First discovered in Europe in the 1930s but only recently discovered in the UK in Warwickshire and East Sussex, both sites had trees sourced form the same location, subsequently another 7 locations were found within the Uk with smaller number of trees. When Sweet chestnut blight was accidentally introduced from Asia to Eastern USA in the first half of the 20th century, an estimated 3.5 billion Sweet Chestnut (Castanea sativa) were killed by the disease.
The ascomycete fungus Cryphonectria parasitica, attacks the bark.
Dead bark becomes visible as a sunken canker.
Orange spores may be visible in bark cracks, these may exude long orange/yellow tendrils of spores
Stem girdling can occur quite quickly, leaves above the girdling canker will turn brown and wilt but stay on the tree. Leaves below will appear healthy.
A pale brown mycelium may be present in the inner bark.
Where chestnut blight was found within the UK the forestry commission served notice for all the sweet chestnuts to be uprooted and burnt, surveys were also carried out within a 3km radius. Sweet chestnut are grown commercially both in Europe and the Uk so the disease could have an economic impact as well as an environmental one.
In order to import Sweet chestnut you must have a plant passport, all imports must be notified to the UK plant health authorities so inspections can be carried out.
For more information on Sweet Chestnut blight please visit Forestry.gov