Annual and perennial identify whether the fruiting of a decay fungus produces spores for a single growing season or part of a growing season (annual), or whether the fungus continues to produce a new pore layer and spores from the same fruiting structure over several or more years (perennial). The terms do not refer to the progression of decay of wood in the tree which continues whether the fungus is producing a fruiting structure or not on the tree.
Annual wood decay fungi develop fruiting bodies that only produce spores for one growing season or a small portion of a growing season. These fungi generally either produce mushrooms (Photographs 1 and 2), or conks that are tough and leathery (Photographs 3 ) but not woody. The mushrooms may have gills, pores or a smooth spore producing layer, while the tough and leathery fungi usually have a poroid spore producing layer (see hymenium for these descriptions).
Some annual fungi may linger on infected trees from fruiting earlier in the season or the fruiting can be found the growing season the year after they initially produced spores (Photograph 3 and 4) . In some cases they may be found still attached to the tree, or at the base of the tree after they have fallen off. Annual fruiting fungi may only fruit in certain years and therefore may or may not fruit in consecutive years on the same tree.
A small number of the wood decay fungi with annual fruiting structures produce black, crusty, fungal material on the bark or decayed wood of infected trees (Photo 5). These fungi may also produce a secondary spore stage on their surface early in the season that covers the surface with a white or gray colored spore layer (Photograph 6).
Indications the mushroom or conk is an annual fruiting structure are:
- Mushroom, or soft and fleshy fruiting, on wood or attached to roots on the soil next to or near the tree
- Dried mushrooms that have discolored brown, black or are discolored and moldy
- Presence of similar sized and off-color conks adjacent to fresh fruiting during the growing season
- Absence of more than a single pore layer when the conk is cut in half
Wood decay fungi with perennial fruiting bodies produce spores in more than one season from the same conk. The conks of these fungi are woody and are usually difficult to remove from the wood they are attached to. Virtually all are attached to the trunk of the main trunk of the tree or larger diameter scaffold branches. On rarer occasion they may be found attached to large diameter buttress roots. They seldom if ever are found fruiting from buried roots next to or at distances away from the base of the tree.
Indications the conk is a perennial fruiting structure are:
- Woody, hoof-shaped or flattened conks attached to the trunk or large scaffold branches (Photographs 7 and 8).
- Difficult to remove from the tree without a mallet or considerable effort
- Typically thick (2-5+ inches) and increasing in thickness and size with age as evidenced by
- Evidence of multiple pore layers when the conk is broken in half (Photograph 9).