Nematotoxicity and Structure-activity Relationships of Aryl 2-chloroethyl ethyl phosphates against Root-knot Nematode Meloidogyne incognita

Nineteen O-aryl O-2-chloroethyl O-ethyl phosphates were screened for their nematicidal activity against Meloidogyne incognita. In vitro, 0–2, 4, 6-trichlorophenyl-0-2-chloroethyl-0-ethyl phosphate expressed maximum activity (LC₅₀ = 23.22 ppm). Quantitative structure activity relationship studies indicate that molar refractivity for orf/zo-substifuents (MR₍₀₎) and STERIMOL length parameter forpara-substituents (L_(p)) contribute about 87% towards the activity of phosphate compounds. In vivo testing of five selected compounds showed that four compounds significantly reduced the number of galls in treated plants compared to untreated control plants. None of the tested compound expressed phytotoxicity.