Potential of Sequentially Introduced Biocontrol Consortia in Suppressing Fusarium Basal Rot in Shallot

Microbial consortia have become a promising alternative to control plant disease biologically. However, the performance of microbial consortia might be less effective in disease control when applied simultaneously. Therefore, this study was aimed to evaluate the efficacy of microbial consortia in suppressing Fusarium basal rot (FBR) disease using sequential introduction. This study was carried out using Completely Randomized Design with four treatments, consisting of control treatment (no consortia added) and four treatments of consortia application with different isolate compositions as well as order of introduction. Microbial consortia (composed of Trichoderma asperellum PBt1 and three strains of Bacillus cereus (PBt2, PBt3, and LBM-H1C) were introduced to the shallot var. Bauji grown in living soil under greenhouse condition. FBR severity and shallot growth were observed. The results confirmed that sequentially introduced microbial consortia could improve the performance of FBR control compared to those inoculated simultaneously and to the control (no consortium added). Of all treatments tested, the highest FBR suppression (28.54% at 42 days after planting) was obtained from the sequential application of T. asperellum PBt1 followed by B. cereus PBt2 then by B. cereus LBM_H1C. This treatment also improved the plant weight significantly compared to that of plants with no microbial consortia applied. © 2025 Published under licence by IOP Publishing Ltd.