Oral question asked in the House of Lords, by Lord Davies of Oldham (Labour). It was answered on Thursday, 24 June 2010.

Japanese Knotweed

Question: My Lords, we on this side wish the Minister well in the attempt to control Japanese knotweed. Will he emphasise that it is not just gardeners and people who own cultivated land who are concerned about it, but our public services? Knotweed represents a heavy cost on our railway system because of the threat that it represents.

Answer: My Lords, the noble Lord is right to emphasise the costs, as did my noble friend in her supplementary question. It can cause major structural damage. We estimate that the costs of managing it are about £150 million a year but, as the noble Lord will remember from when he had to deal with the matter, back in 2003 the cost of total eradication was estimated at £1.5 billion. Now, obviously, it would be a great deal more. We should wait to see what this psyllid can do and whether it leads to a much better control of Japanese knotweed.

Secondary information