Figure 202. Fomitopsis pinicola on dead Douglas-fir.
Symptoms/Signs:Fomitopsis pinicola forms perennial conks that are corky
and shelflike. Its characteristic feature is a red-brown band near
the white to cream colored edge. These fruiting bodies form on dead
trees and logging slash and not on infected living trees. The decay
is a brown cubical rot with shrinkage cracks in which prominent
white sheets of mycelium develop.
Biology: This fungus enters living trees
with airborne spores colonizing and infecting through wounds and
broken tops. It may be introduced into dying or dead trees by insects,
as it has been isolated from Douglas-fir bark beetles captured both
in flight and from egg galleries.
Effects:Fomitopsis pinicola is one of
the most important brown rot pathogens of old-growth western conifers,
but it acts slowly and is not considered a major decay pathogen
of second-growth forests. However, it is an important component
of the coniferous forest ecosystem because it decays dead trees
and logging slash and leaves a lignin-rich residue that is very
stable and is a major component of the organic matter on the forest
floor and in the upper layers of soil. This residue enhances water
holding and cation exchange capacities of soil and is a favorable
habitat for the development of ectomycorrhizae and for nitrogen-fixing
bacteria.
Similar Insects and Diseases: Brown rot
caused by F. pinicola is difficult to distinguish from
that caused by Phaeolus schweinitizii, a butt rot of Douglas-fir.
Since P. schweinitzii is a root and butt rot pathogen,
it is found in the lower 3 meters of the trunk and in the roots,
and it fruits from the roots out through the soil of live trees.
Fomitopsis pinicola only fruits on dead wood material so is frequently
observed on stumps.