Dryad’s Saddle (Polyporus squamosus)
Fruiting bodies: April – August
Area of infection: trunk
Wood decomposition: white rot
Comment: Wound parasite. It is not uncommon for the diameter of the fruiting bodies to be 40 cm.
Effect: Enters through wounds in the trunk and decomposes the heartwood.
Recommendation: Tree should be evaluated. More photos.
  
  
Photos Dryad’s Saddle