Potential of a Bacillus spp. consortium as a biological control agent of purple spot (Alternaria porri (Ellis) Cif.) and enhancement of shallot growth and production

Purple spot disease caused by Alternaria porri poses a significant threat to shallot plants, potentially leading to yield reductions of up to 40%. Addressing this issue is crucial for maintaining agricultural productivity and ensuring food security. One promising approach to controlling purple spot disease is the utilization of Bacillus spp. consortium, which offers a cost-effective and environmentally friendly solution. In a recent study, researchers aimed to identify the most effective Bacillus spp. consortium for controlling A. porri while also enhancing the growth and yield of shallot plants. The study was employed a completely randomized design (CRD) with seven treatments and five replicates. These treatments included various combinations of Bacillus strains along with positive and negative controls and a fungicide containing mancozeb 80%. The results of the study demonstrated that the consortium treatment consisting of B. pseudomycoides EPL 1.1.4 + B. cereus TLE 2.3 + B. cereus TLE 1.1 + B. cereus SNE 2.2 was the most effective in reducing purple spot disease development. This treatment exhibited a disease incidence of 17.00% and disease severity of 13.33%. Moreover, the consortium treatment significantly promoted the growth and production of shallot plants. Specifically, plants treated with this consortium exhibited a notable increase in plant height, leaf number, and both fresh and dry bulb weights. The enhanced growth parameters included a plant height of 49.83 cm, a number of leaves of 53.33 strands, and fresh and dry bulb weights of 127.08 g and 96.65 g, respectively.