Antifungal Activity of Annona muricata Seed Extracts Against Cercospora malayensis, Causal Agent of Cercospora Leaf Spot Disease of Okra (Abelmoschus esculentus L.)
Hubert Bolie
Department of Plant Biology, Faculty of Science, Laboratory of Phytopathology and Microbiology, Phytopathology and Plant Protection Research Unit, University of Yaounde I, P.O.Box 812, Yaounde, Cameroon.
Bekolo Ndongo
Department of Plant Biology, Faculty of Science, Laboratory of Phytopathology and Microbiology, Phytopathology and Plant Protection Research Unit, University of Yaounde I, P.O.Box 812, Yaounde, Cameroon.
Patrice Zemko Ngatsi
Department of Plant Biology, Faculty of Science, Laboratory of Phytopathology and Microbiology, Phytopathology and Plant Protection Research Unit, University of Yaounde I, P.O.Box 812, Yaounde, Cameroon.
William Norbert Tueguem Kuate
Department of Plant Biology, Faculty of Science, Laboratory of Phytopathology and Microbiology, Phytopathology and Plant Protection Research Unit, University of Yaounde I, P.O.Box 812, Yaounde, Cameroon.
Sylvere Landry Lontsi Dida
Department of Plant Biology, Faculty of Science, Laboratory of Phytopathology and Microbiology, Phytopathology and Plant Protection Research Unit, University of Yaounde I, P.O.Box 812, Yaounde, Cameroon.
Arnaud Essogue Etame
Department of Plant Biology, Faculty of Science, Laboratory of Phytopathology and Microbiology, Phytopathology and Plant Protection Research Unit, University of Yaounde I, P.O.Box 812, Yaounde, Cameroon.
Charles Salé Essomé
Department of Plant Biology, Faculty of Science, Laboratory of Phytopathology and Microbiology, Phytopathology and Plant Protection Research Unit, University of Yaounde I, P.O.Box 812, Yaounde, Cameroon.
Libert Brice Tonfack *
Department of Plant Biology, Faculty of Science,Laboratory of Biotechnology and Environment, Unit of Physiology and Plant Improvement, University of Yaounde I, P.O.Box 812, Yaounde, Cameroon.
*Author to whom correspondence should be addressed.
Abstract
Background: Cercospora leaf spot disease of okra whose pathogen is Cercospora malayensis causes yield losses of up to 60% in plantations. To limit productivity losses, fungicides are commonly used, but are expensive and degrade the environment.
Aims: This study aims to test in vitro efficacy of Annona muricata seed extracts against Cercospora malayensis.
Study Design: Four extracts were used in this study (the ethyl acetate, acetone, methanol and aqueous extract of A. muricata seeds at the concentrations C1 = 7.5 μl/ml, C2 = 15 μl/ml, C3 = 30 μl/ml and C4 = 60 μl/ml as well as the synthetic fungicide at the concentration of 3.33 g/l) in triplicate. The phytochemical screening of the extracts was performed, the radial growth of pure explants (7 mm diameter) of C. malayensis deposited in sterile Petri dishes containing the PDA medium supplemented with the different concentrations of extracts and incubated at 23 ± 1°C for 6 days were evaluated. Minimum inhibitory concentrations (MIC50, MIC90) were calculated.
Results: The extracts of A. muricata seeds are rich in tannins, flavonoids, terpenoids and phenols. The ethyl acetate extract at the concentration C3 resulted in 100% total inhibition of growth of C. malayensis in the Petri dishes. The other extracts resulted in total inhibition of the growth of C. malayensis at C4. The low MIC50 values (12.9 and 21 μl/ml) were obtained with the ethyl acetate and acetone extract, respectively. The ethyl acetate and aqueous extract at the C4 concentration were found to be fungicidal.
Conclusion: The extracts were found to be potential fungicide against the C. malayensis strain and might be an alternative in the fight against fungal diseases of okra as their activity was comparable to that of the synthetic fungicide Monchamp 72 WP.
Keywords: Cercosporamalayensis, extracts, extractsokra, antifungal, growth