Evaluation Of The Medicinal Plant(Parthenium Hysterophorus) For The Management Of Bacterial Wilt Of Tomato

Heavy damage to tomato crops due to wilt stress caused by pathogenic bacterium Ralstonia solanacearum and insufficient availability of management strategies with desired control level urged the researchers to investigate more reliable control methods to manage this issue in tomato and other horticultural crops.In this study,we investigated the in vitro antibacterial activity and action mechanism of indigenous and freely available medicinal plants against the bacterial wilt pathogen,R.solanacearum.The extracts were obtained from seven plants in the study area using ethanol solvent.The well diffusion method and microdilution assays were used to evaluate the antibacterial activity,while SEM analysis was used to analyze the morphological changes in bacterial cells.The study found that among various plants,the extract of Parthenium hysterophorus exhibited highest antibacterial activity against R.solanacearum.The antibacterial activity of P.hysterophorus was concentration-dependent which greatly affected the cell viability,swarming ability and biofilm formation ability of R.solanacearum.Moreover,the extracts caused significant destructive changes in the morphology of R.solanacearum as evident by scanning electron microscopic analysis.These findings suggest that the tested medicinal plant may have potential as natural antimicrobial agents against R.solanacearum,which can be useful in the management of bacterial wilt disease in crops.In our second experiment we tested the potential of P.hysterophorus extract to manage bacterial wilt disease in tomato plants under green house and field conditions through its powder application to soil.Different application methods(mixing and mulching)and times(0,5,10,and 15 days before transplantation)were evaluated.First the phytotoxicity of the P.hysterophorus powder to tomato plants at different doses was determined to find out the maximum safe application dose.The results showed that P.hysterophorus powder at amount higher than 25g/Kg soil caused phytotoxicity to tomato plants.So,the 25g/Kg soil dose was evaluated against bacterial wilt disease under green house and field conditions.In both greenhouse and field trails,soil amended with P.hysterophorus powder at 25g/Kg soil was found to effectively suppressed the pathogen population in soil and significantly reduced the wilt severity on tomato plants which resulted in increased plant growth and yield.Results showed that P.hysterophorus powder applied through mixing of soil at longer duration before transplanting tomato plants was more effective than mulching application and at shorter duration of transplantation.Findings of this study revealed the efficacy and action mechanism of P.hysterophorus powder application to soil for the management of bacterial wilting stress in tomato plants and provide basis for including this technique as safe and effective management strategy to integrated disease management package.P.hysterophorus plant extract that showed strong antibacterial activity against R.solanacearum and successfully utilized for the management of tomato bacterial wilt disease in previous experiments was further investigated against 12 plant pathogenic fungi and root knot nematodes.The antifungal ability of the plant extract in different concentrations was checked through food poisoning technique against 12 fungal plant pathogen.The nematicidal activity was checked through juvenile mortality and egg hatch inhibition test.Results showed that the plant extract did not show considerable nematicidal activity against any nematode.The maximum J2 s mortality and egg hatch inhibition was less than 29.45% and 26.34%,for M.incognita and M.javanica,respectively.Regarding antifungal activity,the plant extract showed significant antifungal activity against only Fusarium spp.The highest concentration of the extract caused74.32% and 71.28% growth inhibition of F.proliferatum,F.oxysporum,respectively.Findings of this study suggested that the plant extract possess selected antifungal activity against some plant pathogens and can be used as ecofriendly management of plant diseases.