Abstract

Citrus bacterial canker (CBC) threatens citrus fruit production in Burkina Faso due to the lack of effective control methods. In this study, the antimicrobial effect of copper hydroxide and sulphate, the biopesticide from Bacillus amyloliquefaciens, the essential oil of Ocimum gratissimum and aqueous extracts of Eucalyptus camadulensis, Azadirachta indica and Cymbopogon citratus were tested in vitro and in vivo against Xanthomonas cirri pv. citri (Hasse) (Xcc890) strain from Burkina Faso. The dilution method in solid medium and macro-method dilution in liquid medium were, respectively used in order to determine the minimum bactericidal concentration (MBC) and the minimum inhibitory concentration (MIC). Hydroxide and sulphate copper tested at 25 mg/ml induced 13 mm in diameter of inhibition zone, followed by B. amyloliquefaciens at 25 µl/ml (11.6±3.9 mm). O. gratissimum induced 10.5 ± 0.11 mm of inhibition zone at 5 µl/ml. Aqueous extract of E. camadulensis at 100 mg/ml induced 11.4 ± 1 mm of inhibition diameter. Based on MBC/MIC ratio, copper hydroxide and sulphate, O. gratissimum and E. camadulensis have a bactericidal effect in vitro. In vivo test, copper products at 25 mg/ml and O. gratissimum at 10 µl/ml were the most effective and significantly reduced the CBC incidence. These substances can be evaluated under natural conditions in order to determine their effectiveness against CBC.

Key words: Citrus species, citrus bacterial canker, Xanthomonas citri pv. citri, antibacterial activity, substances.