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Crop disease often leads to field epidemics with serious threats to yield. Early symptoms are sometimes difficult to identify, so the origin of primary inoculum is a critical focal point in the study of plant diseases, as it can help design management strategies to reduce crop losses. Here, we investigated whether anthracnose of water yams (Dioscorea alata L.) caused by the species complex Colletotrichum gloeosporioides can start from infected seed tubers from the previous harvest. Over two years, we collected tubers with varying pathogen prevalence in the field directly from producers and conducted fungal isolations in the lab to sample C. gloeosporioides. We also proceeded to artificially inoculate tubers before planting and monitored disease development. Finally, we genotyped isolates from leaves in the fields and assessed fixation indices between plots based on plot ownership (plots with a common seed tuber origin from a single farmer) vs. samples in plots from unrelated producers in Guadeloupe, Martinique, and Barbados. We were unable to isolate the fungus from harvested tubers in either sampling survey nor did any plants grown from inoculated tubers develop any disease symptoms during growth. Also, the genetic structure of samples within each plot was independent of plot ownership, though this occurred with varying levels in the different islands. These results suggest that contaminated planting material from seed tubers is not the primary source of the disease, which is in contrast to the common perception of yam anthracnose prevalence in the Antilles. [ABSTRACT FROM AUTHOR]

In context of global challenges facing agriculture, our article addresses the extent to which the synergistic nature of agroecological innovations may reconcile environmental and technical efficiency of farms. We develop an empirical model, namely conditional efficiency framework, which explicitly accounts for context-dependent drivers like synergy and complementarity of innovations. Using a sample of 567 banana farms in the French West Indies, our estimates confirm the complementarity effect since the joint adoption of agroecological innovations increases the technical efficiency scores much more than other drivers and each of the innovations taken in isolation. We also show that advice and extension services as well as human capital variables are key adoption levers for public policy since they reduce the variability of production and thus the risk associated with the joint adoption of the agroecological innovations. [ABSTRACT FROM AUTHOR]

Colletotrichum gloeosporioides is a species complex of agricultural importance as it causes anthracnose disease on many crop species worldwide, and strong impact regionally on Water Yam (Dioscorea alata) in the Caribbean. In this study, we conducted a genetic analysis of the fungi complex in three islands of the Lesser Antilles—Guadeloupe (Basse Terre, Grande Terre and Marie Galante), Martinique and Barbados. We specifically sampled yam fields and assessed the genetic diversity of strains with four microsatellite markers. We found a very high genetic diversity of all strains on each island, and intermediate to strong levels of genetic structure between islands. Migration rates were quite diverse either within (local dispersal) or between islands (long-distance dispersal), suggesting important roles of vegetation and climate as local barriers, and winds as an important factor in long-distance migration. Three distinct genetic clusters highlighted different species entities, though there was also evidence of frequent intermediates between two clusters, suggesting recurrent recombination between putative species. Together, these results demonstrated asymmetries in gene flow both between islands and clusters, and suggested the need for new approaches to anthracnose disease risk control at a regional level. [ABSTRACT FROM AUTHOR]

Conceptualized by the Food and Agriculture Organization in 2010, climate-smart agriculture aims to simultaneously tackle three main objectives. These are increasing food security, building the resilience of agricultural systems for adaptation to climate change and mitigation of GHG. As much research focuses on one of these three objectives, our understanding of how agricultural systems address these three challenges simultaneously is limited by the lack of a comprehensive evaluation tool. In order to fill this gap, we have developed a generic evaluation framework that comprises 19 indicators that we measured in a sample of 12 representative farms of the North Basse-Terre region in Guadeloupe. The evaluation revealed clear differences in the performance of these farming systems. For example, nutritional performance varied from 0 to 13 people fed per hectare, the average potential impact of climatic conditions varied from 27% to 33% and the GHG emissions balance varied from +0.8 tCO2eq·ha−1 to +3.6 tCO2eq·ha−1. The results obtained can guide the design of innovative production systems that better meet the objectives of climate-smart agriculture for the study region. The evaluation framework is intended as a generic tool for a common evaluation basis across regions at a larger scale. Future prospects are its application and validation in different contexts. [ABSTRACT FROM AUTHOR]

Developing climate-smart agriculture is an urgent necessity to ensure the food security of a growing global population, to improve the adaptation of agricultural systems to climatic hazards, and to reach a negative carbon balance. Different approaches are being explored to achieve those objectives, including the development of new technologies for efficiency improvements to current systems and substitution of chemical inputs by bio-inputs, but the urgency of the climatic, social, and environmental context calls for more disruptive actions to be taken. We propose an approach to the design of climate-smart production systems structured in four steps: (1) diagnosis of the study region on the basis of the three pillars of climate-smart agriculture, (2) co-design of a disruptive system only based on agroecological and bioeconomic principles, (3) long-term experimentation of this system, and (4) in itinere adjustment of the system based on collected data and on-field evaluations with agricultural stakeholders. The outcome of this approach is the agroecological microfarm named KARUSMART, settled in 2018 on one hectare in the North Basse-Terre region of Guadeloupe (F.W.I.). This study presents its co-design and experimentation stages as well as the first performance results. At the end of the first two years, this microfarm showed a clear improvement in 15 of the 19 indicators used to evaluate the performance of the actual farming systems in the study region. Among the most striking results are a clear superiority in nutritional performance from 3 pers.ha−1 to 8 pers.ha−1 and a reduction in GHG balance from +2.4 tCO2eq.ha−1 to −1.1 tCO2eq.ha−1 for the study area and the microfarm, respectively. These results are promising for developing climate-smart agricultural systems and need to be consolidated further through longer-term monitoring data, the implementation of more similar systems in the study area, and the implementation of the design principles in other contexts. [ABSTRACT FROM AUTHOR]

To improve agriculture faced with regional sustainability issues, agricultural landscapes providing a diversity and high level of ecosystem services are necessary. We have developed and tested the MOSAICA-f framework to build innovative multi-functional agricultural landscapes that can consider explicitly: 1) the performance of cropping systems at the field scale, 2) farmers' decision processes on the adoption of cropping systems, and 3) possible scenarios for innovations and policy changes at the regional scale. This framework is based on a scenario approach that encompasses normative, exploratory and optimized scenarios to assess the relevance of combinations of new agricultural policies, changes to the external context (market and regulations) and innovations in cropping systems. The impacts of these changes on sustainability issues are simulated using the regional bioeconomic model MOSAICA for farmers' decision processes regarding the adoption of cropping systems at the field scale throughout a region. Applied in Guadeloupe (French West Indies), the MOSAICA-f framework enabled the design of a scenario increasing agricultural added value, food and energy self-sufficiency, employment and the quality of water bodies and reducing greenhouse gas emissions. This sustainable scenario combines new cropping systems tuned to farm types with a reorientation of subsidies, an increased workforce and banning food crop production on polluted soils. It can be used to understand the potential contribution of agriculture to sustainability issues and to help local decision makers define policies that will account for the spatial diversities of farms and fields in a landscape. Beyond the design of such a win-win scenario, MOSAICA-f has revealed trade-offs in the provision of services by agriculture. [ABSTRACT FROM AUTHOR]

In West and Central Africa and in the Caribbean, yam is one of the most important sources of carbohydrates and has a great potential to improve food security. The yam production sector is, however, now challenged by the satisfaction of evolving consumers' preferences. Since little is known about consumers' preferences regarding yams' characteristics, product quality, and the drivers of yam purchase, six focus group discussions were conducted (for a total of 31 participants). Among the purchasing criteria, price was considered more important than the others. It was followed by the external damage, the origin, and the size of the tuber. The most frequently cited consumption criteria were the taste, the texture, and color of flesh after cooking. Taste was considered more important than the other criteria. Three consumers' profiles were established reflecting heterogeneity in preferences, especially as concerns the willingness to pay for yam and consumption habits. They were designated as the Hedonistic, the Thrifty and the Flexible. Our results suggest that innovations can be implemented to sustain and stimulate the development of the yam sector in Guadeloupe. Two main development paths were identified. The first path is the valorization of the great existing diversity of yam varieties and the increase in the level of information for consumers about product attributes such as the cooking mode, the origin, and the mode of production. Building a marketing strategy based on the valorization of this diversity can help maintain and preserve yam's agro-biodiversity and the satisfaction of rapidly evolving consumption habits. The second path is the definition of yam ideotypes that suit consumers' needs. We expect that tailoring the production to consumers' needs will have a positive impact on global food security in the Caribbean region. [ABSTRACT FROM AUTHOR]

Loss of varietal diversity is a worldwide challenge to crop species at risk for genetic erosion, while the loss of biological resources may hinder future breeding objectives. Loss of varieties has been mostly investigated in traditional agricultural systems where variety numbers are dramatically high, or for most economically important crop species for which comparison between pre-intensive and modern agriculture was possible. Varietal dynamics, i.e., turnover, or gains and losses of varieties by farmers, is nevertheless more rarely studied and while we currently have good estimates of genetic or varietal diversity for most crop species, we have less information as to how on farm agro-diversity changes and what cause its dynamics. We therefore investigated varietal dynamics in the agricultural yam system in the Caribbean island of Guadeloupe. We interviewed producers about varieties they cultivated in the past compared to their current varieties, in addition to characterizing yam cropping characteristics and both farm level and producers socio-economic features. We then used regression tree analyses to investigate the components of yam agro-diversity, varietal dynamics and impact of anthracnose on varieties. Our data demonstrated that no dramatic loss of varieties occurred within the last decades. Cultivation changes mostly affected widespread cultivars while frequency of uncommon varieties stayed relatively stable. Varietal dynamics nevertheless followed sub-regional patterns, and socio-economic influences such as producer age or farm crop diversity. Recurrent anthracnose epidemics since the 1970s did not alter varietal dynamics strongly, but sometimes translated into transition from Dioscorea alata to less susceptible species or into a decrease of yam cultivation. Factors affecting changes in agro-diversity were not relating to agronomy in our study, and surprisingly there were different processes delineating short term from long term varietal dynamics, independently of disease risk. Our results highlighted the importance of understanding varietal dynamics, an often overlooked component of agriculture sustainability, in addition to evolutionary forces shaping agro-diversity and genetic diversity distribution within crops. It is also crucial to understand how processes involved do scale up worldwide and for different crop species, so as not to mislead on-farm conservation efforts and efficacy of agro-diversity preservation. [ABSTRACT FROM AUTHOR]

Agri-environmental schemes (AESs) are the main public policy instrument used in Europe to encourage farmers to adopt environmentally-friendly farming practises. Some AESs designed in French West Indies to replace N fertilizers with composts to reduce nitrate pollution and enhance C sequestration have been unsuccessful because few farmers adopted them despite the subsidies offered for the provision of environmental benefits. To explain this low adoption rate, we assessed the agri-environmental and economic impacts of two AESs and compare them with the most widely-applied strategy based on inorganic N fertilizer (NFER), and with an organic strategy based on sewage sludge (SLUD), a free organic amendment. The first AES was proposed in 2007 (AES old ) and only concerned with the use of composts. The second was proposed in 2014 (AES new ) and combines the use of composts and inorganic N fertilizer at a rate 25% lower than NFER. The study was applied to water yam using a crop model to obtain agri-environmental indicators over a period of ten years, which were then used to calculate economic outputs for small and large farms. Although AES old increased C sequestration by 300% and reduced nitrate leaching by 80% compared to NFER, it also reduced yields (13%) and net income for farmers (30%). The subsidy offered by AES old did not compensate the loss of productivity, which explains its low rate of adoption. AES new and SLUD increased C sequestration (350% and 400%) and reduced nitrate leaching (45% and 34%), and maintained yields and net income after five years of implementation. Yields and net income during the first five years were 5–10% lower than under NFER. Although the land area concerned by SLUD is limited because of regulatory constraints, AES new could be a satisfactory policy instrument in French West Indies because it promotes environmental benefits and maintains economic income in the medium term for smallholder using family labour. The economic performance of AESs was lower for large farms; the adoption rate could be improved for these farmers through the implementation of mechanization to reduce labour costs. For both farm types, it may be necessary to increase subsidies during the first five years to offset yield losses during this period and the fixed and transition costs attached to adoption. [ABSTRACT FROM AUTHOR]

Agroecosystems represent 38 % of global land use. Agroecosystems are located close to human settlements and are managed to produce food and fibers, traded in markets. Agroecosystems also produce other goods and services essential to human beings, such as climate regulation, flood mitigation, and landscape amenity. Economists and ecologists have developed the ecosystem services framework to foster the provision of these non-commercial services. Scientists can therefore help decision makers to develop sustainable ecosystems by studying ecosystem services. Here, we analyze the trade-offs of ecosystem services of farming systems. We discuss case studies of mixed perennial crops. The set of ecosystem services provided by these agroecosystems depends on their composition, structure, and management. Complex rule-based management will be required if winegrowers are to maintain an adequate set of ecosystem services across contrasting climatic years. Innovations including cover crops in banana systems can fulfill most of the objective set but will rely on increased farm labor. We then discuss the advantages, challenges, and opportunities to include the description of relations between ecosystem services in cropping system design. We propose to extend the yield gap analysis to ecosystem services, as a service gap analysis. This extension faces methodological questions about the potential provision of a service in a region. We conclude on the challenges that need to be faced if we want to use ecosystem services trade-offs to improve the contribution of agricultural systems to human well-being. [ABSTRACT FROM AUTHOR]

Highlights: [•] We assessed the variability in banana crop yields at regional scale in Martinique. [•] We propose a method that combines spatial autocorrelation measures and a farm survey. [•] The planting stage is the most important aspect for reaching the best yields. [•] We observed no relationship between pesticide use and yields. [•] Targeted policies should promote good plantation practices for smallholders. [ABSTRACT FROM AUTHOR]

Abstract: The ex ante assessment of innovative agro-ecological innovations is a key step in the development of more sustainable crop management systems. To this end, models are useful tools because they make it possible to rapidly assess numerous innovations in different contexts. Whereas many farm optimisation models focusing on the farmer’s strategic decision to adopt new crop management systems have been published, little attention has been given to the ex ante modelling of the dynamic operational impacts of innovation adoption at the farm level. BANAD, a mechanistic model for such applications, is proposed. It allows the ex ante assessment of innovative management systems including new agro-ecological techniques, while taking into account different farming contexts and policy and market conditions. It includes three components: (i) a crop management system model, (ii) a crop model (SIMBA) and (iii) a farming system model. Our results applied to the ex ante assessment of six innovative banana management systems for three contrasted farm types in Guadeloupe showed that the impacts of agro-ecological innovations, which include rotations, improved fallow, intercropping, pest-resistant cultivar, and an integrated organic system, can vary considerably according to (i) the farm type in which the innovation is integrated, (ii) the nature of the agro-ecological innovations, and (iii) the criteria considered and the temporal horizon of the assessment. Innovative intercropping systems that were effective at the field level in terms of the yield improvement and decreased pesticide use could be problematic at the farm level because they increased the workload and decreased income. The adoption of rotations or improved fallow seemed to be relevant for smallholders but could induce a critical period of 1.5–2.5years during which income decreased drastically. Under certain conditions of markets and subsidies, very environmentally friendly innovations that are less productive can however be economically effective. [Copyright &y& Elsevier]

Abstract: Farmers are inundated with advertisements about many innovations that are supposed to increase their yields or reduce environmental impact. However, the benefit of these innovations depends on the farming context. Here we present the ad hoc adaptation of the crop model SIMBA and a method to evaluate 16 innovations in six types of farms previously selected through a typology of the banana farming systems in Guadeloupe. The innovations include regulation of pesticide use, rotations and fallows, intercropping, conditional application of pesticides, resistant cultivars, and integrated systems. Our results show that, for a given innovation, the yield and pesticide reduction vary widely with different farm types. We show that environmentally friendly innovations often cause a greater decrease in yield in more productive farm types. Nevertheless, despite an apparent trade-off between yield and pesticide use, some innovations address both production and environmental issues, e.g., rotation with fallows improved with cover crops, regular fallows, and rotations with pineapples for the most intensive farm types. Our modelling study confirms the importance of innovation-farm type interactions and the usefulness of models for assessing large numbers of technological innovations among a wide range of biophysical and technical contexts. [Copyright &y& Elsevier]

Abstract: Prototyping methods are useful for designing alternative crop management systems (CMS), but they are usually considered mainly at the field level and are poorly equipped to take into account farm diversity in terms of economic, social and natural constraints. This may limit the likelihood of adoption of alternative CMS. This paper proposes a two-step methodological framework that takes into account the diversity of farms in the prototyping of new CMS. The first step of the framework is to design a farm typology that is able to characterise the diversity of current CMS in terms of their technical nature, farming context, and performance. We define a farming context as a set of characteristics at the farm level that are likely to influence the structure and the biophysical and economic performances of CMS at the field level. The typology is designed from a statistical analysis of a set of descriptive variables collected for a sample of farms. The second step of the framework uses this farm typology in a specific work agenda with a panel of experts in order to design a set of alternative CMS prototypes. Prototypes, and the objectives they are meant to reach, are designed by analysing current CMS performances and by mobilising agro-ecological knowledge to identify technical ways to improve them. The typological characterisation of farm diversity then makes it possible to define a set of constraints (SOC) for each farm type. Once the prototypes are designed, the experts use a compatibility indicator (CI) ranging from zero to one to measure the level of compatibility between each prototype and the SOC of each farm type. We define a prototype as compatible with a farm type if the prototype is not likely to increase the constraints of a farm of that type (CI=1). Using this indicator in a process of iterative improvement of prototype design makes it possible to define a set of a priori compatible prototypes for each farm type. The aim of this paper is to present our methodological framework and its application for prototyping new banana crop management systems in Guadeloupe. The six-class typology we developed corresponded to a great diversity of CMS with contrasting performances and farming contexts. The method led to the prototyping of 16 innovative CMS, involving different modalities of intercropping, patterns of pesticide use, choices of hybrid cultivars, and rotations with cover or cash crops. Finally, we discuss the limits of our methodological framework and its utility for improving prototyping approaches. [Copyright &y& Elsevier]

To understand the effects of policy changes on organisations and compositions of cropping systems at regional scale and their contribution to the sustainable development of regions, we built a regional, spatially explicit, multi-scale, bioeconomic model called MOSAICA. This model explicitly incorporates information at field, farm, sub-regional and regional scales to provide cropping system mosaics by way of regional optimisation of the sum of individual farmer's utilities under field, farm and territory biophysical and socio-economic constraints. Its generic structure means it can be used in different regions with geographic information on the location of the field and farm, data on cropping system performance, on location factors and on policy schemes. We used the model in Guadeloupe to test the impact of three scenarios of change on the agricultural subsidy regimes. The model produced three cropping system mosaics which reduced the area under banana and sugarcane, turned specialised banana and sugarcane farming systems into breeding systems while improving the overall contribution of agriculture to sustainable development. The spatially explicit results of changes in ecosystem services, and in farming systems with MOSAICA make it an appropriate decision-aid tool for regional planning. [ABSTRACT FROM AUTHOR]