Posted 3rd Jul 2017
Dr Paul Beckett fills us in on identifying and treating Japanese Knotweed
What is it?
Japanese knotweed is an ornamental plant introduced in the 1800s that has rapidly spread through root cuttings to most parts of the UK. It particularly affects urban areas where it can have a significant blighting effect on property values and cause damage to hard surfaces.
How do I identify it?
Key identifying features are as follows:
• ‘shield-’ to ‘heart’-shaped leaves;
• hollow stems; and
• alternate leafing arrangement, giving a ‘zig-zag’ pattern towards shoot tips.
Knotweed Treatment: Herbicide Spraying
The most cost effective treatment is herbicide spraying. However, the extensive root system means it will usually take a number of applications over several years to be effective.
Knotweed Treatment: Removal
Where a more immediate solution is required, such as developing a site for building work, the only option is excavation of the root system. The soil containing fragments of knotweed will then need to be disposed of to landfill.
However, volumes of waste can be reduced by careful screening of root fragments from the soil and using root-barrier membranes to segregate or fully encapsulate un-excavated roots underground.
Doing it Yourself Versus Hiring a Professional
Putting to one side the limitations on non-professionals’ use of herbicides and the sheer scale of potential excavations and waste arisings, the main issue in undertaking Japanese knotweed removal yourself is that you won’t be able to issue a suitable guarantee. This is very important, as without one you won’t be able to satisfy a future mortgage provider dealing with properties affected by your knotweed—i.e. not just your property, but also its transfer to a future owner and, potentially, neighbouring properties too.
Dr Paul Beckett is co-founder of Phlorum, a Japanese knotweed removal expert firm. He has a PhD in Plant Ecophysiology and has published numerous papers in peer-reviewed journals. For more expert information please visit: http://www.phlorum.com/services/japanese-knotweed/