Integration of Pseudomonas fluorescens and Rosemarinus officinalis for controlling of potato bacterial wilt

Abstract

Background Bacterial wilt caused by Ralstonia solanacearum is considered one of the most important diseases that cause economic losses to many economic crops and spread in many regions around the world, especially in the subtropical tropics and some warm temperate regions of the world. In this study the aqueous plant extract of Rosemarinus officinalis and Pseudomonas fluorescens for their antagonistic activity against bacterial wilt in vitro, greenhouse and population of R, solanacearum in plants was study. Results Following intensive screening studies, aqueous plant extract of R. officinalis and P. fluorescens was selected to study their effectiveness against bacterial wilt of potato plants and their antimicrobial activity or induction of systemic resistance in plants. In greenhouse, all soil drenching treatments on potato plants significantly reduced disease incidence of potato bacterial wilt than infected control. R. officinalis, P. fluorescens mixture between plant extract and endophytic bacteria and streptomycin reduced profoundly the disease severity by 75.51, 65.0 77.9 and 81.00%, respectively, than the infected control (83.71%). The plant extract and microorganism significantly increased fresh and dry weight of potato plants (g) per plant compared to non-treated control plants. R. officinalis, P. fluorescens mixture between plant extract and endophytic bacterium and streptomycin increased fresh weight from 100.1 to 169.9 compared to infected control also increased dry weight from 68.4 in streptomycin to 170.4% in mixture of plant extract and endophytic bacterium. The populations of bacterial pathogen R. solanacearum were lowest in stem of potato plants treated with plant extracts than in inoculated control plants (50%). In general, the total phenols increased in both inoculated and non-inoculated potato plants. Conclusions Ralstonia officinalis and P. fluorescens showed a strong in vitro activity in relation growth limitation of R. solanacearum as well as limiting the development of bacterial wilt disease on potato plants under greenhouse conditions.