In article ,
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Hi,

I've spent the last week digging and sifting the rhizome system of an infestation of Japanese knotweed.

however I've now come up against the fact that it is running underneath the driveway/patio.

I thought i had caught it before it would have spread there (and indeed it is relatively clear) however there was one 'crown' perhaps a meter at the closest point to the patio and as a result there two main roots heading off directly underneath the driveway and patio.

I'll take the bricks and patio slabs up if nothing else presents itself but if anyone has any help/tips for removing/killing a root system underneath non-diggable area it would be *greatly* appreciated.

T

https://www.rhs.org.uk/advice/profile?PID=218

We eradicated a wall to wall solid infestation of JKW from a son's
garden by cutting the lot to ground level (in full growth)then
persistently cutting off ALL new growth at a couple of inches high
before new leaves opened, so it couldn't photosynthesise and slowly
starved its root system to death. It took a couple of seasons.

Remember you can't legally bin or move JKW waste off your premises ;
best to just dry it and burn.

Janet.