What is ash dieback disease?
Ash dieback is a disease that affects the common ash (Fraxinus excelsior), a tree species found throughout Scotland’s woodlands, parks, hedgerows, and roadsides.
The pathogen is a fungus, Hymenoscyphus fraxineus, which attacks the vascular system of the tree and blocks the normal movement of water and nutrients.
Branches die back progressively from the shoots downward, and the whole tree can be lost within a few years of infection.
The disease was first recorded in Poland in the early 1990s, spreading west across Europe through windborne spores and the movement of infected planting stock.
Scotland’s ash trees were first widely affected in the early 2010s, and ash trees in Scotland have been showing increasing levels of infection ever since.
How to recognise ash dieback
Leaves of ash trees affected by the disease wilt, darken, and fall before the normal autumn leaf drop. The leaf loss is usually obvious in summer while surrounding trees are still in full growth.
Look for gradual dieback starting at the tips of individual branches and working back toward the main stem.
As the disease progresses, the crown of the tree becomes increasingly sparse, with whole branches dying while others may still appear green.
Diamond-shaped lesions at the base of dead shoots are another indicator. Young ash trees often show these more clearly than mature trees, though both are vulnerable. Mature trees may hold on for several years before structural decline accelerates.
If you notice these signs in ash trees on your property, a professional tree survey is the right next step to establish how advanced the infection is and what risk the tree presents.
The scale of ash dieback in Scotland
Scotland’s 11 million ash trees account for a significant portion of the country’s native tree cover.
Ash trees exist in around 40,000 hectares of woodland in Scotland, with many more in parks, roadside plantings, and private estates.
More than one million ash trees are thought to exist in parks, public areas, and alongside roads across Scotland. The public safety implications of widespread ash dieback are substantial, and ash trees across urban and rural Scotland are affected in growing numbers each year.
Ash is one of Scotland’s most ecologically important native tree species. They provide a habitat for a wide range of plants, insects, and birds that depend on its canopy and structure.
Hundreds of lichens and mosses depend entirely on ash for their habitat, and their loss from affected woodlands would have consequences running well beyond the trees themselves.
Evidence from Europe suggests that ash dieback will affect the vast majority of mature ash trees across the UK. Scotland’s ecosystem may be approaching a crisis in the next two decades, if replanting and management do not keep pace with the losses.
What tree owners in Scotland need to do
If ash trees on your land are near a road, footpath, or public space and they’re showing signs of dieback, you can’t leave them to monitor.
As the owner of the land, the legal responsibility for a falling tree rests with you.
Trees within falling distance of roads are the ones to address first. An infected ash can decline rapidly once the disease takes hold, and a tree that fails alongside a public road is a serious incident.
Steps taken early to address infected ash trees will help to keep road users safe and will stabilise trees that might otherwise fail without warning.
The cost of managing an ash tree that’s still standing is significantly lower than dealing with one that’s already down.
Why early assessment is important
Trees have been identified as having ash dieback across many parts of Scotland, and numbers are growing every year.
Early assessment is worth doing even if the infection looks mild, because the disease progresses faster than it often appears to.
Both the Tree Council and Scottish Forestry have published guidance on managing ash dieback across Scotland.
They are worth reading if you have ash trees on your land, regardless of how many or how severe the infection looks.
Both bodies recommend taking essential steps to combat the effects of ash dieback along roadsides and in public areas early, protecting the safety of the road network and its users. Once a tree has reached structural failure, safe removal becomes significantly harder.
Otherwise if you suspect your ash trees are suffering from ash dieback, GGM Landscaping’s team of qualified tree surgeons can take a look on your behalf. We work to restore safety to areas and surrounding wildlife in our countryside, public spaces, and estate garden maintenance services.
Do all ash trees with dieback need to be felled?
No, not all trees with dieback need to be felled.
Guidance from the Tree Council recommends a risk-based approach rather than blanket felling, and not every infected ash tree needs to come down immediately.
Trees in low-risk locations, away from roads, buildings, and public areas, can be monitored over time.
Some ash trees show greater tolerance to the fungus than others, and young ash trees raised from seed in areas of lower disease pressure may remain symptom-free for several seasons.
Where a tree is heavily affected, however, the decision is usually straightforward.
The disease can lead to the decline and death of up to 50 per cent of the crown within a few growing seasons, and from that point the whole tree becomes structurally unpredictable.
Any felling work near other trees must account for the stability of surrounding trees. Removing a large ash can expose neighbouring trees to wind loads they were previously sheltered from, which increases the risk of secondary failures if not managed correctly.
There is no way to prevent the disease from spreading once it is established in a woodland or on an estate.
Early identification of the disease can provide enough time to plan and carry out safe removal before the tree reaches a dangerous condition.
Early action also reduces the volume of fungal spores produced by infected ash trees, which slows the spread of the disease to trees that may not yet show symptoms.
Ash dieback and Tree Preservation Orders (TPOs)
A Tree Preservation Order does not automatically permit felling, even when ash dieback is confirmed.
The owner of the land must still apply to the local planning authority for consent before any work can proceed.
Local councils are generally sympathetic to applications involving trees identified as having ash dieback. Working in line with the Forestry Commission and Scottish Forestry guidance on the disease strengthens any application and is usually sufficient to obtain consent.
If you are unsure whether an ash tree on your land has a TPO, check with your local council before commissioning tree safety work.
Carrying out felling without consent where an order is in place can result in enforcement action, regardless of the tree’s condition.
At GGM Landscaping, we will always check on your behalf before carrying out any tree work. This ensures complete compliance.
What to plant to replace felled ash trees
Replacing felled ash trees is not just about filling canopy gaps.
Securing more sustainable landscapes after significant ash loss means selecting suitable species that will deliver similar ecological function over the coming decades.
Native tree species are the recommended choice for ash woodland replacement.
Rowan, downy birch, hazel, field maple, and wild cherry all establish well in Scottish conditions and support the insects, lichens, and birds that the ash tree cover previously sustained.
Ash trees exist in around 40,000 hectares of woodland in Scotland, and replacing even a fraction of that requires sustained effort. Scotland over the next two decades faces a significant challenge in maintaining tree cover and the biodiversity that depends on it.
We take replacement seriously at GGM Landscaping, helping secure Scotland’s biodiversity future.
How GGM can help with ash dieback on your land
We carry out tree surveys and risk assessments for ash dieback across private properties, commercial grounds, and estates throughout Scotland.
A survey maps the location and condition of your ash trees, identifies those within falling distance of roads or structures, and produces a prioritised plan for how to address them. We also identify trees that can be safely retained and monitored rather than felled.
For trees requiring removal, our tree removal team handles the full process from assessment through felling, chipping, and site clearance. Where a Tree Preservation Order applies, we prepare the application documentation as part of the service.
For land where replanting is required after felling, our team can design a native planting scheme to restore tree cover and habitat to the affected area.
To arrange a survey of ash trees on your property, get in touch with our friendly team and we’ll come out to assess the site with you.