The effects of cold and hot aqueous extracts of 5 test plants (Luffa cylindrica, Momordica charantia, Euphorbia hirta, Desmodium scorpiurus and Stachytarpheta cayennensis), wood ash of Gmelina aborea, a synthetic insecticide (Karate –Lambda cyhalothrin) and untreated tap water (control) were evaluated against the egg hatchability and control of Meloidogyne spp. in cowpea (Vigna unguiculata (L.) Walp) in the laboratory and greenhouse. The experiments were laid out in a Completely Randomized Design (CRD) with 13 treatments (Hot water extracts (HWE) and cold water extracts (CWE) of L. cyclindrica; E. hirta, D. scorpiurus, S. cayennesis, M. charantia, wood ash, L. cyhalothrin and control) replicated 3 times. The result of the laboratory experiment showed that the hot and cold water extracts of L. cylindrica and HWE of M. charantia significantly (p < 0.05) inhibited the hatching of nematode eggs. Results obtained from the Greenhouse indicated that HWE of E. hirta, CWE of S. cayennesis, CWE and HWE of L. cylindrica significantly improved cowpea yield, (p< 0.05). The aqueous extracts reduced the number of galls on the roots, nematode populations in the root and soil. The results obtained G. aborea extracts did not differ significantly with the synthetic nematicide – L. cyhalothrin. The leaf extracts of the test plants have potential as sources of botanical nematicides to reduce the devastating effects of plant-parasitic nematodes in cowpea fields.
Key words: Plant extracts, cowpea, lambda-cyhalothtrin, inoculum, nematomde.
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