In vitro and field efficacy of fungicides against sheath blight of rice and post-harvest fungicide residue in soil, husk, and brown rice using gas chromatography-tandem mass spectrometry

Abstract

Rice is a staple food for about 65% of the India's population. India ranks first in area under rice and second in production of rice in the world. In India, it is cultivated over 43.39 m ha with a production and productivity of 104.32 million tons and 2404 kg/ha, respectively. Besides ensuring food security of the nation, it is an export commodity and earns a huge foreign exchange. In this study, we investigated the efficacy of five fungicides against Rhizoctonia solani Kuhn AG-1 IA, inciting sheath blight of rice in vitro and under field conditions along with post-harvest residue of the fungicides found effective in disease management. In vitro growth inhibition tests revealed that the EC values of azoxystrobin 18.2% + difenoconazole 11.4% SC, pencycuron 22.9% SC, thifluzamide 23.9% SC, hexaconazole 4% + zineb 68% WP, and validamycin 3% L against Rhizoctonia solani ranged from 0.006 to 354.81 ppm a.i., whereas the corresponding EC values were 0.758 to 1202.26 ppm a.i. Thifluzamide 23.9% SC was found to be the most inhibitory with EC and EC values of 0.006 and 0.758 ppm a.i. followed by hexaconazole 4% + zineb 68% WP. The complete inhibition of sclerotia formation was observed at 1 ppm, 20 ppm, and 25 ppm a.i. of thifluzamide 23.9% SC, hexaconazole 4% + zineb 68% WP, and azoxystrobin 18.2% + difenoconazole 11.4% SC, respectively. In field trials, azoxystrobin 18.2% + difenoconazole 11.4% SC was the best treatment in reducing sheath blight and in enhancing grain yield of rice followed by thifluzamide 23.9% SC, pencycuron 22.9% SC, and validamycin 3% L, whereas hexaconazole 4% + zineb 68% WP was the least effective fungicide. Benefit-cost ratio (B:C) of different fungicides reflected that pencycuron 22.9% SC (B:C 5.06) and azoxystrobin 18.2% + difenoconazole 11.4% SC(B:C 4.65) sprayed at single/recommended doses of 1 ml/l were highly economical in managing sheath blight disease of rice. Double dose of pencycuron 22.9% SC further enhanced the B:C to 7.24 while the double dose of azoxystrobin 18.2% + difenoconazole 11.4% SC was less economical (B:C 2.84) compared to their recommended doses. Samples of rice matrices were processed using QuEChERS method and analyzed for the presence of fungicide residues by gas chromatography-tandem mass spectrometry (GC-MS/MS). The post-harvest residues of azoxystrobin, difenoconazole, and pencycuron, sprayed at single/recommended and double doses with a pre-harvest interval (PHI) of 44 days, were found below the limit of quantification (LOQ), i.e., 0.01 and 0.005 mg kg for azoxystrobin and difenoconazole and 0.05 mg kg for pencycuron in brown rice, cropped soil, paddy straw, and husk. These results clearly demonstrated that treatment of azoxystrobin 18.2% + difenoconazole 11.4% SC and pencycuron 22.9% SC could be taken as safe for crop protection and environmental contamination point of view. The findings of this research work will have a positive impact on rice export and use.

Enhanced Fungicidal Efficacy by Co-Delivery of Azoxystrobin and Diniconazole with Cauliflower-Like Metal–Organic Frameworks NH2-Al-MIL-101

“…Strobilurin fungicides have been the backbone for combating rice sheath blight. Strobilurin fungicide of azoxystrobin (AZOX) is widely used because it works effectively against pathogen infestation [ 15 , 16 ]. AZOX, which belongs to a quinone outside inhibitor, arrests fungal growth via disrupting the electron transport chain, preventing adenosine triphosphate synthesis, and restricting respiration in fungi [ 17 ].…”

Persistence and decontamination studies of chlorantraniliprole in Capsicum annum using GC–MS/MS

“…CAP is a ''reduced risk'' pesticide hence recommended as an alternative to pyrethroids for vegetables (EPA 2008). To create specific, low portion, eco-accommodating pesticides to guarantee wellbeing for purchasers it is important to gauge of pesticide constancy, disinfecting, conduct, non-harmful metabolites, half life period and safe holding up period in consumable deliver (Ahlawat et al 2017;Kumar et al 2018). Since CAP is a new insecticide, a very little work has been carried out on its residues estimation, therefore present study summarises its dissipation pattern, half life and decontamination effects on chilli fruits from consumer safety point of view.…”

Sheath blight of rice: a review and identification of priorities for future research

“…The most popular fungicide application methods practiced for ShB control are foliar spray (McGrath 2004) and seed treatment (Kabir et al 2006). Fungicides restrict the disease development on rice sheaths, acting on R. solani and its sclerotia by various means such as damaging the fungal cell membrane (Roberts et al 1998), acting as enzyme inhibitors (Kumar et al 2018), interfering in key processes including respiration or energy production (Ichiba et al 2000;Lal et al 2017) or by interfering with metabolic pathways associated with sterol and chitin biosynthesis for cell wall formation (Morton and Staub 2008). The best time to apply fungicides in a field is from 7 days after panicle differentiation until heading reaches 50-75% (Uppala and Zhou 2018).…”

“…The above-mentioned fungicides arrest fungal growth via disrupting the electron transport chain, preventing ATP synthesis and restricting respiration in fungi (Ichiba et al 2000). A recent comparison of the effect of Azoxystrobin and of the chemical fungicides thifluzamide, pencycuron, validamycin and hexaconazole showed the chemical fungicides to completely inhibit sclerotia formation while the natural fungicide, Azoxystrobin, also reduced sclerotia formation and resulted in better grain yield (Kumar et al 2018). The use of fungicides has been highly effective for controlling fungal diseases of crops.…”