Screening for Bioactivity of Phytochemical Extracted from Acacia stuhlmannii Against Ralstonia solanacearum

Abstract

Ralstonia solanacearum causes bacterial wilt in tomato and other important crops with significant losses in the Agriculture sector. Unfortunately this disease has no known cure to date. This study intended to screen crude extracts from Acacia stuhlmannii against this soil pathogen using disc diffusion techniques. Crude extracts were obtained from about 1 kg of powder by single solvent maceration with polar (ethanol) moderately polar (ethyl acetate) and non-polar (hexane) solvents that yielded 7.94, 4.90 and 3.27%, respectively. Disc diffusion tests were used to evaluate bioactivity of the phytochemical against Ralstonia solanacearum. Growth inhibition zones were measured in mm to reflect the bioactivity of extracts. Hexane extracts were the most potent fraction with bioactivity range of 13.1–23.8 mm compared to 11.4–19.1 mm and 10.3–10.8 for ethyl acetate and ethanol extracts, respectively. These findings therefore suggest that crude extracts from A. stuhlmannii root barks are a potential biocontrol agent in the management of Ralstonia solanacearum.

Keywords: Bioactivity, Acacia stuhlmannii, Ralstonia solanacearum