Potential Effect of the Nematicide Oxamyl and Surfactant Combinations on Root-Knot Nematode Meloidogyne incognita Infecting Tomato Plants

Abstract

The adjuvants involved in pesticide formulation have a vital role in enhancing the physical properties of active ingredient delivered to the target site in plant-parasitic nematodes. The present study elucidates the potential effect of combinations of the nematicide oxamyl (Vaydate® 24 % SL) and surfactants on the root-knot nematode Meloidogyne incognita infecting tomato plants. Three surfactants namely, Agrimax-3H®, Silwet L-77®, and Sylgard 309® were used at their recommended rats (15 ml/100 L, 5 ml /100 L, and 250 ml/100 L, respectively) as well as the combinations of their respective ¼ R, ½ R, ¾ R with oxamyl at three rates i.e. the recommended (R, 48 mg a.i /plant); ¾ R, 36 mg a.i./plant and ½ R, 24 mg a.i./plant. The results revealed that surfactants caused approximately 50 and 25% hatching inhibition in egg masses and eggs, respectively while oxamyl exhibited the highest egg hatching inhibition by 90% throughout the trial period. The combination of oxamyl and Agrimax-3H showed significantly (P ≤ 0.01) more effectiveness against egg masses (71.17%) or free eggs (55.45% ) hatching as exposure time increase. Moreover, oxamyl potency increased to kill 95% of IJ2 whereas, other surfactants caused a 30% reduction. The mixtures of all tested adjuvants with oxamyl at the recommended rate raised oxamyl potency to kill 100 % IJ2 accompanied by a shortage of oxamyl latent period (LP). Whereas, Agrimax-3H surpassed other surfactants and shorted the LT50 of oxamyl to 0.82 days increasing its nematicidal effect. The addition of surfactants to oxamyl as protective treatment displayed a significant increase in tomato plant growth and suppressed galling of M. incognita while the combination between oxamyl and surfactants as curative treatments showed a vigor control efficacy within oxamyl and Agrimax-3H only and surpassed oxamyl formulation without significant difference.