Field suppression of Fusarium wilt in banana using combined application of native endophytic and rhizospheric bacterial isolates possessing multiple functions.

Abstract

To develop effective biological control methods for management of Fusarium wilt of banana, 71 endophytic bacteria were isolated from root and corm tissues and 37 bacteria were isolated from the rhizospheres of 21 different banana accessions. The in vitro screening of these microbes against Fusarium oxysporum f.sp. cubense (causal agent of Fusarium wilt in banana) demonstrated that six endophytic and four rhizospheric bacterial isolates reduced the severity of Fusarium wilt while not totally suppressing the disease. These effective bacteria were mixed in different combinations and evaluated in cv. Grand Naine. Soil applications of five different combinations resulted in complete suppression of Fusarium wilt and increased plant growth parameters and number of roots compared to control plants. Field evaluation of these five combinations of bacterial isolates in an area of heavy inoculum and using cv. Grand Naine indicated that all the bacterial combinations suppressed Fusarium wilt and increased the number of banana hands (up to 155%) and bunch weight (up to 214%) as compared to untreated controls. These bacterial antagonists survived in the rhizosphere for up to 35 d and completely colonized roots, corms, pseudo stems and petioles 15 d after inoculation. The combination of bacterial antagonists could provide sustainable management of Fusarium wilt in banana under field conditions.