Test de la vraisemblance entre deux motifs de points

Test de la vraisemblance entre deux motifs de point

Mortality and vigour based indicators for an early diagnosis of vineyard decline

Similar to the forestry industry, the winegrowing sector has experienced a grapevine decline phenomenon over the last twenty years, so that decline is now considered an increasingly widespread problem in many vineyards across the world (De la Fuente et al., 2016). In this work, the relationships between yield, mortality and vegetative vigour were investigated, in both temporal and spatial terms, to identify early diagnosis indicators of vine decline

Overview of grapevine trunk diseases in France in the 2000s

The National Grapevine Trunk Disease Survey was conducted in France from 2003 to 2008 to monitor grapevine trunk diseases (GTDs), eutypa dieback and esca/black dead arm (BDA). Data collected from seven regions, 329 vineyards and 12 cultivars were analysed. There were great variations amongst regions in the incidence of GTDs. For esca/BDA, two groups were distinguished: vineyards in Jura and Charentes had greater incidence (93–95%) than those of Bordeaux, Alsace and Bourgogne (54–82%). Incidence increased in Charentes over the 6-year survey, with the highest values being recorded during the last 2 years. For eutypa dieback, all vineyards of Charentes were affected, with 17 to 25% of vines expressing symptoms; for the other regions, 52 to 80% of vineyards were affected, with incidences below 3%. Cultivars Savagnin and Trousseau in Jura were especially affected by esca/BDA. Instead, Ugni Blanc in Charentes was most affected by eutypa dieback. One cultivar could be significantly more affected in one region than in another. The global health status of the vineyards was also investigated. (i) For four regions, 82% (Jura) to 87% (Alsace) of the grapevines were healthy, but this percentage decreased steadily (67%) in Charentes. (ii) Plants infected by GTDs were 32 and 18% in Jura and Charentes respectively, and only 2.9% in the Bourgogne region. (iii) The unproductive plants, i.e. dead, missing, replanted or restored, represented a significant part of the losses (6.6% in Charentes to 9.9% in Jura). The extension of GTDs is discussed with regard to the abiotic and biotic factors that may favour the diseases

Overview of grapevine trunk diseases in France in the 2000s

The National Grapevine Trunk Disease Survey was conducted in France from 2003 to 2008 to monitor grapevine trunk diseases (GTDs), eutypa dieback and esca/black dead arm (BDA). Data collected from seven regions, 329 vineyards and 12 cultivars were analysed. There were great variations amongst regions in the incidence of GTDs. For esca/BDA, two groups were distinguished: vineyards in Jura and Charentes had greater incidence (93–95%) than those of Bordeaux, Alsace and Bourgogne (54–82%). Incidence increased in Charentes over the 6-year survey, with the highest values being recorded during the last 2 years. For eutypa dieback, all vineyards of Charentes were affected, with 17 to 25% of vines expressing symptoms; for the other regions, 52 to 80% of vineyards were affected, with incidences below 3%. Cultivars Savagnin and Trousseau in Jura were especially affected by esca/BDA. Instead, Ugni Blanc in Charentes was most affected by eutypa dieback. One cultivar could be significantly more affected in one region than in another. The global health status of the vineyards was also investigated. (i) For four regions, 82% (Jura) to 87% (Alsace) of the grapevines were healthy, but this percentage decreased steadily (67%) in Charentes. (ii) Plants infected by GTDs were 32 and 18% in Jura and Charentes respectively, and only 2.9% in the Bourgogne region. (iii) The unproductive plants, i.e. dead, missing, replanted or restored, represented a significant part of the losses (6.6% in Charentes to 9.9% in Jura). The extension of GTDs is discussed with regard to the abiotic and biotic factors that may favour the diseases

Test de la vraisemblance entre deux motifs de points

Test de la vraisemblance entre deux motifs de point

Analyses of the temporal dynamics of fungal communities colonizing the healthy wood tissues of esca leaf-symptomatic and asymptomatic vines.

Esca, a Grapevine Trunk Disease (GTD), is of major concern for viticulture worldwide. Our study compares the fungal communities that inhabit the wood tissues of vines that expressed or not foliar esca-symptoms. The trunk and rootstock tissues were apparently healthy, whether the 10 year-old plants were symptomatic or not. The only difference was in the cordon, which contained white rot, a typical form of esca, in 79% of symptomatic plants. Observations over a period of one year using a fingerprint method, Single Strand Conformation Polymorphism (SSCP), and the ITS-DNA sequencing of cultivable fungi, showed that shifts occurred in the fungal communities colonizing the healthy wood tissues. However, whatever the sampling time, spring, summer, autumn or winter, the fungi colonizing the healthy tissues of asymptomatic or symptomatic plants were not significantly different. Forty-eight genera were isolated, with species of Hypocreaceae and Botryosphaeriaceae being the most abundant species. Diverse fungal assemblages, made up of potentially plant-pathogenic and -protective fungi, colonized these non-necrotic tissues. Some fungi, possibly involved in GTD, inhabited the non-necrotic wood of young plants, but no increase in necrosis areas was observed over the one-year period

A systemic approach to grapevine decline diagnosed using three key indicators: plant mortality, yield loss and vigour decrease

International audienceGrapevine decline, a major global viticulture issue, is defined as a multi-year decrease in vine productivity and/or increase in vine mortality. Although grapevine trunk diseases are one of the most studied causes, the decline is multifactorial and associated with more than 70 factors, including abiotic and biotic hazards. With so many factors to consider, the phenomenon is difficult to understand. Our study aims to make it easier to determine and assess grapevine decline by focusing on three key indicators: yield, mortality and vegetative vigour. We investigated the relationships between these indicators from both a temporal and spatial perspective to propose a set of diagnostic indicators. Thus, we conducted a winegrower survey, a historical analysis of grapevine decline and field measurements of the abovementioned indicators on plot networks in three major French winegrowing regions (see graphical abstract): Bordeaux, Cognac and Languedoc. We found that winegrowers' perceptions of decline were consistent with an objective characterisation based on field measurements of the indicators. Although vine mortality progressively spread over the years, neither the survey nor the historical analysis showed a direct link between decline and yield loss. Rather, large yearly fluctuations in yield, which did not systematically decrease over time, account for this finding. As a result, the mortality rate and the normalised difference vegetation index (NDVI) indicators were shown to be earlier indicators of grapevine decline than yield loss (addressed from the yield achievement ratio, YAR). We performed a multifactorial analysis of the overall data set from the three regions to deepen our understanding of the diversity of declining situations and the underlying environmental and management factors contributing to decline. Finally, two ground-based NDVI indicators and an image-analysis methodology using aerial photographs were proposed as easy-to-obtain indicators of grapevine decline. NDVI indicators were linearly correlated with both the YAR and mortality rate. This study provides a better understanding and promising tools for the early diagnosis of grapevine decline

Mortality and vigour based indicators for an early diagnosis of vineyard decline

A paraître (24 juin 2023)mini technico-scientific paper of 5 pagesInternational audienc

A systemic approach to grapevine decline diagnosed using three key indicators: plant mortality, yield loss and vigour decrease

International audienceGrapevine decline, a major global viticulture issue, is defined as a multi-year decrease in vine productivity and/or increase in vine mortality. Although grapevine trunk diseases are one of the most studied causes, the decline is multifactorial and associated with more than 70 factors, including abiotic and biotic hazards. With so many factors to consider, the phenomenon is difficult to understand. Our study aims to make it easier to determine and assess grapevine decline by focusing on three key indicators: yield, mortality and vegetative vigour. We investigated the relationships between these indicators from both a temporal and spatial perspective to propose a set of diagnostic indicators. Thus, we conducted a winegrower survey, a historical analysis of grapevine decline and field measurements of the abovementioned indicators on plot networks in three major French winegrowing regions (see graphical abstract): Bordeaux, Cognac and Languedoc. We found that winegrowers' perceptions of decline were consistent with an objective characterisation based on field measurements of the indicators. Although vine mortality progressively spread over the years, neither the survey nor the historical analysis showed a direct link between decline and yield loss. Rather, large yearly fluctuations in yield, which did not systematically decrease over time, account for this finding. As a result, the mortality rate and the normalised difference vegetation index (NDVI) indicators were shown to be earlier indicators of grapevine decline than yield loss (addressed from the yield achievement ratio, YAR). We performed a multifactorial analysis of the overall data set from the three regions to deepen our understanding of the diversity of declining situations and the underlying environmental and management factors contributing to decline. Finally, two ground-based NDVI indicators and an image-analysis methodology using aerial photographs were proposed as easy-to-obtain indicators of grapevine decline. NDVI indicators were linearly correlated with both the YAR and mortality rate. This study provides a better understanding and promising tools for the early diagnosis of grapevine decline

The physiology and drivers of Esca leaf symptom development in grapevine

International audienceThe development of Esca leaf symptoms is an erratic and misunderstood phenomenon, which varies among grape varieties and growing regions. Esca development is likely driven by multiple factors, such as pathogen populations, vine physiology, and climatic and viticultural conditions. Grapevine hydraulic functioning is at the core of interactions between biotic and abiotic factors during vascular pathogenesis. Host xylem tissues are colonized by many microbes, including the Esca pathogens. The ascent of sap is affected by soil water availability and climatic conditions. The present study focused on exploring (i) the impacts of Esca leaf symptom development on xylem hydraulic integrity, and (ii) the interactions between drought, climatic conditions, and leaf symptom incidence under controlled conditions and in the field. Leaf symptom development was associated with hydraulic failure caused specifically by xylem occlusion, and subsequent loss of hydraulic conductivity from trunks to leaf laminae. Xylem occlusion by tyloses was specific to Esca leaf symptoms, compared to other types of pre-mature or autumnal leaf senescence, and varied among grape varieties. Using mature potted plants uprooted from a vineyard and naturally infected by Esca pathogens, a long drought (-1MPa of predawn water potential over 3 months) was shown to inhibit Esca leaf symptom development, suggesting that vine water status plays a key role in Esca pathogenesis. Water relations and car-bon dynamics were compared during the combined effects of Esca and drought stress. Using bi-monthly leaf symptom monitoring in 50 vineyards in southern France (over several years) and statistical modelling, it was shown that soil humidity, evapotranspiration, and temperature were the key drivers of Esca incidence and phenology. These results provide new insights on the role of plant physiology and microbial communities, and their interactions with climate, as key drivers in Esca pathogenesis