Biological control of damping-off and root rot disease caused by Rhizoctonia solani on cucumber plants

Abstract

Damping-off and root rot is a serious disease infecting cucumber on both seedling and adult stages under protected cultivation causes severe losses in the cucumber yield. Thirteen biocontrol agents i.e. six Trichoderma spp., five Bacillus spp. and two species of actinomyces were tested for their ability to control of cucumber damping-off and root rot disease caused by Rhizoctonia solani in vitro and in vivo and their ability to promoting growth of cucumber plants. Trichoderma asperellum, Bacillus subtilis1, Pseudomonas fluorescens and Streptomyces spp1 act to be highly efficient bioagnts to inhibit mycelial growth of Rhizoctonia solaniin in vitro. All tested bio agents of T. asperellum, B. subtilis1, P. fluorescens and Streptomyces spp1 significantly reduced pre-and post-emergence damping off and root rot disease incidence causing by R. solani in both Fayoum and Giza governorates experiments under greenhouse conditions as seed and seedling treatment. Also, these treatments significantly increase growth parameters and yield components compared with the check treatment. All treatments had considerable increase in the peroxidase, polyphenol oxidase, catalase enzymes and total phenol activities that play an important role in plant defense mechanisms against pathogens infection. These results proved that bioagent i.e. Pseudomonas flourecens is an efficient method as to control the causal pathogen of damping-off and root rot of cucumber.