Phaeolus schweinitzii

Phaeolus schweinitzii forms large polypores and is the cause of Schweinitzii root and butt rot.  It slowly weakens trees by rotting the heart and butt wood, and in advanced decay stages it creates a brown cubicle butt rot that leaves the host susceptible to wind and other stresses.

Common names: Dyer’s polypore, velvet-top fungus, cowpie fungus.

Description:  A fungus that produces large fruiting bodies near the base of its hosts, typically the bottom 3 meters of stems.      

Identification: Because the rot produced by this fungus is similar to those produced by other fungi, the fruiting body is needed to make a sure diagnosis.  The large fruiting bodies that this fungus produces are a sure sign of this pathogen.  Also known as the velvet top fungus, this conk gets its common name from the velvety texture of its cap.

Hosts:  Has a preference for Douglas-fir, but can also be found on other conifers.  According to the Field Guide to the Common Diseases and Insect Pests of Oregon and Washington Conifers, it is also commonly found on “western larch, Engelmann spruce, Sitka spruce, lodgepole pine, ponderosa pine, Jeffrey pine, western white pine, and sugar pine.  It is occasionally found on western redcedar, western hemlock, mountain hemlock, grand fir, white fir, Pacific silver fir, noble fir, Shasta red fir and subalpine fir”.

Distribution:  Common throughout western Washington forests.


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