Field Experiment to Evaluate the Efficacy of Different Doses of Chemical Fungicides against Rice Brown Leaf Spot Disease Caused by &lt;i&gt;Bipolaris&lt;/i&gt;&lt;i&gt; &lt;/i&gt;&lt;i&gt;O&lt;/i&gt;&lt;i&gt;ryzae L&lt;/i&gt;. at Paklihawa, Rupandehi, Nepal

Sunil Shrestha,Binaya Parajuli,Laxman Aryal,Jharana Panthi,Pratibha Sharma,Yogendra Singh Saud

doi:10.12691/wjar-5-3-6

Abstract

Brown Leaf Spot of Rice, caused by the Pathogen Bipolaris oryzae, is one of the important rice diseases resulting in high yield reduction and poor grain quality. A field experiment was conducted to evaluate the efficacy of different doses of chemical fungicides against brown leaf spot in ‘SabhaMansuli’ variety of rice in the research field of Institute of Agriculture and Animal Sciences, Paklihawa Campus from July 15, 2015 to December 1, 2015. The experimental design was RCBD with three replications and ten treatments. Treatments comprised of three different chemical fungicides; SAAF® (Carbendazim 12% + Mancozeb 63%), Tilt® (Propiconazole 25 EC) & Bavistin® (Carbendazim 50% W.P.) at three different doses of 1.5, 2 & 2.5 g (or ml) and a control plot. Among the different fungicides, Tilt® at the rate of 2 ml/lit water showed significantly lowest AUDPC value (373.7) followed by SAAF® at 2 gm/lit (374.9) while the highest value was shown by Bavistin® at 2gm/lit (590.1).Similarly, highest economic yield was obtained in SAAF® at 2gm/lit (5.220 t/h) followed by Tilt® at 2ml/lit water (5.210t/ha) and the lowest in Bavistin® at 1.5gm/lit (3.320t/ha). So, among different chemical fungicides, SAAF® at 2gm/lit being efficient, economical and easily accessible, farmers could be suggested for reducing the disease severity and subsequent increase in the yield of rice.

Highlights

Rice is most preferred staple food crop of Nepal and fulfills about 50% of the total calorie requirement of people
The brown leaf spot disease of rice is one of the most devastating diseases of rice that caused Bengal Famine in 1942 with the yield loss of 50-90% which resulted in the death of about 2 million people due to starvation [9].Among the fungal diseases, brown leaf spot of rice caused by pathogen Bipolari soryzae is a major disease occurring in almost all the rice growing areas of the world causing 5% yield loss across all lowland rice production situations in South and Southeast Asia [11]
The treatments comprised of 3 different fungicides in 3 different doses and a control/check plot to test the efficacy of common fungicides and find out their effective dose in brown spot management

Summary

Introduction

Rice is most preferred staple food crop of Nepal and fulfills about 50% of the total calorie requirement of people. Whereas hills and mountains have 27.53% and 4.14% of total rice area producing 26.19% and 2.97% of rice production with productivity of 3.22 and 2.42 t/ha [8]. The brown leaf spot disease of rice is one of the most devastating diseases of rice that caused Bengal Famine in 1942 with the yield loss of 50-90% which resulted in the death of about 2 million people due to starvation [9].Among the fungal diseases, brown leaf spot of rice caused by pathogen Bipolari soryzae is a major disease occurring in almost all the rice growing areas of the world causing 5% yield loss across all lowland rice production situations in South and Southeast Asia [11]. The pathogen infects the coleoptiles and causes blighting, and turns the leaves oval in shape with dark brown to purplish-brown spots that rigorously damage photosynthetic activity killing the leaf [4]

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Conclusion