Studies on Penicillium digitatum, Botryodiploidia theobromae, Alternaria tenuis and Trichoderma harzianum for Bicontrol of Phytophthora palmivora Cocoa Black Pod Disease Pathogen
In vitro studies on biological control of Phytophthora palmivora cocoa black pod disease pathogen by Penicillium digitatum, Botryodiploidia theobromae, Alternaria tenuis and Trichoderma harzianum were carried out using dual culture technique. The percentage inhibition of radial growth of the pathogen was assessed and the width of the zone of inhibition was measured. All data were analysed using analysis of variance and Duncan Multiple range test. The results revealed a significant difference (P<0.05) in radial growth of pathogen when in dual culture with tested fungi and when it was alone. P. digitatum and Trichoderma harzianum grew faster, effectively checked the growth of P. palmivora and produced zones of inhibition. B. theobromae and Alternaria tenuis did not show enough potential. The inhibitory effect of the culture filtrates of potential antagonists on pathogen was significant (P < 0.05) and mostly began on day 5 and increased with age of incubation. Trichoderma harzianum and P. digitatum were observed to be effective at checking the growth of P. palmivora in both solid and liquid media and therefore showed the potentials for the biological control of the pathogen. while A. tenuis and B. theobromae did not show enough potential under the conditions of this study.