Plants affected
Bracket fungi may appear on many different tree species. Some fungi, such as Ganoderma and Fomes species have a wide host range. Others are characteristic on certain trees e.g. Meripilus giganteus on beech and Inonotus hispidus on ash.
Symptoms
Characteristic brackets or semicircular, flattened fungal fruiting bodies
with pores or gills underneath, appear on the trunk of trees.
They are most commonly seen in cool, moist autumn weather. Some are visible all year round, such as Ganoderma species, whereas others only appear in the autumn e.g. Meripilus giganteus.
Ganoderma species are common on broadleaved trees and occasionally found on conifers, causing vigorous rots and are capable of killing trees outright. The brackets are brown with a white lower, pore-bearing surface.
Heterobasidion annosum is a vigorous species causing serious disease in conifer forests, but also affects birch and beech. It produces tough brackets with a brown, corrugated upper surface and creamy white lower surface, found on the collar or superficial roots.
Meripilus giganteus is common on beech, but also recorded on other species. The fruiting bodies are large (up to 1m/3ft in diameter) consisting of many yellow or cream tiered, fan-shaped brackets.
Infection can also cause crown thinning, small and pale leaves, late leaf flushing and early leaf shedding. Decayed branches may fall before or after the foliage dies.
Cause
Many harmless fungi live on dead wood, decaying it and eventually producing their bracket-shaped fruiting bodies. There are also a number of fungi in the genera Ganoderma, Fomes, Phellinus, Laetiporus, Meripilus, Polyporus and Inonotus, which cause decay in standing trees.
Decay fungi spread by airborne spores in autumn. The spores grow into wounds in bark, but do not penetrate undamaged bark.
Control
Avoid damage to the bark and wounding. Healthy trees are able to block the entry of fungi. Wound dressings are not generally recommended. If bracket fungi are seen on a tree, it may be in poor condition. Felling may be required to avoid injury. A professional contractor, who is properly insured, should be employed to do this. Gardeners are responsible in law for damage or injury their trees may cause.