Enquête diagnostic sur la maladie des taches noires de l'ananas à la Martinique : Problématique et méthodologie

En Martinique la maladie des taches noires constitue le problème majeur de la production intensive de l'ananas, occasionnant en moyenne 10 % de perte par an. Si l'on possède des renseignements sur la nature des agents causaux, les mécanismes d'infection et la symptomatologie, en revanche l'étiologie exacte de cette maladie soumise à l'influence de très nombreux facteurs (populations des agents pathogènes et des vecteurs, conditions climatiques, pratiques culturales) reste peu connue. Afin d'identifier et de hiérarchiser ces facteurs dans les conditions martiniquaises une enquête diagnostic a été initiée. Le principe de l'enquête repose sur l'observation d'un nombre important d'unités élémentaires représentatives de la plus grande variabilité possible. L'analyse d'environ 120 parcelles (3 dates de plantations concernant chacune environ 40 parcelles) permettra d'étudier la variabilité temporelle et spatiale dans l'expression de la maladie et de dégager les principaux facteurs explicatifs. Ainsi l'enquête diagnostic a pour objectif essentiel, outre une meilleure connaissance de la maladie, la proposition de solutions techniques concrètes, notamment en terme de pratiques culturales, visant à réduire l'impact de cette maladie. ----- In Martinique the black spot disease is the main problem for intensive pineapple cultivation as it results in average losses of 10%. Although the nature of the causal agents, the infection mechanisms and the symptomatology are known to some extent, the etiology of the disease, the expression of which depends on many factors (populations of pathogens and vectors, climatic conditions, cultural practices), is poorly documented. To identify and hierarchize these factors in the context of Martinique, a diagnostic survey was initiated. This method consists in sampling a high number of elementary observation units to represent the widest variability of situations. Practically, the analysis of 120 observation units (about 40 plots observed at 3 planting dates) will allow to study spatial and temporal variability in the expression of the disease and to identify the most significant factors. So, the main objectives of the diagnostic survey are not only a better understanding of the disease but also the proposai of technical solutions (cultural practices) to reduce the impact of the disease

Effects of Xanthomonas wilt and other banana diseases on ecosystem services in banana-based agroecosystems

Banana plantations are multifunctional agroecosystems that besides their main provisioning service also deliver a range of supporting, regulatory and cultural services that are largely unvalorized. Banana is perennial in nature with plantations as old as 50 years reported in the African Great Lakes region. Banana is cultivated in a wide range of agroecologies (from sea level to 2400 m a.s.l.) and cropping systems, where it contributes to various ecosystem services (ES). These include regulating soil erosion, water cycles and quality, and nutrient recycling. However, the outbreak of Xanthomonas wilt of banana (XW) along with some of its management practices, such as uprooting mats/entire fields, is devastating banana production and rendering landscapes bare and prone to degradation. Yet this process is also leading to diversification of agroecosystems in over 70% of farms in the African Great Lakes region with unknown but potentially positive consequences for resilience and adaptation, as well as for local diets. The sustainability of these alternative land-uses is variable. This study reviews the different services offered by banana plantations and the impacts, positive or negative, that XW-driven diversification may have on these services. It suggests the need to consider explicitly the consequences of pests and diseases for the full range of ES provided by the crop and an ES-broad framework for estimation of losses, and planning resources and strategies for disease management. The study also suggests strategies, such as incorporation of shade- and drought-tolerant cover crops, hedges and agroforestry trees, to augment the supply of key ES within XW-affected agroecosystems/landscapes

Agroecological integration of shade- and drought-tolerant food/feed crops for year-round productivity in banana-based systems under rain-fed conditions in Central Africa

Yield gaps in banana-based production systems have increased in the past two decades due to declining soil fertility, drought and biotic stresses. Sustainable, environmentally sound and economically viable strategies for intensification in these systems are urgently needed. Agroecological practices, such as the integration of shade- and drought-tolerant crops, nitrogen-fixing and cover crops could potentially improve soil fertility and moisture retention, reduce the weed burden, narrow yield gaps and increase overall plot/farm productivity in these systems. In Malaysia, leguminous crops like Pueraria phaseoloides, Calopogonium caeruleum and Centrosema pubescens are often cultivated as cover crops (to suppress weeds, and reduce moisture loss and soil erosion) in young rubber and oil palm plantations with low shade levels. Even in mature oil palm plantations with less than 30% light intensity, various shade-tolerant crops are grown, e.g., elephant foot yam, turmeric and arrow root. In humid tropical Africa, Colocasia (taro) and Xanthosoma (cocoyam) are reported to tolerate shade conditions and hence often planted under perennial banana/plantain plantations. Drought tolerance is a less common feature of most annual crops grown in the humid tropics. A few root and tuber crops (e.g., cassava, taro, yam and sweetpotato) remain in the field during the dry season in Central Africa and are then harvested according to household needs. This paper also reports on crops (Mucuna, lablab and chickpea) with potential for integration into banana-based systems during the dry season, if planted during the last month of the rainy season. These crops are reported to use the residual soil moisture content for continued growth during the dry season months. The paper concludes with detailed descriptions (from a literature review) on drought- and shade-tolerance characteristics of various crops which have long been integrated in Central African banana-based cropping systems, crops with a more recent cultivation history and crops with potential for system integration

Agroecological transformation for sustainable food systems : Insight on France-CGIAR research

This 26th dossier d’Agropolis is devoted to research and partnerships in agroecology. The French Commission for International Agricultural Research (CRAI) and Agropolis International, on behalf of CIRAD, INRAE and IRD and in partnership with CGIAR, has produced this new issue in the ‘Les dossiers d’Agropolis international’ series devoted to agroecology. This publication has been produced within the framework of the Action Plan signed by CGIAR and the French government on February 4th 2021 to strengthen French collaboration with CGIAR, where agroecology is highlighted as one of the three key priorities (alongside climate change, nutrition and food systems)