Japanese Knotweed Management

Japanese Knotweed Management

When it comes to managing Japanese Knotweed, whether it is on a commercial site or within a residential garden, there is no‘one solution fits all’. Each stand of Japanese knotweed needs careful consideration, From the initial japanese knotweed inspection to the appropriate choice of control strategy to the consideration of options for waste control.

If you are a construction, landscaper/gardener or a property related professional, to help guide you through some of these considerations, we have below a series of support pages to help you.

However, if you are looking for qualified, experienced and professional help to manage your Japanese Knotweed problems, you can easily find a local PCA specialist happy to assist.

Find local specialists >>

Professional treatment options to manage Knotweed

There are many ways to manage Japanese Knotweed, ranging from long-term management through the use of herbicide sprays (usually for a minimum of three years) to faster, but more disruptive full-scale excavations using plant machinery.

Management by herbicide spray

For many, particularly residential sites,  a control program and subsequent management plan using herbicide spray is the most common and cost effective approach which causes the least disruptive method for Japanese knotweed management. 

However, Japanese knotweed rhizomes (in the soil) may not be entirely ‘killed off’ (eradicated) by such a programme and there remains a residual risk of re-growth (when herbicide-induced dormancy starts to weaken).  This risk can be off-set by the issue of Guarantees and these, when backed-up by appropriate insurance, are acceptable to most mortgage lenders. The risk of re-growth after ‘Completion’ of a herbicide management plan is greatly increased if the ground is disturbed by digging, so in practise such guarantees preclude any development work or landscaping in the affected area.

For professionals wanting to better understand the limitations, restrictions, and safety considerations regarding herbicide spray programmes, click on the buttons below. 

Using professional herbicides >>

Training: Safe use of herbicides >>

Management through excavation & burial

Another approach to Japanese knotweed management is to remove the plant and its extensive root/rhizome network from the soil completely*.  The key advantages of this approach are its speed and the fact that, once completed, the site is suitable for development.  

But excavation works can be extensive (Japanese knotweed rhizomes can spread many meters in all directions) therefore generating large volumes of waste soils which require further processing or disposal, all adding-up to greater costs not to mention the disruption.  

This approach is most common on commercial sites for obvious reasons, but is increasingly offered in domestic residential settings too (to enable extension works to start or the laying of new driveway etc.). 

For further details regarding Excavation and Disposal of Japanese knotweed, click on the button below.

Knotweed Excavation & Burial Page >>

Japanese knotweed - waste management

Japanese knotweed wastes arising from management activities will almost always be defined as ‘Controlled waste’ under the Environmental Protection Act 1990 and must therefore be handled and processed in accordance with the Environmental Protection (Duty of Care) Regulations 1991. This classification arises out of the fact that even tiny parts of the plant, especially rhizome fragments, can easily give rise to new plants wherever the waste is deposited, whether deliberately or accidentally.  Separate regulations apply if the soil etc. is also deemed to be Hazardous but this normally only arises on post-industrial sites.  

Waste Control - Stopping the spread >>