Influence of the position of detached cocoa pod inoculated with phytophthora palmivora on the development of lesion number and lesion size

Abstract

An experiment was conducted at the Cocoa Research Institute of Ghana (CRIG) to determine if there were any interactions between Phytophthora infection at the distal, proximal and mid-region positions of cocoa pods. The number and size of lesions in nine different cocoa clones were counted and measured at the three different positions of the pod. There were significant differences (p<0.001) among the clones in lesion numbers produced on the distal, proximal and mid-region positions of pods. It was also observed that significant differences (p<0.001) occurred among clones in the lesion sizes that developed on pod surfaces at the distal, proximal and midregions after inoculation with Phytophthora palmivora. There were highly significant interactions (p<0.001) among lesion sizes and lesion numbers produced on distal, proximal and mid-region positions of pods. Lesion number and lesion sizes on proximal position of pods were larger than lesion sizes and lesion numbers on the mid-region and distal positions of pods. This indicated that uniformity should be maintained by inoculating only at the most suitable position of pods during detached pod screening tests.

Keywords: Cocoa, Black pod, Phytophthora palmivora, lesions, clones