Evaluation of Bacillus amyloliquefaciens Strain TV-17C as a Potential Biocontrol Agent Against Postharvest Blue Mold in Oranges

Postharvest blue mold, caused by Penicillium italicum Wehmer, is a major constraint in citrus production, leading to considerable economic losses during storage and transportation. In this study, the efficacy of Bacillus amyloliquefaciens strain TV-17C was evaluated as a biological control agent against P. italicum on ‘Washington Navel’ oranges under both in vitro and in vivo conditions. The bacterium significantly inhibited the mycelial growth of P. italicum in dual-culture assays, achieving an inhibition rate of 95.82%. In storage trials conducted in two major citrus-producing regions in Türkiye (Hatay and Mersin), different concentrations of TV-17C (150, 200, and 250 mL/100 L water; 107 CFU mL−1) were tested. The highest efficacy was recorded at 250 mL/100 L, with disease reduction rates of 91.09% and 90.29% in Hatay and Mersin, respectively, comparable to the chemical fungicide fludioxonil (TEACHER 230 SC), which achieved 92.08% and 90.29%, respectively. Notably, no statistically significant difference was found between the performance of B. amyloliquefaciens TV-17C and fludioxonil. These results highlight the potential of B. amyloliquefaciens strain TV-17C as a safe, effective, and environmentally sustainable alternative to chemical fungicides for managing postharvest blue mold in citrus fruits.