Journal of Applied Biosciences (J. Appl. Biosci.) [ISSN 1997 - 5902]

Volume 77: 6564 - 6574  Published May  31, 2014.

Effect of extracts of Thevetia peruviana (Pers.) K.Schum on development of Phytophthora megakarya causal agent of black pod disease of cocoa .

Jules Patrice NGOH DOOH1,2*; Zachee AMBANG1; NDONGO BEKOLO1 ; Alain HEU1.; William KUATE TUEGUEM1.
1-Laboratory of Plant Pathology, Department of Plant Biology, Faculty of Science, University of Yaoundé I (Cameroon), BP 812
2-Department of Biology, Faculty of Science, University of Maroua (Cameroon), BP 46 Maroua
1*Corresponding author: ndjuliopat@yahoo.fr ; tel:99219391;

Original submitted in on 12th March 2014. Published online at www.m.elewa.org on 31st May 2014. http://dx.doi.org/10.4314/jab.v77i1.11

ABSTRACT
Objective: The in vitro and in vivo effects of seed extracts of Thevetia peruviana (Apocynaceae) on the growth and the germination of spores of Phytophthora megakarya causal agent of black pod of cocoa was evaluated .
Methodology and results: Five extracts obtained by soxhlet apparatus (extracts of hexane, ethyl acetate, acetone, methanol and aqueous extract) were used. One fungicide (Ridomil ® gold plus) served as control reference. Five strains of P. megakarya (Mbal 121, Ngoke 111, Nom121, Mbal 212, njo111) were tested. Three concentrations of extracts (6.25, 12.5 and 25 µl/ml) and one concentration of fungicide were used in V8 medium. Detached fruit bioassay was performed. Spores of five strains of P. megakarya were inhibited by methanolic and acetonic extracts of T. peruviana with an inhibition percentage ranging from 99-100 %. Thus, the smallest concentration of extract is capable of acting on the germination of spores of the fungi. Only hexane extract did not inhibit the growth of strains. Methanol extract reduced the growth from 60 to 100% at 25 µl/ml. The detached fruits bioassays demonstrated the effectiveness of extracts on plant tissue when inoculated with P. megakarya zoospores.
Conclusion and application of findings: Statistical analysis shows that methanol and acetone extracts are as effective as the tested fungicide on the growth and germination of zoospores, aqueous extract are effective as Ridomil ®  on growth on the black pod disease of cocoa. These extracts could be used in the integrated pest management strategy of the plant pathogens tested.
Key words. Phytophthora megakarya, Thevetia peruviana, extract, biocontrol, black pod disease.

FULL PAPER [PDF AVAILABLE HERE]