Spatial organisation influences citrus Pseudocercospora leaf and fruit spot disease severity in cocoa-based agroforestry systems

Ndo Eunice Golda Danièle, Akoutou Mvondo Etienne, Ambang Zachée, Manga Bella, Cilas Christian, Bidzanga Nomo Lucien, Gidoin Cynthia. 2019. Spatial organisation influences citrus Pseudocercospora leaf and fruit spot disease severity in cocoa-based agroforestry systems. American Journal of Plant Sciences, 10 : 221-235.

https://doi.org/10.4236/ajps.2019.101017

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Résumé : An investigation to assess the spatial structure and severity of Pseudocercospora leaf and fruit spot disease (PLFSD) on citrus trees in cocoa-based agroforests was carried out in three contrasting ecological zones in southern Cameroon, viz: 1) the humid forest zone, 2) the degraded forest zone, and 3) the forest-savannah transition zone. Two main parameters were investigated viz: 1) the spatial structure of cocoa based agroforests, and 2) the disease severity. In total, the spatial structure of 19 cocoa-based agroforests was analysed using the Ripley K(r) function, meanwhile the collection of epidemiological data that consisted of noting the presence of PLFSD spots on leaves and fruits on 438 citrus trees was used to characterise the severity of the disease. Results showed that, the spatial structure of citrus trees in these agroforests investigated were regular in seven plots, random in nine, and aggregated in three. Aggregated plots presented a significantly higher mean of disease severity on leaves and fruits (28.55 and 30.37 respectively), as compared to randomised (20.91 and 16.32 respectively) and regular plots (16.28 and 14.97 respectively), at P-value < 0.05. These results suggest that the spatial structure of citrus trees in the cocoa-based agroforests studied influences the severity of PFLSD. Proper integrated control measures can therefore be initiated, leading to a considerable reduction of the use of manufactured inputs, and thereby, the cost of production of citrus fruits.

Mots-clés Agrovoc : Pseudocercospora, Citrus, Theobroma cacao, agroforesterie, lutte intégrée antimaladie, agroécologie

Mots-clés géographiques Agrovoc : Cameroun

Mots-clés complémentaires : Pseudocercospora angolensis

Mots-clés libres : Aggregated Spatial Structure, Ripley Function, Agroecological Management of Disease, Pseudocercospora angolensis, Cocoa-Based Agroforests, Citrus

Classification Agris : H20 - Maladies des plantes
F08 - Systèmes et modes de culture
K01 - Foresterie - Considérations générales

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

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