Japanese Knotweed treatment services
There are several ways to treat and eradicate Japanese knotweed. They involve digging up the entire affected area and removing from site, digging up and burying on site or totally removing all of the affected area and the soil.
Other methods depending can be used depending on the size of the affected area.
Excavation and removal off-site (Dig and Dump)
A Dig and Dump operation provides instant eradication. The Environment Agencies 2013 (version 3) 'The Knotweed Code of Practice' puts emphasis firmly on reducing quantities of waste removed to landfill. With this in mind we accurately identify the full extent of the rhizomes and root system and in doing so ensure that only knotweed material – and not clean soil – is excavated and removed from your property (reducing your costs).
Excavation and burial (Dig and Cap)
Following excavation any remaining knotweed contaminated ground needs to be capped with a specialist knotweed root barrier to prevent re-emergence of the plant from underneath. There are two specifications of root barrier: Porous and Non-Porous. The correct specification most commonly depends on the drainage (water percolation) requirements of the installation area. The root barrier should be bonded to adjacent structures and/or overlie the affected area to remove any risk of knotweed re-emergence from underneath. In some situations it may be necessary to install sand blinding layers over and/or under the root barrier to prevent puncturing under compaction (from the construction activity above).
Stem injection is a method whereby herbicide is injected into the lower part of each mature stem of knotweed using a stem injector. Small knotweed plants cannot be treated with this method due to their size. There is some debate as to whether stem injection induces rhizome dormancy - making it look dead but not killing the rhizome system. We have other preferred methods of treating Japanese knotweed, such as herbicide application by foliar spray. We have worked on many sites which have been stem injected (by others) where it is evident that temporary dormancy had been induced as, after ground disturbance, significant regrowth was experienced.
Am I allowed to plant Japanese Knotweed?
By law, under section 14 of the Wildlife and Countryside Act of 1981, it's against the law to plant or cause Japanese knotweed to grow in the wild. It's not against the law to plant it in your own premises, however doing this may have a serious affect the value of your home.
The only herbicide approved for use in or near water which controls japanese knotweed is Glyphosate. For maximum effect, the plant should be sprayed at 6 l/ha from late summer onwards. Maximum effect is best when the plant is sprayed during the flowering period. Control is usually improved if the herbicide is applied to both the topside and the underside of the leaves. A nozzle that creates a 360 degree swath can be used to flood the leaves. The best method is to walk into the stand, start spraying and walk backwards away from the sprayed material. Large areas can be divided up by cutting pathways into the stand at 3-5 m intervals. Re-growth the following year will be much easier to treat. Herbicides containing Picloram (Tordon 22K), Imazapyr (Arsenal) and Triclopyr (Garlon 4)can only be used away from the waters edge. Regular inspections, preferably in May and August, of treated sites are recommended for at least two years with spot treatments on any surviving plant.