Management of pests and diseases of rice crop with neem products

The efficacy of neem (Azadirachta indica A. Juss.) oil at 3 per cent and neem seed kernel extract (NSKE) at 5 per cent was compared with that of the insecticide phosphamidon against pests and diseases of rice crop in farmer's fields. Rice seedlings raised in nursery, treated with neem cake (at 150 kg/ha as basal application), and seedlings raised with carbofuran 3G (at 3.5 g/m(2) at 10 days after sowing), were planted in main field in separate plots, with suitable controls. Neem oil (NO) and NSKE were sprayed at 500 1/ha on plants that had received neem cake in nursery separately. Phosphamidon (500 ml/ha) was sprayed on plants that had received carbofuran in nursery. Spraying was started immediately after the crossing of Economic Threshold Level (ETL) by any insect or disease. The damage caused by the insect pests leaf hopper (Cnaphalocrocis medinalis Guenee) and brown plant hopper (Nilaparvata lugens Stal.) and sheath blight disease (Rhizoctonia solani Kuhn.) to rice crop were significantly reduced by NO and NSKE and the reduction was comparable to that of phosphamidon. Neem oil and NSKE were not harmful to the beneficial predators lycosa (Lycosa pseudoannulata Bees et Str.) and mirid bug (Cyrtorhinus lividipennis Reuter.) as was the insecticide phosphamidon. Stem borer (Scirphophaga incertulas Walk.), earhead bug (Leptocorisa acuta Thumb.), and brown spot (Helminthosporium oryzae Dreshler) were below ETL in all treatments and there were no differences in the level of incidence between treatments. The yields obtained from neem oil and NSKE treatments were significantly higher than from the control treatment and either comparable or higher than the yield of phosphamidon-treated plants. Similarly, the net gain obtained from neem oil and NSKE treatments was higher than or similar to that obtained from phosphamidon treatment.