Integrated use of bacteria and microbial metabolites for management of soil-borne root rot in melon

Abstract Soil-borne pathogens represent a critical constraint to melon ( Cucumis melo L.) production, calling for the development of sustainable biocontrol strategies. This study evaluated the efficacy of formulations integrating bacterial consortia, Trichoderma spp., and microbial metabolites for disease management. A pilot greenhouse study was conducted, and the treatments that provided the lowest disease severity were tested in the field. The field trial followed a randomized complete block design with six treatments and seven replicates: T1 ( Bacillus consortia + Metabolites 1), T2 (Bacterial consortia + Metabolites 2), T3 (Metabolites 1 + Metabolites 2), T4 (Bacterial consortia + Metabolites 1 + Metabolites 2), T5 (standard farm management), and T6 (untreated control). We assessed plant development (stem diameter and shoot dry mass), disease severity, yield components (fruit number and weight), fruit quality (°Brix), and soil health indicators (enzyme activity). Across two experimental cycles, treatments T1 and T4 consistently reduced disease severity by 50% relative to the control. Specifically, T4 significantly enhanced soil health, evidenced by increased activity of β-glucosidase, arylsulfatase, and acid phosphatase (≈ 47, 23, and 120 µg p-nitrophenol g⁻ 1 soil h⁻ 1 , respectively), while achieving a yield of 3.5 fruits per plant. These results demonstrate that the integrated application of microbial consortia and their metabolites provides an effective and viable alternative to conventional chemical management of soil-borne pathogens in melon.