Property Doctor Japanese knotweed

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Property 41

Japanese knotweed By Chris Ennis FRICS

As I write, I note that trees are budding, and in just a few short weeks, spring will with us. ‘Not before time’ I hear you say. Watch out for signs of Japanese knotweed! I have seen this destructive plant in Findon, and also growing by the roadside in Angmering. Japanese knotweed is a highly invasive non-native plant that has the potential to damage buildings and overpower native species, eventually eradicating them from their own environment. It is prescribed under the Wild Life and Countryside act 1981 which makes it an offence to allow the plant to spread. All parts of the plant and any soil contaminated with the rhizome root system are classified as controlled waste and have to be carefully destroyed. So what does it look like? In the spring, young purple/ red asparagus like shoots appear which turn green as they age. Some plants leaf initially, but can grow 50 cm as a straight rod.

In the summer, the shoots turn into bamboo like hollow stems, with regular swollen red joints and nodes. Stems can grow up to 3 metres in height. Leaves are lush green and can be described as heart shaped. In the autumn, flowers bloom 80-120cm in long clusters of small white / green flowers which start to fall in the late autumn. In the winter the stems turn brown / yellow and eventually fall off at about the time of the first frost. This is a difficult plant to eradicate. The root system can regenerate from small fragments of rhizome and can remain dormant in the soil for four years or more. The roots may spread up to 7 metres from the plant, and up to a 1 metre deep. If left untreated it can spread rapidly at a rate of up to 15cm a day and cause damage to paths, roads, driveways and foundations. It may well affect the suitability of a property for a secured mortgage advance. There are specialist companies that deal with eradication, but their services can be costly and time consuming. A proprietary glyphosate weed killer like ‘Roundup’, carefully applied will kill the weed, but it is (I am told) a long process. Chris Ennis FRICS email: surveyor1@talktalk.net 01903 261 217 or www.propdoctor.co.uk

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