Black pod disease caused by P. Palmivora and P. megakarya is an important disease affecting cacao in West Africa which produces 70% of the world output. Resistance to the pathogen is therefore, an important factor to be considered when breeding for high yielding and earliness in fruiting. Resistance to the pathogen using Leaf Disc Test (LDT) was conducted at the Plant Pathology Laboratory, Ibadan, on detached 15mm diameter discs of two-month-old leaves obtained from nineteen newly generated cacao hybrids in the gene pool of the Institute. Attached Whole Leaf Test (AWLT) was also conducted on few selected hybrids in the screen house at the same institute. Ten µl zoospores suspension of P. megakarya pathogen adjusted to inoculum strength of 3x10 5 zoospores/ml using haemocytometer was used for the inoculation of the cacao LD. Using 0-5 disease rating scale, data was taken on the 5 th and 7 th day after inoculation for LDT and on the 6 th day after inoculation for AWLT. Data obtained were subjected to Analysis of Variance and significant means were separated using Student Newman Kuels Test at p<0.05. The LDT classified the hybrids into five groups namely: Resistant (hybrid 001, 003 and 005); Moderately Resistant (hybrid 006, 007, 008,013,015,018 and 019) Moderately Susceptible (hybrid 004, 014 and 017); Susceptible (hybrid 002, 010, 011 and 016) and Highly Susceptible (hybrid 009 and 012). Scores from LDT significantly correlated (r= 0.92**) with that of AWLT. It was observed from the study that cacao hybrid 001, 003 and 005 showed traits of resistant and therefore, could be incorporated into the national breeding programs for the development of high-yielding and resistant cacao cultivars. The moderately resistant hybrids could be conserved for future germplasm enhancement program.

中文翻译：

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测试尼日利亚可可研究所（CRIN）基因库中新生成的杂交可可种质对引起可可黑荚病的疫霉菌（Phytophthora megakarya）病原体的抗性。

由P. Palmivora和P. megakarya引起的黑荚病是影响西非可可的重要疾病，占世界产量的70％。因此，对病原体的抗性是为高产和早产而进行育种时要考虑的重要因素。在伊巴丹州植物病理实验室，使用叶片圆盘试验（LDT）对病原体产生了抗药性，该研究所从研究所基因库中的十九个新近产生的可可杂种中获得了两个月龄叶片的直径15毫米的分离圆盘。在同一研究所的筛选室中，还对少数几个杂种进行了附着全叶试验（AWLT）。用血细胞计数器将10μl巨核疟原虫病原体悬浮液的接种强度调整为3x10 5游动孢子/ ml，用于接种可可菌。使用0-5疾病等级量表，在接种LDT后第5天和第7天以及接种AWLT后第6天获取数据。对获得的数据进行方差分析，并使用Student Newman Kuels检验在p <0.05时分离显着的均值。LDT将杂种分为五类：抗性（杂种001、003和005）；中度耐性（混合006、007、008,013,015,018和019）中度易感（混合004、014和017）; 易感（混合002、010、011和016）和高度易感（混合009和012）。LDT的分数与AWLT的分数显着相关（r = 0.92 **）。从研究中发现，可可杂种001、003和005表现出抗性，因此，可以纳入国家育种计划，以开发高产和抗性的可可品种。具有中等抗性的杂种可以被保留以用于将来的种质增强计划。