Interactive effects of Meloidogyne incognita race 2, Bradyrhizobium japonicum and crude extracts of Cucumis myriocarpus fruit on Vigna unguiculata

Crude extracts of wild cucumber (Cucumis myriocarpus) fruit, without information on their effects on nodulation, had been touted as having potential as a nematicide and a fertiliser in low-input cowpea (Vigna unguiculata) production systems. Interactive effects of the southern root-knot nematode (Meloidogyne incognita), Bradyrhizobium japonicum and crude extracts of wild cucumber (C. myriocarpus) fruit on each other and growth of cowpea variety Eureka were investigated in a 23 factorial experiment. At harvest, 70 days after initiating the treatments, significant (P ≤ 0.05) first order interactions between any two of the three main factors on variables measured were observed, with interactive effects being either stimulatory or inhibitory. Crude extracts of C. myriocarpus fruit were basically suppressive on nematode numbers but stimulated nodulation and growth of cowpea. Consequently, the material is suitable for use in managing population densities of M. incognita on cowpea production in low-input cowpea production systems.

► The ground-leaching technology (GLT) widely used in Limpopo Province, South Africa, in management of plant-parasitic nematodes, ameliorates the drawbacks of conventional organic amendments.
► Using crude extracts of Cucumis myriocarpus fruit in the GLT, in this study suppressed Meloidogyne incognita numbers and improved nodulation by Bradyrhizobium japonicum and growth of cowpea.
► The material also ameliorated nematode effects on nodulation and growth of cowpea.
► Consequently, GLT system using this material fits well with low-input and environment-friendly pest management systems in legume production.