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, with scant information of their effects on nodulation and growth of cowpea (Vigna unguiculata), had been touted as having potential to serve as bio-nematicide and bio-fertilizer in low-input farming systems. Interactive effects of the southern root-knot nematode (Meloidogyne incognita), Bradyrhizobium japonicum and crude extracts of C. myriocarpus fruit on final nematode population density, nodulation and growth of cowpea variety Eureka were investigated in a 2 × 2 × 2 factorial experiment under greenhouse conditions. At 70 days after the treatments, significant (P ≤ 0.05), first order interactions in Nematode × Cucumis reduced final nematode population densities and nodule numbers by 79% and 20%, respectively. However, in the absence of nematodes, Cucumis increased nodule numbers by 9%. Similarly, Nematode × Bradyrhizobium reduced fresh shoot mass, dry shoot mass and nodule mass by 57%, 59% and 64%, respectively. However, in the absence of nematodes, Bradyrhizobium increased the variables by 50%, 42% and 35%, respectively. Compared to nematode alone, the two interactions had a relative ameliorative effect on the variables measured. Consequently, crude extracts of C. myriocarpus fruit are suitable for use in managing population densities of M. incognita on cowpea production.

► Nematode × Cucumis × Bradyrhizobium interaction was studied in cowpea production.
► Nematode × Cucumis interaction reduced final nematode and nodule numbers.
► Amendment with C. myriocarpus fruit reduced nematode stress on growth of cowpea.
► Thus, nematodes can be managed with Cucumis fruit extracts in cowpea production.