Study on Efficacy of Some Chemical Insecticides on the Incidence of Leaf Folder, Cnaphalocrocis Medinalis (Guenee) Infesting Basmati Rice

Abstract

An investigation was carried out to study the efficacy of some chemical insecticides on the incidence of leaf folder, Cnaphalocrocis medina/is (Guenee) infesting basmati rice in randomized block design with three replications at Crop Research Centre of Sardar Vallabhbhai Patel University of Agriculture and Technology, Meerut during kharif 2011. The population of C. medina/is was first recorded in the second week of August and reached its peak during fourth week of September when mean temperature and relative humidity were 27.30°C and 82.21 per cent respectively. The larval population showed negative correlation with all the weather parameters like maximum and minimum temperature, relative humidity and rainfall. Efficacy of different treatments viz., indoxacarb, fipronil, chlorantraniliprole, cartap hydrochloride, lambda cyhalothrin, triazophos, profenofos, chlorpyriphos and quinalphos on the incidence of C. medina/is in rice crop revealed that all the treatments were found significantly effective in reducing the leaf infestation and thus increasing the yield significantly as compa17ed to control. The most effective treatment in reducing the incidence of C. medina/is was chlorantraniliprole 18.5% SC @ 150 mllha followed by cartap hydroGhloride 50%SP @ 1000 g/ha and fipronil 5%EC @ 750 ml/ha. The quinalphos 25 EC @ 1000 ml/ha was recorded less effective. The highest yield (45.50 q/ha) was obtained from treatment chlorantraniliprole whereas higher cost benefit ratio (9.89) was obtained from treatment fipronil and it is due to higher cost of treatment chlorantraniliprole. The lowest yield (2.20 q/ha) and cost benefit ratio (2.67) obtained from the treatment quinalphos. Chlorantraniliprole was found most safer to spider and coccinellid population followed by fipronil at all observational interval.