Biological control of plant-parasitic nematodes by neem products in agricultural soil

Various products prepared from neem (Azadirachta indica) such as leaf powder, sawdust and oilseed cake, and urea were tested for their activities against plant-parasitic nematodes (Hoplolaimus indicus, Helicotylenchus indicus, Rotylenchulus reniformis and Meloidogyne incognita juveniles), a predatory nematode (Dorylaimus elongatus), free-living nematodes and the growth of chickpea (Cicer arietinum) in the field. Soil-amendments with these materials resulted in a significant decrease of plant-parasitic nematodes relative to control plots. In contrast, populations of predatory and free-living nematodes increased. Oilcake was most effective, though all the neem products and urea markedly suppressed plant-parasitic nematodes. However, leaf powder increased populations of predatory and free-living nematodes. All treatments resulted in increased fresh and dry weights and the height and number of pods on chickpea plants. (C) 1998 Elsevier Science B.V.