Ash dieback is a fungal disease called Chalara fraxinea which causes leaf loss and crown dieback in affected Fraxinus excelsior and other species of Fraxinus trees. The disease is spread by spore dispersal from infected dead leaves carried by the wind during June to September. The disease affects trees of all ages and can lead to tree death. Young trees can be killed in one season while older trees tend to succumb after several seasons of infection. Once infected, trees cannot be cured. Ash dieback does not affect mountain ash Sorbus aucuparia trees.
Typical symptoms of ash dieback include:
Leaves: Black blotches which appear on the base and midrib of leaves
Stems: Small lens-shaped lesions or necrotic spots which appear on the bark of stems and branches which enlarge to form perennial cankers. If the bark is peeled back the wood underneath has a brownish to grey discolouration.
Trees: Affected trees show extensive dieback of shoot, twig and branches. Trees often have prolific epicormic shoots.
If you think you have spotted a tree with any of these symptoms the first thing to do is visit The Forestry Commission’s website www.forestry.gov.uk/chalara and view their symptoms video to familiarise yourself with the characteristics of Chalara dieback. If you are sure that you have identified an infected tree contact the Chalara helpline: 08459 335577 (Open 8am – 6pm Mon – Sun) or email any reported sitings to firstname.lastname@example.org.
You can also download a free app to help efforts to identify and map the Chalara disease at: www.ashtag.org
Other useful websites include The Woodland Trust www.woodlandtrust.org.uk and www.treedisease.co.uk
This lethal disease is a threat to 80 million trees in the UK which make up 30% of our deciduous woodlands. We therefore urge you to be vigilant when out and about and make yourself familiar of the symptoms.