Phaeoacremonium scolyti

Phaeoacremonium scolyti is a pathogenic fungus recognized as a key player in the complex of wood-inhabiting fungi that cause grapevine trunk diseases, most notably esca and Petri disease. The fungus colonizes the xylem vessels, disrupting the hydraulic system of the plant and inducing a slow decline that can eventually lead to the death of the entire grapevine.

This pathogen primarily infects grapevines but can also be found on a variety of woody hosts. Its biological lifecycle is closely linked to wood-boring insects, particularly beetles of the Scolytinae family, which facilitate the entry of fungal spores into the plant's vascular tissue during their boring activities, acting as efficient vectors for the spread of the infection.

Symptoms of an infection include internal wood discoloration, such as dark brown or black streaking observed in cross-sections of the trunk or cordons. Foliar symptoms, which may appear suddenly, often show an interveinal necrotic pattern known as a tiger-stripe effect. These signs indicate that the systemic toxins produced by the fungus have severely impaired the vine’s functionality.

Environmental conditions that favor the spread of the disease include high humidity during pruning periods and the presence of open pruning wounds. The fungus survives in infected wood debris and spreads via wind-borne spores, rain splash, and contaminated pruning equipment. Stress factors such as extreme drought or waterlogging significantly increase the vine's susceptibility to colonization.

The impact of Phaeoacremonium scolyti is detrimental to vineyard longevity, necessitating strict management protocols:

• Strict sterilization of pruning tools using alcohol or bleach solutions.
• Application of fungicide-based wound sealants immediately after pruning.
• Removal and destruction of symptomatic or dead wood from the vineyard.
• Implementation of integrated pest management to control beetle vectors.
• Choosing healthy, certified nursery stock to prevent initial site contamination.