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Ash dieback – Chalara fraxinea

posted on October 10, 2012

UPDATE: ash dieback was confirmed today to be present in two woodlands in the East of England. These are the first confirmed cases of the fungal pathogen outside tree nurseries. 25th October 2012.

A devastating new disease affecting ash trees is now present in Britain.

Chalara fraxinea webpage

Chalara fraxinea information on the Forestry Commission website

A fungus called Chalara fraxinea (C. fraxinea) causes leaf loss and crown dieback in affected trees, and it can lead to tree death. It has devastated 90% of ash trees in Denmark, leading to concerns that the disease could have a similar impact on the British landscape as Dutch elm disease. It is likely that Defra will implement an import ban by November after calls from across the forestry sector.

Ash trees suffering from symptoms likely to be caused by C. fraxinea have  been found widely across Europe over the last 10 years. These have included forest trees, trees in urban areas such as parks and gardens, and also young trees in nurseries. Symptoms include the wilting of leaves and dieback. During the dormant winter period it can be hard to spot but black lessions on stems are tell-tale warning signs.

It was first reported in the UK in February 2012 after it was found in a consignment of infected trees sent from a nursery in the Netherlands. Over the Summer new cases were soon reported first in central England and soon after the north and east. It has been found also in four recently planted sites in Scotland.

C. fraxinea is being treated as a quarantine pest under national emergency measures, and it is important that suspected cases of the disease are reported. Visit the Forestry Commission webpage to find out more.

Read more about our work to combat tree pests and diseases at www.TreeWatch.com


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Asian Longhorn beetle outbreak in Kent

posted on April 20, 2012
Asian longhorn leaflet

Asian longhorn beetle leaflet

Forest Research and the Food & Environment Research Agency (Fera) are working to eradicate a breeding population of Asian longhorn beetle found in the Paddock Wood area of Maidstone in Kent.

The Asian longhorn beetle, native to China, poses a serious threat to a wide range of broadleaved trees. It has caused extensive damage to trees in the USA and Italy since being accidentally introduced there in recent years.

The existence of this population was confirmed first by Forest Research scientists in March.Today it was confirmed the larvae (grubs) of Asian longhorn beetle were found on 22 trees in the area and five more are considered highly likely to be infested. The infestation zone (i.e. the area within a 100m radius of each infested tree) currently covers about 8 hectares (20 acres or 80,000m2).

Asian longhorn beetles can infest a wide range of broadleaved trees and shrubs. The larvae feed undetected on the inside of the host tree or shrub, which could kill it or leave it weakened and susceptible to further pest and disease damage. Although the larvae are unlikely to emerge as adult beetles before the end of June in the UK, it is important that we remove all infested and potentially infested trees as early as possible before then. They would be a serious threat to UK woodland if they became established.

Find out more on the Forestry Commission’s webpage on the Asian Longhorn beetle. Please note that Fera must be notified of sightings of beetles or other evidence of infestation by ALB, such as exit holes in the trunk of host plants. There is a legal obligation to report the beetle or suspicious signs included in the Plant Health (England) Order 2005 and the Plant Health (Forestry) Order 2005.

Read more about our work to combat tree pests and diseases at www.TreeWatch.com


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Chestnut blight in Britain

posted on March 22, 2012

Chestnut blight, caused by the fungus Cryphonectria parasitica (C. parasitica), has been confirmed in Britain for the first time by scientists from Forest Research. The blight was found on young trees in two small orchards of European sweet chestnut (Castanea sativa) in Warwickshire and East Sussex.

The fungus 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 first originated in Eastern Asia before being introduced to North America in the late 19th Century, where it has since devastated billions of trees in the East of the country (see The American Chestnut Foundation). 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.

Identifying chestnut blight

The most obvious symptoms of 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 can also occur.

Read more about the fungus and find out how to report a possible occurence of chestnut blight on the Forestry Commission’s webpage for Chestnut Blight

Read more about our work to combat tree pests and diseases at www.TreeWatch.com

 

 

 


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