LAUSR

Abstract Sheath blight disease has become a major constraint in cultivation of rice in Guyana inflicting significant yield losses. Eleven plant extracts, three biocontrol agents and five new generation fungicides were screened for their efficacy against sheath blight pathogen, Rhizoctonia solani under in vitro conditions. The extracts of lemon grass, thick leaf thyme, marigold and clove at 15% showed high inhibition to mycelial growth of R. solani. Among biocontrol agents, Bacillus cereus OG2L exhibited high inhibition against mycelial growth of R. solani. New generation fungicides viz., Antracol (Propineb), Nativo (Trifloxystrobin + Tebuconazole), Silvacur Combi (Tebuconazol + Triadimenol), Cyclops (Cinnamon Oil + Clove Oil) and a biofungicide (Serenade - Bacillus subtilis cepa QST 713) recorded complete inhibition of R. solani under in vitro conditions. The plant extracts, bioagent and new generation fungicides that showed high inhibition to R. solani under in vitro were evaluated for their efficacy against shealth blight disease under greenhouse and field experiments. The extracts of lemon grass (7.21; 8.04; 4.85%), thick leaf thyme (6.71; 7.28; 4.71%) at 15%; B. cereus OG2L at 2 g L−1 (7.86; 8.68; 5.09%) and new generation fungicides viz., Antracol 70WP (8.51; 7.79; 5.27%), Nativo (7.62; 7.21; 4.20%) and Serenade (7.78; 7.66; 4.79%) have recorded low percent disease severity compared to untreated control (26.25; 31.16; 20.43%) in greenhouse, field trials I and II, respectively. The plant extracts, bioagent and new generation fungicides recorded a greater reduction (73.63%) in sheath blight disease incidence with an average yield increased from 10.25 to 36.03% compared to the control. The current study has provided chemical and non-chemical options for an integrated management of sheath blight disease in rice plants.