Journal of Advances in Biology & Biotechnology

Rice false smut, caused by Ustilaginoidea virens (Cooke) Takahashi, has emerged as an increasingly important constraint on rice productivity, particularly under favourable environmental conditions. Effective fungicide selection, coupled with precise application timing, is therefore crucial for minimising disease-associated yield losses. A field experiment was conducted during 2023–24 and 2024–25 to evaluate the efficacy of selected fungicides and their application stages for the management of false smut and to assess their effects on grain yield and economic returns. The experiment comprised ten treatments involving seed treatment with carboxin + thiram @ 2 g kg⁻¹ followed by foliar application of trifloxystrobin 25% + tebuconazole 50% 75 WG @ 0.4 g l⁻¹, azoxystrobin + difenoconazole 325 SC @ 1 ml l⁻¹ and propiconazole 25 EC @ 1 ml l⁻¹ at booting, 50% panicle emergence (PE) and 100% PE, along with carbendazim 50 WP @ 1 g l⁻¹ at 100% PE and an untreated control as check treatments. Pooled analysis revealed marked variation among fungicides and application timings with respect to infected spikelets, infected panicles and grain yield. Azoxystrobin + difenoconazole 325 SC @ 1 ml l⁻¹ applied at 50% PE (T₅) emerged as the most promising treatment, recording the lowest infected spikelets (12.32%) and infected panicles (5.61 m⁻²), compared with 45.38% infected spikelets and 27.62 infected panicles m⁻² in the untreated control. The same treatment produced the highest grain yield of 63.73 q ha⁻¹, representing a 33.2% increase over the untreated control, and recorded the highest benefit-cost ratio (1.81). Across the fungicides evaluated, application at 50% PE consistently outperformed applications at booting and 100% PE, highlighting the critical importance of synchronising fungicide protection with the susceptible reproductive phase of the crop. The findings indicate that judicious fungicide selection combined with timely application can substantially suppress false smut, safeguard yield and enhance the economic viability of rice production. Azoxystrobin + difenoconazole at 50% PE may therefore be considered a promising component of an effective false-smut management strategy.