Biological control of onion white rot disease using potential Bacillus subtilis isolates

Abstract Background Onion ( Allium cepa L.) is a very important vegetable crop all over the world, particularly in Egypt for local consumption and exportation. White rot disease most serious of spp. caused by soil-borne fungus Sclerotium cepivorum Berk. Results In this investigation, five tested isolates Bacillus subtilis showed an antagonistic effect significantly reduced linear growth pathogen vitro. B. no. 2 4 highest reduction S. growth, 75.78 74.33%, respectively, while isolate 3 was least effective one, causing 66.67% . Under field conditions at two successive seasons (2019/20 2020/21), bioagent treatments percentage infection than Folicure as officially recommended fungicide. efficacy (78.57 77.78%) followed (74.29 72.22%), lowest (42.86 50.00%), both seasons. All increased dry onion bulb yield improved its quality untreated control plants. The chemical changes total carbohydrates, nitrogen contents, soluble solids (TSS %) enzymes activity related to defense mechanisms treated plants biological were considered. Conclusion This study aimed find agents against white evaluate their on parameters, components quality.