This dieback continues from branch to branch through the stem until eventually the tree dies. This may require 1 or more years depending upon the environment and amount of stress experienced by the tree. These spores are gone within a few weeks and a grayish surface is visible. This is covered with numerous black fruiting structures. They are then blown to surrounding trees where infection occurs again.
Entry appears to be through injured surfaces on limbs or trunk.
F. Hypoxylon canker causes a dark brown discoloration of the sapwood. With age the infected wood is lighter in color and has black zones or patterns in the wood when observed in cross section. Hypoxylon canker occurs primarily on trees which are or have been in stressed conditions. Trees which have been damaged by excessive fill soil are often attacked by this organism. It is also suspected to be a fungus that can invade on oak wilt-infected trees.