Ash dieback disease: a deep-rooted problem

Ash dieback has now been confirmed at seven sites across Scotland, reports Julia Horton, with its spread posing a real threat to the landscape, ecosystem and the timber trade.

IT is a long time since the Caledonian Forest covered the Scottish countryside and provided a thriving diverse natural habitat. Only remnants of the ancient forest still exist after vast swaths were burnt for fuel, cleared for farming or over-grazed by sheep and deer.

In the 1970s a new threat to Scotland, Dutch Elm Disease, wiped out millions of trees, changing the landscape again to devastating effect. Yesterday, ministers and experts held an emergency summit in London to debate what many have been calling “the new Dutch Elm Disease”.

Cases of Chalara ash dieback have now been confirmed at seven sites across Scotland and 115 sites across England and Wales. At first glance the numbers sound small. Only 17 per cent of Scotland is covered by woodland; of that just 4 per cent consists of native trees, of which around 15 per cent is ash. But while the proportions don’t appear that significant, ash is still the third most common broadleaf tree in the country, and actual numbers are still huge, with millions of ash trees under threat across Scotland.

While the main focus of yesterday’s meeting was ash dieback, experts have long warned that the devastating disease is just one of many diseases and pests threatening Scotland’s native trees and woods. Their rise is directly related to the rocketing global trade in timber, which has evolved to become a multimillion-pound industry in Scotland.

As the ash dieback crisis has grown, many have criticised the UK government for failing to ban imports of ash until last week, years after ministers were warned of the danger that imported plants posed. While the new taskforce set out priorities yesterday, experts in Scotland warn that without swift action on all diseases, trade here could be decimated, and the nation’s woodlands wiped out entirely.

At Alba nursery in East Lothian, around 100,000 ash are set to be destroyed as a result of the outbreak, losing the business £40,000 this year alone. Two years ago an outbreak of Phytophthora ramorum in larch forced Alba to destroy 80,000 trees, and there is growing concern about the threat posed by Scots pine red band needle blight, now known as Dothistroma.

Grant Murray, sales director at Alba Nursery in East Lothian and spokesman for UK forest nurseries says: “Over half our nursery is Scots Pine. If we lose the Scots Pine we would be out of business within a year. At least half of each nursery’s stock [in Scotland] is trees that are currently under threat from pests and diseases. If they don’t get hold of these pests and diseases, all the nurseries will go out of business. It is really important to do short-term stuff, but they should have been doing this years ago. A lot of the focus is on ash now, but actually it needs to be on plant health in general and the risk of all these diseases.”

Given that the diseases appear to have all been brought in through imports, the idea of growing every species in the country instead of importing would, if possible, appear to be sensible. Alba is one of few nurseries to grow all its trees, without importing any 
species.

Murray believes more money should be invested to help end the need to import any trees to the UK: “We can grow all the trees in the UK that we want. People thought it was impossible but it isn’t.”

The Woodland Trust Scotland is among those calling for action on all diseases. Carol Evans, director of the organisation, says: “The one that worries me most at the moment kills juniper, and Dothistroma needle blight which kills Scots Pine, another iconic species in Scotland. Larch is being killed by Phytophthora ramorum, and although larch is not a native species it has become a part of the landscape which everyone recognises, especially at this time of year when they are turning colour.

“I don’t think we will ever be completely free of all pests and we don’t want to be rid of all of them, as some are useful, but others like ash dieback unfortunately kill trees. We need the government to develop clear guidance for landowners on the best way to tackle the pests and diseases already present. Tighter biosecurity measures are also needed to stop new threats coming into the country. We would ask people visiting woods this autumn to keep to main paths, comply with any notices, and show tree diseases a clean pair of heels by following basic biosecurity measures, including washing footwear, bike and car tyres before visiting any other sites.”

With thousands of trees being felled and the prospect of potential bans on movements around the countryside, the situation has similarities to efforts to contain foot and mouth disease ten years ago. The National Trust for Scotland (NTS) is urging politicians and officials to give diseases like Phytophthora ramorum, Dothistroma and ash dieback the “strategic and practical attention they deserve if they are to avoid a national crisis beyond the scale of that caused by the 2001 outbreak of foot and mouth disease”.

Terry Levinthal, NTS’s director of conservation services and projects, says: “Although we commend the most recent efforts of the Scottish and UK governments, and Forestry Commission Scotland and Scottish Nautral Heritage in particular, it is true to say that the pathogens now sweeping across the country are only now receiving the right degree of attention. Plant welfare has not received the same level of interest as animal welfare, despite the potential ecological impact it could have on our treasured landscapes.

“This has been extremely frustrating as we have been raising this issue since the mid-2000s and asking for co-ordinated action.”

Calling for government funding to help foot the bill for efforts to combat ash dieback, he says: “It is the Trust’s position that letting the costs of managing plant health fall to private individuals or charitable organisations is unreasonable and untenable. We therefore ask the governments of the UK to recognise this, and put adequate resources in place to assist those of us addressing such outbreaks.”

The Forestry Commission Scotland (FCS) is working with the Scottish Government on the response north of the Border and will be embarking on more detailed surveys of sites identified this week as being infected.

It has increased spending on “rapid response to such outbreaks, from around £50,000 to more than half a million in the past three years.

Next week a summit will be held in Scotland to update forestry managers on the current level of ash dieback, and what can be done to limit its spread.

Hugh Clayden, tree health policy officer at FCS, says: “The most important things right now are increasing surveillance, which we are doing, and awareness, so people know what they have got and what can be done about it.”

Advice to managers is likely to include thinning trees, to reduce the risk of spreading infections, and pesticides have not been ruled out as a potential way of limiting disease in future.

Ash is one of the toughest trees in the world and its timber has long been used for a wide range of purposes from furniture to tool handles and hockey sticks.

It is a vital part of Scotland’s ecosytem, as Dr Maggie Keegan, head of policy at Scottish Wildlife Trust, explains: “The ash tree is a unique tree in woodland ecosystems. The way its leaves are and the lateness of them opening and dying means there is a lot of light reaching the undergrowth. Ash have an alkaline bark which attracts particular lichens and mosses that in turn attract insects, which attract birds. Some of our rare species will become rarer still if we lose the ash.”

Back at Alba nursery, Murray speaks for many as he says: “It would be unforgiveable for future generations to look back and ask why all our woodlands are dead, all to save a few pence.”