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The Forestry Commission and The Food and Environment Research Agency (Fera) are working to eradicate outbreaks of a serious new disease affecting sweet chestnut trees in southern and central England.
Chestnut blight, caused by the fungus Cryphonectria parasitica (C. parasitica), has been confirmed by Forestry Commission scientists in two small orchards of European sweet chestnut (Castanea sativa) sourced from the same nursery in France. The sites in Warwickshire and East Sussex are the first findings in Britain, although the disease has spread throughout much of Europe since it was first discovered in Italy in the 1930s.
Dr John Morgan, Head of the Forestry Commission’s Plant Health Service, said,
“It is very disappointing to discover this disease has been introduced into these orchards in England. It represents a serious threat to our sweet chestnut woodlands, so we are taking steps to eradicate it before it spreads into woodland trees or other plantations.
”We are working with colleagues in Fera to investigate the source of the two confirmed outbreaks, and will follow up other importations of sweet chestnut trees from the same source. Surveys are being carried out in nearby sweet chestnut woodlands for the disease where these are at risk from infection.”
Martin Ward, Head of the Fera Policy Programme, said:
“This is a significant finding, the first of its type in the UK. We are working with the Forestry Commission and the devolved plant health authorities in Scotland, Wales and Northern Ireland to follow up certain consignments of sweet chestnut plants which have arrived from the supplying nursery in France.
“There is no reason to believe that diseased plants have been introduced intentionally, and we are liaising with our counterparts in France to investigate this situation.
“In the meantime we would ask growers to be observant for symptoms of sweet chestnut blight on imported plants, and to report any suspicion to the appropriate authorities. We will be considering whether any changes to the EU requirements on this disease are necessary as a result of this finding, and will pursue this with the European Commission.”
The Government recently launched the Tree Health & Plant Biosecurity Action Plan to ensure that the UK's defences against tree pests and diseases are as robust as possible.
Dr David Slawson, who is leading on the stakeholder engagement elements in this plan, added,
“Once again this news demonstrates the need for all of us involved in the supply and management of trees and woodland to be constantly vigilant for signs of pests and diseases in our trees, to take the greatest possible care when importing plants from abroad, and to take preventative ‘biosecurity’ measures when visiting or working in infected woodland.”
The UK companies which received the French plants, and the growers of the affected trees, are co-operating with the plant health authorities. Where infection is suspected or has been confirmed, Plant Health Notices are served requiring uprooting of the trees and burning on site in the effort to eradicate the disease.
A guide to recognising the disease and its symptoms on sweet chestnut is in preparation, and images of the disease symptoms can be seen at the website below. Reports of suspected sightings of chestnut blight can be made to the contacts below.
Further information about the disease is available from the Forestry Commission’s website at www.forestry.gov.uk/chestnutblight.
NOTES TO EDITOR:
- C. parasitica infection is usually fatal to European sweet chestnut and its North American relative, Castanea dentata, although it appears to be less virulent in Europe than it is in America. It is believed to have originated in eastern Asia and been introduced to North America in the late 19th century, where it caused devastating losses totalling an estimated 3.5 billion trees in chestnut forests in the eastern USA. It was first identified in Europe in 1938, in Italy, and has since spread to most parts of southern Europe where sweet chestnut is grown, and to parts of northern Europe.
- Recognising the disease: The most obvious symptoms of sweet chestnut blight are wilting and die-back of tree shoots. Young trees with this infection normally die back to the root collar, and might re-sprout before becoming re-infected. Other symptoms, such as stem cankers and the presence of fruiting bodies, are described on the website.
- There are an estimated 12,000 hectares (30,000 acres) of woodland in Britain in which sweet chestnut is the predominant tree species. Most sweet chestnut woodland is located in southern Britain.
- Other tree species that can be infected include oak (Quercus) and maple (Acer) species, but the fungus currently appears to cause only minor, superficial damage to these species.
- Horse chestnut (Aesculus hippocastanum) is not related to sweet chestnut, and is not affected by chestnut blight.
- C. parasitica is listed as a quarantine organism in the UK and other parts of Europe. The UK has ‘protected zone’ status, which means that additional requirements apply. Diseased trees must be reported to the national plant health authorities, and they will prescribe measures to eradicate it where it is confirmed. Sweet chestnut plants being moved into the UK must be accompanied by plant passports.
- Reporting disease symptoms: reports of symptoms in orchards must be made to Fera’s Plant Health & Seeds Inspectorate; e-mail: email@example.com; tel: 01904 465625; web: www.fera.defra.gov.uk/plants/plantHealth/whatToDoIf.cfm.
Although there is no reason to believe that the disease has spread into woodland, reports can be made to the Forestry Commission as follows:
• for places north of the Humber-Mersey line: Tree Health Diagnostic & Advisory Service, Forest Research, Roslin, Midlothian EH25 9SY; e-mail: firstname.lastname@example.org; tel: 0131 445 2176.
• for places south of the Humber-Mersey line: Tree Health Diagnostic & Advisory Service, Forest Research, Alice Holt Lodge, Wrecclesham, Farnham, Surrey GU10 4LH; e-mail: email@example.com; tel: 01420 22255.
• Forestry Commission - Charlton Clark, 0131 314 6500;
• Fera – Alison Wilson, 01904 462380.