dc.description.abstract |
Bacterial canker disease is one of the most economically destructive diseases of tomato (Solanum
lycopersicum) caused by gram positive bacterium, Clavibacter michiganensis Different disease
controlling mechanisms have been employed to tackle the problem. These days using plant extracts
is a new research focus area to reduce the side effect of chemical pesticides. The current study is
aimed to evaluate antibacterial potential of some medicinal plants against Clavibacter
michiganensis. The methanol and aqueous extracts of five medicinal plants namely Vernonia
amygdalina, Adhatoda shimperiana, Calpurnia aurea, Ricinus cummunis and Moringa oleifera
were evaluated in vitro using disc diffusion method. The fresh leaves of plants were dried at room
temperature under shade and ground to fine powder. Extraction was carried out using maceration
method and the phytochemical composition of extracts was analyzed qualitatively. Clavibacter
michiganensis was isolated using yeast dextrose calcium carbonate agar (YDC) medium from
infected tomato fruits collected and identified by colony morphology and pathogenicity test. The
higher extract yield was obtained from C. aurea (21.5%). Alkaloids, flavonoids, phenols, terpinoid,
saponin and tannins were found from the tested extracts. All the tested extracts showed antibacterial
activity against Clavibacter michiganensis with significantly different inhibition zone diameter. The
highest antibacterial activity and relative percentage inhibition was showed by extracts of R.
cummunis followed by V. amygdalina and Moringa oleifera in both solvent extracts. Extracts of R.
cummunis and V. amygdalina showed the lowest MIC value (3.15mg/ml and 6.25mg/ml
respectively). A. schimperiana and R. communis showed bactericidal effect against C.
michiganensis while M. oleifera and aqueous extract of V. amygdalina showed bacteriostatic effect.
The extracts of R. communis, V. amygdalina and M.oleifera could be candidates for further
development as biocides in the control of tomato canker disease. However, further studies should be
done to evaluate their performance under field conditions.
Key words: Aqueous extract, Clavibacter michiganensis, Inhibition zone, Medicinal plants,
Methanol extract, Tomato |
en_US |