Toxicity of plant extracts to meloidogyne incognita in tomato plants

The objective of this study was to evaluate the nematicidal and nematostatic effect of nettle (Fleurva aestuans), neem (Azadirachta indica), castor bean (Ricinus communis) and cassava (Manihot esculenta) bark extracts prepared through different methods. Tomato seedlings were inoculated in the roots region with a suspension containing 3,000 eggs/juvenile Meloidogyne incognita, and after 72 hours 100mL of the plant extracts were added to the soil. After fifty days, plant height, stem diameter, fresh and dry biomass of shoots, fresh and dry biomass of roots, number of galls on roots and number of juveniles in the soil were evaluated. Castor bean and nettle extracts promoted increments in plant height of 48% and 43%, respectively, if compared to water control (positive). Dry biomass of shoots and roots were significantly influenced by the extracts, especially by neem, that provided an increase of 71% and 90% for these variables. The cassava extract, prepared by infusion, provided the greatest reduction in the number of juveniles. Extracts of castor bean and cassava, cooked and prepared by infusion, respectively, reduced the number of galls in 70% and 79%. All extracts regardless the method for preparation, reduced the number of juveniles, especially neem and cassava, which reduced juveniles in 84% and 88%, respectively. These findings look promising for use in sustainable nematode control in tomato crops.