Bacterization with Endospore-forming Bacillus spp. Promotes Plant Growth and Suppresses Foot Rot Disease in Black Pepper (Piper nigrum L.) in the Nursery

Abstract

Foot rot disease (Phytophthora capsici) causes severe economic losses to cultivators of black pepper. Fungicides used for managing the disease adversely affect the export potential of the product due to their residual toxicity. Endospore-forming bacterial strains, Bacillus amyloliquefaciens VLY24, Bacillus pumilus VLY17, and Bacillus velezensis PCSE10 were evaluated for growth promotion and disease suppression in black pepper nursery at two locations in Kerala, India. All the isolates could suppress Phytophthora capsici under in vitro conditions. Spraying detached leaves with a cell suspension of the bacterial isolates could delay the development and progression of lesion. In the in vivo trials, bacterized cuttings had a better establishment in the nursery when compared to uninoculated control. Plant growth parameters like the number of leaves, roots, and shoots were more in bacterized cuttings. Cuttings treated with Bacillus pumilus VLY17 when challenge inoculated with the pathogen, showed 84.74 percent reduction in the size of lesions on the leaves, and showed the least disease index (0.27) compared to pathogen inoculated control. It is proposed that endospore forming Bacillus spp. with anti-oomycetic activity could be potential biocontrol agents against foot rot disease of black pepper.