BANCAL Marie-Odile

Maître de Conférences : Ecophysiologie des plantes malades

Maître de Conférences : Ecophysiologie des plantes malades


HAL : Dernières publications

  • [hal-01714758] IPSIM-Web, An Online Resource for Promoting Qualitative Aggregative Hierarchical Network Models to Predict Plant Disease Risk: Application to Brown Rust on Wheat

    A qualitative pest modeling platform, named Injury Profile Simulator (IPSIM), provides a tool to design aggregative hierarchical network models to predict the risk of pest injuries, including diseases, on a given crop based on variables related to cropping practices as well as soil and weather environment at the field level. The IPSIM platform enables modelers to combine data from various sources (literature, survey, experiments, and so on), expert knowledge, and simulation to build a network-based model. The overall structure of the platform is fully described at the IPSIM-Web website ( A new module called IPSIM-Wheat-brown rust is reported in this article as an example of how to use the system to build and test the predictive quality of a prediction model. Model performance was evaluated for a dataset comprising 1,788 disease observations at 13 French cereal-growing regions over 15 years. Accuracy of the predictions was 85% and the agreement with actual values was 0.66 based on Cohen’s κ. The new model provides risk information for farmers and agronomists to make scientifically sound tactical (within-season) decisions. In addition, the model may be of use for ex post diagnoses of diseases in commercial fields. The limitations of the model such as low precision and threshold effects as well as the benefits, including the integration of different sources of information, transparency, flexibility, and a user-friendly interface, are discussed. (Marie-Hélène Robin) 21 Feb 2018
  • [hal-04457548] Monitoring the phenology of plant pathogenic fungi: why and how?

    Phenology is a key adaptive trait of organisms, shaping biotic interactions in response to the environment. It has emerged as a critical topic with implications for societal and economic concerns due to the effects of climate change on species' phenological patterns. Fungi play essential roles in ecosystems, and plant pathogenic fungi have significant impacts on global food security. However, the phenology of plant pathogenic fungi, which form a huge and diverse clade of organisms, has received limited attention in the literature. This diversity may have limited the use of a common language for comparisons and the integration of phenological data for these taxonomic groups. Here, we delve into the concept of ‘phenology’ as applied to plant pathogenic fungi and explore the potential drivers of their phenology, including environmental factors and the host plant. We present the PhenoFun scale, a phenological scoring system suitable for use with all fungi and fungus‐like plant pathogens. It offers a standardised and common tool for scientists studying the presence, absence, or predominance of a particular phase, the speed of phenological phase succession, and the synchronism shift between pathogenic fungi and their host plants, across a wide range of environments and ecosystems. The application of the concept of ‘phenology’ to plant pathogenic fungi and the use of a phenological scoring system involves focusing on the interacting processes between the pathogenic fungi, their hosts, and their biological, physical, and chemical environment, occurring during the life cycle of the pathogen. The goal is to deconstruct the processes involved according to a pattern orchestrated by the fungus's phenology. Such an approach will improve our understanding of the ecology and evolution of such organisms, help to understand and anticipate plant disease epidemics and their future evolution, and make it possible to optimise management models, and to encourage the adoption of cropping practices designed from this phenological perspective. (Chloé Delmas) 14 Feb 2024
  • [hal-03890709] Developing a Method to Simulate and Evaluate Effects of Adaptation Strategies to Climate Change on Wheat Crop Production

    Adaptation of cropping management strategies is necessary to ensure the sustainability of our agriculture, which is facing threats arising from climate change. A methodology is proposed to find out and compare the most promising adaptation strategies in this context considering both biotic and abiotic stresses. A set of pre-selected strategies were evaluated based on economic, plant health and environmental criteria. A dedicated workflow combining the STICS crop model, epidemiological models and multi-criteria analysis was designed, implemented and tested for a wheat production situation. Flexible by design, this methodology can consider different criteria weights to be used as an exchange support with stakeholders. (Christophe Gigot) 10 Feb 2023
  • [hal-04573037] Mapping the race between crop phenology and climate risks for wheat in France under climate change

    Climate change threatens food security by affecting the productivity of major cereal crops. To date, agroclimatic risk projections through indicators have focused on expected hazards exposure during the crop’s current vulnerable seasons, without considering the non-stationarity of their phenology under evolving climatic conditions. We propose a new method for spatially classifying agroclimatic risks for wheat, combining high-resolution climatic data with a wheat’s phenological model. The method is implemented for French wheat involving three GCM-RCM model pairs and two emission scenarios. We found that the precocity of phenological stages allows wheat to avoid periods of water deficit in the near future. Nevertheless, in the coming decades the emergence of heat stress and increasing water deficit will deteriorate wheat cultivation over the French territory. Projections show the appearance of combined risks of heat and water deficit up to 4 years per decade under the RCP 8.5 scenario. The proposed method provides a deep level of information that enables regional adaptation strategies: the nature of the risk, its temporal and spatial occurrence, and its potential combination with other risks. It’s a first step towards identifying potential sites for breeding crop varieties to increase the resilience of agricultural systems. (Renan Le Roux) 13 May 2024
  • [hal-01192176] Changement climatique en zone Sud-Est: aperçu des impacts agricoles et forestiers

    absent (Frédéric Levrault) 02 Sep 2015
  • [hal-01595503] ECHAP : un projet pour identifier les possibilités de réduction de l’utilisation des fongicides en utilisant l’architecture des couverts

    ECHAP : un projet pour identifier les possibilités de réduction de l’utilisation des fongicides en utilisant l’architecture des couverts. 45e Congrès du Groupe Français des Pesticides Devenir et impact des pesticides : verrous à lever et nouveaux enjeux (Corinne Robert) 05 Jun 2020
  • [hal-01394816] ECHAP : un projet pour identifier les possibilités de réduction de l’utilisation des fongicides en utilisant l’architecture des couverts

    absent (Corinne Robert) 09 Nov 2016
  • [hal-01000942] The ECHAP project: Reducing fungicide use by associating optimal treatment strategies and canopies promoting disease escape

    absent (Corinne C. Robert) 04 Jun 2014
  • [hal-00850818] An integrated and modular model for simulating and evaluating how canopy architecture can help reduce fungicide applications

    An integrated model coupling architectural canopy development, disease dynamics, pesticide application, pesticide decay and effect of pesticide on disease dynamics has been developed. It allows simulation of the dynamics of epidemics overall a growth season, together with the evaluation of impacts on environment, yield reduction and erosion of pesticide efficiency. This tool allows for a multi-criteria evaluation of different fungicide applications strategies and for designing new strategies that reduce pesticide applications by increasing natural resistance linked to canopy architecture. (Christian Fournier) 08 Aug 2013
  • [hal-01192469] Tolérance du blé tendre aux stress biotiques et abiotiques

    Les divers stress biotiques et abiotiques qu'un peuplement rencontre au cours de son cycle ont souvent comme effet majeur la réduction de la surface foliaire verte. Des travaux préliminaires ont montré une certaine stabilité de la relation entre l’indice foliaire vert intégré pendant le remplissage du grain (IFVI) et le rendement. Ce projet avait pour objectif d'utiliser l'IFVI pour mettre au point un indicateur global de phénotypage "multistress", afin de caractériser le comportement variétal dans différents environnements et ITK. Il devait également approfondir la notion de tolérance, consistant au maintien des performances en présence de stress avéré, et jusqu'ici mal séparée du potentiel de rendement. En mobilisant des acteurs de la recherche (INRA, Lasalle), du développement (Arvalis) et du secteur privé (Saaten Union), une base de données importante a été construite. Les résultats de stations expérimentales ont permis l’élaboration de l’indicateur, tandis que son automatisation "haut débit" était travaillée par ailleurs. Le réseau INRA "ITK blés rustiques" a permis l'évaluation de l'ensemble. On distinguera une tolérance intrinsèque, qui ne dépend que du niveau d’IFVI, donc du potentiel de la culture, et une tolérance spécifique, réponse variétale à un changement de milieu ou d'ITK. Potentiel et rusticité sont largement indépendants, et peuvent donc être sélectionnés conjointement. Par contre notre base de données suggère un trade-off entre les composantes de la rusticité: tolérance, et résistance + échappement, soulignant le besoin de recherche dans ce domaine. A terme, l'indicateur proposé pourra être utilisé pour caractériser les variétés les plus adaptées à un milieu donné et pour aider à la conception de couverts de céréales écologiquement intensifs. (D. Gouache) 27 May 2020
  • [hal-03457521] Comment adapter les échelles de phénologie aux champignons phytopathogènes, et pour quelles utilisations ?

    Aucune échelle globale de notation de la phénologie des champignons phytopathogènes sensu lato n’existe à notre connaissance. Pourtant, un tel outil permettrait d’étudier et de comprendre les impacts du changement climatique et de l’évolution des pratiques sur la santé des plantes. Une première version générique de cette échelle a été construite en identifiant des stades de vie communs aux différents règnes et divisions (stade principal et secondaire) et spécifique de chaque division considérée (stade tertiaire). Toutefois l'utilisation de cette échelle reste inféodée à l’observation de signes et de symptômes sur la plante hôte, ce qui nous a conduit à développer en parallèle un lexique associé à une banque d’images. Nous testons actuellement la pertinence et la généricité de cette échelle sur différents agents pathogènes des cultures (annuelles et pérennes), dont les cycles biologiques sont particulièrement contrastés. (Chloe E. L. Delmas) 30 Nov 2021
  • [hal-01370080] Zymoseptoria tritici development induces local senescence in wheat leaves, without affecting their monocarpic senescence under two contrasted nitrogen nutrition

    Zymoseptoria tritici causes large losses in wheat yield usually related to the losses of green area. However, the issue of whether green area losses result from the local necrosis or from acceleration in the monocarpic apical senescence remains open. The present study examined whether leaf inoculation with Zymoseptoria tritici modifies apical senescence of flag leaf in wheat cultivar Soissons grown under two contrasted nitrogen nutritions. The dynamics of local and apical senescences and the pycnidia number were measured repeatedly throughout the grain filling. Local and apical senescence were adjusted to functions, the parameters of which were analyzed according to nitrogen and inoculation treatments. The intra-leaf gradient of residual nitrogen concentration was measured at plant maturity. The relative rate of apical senescence increased twofold when fertilization was withheld. Both treatments, inoculation and nitrogen, generated a large range of disease that developed to different extents, resulting from different rates and timing. Local necrosis and pycnidia number strongly varied with nitrogen nutrition but necrosis varied in the same extent as apical senescence, thus green area relative loss was unaffected by nitrogen nutrition. By opposition, apical senescence was never affected at any time by the inoculation. Residual nitrogen increased in the inoculated portions of the infected leaves, in correlation with local necrosis, whereas the residual nitrogen in the non-inoculated part of infected leaves stayed at the level of control leaves. Apical senescence was managed at the leaf tissue level, according to nitrogen availability but regardless of disease, a useful output for modelling. (Marie-Odile Bancal) 21 Sep 2016
  • [hal-02885029] Robustness of crop disease response to climate change signal under modeling uncertainties

    Crop fungal diseases threaten food security in the dual context of a growing global population and a warming climate. Leaf rust is one of the most important wheat diseases which can result in yield losses of more than 40 %. When considering these crucial questions, innovative approaches to crop cultivation are clearly required. One essential prerequisite before the development of adaptive strategies to climate change, is to understand and forecast the potential impact of this change on fungal diseases, based on the use of modelling approaches. However, numerous epidemiological models are available; they vary considerably in terms of their complexity, and are based on hypotheses that oversimplify factors that influence the prediction of epidemics. During this study, we implemented six combinations of leaf wetness duration and infection efficiency models to simulate the future evolution of leaf rust of wheat, and compared the resulting trends. Daily and seasonal climatic indicators were inferred from the simulated infection efficiencies, from 1950 to 2100, with two contrasted Representative Concentration Pathways, RCP 4.5 and RCP 8.5, at three sites representative of traditional French wheat production areas. The inferred indicators characterize the intensity and frequency of leaf rust infection, the length and calendar positioning of the longest sequences without infection, and the relevant microclimate. Their absolute values varied considerably depending on the model combinations used, even more than between the present and future climatic periods or RCP scenarios. However, the same trends were observed in the future, with climate change being a significant explanatory variable of the evolution of the six climatic indicators simulated. The results of combining these models showed that the climatic risk of both the frequency and intensity of leaf rust infection would increase during the autumn and winter seasons, and a distinct drop should be expected during the summer, enabling a longer risk-free period. Some important common trends were thus highlighted, reinforcing confidence in the robustness of the results. These findings should be taken into account when designing adaptive strategies that will sustain production under future abiotic stresses while minimizing sanitary risks. (Marie Launay) 04 May 2022
  • [hal-02947485] Septoria tritici: Une première approche de la tolérance aux stress de fin de cycle

    [...] (David Gouache) 24 Sep 2020
  • [hal-01192015] La nuisibilité de la septoriose bientôt cernée

    absent (Philippe Gate) 02 Sep 2015
  • [hal-01003422] Modelling fungal sink competitiveness with grains for assimilates in wheat infected by a biotrophic pathogen

    Experiments have shown that biotrophic fungi divert assimilates for their growth. However, no attempt has been made either to account for this additional sink or to predict to what extent it competes with both grain filling and plant reserve metabolism for carbon. Fungal sink competitiveness with grains was quantified by a mixed experimentalmodelling approach based on winter wheat infected by Puccinia triticina. One week after anthesis, plants grown under controlled conditions were inoculated with varying loads. Sporulation was recorded while plants underwent varying degrees of shading, ensuring a range of both fungal sink and host source levels. Inoculation load significantly increased both sporulating area and rate. Shading significantly affected net assimilation, reserve mobilization and sporulating area, but not grain filling or sporulation rates. An existing carbon partitioning (sourcesink) model for wheat during the grain filling period was then enhanced, in which two parameters characterize every sink: carriage capacity and substrate affinity. Fungal sink competitiveness with host sources and sinks was modelled by representing spore production as another sink in diseased wheat during grain filling. Data from the experiment were fitted to the model to provide the fungal sink parameters. Fungal carriage capacity was 056 001 g dry matter Cd-1 per lesion, much less than grain filling capacity, even in highly infected plants; however, fungal sporulation had a competitive priority for assimilates over grain filling. Simulation with virtual crops accounted for the importance of the relative contribution of photosynthesis loss, anticipated reserve depletion and spore production when light level and disease severity vary. The grain filling rate was less reduced than photosynthesis; however, over the long term, yield loss could double because the earlier reserve depletion observed here would shorten the duration of grain filling. Sourcesink modelling holds the promise of accounting for plantpathogen interactions over time under fluctuating climatic/lighting conditions in a robust way. (Marie-Odile Bancal) 10 Jun 2014
  • [hal-01604466] Climate change effects on leaf rust of wheat: Implementing a coupled crop-disease model in a French regional application

    Leaf rust is responsible for significant wheat yield losses. Its occurrence and severity have increased in recent years, partly because of warmer climate. It is therefore critical to understand and anticipate the effects of climate change on leaf rust. Direct climate effects and indirect effects via host plants that provide a biophysical environment for disease development were both considered. The coupled STICS-MILA model simulates both crop and pathogen dynamics in a mechanistic way and their interaction is managed by two sub-models: one calculating the microclimate within the canopy and the other converting numbers of spores and lesions to affected surfaces. In this study, STICS-MILA was first calibrated and evaluated using leaf rust severity observed at various sites in France for multiple years. STICS-MILA was then run on three contrasting French sites under 2.6, 4.5 and 8.5 RCP future climate scenarios. Results focused firstly on changes in disease earliness and intensity, secondly on disease dynamics, particularly the synchronism between plant and disease developments, and finally on elementary epidemic processes. The calibration and evaluation of STICS-MILA revealed a high sensitivity to the initial amount of primary inoculum (a forcing variable in STICS-MILA) and thus the need to properly simulate the summering and overwintering pathogen survival. The simulations in the context of future climate showed a significant change in host-pathogen synchronism: in the far future, according to RCP 4.5 and 8.5 scenarios, disease onset is expected to occur not only with an advance of around one month but also at an earlier developmental stage of wheat crops. This positive effect results from rising temperatures, nevertheless partly counter-balanced during spring by lower wetness frequency. The crop growth accelerates during juvenile stages, providing a greater support for disease development. The resulting microclimate shortens latency periods and increases infection and sporulation efficiencies, thus causing more infectious cycles. An increase of final disease severity is thus forecasted with climate change. (Julie Caubel) 02 Oct 2017
  • [hal-03660399] Towards a global characterization of winter wheat cultivars behavior in response to stressful environments during grain-filling

    Starting from grain yield, quality and resistance against multiple diseases, the characterization of the cultivar’s behavior increased in recent decades. Needs in quantitative assessments of a larger range of criteria has greatly evolved towards yield stability in a large range of fluctuating environments. Using a large dataset crossing cultivars and environments, we thus explored the relationships between yield and Healthy Area Duration (HAD), as affected by genotype, environment and septoria caused by Zygmoseptoria tritici. A set of indexes was then proposed to properly profile cultivar’s behavior. A curvilinear relationship relating HAD to potential yield was first parameterized. It allows quantifying HAD efficiency. Susceptibility (HAD loss) was differentiated from total tolerance (the ratio between yield loss and HAD loss). Finally the specific tolerance, i.e. not due to HAD level, was quantified. Correlations between indexes pointed out that no trade-off was shown between total tolerance and actual or potential yield as well as disease susceptibility. These correlations partially depended on the nitrogen status of crops, underlining other G×E interactions indexes may trap. Finally, as HAD efficiency appeared more highly linked to actual yield than potential yield we proposed an alternative set on indexes based on Healthy Area Absorption (HAA) that accounted for meteorological variability. Interestingly, these last indexes were insensitive to nitrogen nutrition as well as to cultivar susceptibility to Z. tritici. The developed indexes allowed profiling the cultivars’ behavior under a common range of environments. HAA-based indexes open the way to a useful global characterization of cultivars by breeders. Moreover, HAA can be assessed using high-throughput phenotyping tools. A thorough evaluation of this last point needs to be done. (Marie-Odile Bancal) 05 May 2022
  • [hal-01192184] Absorbed radiation and radiation use efficiency as affected by foliar diseases in relation to their vertical position into the canopy in wheat

    The impact of foliar diseases on crop yield losses is better understood if considering ecophysiological variables together with pathological variables. Although wheat crop losses due to foliar diseases have already been studied with an ecophysiological approach, none of these studies analyzed the vertical diseases distribution into the canopy leaf layers in relation to the canopy size (leaf area index—LAI) and its architecture (light extinction coefficient-k value). Thus, the objectives of the present study were: (i) to understand the importance of the vertical distribution of the foliar diseases in relation to radiation absorption efficiency (RAE) for different LAI levels and canopy architectures and; (ii) to analyze and compare two ways of radiation capture estimations, considering LAI as a total or LAI of each leaf layer separately. The wheat cultivar Klein Pegaso was grown in plots under field conditions during three growing seasons using different nitrogen supply levels and a wide range of severity diseases by using protected and unprotected crops (applying or not fungicides, respectively). Unprotected plots were inoculated with biotrophic and/or necrotrophic pathogens. Biotrophic (Puccinia triticina-leaf rust) and necrotrophic pathogens (Drechslera tritici-repentis-tan spot; Alternaria triticina-leaf blight) constituted the “diseases complex” with different levels and proportions depending on the year and N treatment. Results showed that foliar diseases reduced LAI and GLAI (green leaf area index). GLAI was not only diminished by LAI reductions, but also by increases in NGLAI (non-green leaf area index) due to lesion coverage which reduced light absorption. In spite of the differences observed in LAI between protected and unprotected crops, radiation interception was not affected until LAI dropped down its critical value (i.e. when crop intercept 95% of the maximum radiation possible to be intercepted). The results demonstrated that assuming a uniform distribution of the diseases, lead to underestimations of accumulated absorbed radiation up to 21%, and as a consequence to overestimations of radiation use efficiency (RUE) up to 29% when diseases were concentrated in the lower leaf layers into the canopy. Together with the severity of the pathogen, at the time to decide controlling diseases, farmers should take into account: (i) LAI level, mainly in those crop situations where, during the critical period for yield determination, the LAI is close to or below the critical value; (ii) canopy architecture (k) associated with light distribution into the canopy and (iii) vertical diseases distribution into the crop. (Ramiro Carretero) 02 Sep 2015
  • [hal-02947483] Green loss and nitrogen remobilization along the flag leaf blade of wheat

    [...] (Pierre Bancal) 24 Sep 2020
  • [hal-03659214] Plant–plant communication in variety mixtures plays on disease susceptibility and immunity

    Intraspecific mixtures are a well-known means to modulate epidemics in crops, but knowledge of the immunity they induce is scarce. Pélissier et al. (2021a) selected pairs of susceptible wheat or rice cultivars cross-modulating disease severity and showed that belowground interactions were involved in communicating infection. Healthy neighbours could initiate significant modulations of transcription of basal immunity genes after pathogen inoculation. No general rule was observed between pathosystems, but the demonstration of the effect of healthy neighbours on disease susceptibility and immunity in adjacent plants is a key finding as we strive to understand health in varietal mixtures (Marie-Odile Bancal) 04 May 2022
  • [hal-02947484] Impacts physiologiques et agronomiques de l’application d’une nouvelle spécialité fongicide en T2 sur des couverts de blé

    [...] (Pierre Bancal) 24 Sep 2020
  • [hal-01535231] Identifying traits leading to tolerance of wheat to Septoria tritici blotch

    tIdentifying tolerance traits to diseases in wheat genotypes has an increased interest to minimize pesticideuse and to complement resistance and escape.Yield tolerance to Septoria tritici blotch (STB) was studied pooling up three experiments involving18 genotypes, 5 years and 6 sites in France, amounting to 161 genotype × year × site × managementcombinations. Each combination involves a crop pair (treated or not against foliar diseases) repeated twoto three times. Most crops were grown under high fertilization, and STB was the main disease present inuntreated crops. Crop traits (ear density, grain number and weight, area of leaf laminas) were recorded;green area of leaf laminas over time was fitted to a Gompertz equation, producing metrics for senescencetraits (time and duration).Over the whole dataset, LAI from 1.1 to 7.5 m2m−2; yields from 280 to 1122 gDM m−2and relative yieldlosses up to 70% were recorded. Fungicide treated crops exhibited slightly larger ear density and leaf lam-ina area independently of the intensity of epidemics. As an overall trend, yield became more determinedby source traits when epidemics occurred. Yield loss was proportional (r2= 0.7) to senescence advanceby disease. Decrease in grain number and weight were also correlated (r2= 0.4 and 0.8, respectively) toyield loss. Two epidemic indices were built to compare data across year × site combinations. Then yieldin untreated crop was predicted (r2= 0.87) from yield in corresponding treated crop, and interactionof epidemic indices with traits of the treated crops that therefore were pointed out as responsible fortolerance variability. Late senescing crops exhibited a greater tolerance to epidemics. Conversely, grainweight was a major key of intolerance. To minimize the trade-off between yield potential and toleranceit is thus suggested to maximize grain number.This study represents a first step in identifying key traits involved in tolerance to STB in varyingagronomic conditions and cultivars (Pierre Bancal) 08 Jun 2017
  • [hal-01959678] Wheat Leaf Rust Uredospore Production and Carbon and Nitrogen Export in Relation to Lesion Size and Density

    To develop mechanistic yield loss models for biotrophic fungi, we need better account for the export of dry matter, carbon and nitrogen from the leaf into the spores. Three experiments in controlled environment chambers were performed to study the dynamics of uredospores production of Puccinia triticina on seedling leaves of wheat in relation to time, lesion density and sporulating surface area. The detrimental effect of lesion density on the sporulation capacity of brown rust lesions was confirmed : when lesion density increased, spores production per lesion strongly decreased. However, our results showed that increasing lesion density also greatly reduces lesion size. A model was developed to summarize these relationships. The main conclusions of our work is that the density effect on spore production per lesion was accounted for by lesion size : when sporulation was related to the sporulating surface area, it became independent of density. As well, carbon and nitrogen contents of the spores were in dependent of lesion density. Our data suggest that when nitrogen available in the host is limiting, spore production is reduced but nitrogen content of spores tend to remain stable. (Corinne Robert) 18 Dec 2018
  • [hal-01799549] Impact of climate change on fungal diseases of agroecosystems

    The study of climate change (CC) impact on pathosystems requires more attention. For several aerial fungal diseases of crop ecosystems facing climate change, the network ACCAF-Clif allowed a strong interaction between research and extension. In this framework, modelling of epidemiological risks under past or future climate was implemented in relation with crop adaptation resulting from climate change. Experimental results showed that taking into account the diversity of plant pathogens has to be priotarized. The balance between integration approach using modelling and experimental multifactorial comparison makes it possible to analyse and predict the behaviour of simple or a fortiori multiple pathosystems. Operational results include CC perception by agricultural sectors, modelling outputs on two pathosystems (potato mildew, wheat-airborne diseases) under climate change, and using scenarios of adaptation to abiotic stresses in external forcing of pathosystem models. Perspectives will involve (i) taking into account patterns of local adaptation of pathogens to climate, (ii) further developping adaptation of crop ecosystems to abiotic stresses and their impacts on crop diseases, and (iii) confronting pathosystem evolution under future climate to ecological niche evolution in relation to pathogen emergence. (Laurent Huber) 05 Jun 2020
  • [hal-01678092] Wheat lines exhibiting variation in tolerance of Septoria tritici blotch differentiated by grain source limitation

    Septoria tritici blotch (STB) is the most damaging disease of wheat crops in Europe. Because of the partial nature of genotypic resistance or the increasing resistance against fungicides, the tolerance, i.e. maintaining yield in the presence of expressed disease, is a relevant alternative. Tolerance is generally estimated through the yield loss per unit of source reduction, contrasts of tolerance between genotypes have been observed previously suggesting that either increasing the source availability or improving the use of stored assimilate could improve tolerance. This paper aims at developing a source/sink approach to understand the tolerance mechanism and identifying potential traits to increase tolerance of STB. A field experiment was designed to explore the relation between tolerance of STB and source/sink balance. Based on six wheat genotypes contrasting for tolerance exposed to natural STB epidemics, late nitrogen fertilization and a 50% spikelet removal were applied to change the source/sink balance. The tolerance of genotypes was quantitatively estimated over three additional field experiments. We found that STB tolerance was correlated with traits of healthy crops (high individual grain weight and high proportion of green leaf lamina area as leaf 3; flag leaf = leaf 1). The spikelet removal revealed a highly variable degree of source limitation for grain filling amongst the six genotypes. Thus, we proposed an easily calculated index that highly correlated positively with the labor intensive estimation of STB tolerance. Finally, potential yield and tolerance were not correlated, which suggests that breeding for yield performance and tolerance could be possible. (François Collin) 08 Jan 2018
  • [hal-01811439] Thermal generalist behaviour of invasive Puccinia striiformis f. sp. tritici strains under current and future climate conditions

    Yellow rust is a devastating wheat disease. Since 2000, Puccinia striiformis f. sp. tritici strains PstS1 and PstS2 have become adapted to high temperatures and have spread worldwide. By 2011, Warrior strains had invaded both warm and cold areas of Europe. This study questioned whether thermal aptitude promoted the spread of Warrior strains, similar to PstS1/PstS2, by comparing infection efficiency (IE) at five temperatures and latent period (LP) under warm and cold regimes for Warrior isolates and pre‐2011 reference strains on two susceptible wheat varieties. The Warrior isolates showed a range of IE and LP responses to temperature that was intermediate between the northern reference isolates adapted to cold conditions and both the southern and invasive PstS2 isolates adapted to warm conditions. Warrior isolates had the highest IE under optimal temperatures of 10 and 15 °C, and displayed reduced infectivity under the warmest (20 °C) and coldest (5 °C) temperatures. Warrior strains acted as thermal generalists and the reference isolates acted as specialists. An IE thermal response was used to simulate the development of each isolate under future climate scenarios in a temperate and Mediterranean region. Isolates had the same ranking for yearly IE over the three 30‐year periods (1971–2000, 2021–2050, 2071–2100) and both locations, with a slight infection increase in the future. However, in the future IEs increased in earlier months. The thermal generalist profile of Warrior isolates for IE was confirmed, with an intermediate capacity to tolerate warming climate, whereas the southern isolates are better adapted to warm conditions, but do not have the virulences necessary to develop on current varieties. (Claude Pope de Vallavieille) 08 Jun 2018
  • [hal-01192165] Changement climatique et culture du blé: l'essentiel des impacts

    absent (Marie-Odile Bancal) 02 Sep 2015
  • [hal-01192104] Foliar diseases affect the eco-physiological attributes linked with yield and biomass in wheat (Triticum aestivum L.)

    Foliar diseases are the main biotic cause of yield loss in wheat crops (Triticum aestivum L.) in Argentina and other regions around the world. Most of the studies on foliar diseases take a phytopathological perspective, but few studies have analyzed the problem with an eco-physiological approach aimed at the understanding of which crop traits are affected by foliar diseases. The present study was designed to determine the effects of a foliar disease complex (including leaf rust, Septoria leaf blotch and tan spot), on (i) grain yield and (ii) the physiological components of biomass production; intercepted radiation (RI) and radiation use efficiency (RUE), in bread wheat crops growing under contrasting agronomic and environmental conditions (i.e. different cultivars, years, location and nitrogen supply). The experiments were carried out during 4 years in different locations (three in the rolling pampas of Argentina and one in northern of France). Five different commercial wheat cultivars were sown on early (E) and late (L) sowing dates (SD); and two contrasting nitrogen availability and two fungicide treatments (protected and unprotected)were applied. Foliar diseases appeared during the grain filling period and affected both, leaf area duration (LAD) and healthy area duration (HAD) during that period. Foliar diseases reduced both, above-ground biomass at harvest (1533 and 1703 gm-2 for unprotected and protected treatments, respectively) and grain yield (646 and 748 gm-2 for unprotected and protected treatments, respectively) without important effects on harvest index. Biomass reductions after anthesis, due to the effects of foliar diseases, were associated with a reduced capacity of the canopy to absorb solar radiation more than any effect on RUE. However, RUE was consistently lower—when leaf rust was the predominant disease in the crop, suggesting that this biotrophic pathogen could affect the photosynthetic activity at the leaf or canopy level. (Roman A. Serrago) 02 Sep 2015
  • [hal-01192328] Climate change in the South-East zone: the main agricultural and forest impacts

    absent (Frederic Levrault) 06 Jun 2020
  • [hal-01192275] Dry matter partitioning parameterization in wheat infected by sporulating wheat leaf rust (Puccinia triticina)

    absent (Marie-Odile Bancal) 02 Sep 2015
  • [hal-01192329] Evolution of some pathosystems on wheat and vines

    absent (David Gouache) 06 Jun 2020
  • [hal-01192253] Changement climatique et cultures de blé et de colza : l’essentiel des impacts

    absent (Marie-Odile Bancal) 04 Jun 2020
  • [hal-01173747] Climate change in the Centre-North zone: a survey of the agricultural impacts

    absent (Frederic Levrault) 06 Jun 2020
  • [hal-01192148] Evolution de quelques pathosystèmes sur le blé et la vigne

    absent (D. Gouache) 02 Sep 2015
  • [hal-01192161] Changement climatique en zone Ouest: aperçu des impacts agricoles et forestiers

    absent (Frédéric Levrault) 02 Sep 2015
  • [hal-01192243] A general cultivar tolerance to stresses and its modeling in the case of wheat affected by STB (Septoria tritici)

    absent (Pierre Bancal) 02 Sep 2015
  • [hal-01192193] Local dispersal of Puccinia triticina and wheat canopy structure

    Local dispersal of leaf rust and wheat canopy structure. Phytopathology 99:1216-1224. The development of dynamic models jointly to simulate host growth and disease spread necessitates a precise description of pathogen dispersal in relation to canopy structure. In this study, we measured disease spread from a single infected leaf positioned at different heights in wheat canopies. The resulting lesion distribution was described along crop rows and over three leaf layers. The spore sources, although limited to a single leaf, nearly saturated the host surface accessible to the spores. Most of the lesions were found within 30 to 40 cm of the source. The vertical position of the source influenced the lesion distribution and the steepness of the disease gradients. The leaf layer and the wheat row that contained the spore source were the most infected. Close to the source, a few heavily infected leaves produced steep disease gradients, whereas spore diffusion resulted in shallower gradients along the adjacent rows and on the other leaf layers. Depending on the precision needed, the lesion distribution can be described either at the level of leaf layers or by dispersal gradients for each row and leaf layer. (Lise Frezal) 02 Sep 2015
  • [hal-01192276] Impact of Septoria disease on apical senescence in wheat

    absent (Rym Ben Slimane) 02 Sep 2015
  • [hal-01192195] Late foliar diseases in wheat crops decrease nitrogen yield through N uptake rather than through variations in N remobilization

    Background and Aims French wheat grains may be of little value on world markets because they have low and highly variable grain protein concentrations (GPC). This nitrogen-yield to yield ratio depends on crop nitrogen (N) fertilization as well as on crop capacity to use N, which is known to vary with climate and disease severity. Here an examination is made of the respective roles that N remobilization and post-anthesis N uptake play in N yield variations; in particular, when wheat crops (Triticum aestivum) are affected by leaf rust (Puccinia triticina) and Septoria tritici blotch (teleomorph Mycosphaerella graminicola). Methods Data from a 4-year field experiment was used to analyse N yield variations in wheat crops grown either with a third or no late N fertilization. Natural aerial epidemics ensured a range of disease severity, and fungicide ensured disease-free control plots. The data set of Gooding et al. (2005, Journal of Agricultural Science 143: 503-518) was incorporated in order to enlarge the range of conditions. Key Results Post-anthesis N uptake accounted for a third of N yield whilst N remobilization accounted for two-thirds in all crops whether affected by diseases or not. However, variations in N yield were highly correlated with post-anthesis N uptake, more than with N remobilization, in diseased and also healthy crops. Furthermore, N remobilization did not significantly correlate with N yield in healthy crops. These findings matched data from studies using various wheat genotypes under various management and climatic conditions. Leaf area duration ( LAD) accurately predicted N remobilization whether or not crops were diseased; in diseased crops, LAD also accurately predicted N uptake. Conclusions Under the experimental conditions, N yield variations were closely associated with post-anthesis N uptake in diseased but also in healthy crops. Understanding the respective roles of N uptake and N remobilization in the case of diseased and healthy crops holds the promise of better modelling of variations in N yield, and thus in GPC. (Marie-Odile Bancal) 02 Sep 2015
  • [hal-01173746] Climate change in the West zone: the main agricultural and forest impacts

    absent (Frederic Levrault) 06 Jun 2020
  • [hal-01192327] Climate change and the wheat crop

    absent (Marie-Odile Bancal) 06 Jun 2020
  • [hal-01192198] Modélisation des interactions épidémie - couvert végétal : De la recherche à la mise au point d'outils opérationnels pour la protection intégrée des cultures

    La complexité des interactions entre les maladies et les couverts végétaux rend difficile la prise en compte de nombreux facteurs influençant celles-ci. Cette complexité limite l'élaboration d'outils fiables d'aide à la décision, la conception d’itinéraires techniques freinant les maladies, et l’évaluation variétale. Un projet collaboratif entre Arvalis et l’UMR EGC (INRA AgroParisTech), a permis d'élaborer des outils opérationnels, stables, fondés sur la compréhension des relations entre couvert et maladie, prenant la septoriose du blé comme "modèle" dans le cadre de l’Unité Mixte de Technologie Pivert. Ce projet repose sur un cadre conceptuel commun identifiant et hiérarchisant les différents points-clés des interactions entre épidémie et couvert. Les résultats, et la démarche, sont déclinés dans cette communication, et présentés en détail dans les posters auxquels il est fait référence. (D. Gouache) 02 Sep 2015
  • [hal-01192156] Changement climatique en zone Centre-Nord : aperçu des impacts agricoles

    absent (Frédéric Levrault) 02 Sep 2015
  • [hal-01192283] Regulation of grain N accumulation in wheat

    absent (Rym Ben Slimane) 02 Sep 2015
  • [hal-02947486] Tolérance du blé tendre aux stress biotiques et abiotiques » C2008-02 Blé tendre

    [...] (Pierre Bancal) 24 Sep 2020
  • [hal-01173313] Climatic indicators for crop infection risk: Application to climate change impacts on five major foliar fungal diseases in Northern France

    Since weather has a major influence on the occurrence and development of crop diseases, valuable insight toward future agricultural planning emerges with assessment tools to evaluate fungal disease pressure and crop regional suitability under projected future climatic conditions. The aim of this study was to develop two climatic indicators, the average infection efficiency (AIE) and the number of infection days (NID), to quantify the potential effects of weather on the intensity and occurrence of pathogen infection. First, a simple and continuous infection function accounting for daily temperature and leaf wetness duration variations was implemented. The function was then parameterized from published data sets for five major contrasting fungal diseases affecting crops in Northern France: phoma of oilseed rape, late blight of potato, downy mildew of grape, leaf rust of wheat and net blotch of barley. Finally, AIE and NID were calculated for the recent past (1970–2000) and the future A1B climate scenario (2070–2100). An overall decrease in the risk of infection was shown for potato late blight and downy mildew of grapevine for all months during the period when the host plant is susceptible to infection. There were greater differences for the other three diseases, depending on the balance between warmer temperatures and lower humidity. The future climate would result in a later onset of disease and higher infection pressure in late autumn. In spring, for brown rust of wheat and net blotch of barley, the climatic risk for infection is expected to occur earlier but would result in lower infection pressure in May. These findings highlighted the need to use an infra-annual (monthly or seasonally) scale to achieve a relevant analysis of the impact of climate change on the infection risk. The described indicators can easily be adapted to other pathogens and may be useful for agricultural planning at the regional scale and in the medium term, when decision support tools are required to anticipate future trends and the associated risks of crop diseases. (Marie Launay) 07 Jul 2015
  • [hal-01191942] Modelling wheat growth and yield losses from late epidemics of foliar diseases using loss of green leaf area per layer and pre-anthesis reserves

    Background and Aims Crop protection strategies, based on preventing quantitative crop losses rather than pest outbreaks, are being developed as a promising way to reduce fungicide use. The Bastiaans' model was applied to winter wheat crops (Triticum aestivum) affected by leaf rust (Puccinia triticina) and Septoria tritici blotch (STB; Mycosphaerella graminicola) under a range of crop management conditions. This study examined (a) whether green leaf area per layer accurately accounts for growth loss; and (b) whether from growth loss it is possible to derive yield loss accurately and simply. Methods Over 5 years of field experiments, numerous green leaf area dynamics were analysed during the post-anthesis period on wheat crops using natural aerial epidemics of leaf rust and STB. Key Results When radiation use efficiency (RUE) was derived from bulk green leaf area index (GLAI), RUEbulk was hardly accurate and exhibited large variations among diseased wheat crops, thus extending outside the biological range. In contrast, when RUE was derived from GLAI loss per layer, RUElayer was a more accurate calculation and fell within the biological range. In one situation out of 13, no significant shift in the RUElayer of diseased crops vs. healthy crops was observed. A single linear relationship linked yield to post-anthesis accumulated growth for all treatments. Its slope, not different from 1, suggests that the allocation of post-anthesis photosynthates to grains was not affected by the late occurring diseases under study. The mobilization of pre-anthesis reserves completely accounted for the intercept value. Conclusions The results strongly suggest that a simple model based on green leaf area per layer and pre-anthesis reserves can predict both growth and yield of wheat suffering from late epidemics of foliar diseases over a range of crop practices. It could help in better understanding how crop structure and reserve management contribute to tolerance of wheat genotypes to leaf diseases. (Marie-Odile Bancal) 02 Sep 2015
  • [hal-01192230] Potential impact of climate change on brown wheat rust : a preliminary study based on biophysical modelling of infection events and plant-pathogen interactions

    We address the question of potential climate change effects on interactions between wheat and brown rust. The paper is based on biophysical modelling approaches and a climate scenario for four contrasting French sites provided within a project of the French National Research Agency. Predicted distributions of surface wetness duration and infection risk were calculated with the help of a big-leaf model of mass and energy transfer, while plant-pathogen interactions were simulated with the biophysical model, Ceres-wheat, enriched with recent knowledge on wheat growth in the face of late epidemics. No particular trend was discernible concerning the infection rates due to opposite evolutions of two major variables: temperature and surface wetness duration. Yield of diseased crops remained also nearly constant due to a slight decrease of the healthy crop yield combined with a lesser evolution of the disease. (Romain Roche) 02 Sep 2015
  • [hal-02947495] Does Zymoseptoria tritici accelerate leaf apical senescence in winter wheat plants cv. Soissons grown under contrasted nitrogen conditions?

    [...] (Pierre Bancal) 24 Sep 2020

Date de modification : 06 novembre 2023 | Date de création : 04 août 2010 | Rédaction : Com Ecosys - S. Formisano