FOLIAR RESISTANCE TO PHYTOPHTHORA-PALMIVORA AS AN INDICATOR OF POD RESISTANCE IN THEOBROMA-CACAO

Resistance to Phytophthora palmivora was assessed in leaves and pods o f 12 diverse cacao genotypes at the penetration and post-penetration s tages of infection to determine the relationship of resistance between stages and sites of infection. Penetration resistance was based on th e frequency of lesions, whereas lesion size was used as a measure of p ost-penetration resistance. We observed significant clonal differences for leaf and pod resistance at the two stages of infection. A poor co rrelation between resistance at the penetration and post-penetration s tages in both leaves and pods indicated that these two forms of resist ance are independent and governed by different mechanisms. Correlation between resistance of leaves and pods was not significant at the pene tration stage, whereas that of post-penetration resistance was positiv e and significant. This shows that internal or tissue resistance is co mmon between leaf and pod and indicates that leaf resistance at the po st-penetration stage of infection could be used to predict pod resista nce; however, resistance of leaves at the penetration stage cannot be used to predict penetration resistance in pods. A high positive correl ation obtained between attached leaves and pods with their detached co unterparts showed that detached organs can be used for the prediction of resistance in attached leaves and pods.