Phaeoacremonium amygdalinum

Phaeoacremonium amygdalinum is a species of fungi within the Togniniaceae family, recognized as a significant pathogen responsible for various wood-decay diseases in perennial crops. This fungus acts as a vascular pathogen, colonizing the plant's xylem and interfering with the effective translocation of water and essential nutrients.

The primary hosts of this fungus include grapevines (Vitis vinifera) and various stone fruit trees, such as almonds. The pathogen is known for its ability to persist within the woody structures, causing progressive decline symptoms that can eventually lead to the complete death of the plant if left unmanaged.

Symptoms of an infection typically include restricted shoot growth, chlorotic foliage, and the gradual dieback of canes or entire branches. A hallmark diagnostic feature is visible upon cross-sectioning affected wood, which reveals darkened zones, brown streaking, or necrotic lesions resulting from the fungal activity and the plant's necrotic defense response.

The infection cycle is primarily driven by spore dispersal via wind and rain splashing. Spores infiltrate the host plant through pruning wounds, frost cracks, or other mechanical injuries. Favorable conditions for colonization include moderate temperatures and high humidity, which facilitate spore germination and fungal mycelium expansion within the xylem tissues.

Effective management and prevention strategies include:

• Pruning during dry weather conditions to minimize the risk of infection.
• Strict sanitation protocols, including the disinfection of pruning tools between vines.
• Applying protective wound sealants to large pruning cuts to create a physical barrier.
• Removing and destroying infected wood to reduce the local inoculum density.
• Ensuring the use of certified pathogen-free nursery stock to prevent farm introduction.

The economic impact of Phaeoacremonium amygdalinum is substantial due to its latent nature, which often hides the infection until significant tissue damage has occurred. Because there are no curative fungicides for systemic wood infections, the focus remains strictly on cultural management and preventative measures to maintain the long-term health and productivity of the vineyard or orchard.