Efficacy of Pantoea agglomerans strain RK-84 in controlling fire blight caused by Erwinia amylovora in pear orchards

Erwinia amylovora is a bacterial pathogen responsible for fire blight, a devastating disease that affects apples, pears, and other plants in the Rosaceae family worldwide. Biological control is considered an environmentally friendly alternative to chemical treatments, with Pantoea agglomerans strains playing a key role. This study aims to assess the efficacy of P. agglomerans strain RK-84 in controlling fire blight caused by E. amylovora in pear orchards in two regions of Türkiye, Amasya and Antalya. In this experiment, a suspension of P. agglomerans RK-84 at a density of 10⁵ CFU/mL was sprayed on trees at three time points: at the onset of flower blossom, two weeks later, and ten days following the second application. As a positive control, Bacillus subtilis QST 713 was applied at a concentration of 10⁷ CFU/mL (Serenade^® ASO, Bayer CropScience). Results indicated that P. agglomerans RK-84, at a concentration of 10⁵ CFU/mL, reduced disease incidence with an efficacy of 86.04% in Amasya and 84.28% in Antalya, showing no significant difference from the positive control, which achieved efficacy rates of 86.68% in Amasya and 84.89% in Antalya.