Risk assessment and reduction options for Cryphonectria parasitica in the EU.

Area of Science:

• Phytopathology
• Risk Assessment
• Plant Biosecurity

Background:

• Cryphonectria parasitica causes chestnut blight (Castanea spp.).
• The pathogen is widespread in EU non-protected zones (non-PZs) but absent from protected zones (PZs).
• Virulent strains pose a threat to hypovirulence control and ecosystem services.

Purpose of the Study:

• Assess current EU phytosanitary requirements for C. parasitica.
• Identify risk reduction options (RROs) to preserve PZ status.
• Evaluate regulatory scenarios for pathogen management in the EU.

Main Methods:

• Risk assessment (RA) considering three scenarios: current non-PZ situation (A0), EU without measures (A1), and PZs with additional RROs (A2).
• Evaluation of risks from C. parasitica spread within the EU and introduction from Third Countries.
• Modeling of pathogen spread and impact on ecosystem services under different regulatory frameworks.

Main Results:

• Scenario A2 (current PZs with additional RROs) reduces new C. parasitica introductions by ~5,000 times compared to A0.
• Expected affected EU Member States in 10 years: 2 (A0), 3.5 (A1), and 0.5 (A2) (median values).
• Scenario A1 (no measures) shows the highest relative impact on ecosystem services due to virulent strains.

Conclusions:

• Current EU requirements and additional RROs (Scenario A2) are effective in reducing C. parasitica introduction and spread.
• These measures successfully preserve the protected zone status in EU regions.
• Proactive risk management is crucial for safeguarding chestnut populations and ecosystem services.