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Japanese Knotweed

Volume 747: debated on Monday 8 July 2013


Asked by

To ask Her Majesty’s Government what progress has been made in eliminating Japanese knotweed in the United Kingdom.

My Lords, we commenced a controlled release of Aphalara itadori to tackle Japanese knotweed in 2010. The signs are encouraging for the establishment of this highly specialist psyllid. Aphalara successfully overwintered but numbers remained low and so additional releases were made in spring 2012 and spring 2013. No non-target impacts have been observed by the programme of close monitoring.

Will the psyllid really be enough to kill off this pernicious weed? There are increasing reports of wretched owners of land who have had their land affected by Japanese knotweed and have been refused mortgages. Why can we not give them natural Roundup which is unpolluted? I managed to kill off my knotweed a number of years ago.

My Lords, experience from around the world has shown that biocontrol tends to take five to 10 years from the initial releases to achieve effective control. Despite poor summer weather since its release, Aphalara has shown that it can survive in small numbers and overwinter in the wild here. The question is how we can encourage it to achieve survival in larger numbers.

My noble friend mentions mortgages, and we are aware that some mortgage lenders have become reticent to lend if Japanese knotweed poses a threat to the property concerned. We have undertaken some work to estimate the impact of this. The RICS believes that recent concerns by valuers and lenders are often based on misunderstandings, and it consulted on that in 2011 in order to help valuers and mortgage lenders to understand the implications. Cornwall council has also provided guidance for mortgage lenders.

On the use of Roundup, I understand that others have also had success with it. Of course, it needs to be applied with care, and we are also looking carefully at a couple of other possible biocontrol options.

My Lords, if the Government are not willing to legislate, can the Minister at least urge local authorities to co-operate locally? When a resident spots knotweed in an adjacent property, the local authority can be helpful in identifying the owner of that property so that something can be done about it. At the moment, some local authorities wash their hands of the problem.

Yes, my Lords. I understand the point that the noble Lord makes. We have to balance, on the one hand, a determination to control this odious invasive species and, on the other, an imperative not to unnecessarily penalise people who are simply not in a position to do anything about it. However, I take the noble Lord’s point.

I did not take in the name of the treatment—it was “apha” something—but is there any risk of it becoming like the Hawaiian cane toad of Australia and proving to be a menace in itself?

Yes, my Lords. It is called Aphalara itadori and my noble friend is entirely right. On top of research work that has already been done testing it against more than 90 plant species, we are going through a phased release over five years to make absolutely sure that it focuses entirely and exclusively on Japanese knotweed. That is a really important point.

My Lords, Japanese knotweed is frequently found on publicly owned land, such as railway property and council land. In view of the fact that the Government seem to be totally unable to enforce regulations regarding ragwort, how can any rulings be given on Japanese knotweed?

The noble Countess has a point but this Question is about the use of a biocontrol against it. She mentions Network Rail, which, as a matter of interest, is a member of the project consortium for the natural control of Japanese knotweed and is fully involved in discussions about how the trial proceeds. Along with Defra, it sponsored the Environment Agency knotweed code of practice, published in 2006. It has been a major funder of the research and was among the instigators of the project.

My Lords, the Minister will be aware that the Royal Horticultural Society calls this plant “a real thug”. It does so because of the immense damage that it does. There was a person in my neighbourhood whose house was worth £350,000 but was sold for £50,000 because the weed had invaded the premises. We are also well aware that Network Rail spends a very large sum of money every year protecting the permanent way from knotweed. I fear that the Minister is talking rather gently about a very severe problem, and I hope that he will inject some urgency into the Government’s response.

My Lords, I am aware of frankly tragic stories about people having trouble selling properties and obtaining mortgages, and I have huge sympathy for them. That is why this work is so important.

My Lords, I congratulate the noble Baroness, Lady Sharples, on her persistence in this matter, which is vital, and I congratulate the Government on the continuation of the experiments with the psyllid Aphalara itadori. Is it not the case that under the Wildlife and Countryside Act 1981 it is already an offence to plant or cause this species to grow in the wild? Is it not time that that was strengthened and that allowing this plant to grow on your land without taking steps to remove it became an offence?

My noble friend is certainly right that it is an offence to allow it to be introduced into the wild but we think that that is a step too far. It is a real challenge to get it under control and we want to find an effective biocontrol before we consider a move such as that suggested by my noble friend.

My Lords, can my noble friend say to what extent the spread of this knotweed has developed throughout the whole of the United Kingdom and to what extent the devolved Administrations are playing their part in trying to eradicate it?

That is also an important point. The Welsh Government are a member of the project consortium for the natural control of Japanese knotweed and have been a major funder of the research. The licensing authorities in England and Wales work closely together to ensure a consistent approach. We have kept the Scottish Government updated at key points in the project, although, to answer my noble friend’s first question, Japanese knotweed is not such a significant problem in Scotland.

My Lords, they are blessed with this psyllid, Aphalara itadori, and that is where we got it from. The issue is to ensure that it is as effective under our conditions as it is under Japanese conditions.

My Lords, is it not important that the Government take great precautions to prevent the importation of things such as Japanese knotweed? Such things do not just arrive; they are brought in. I know that there have been discussions at European level on the control of imports of plants; for example, Ash plants that might affect our trees, and many others. That is crucial because once Japanese knotweed gets hold, you cannot stop it.

My noble friend is quite right. A non-native species risk assessment of Japanese knotweed has been carried out under the GB non-native species mechanism. It is one of more than 50 risk assessments on plants that have been published. Japanese knotweed is assessed as high risk. There are many others. My noble friend will be aware that we are doing considerable work bearing down on pests such as this which are coming at us from abroad.

Will the noble Lord explain to those of us who are enthusiastic gardeners but have never seen Japanese knotweed what we should be looking out for? On a more serious note, is he confident that public information—for example, in garden centres and other places where people purchase plants—is at a sufficiently high level to ensure that people who should be aware of what to look out for know what they should be looking for?

My Lords, I quite agree with the noble Baroness that public awareness is one of the most important aspects. I will resist the temptation to describe the appearance of Japanese knotweed in front of your Lordships.

All right then. Defra is helping with the start-up of local action groups which are being established across England to reduce or eradicate invasive non-native plants, including Japanese knotweed. One of the objectives of these groups is to raise awareness of the environmental, social and economic problems that invasive non-native species can cause. They are raising awareness on a local and national scale with landowners, volunteers, potential partners and other interested parties. I should also say that information on GB non-native species is available on the secretariat website, which includes an identification sheet.