Nematicidal Activity of Newbouldia laevis (P. Beauv.) Seem. Leaf Extract Against Root-Knot Nematode (Meloidogyne javanica (Treub.) Chitwood on Eggplant (Solanum spp.) in Jalingo, Nigeria

Abstract

Solutions to problems of pests ravaging man’s crops abound in nature and are known to be quite soft on the environment. Extracts of leaves of Newbouldia laevis were assayed for activity against the rootknot nematode, Meloidogyne javanica. The treatments which included the crude extract, 5 ml and 10 ml dilutions and Control as distilled water were used both in the laboratory and field experiments. Twelve petridishes containing 1000 nematode eggs and another 12 petridishes containing 1000 juveniles were each treated with the extracts and arranged in complete randomized design. Results showed the crude extract was the most effective in reducing the hatching of M. javanica eggs (90.33%) and caused greater mortality of juveniles (93.10%) than all other treatments. In the field experiment, twelve 2 m x 2 m-sized prepared plots were transplanted with nine three week old seedlings of ‘Eggplant cv Yar Bello’ into holes drenched with 10 ml of appropriate treatment. Ten ml of these treatments were drenched into soil around the plants weekly for eight weeks. Result showed that the crude extract performed better than other treatments in all parameters some of which included plant height (112.77 cm in 2017; 113.33 cm in 2018), number of leaves  (120.00 in 2017; 120.77 in 2018), number of fruits  (35.44 in 2017; 35.88 in 2018), fruit weight  (73.81g in 2017; 74.44 g in 2018), yield  (58.70 tons/ha in 2017;59.94 tons/ha in 2018), final nematode population  (159.66 in 2017; 149.26 in 2018) and reproduction factor  (0.42 in 2017; 0.39 in 2018). In conclusion, extract of N. laevis particularly the crude extract shows potential for managing M. javanica and allowing for profitable cultivation of ‘Eggplant cv Yar Bello’.