The fungus enters the wound and causes a discoloration of the wood. Or, a fungus begins to rot roots directly with no wound required for entry. Enzymes produced by the fungus decay the wood to release nutrients for the fungus, greatly weakening the wood fibers. Wood of the internal portions of the trunk or limbs loses strength. Or, the root structure is so weakened that physical support is greatly reduced.
Limbs die giving the crown of the tree an asymmetrical shape.
Small twigs and branches may litter the ground under the tree. Larger limbs die and may fall. In the case of root rot, the entire tree may topple in a wind storm. A tree with slowed growth, branch dieback, smaller than normal leaves or needles, excessive cone or seed set, premature autumn leaf coloration, or severe winter twig kill may be exhibiting early symptoms of a disease in which one of the fungi noted below is involved. Nothing can be done for the tree once it is infected.