Studies on Population Dynamics and Management of Yellow Stem Borer, Scirpophaga Incertulas (Walkar) and Leaf Folder, Cnaphalocrocis Medinalis (Guenee) Using Newer Insecticides and Biopesticides in Rice

Abstract

An investigation was carried out to study the population dynamics and management of yellow stem borer, Scirpophaga incertulas (Walker) and leaf folder, Cnaphalocrocis medinalis (Guenee) using newer insecticides and biopesticides in rice at Crop Research Center of Sardar Vallabhbhai Patel University of Agriculture and Technology, Meerut (U.P.) during Kharif, 2018. During the crop season, 13 insect species were found to attack basmati rice at various crop growth stages. Among them, yellow stem bore, Scirpophaga incertulas Walker and leaf folder, Cnaphalocrocis medinalis, Guenee were recorded as major pests. The first infestation of yellow stem borer was recorded on first week of August and reached its peak during first week of October when temperature, relative humidity and rainfall ranged from 20.70 to 35.90 0C, 58.90 to 96.10%, and 0.00 mm, respectively. The population of leaf folder was first recorded on first week of August and reached at maximum level during last week of September when mean temperature, relative humidity and rainfall ranged from 27.80 0C, 74.85% and 37.0 mm, respectively. The population of yellow stem borer and leaf folder showed negative correlation with minimum and maximum temperatures, evening relative humidity and rainfall while morning relative humidity showed the positive correlation. Efficacy of different insecticides and biopesticides viz, rynaxypyr 20 SC, lancergold 51.8SP (acephate 50 % + imidacloprid 1.8 %), lambda cyhalothrin 5 EC and Beauveria bassiana 1x108 cfu, Metarhizium anisopliae 1x108 cfu and neem oil 1500 ppm against yellow stem borer and leaf folder revealed that all treatments were found significantly effective in reducing the infestation and increase the yield as compared to control. The most effective treatment in reducing the infestation of both the insects was rynaxypyr 20 SC @ 150 ml/ha followed by lancergold 51.8 SP (acephate 50 % + imidacloprid 1.8 %) @ 750 g/ha. The highest grain yield (41.00 q/ha) and higher cost benefit ratio (1:4.40) were obtained from rynaxypyr 20 SC @ 150 ml/ha. The lowest yield (32.86 q/ha) and cost benefit ratio (1:1.45) were obtained from neem oil 1500 ppm @ 3 lt/ha.