Interacting effects of botanicals, biocontrol agents, and potting media on Rhizoctonia solani led damping-off of okra seedlings

The interacting effects of botanicals, biocontrol agents, and potting media against the Rhizoctonia solani led damping-off in okra (Abelmoschus esculentus L.) were investigated. The treatments comprised of different combinations of extracts of five botanicals: wood apple/Indian bael – Aegle marmelos L., Neem – Azadirachta indica A. Juss, Turmeric – Curcuma longa L., Ginger – Zingiber officinale Roscoe, and Onion – Allium cepa L., and two biocontrol agents, Pseudomonas fluorescens and Trichoderma viride as first factors and two potting media; vermicompost with soil and farm yard manure with soil as the second factor in a completely randomized design with 42 treatments and 4 replications. The seeds were sown after pathogen inoculation. Okra seedling health was recorded daily for the first 16 days after sowing. Pseudomonas soil treatment and Pseudomonas + onion seed treatment showed the least pre-emergence damping off (35%). Almost all the combinations of wood apple extracts showed inhibitory effects on seed germination and growth of seedlings. The greatest number of days for the onset of post-emergence damping-off was recorded with Pseudomonas + Onion seed treatment (14.88 days) followed by Pseudomonas seed treatment (14.13 days). Germination Index (GI) was better for farm yard manure (0.32) than Vermicompost substrates (0.23). The GI was greatest in Pseudomonas soil treatment (0.53) followed by Pseudomonas + Onion seed treatment (0.51). Similarly, Dickson Quality Index (DQI) was greatest for Pseudomonas + Neem seed treatment (0.0015), with a greater value of DQI indicating better seedling quality. No significant interaction was observed between the substrates and biocontrol agents for any studied parameters. Pseudomonas + Onion seed treatment and Pseudomonas soil treatment were most effective for controlling R. solani-led damping-off in okra