Root Extracts of Plants to Control Root-Knot Nematode on Edible Soybean

Chemical control of plant-parasitic nematodes, essentially, involves the use of synthetic nematicides. However, apart from its very high cost, increased concern for the environment has necessitated a reduction in the amount of nematicide used for nematode control. Additionally, there has been an increase in the intensity of search for other efficient, ecologically sound and safe control methods. Meloidogyne incognita (Kofoid and White) Chitwood, eggs were exposed to concentrations of root extracts of Siam weed [Chromolaena odorata (L.) King and Robinson], Neem (Azadirachta indica A. Jass), Castor bean (Ricinus communis L.) and Lemon grass (Cymbopogon citratrus (DC.) Stapf). One hundred percent concentration of root extracts of Siam weed and Neem exhibited 100% inhibition of egg hatch and larval mortality. While 100% concentration of root extracts of Castor bean and Lemon grass exhibited 93 and 95% inhibition of egg hatch and 62.1 and 75% larval mortality respectively. Egg inhibition and larval mortality decreased with an increase in the dilution of all the extracts. Similarly with an increase in exposure time, juvenile mortality was also increased. Significant differences were also observed in the concentrations of the root extracts in respect of the two parameters.