Pests and diseases are major determinants of cocoa yield, but continuous synthetic chemical control of cocoa pests contributes to environmental pollution and high production costs. As an alternative, we assessed the influence of eight commonly retained forest tree species on mirid and black pod disease infestation, compared to unshaded portions in 10 cocoa fields in the Western region of Ghana. The influence of tree species, on-farm temperature, rainfall, and relative air humidity was assessed on mirid population densities on cocoa trees, and mirid and black pod disease infested pods from May 2018 to December 2020. Shade tree species had significant effects on mirid densities and resulting pod damages, with highest mirid occurrence in K. Schum (0.51 ± 0.12 mirids tree yr) and lowest occurrence in A. Chem (0.21 ± 0.07 mirids tree yr), L. (0.22 ± 0.09 mirids tree yr) and (Welw.) C. Berg. (0.24 ± 0.09 mirids tree yr) plots, compared to the unshaded control plots (0.48 ± 0.12 mirids tree yr). Black pod disease (caused by spp.) infection was significantly different among species with highest pod damage observed around Schott and Endl. and least in unshaded areas. The occurrence of black pod disease varied with seasons and correlated with monthly rainfall and humidity, while mirid infestation correlated with monthly temperature. The diameter of shade trees and the density of cocoa trees influenced both mirid infestation and black pod disease infection. Hence, careful selection of shade tree species appears to be an important strategy to enhance integrated pest management (IPM) in cocoa systems.

中文翻译：

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选定的遮荫树种在控制加纳可可农林系统中的黑豆和黑荚病感染方面的潜力


病虫害是可可产量的主要决定因素，但对可可害虫的持续合成化学防治会造成环境污染和高昂的生产成本。作为替代方案，我们评估了八种普遍保留的森林树种对黑荚果病和黑荚病侵染的影响，并与加纳西部地区 10 个可可田的无遮荫部分进行了比较。 2018年5月至2020年12月期间，评估了树种、农场温度、降雨量和相对空气湿度对可可树黑豆种群密度以及黑豆荚病和黑豆病侵染的豆荚的影响。遮荫树种对黑豆数量有显着影响。密度和由此产生的荚果损害，其中 K. Schum 中的螟发生率最高（0.51 ± 0.12 螟树年），A. Chem 的发生率最低（0.21 ± 0.07 螟树年）、L.（0.22 ± 0.09 螟树年）和（好吧。）C.伯格。 （0.24 ± 0.09 鸢尾树年）图，与无阴影对照地块（0.48 ± 0.12 鸢尾树年）相比。黑豆荚病（由某些物种引起）感染在 Schott 和 Endl 周围观察到的豆荚损害最高的物种之间存在显着差异。至少在无阴影区域。黑豆荚病的发生随季节变化，与每月降雨量和湿度相关，而黑豆荚病的发生与每月温度相关。遮荫树的直径和可可树的密度对黑豆侵染和黑豆荚病感染都有影响。因此，仔细选择遮荫树种似乎是加强可可系统害虫综合防治（IPM）的重要策略。