JAPANESE KNOTWEED
WHAT IS IT AND WHY IS IT A PROBLEM?
JAPANESE KNOTWEED, or Reynoutria japonica is a perennial plant brought into the U.K in the 1800's by the plant hunting Victorians, who thought it was an attractive ornamental and well deserving of a place in the garden. What they weren't aware of at the time was its capability to spread rapidly, grow through seemly inpenetrable structures and suppress the growth of indigenous species.
Although it can be mistaken for other garden plants such as Leycesteria formosa and Houttouynia cordata, the details below should help you identify knotweed in your garden.
As growth develops the stems mature into something resembling bamboo, wth red speckling on the stems and fresh green leaves opening out into a flattened heart shape.
The young shoots emerge in mid-spring and can be a strong green/red, with curled up leaves resembling something like asparagus
The mature leaves darken to emerald green and blend easily with the surrounding flora
The key difference between Japanese Knotweed and leycesteria formosa, in particular, is the appearance of the stems in the winter, knotweed is a perennial plant and therefore it grows up in the Spring and Summer and dies back in the Autumn, leaving dead brown stems. Whereas leycesteria is a deciduous shrub and drops its leaves but retains bare vivid green stems.
LEGISLATION
In recent years Japanese Knotweed has become a growing concern for homeowners and morgage providers, whilest legislation regarding this pernicious weed is very clear:
You must not cause Japanese knotweed to grow in the wild.
If you have Japanese knotweed on your property, you must not allow it to spread into neighbouring properties. It would be classed as a private nuisance and you could be prosecuted under civil law, resulting in financial penalties. leading to a great number of refused mortgages and devalued properties.
Bearing all of this in mind, it is important to acknowledge many mortgage providers are relutant to lend on a property, to the extent that their surveyors have to ask directly if there is a presense of Japanese Knotweed, in your garden or nearby boundaries. (nb we always advised answering "yes" to this question, avoidance early on can lead to messy legal action if undeclared). If the surveyor reports that they considered there to be a real and definite risk of damage to the property by Japanese Knotweed, then you will want to contact us on info@papaver.co.uk to discuss treatment
Treatment
Our fully insured NPTC qualified consultant(PA6 AW INJ) will visit the site to determine the presence of knotweed, and assess the site to determine any risks and the most effective form of treatment. More often than not we use a system that delivers a single dose of herbicide directly into the stems of the plant, this advance technique limits the negative impact on surrounding wildlife and ensures as much of the product is delivered to the root system as possible.
Here are a couple of recent successes with no regrowth in the year following treatment
