Where ...?March 9th 2016
They seek it here, they seek it there …but where will the elusive Japanese Knotweed be found?
Okay, okay…. it’s not quite the Scarlett Pimpernel ….and lets be honest it isn’t that ‘elusive’…so you’d pretty much find it anywhere?
Well not quite.
There are clues that will get you pointing in the right direction…
Many people imagine that Japanese Knotweed is… ‘taking over our countryside’…well – in some places it is – but usually this will have started from a point along a river or a railway – some sort of linear route will be the point of origin.
Then when you start looking closely at this ‘point of origin’ you will see other formative factors – usually concluding that MAN has caused the infestation.
For years I couldn’t understand why knotweed would often be associated with the utility companies?
Why would a new infestation appear beside some new excavation for water pipes or a new gas-main? Was the knotweed simply lying dormant waiting to be awoken by the machinery or was the machinery somehow bringing the knotweed to the site….?
Hmmmm…maybe I need to contact Mulder and Scully and open an X File?
There’s nothing alien going on and it’s not rocket science either – once you see how the utility companies carry out their works and quickly move on to the next project – without cleaning the machinery…you begin to get a hint as to what’s happening.
Small fragments of viable knotweed are being moved from one site to another on the excavators and dumpers on the tracks or held on the chunky tyre treads – these simply fall off and get buried on site during works then start growing and rapidly spread.
Why do new infestations often appear along rivers?
This is a pretty easy one – obviously during times of flood,viable knotweed will be broken off and drift downstream only to end up beached on the riverbank when the floodwater subsides. But why …you may be asking…was it on the river bank in the first place? Well …there could be a variety of reasons for this – but just putting a couple of thoughts in your head:
Japanese Knotweed was used by the Victorian landscape designers in wetland settings to create a lush mature looking garden. During times of flood these wetlands and lakes would often overflow into watercourses taking fragments of knotweed with them.
Japanese Knotweed was also planted on purpose by the rivers authorities to stabilize embankments
Why do we get large stands of knotweed on the side of railway tracks?
Again a pretty easy one – railway engineers used Japanese Knotweed to stabilise unruly piles of stone on their embankments adjacent to the railway tracks. The plant has then rapidly spread causing huge problems to both Network Rail and to adjacent land owners.
What I find fascinating with the spread of this intrusive alien is that everyone seems to think that the plant is the most aggressive of invaders and that ‘accidental introductions’ have caused all of our problems….
It would however seem that …’accidents’…have little to do with the spread of Japanese Knotweed …pretty much anywhere that ‘man’ has had an impact…. you WILL find our least favourite plant.