How to Tell If a Tree Is Diseased: UK Homeowner Guide
Healthy trees add beauty, shade and value to your home — but when a tree becomes diseased, it can quickly become unsafe. As local Newmarket tree surgeons, we regularly see simple warning signs that homeowners miss until it’s too late.
Spotting problems early can prevent falling branches, costly removals, and long-term garden damage. Here’s how to identify the most common signs of tree disease in the UK.
1. Dead or Dying Branches
If branches snap easily, feel brittle, or show no leaves in spring, it’s a clear sign the tree is struggling. Deadwood is often caused by fungal infections or root issues.
Tip: If more than 20% of the canopy is dead, the tree needs professional assessment.
2. Fungal Growth Around the Base
Mushrooms, brackets or conks growing on the trunk or roots usually indicate internal decay. Fungi such as honey fungus and bracket fungi are common in UK gardens.
If you spot these, the tree may be unstable.
3. Peeling, Cracked or Sunken Bark
Bark protects the tree. When it starts to fall away, bulge, crack or develop lesions, the tree may be infected or suffering from stress.
Deep vertical cracks can make a tree structurally unsafe.
4. Leaves Turning Brown or Falling Early
Early leaf drop, yellowing, or unusual spotting often suggests pests or diseases such as:
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Chalara ash dieback
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Powdery mildew
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Bacterial infections
If only one side of the tree is affected, the problem could be in the root system.
5. Oozing Sap, Dark Stains or Cankers
Wet patches or “bleeding” areas on the bark are classic signs of infection. Cankers — sunken, dead sections of bark — usually mean the tree is fighting a losing battle against disease.
6. Unusual Insects or Borer Holes
Borer beetles and pests leave visible round or oval holes in the bark. Other signs include:
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Sawdust-like material
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Sticky residue (honeydew)
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Ant trails
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Caterpillar nests
Insects often attack weakened or diseased trees first.
7. Leaning or Cracked Ground Around the Base
If the soil has shifted, cracked or is lifting on one side, the tree may be failing at the roots.
This can make the tree a high-risk hazard, especially in windy conditions.
When to Call a Professional
If you notice any combination of the signs above, it’s safer to get the tree assessed. Diseased trees can deteriorate quickly, and what looks small from the outside may be serious internally.
Professional Tree Disease Diagnosis in Newmarket
We help homeowners across Newmarket, Suffolk and Cambridgeshire diagnose and treat tree diseases safely. Whether it’s ash dieback, root rot, or storm damage, we can provide fast, expert advice.
Call Eastern Tree & Garden Specialists: 07783 360552
Fully insured • NPTC certified • Trusted Newmarket tree surgeons
