Stem Decays and Stains
FIELD GUIDE TO INSECTS AND DISEASES OF ARIZONA AND NEW MEXICO FORESTS

Oak Heartrot Fungi
Inonotus dryophilus (Berk.) Murrill
Phellinus everhartii (Ellis & Galloway) A. Ames

Hosts:  Oaks

Figure 206. Figure 206. Inonotus dryophilus on Emory oak.

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. 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.

References:  30, 93