Coating Seeds with Bacillus amyloliquefaciens PMB05 Combined with Sodium Metasilicate Reduces the Occurrence of Watermelon Fruit Blotch Disease

Bacterial fruit blotch (BFB), caused by Acidovorax citrulli, is a major constraint in watermelon (Citrullus lanatus) production worldwide. As a seed-borne disease, reducing the initial inoculum through seed treatment is critical for effective management. This study evaluated the biocontrol potential of Bacillus amyloliquefaciens PMB05 as a seed treatment to enhance resistance against BFB. Seed treatment and spray inoculation assays revealed that the PMB05 fermentation broth provide superior diseased resistance compared with its powder formulation. To optimize seed treatment performance, the addition of 5% maltodextrin improved bacterial adherence on seed surfaces without affecting germination. In our previous research, the co-treatment of sodium metasilicate and PMB05 enhanced plant immunity and resistance to soft rot in cabbage. In this study, we also incorporated this co-treatment to seed coating. This combination markedly strengthened plant immune responses and reduced BFB incidence, achieving a 70.2 % control efficacy. Overall, the co-treatment of PMB05 fermentation broth and sodium metasilicate in seed coating represents a promising, eco-friendly strategy for managing BFB in watermelon production.