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Pests and diseases
Pests and diseases by tree species
To make it easier for you to spot tree pests and diseases, we have listed our 22 priorties by main host tree species.
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Pests and diseases
Asian Longhorn Beetle
Native to Eastern China, Japan and Korea, this beetle can infest a wide variety of trees with beetles emerging from spring onwards.
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Pests and diseases
Elm Zigzag Sawfly
Elm zigzag sawfly larvae can defoliate whole elm trees leaving them vulnerable to further attack.
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Pests and diseases
Great Spruce Bark Beetle
Accidentally introduced to the UK in 1982, the great spruce bark beetle damages spruce trees by tunneling into their bark.
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Pests and diseases
Red-necked Longhorn Beetle
The red-necked longhorn beetle larvae tunnel and feed under the bark of trees in the Prunus genus, such as cherries and plums.
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Tree health
Report a tree pest or disease
Spotted a tree pest or disease? Report it as quickly as you can.
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Blog
The science behind Observatree
As part of the ongoing ten-year celebrations, Peter Crow, Observatree's project manager, looks at the power of combining citizens and science.
Peter Crow • 25 Oct 2023
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Pests and diseases
Sweet Chestnut Blight
Sweet chestnut blight is a fungus that grows beneath the bark of sweet chestnut trees causing cankers that can girdle the tree.
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Blog
Canker Stain of Plane Trees: A Silent Legacy of World War II
Canker stain of plane (caused by the fungus Ceratocystis platani) may be a rather obscure pathogen to most, but its story intertwines with one of history’s most turbulent chapters: World War II.
Duncan Allen • 29 Apr 2025
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Blog
Host of the month - Beech
Matt Parratt highlights Beech (Fagus sylvatica), its associated Beech leaf disease (BLD) and how to spot it.
Matt Parratt • 19 Jun 2025