False Tinder Conk - Field Guide to Insects and Diseases of AZ and NM Forests

Symptoms/Signs: P. tremulae produces woody conks on aspen trunks, typically at branch stubs or scars. The conks are hoof shaped, brown to black, with a rough, cracked upper surface and tan to white pore surface. The conks are usually attached to the host by a granular core of tissue that continues into the decayed branch within the trunk. P. tremulae also produces hard, blackish sterile masses of mycelium (sterile conks) at branch scars, hence the name. The yellowish white spongy decay caused by this fungus is usually confined to a central core.

Biology: Airborne spores of P. tremulae infect fresh branch stubs or wounds. The fungus decays the dead or injured area and then gains entry to the heartwood.

Effects: P. tremulae is the most common cause of aspen stem decay in the Southwest. It causes less mortality than aspen canker fungi or ganoderma root rot but can create hazard trees in recreation sites.

Similar Insects and Diseases: No other fungi with the characteristics of the fruiting body are found in aspen.

References: 30, 38, 92