Biorational phomopsis blight management in eggplants using two bacteria isolated from the eggplant rhizosphere

Abstract

Phomopsis blight, caused by Phomopsis vexans, is a major eggplant disease that significantly reduces output in Bangladesh. In order to produce a new fungicide, 210 bacterial strains were isolated from the rhizosphere of eggplants. Phylogenetic trees using 16S rRNA gene sequences of HSTUB 8 and HSTUB 16 revealed a close relationship with Serratia marcescens and Enterobacter ludwigii, respectively. Among the isolates, HSTUB 8 (Serratia marcescens) and HSTUB 16 (Enterobacter ludwigii) showed the maximum inhibition zones (1.6 cm and 0.9 cm, respectively) against P. vexans in vitro. In field conditions, basal application of pea bran-based formulated HSTUB 8 and HSTUB 16 followed by spraying of a suspension of both the bacteria exhibited a maximum reduction of disease incidence (64.70 %) and severity (77.27 %) over the control. The same bio-fungicide also resulted in enhanced growth and production, such as branches per plant (75.05 %), plant height (32.28 %), fruits/plant (404.54 %), firmness of fruits (57.42 %), and total soluble solids (66.67 %) over the control. Basal application of pea bran-based HSTUB 8 followed by spraying of the suspension of the same bacterium yielded a higher total phenol content in the fruits (56.86 mg/100 g) as compared to the control (24.74 mg/100 g). All gathered data strongly indicate that the pea bran-based formulated bio-fungicides composed of S. marcescens HSTUB 8 and E. ludwigii HSTUB 16 can be used for both the production of high-quality fruits and the management of phomopsis blight disease of eggplants at field conditions in an effective and eco-friendly way.