Effect of organic amendments on plant parasitic nematodes and soil micro-organisms

Abstract

Field experiments conducted to evaluate the effect of neem and eupatorium leaves at two levels on plant parasitic and non-parasitic nematodes and soil micro-organisms in the rootzone of bhindi and cowpea in rainy and summer seasons revealed that neem and eupatorium leaf treatments (300g/plant or 15 t/ha) were found effective in controlling Helicotylenchus spp., R. reniformis and M. incognita in the rootzone. Lower dose (150g/plant) of neem was found sufficient to suppress the Helicotylenchus spp. In the rootzone of bhindi. Effect of these treatments persisted up to 75 D A S in rainy season and 45 DAS in summer season. The effect of lower doses also persisted up to 30 DAS. The predatory and saprophytic nematode population build up in the rootzone was enhanced by higher dose of eupatorium. The effect on predatory fauna persisted up to 75 D A S in the rootzone of two crops. But in cowpea the effect on saprophytic fauna persisted only up to 60 D A S. The microbial populations (bacteria, fungi and actinomycetes) were increased in the rootzone of bhindi and cowpea in two seasons by the application of eupatorium leaf at higher dose where as neem leaf (higher dose) reduced the microbial population. Only the fungal population increased by the application of neem leaf at higher dose during rainy season. There was seasonal variation in population build up of fungi and maximum effect was seen in rainy season. The biometric characters (number of leaves, height of plant, root weight and shoot weight) and yield of bhindi and cowpea increased significantly by the higher dose of neem and eupatorium leaf. For increasing the height, lower dose of neem, and, for yield lower dose of neem and eupatorium also were found effective. The population of nematodes in the roots at the termination of experiment was significantly reduced by the higher dose of neem and eupatorium in bhindi while lower dose was found effective protecting cowpea roots.