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<p>Black pod rot caused by <i>Phytophthora</i> species is one of the most destructive diseases limiting cocoa production. During August to December 2023, typical black pod rot symptoms were observed on cocoa pods in Avidi village (Konaseema district), Andhra Pradesh, India. The disease initiated as small chocolate-brown lesions which enlarged rapidly, turning pods completely black and mummified. The pathogen was isolated from infected pod tissues on carrot agar medium and purified through single spore isolation. Morphological examination revealed papillate sporangia and chlamydospore formation, indicating <i>Phytophthora palmivora</i>. Pathogenicity was confirmed by agar disc inoculation on cocoa pods, producing typical lesions within 24&#xa0;h, and the pathogen was re-isolated, fulfilling Koch’s postulates. Molecular confirmation was obtained by amplification and sequencing of ITS, COX-II and β-tubulin gene regions. BLAST analysis and phylogenetic clustering confirmed the pathogen identity as <i>P. palmivora</i>. Representative sequences were deposited in GenBank under accession number OR917912. This study confirms <i>P. palmivora</i> as the predominant causal agent of cocoa black pod rot in Andhra Pradesh.</p>

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Molecular characterization of Phytophthora palmivora associated with black pod rot disease of cocoa in Andhra Pradesh, India

  • 期刊论文

  • 发表日期：

    2026年6月15日

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  • B. Neeraja,
  • V. Prasanna Kumari,
  • K. Gopal,
  • N. B. V. Chalapathi Rao

摘要

Black pod rot caused by Phytophthora species is one of the most destructive diseases limiting cocoa production. During August to December 2023, typical black pod rot symptoms were observed on cocoa pods in Avidi village (Konaseema district), Andhra Pradesh, India. The disease initiated as small chocolate-brown lesions which enlarged rapidly, turning pods completely black and mummified. The pathogen was isolated from infected pod tissues on carrot agar medium and purified through single spore isolation. Morphological examination revealed papillate sporangia and chlamydospore formation, indicating Phytophthora palmivora. Pathogenicity was confirmed by agar disc inoculation on cocoa pods, producing typical lesions within 24 h, and the pathogen was re-isolated, fulfilling Koch’s postulates. Molecular confirmation was obtained by amplification and sequencing of ITS, COX-II and β-tubulin gene regions. BLAST analysis and phylogenetic clustering confirmed the pathogen identity as P. palmivora. Representative sequences were deposited in GenBank under accession number OR917912. This study confirms P. palmivora as the predominant causal agent of cocoa black pod rot in Andhra Pradesh.