Towards an agroecological viticulture: advances and challenges

To improve its sustainability, viticulture should increase the provision of ecosystem services to decrease its use of inputs and the resulting environmental impact while maintaining high socio-economic performance. Soil functions in relation with their physical, chemical and biological properties can be regulated by proper soil surface management. Cover crops deliver ecosystem services such as protection of soils, better water infiltration and nitrogen fixation. Yet to avoid trade-off between provision of services and production of grapes, the management of cover crops should adapt to climate variations and to the yield objective. Pest and diseases can be regulated by various technical levers, including the control of the grape vegetative development. The assessment of damages due to pests and disease and of their consequences on yield losses is a key component of the design of alternative strategies of crop protection. This knowledge provides clues for designing management strategies with low pesticide use and high agro-ecological performance. A French national network of experiments has quantified the reduction of pesticide use with decision support systems, biocontrol or resistant varieties. To go further the challenge is now to design agroecological vineyards that combine innovations in management, and also in spatial organization at field, farm and landscape scales

Un nouvel indicateur intégré d’évaluation des dégâts occasionnés aux grappes par des bioagresseurs majeurs au vignoble

Communication faite au cours du colloque DinABio2013, 13 et 14 novembre 2013; Tours, FranceAn original and integrative evaluation indicator has been developed to quantify the cumulated damage from major pests and diseases affecting grape bunches: downy mildew, powdery mildew, gray mould and tortricid moths. It made it possible to estimate the associated crop losses and to relate them to the plant protection strategy in different modes of production (organic farming, in-transition, conventional). Thus, overall plant losses were higher in 2012 than in 2011. The in-transition growers’ strategy, with reduced copper doses but increased numbers of sprays, led to a 20% increase in average severity on bunches (essentially due to Downy mildew). The more pragmatic approach of experienced organic growers and conventional ones (higher doses and fewer sprays) reduced the yield losses. The proposed indicator is used for two purposes, i) evaluating the quantitative losses due to pest attacksand ii) differentiating them from other non-pest ones. A more detailed analysis including the impact on performance will be achieved and published soon.Un indicateur d’évaluation, l’IEDG (Indicateur d’Evaluation des Dégâts sur Grappes), a été mis au point pour quantifier les dégâts cumulés dus aux principaux bioagresseurs affectant les grappes de raisin : mildiou, oïdium, pourriture grise et tordeuses. Il permet d’estimer la perte de récolte imputable au cortège parasitaire et de faire le lien avec la stratégie phytosanitaire adoptée (caractérisée ici par l’IFT) et le mode de production (AB, conversion, conventionnel). Ainsi, les pertes sanitaires ont été supérieures en 2012 par rapport à 2011. La stratégie phytosanitaire des viticulteurs en conversion, basée sur des réductions de dose de cuivre de près de 80% et des passages plus nombreux dans les parcelles, n’a pas été efficiente en 2012 avec des sévérités proches de 20% sur grappe, essentiellement dues au mildiou. L’utilisation de doses d’applications supérieures et moins de passages dans les parcelles limite les dommages chez les autres viticulteurs. L’indicateur proposé permet d’évaluer les pertes quantitatives générées par les attaques de bioagresseurs et de les différencier des autres pertes non parasitaires. Une analyse plus fine incluant l’effet région et l’impact sur le rendement devra être réalisée

Développement d'outils microbiologiques et chimiques permettant d'identifier l'origine des pollutions fécales dans les eaux de baignades

La pollution organique issue des effluents d'élevage et des stations d'épuration urbaines conduit à un problème essentiel de santé publique lié à la contamination des eaux de surface où s'exercent des activités sensibles telles que la baignade. S'il est possible de déterminer les pollutions localisées liées à un dysfonctionnement des systèmes de traitement, il est beaucoup plus difficile d'identifier les pollutions organiques diffuses qui participent pourtant majoritairement à la dégradation de la qualité des eaux de surface. La problématique des pollutions diffuses est d'autant plus importante que la nouvelle réglementation européenne concernant les eaux de baignade (Directive 2006/7/CE) demande de constituer des profils de baignade qui nécessitent une identification et une hiérarchisation des sources de pollutions fécales. Le dénombrement de Escherichia coli et des entérocoques intestinaux stipulé par les textes réglementaires européens, représente actuellement le seul outil analytique permettant la mise en évidence d'une contamination fécale du milieu aquatique, sans toutefois différencier l'origine humaine ou animale de cette contamination. Il est donc nécessaire de développer de nouvelles méthodes de détection de la pollution fécale qui puissent non seulement mettre en évidence une contamination mais aussi en indiquer l'origine. C'est d'ailleurs dans cet objectif que s'est développé depuis quelques années, le concept de "Microbial Source Tracking" ("Traceurs de Sources Microbiennes") qui consiste à identifier à l'aide de marqueurs microbiologiques ou chimiques les sources de pollutions fécales. Dans ce contexte, six laboratoires de recherche se sont associés pour développer des techniques de traçage des contaminations fécales afin de proposer un outil opérationnel utilisable pour différencier les sources de pollution, de leur point d'émission jusqu'au milieu récepteur final que constituent les eaux de surface. Les marqueurs qui ont fait l'objet de cette étude sont des molécules chimiques naturelles (stéroïdes, caféine), des molécules de synthèse retrouvées dans les effluents de stations d'épuration ou des rapports de fluorescence de la matière organique ainsi que des micro-organismes (bactériophages, bactéries). A la suite des développements méthodologiques, plusieurs marqueurs ont été sélectionnés : - bactéries appartenant aux groupes bactériens dominants du tractus intestinal humain (Bifidobacterium adolescentis) et porcin (Lactobacillus amylovorus) ; - Bacteroidales spécifiques des humains, porcins et bovins (HF183, Pig-2-Bac, Rum-2-Bac); - génogroupes humains des bactériophages F ARN spécifiques; - rapports de stéroïdes : coprostanol/(24ethylcoprostanol+coprostanol) (R1) et sitostanol/coprostanol (R2); - caféine, benzophénone et tri(2-chloroethyl)phosphate (TCEP)

Les particules biotiques (pathogènes ou non)

National audienc

Trade-offsbetween production and tree biodiversity in coffee agroforests of Guinea andtheir contribution to landscape resilience and farmers livelihood

Coffeeagroforests are typical of the multi-strata cropping systems for which there isa growing interest as a pathway towards sustainable agriculture. Due to theirpluri-specificity, they provide interesting trade-offs between services andproductions that participate to resilience of tropical landscapes and offarmers livelihoods. There is however still little knowledge about thetrade-offs between coffee yield (one of the components of production) and treebiodiversity (one of the component of ecosystems services) on the basis offield observations. Our study aims to assess these trade-offs on coffeeagroforest plots in the region of Guinée Forestière (Guinea). We sampled 27coffee agroforest plots clustered into three shade levels over the coffeestand. On each plot, we characterized (i) canopy structure, (ii) treebiodiversity (iii) coffee yield and (iv) farmers’ practices. Data were alsocollected on forest stands as well as monocrop coffee stands to be used asreference of tree biodiversity and coffee production respectively. Coffee plantdensity was around 1030 (±330) ha-1 without significant difference between theshade levels groups. Tree biodiversity of mature trees and tree seedling wassignificantly higher in forest than in agroforest plots. Within agroforestplots, diversity of mature trees was higher in high shade plots than in lowshaded plots, whereas tree seedling diversity was similar among the shadelevels. Coffee yield decreased when shade cover increased on coffee stands (r²:0.36), with significant differences of yield per coffee plant and per habetween the high shade (129 ± 161 kg. ha-1.year-1) and low shade plots (1002 ±735 kg. ha-1.year-1). The level of intensification of farmers’ practices wasnot correlated with coffee yield and tree biodiversity. Despite a highvariability within a shade level group, coffee yield and mature treebiodiversity were significantly correlated and their relationship followed aconcave form. Using natural forest as a reference for tree biodiversity andmonocrop coffee fields as a reference for yield, discuss the tradeoffs betweeneconomic return from production and biodiversity conservation and how croppingsystem structure and management could help to shift the relationships towards aconvex curve. Among medium shade coffee agroforest plots, some fields suggest asignificant leeway to design agroforest structure and to manage their input inorder to combine, in a profitable way, the production of coffee berry andecosystems services mediated through tree diversity. Including the productsfrom other plants during the lifetime of the agroforest provides additionalleeway in the search for the best trade-offs between farmers’ livelihoods andlandscape resilience

Urban raw or treated wastewater drip-irrigation for lettuce and leek crops: chemical and microbiological properties of soil and plants

International audienceThe aim of this study is to evaluate chemical and microbiological properties of soil, as well as crop yields, when lettuces and leeks are irrigated by raw wastewater (RW), treated wastewater (TW) and drinking water (DW) while in a greenhouse. After 2 lettuce and 1 leek growth cycles, the soil analyses showed an increase of electrical conductivity (EC), Cl, Na and nitrate-nitrogen concentration (NO3-N) after irrigation with TW and particularly with RW compared to DW. The fresh weight of both crop yields was significantly higher with TW compared to DW and RW irrigation. The decay of fecal indicators (E. coli, Enterococcus sp., bacteriophages) in soils was slow, as shown by cultivation-based techniques and qPCR. Fecal indicators were found in plants irrigated with raw wastewater

Urban raw or treated wastewater drip-irrigation for lettuce and leek crops: chemical and microbiological properties of soil and plants

International audienceThe aim of this study is to evaluate chemical and microbiological properties of soil, as well as crop yields, when lettuces and leeks are irrigated by raw wastewater (RW), treated wastewater (TW) and drinking water (DW) while in a greenhouse. After 2 lettuce and 1 leek growth cycles, the soil analyses showed an increase of electrical conductivity (EC), Cl, Na and nitrate-nitrogen concentration (NO3-N) after irrigation with TW and particularly with RW compared to DW. The fresh weight of both crop yields was significantly higher with TW compared to DW and RW irrigation. The decay of fecal indicators (E. coli, Enterococcus sp., bacteriophages) in soils was slow, as shown by cultivation-based techniques and qPCR. Fecal indicators were found in plants irrigated with raw wastewater