Phaeoacremonium

Phaeoacremonium is a genus of ascomycetous fungi within the family Togniniaceae that acts as a serious plant pathogen. These fungi are globally recognized as the causal agents of grapevine trunk diseases, most notably esca, Petri disease, and black measles. They function as systemic pathogens that colonize the xylem vessels of woody plants, leading to severe vascular obstruction.

While the pathogen is best known for affecting grapevines, it also has a wide host range including stone fruits, olives, kiwi, and various nut-bearing trees. The fungus enters the plant tissues primarily through pruning wounds, frost cracks, or other mechanical injuries. Once inside, the fungus spreads through the woody tissues, causing internal necrosis, wood discoloration, and significantly reducing the lifespan and productivity of the plant.

The biology and infection cycle are characterized by the production of conidia that are disseminated through rain splashes and wind currents. These spores infect fresh pruning wounds, making the timing of canopy management and maintenance operations critical. The fungus survives as mycelium within the colonized wood, meaning it can persist in infected plant debris or dead branches for many years, serving as an inoculum source.

The harmful effects of Phaeoacremonium are devastating for viticulture, as the disease is progressive and often results in sudden apoplexy or slow decline of the vine. Visible symptoms include interveinal chlorosis, foliar necrosis, and stunted shoot growth. Because the pathogen colonizes the deep internal vascular system, it is difficult to eradicate once a tree or vine has become permanently established with the fungus.

Effective control requires strict adherence to sanitary practices in the field.

• Sanitize pruning equipment thoroughly to prevent cross-contamination between plants.
• Apply fungicidal wound dressings or specialized protective pastes immediately after pruning.
• Source only certified disease-free propagation material for new plantings.
• Systematically remove and destroy highly symptomatic or dead plant parts to reduce the spore load.