Trees: British Ash Tree

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Monday 5th November 2012

(12 years ago)

Lords Chamber
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Earl of Selborne Portrait The Earl of Selborne
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My Lords, I thank all noble Lords who put their names down to speak in this debate, which comes at a slightly later hour than perhaps we expected. I declare an interest as chairman of a farming company that has woodlands and a fruit nursery.

The word “crisis” is often overused in the context of environmental concerns, but the sudden realisation that the British ash could go the way of the elm in the 1970s is without doubt the recognition of a crisis. I will start by setting out the facts as I understand them. I am sure that if I get them wrong, the many experts who are due to speak will be able to put me right. Ash dieback disease is caused by a fungus called Chalara fraxinea. The disease was probably introduced to northern Europe on nursery stocks from Asia. Over the past decade it has had a devastating effect on the ash trees of northern Europe. It was first confirmed in Britain in March 2012, on young ash trees in a nursery in Buckinghamshire. Subsequently, other sites of infection were discovered, linked to imported nursery stock from Europe.

Last month, ash dieback was identified in older, native trees in woodlands in East Anglia. I will bring noble Lords right up to date by saying that today the Forestry Commission and Defra reported that after a weekend of intense activity by volunteers and experts, Chalara had been identified in 82 locations, including 14 nurseries, 36 planting sites and 32 forests and woodlands, including some in Kent and Essex. Last Friday, the count was 52 rather than 82, so the expectation must be that as surveillance and monitoring extend, many more sites will be identified.

While cases of infection in nurseries are clearly caused by importing infected stock, cases in mature trees in woodlands in the east and south-east of England are thought to have been caused by spores that were blown from the continent, or which possibly were brought in by migrating birds. In August, the United Kingdom plant health authorities undertook a pest risk analysis on ash dieback, which concluded that once trees are infected, they cannot be cured. However, the analysis also stated that not all trees die of the infection; a number are likely to have genetic resistance. Swedish research suggests that this number might be significant.

The pest risk analysis formed the basis of a fast-track consultation that ended on 26 October. On 29 October the Government introduced a ban on ash imports and the movement of trees. At the same time, Defra’s Chief Scientific Adviser, Professor Ian Boyd, was asked to convene a tree health and plant biosecurity expert taskforce. A number of companies have proposed treatment solutions for Chalara, which Defra has promised its scientists will rapidly evaluate. So much for history; I recognise that this is almost a running commentary on a fast-moving epidemic.

The public reaction has been one of disbelief that once again we have been caught by surprise by yet another threat to a native tree species from invasive pests and diseases. After the disastrous outbreak of Dutch elm disease in the 1970s, when we lost more than 30 million elms to a new and more virulent fungus spread by beetles, we were challenged by a plethora of tree pests and diseases, including acute oak decline, which is of great concern, particularly in the east of England; plane wilt; chestnut blight; and bleeding canker of horse chestnut, to name just four from a much longer list. Time and again we seem to act too late. For all those diseases, as for ash dieback, we put in place policies once we had found that the diseases were already with us. What we need are measures aimed at keeping out these serious pests and pathogens and such measures need putting in place years ahead of the anticipated arrival of the disease.

We knew years ago that ash dieback was a threat. We discussed four years ago with the European Commission's standing committee for plant health whether an import ban might be appropriate, but it seems that we were not able to produce the scientific evidence to justify a ban then. Instead of a ban on imports, which we now have, we carried out a small-scale survey. By the time Defra launched its Tree Health and Plant Biosecurity Action Plan in October 2011, ash dieback seems to have been relegated to a low priority. Indeed, there were plenty of problems in this country on the tree health front to deal with. This allocation plan allocated £7 million over three years to tackle tree diseases. That is not just on research, but on all other measures that might together address these issues.

Ahead of that biosecurity action plan, the Forestry Commission produced in May 2011 a revised table of top pests and pathogens that threaten tree health in Great Britain—a list of about 16 species. This listed the prioritisation criteria for potential impact for each disease: its risk or probability of entry and its expected economic, social or environmental damage. Those were the right questions to ask. The problem is that having asked the right questions no one seems to have answered the questions correctly or alerted the Secretary of State that ash dieback, although not yet thought to be in this country, like many of these other diseases, was an imminent threat, that its economic, social and environmental damage could be enormous and that we should act immediately to ban imports of ash plants. Defra got permission for the ban in October. Why on earth could the scientific evidence for justifying the ban not have been produced three or four years ago when the Horticultural Trades Association and others were asking for a ban on ash imports?

We do have a taskforce convened by Professor Ian Boyd charged with reviewing our approach to plant health. Rather than dwell on our failures in protecting plant health let me list what this taskforce now needs to recommend. Landowners and the public need to be assured that whenever a suspected incidence of an infection of whatever disease is reported, a rapid identification service will be provided. Detection and identification methods using molecular approaches such as the portable DNA tests have undergone rapid development and tight targets for response rates must be set. We need greatly to increase the surveillance, monitoring and inspection of nurseries and plantations.

The Forestry Commission has lost a significant proportion of its staff in the field. Its regional staff used to be able to spend much more time in the woodlands and forests, and they knew their forests. Likewise, its research capacity has declined. Research on pests and pathogens of trees is woefully underfunded, whether in universities or research institutes, and bears no correlation with the cost to the economy of woodland pests and diseases or to their impact on society. An assessment must be made of eradication and containment methods for ash dieback and indeed for other diseases, reviewing the role of a quarantine system for plants and plant passports for species for which the import ban does not apply. We need to develop biological control approaches such as looking for natural enemies to these new pathogens.

Trees are a long-term crop and amenity. Our approach to this sudden threat must be long term. We need to recognise that within our ash population there will possibly be some strains of ash with resistance to dieback. We need to protect this diversity. I hope that the Minister will assure the House that tree health will in future be given the priority it deserves and that if the taskforce comes up both with short-term and long-term recommendations that command the confidence of experts, the forestry sector and the public, the Government will without reservation commit to implementing those measures.

Baroness Northover Portrait Baroness Northover
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My Lords, I remind noble Lords that, unlike previous debates this evening, this is a strictly time-limited debate and that, therefore, when the clock reaches six minutes, noble Lords have had their full time.

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Lord De Mauley Portrait The Parliamentary Under-Secretary of State, Department for Environment, Food and Rural Affairs (Lord De Mauley)
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My Lords, I thank my noble friend Lord Selborne and all noble Lords for their extremely helpful contributions in this debate.

The ash is one of our most recognisable trees and we have about 80 million of them in our country. This debate focuses on the dangers to them posed by Chalara fraxinea, but of course it goes much wider. I must declare an interest as a grower of trees, including ash. The Government are taking the threat posed to the British ash tree extremely seriously. Let me start by setting out very clearly the current situation, our scientific understanding and the action we are taking. Ash dieback is a disease caused by a fungal pathogen that has devastated ash across northern Europe. With ash trees representing 5 per cent of Britain’s woodland cover, the potential impact of this disease on our landscape is significant.

I am going to try to avoid being party political, but before 2010, the scientific evidence in Europe indicated that the organism responsible for ash dieback disease was one that was already widespread and native in Great Britain. This precluded the use of import restrictions as a means of control. In 2010, new scientific evidence was published which correctly identified the pathogen that caused the disease. Between 2009 and 2012 the Forestry Commission inspected 15,000 individual ash trees across the country located in more than 8,000 groups. Of these, 103 trees were discovered to be in ill health. None of these was identified as caused by Chalara.

In February 2012, a routine nursery inspection discovered Chalara, and this finding was confirmed on 7 March. Immediately, the UK plant health authorities deployed additional resources to carry out trace-forward inspections of material known to have been supplied from the infected nurseries. Over the summer, 1,000 at-risk sites were identified and 100,000 saplings were destroyed. In parallel, the authorities developed a pest risk analysis, required, as noble Lords know, as the basis for intervention. Once completed, this analysis was fast-tracked into a shortened consultation to discover the extent of Chalara in Great Britain. During this time, the industry instituted a voluntary moratorium on imports of ash planting material, and I offer it my strong thanks.

On Friday 26 October, this consultation closed. From the early afternoon of Monday 29 October, the movement of ash from anywhere that is not a certified pest-free area—right now, nowhere has that label—became a criminal offence in time for the start of the main UK planting season at the end of November. During the consultation period, Chalara was confirmed in the wider environment in East Anglia. These trees had no apparent connection to nurseries and suggested the presence of Chalara in Great Britain for quite some time. It is possible that this infection was caused by spores blown by the wind from continental Europe, but further investigation is ongoing.

I turn now to the current situation. As my noble friend Lord Selborne said, this morning’s situation report confirmed Chalara in 14 nursery sites, 36 sites where ash has recently been planted and 32 sites in the wider environment. Over the weekend, we have confirmed that, in addition to the cases in the wider environment in East Anglia, there are also cases in Essex and Kent.

Our scientific understanding suggests that Chalara is not currently spreading. The period of spore release is normally the summer. In the winter, the main method of spreading the disease would be movements of ash material. This, as I have said, is now banned. As ash leaves fall to the ground, there exists a risk, although it is rated as low, of the spread of the disease through the long-distance movement of leaf litter on, for example, boots and tyres. In answer to my noble friend Lord King, we have no intention of unwarranted closure of woodlands to those who wish to enjoy them, but we ask woodland visitors to ensure that they take appropriate precautions when leaving woodland.

Our understanding of Chalara continues to develop. Last Thursday, Defra Chief Scientific Adviser Professor Ian Boyd convened a group of international experts to understand better the epidemiology of Chalara fraxinea. We are dealing with considerable biological uncertainty but we are determined to make the best use of the science available to tackle this pathogen.

Lord King of Bridgwater Portrait Lord King of Bridgwater
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I will perfectly understand if the Minister cannot answer this question now, or he may like to put a letter in the Library. He made an interesting point about why this was not identified earlier. In a sense, it was. Something that had killed 90% of the ash trees in Poland was thought to be a pathogen that was already widespread and established in this country. But we did not lose that number of trees at that time. How was it that something that killed all those trees in Poland could be thought to be widely established even if it did not kill any trees in this country?

Lord De Mauley Portrait Lord De Mauley
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My Lords, I am not sure that I shall be able to answer my noble friend’s question entirely. I said that before 2010, the scientific evidence indicated that the organism responsible for Ash dieback disease was one that was already widespread and native in this country. But new scientific evidence was published in 2010 which correctly identified that that was not the pathogen and that a different pathogen caused the disease. I hope that that is helpful.

Professor Boyd concluded that: spores are mainly dispersed by wind during the summer; transportation of leaf litter should be avoided; Chalara will infect any form of ash, so exotic species in which Chalara is not pathogenic could act as vectors; latency from infection to overt disease is a matter of months; wood products would not spread the disease if they were treated appropriately using simple methods; trees probably need quite high doses of spores to be infected and may only become infected under specific conditions that are currently not understood; data from Norway suggest a spread rate of the infection front of 30 kilometres per year; once infected, ash trees cannot be treated; Chalara itself tends to kill only young trees; older trees are weakened and die from other causes and this can take years; there appears to be innate genetic resistance in some trees; and it appears that trees within forests tend to die most quickly because of secondary infection from, for example, honeydew fungus.

We are guided by the science. Our first priority is to establish the distribution of Chalara in Great Britain. This will inform our plan for tackling the pathogen. In this surveillance, we are determined to strike the right balance in the necessary trade-off between speed and thoroughness. There are two main surveillance operations under way. First, the Forestry Commission, whose staff have been working weekday and weekend, is undertaking a survey throughout Great Britain that will cover more than 2,000 10 kilometre by 10 kilometre squares in which sample trees will be examined. These survey areas are dispersed across the entire country, with an initial focus on East Anglia and the south-east, which are the areas at greatest risk of wind-borne infection from mainland Europe. To date, the Forestry Commission has inspected more than 1,000 of these squares, and we expect the survey to be substantially complete by the end of the week.

Secondly, the Food and Environment Research Agency is working hard to inspect sites that have been traced as receiving saplings from nurseries that have handled suspect consignments. In addition, we have asked a number of organisations, including the Country Land & Business Association, the Royal Forestry Society and the Royal Scottish Forestry Society, for their members’ help with surveillance over the next few days. I am enormously grateful for the positive way in which they have responded. This rapid surveillance will give us an indication of the extent of Chalara in Great Britain, equipping us to tackle the pathogen. On Wednesday, the Secretary of State and I will welcome industry representatives and stakeholders to a specially convened ash dieback summit. Ensuring that we are working with the science and with stakeholders is crucial to the effective management of the disease.

Noble Lords asked a number of questions. I will do my best to address them. The noble Lords, Lord Clark and Lord Judd, asked whether we could still burn ash firewood. We can. There is a very low risk of spreading the disease by moving firewood, but it will not be possible to move logs from affected areas in the United Kingdom where a notice has been served. One noble Lord asked whether burning trees would risk dissipating spores in the smoke. The indications are that that is very unlikely.

The noble Lord, Lord Clark, asked what the ban meant. All imports of ash-planting material are banned, as no pest-free areas exist in other countries. Movements of ash within the United Kingdom are banned pending full surveillance activity that will determine the pest-free zones.

Several noble Lords asked about Forestry Commission funding. While the Forestry Commission’s overall budget has decreased since 2010, it is not true to say that funding for plant health has decreased. The Forestry Commission’s budget for plant health research, which was £1.4 million in 2010-11, will be £2.1 million for 2014-15. Fera is responsible for plant health across the board. Its budget for plant health research was £667,000 in 2010-11 and will be £1.45 million in 2013-14. Defra has also allocated £1.3 million for each year of the current spending review period under the tree health action plan, and £800,000 for tree health research under the Living with Environmental Change programme for each year of the current spending review period. This funding will go one year beyond the current spending review period and will total £8 million over four years.

My noble friend Lady Parminter asked about the time taken for testing. In the lab, culturing an organism takes up to three weeks. Fera has adopted and developed a molecular method that reduces test time to less than four hours under ideal testing conditions. Following parallel trials of cultural and molecular tests, we are confident that the molecular procedure is robust, so it is currently our chosen diagnostic lab method.

My noble friend Lord King asked to what types of trees the Forestry Commission orders applied. Eradication action is required when the disease is found in nurseries or sites of recently planted ash. Containment notices are in place for those sites where the disease has been found in the wider environment pending the outcome of surveillance that is currently in progress.

The Government are taking further action in the full knowledge that Chalara will not, as some noble Lords mentioned, be the last pest to threaten our shores. Taking my noble friend Lord Selborne’s point, the Secretary of State has asked Professor Ian Boyd to convene a tree health and plant biosecurity expert task force to review our strategic approach to plant health as a whole, while at the European level, our negotiators are working to improve the pace of decision-making, the targeting of risk and the level of international co-operation within the EU plant health regime.

Furthermore, we are quickly bringing forward actions in our October 2011 tree health and plant biosecurity action plan—part of which, in answer to my noble friend Lady Parminter, importantly involves public engagement—to address the serious pests and pathogens not currently present in the UK.

I thank all noble Lords for their comments and suggestions, all of which I will take back. Chalara fraxinea is a serious threat to our ash population. We will continue to strive to understand and control it. We are also learning important lessons, which will help us combat future tree diseases.

House adjourned at 11.11 pm.