Forest & Grassland Health

False Tinder Conk/Punk Ash

False tinder conk, Phellinus ingniarius.

Phellinus igniarius on birch.

Phellinus igniarius (L.) Quél.
Phellinus tremulae (Bondartsev) Bondartsev & P.N. Borisov

Host(s) in Alaska:

Alaska paper birch (Betula neoalaskana) for P. igniarius
Trembling aspen (Populus tremuloides) for P. tremulae

Habitat(s): boles, branches


Phellinus igniarius on birch.

Phellinus tremulae on aspen.

Birch decay caused by Phellinus igniarius.

The pore layer of a Phellinus igniarius conk.

Phellinus igniarius on birch.


Phellinus tremulae on aspen.

Phellinus igniarius decay on birch.

The pore layer of a Phellinus igniarius conk.

Current Status & Distribution in Alaska (2020 Update)

In 2020, we added five new records of P. tremulae for a total of 30 mapped locations in Alaska and there are two additional research grade observations reported in iNaturalist. We also recorded 24 new locations of P. igniarius, all south of the Alaska Range, for a total of 85 observations. Six research grade observations were recorded in iNaturalist. The trunk rot disease caused by both fungi is extremely widespread and common in Alaska on both birch and aspen.

Historic Activity

Phellinus tremulae is considered the most important decay pathogen of aspen species in the Northern Hemisphere and is reported to cause more volume loss than any other aspen disease. Although P. igniarius has been reported on many hardwood species elsewhere, in Alaska it is primarily observed on birch, and rarely on alder and willow species.

The conks of both P. tremulae and P. igniarius are used to make punk ash, a tobacco additive and medicine derived from burnt conks. Ethnobotanical and traditional uses of the fungus are described on this 2005 webpage by Pleninger and Volk.

Symptoms, Biology, & Impacts

Phellinus tremulae only occurs on aspen, although the conk appears identical to P. igniarius. The conks of both species are perennial, woody, and vaguely hoof shaped. They occur on live trees but can persist saprophytically for years after a tree dies. The top of most conks are dark brown to greyish-black to black and slightly glossy with many small cracks. The bottom is convex and light brown with tiny circular pores. On the inside, conks are rusty-brown with numerous white flecks.

Initial decay is yellowish to yellowish-white surrounded by a distinct dark zone line. Advanced decay is spongy or punky with numerous irregular, black zone lines. The presence of conks indicates considerable heart rot.

Survey Method

This disease is surveyed through informal ground observations and boreal forest monitoring plots.

Detection Map

Detection locations of Phellinus igniarius and Phellinus tremulae in Alaska as of 2020.  

False tinder conk (Phellinus igniarius and Phellinus tremulae) detection locations in Alaska based on plot data and informal geo-referenced observations as of 2020. Modeled aspen and birch distribution was developed by the Forest Health Technology Enterprise Team in 2011 (240m-resolution, presence based on dominant tree species by tree diameter).


Resources and Links

Hebertson, L. 2005. Guide for the Management of Aspen Heart Rot. USDA-FS Regions 1 and 4. 6pp. Available here.

Worral, J. and M. L. Fairweather. 2005. Decay and Discoloration of Aspen. USDS-FS Forest Insect and Disease Leaflet FS-R6-RO-FIDL#149. 7pp. Available here.


Content prepared by Lori Winton, PhD Forest Pathologist, Forest Health Protection,

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