Biocontrol potential of Bacillus velezensis against Fusarium foot rot in durum wheat: insights from in vitro and in vivo trials

Among diseases affecting wheat crops, Fusarium foot rot (FFR) is the most widespread and harmful in the Mediterranean area. Cilus® Plus (IT 45) preparation, containing the microorganism Bacillus velezensis, was evaluated for the control of FFR. Firstly, Fusarium spp. isolates associated with FFR were collected and identified from durum wheat plants in 11 representative cereal areas of Sicily. Subsequently, 33 strains from all Fusarium spp. were tested in vitro by the dual culture method. In comparison to controls, Cilus® Plus was effective in reducing mycelial growth of eight Fusarium species to various extents from 60.2% for Fusarium crookwellense to 26.8% for Fusarium acuminatum. In vivo trials were arranged in a randomized block design inoculating the sterile soil mixture with a conidial suspension of Fusarium culmorum, the most common and dangerous species. Cilus® Plus was applied either as seed treatment (T1), spray treatment (T2), or both seed and spray treatments (T3). The inoculum density of the pathogen was significantly decreased (-70%) by the T2 treatment, whereas disease incidence was significantly reduced by all treatments with an average reduction of 59.8, 56.5, and 37.5% for T3, T2 and T1, respectively. Disease severity was also significantly reduced by 55.2, 51.5, and 26.7% for T3, T2 and T1, respectively. These data revealed the efficacy of the Cilus® Plus formulation in controlling in vitro the growth of FFR pathogens and, in vivo, pathogen burden and FFR disease development due to F. culmorum.