Xylaria guepinii

Xylaria guepinii is a species of fungus in the family Xylariaceae, known for acting as a wood-decay pathogen. It primarily colonizes dead or stressed woody tissue, but under favorable conditions, it can become an aggressive invader of living trees that have sustained physical wounds or structural damage.

The fungus affects a variety of deciduous trees, including fruit-bearing species and various ornamental shrubs. It typically enters the host through open wounds in the bark, such as those caused by improper pruning, frost cracks, or pest activity, which provide an easy pathway for mycelial growth into the cambium layer.

Symptoms of the disease are characterized by the appearance of distinct, black, club-shaped or branched stromata emerging from the bark or wood surface. These fruiting bodies are hard and woody to the touch. Internally, the wood becomes brittle and discolored, often turning pale yellow to brownish as the fungus breaks down the structural lignin and cellulose components.

The development of Xylaria guepinii is highly dependent on humidity levels. The fungus thrives in moist environments, where spores can germinate efficiently on fresh wounds. Spread is facilitated by wind, rain splashes, and insects, which transport the spores from infected timber or decaying stumps to healthy host plants.

• Implement strict sanitary pruning practices to remove infected branches.
• Apply fungicidal wound dressings or protective pastes to all major pruning cuts.
• Maintain tree vigor through proper fertilization and irrigation to improve natural defense.
• Remove and destroy severely infected wood to reduce local spore populations.
• Clean tools thoroughly with disinfectants between uses on different trees.

The economic impact of Xylaria guepinii is significant for orchards and tree nurseries, as it compromises the structural integrity of the plant. As the infection progresses, it disrupts the vascular system, leading to canopy dieback, reduced fruit yield, and ultimately, the premature death of the tree if the infection reaches the main trunk or root collar.