Spatial and temporal analysis of Phytophthora megakarya epidemic in newly established cacao plantations

Ndoungue Djeumekop Minette Mireille, Ngo Bieng Marie-Ange, Ribeyre Fabienne, Bonnot François, Cilas Christian, Neema Claire, Ten Hoopen Gerben Martijn. 2021. Spatial and temporal analysis of Phytophthora megakarya epidemic in newly established cacao plantations. Plant Disease, 13 p.

Journal article ; Article de recherche ; Article de revue à facteur d'impact
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Abstract : Studying spatial and temporal plant disease dynamics helps to understand pathogen dispersal processes and improve disease control recommendations. In this study, three cacao plots devoid of primary inoculum of Phytophthora megakarya (causal agent of cacao black pod rot disease) upon establishment in 2006 were monitored for presence of disease on a weekly basis from 2009 to 2016. Ripley's K(r) function, join count statistics and Fisher Exact test were used to analyse spatial and temporal disease dynamics. Disease distribution maps showed aggregated disease patterns in all plots although for the years of disease onset, exogenous primary infections were mostly randomly distributed. The K(r) function confirmed these results indicating that inoculum generally disperses only over short distances. Moreover, significant positive spatial autocorrelations showed that diseased trees were often clustered up to a distance of 3-9 m. Temporal disease progression was low, meaning that endogenous inoculum failed to establish itself which is partly explained by rigorous phytosanitation and partly by unfavourable microclimatic conditions for disease development. Since P. megakarya had difficulty establishing itself in the plots, proximity to already infected cacao plantations drove infection dynamics. Thus, isolation of newly established cacao plantations from infected ones and rigorous phytosanitation as a preventive strategy appears to be an effective approach to control black pod for newly established cacao plantations.

Mots-clés Agrovoc : Maladie des plantes, Theobroma cacao, Phytophthora, analyse spatiale, épidémie, Modélisation, Plantations

Mots-clés géographiques Agrovoc : Cameroun

Mots-clés complémentaires : Phytophthora megakarya, analyse temporelle, Pourriture des cabosses, Pourriture brune

Mots-clés libres : Theobroma cacao, Phytophthora megakarya, Black pod, Spatial analysis, Temporal dynamics

Classification Agris : H20 - Plant diseases
U10 - Computer science, mathematics and statistics

Champ stratégique Cirad : CTS 4 (2019-) - Santé des plantes, des animaux et des écosystèmes

Auteurs et affiliations

  • Ndoungue Djeumekop Minette Mireille, IRAD (CMR) - auteur correspondant
  • Ngo Bieng Marie-Ange, CIRAD-ES-UPR Forêts et sociétés (CRI)
  • Ribeyre Fabienne, CIRAD-BIOS-UPR Bioagresseurs (FRA)
  • Bonnot François, CIRAD-BIOS-UMR BGPI (FRA)
  • Cilas Christian, CIRAD-BIOS-UPR Bioagresseurs (FRA)
  • Neema Claire, Montpellier SupAgro (FRA)
  • Ten Hoopen Gerben Martijn, CIRAD-BIOS-UPR Bioagresseurs (FRA) ORCID: 0000-0003-2133-3130

Source : Cirad-Agritrop (

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