Ash dieback and other diseases don't always make a tree look obviously dead. Here's what to look for, and why disease changes the urgency.
Not every tree that needs removing looks dead. Disease often takes hold gradually, and a tree can be structurally unsound well before it looks obviously unwell from the ground. Ash dieback is the one most Chesterfield gardens are likely to encounter, since ash is a common garden and boundary tree across Derbyshire, but it's worth knowing the general signs beyond that one disease too.
Look for dark, diamond-shaped lesions on the bark, usually at the base of a side shoot that's already died back, along with blackened, wilting leaves earlier in the season than you'd expect from normal autumn colour. Dieback typically starts at the crown and works down, and a stressed tree often responds by pushing out bushy epicormic growth lower down the trunk, which can look like health from a distance but is actually a sign the tree is struggling. Once a mature ash is significantly affected, the wood tends to become brittle and unpredictable faster than with most other hardwood diseases, which is why arborists generally treat a badly affected ash near a path, drive or seating area as a higher priority than the same stage of disease in a less exposed species.
Outside the growing season a healthy deciduous tree can look just as bare as a dead one, so a scratch test on a small area of bark is the simplest check: live wood is green and slightly moist just under the surface, dead wood is dry and brown all the way through. Checking two or three spots on different branches gives a more reliable picture than one, since a tree can be dead in one limb and alive in the rest.
A tree that's simply old but structurally sound can often be monitored for years. A tree with an active disease affecting its wood strength is a different calculation, since the failure risk can increase faster than the visible symptoms suggest, and a branch or the whole crown can come down with less warning than a straightforwardly dead tree would give. This is the reasoning behind treating disease as a safety question first and a garden-tidiness question second, particularly for any tree standing near a house, a boundary, or somewhere people regularly walk or park.
Anyone who owns land has a general duty of care to manage foreseeable risks from things on it, trees included, and a diseased or structurally compromised tree that later fails and causes damage or injury can expose the owner to a negligence claim if the risk was reasonably foreseeable and nothing was done about it. This doesn't mean panicking over every unwell-looking tree, but it does mean a tree with genuine structural signs near a target, a path, a road, a neighbouring garden, is worth acting on rather than leaving for another season. If a storm gets to it first, our storm-damaged tree checklist covers what to do in the immediate aftermath.
A Tree Preservation Order still applies to a diseased or dying tree, and removing it without consent is still an offence unless the narrow dead-or-dangerous exemption genuinely applies, covered in more detail in our guide to Tree Preservation Orders. A tree that's merely diseased but not yet posing an immediate danger generally still needs a normal consent application, not the emergency exemption, so it's worth checking the register rather than assuming disease alone is enough justification.
Last reviewed 2026-07-21.
Look for diamond-shaped dark lesions on the bark, blackened wilting leaves earlier than normal seasonal colour change, and dieback starting at the top of the crown and working down. Bushy regrowth lower on the trunk is often a sign the tree is stressed and compensating, not a sign of health.
Not automatically, but it needs assessing rather than assuming either way. Location matters as much as condition: a dead tree well away from anything it could hit is a lower priority than a smaller dead branch directly over a path, drive or seating area.
Generally yes, in the same way as any other TPO tree. There's a narrow exemption for trees that are genuinely dangerous, not just diseased, and using it for a tree that's merely unwell rather than an immediate risk doesn't hold up if challenged.
What a TPO covers, how to check if your tree has one, and what happens if you cut a protected tree without consent.
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