Impacts of Cu-Based Fungicide on Copper Residue and Mineral Elements Distribution in Cocoa Beans and Pods

Application of copper-based fungicide is still the most popular and effective means of controlling black pod disease among Nigerian cocoa farmers. There are two possible pathways through which copper gets into cocoa beans on the field: Uptake and translocation of Cu from soil and Permeation of cocoa pod cuticle by copper after fungicide application. Records showing quantitative contribution of applied fungicide to the total copper residue in cocoa beans are limited. A field study was carried out in 2009 and 2010 within Common Fund for Commodity (CFC) cocoa plot in Ibadan and Bodo cocoa plot in Ogun State, Nigeria. CFC plot had a hybrid (T65/7 X T15/9) cocoa on it while Bodo plot had F Amazon. Different concentrations of Cu solution 3 were applied on young cocoa pods (cherelles). At harvest, cocoa beans and pods were sun-dried and processed for chemical analysis according to standard procedure. In F Amazon, copper residue in cocoa beans 3 obtained from pods treated with the recommended rate (1.98 g/L) was significantly (P < 0.05) higher than the Cu residues in control (untreated) and those treated with 3.96 g and 5.94 g Cu/L. In T65/7 X T15/9, copper in beans from pods treated with various rates were significantly (P < 0.05) higher than Copper residue in the control beans. The study shows that, the recommended rate (1.98 g Cu/L) increased Cu residue in cocoa beans by 11.19 and 12.24% in T65/7 X T15/9 and F Amazon respectively, relative to the control beans. It also shows 3 that, Cu fungicides applied on cocoa pods contribute to the total Cu residue in cocoa beans.