Postharvest bioassay of mandarin fruits against blue mold (Penicillium italicum) using sustainable management approaches

Blue mold is a major postharvest disease of mandarin, causing substantial losses during storage. This study evaluated the efficacy of GRAS (Generally Regarded as Safe) salts, botanical extracts, and physical methods to manage blue mold in Doti Local mandarin at Tikapur, Kailali. In vitro and in vivo experiments were conducted in a completely randomized design, with carbendazim as the chemical check. Five botanical extracts (lemongrass, sweet flag, lantana, garlic, and neem oil) and six GRAS salts (potassium metabisulfite, sodium carbonate, ammonium carbonate, sodium salicylate, sodium sulfite, and copper sulfate) were tested in vitro using the poisoned food technique. In vivo, these treatments, along with UV radiation and hot water, were assessed for disease reduction. All treatments significantly suppressed radial mycelial growth in vitro by day 7. Carbendazim (50 and 100 ppm) completely inhibited mycelial growth, while neem oil (100 ppm) showed over 60% inhibition. Lantana (10%), sodium salicylate (25 mM), and sodium sulfite (25 mM) recorded over 50% inhibition. In vivo, neem oil, garlic extract, and sodium carbonate recorded 24-31% disease inhibition, while carbendazim showed the highest (47.13%). Garlic extract and neem oil consistently reduced pathogen growth, showing their potential as safer, sustainable pre-storage management options for blue mold.