Fomitiporia

Fomitiporia is a genus of wood-decay fungi responsible for severe timber and perennial plant diseases, most notably known as a primary causal agent of Esca, a devastating grapevine trunk disease. These fungi function as white rot pathogens, systematically breaking down the plant's structural components, specifically lignin and cellulose.

The disease affects a wide range of woody plants, including grapevines, fruit trees, and various deciduous species. The pathogen enters the vascular system primarily through pruning wounds, frost cracks, or other mechanical damages. Once established, the mycelium colonizes the internal wood, leading to necrosis and the systemic spread of fungal toxins within the host plant.

Symptoms are often internal, making early detection difficult. In grapevines, infection manifests as leaf chlorosis and necrosis, often called tiger-striping, and can lead to sudden apoplexy or vine collapse during hot weather. On larger trees, the presence of persistent, hard perennial conks on the bark is a definitive visual indicator of long-standing internal decay.

Favorable conditions for fungal propagation include high humidity and the availability of large, untreated wood surfaces. Infection is predominantly spread by airborne basidiospores during wet weather conditions, as well as mechanically by pruning tools that have not been adequately sterilized between different plants.

Management focuses strictly on prevention because curative treatments are largely ineffective for internal wood rot. Effective strategies include:

• Implementing strict sanitation protocols for pruning tools.
• Applying protective pruning sealants immediately after cuts.
• Removing and destroying infected vine wood to reduce the local inoculum density.