Biological control of Phytophthora blight in red pepper (Capsicum annuum L.) using Bacillus subtilis

Phytophthora blight is one of the most important devastating diseases of red pepper plants. Forty-one bacterial isolates were obtained from rhizosphere soil and subsequently tested for antagonistic activity under in vitro and in vivo conditions. Among the 41 isolates tested, 12 exhibited a maximum antagonistic activity in dual culture assay. These 12 isolates were further screened for disease suppression on red pepper plants in both natural and greenhouse conditions. All the antagonists showed varying levels of antagonism, whereas the isolates R33 and R13 exhibited the maximum (86.8 and 71%) ability to reduce the disease severity in in vivo conditions. Based on the 16S rDNA sequencing, the most effective isolates were identified as Bacillus subtilis. In addition, the isolates were also screened for siderophores, hydrogen cyanide and hydrolytic enzymes. Further, the isolates increased the root and shoot length of the red pepper, which is an added advantage of the isolates while performing the desired function.