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Antimicrobial Activities of Indigenous Botanicals in the Control of Bacterial Soft Rot of Sweet Potato in Umuahia, Abia State, Nigeria

M. C. Ibeh
P. G. Uzoma
J. C. Agu


The antibacterial activities of aqueous and ethanol extracts of selected botanicals in the control of bacterial soft rot disease of sweet potato in Umuahia, Abia State, Nigeria were studied. Diseased sweet potato roots sourced from markets in Umuahia were taken to the laboratory to isolate and identify the causal organisms. Extracts of Vernonia amygdalina (Bitterleaf) and Bidens pilosa (Black jack) leaves and Syzygium aromaticum (Clove) seeds were tested in vitro against the bacterial isolates by Disk Diffusion Method in a Completely Randomized Design with three replications. The pathogenicity test revealed Erwinia spp (46.51%) and Bacillus (26.45%) to be pathogenic. Inhibition patterns differed with the plant extract, extraction solvent, and the organism tested. Vernonia amygdalina ethanolic extracts were the most active, against Erwinia spp (16.67mm), while B. pilosa ethanolic extracts highly inhibited Bacillus spp.(15.67mm). However, both were significantly different (P≤ 0.05) from aqueous Syzygium aromaticum extracts as it recorded the lowest inhibition of 8.67mm for Bacillus spp. and 9.67mm for Erwinia spp. All the botanicals were compared favourably with the standard antibiotic which had 21.67mm and 22.67mm against Erwinia and Bacillus pathogens respectively. Bitter leaf and Black Jack ethanol has shown significant potential in the pharmacognosy for the control of the isolated bacteria pathogens of sweet potato and is recommended for their control.