Field-scale efficacy of bioformulations, bioagents, and fungicides for controlling rice false smut disease: an integrated approach

Abstract

Rice False Smut (RFS) disease (Ustilaginoidea virens) has become a severe problem in many parts of the world. Managing this disease is a major priority as the disease causes a significant yield loss. In the present study, we have investigated the effectiveness of bioformulations, biocontrol agents, and fungicides for managing RFS disease at the lab and field levels. The study evaluated bioformulations LBD 1 and 6, biocontrol agents Trichoderma viride, Bacillus velezensis (P-42 and A-6), and Pseudomonas fluorescens strain Pf-1, and various fungicides such as trifloxystrobin 25% + tebuconazole 50% WG, propiconazole 25% EC, difenconazole 25% EC, flusilazole 12.5% + carbendazim 25% EC, and azoxystrobin 23% SC against RFS. All fungicides tested in the in vitro assay exhibited complete mycelial inhibition against U. virens. On the other hand, biocontrol and bioformulations showed 41.03%–93.53% mycelial inhibition. Pooled data from two seasons (Kharif 2019 & 2020) indicated that all the tested biocontrol agents and fungicides effectively reduced the severity of the RFS disease in field conditions. The fungicide trifloxystrobin 25% + tebuconazole 50% WG at 0.4 gL-1 was found to be the most effective, with the lowest disease severity of 18.23%, followed by 20.24% severity by flusilazole 12.5% + carbendazim 25% EC at 1.0 mLL-1. Fungicides were found to be the best for the management of the disease among different treatments. This is the first comprehensive record of successfully managing the RFS disease using seaweed extracts, fungicides, and microbial bioagents and to standardize the spray schedule for better disease control.

Keywords

• Rice false smut
• fungicides
• bioagents
• bioformulations
• management
• IDM