The Antifungal Effects of Four Tomato Rhizosphere Bacillus spp. against Alternaria Alternata

Biocontrol of early blight disease, through the use of natural alternatives to pesticides was studied by using four Bacillus spp. (B. subtilis, B. megaterium, B. pumilus and B. cereus). The antifungal effects of four Bacillus species isolated from tomato rhizosphere were tested against A. alternata (Fr. ) Keissl. in vitro and in vivo pot experiment which repeated for two seasons 2007/2008 and 2008/2009. The in vitro growth rates of A. alternata were always lower when it was treated with any of the four Bacillus species in comparison with the untreated control. Statistical analysis revealed that the use of B. subtilis and B. megaterium significantly (P 0.05) suppressed the growth of A. alternata in vitro. In the in vivo pot tests, tomato plants treated with the four Bacillus species displayed suppressed disease incidence and disease severity. This study highlighted the promising effect of the four bacteria species tested in reducing disease incidence and severity in comparison with the control treatment and attempting to include non-toxic bio-agent in an integrated management of early blight disease.