Auricularia

Auricularia is a genus of basidiomycete fungi that, in agronomic and arboricultural contexts, is often identified as a wood-decaying pathogen. While some species are edible and ecologically significant, their colonization of live or weakened orchard trees indicates an ongoing infection process that compromises the structural integrity of the wood.

The causative agents are xylem-feeding fungi that gain access to the tree's internal tissues through bark injuries, pruning cuts, or frost cracks. The infection progresses as the mycelium breaks down structural polymers such as lignin and cellulose, leading to a condition commonly identified as white rot within the tree's vascular system.

The host range of this fungus primarily includes various deciduous trees, with a particular affinity for fruit trees like apple, pear, and plum species. The disease typically exploits trees that are already suffering from environmental stress, nutrient deficiencies, or improper maintenance, which weaken the natural resistance of the tree.

The most distinct symptoms include the presence of ear-shaped fungal fruiting bodies appearing on the bark of the trunk or major branches during periods of high humidity. Internally, the wood loses its density, becomes brittle, and displays significant discoloration, which eventually leads to the collapse of the affected limb or the entire tree.

Disease development is heavily influenced by prolonged periods of moisture and the presence of exposed woody tissue. Management strategies must focus on preventative measures: immediate sanitization of pruning tools, protective treatment of all mechanical wounds with pruning sealants, and maintaining overall tree vigor through appropriate fertilization and water management.