asked Her Majesty's Government:

What steps they will take to eradicate the spread of Japanese knotweed.

My Lords, in 2003, the cost of eradicating Japanese knotweed from Great Britain was estimated at £1.56 billion. Eradication is, therefore, beyond any realistic prospect. My department has supported research into the potential for safe biological control of Japanese knotweed. If successful, this could limit its growth or natural spread, and enhance the effectiveness of its management.

My Lords, I thank the noble Lord for that reply. It is 20 years since I first asked this question, and nothing much has happened. Does he accept that the 2-millimetre Japanese insect, Aphalara itadori, which is a type of psyllid, could more effectively control the spread of knotweed, Fallopia japonica, which can push its way through concrete? This is a real and considerable problem.

My Lords, the noble Baroness is right to say that it is a considerable problem. Japanese knotweed was introduced to this country in 1855, it has no natural enemies and it is a great nuisance in most parts of the country. From the research, I agree that there seems great potential in the psyllid she mentioned. This is a knotweed specialist whose juvenile nymph sucks the sap from the plants and is capable of causing significant damage to the knotweed plant. We are carefully considering this; some more research will have to be undertaken and undergo due process and regulation. Ministers will have to make the final decision, but I hope that it will not be another 20 years before we find a way to deal with this very nasty weed.

My Lords, does the Minister agree with the Government's estimate a year ago that dealing with non-native invasive plants costs the country some £2 billion a year? Does he also agree that 60 per cent of non-native invasive plants are escapees from gardens or garden centres? If he does agree, can he tell us how many of these non-native species are banned from sale and how the situation in England compares with that in Scotland?

My Lords, the noble Lord is absolutely right to suggest that invasive non-native species should be considered very seriously. That is why the Government, with the Scottish Executive and the Welsh Assembly, produced the Invasive Non-Native Species Framework Strategy for Great Britain in May. Because eradication can be very expensive once a particular species has taken root, the strategy ensures that measures are taken at a very early stage. That is the strategy that we are pursuing. My department is responsible for England but we work closely with the Scottish Executive on this.

My Lords, if no sanctions are available, are the Government considering introducing sanctions under the Wildlife and Countryside Act for anyone found to be spreading Japanese knotweed? Is the Environment Agency compiling a list of the sites that are currently identified and, if so, how frequently will it review that list?

My Lords, the situation is quite complex regarding sanctions. There is no statutory requirement for landowners to remove the plant but it is regarded as controlled waste and local authorities have powers to require landowners to clear up land that is adversely affected. The weed is listed in the Wildlife and Countryside Act, so it is an offence to plant it or to cause it to grow in the wild. Its illicit dumping is illegal. The Environment Agency can prosecute; there can be fines; and indeed, if it goes to Crown Court, imprisonment is a possibility. Most developers deal with this problem responsibly, although there are cowboys and it is clear that we need to take action against them.

My Lords, when I asked a Written Question about this matter on 25 June last year, I was told that the four-year scientific research project was due to report before the end of the year. I believe that that report is now on the Minister's desk. The Answer that I was given by the then Minister, the noble Lord, Lord Rooker, was that, if a proposed control agent is found,

"it will be necessary to produce a pest risk assessment and obtain a derogation from European plant health legislation", and that the Government would appoint a group of independent experts,

"to critically evaluate the research findings and data before any decision was made".—[Hansard, 25/6/07; col. WA 108.]

Can the Minister confirm that that is the process and that those are the actions that the Government are now looking at, to find a way of at least controlling this appalling plant? I remind the House that, because it spreads only vegetatively, it is in effect biologically all one plant and is said to be the largest female clone in the world.

My Lords, as ever, the noble Lord, Lord Greaves, is informative on these critical matters. A regulatory process has to go forward. My Science Quality and Priorities Team is commissioning a peer review at the moment. If, from the processes that the noble Lord has described, it is deemed that the risk is acceptable, Ministers can be asked to agree to the publication of an assessment for consultation with all stakeholders, and we then need to inform the EC Standing Committee on Plant Health. Clearly, very great care has to be taken in relation to the proposed use of a biocontrol agent but, on a positive note, so far the research looks very promising. We must hope that that is confirmed and that we can go through the regulatory processes, and Ministers will then be in a position to make a final decision.

My Lords, does the intergovernmental strategy that the Minister described cover Himalayan balsam, which is rapidly blocking many watercourses in England and Wales?

My Lords, I understand the concern about Himalayan balsam. My understanding is that an assessment of its impact is in progress using the UK non-native species risk analysis mechanism. We will be advised by the result of that assessment as to whether further action needs to be taken, but I assure the noble Lord that we are not complacent on this matter.

My Lords, further to the Minister's earlier response to my noble friend, has the research previously undertaken on the use of the insect to control knotweed been completed and is the research document on his desk, or he is saying that the research is starting as of now? If so, how soon are we likely to have the results?

My Lords, the first question I asked my officials was whether I could give noble Lords a timetable. I fear I cannot. This research is continuing, building on research that has already taken place. I can assure noble Lords that my department is not at all complacent. We well understand the problem of this weed. We are very anxious to do everything we can. In the mean time, there is guidance from the Environment Agency about current procedures, such as the use of chemicals, for dealing with the matter. We shall pursue this as quickly as possible, given the regulatory process through which we have to go.