Bio-efficacy of Indigenous Technical Knowledges (ITKs) Formulations against Rice Blast Incited by Pyricularia oryzae

Abstract

Rice blast incited by Pyricularia oryzae Cavara [Teleomorph: Magnaporthe oryzae (Hebert) Barr] is a major constraint to rice production, with conventional chemical control often limited by environmental hazards, rising input costs and pathogen resistance. This study evaluated the bio-efficacy of traditional Indigenous Technical Knowledges (ITKs) formulations against P. oryzae under in vitro, pot culture and field conditions. Surveys across the Cauvery delta region identified isolate Pg7 (Aduthurai; GenBank accession: ON556555) as the most virulent strain, inducing 38.99% Per cent Disease Index (PDI) under artificial inoculation. In vitro poisoned food assays demonstrated that Panchagavya, Mint leaf extract, Five-leaf extract and Fish amino acid (FAA) achieved peak mycelial inhibition at an optimal concentration of 15%. Under pot culture, the four-component consortium (T7: Panchagavya + Mint + Five-leaf extract + FAA as seed treatment @ 20 mL/kg and foliar spray @ 15% at 30 and 50 DAT) suppressed blast severity to 13.20% PDI, matching the standard chemical check Propiconazole 25 EC @ 0.18% (13.32% PDI) while boosting grain yield (37.20 g/plant). In field evaluations, the three-way consortium (T5: Panchagavya + Mint + Five-leaf extract) restricted blast severity to 13.78% PDI (compared to 42.34% PDI in untreated control), achieved a grain yield of 4.50 t/ha. Overall, standardized ITKs consortia offer a sustainable and ecologically sound bio-management alternative to synthetic fungicides in blast-endemic rice ecosystems