Taking Action on Japanese knotweed on new Development Land

Japanese knotweed has been widely publicised in recent years and is now recognised as a huge problem for anyone whose land it decides to grow on. Despite the increase in awareness, there are still grey areas about land that’s due to be developed: Do landowners need a survey to identify Japanese knotweed? Does a property developer have an obligation to eradicate/control the Knotweed? Whose responsibility is it to get rid of Japanese knotweed? What are the best methods on a new development site? In this blog, we answer all these questions and shed some light for both those in the construction industry as well as new home buyers.


Can you Build on Land that Has Japanese Knotweed?


It may surprise you to learn that building can still go ahead even with a Japanese knotweed infestation present on a site. If the footprint of the development does not encroach the 4- 7 meter buffer zone for the knotweed infestation, then the knotweed could be treated in-situ with a simple herbicide treatment plan supported with a site specific Management Plan, including Completion Report and cert on completion of the control program. If the knotweed growth and rhizome is within the footprint then mechanical excavation will be required.

Typically our experts at Knotweed Control Ireland notice the main issue is that knotweed simply isn’t being identified prior to development commencing, and in many cases measuring the existing area of Knotweed present is carried out incorrectly.

Developers are not legally required to perform a Japanese knotweed survey, but we strongly advise that they do employ an invasive plant specialist to carry out an invasive plant survey prior to site enabling.

In theory, some developers could pretend they knew nothing about a Japanese knotweed infestation and still continue with legal building works, not wanting to delay work or take on the expense, but we almost always find that any reputable company simply wouldn’t behave so unethically.

To avoid the hefty bills for Japanese knotweed removal, as well as potential legal expenses for not dealing with it, it’s important that landowners get as much information as possible prior to purchase or development.

We strongly advise every developer includes a Japanese knotweed survey as a habitual part of their project planning and due diligence. This precaution can save an incredible amount of time and money later on.


What a Good Invasive Plant Specialist Should be Doing....


There are several main services that a good well experienced invasive plant specialist should be providing to his clients. Please see below for more information on this:


  1. An invasive plant specialist should understand the pros & cons of the various current Best Practice eradication & control methods, and alleviate clients concerns especially elderly clients that the presence of Japanese Knotweed on or adjacent to their property need not be a major worry/concern.

  2. Be able to recommend most suitable, economical, site specific eradication or control method to clients.

  3. Be able to pass savings on to a client by reducing Knotweed impacted soil volumes going for disposal on/or off-site. This is done by the correct identification of all viable Knotweed Rhizome, Crown, & Stem material.. and also removing no more and no less of this material.

  4. Reducing waste to landfill is also compliant to current Waste and Environmental directives, including the removal of .high impact invasive plants along waterways being beneficial for native Biodiversity.

  5. An invasive plant specialist should have a duty of care to protect important Pollinators (Bee, Wasp & Butterfly), local waterways and the general public. This is done by implementing strict compliance to current guidance in Integrated Pesticide Management, (IPM), including The Irish national Action Plan on Sustain Pesticide Use, 2011.

Written by Ronnie Murphy - Knotweed Surveyor - Knotweed Control Ireland.




Featured Posts
Recent Posts