Fungicidal Management of False Smut Disease in Rice Caused by Ustilaginoidea virens

Abstract

False smut of rice caused by the fungus Ustilaginoidea virens has been recorded, in recent years, in the all rice growing areas of State Uttar Pradesh, India. Recommended fungicides are not yet available for chemically controlling the disease. Therefore, uses of unregistered fungicides are common by the farmers, for the management of the disease. The present study, was undertaken to identify effectiveness of fungicides to control false smut of rice. Four systemic fungicides (Propiconazole 25% EC @ 1.0 ml/L, Azoxystrobin 18.2% + Difenconazole 11.4% SC @ 0.5 g + 0.5 ml/L, Azoxystrobin 18.2% @ 1.0 g/L and Tebuconazole 250 EC @ 1.0 ml/L) were evaluated as foliar application in the naturally induced diseased rice, at five different locations in district Siddharthnagar, Uttar Pradesh. Fungicide was applied twice, first at panicle initiation and second at early flowering stage. All the fungicides applied were found effective in controlling the disease. As compared to the untreated (only water application), the fungicide ‘Propiconazole 25% EC’ reduced the maximum disease severity by 93.57%, followed by ‘Azoxystrobin 18.2% + Difenconazole 11.4% SC @ 0.5 g + 0.5 ml/L’, Fungicide Tebuconazole 250 EC @ 1.0 ml/L was found least effective in controlling the disease. It is concluded that more multi-location experiments will be required to reach a decisive conclusion on foliar chemical options for controlling rice false smut disease in eastern parts of Uttar Pradesh.

Effects of Carbon, Nitrogen, Ambient pH and Light on Mycelial Growth, Sporulation, Sorbicillinoid Biosynthesis and Related Gene Expression in Ustilaginoidea virens

“…Yeast extract paste, peptone and beef extract could increase sporulation, and enhance sorbicillinoid production. U. virens adapted to pH values from 3.0 to 8.0, and the optimum pH value for mycelial growth and biomass accumulation was pH 6.0, which was the same as previously reports [60,61]. An acidic environment was more favorable for sorbicillinoid production than alkaline conditions, which was similar to the reports on the production of other mycotoxins, such as patulin [50], aflatoxin [62], and trichothecenes [63].…”

In-vitro and In-vivo Fungicidal Evaluation against False Smut (Ustilaginoidea virens) of Rice

“…Notably, the application of two sprays of propiconazole (0.1%) in this study led to the lowest incidence of false smut disease, the least affected panicles, minimal hill infestation, and the highest grain yield of rice (Barnwal et al, 2012;Kumari and Kumar, 2015). Kumar et al (2020a) stated that application of propiconazole 25% EC (first spray at panicle initiation state and second spray at flowering state) reduced the maximum disease severity by 93.57% followed by azoxystrobin 18.2%+difenconazole. However, contradictory results were reported by Duraisamy et al (2019), indicating that spraying of propiconazole 25% EC at 0.1% during the 50% panicle emergence stage was more effective than trifloxystrobin-tebuconazole at 0.04% at the same stage.…”