Shaggy Bracket Fungus

Ash tree in Oliver Tynan's garden
Byfield, 10 September, 2013

My friend Oliver Tynan has a lovely garden. One of the most attractive features is a small pool, permanently fed by a spring. It is overhung by a very large ash tree which, when I looked at it a few days ago, presented a quite remarkable sight, for a bracket fungus which has attacked it was shedding rust coloured spores in vast numbers. Millions (billions?) of them were staining the trunk of the tree and surrounding vegetation. Perhaps normally these are quickly washed away or dispersed on the wind, but the weather has been very dry recently and the tree is in a sheltered spot, subject only to light breezes.

The fungus involved appears to be Shaggy Bracket, Inonotus hispidus, a widespread and fairly common species whose target is normally ash but will occasionally attack oak and other broad-leaf trees. 
A closer view shows how nearby ivy leaves  have been dusted with spores, as had herbaceous plants and grasses nearby.

A closer view of the tree showing the concentric
rings on the fungus which help to identify it.

Like most (all?) bracket fungi, Inonotus hispidus is a pathogen and so will lead to the death of the tree. It is an unfortunate fact that local authorities and land owners generally feel obliged to cut down these diseased trees, and where a falling branch could be a hazard this is understandable. But if the tree can be allowed to decay and fall it will be of enormous value to a great range of creatures for whom the timber is a vital resource.

Incidentally Chris and I were on the bus returning from Banbury yesterday when substantial branch of rotten wood fell on to the bus with a startling thump. The driver was forced to pull in to the roadside and check his vehicle. Nothing vital had been damaged but the roof had a significant dent. Had the branch fallen on to a small vehicle it would have been serious, almost certainly resulting in injuries.