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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.

Pests and diseases

Elm Zigzag Sawfly

Elm zigzag sawfly larvae can defoliate whole elm trees leaving them vulnerable to further attack.

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.

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.

Tree health

Report a tree pest or disease

Spotted a tree pest or disease? Report it as quickly as you can.

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

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.

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

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