No one is in any doubt of the problems cased by infestations of Japanese Knotweed and its relatives. Nor is it just a European problem, it is also a serious nuisance in parts of the USA.

There are many different approaches to control but they all fit into three basic categories; mechanical, chemical and biological - and any permutation of the three.  A combination of cutting and herbicide is probably the most effective, but even that can take years in long-established stands.  Chemical control is expensive, not always 100% effective and can have a negative effect on the environment.  Physical removal of the rhizome can be successful, particularly on development sites where the whole infestation is accessible, but can produce large amounts of hazardous waste. This must be taken to deep land-fill sites suitable for the deposition of live Japanese Knotweed rhizomes, since it is an offence to knowingly spread this plant 'in the wild' (Wildlife and Countryside Act 1981).  Due to these problems there is now an increasing interest in the use of Biological Control.

An excellent review of control measures may be found in The Japanese Knotweed Manual.

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