Studies on esterified oils of Thevetia nerifolia, Ricinus communis and neem, Tagetes patula leaves with Triazophos against Meloidogyne incognita and Rotylenchulus reniformis

Antinematicidal properties of Thevetia nerifolia leaves were extracted with Benzene, Chloroform, Ethyl acetate and Methanol tested in vitro against J₂ of Meloidogyne incognita. Cent per cent mortality was obtained in Ethyl acetate and Methanol extracts, however, Ethyl acetate resulted 100% mortality of J₂ of M. incognita at 62.5 ppm concentration thus found lowest penetration in cowpea seedlings (55, 43 & 22 J₂) in 24, 48 and 72 hrs exposures, respectively. In pot study, esterified oil of Thevetia and Ricinus significantly enhanced shoot weight of cowpea cv. P-578 and decreased Rotylenchulus reniformis population, maximum being in higher concentrations (500 ppm). In a Field trial, data recorded showed that the plant leaves extracts applied in the plots had profound effect on the weight of the cowpea plants as compared to control. Maximum weight was found to be in Tagetes leaves treatments followed by neem leaves. As against this, nematode population (mainly

R. reniformis) was lowest in Tagetes leaves, probably nematicidal principles found associated with Tagetes had adverse effect on nematode population and thus enhanced the plant growth of cowpea.