Evaluation of rhizobia inoculants and fungicides in the management of fusarium wilt disease of cowpea (Vigna unguiculata (L.) walp)

Abstract

ABSTRACT

The antifungal potential of Rhizobia inoculant (Ri) and its compatibility with fungicides in controlling Fusarium oxysporum f. sp. tracheiphilum (FO) in cowpea was investigated. Fifty cowpea nodules were collected from fields in Kano and Ibadan, isolation, authentication and identification of Rhizobia were carried out. Antagonistic potential of best two strains (R2 and R3) were tested in-vitro on FO with USDA 2677 (R1) as reference. Fungicides and Rhizobium compatibilities were carried out on seeds dressed with the four fungicides. Seeds were thereafter coated with R1, R2 and R3 and rhizobium strains. Seven local strains (Ibadan1, 2 and 16, Kano18, 19, 42 and 49) were identified as Bradyrhizobia spp. In terms of number of nodules, Ibadan 16 (9) and Kano 19 (7) performed better, compared with Reference Rhizobium (11). Ibadan16, Kano19 and R3 significantly inhibited mycelia growth of FO. The TMD (6.33E +08), IMC (6.25E+08) enhanced growth than MC (4.30E+08) while CM (0.00) inhibited growth of all Rhizobium strains, with control having highest (3.89E+10) CFU/mL. Thiamethoxam + metalaxyl-M + Difenoconazole and Imidacloprid + Metalaxyl + Cabendazim were compatible with Ibadan 16 and Kano 19. Indigenous Rhizobium competed well with exotic strains (USDA 2677) and are recommended for use in cowpea inoculant production.