas she sees whenever she leaves the house.

If she's anti chemicals then she's going to be stuck with it for a long time

"Knotweed can grow from a tiny fragment of root mixed in with earth or compost. If she has bought in new plants or earth or mulch, she could have bought in a fragment of knotweed too."

I have been helping my elderly neighbour get rid of JKW and this is exactly what the eradicating company told me and that its not brought in by birds.

Neither is building on it a good idea, building companies working on large projects are supposed to test for it and eradicate it if found as it will grow through concrete.

Anyway, I'm still paranoid about my neighbour's JKW but we're going in the right direction.

The chemicals thing is I think because she has gone to a lot of effort to have a lot of "untouched" wilderness so I can understand her not necessarily wanting to start injecting stuff. But depending on how bad it is if its newish maybe we can stop it before it gets out of control?

No new plants or soil brought in.

I sort of see her point in that this cycle path thing has been a bone of contention. But if you guys are saying that laying concrete down or whatever wouldn't kill it then I guess somebody having planted it on purpose doesn't make sense. I'll show her the thread

Japanese knotweed is spread by small fragments of rhizome - a classic means is when scraps get picked up in tracks of diggers and similar machinery, but tractor tyres could do it too.

It does not set viable seeds in the UK or Ireland because all our plants are female and the seeds cannot be fertilised. Luckily, or the problem would be a lot worse than it is.

Building over it won't kill it - it can travel many metres underground. Weeding won't kill it either - I'm very anti herbicide use in general cases, but I'd use herbicides on Japanese knotweed because they are the only thing that works (it has no natural predators in these islands). if she can afford it she should hire a trained and certified contractor.

There is very, very little "untouched" wilderness in the UK. People have been messing with the land for hundreds and hundreds of years.

As for chemicals, anything she would put on her garden is a chemical. Manure is made up of chemicals. Japanese knotweed is serious and she needs to understand that she should do whatever it takes to get rid of it.

There are many ways it can be transported to a site. It doesn't matter if there haven't been any new plants or equipment. Something will have transported it. Animals, the wind, workers on nearby properties, someone who has had it stuck in mud on their shoes who has walked in her garden... Many people in my area are dealing with it in walled-off back gardens. It's completely normal for it to get on to private property, unfortunately.

Does she ever feel like people are getting at her in other ways?

I think it needs to be professionally treated if she ever wants to sell the property.

If it is a cycle path that is being built, she is better off letting the LA know asap
plus have the department which maintains the public spaces looks at it and confirm what it is.
Most LA will have policy to actively manage it and that will include not carrying out works or moving material off the site.
The growth of plants and transportation of contaminated soil is covered under legislation.
As the plant is on the border of her land she has a legal obligation to stop it growing onto other peoples property.

Not managing it properly will result in the plants roots expanding underground at a rapid rate. And the roots can appear dormant for years so if the objective was to force a cycle path it was a very pooly thought out plan.

Weeding won't get rid of it the tiniest fragment left behind will regrow. The only thing to get rid of it is weedkiller

It can be targeted only on the knotweed - that's the injecting - so it won't hurt any other plants/wildflowers/weeds she's got growing there.