Blue stain fungi (also known as sap stain fungi) is a vague term including various

fungi A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately fr ...

that cause dark staining in sapwood. The staining is most often blue, but could also be grey or black. Because the grouping is based solely on symptomatics, it is not a

monophyletic In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic gr ...

grouping.

Included species

Depending on the author, the group can include between 100–250 species of

ascomycetes Ascomycota is a phylum of the kingdom Fungi that, together with the Basidiomycota, forms the subkingdom Dikarya. Its members are commonly known as the sac fungi or ascomycetes. It is the largest phylum of Fungi, with over 64,000 species. The defi ...

and so-called deuteromycetes. They are usually divided into three different groups: # Ascomycete fungi from the genera '' Ceratocystis'', ''

Ophiostoma ''Ophiostoma'' is a genus of fungi within the family Ophiostomataceae. It was circumscribed in 1919 by mycologists Hans Sydow and Paul Sydow. Species *'' Ophiostoma adjuncti'' *'' Ophiostoma ainoae'' *'' Ophiostoma allantosporum'' *'' Ophiost ...

'', '' Ceratocystiopsis'', '' Grosmannia''. These are usually transmitted between trees by bark beetles of the subfamily

Scolytinae A bark beetle is the common name for the subfamily of beetles Scolytinae. Previously, this was considered a distinct family (Scolytidae), but is now understood to be a specialized clade of the "true weevil" family (Curculionidae). Although the ...

. # Several

black yeast “Black yeasts”, sometimes also black fungi, dematiaceous fungi, microcolonial fungi or meristematic fungi is a diverse group of slow-growing microfungi which reproduce mostly asexually (fungi imperfecti). Only few genera reproduce by budding ...

s including '' Hormonema dematioides'', '' Aureobasidium pullulans'', ''

Rhinocladiella atrovirens ''Rhinocladiella'' is a genus of fungi in the family Herpotrichiellaceae. It has 17 species. The genus was circumscribed by Swedish botanist John Axel Nannfeldt in 1934 with '' R. atrovirens'' as the type species In zoological nomenclatur ...

'', and ''

Phialophora ''Phialophora'' is a form genus of fungus with short conidiophores, sometimes reduced to phialides; their conidia are unicellular. They may be parasites (including on humans), or saprophytic (including on apples). Genetic analysis of ''Phialo ...

'' species. # Several dark molds such as ''

Alternaria alternata ''Alternaria alternata'' is a fungus which has been recorded causing leaf spot and other diseases on over 380 host species of plant. It is an opportunistic pathogen on numerous hosts causing leaf spots, rots and blights on many plant parts. It ...

'', ''

Cladosporium sphaerospermum ''Cladosporium sphaerospermum'' is a radiotrophic fungus belonging to the genus ''Cladosporium'' and was described in 1886 by Albert Julius Otto Penzig from the decaying leaves and branches of ''Citrus''. It is a dematiaceous (darkly-pigmented) ...

'' and '' C. cladosporioides''. Importance of the symbiotic relationship between blue stain fungi and bark beetles. Symbiotic association between bark beetles and species of blue stain fungi is a well-known and studied phenomenon in the forestry pathology. Some bark beetle species like Mountain Pine Beetle (''Dendroctonus ponderosae)'' feed on phloem layer just underneath the bark of a lodgepole pines when they are developing from larval to adult stage. Mountain Pine Beetle carry the spores of at least 2 known blue stain fungi species, ''Ophiostoma clavigerum'' and ''Ophiostoma montium.'' These spores are carried on the exoskeleton of the beetles from one tree to another and aid the insects in overcoming defence mechanisms of different pine species. After the beetles initiate their attack and bore through the bark spores are released. These spores immediately start to multiply and block important conductive vessels within the tree tissues. The tree loses its ability to produce resin and to defend itself. Trade and pulp production problems associated with blue stain fungi Developing spores of the blue stain fungi are a concern in packaging materials used for shipping from Canada to Australia. Potential of introducing invasive species of fungi. According to Pulp and Paper Research Institute of Canada the wood infected with the blue stain fungus have a high proportion of fines that are not suitable for pulp production.

Economic importance

The major economic damage caused by the blue stain fungi is aesthetic because of the usually undesirable discoloration of wood. Some of the fungi have also been shown to have detrimental effects on the strength properties of infected wood. Conversely, in some cases the staining is desirable in fine wood crafting applications where it is called

spalting Spalting is any form of wood coloration caused by fungi. Although primarily found in dead trees, spalting can also occur in living trees under stress. Although spalting can cause weight loss and strength loss in the wood, the unique coloration and ...

References

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External links

Stem Decays and Stains
Phytopathology Ascomycota Deuteromycota Fungus common names