Efficacy of bioagents and plant extracts for the management of sheath rot of rice caused by sarocladium oryzae

Studies on the in vitro and in vivo antagonistic activity of native bioagents agents and plant extracts were evaluated against Sarocladium oryzae, which causes sheath rot of rice, were undertaken in the Department of Plant Pathology of the Annamalai University, Chidambaram. It was revealed that isolate- Pf S5 (Pseudomonas fluorescens-Sivapuri) recorded the maximum inhibition zone of 10.55 mm and a minimum of 23.40 mm mycelial growth of S. oryzae accounting for 74.00 per cent reduction in the mycelial growth over control and isolate- BsA1 (Bacillus subtilis Ambigapuaram) recorded the maximum inhibition zone of 9.92 mm and a minimum of 24.62 mm mycelial growth of S. oryzae accounting for 72.64 per cent reduction in the mycelial growth over control. Among the ten plant extracts tested (10% concentration) against the mycelial growth of S.oryzae, E. globules extract recorded the minimum mycelial growth (19.03 mm) and maximum per cent reduction of mycelial growth of pathogen (78.85%) over control. In the pot culture studies, seed treatment with Fluorescent pseudomonads (PfS5) @12g/kg plus B. subtilis (BsA1) @12g/kg plus E.globules extract@10% followed by foliar application with Fluorescent pseudomonads (PfS5) and B. subtilis (BsA1) each @ 0.5% plus E. globules extract@10%-T9 at 45 and 60 DAT recorded minimum sheath rot incidence(12.53), maximum plant growth (109.68 cm), number of tillers per hill (15.35), number of grains per panicle (145.90),weight of 1000 of seeds (24.22g) and yield (18.39g/plant).