Evaluation of the e?ectiveness of Candida oleophila against Penicillium expansum in postharvest storage

Penicillium expansum is a major postharvest pathogen of apples, primarily infecting through wounds incurred during harvesting. This study evaluated the effectiveness of Candida oleophila (CO) as an alternative to chemical treatments for managing blue mould. Apples were injured and inoculated with P. expansum (10⁶ conidia/ml), then treated with CO or pyrimethanil 24 hours before or after inoculation. Negative controls received water. Treated fruits were stored at 1.5°C and 90% relative humidity for 60 days, and disease incidence was assessed every 7 days using three severity categories (low, medium, severe). Results showed minimal symptoms on non-injured fruits. After 35 days, CO treatment reduced disease incidence to 1.67% (pre-inoculation) and 4.67% (post-inoculation). However, after 56 days, disease incidence was high on injured and CO-treated fruits, reaching 95% for pre-inoculation treatments. Pyrimethanil provided moderate control, with 21.67% disease incidence when applied pre-inoculation and 26.7% post-inoculation. Findings indicate that under high inoculum pressure, CO is ineffective in controlling blue mould of apples, highlighting the limited applicability of this biocontrol agent for postharvest disease management.