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Yellow Laminated Butt Rot of Poplars

Pholiota populnea (Pers.:Fr.) Kuyper & Tjall.-Beukers
(=Pholiota destruens (Brond.)

Basidiomycotina, Agaricales, Strophariaceae

Hosts:Pholiota populnea has been reported in B.C. on black cottonwood and Lombardy poplar.

Distribution: This fungus is widely distributed throughout the range of its hosts in B.C.

Identification: The fruiting bodies are relatively large, gilled mushrooms, often occurring in clusters, which develop on living trees or slash. When fresh, the cap is light brown and covered with white scales ( Fig. 22a ). The gills are white when immature, becoming dark brown as spores mature. The stem is white to light brown and covered with white scales; a white annulus is present. The mushrooms are abundant from midsummer to late autumn.

In the early stage the decay appears as buff to dark brown streaks in the heartwood. Later white patches form giving the wood a faint mottled appearance. In the final stage, the wood becomes uniformly yellow to tan and laminate in texture.

Microscopic Characteristics: Basidiospores cinnamon-brown, elliptical, smooth, with a germ pore, 7-9.5 x 4-5.5 µm. Chrysocystidia absent.

Damage: Although no detailed decay-volume loss studies have been conducted, P. populnea is thought to cause more loss than any other decay fungus on cottonwood.

Remarks: The fungus seems to be most damaging in living trees, only remaining active in stumps and logs for a few years following harvest.


Thomas, G. P. and D. G. Podmore. 1953. Decay in Black Cottonwood in the middle Fraser region, British Columbia. Can. J. Bot. 31: 675-692.


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P. populnea fruiting body on a cut log - CLick on this image to see a larger version

Figure 22a: P. populnea fruiting body on a cut log.