Xenasmataceae fungi

The Xenasmataceae family comprises a group of basidiomycete fungi that, in a phytopathological context, are classified as agents of wood-decaying and corticioid diseases. These are primarily saprotrophic organisms; however, some species are capable of adopting a parasitic lifestyle on weakened woody plants and shrubs, causing destructive changes to plant tissues.

The disease is caused by members of the genus Xenasma and related taxa. Unlike obligate parasites, these fungi develop by colonizing the bark and wood, employing enzymatic mechanisms to break down lignin and cellulose. The pathogenesis type is necrotrophic, where the mycelium actively penetrates deep layers of tissue, leading to their progressive necrosis.

The disease most frequently affects perennial plantations, forest stands, and fruit crops, especially in the presence of mechanical trunk damage or frost cracks. The infection manifests as thin, waxy, or crust-like mats on the bark surface. Over time, affected areas lose turgor, the bark begins to crack, and intense decay develops underneath, resulting in the dieback of branches and reduced tree productivity.

The spread of the pathogen occurs primarily through spores (basidiospores) carried by wind or raindrops, which enter micro-cracks in the bark. Optimal conditions for Xenasmataceae development include high air humidity, moderate temperatures, and stagnant air within the canopy. High planting density and the absence of sanitary pruning significantly accelerate the infection rate of healthy specimens.

Protection measures are based on strict adherence to agrotechnical standards: it is essential to promptly remove and destroy infected plant parts and disinfect wounds using copper-based fungicides or horticultural grafting wax. Prevention involves maintaining proper orchard ventilation and applying copper-based treatments or broad-spectrum systemic fungicides during periods favorable for the spread of fungal spores.