http://www.guardian.co.uk/environment/2012/oct/28/ash-dieback-fungus-change-countryside?newsfeed=true
We lost the elm in the 70s and now the ash is set to go the same way, and the oak is under threat too.
If the symptoms include an orange rash across the bark of ash trees, I have seen it in local woodland.
Never mind, if all our woodland dies off of its own accord, it will be easer to build roads, houses and industrial estates to or heart's content without even bothering to bulldoze them.