Tree Pests and Diseases

Baroness Bakewell of Hardington Mandeville Excerpts

Thursday 13th February 2020 Lords Chamber

[Baroness Bakewell of Hardington Mandeville (LD)]

My Lords, we have had a very wide-ranging debate, in preparation for which extensive briefings were circulated on the threats posed to our native woodlands. By the time I had read my way through to the briefing from the Woodland Trust, I was completely depressed at the scale of the problem, and at the lack of action to alleviate and tackle it.

The noble Earl, Lord Devon, eloquently gave us a scenario of the effects of the disease on large estates. The number of species of true native trees is quite small; only nine, with another 10 being non-native but brought to the UK by humans over an 8,000-year period. We are all used to these species. They are not rare or exotic, but form part of the everyday landscape we see in cities, ornamental gardens and parks throughout the country: the ash, blackthorn, beech, oak, scots pine and yew, alongside the field elm, horse chestnut, larch and sycamore. We take their presence for granted, and the noble Earl, Lord Kinnoull, reminded us of the historic use of wood from these trees.

All our trees are under attack from a variety of sources. Some will show signs of attack early on, others will take four to six years before it is obvious that something is seriously wrong and the tree is in decline and dying. As the noble Lord, Lord Framlingham, said, the Government’s own risk register contains some 127 different pests and diseases which could wreak havoc in our woodlands. Easily identified pests are the grey squirrel and the muntjac deer. Both creatures have devastating effects, stripping bark, especially from immature trees. Their numbers have reached proportions where they appear to be totally out of control, but this should not deter the Government and forestry managers from taking action to control and reduce their numbers. Given the recent demise of the deer initiative, mentioned by the noble Lord, Lord Carrington, what new strategy do the Government propose to lead the wildlife management sector in England and Wales?

Other pests come in the form of insects and beetles, which lay their eggs in trees. Their larvae then feed on the wood of living trees and can eventually kill the host tree. My noble friend Lady Kramer, who is unable to be here today, has pressed me to mention the oak processionary moth. I feel that I do not need to, given the number of noble Lords who have raised it, but I promised her I would. This moth was the subject of debate in the Kew Gardens Bill and in statutory instruments last year. The moths make large nests for their caterpillars which then defoliate the tree. The caterpillar’s hairs cause breathing difficulties and skin irritations to anyone touching them. Removing nests by hand is challenging and expensive for landowners with large oak trees in open parklands and a high number of visitors. As with many introduced pests, the management cost is borne by the landowner rather than the nursery or importer who introduced the infested trees.

My noble friend Lady Kramer tells me that Richmond Park spends more than £100,000 a year eliminating moth pests to keep the public safe. This is a considerable cost which landowners of parkland must bear, to protect and preserve their ancient trees, which are held in such high regard by the public.

The third category of pest and disease is spore-based fungi, pathogens and viruses. Into this category come powdery mildew, red-band needle blight, sweet-chestnut blight and the massaria disease of plane trees. Many but not all these pests and diseases are notifiable. Nevertheless, the cumulative effect is devastating. As we have heard, the figures are stark. We have lost 60 million trees to Dutch elm disease. Up to 95% of ash trees may be lost to ash dieback, as so eloquently mentioned by the noble and right reverend Lord, Lord Harris of Pentregarth, and 13% of the UK’s total land area comprises woodland. The total monetised value of UK trees is estimated at over £4.9 billion a year and the total asset value of UK trees at over £175 billion.

The right reverend Prelate the Bishop of St Albans reminded us of the important benefits of planting new forests. Many noble Lords have mentioned the Government’s Tree Health Resilience Strategy 2018, which sets out an assessment of the importance of the UK’s trees, woods and forests. It includes benefits to health and well-being that are important to us all, opportunities for recreation and the ability to sequester carbon. This last point is crucial as we struggle with air pollution in our cities.

Despite this resilience strategy, government figures for the year to March 2019 show that tree planting in England fell 71% short of targets, which questions how committed the Government are to fulfilling their own targets. Alongside this, the Government have committed to planting 30 million trees a year to help redress the loss of mature trees. Can the Minister update us on how the Government and the sector are progressing with their objectives from May 2018?

There are a number of serious pathogens present in Europe which could make their way to the UK. We heard about the bacteria xylella fastidiosa, which could affect many native broadleaf trees and ornamental plant species. One simple precaution to lower the risk of disease introduction would be to ban the importation of the high-risk hosts, including olive, lavender and prunus species. Are the Government considering such a ban?

All contributions across the House appear to be in agreement. Clearly, the most cost-effective way to manage pests, diseases and invasive species is to prevent their introduction in the first instance by dramatically improving biosecurity at our borders. For this reason, the Woodland Trust operates a UK-sourced and grown assurance scheme which ensures that none of the trees it plants or sells are imported, as the noble Baroness, Lady Fookes, mentioned. Will the Government commit to increasing the proportion of UK and Ireland-sourced and grown trees that they plant? I was very interested in the contribution of the noble Lord, Lord Mann, on how this might be tied in with neighbourhood planning.

I turn now to some of the solutions that are available to alleviate the loss of our trees. It is not right, morally or financially, for landowners alone to pay the cost. If stock brought from nurseries proves to be infected, the nursery or supplier should pay the cost of dealing with eradicating the pests that they have passed on. During our debates last year, the Minister was adamant that all poinsettias sold in this country would come from pest-free environments and have a plant health passport attached. This was indeed the case; I checked. While a poinsettia is not an oak sapling, there are ways to transfer such a plant health passport to our precious native trees; the noble Lord, Lord Carrington, referred to that.

Globalisation has negatively impacted many of our native trees. If sufficient resources are not invested in plant health and monitoring of imported timbers, catastrophic pest and disease events may follow. This would affect the carbon sequestration of UK forests, with serious consequences. I urge the Government to tackle this issue.

The grey squirrel damage affects many tree species, reducing the economic functionality of forests to zero and reducing CO₂ sequestration. Many noble Lords have referred to the grey squirrel. Focusing on grey squirrel population control will allow a greater variety and resilience of forests and woodlands, and having better intelligence on what is being imported means that we can take steps to prevent disease arriving here.

There are technological solutions to diseases of trees, most notably the oak. Are the Government considering investing in such solutions? We know from our debates on Kew Gardens that long-term scientific research is invaluable. Investing in science and research will reap future benefits, as referred to by the noble Baroness, Lady Fookes.

Lastly, there needs to be much stronger support for tree breeding for resilience. This will enable our native species to withstand attack from the myriad pests and diseases invading our shores. I look forward to the Minister’s response.