How to identify Ash die back (Chalara fraxinea)

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By Dorch_People | Saturday, November 10, 2012, 10:59

This is a serious disease of ash trees caused by a fungus called Chalara fraxinea, it is thought to have originated from Japan and have travelled across Europe.

The problem has been around since the early 90's. It has widely spread across eastern Europe and the fungus has caused 75% of mature ash tree casualties in forests, urban areas and young nursery trees.

Ash (Fraxinus excelsior) is the third most abundant tree in the UK, and its rapid decline will change the composition of our woodlands.

How to spot the symptoms

Fungal spores are spread by wind and land on new leaves and cause an infection.

The leaves wilt, turn brown or black and remain hung on the tree.

The infection moves into the stem causing discolouration of the stem, changing from olive green through to a brown, and also diamond shaped legions appear.

The infection moves into the trees water system so is quickly spread up and down the tree,  killing the tree by girdling it and therefore starving it of water.

If you find evidence of the disease please contact the Forestry Commission immediately.

Chalara helpline: 08459 33 55 77 (open 8am - 6pm every day)  plant.health@forestry.gsi.gov.uk

The uk/chalara">Forestry Commission explain:

• the spores are unlikely to survive for more than a few days;

• spore dispersal on the wind is possible from mainland Europe;

• trees need a high dose of spores to become infected;

• the spores are produced from infected dead leaves during the months of June to September;

• there is a low probability of dispersal on clothing or animals and birds;

• the disease will attack any species of ash;

• the disease becomes obvious in trees within months rather than years;

• wood products would not spread the disease if treated properly;

• once infected, trees can't be cured;

• not all trees die of the infection, and some are likely to have genetic resistance.

      

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