Wood Decay Fungi on Living Trees

What does that mean?

Why is this topic important?
Artist's conk (Ganoderma applanatum) on European beech
                                                                        Artist's conk (Ganoderma applanatum) on European beech

Which decay fungi are common and dangerous in an urban setting? What can I do about it? Where can I get more information?

Detailed descriptions and pictures of these fungi (except Daedalea quercina) can be found in Wayne A. Sinclair, Howard H. Lyon, and Warren T. Johnson, 1987, Diseases of Trees and Shrubs (Ithaca NY: Cornell University Press).  Images are available on the web at Gary Morman's "Tree diseases that create hazards" and Flemming Larsen's "Fungi images on the net".  For other information, advice and help on this topic, call offices of your State Urban Forestry Coordinator or University Extension service, or visit urban forestry web sites.