Confrontation between four fungal isolates and Phytophthora palmivora, on cocoa pod.

Abstract

Cocoa pod pericarp blocks (10×1x1cm) were challenge-inoculated with any one of four test antagonists (Trichoderma harzianum, Aspergillus fumigatus, A. niger and Rhizopus spp.) and phytophthora palmivora the causal organism of cocoa black pod disease. Results revealed that all the test antagonists were effective in checking the growth of the pathogen. All the test antagonists were able to colonize a good proportion of the cocoa pericarp which had previously been colonized by P. palmivora. However, none of the test antagonist was able to eliminate the pathogen completely from the inoculated pericarp. The test antagonist colonized the entire surface of the cocoa pod pericarp when inoculated before the pathogen and did not allow the pathogen to establish. Inoculation of intact matured green cocoa pods with aqueous suspension of the propagules of each of the test fungal antagonists did not produce any lesion. However, when a mixture of the pathogen with each of the test antagonist was used, lesions were produced.