Also commonly called conifer parchment, white rot fungus (Phlebiopsis gigantea) is found on the bark and dead wood of conifers throughout North America. A cosmopolitan species, white rot fungus also grows in Europe and Asia. It plays an integral role in the breakdown of wood.
The fruiting body of this fungus forms crust-like sheets with an unspecialized spore-producing surface. i.e. lacking spines, pores or tubes. The mushroom is spreading and colorless to white to pinkish buff. The fertile surface is pale pink to olive buff. When wet white rot fungus is swollen, when dry it is parchment-like, sometimes becoming free and curling away from the wood.
In addition to its role in degrading dead conifers, white rot fungus is used as a biological control for annosum root rot (Heterobasidion annosum) in conifer plantations. H. annosum is a disease-carrying fungus that causes root rot under the ground in conifers and above the ground causes the tree to seriously decline and become more susceptible to bark beetles. The hyphae of white rot fungus antagonize the hyphae of H. annosum upon contact, causing protoplasm disorganization and affecting membrane integrity. In conifer plantations, stumps are innoculated with white rot fungus or saw blades are painted with a solution of spores, preventing colonization by annosum root rot. Fascinating!!
Other scientific names for white rot fungus include Phlebia gigantea and Peniophora gigantea.
This white rot infected Douglas fir was photographed along the Falls Loop at Burney Falls State Park CA.