Posted: 15/10/2014 at 06:52
There have been lots of fungal conditions affecting tree leaves this year - probably partly to do with the mild winter we had which allowed such things to remain hanging around rather than getting killed by the frost, and then a very warm summer with damp spells provided the perfect growing conditions for such things.
If your tree had been there several years and was established my guess is that it has just shed its leaves but that the tree itself is fine and will be lovely again in the spring.
I would rake up any of the leaves that are still on the ground around it and bin or burn them, and give the tree a light mulch of organic matter (well rotted farmyard manure or compost or similar) keeping the mulch clear of the trunk but spreading it around the tree for a good 1.5m diameter. Then in February give it a feed with some Fish Blood & Bone (as directed on the pack) and that will perk it up.