Re: Japanese Knotweed
I found this on the internet
This method tho experimental may offer hope
In terms of control, Japanese knotweed is obviously extremely difficult. Digging the weed out is certainly the most environmentally friendly method; however, it is back breaking work considering the roots can travel so far and that the smallest rhizome can produce an entirely new plant.
In terms of chemical sprays, Glyphosate is the most viable option. Applied to the leaves, it is absorbed by the entire plant and is capable, after a few years, of killing this troublesome weed.
A relatively new option, however, is biological control using psyllid (plant-sucking bugs). Currently on trial, if this method proves successful, hopefully, it will be offered to gardeners up and down the UK.
TELEGRAPH.