[Alisdair]

The UK plant health authorities are currently consulting about a serious new disease affecting ash trees (Fraxinus) of many species. It is a fungal disease, now called Chalara fraxinea, and appears to be spreading rapidly through Europe (though has not yet become established in the UK).
Though the disease has been most widely spread in north western Europe and Poland, it has recently been reported in southern Europe too (in France and Italy).
Symptoms to look out for are lesions and cankers in the bark, with discolouration of the underlying sapwood. When these lesions girdle parts of the tree, it dies back - leaves, shoots, twigs, branches, then the whole tree. There may also be necrotic patches on leaflets, leaf veins and stems.
Have any forum members come across this new killer yet?
You can see the UK risk assessment here.

[MikeHardman]

Ooo - not goood.

Not to be confused  with cramp balls or King Alfred’s cakes (Daldinia concentrica), which are not uncommonly seen on ash trees -
http://www.woodlands.co.uk/blog/flora-and-fauna/king-alfreds-cake/

[JTh]

This disease was first described in Norway in 2008, and it has now been spread to large parts of southern Norway, especially along the coast.

The ash tree plays an import role in the old Norse mythology, the giant ash - Yggdrasill - spreads its limbs over the entire mankind, and it is considered very holy. The ash has three roots, each of them sucking water from its own spring.
The first spring- Hvergelmir - is found in the ice cold North; next to the spring, the serpent Níðhoggr is ceaselessly gnawing at the roots of the ash. The second spring - Mímisbrunnr - is the source of wisdom and is guarded by Mí¬mir. The third spring - Urðarbrunnr - is guard¬ed by three women, the Norns, which mete out man's thread of life.

It would be very sad if the ash should disappear here.

[Alisdair]

Thanks for that, Jorun! The UK authorities are at least considering following Norway's rules, about establishing quarantine zones, transplanting restrictions, and sterilisation of any pruning and mowing equipment moving from infected areas to disease-free areas. I hope they will indeed follow Norway's lead if the disease takes a hold here too, but at the moment the best hope here seems to be to screen imported material carefully.

[John]

I have not seen it yet in south west London but feel helpless to do anything about it and assume they will be devastated. One report suggested that although it has been brought in on commercial stock from the continent it may have been in Kent for a couple of years from spores that have blown in.