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

Canker Rot of Oak
Inonotus andersonii (Ellis & Everh.) Cerny

Hosts: Oaks

Figure 208. Figure 208. Inonotus andersonii forms bright orange fruiting structures beneath the bark of infected trees that blacken with age.

Symptoms/Signs: Inonotus andersonii produces flat, bright yellow to yellow-brown fruiting bodies with peg-like outgrowths beneath the bark or outermost layers of wood. These fruiting bodies degrade quickly, turning dark dull brown to black, as if the wood was burned.

Biology: Branch stubs are the most common sites of infection, but entry also occurs through trunk injuries. Inonotus andersonii first invades heartwood causing a white rot, and then moves outward, killing the sapwood and cambium (hence the name, canker rot). Trees often break at these cankers.

Effects: It causes mortality when decay advances from the heartwood into the cambium, girdling infected trees.

Similar Insects and Diseases: Old fruiting bodies of I. andersonii are black and are often mistaken for fire scars.

References: 30, 93