Eutypa dieback

Eutypa dieback, caused by the ascomycete fungus Eutypa lata, is a devastating disease affecting woody perennial plants. It is primarily known for causing trunk and cordons necrosis, leading to stunted growth and the eventual death of the plant. The fungus colonizes the woody tissue, slowly spreading through the vascular system.

The pathogen has a wide host range, significantly affecting crops such as grapevine, common apricot, common cherry, duke cherry (Prunus cerasus × avium), and pistachio. Because the fungus can persist in dead wood for several years, it remains a constant threat in orchards and vineyards where sanitation is neglected.

Early symptoms are most visible during the spring, characterized by stunted shoots, short internodes, and small, chlorotic, or cupped leaves. As the disease progresses, a cross-section of the trunk or cordon reveals a distinct wedge-shaped area of dark, necrotic wood, which eventually becomes hard and brittle, leading to the collapse of the affected branches.

The spread of Eutypa dieback is driven by ascospores, which are released during rainfall and dispersed by wind. Infection occurs exclusively through pruning wounds. Once the spores germinate in the wound, the mycelium penetrates deep into the sapwood, making it resistant to topical chemical treatments once the colonization is established.

Effective management requires a proactive approach to wound protection and orchard hygiene. Essential practices include:

• Scheduling pruning activities during dry periods to minimize spore infection risks.
• Applying fungicide-based pruning wound sealants immediately after cuts.
• Removing and burning all symptomatic wood showing internal necrosis.
• Ensuring proper spacing to facilitate air movement and minimize humidity around the main trunks.