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Japanese Knotweed

Question for Department for Environment, Food and Rural Affairs

UIN 212225, tabled on 28 October 2014

To ask the Secretary of State for Environment, Food and Rural Affairs, what steps her Department is taking to assess and mitigate the effect of Japanese knotweed.

Answered on

3 November 2014

It is well known that Japanese knotweed can have ecological impacts related to the alteration of habitat structure and biological communities, and can also pose some structural, management and access concerns if left uncontrolled. The plant is listed on Schedule 9 of the Wildlife and Countryside Act 1981, which makes it an offence to allow the plant to escape or cause it to grow in the wild. When disposing of contaminated soil from development sites it is a legal requirement that the spoil must be disposed of as controlled waste.

Since 2011, Defra has provided grant aid to several local action groups throughout England to reduce or eradicate invasive non-native species, including Japanese knotweed in local areas.

Additionally, Defra has funded rigorous laboratory testing to identify a possible biocontrol agent to control the plant and has identified the psyllid, Aphalara itadori. A closely monitored licensed trial release programme has been undertaken since 2010 to assess the impact of this psyllid, although no significant and sustainable impacts have yet been seen because only small populations of the psyllid have survived. This year the project has conducted caged field trials releasing larger numbers to establish higher population densities and we are awaiting the results.

The recent provision of Community Protection Notices, provided for in the Anti-social Behaviour, Crime and Policing Act 2014, are now available for use by local authorities to control or prevent the growth of Japanese knotweed.

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