Simon Bowes examines the ongoing crisis of ash dieback in the UK

There is a belief among many who aren’t faced with working in diseased ash that there is no need for early intervention.

 I’m hearing that we have ten years, many ash will survive and recover, the mortality rate will be around 75%, diseased ash, while presenting challenges, aren’t too difficult to fell.
We’re five to six years into the crisis so more than half those ten years have gone.

Once infected all ash trees I’ve seen succumb over a reasonably brief time.
Most people on the ground are seeing almost total mortality.

Felling diseased ash presents dangers that change over the course of the infection.

Felling healthy ash requires special skills, felling ash with Chalara requires a crystal ball.

If we don’t wake up to just how dangerous dealing with infected ash is there will be fatalities, and putting off dealing with the problem now will make a bad situation worse.

YOU might have read an article in the forestry press recently that played down the crisis surrounding ash dieback. I read it with some incredulity. The author seemed to suggest – indeed did suggest – that anyone felling ash on a large scale was jumping the gun, getting carried away or maybe even cashing in on the opportunity provided by ash dieback.

I’ve currently got one ash clearfell underway. We’ve felled about 1,000 tonnes of what might well be a job of around 3,000 tonnes, although as the forester said the other day: “If we don’t start seeing a few live trees it might be an idea to carry on as long as you’re available.”

The reason for his pessimism: we have only identified three outwardly unaffected and vigorous trees in the first several hundreds we’ve felled. There’s little sign that any trees will have full leaf cover and the timber is providing moisture readings in the low teens compared with the odd birch and elm that are coming down for access, showing moisture at between 25 and 30 per cent. Most worrying is that the quality doesn’t look stunning. We had explored the idea of cutting some hurley butts and there was the possibility of export to the Far East if we could cut clean butts with little colour and no shake or splitting. Without exception, the ash we are felling is coloured and has a tell-tale stain in the centre, but we are now seeing something that looks like a watermark making a halo around the centre of the butt. This extends up the stem and on really bad trees it can be found right up to, and even beyond, the first branch notch.

I’ve driven past this tree almost every day of the last 30 years I’ve lived on this lane. It looks healthy enough, but...

I’d better give this story some context. I work in North and East Yorkshire, in the vales and on the moors of the north and on the wolds of the east. Ash is the predominant hardwood species in the area and we have some magnificent woodlands of almost pure ash. There’s always a smattering of other species and rarely have I worked in a woodland that has been specifically planted with ash. Over the last 20 years it has been common practice locally to fell areas of softwood windblow and clear the ground ready for the influx of ash. There’s never been any need to plant. Ash will come in and fill the vacuum so long as there’s light and space. It doesn’t happen on the really high, exposed sites, but in the valleys and on the stony wold land it’s a given.

...on closer inspection there is evidence of the beginning of dieback.

The major work we are undertaking has been five years in the planning (and when I say planning I mean planning with crossed fingers in the hope it wouldn’t need doing).

We began thinning the ‘Crow’ in the winter of 2008/09 as a trial. It is an area of woodland on relatively steep slopes with poor access that was felled off during WWII, with work beginning in 1940. There’s no record of any replanting and all we really know for sure is that two extremely large oaks were left unfelled, the story being they were too big to handle. The king oak has a circumference at breast height of some 23 feet or about seven metres, the smaller queen oak somewhere less at just 20 feet. A local farmer who was well into his dotage back in 2008 recalled seeing the men hauling timber out onto his father’s fields when he was a young boy. He said they were using horses to do some of the work, but two huge caterpillar tractors were used to extract the bulk of the timber.

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We thinned every inch of ground we could gain access to up until the job was as complete as we could make it at the end of the summer of 2016 and it was then that we found the first signs of the impending catastrophe that is now so evident.

Another ash showing extensive loss of foliage overgrowing a lane that carries a lot of local traffic.

We had found some wilted leaves and dead twigs on sapling ash the previous summer, but not everyone shared my concerns and the damage was put down to deer. I found what I considered to be clear evidence of the pathogen on another estate in the late winter and early spring of the following year. Later that spring, the forester on the estate at Whitby rang me sounding very concerned. This was about a month before we were due back to start felling the summer’s firewood harvest. He thought he’d found more evidence of Chalara in some young trees just along the road from the sawmill, so I sanitized my vehicle and boots and drove the 20 miles to meet up with him and take a look at his dying ash saplings.

The tree on the left is clearly stressed, producing a lot of vertical new growth, the tree on the right is already dead. This picture was taken in August 2019.

All I found were the usual dead twigs you often find on self-seeded ash plants that are struggling for light and nutrition and I put his mind at rest. It wasn’t the dreaded dieback, as it was now being called. He had another meeting to go to, so I took a tour along the many miles of estate roads and tracks and, in the best tradition of viewing woods, I did it all from the comfort of my pickup with the windows down, even where I was forcing my way along through quite invasive growth with four-wheel drive and diff locks engaged. It was in the last mile before I completed the circuit that I found it – a strip of very young ash saplings growing on a landslip. I pulled up a number of the small plants that all had the now familiar distinct green-to-brown transition on the stem. Everything above the line was a dusty chocolate brown and everything below was green and healthy. Peeling the bark back revealed the same discolouration in the cambium layer. This was Chalara and it was well established. I threw a fistful of the infected plants into the back of my pickup and with a heavy heart went back to the forester’s house where we’d arranged to meet once his meeting was finished. The next hour probably changed the direction of the management of the estate’s woodland more than anything since that mass felling during WWII. The plants I’d collected were bagged up and dispatched for confirmation, which we duly got. The estate had Chalara and now there were a series of miserable meetings with the resident land agent, the trust board and the landowner.

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We carried on thinning the ash as normal that year, but then trees on roadsides began to show serious signs of stress. Large portions of the crowns didn’t leaf properly and in the winter they began to shed large numbers of twigs during windy spells of weather. This became more evident and so the estate began to remove single trees where public use of the roads and paths was heaviest.

Ash stumps are normally a bright pink colour soon after felling, but we’ve noticed ash hardly ever ‘pink up’ where dieback is present.

Two years ago it had become clear that public safety was becoming a real issue, so I came in as the contractor removing trees from paths and roadsides in a much larger-scale felling operation. We did a new health assessment on the trees in the thinning that had been left previously and we couldn’t find a single tree that was completely healthy. In an attempt to salvage something for the future, the estate’s own staff went through the thinnings we had done and felled any really badly affected trees among those we’d left. They removed most of those we’d identified as survivors and left some that still showed promise. It was the intention that if any trees did prove resistant they would be given a chance to prove it. The landowner himself said that “it may be a forlorn hope but we must give any survivors a chance”.

Moving to the summer of 2021, all the areas identified as a risk to visitors have been dealt with and now the focus had to turn to the Crow, 130 acres that have been thinned to create a nicely spaced mixed-species woodland. In previous years we focussed almost totally on thinning the ash to make the wood more diverse. Ash is hugely dominant, but there are large numbers of different species including elm, field maple, alder, hazel, birch, sycamore, thorn and oak.

By mid June, large numbers of ash stood almost naked, showing no signs of leafing up. All the ash that will come into leaf have now done so and it isn’t a pleasant sight.

The condition of the ash we’re felling is the new concern. It’s been accepted by all involved that we can’t save the ash on the estate. Even the most optimistic among all the people involved can now see this is a fact.

Clearly defined boundary between live and dead wood on the same branch. This was taken in may 2019.

There is no cash bonanza. In fact, a very large part of the estate’s business is under real threat. It’s hard to see how the firewood business can continue, for example. Ash from the estate’s own woodlands has always been a source of income once it has been processed into firewood. I have two machines in the woodlands for around 20 weeks of the year. We fell all the firewood they need to restock the log yard ready for the following winter season and then we thin softwood to bring in income to offset the cost of the hardwood harvest. We’ve done this for many years and it works well for everyone involved. I’ve got work I can bank on through the summer and autumn running into early winter; they get the timber they need and the thinnings done that the woodland plan requires.

I’ve got a financial boost now that I can plan to cut ash all through the summer and beyond, which is undeniable. We started in April this year and we’ll carry on until the weather breaks, which will probably be mid October, but this is only short term. I had planned to carry on thinning ash for firewood for the foreseeable future, over the remaining years until I retire. In true sustainability terms, the ash on the estate should have been an ever-present resource. It’s now finite, the current thinking is maybe five years until there is no ash left. It may be that even that estimate proves optimistic because the firewood produced from the diseased ash is clearly slightly different to the live wood we’ve grown used to. We are now having to consider putting some of the timber aside for biomass. There are trees which have previously been affected by canker that have succumbed fully now that Chalara is also affecting them. The timber from these trees is dry and beginning to crumble in the centre. It doesn’t split cleanly and the fear is that it won’t burn well. I can well remember the trouble we had with elm that had been standing dead for many years. It didn’t make good firewood and ash may well go the same way. Even if this takes a number of years, the day when the remaining ash in the Crow becomes nothing more than chipwood that incurs a cost to clear can’t be far away. The first question now is: can we work the entire area while it’s still financially viable? The second is: what happens to the estate staff who’s jobs rely on the firewood business. Next: how can these woodlands be kept under management once the income stream they generate has gone? Finally: where do I place the two machines that rely on this work for five months of the year?

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Another very important consideration is how we can continue to fell large mature trees that are clearly becoming more and more challenging as time passes. The risk assessments for this work are complex and ever changing. We fell what we can with a machine. We don’t do directional felling anymore and we are having to leave some trees to be taken down in sections by the estate’s resident arborist team. None of this makes for a happy workforce and it doesn’t do anything for production, but production is not a concern. This is dangerous work and it requires a great deal of care.

The distinctive ‘watermark’ is something we’ve not seen until this summer.

On a personal level, the three of us working this site have seen the evolution of the Crow from an unmanaged wilderness into an exceptional woodland over many years. We’ve all toiled and sweated to make it what it was until the arrival of Chalara. The estate has invested heavily in tracks and roads and bridges, creating access where previously there was none. There is a hermitage and an old watermill which the public can now visit and, of course, there is the early medieval motte and bailey castle we uncovered in 2020. All this was made possible because of the firewood resource within the woodland. The public access will probably remain, but the beautiful ash woodland will be replaced by a woodland dominated by lower trees and shrubs. Although this will grow to be something special in itself, the loss of the iconic Yorkshire ash will be a bitter pill for those of us who grew up with it as the number-one tree throughout our home county.

Forestry is a long-term business. We work on rotations measured in decades and a sudden shock like this can derail years of planning and change the way huge areas of woodland can be managed. This is why I find the suggestion that people like myself, managers and landowners, can find anything that can be considered beneficial to be a major misrepresentation.

Another job we’re doing is a whole-tree clearance. I looked at it last year. It’s a landscape feature about 300 m wide and 2,500 m long, planted with a mixture back in the late 1990s with pine and larch as a nurse crop among beech, oak, cherry and thorn with a smattering of more exotic hardwoods and, of course, ash. This is all part of the restoration of the landscaping plan produced by Humphrey Repton back in the 18th century. The ash was almost entirely dead last summer and viewing it now it shows no sign of budding, just like the main blocks a mile away where we’re clearfelling.

The only financially viable option for this site is to thin the softwood for access and remove all the ash for chipping as whole trees. It’s in an area of high public use and, as it’s on the edge of the village, we can’t fell it as a conventional thinning as there will simply be too much debris left on site, especially from the ash.

The first of two sites we will move to on another estate is an ash plantation less than 20 years old. Unfortunately the tree size here makes the job almost impossible. It’s too small to chip as whole trees. That sounds difficult to understand, as surely whole-tree chipping would be the answer, but when a stem that’s as thick as your wrist will snap if you pull hard on it, then the impracticality of grabbing it with a harvesting head becomes obvious. It is too big to mulch and there is a smattering of oak that may be self-seeded in among the ash, so that particular job is a conundrum. It looks like the answer will be to fell it by hand and then forward it to the roadside to be chipped. It certainly will be a job that costs the estate money, but it’s visible from the town and last year people commented on how scruffy it looked.

In the next valley, another contractor is clearfelling a steep slope with a skyline. They are felling all the lower slopes with a harvester then taking the steeper sections off with a skyline after hand-felling it.

In common with my own site, the risk assessments (plural) are extensive and pretty comprehensive. Something we have talked about in writing these risk assessments is giving the hand-cutters the time to do the job carefully and slowly if necessary. No pressure is put on them and piecework is something consigned to history.

The challenges of felling diseased ash are well documented, although a new phenomenon has appeared on the skyline site. The drifts where they are hauling trees become littered with countless small sticks and I’m told that walking on it is near impossible. It’s like trying to stand on ball bearings apparently, so that’s something new to consider adding to the risk assessment.

I’m afraid from my point of view, and from the many contractors I speak to in my role as chair of the FCA for England, there is nothing about ash dieback we see as an ‘opportunity’. I’d rather we’d never seen ash dieback in the UK. I’d be much happier spending a few weeks cutting healthy ash for firewood each summer and not having to put my men into a situation where I spend most days worrying about whether we’ll all get home safely. I spend an inordinate amount of time trying to ensure we do everything slowly and carefully and I’m not too impressed when commentators think I’m rubbing my hands because ash dieback presents the opportunity for a bonanza.

I can say categorically it’s no bonanza. It’s a disaster.

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