Bracket fungi is the product of different fungi that causes a fruiting structure, this will also cause heartwood decay in tree. The fruiting structures appear in the seasons of spring, summer and autumn, however trees that are infected will topple at any given time.
There are many types of bracket fungi that are specific to a certain host, and normally they are not a threat to your trees. The important ones that can do heavy damage to your trees and should be a concern include:
Beech heart rots: This is caused by the bracket fungi Ganoderma applanatum. This fungi mainly affects broadleaved hosts, especially beech.
Ash Heart rots: This is caused by the bracket fungi Inonotus hispidus. This fungi mainly affects Ash, walnut, plane, elm and apple trees.
The main symptoms include:
Brackets forming on the trunk or branches
Brackets can form up to 2 ft in diameter
Falling branches due to the formation of brackets
White or brown rot within the heartwood
This causes the tree to become hollow
Unfortunately once the tree has been infected by bracket fungi there is very little you can do. removing the fruiting structures to prevent the realease of spores will only do very little.