The controversial role of wood decay fungi on monumental oaks in the Madonie Mountains (Sicily)

Wood decay fungi represent one of the biggest problems for the preservation of monument trees. These are organisms that greatly affect the health of the tree system (root, stem, crown) and its stability. Old oaks are subject to different attacks by white and brown rot-causing fungi. This contribution reports the presence of Pseudoinonotus dryadeus (Pers.) T. Wagner & M. Fisch. Hymenochaetaceae and Laetiporus sulphureus (Bull.) Murrill Laetiporaceae on year-old monumental Quercus pubescens s.l. in Piano Sempria (Castelbuono, Madonie, northern Sicily). P. dryadeus is a species that can attain considerable size, up to 50 cm in diameter, lignicolous, sessile, with irregularly shaped, annual basidiomes that are leathery in texture and have a yellowish tomentose sterile surface with scattered brown patches. P. dryadeus is a fearsome pathogen, agent of white rot, of tree species, especially oaks or, more rarely, spruces, and usually grows at the base of their trunks or on outcropping roots. It is an infrequent species, and its findings record single basidiomes or, at most, a few specimens developing on the same plant. L. sulphureus is a lignicolous fungus that is pathogenic as long as the plant remains alive, then acts as a saprotroph by disintegrating the now-dead plant. It generates a cubic brown wood rot, which extends into the central part of the trunk and takes several years for the plant on which it grows to die. In the initial stage of growth, it appears as an almost round, light-yellow protuberance; as it grows, shelf-like layers begin to form and overlap one another, while the surface becomes increasingly irregular and velvety, with more or less pronounced zonations. Both reported species are difficult to eradicate, and the only action to safeguard the plants is preventive with interventions aimed at the immediate care and protection of wounds generated accidentally or due to human action. The degenerative processes triggered by such wood decay fungi are counterbalanced by the recognized beneficial properties of these mushrooms, which fall under the umbrella of so-called medicinal mushrooms. Both P. dryadeus and L. sulphureus, in fact, are known for anti-cancer, antioxidant, immune-modulating, cardiovascular, anti-hypercholesterolemic, anti-inflammatory, antimicrobial, and anti-hyperglycemic properties. It is therefore necessary to safeguard monumental oaks with targeted dendrosurgery practices and at the same time safeguard the biodiversity of fungi growing on these trees through mycelium isolation and their ex situ cultivation