| Autor: |
Ndoungué Djeumekop MM; Laboratoire de Phytopathologie, Institute of Agricultural Research for Development (IRAD), BP 2123 Yaoundé, Cameroun.; Institut SupAgro, Unite Mixté de Recherche Biologie et Génétique des Interactions Plantes-Parasites (BGPI), Université Montpellier, F-34398 Montpellier, France., Ngo Bieng MA; Unite de Recherche Forêts et Sociétés, Centre de Coopération Internationale en Recherche Agronomique pour le Développement (CIRAD), Centro Agronómico Tropical de Investigación y Enseñanza (CATIE), 30501 Turrialba, Costa Rica.; Forêts et Sociétés, CIRAD, Université Montpellier, F-34398 Montpellier, France., Ribeyre F; Unite de Recherche Bioagresseurs, CIRAD, Université Montpellier, F-34398 Montpellier, France., Bonnot F; Unité Mixte de Recherche, BGPI, CIRAD, Université Montpellier, F-34398 Montpellier, France., Cilas C; Unite de Recherche Bioagresseurs, CIRAD, Université Montpellier, F-34398 Montpellier, France., Neema C; Institut SupAgro, Unite Mixté de Recherche Biologie et Génétique des Interactions Plantes-Parasites (BGPI), Université Montpellier, F-34398 Montpellier, France., Ten Hoopen GM; Laboratoire de Phytopathologie, Institute of Agricultural Research for Development (IRAD), BP 2123 Yaoundé, Cameroun.; Unite de Recherche Bioagresseurs, Cocoa Research Centre, CIRAD, The University of the West Indies, St. Augustine, Trinidad.; Bioagresseurs, CIRAD, Université Montpellier, F-34398 Montpellier, France. |
| Abstrakt: |
Studying spatial and temporal plant disease dynamics helps us 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's Exact test were used to analyze spatial and temporal disease dynamics. Disease distribution maps showed aggregated disease patterns in all plots; however, 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 to 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 unfavorable microclimatic conditions for disease development. Because 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 cacao black pod rot disease for newly established cacao plantations. |
