Antagonistic activities of Paecilomyces and Rhizopus species against the cocoa black pod pathogen (Phytophthora palmivora)

Two test fungal antagonists (Paecilomyces sp. and Rhizopus stolonifer) were isolated from cocoa rhizosphere and rhizoplane while the black pod pathogen (Phytophthora palmivora) was isolated from freshly infected cocoa pods. In vitro screening using the dual culture technique was conducted to assess their potential as biological control agents against the pathogen. The results revealed that in dual cultures, the test antagonists effectively checked the growth of P. palmivora. The antagonists grew faster than the pathogen and produced zones of inhibition. In liquid medium tests, the culture filtrates of the test fungi also inhibited the growth of P. palmivora. Rhizopus stolonifer was slightly more efficient (45%) than Paecilomyces sp.(43%) in inhibiting the growth of P. palmivora.