Blue stain fungi
Blue stain fungi (also known as sap stain fungi) is a vague term including various fungi 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 grouping.
- Ascomycetes fungi from the genera Ceratocystis, Ophiostoma, Ceratocystiopsis, Grosmannia. These are usually transmitted between trees by bark beetles of the subfamily Scolytinae.
- Several black yeasts including Hormonema dematioides, Aureobasidium pullulans, Rhinocladiella atrovirens, and Phialophora species.
- Several dark molds such as Alternaria alternata, Cladosporium sphaerospermum and C. cladosporioides.
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.