Foliar spraying with bacterial biocontrol agents for the control of common bacterial blight of bean

Abstract

The objective of this work was to evaluate the effect of foliar spraying with bacterial biocontrol agents (BBAs) on the control of common bacterial blight (CBB) of bean, and on the induction of systemic resistance in bean plants. CBB control by BBAs was evaluated by spraying bean leaves 48 and 24 hours before and after pathogen inoculation (BPI and API, respectively), with: DFs93, Bacillus cereus; DFs513, Pseudomonas veronii; DFs769, B. cereus; the C01 combination, DFs93 + DFs769 + DFs831 (Pseudomonas fluorescens); the C03 combination, DFs348 (Bacillus sp.) + DFs769 + DFs831; and water (control). Systemic effects were analyzed after spraying DFs513, DFs769, C03, and water 72 and 48 hours BPI. Phaseolin production induced by DFs348, DFs513, DFs769, DFs831, and water was also assessed. DFs513, DFs769, and C03 significantly reduced disease incidence (area under disease progress curve), regardless of spraying time and disease severity when sprayed 72 and 48 hours BPI. The DFs769 and DFs831 isolates induced the accumulation of phytoalexin (phaseolin). Therefore, DFs513, DFs769, and C03 show potential for the biocontrol of CBB when applied preventively on bean leaves, besides inducing systemic resistance.