Symptoms/Signs: Oaks are host to many heartwood decay fungi. Two of the most
common are Inonotus dryophilus and Phellinus everhartii. The
former produces an annual fruiting body that degrades quickly following
spore dispersal, while the latter produces a perennial fruiting
body (conk) that grows a fresh sporulation layer every year.
Biology: As with most decay fungi, branch
stubs are the most common sites of heartrot infection, but entry also occurs
through trunk injuries. Fruiting bodies develop on living trees.
Figure 207. Heartrot, Phellinus everhartii, on Gambel oak.
Effects: Either species can create extensive decay in mature trees, resulting in valuable wildlife habitat
and/or creating tree failure risks in developed sites.
Similar Insects and Diseases: There are many other
fungi that decay the heartwood of living oak trees, but these are
the most common.