Lettuce and French bean production are severely infected by root-knot nematode, Meloidogyne incognita which causes critical damage to economic plants. Therefore, the farmers have to use chemical nematicides with or without adding adjuvants to enhance the active ingredient delivery to the target nematode. A current study was conducted to assess the direct effect of three adjuvants namely Silwet L-77, Sylgard 309 and Agrimax 3H comparing with three formulations of oxamyl, fosthiazate and fenamiphos on root-knot nematode Meloidogyne incognita. In vitro experiments, ovicidal effect of Silwet L-77, Sylgard 309 and Agrimax 3H on eggs hatching of root-knot nematode was close to the lowest efficient nematicide fenamiphos when the adjuvants were applied at double recommended rate but their effect does not rise to the level of oxamyl or fosthiazate. On the other hand, mortality percentages of second-stage juveniles resulted from Silwet L-77, Sylgard 309 and Agrimax 3H at the recommended rate were 37.33, 50.00 and 42.19 %, respectively. Whereas, double recommended rate of such materials induced mortality percentages reached 46.66, 47.83 and 48.66 %, respectively comparing with 90.83,74.33 and 45.83% resulted from the tested nematicides oxamyl, fosthiazate and fenamiphos, respectively. On the other hand, controlling the root-knot nematode infecting lettuce and French bean plants under greenhouse conditions revealed that adjuvants have weak or limited nematicidal effect with minor potency in reduction nematode development incomparable with the tested standard nematicides, and does not rise to the lowest effect of a tested nematicide fenamiphos. However, both tested plants showed no visual phytotoxicity symptoms.