I went to look at a really good job today, only to discover the dreaded Japanese Knotweed!
This horrid weed has become the curse of the countryside since its introduction as an ornamental plant in 1800s.
What is it? Well this plant forms dense clumps of undergrowth, reaching upto 3 meters in height. Its large oval green leaves and hollow stem (like bamboo) is a give away, as are the reddish shoots which appear in the spring.
This plant grows at an alarming rate – up to 20mm per day in any type of soil. In the autumn it seeds (luckily sterile) and dies back soon afterwards. It spreads through a system of roots which grow several meters from the main shoots. It also spreads vegetatively ie new plants are created from fragments of existing plants, the real danger of this weed.
It is an offence under the Wildlife and Countryside Act 1981 to plant or otherwise encourage the growth of Japanese Knotweed. This could include cutting the plant or roots and disturbing surrounding soil if not correctly managed.
Any Japanese Knotweed polluted soil or plant material that you discard, intend to discard or are required to discard is classed as controlled waste and must be accompanied by appropriate Waste Transfer documentation.
Spraying and mass root removal are the only effective means of control, following strict guidelines.
In my opinion, control, disposal and removal should only be done by experts to ensure you are conforming to EA regulations, thus avoiding prosecution.
What should you do if you think you have some? Cordon off the area & contact the Environment Agency without delay