Oak decline

The phenomenon called oak decline has been known in the UK for nearly one hundred years. However, in the last few years there has been an alarming increase in the number of trees affected by acute oak decline – a fast-acting problem thought to be caused by bacteria.

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Oak decline. Copyright: RHS

Quick facts

Common name Oak decline, Acute oak decline, Chronic oak decline
Caused by Acute oak decline: thought to be caused by bacteria; Chronic oak decline: various pests, diseases and environmental factors.
Plants affected Pedunculate oak (Quercus robur), sessile oak (Q. petraea) and hybrids between the two
Main symptoms Acute oak decline: weeping lesions from cracks in the bark, trees can die rapidly (4-5 years); Chronic oak decline: twig and branch dieback, ‘staghead’ symptoms in crown, slow deterioration (many years)
Timing All year

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