Management of rice sheath blight caused by Rhizoctonia solani Kuhn. using environmentally friendly method-an alternative to fungicides

Abstract

Paddy is the second crop where huge amounts of chemicals are used for production, majorly for disease control. To avoid excess use of chemicals in the rice fields and also to find the best alternative solution to fungicides for sheath blight disease caused by Rhizoctonia solani, research was carried out by using various bioagents, plant extracts and synthetic bio-polymers. Prior to the field experiments, in vitro studies were carried out to check the efficacy of various bio agents and plant extracts by using dual culture and poisoned food techniques, respectively. Trichoderma harzianum showed the highest mycelial growth inhibition (60.37%), followed by Pseudomonas fluorescens (54.4%), and the least effective was showed by T. asperellum (37.44%). The field experiments were carried out in Kharif 2019-20 and 2020-21, to test the fruitfulness of in vitro studies along with some biopolymers. In Kharif 2019-20 out of all the treatments, effective treatment with least mean disease severity was observed in chitosan (12.50%) and nano silicon (14.79%) application when compared to the fungicide hexaconazole 5 EC (13.89%) which was used as a positive control and the least effective treatment was observed in seaweed extract (18.81%), followed by T. viride (19.0%) whereas, the untreated control showed 28.73% of disease severity. In Kharif 2020-21 chitosan (18.77%) and nano silicon (23.95%) treatments were effective when compared to the hexaconazole 5 EC (23.21%) and highest disease severity was observed in seaweed extract (37.0 %), followed by T. viride (34.81%), whereas the untreated control showed 51.6 % of mean disease severity.