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Grapevine curettage was re-introduced in France in the early 2000s, and is important for facilitating recovery of plants from esca disease. This surgical practice involves removal of deadwood of vines with leaf symptoms, focusing on white rot generally observed at the centres of grapevine trunks. Assessment of the efficacy of this practice was initiated in the Bordeaux region in 2014. One 'Sauvignon Blanc' vineyard severely affected by esca was initially surveyed in the summer of 2014, to identify and treat vines with esca foliar symptoms. Annually thereafter, from 2014 to 2018, selected vine stocks were curetted. Two other 'Sauvignon Blanc' vineyards also displaying high levels of esca damage were added to the study in 2015 and 2016. Curettage treatments ceased in 2018, resulting in 11 trials (vineyard × year combinations). In total, 856 vines (422 curetted and 434 control vines) were then surveyed annually up to 2021, for assessments and comparisons of esca development. At each site, plants with esca symptoms recovered well after curettage: on average 85% of all curetted vines became asymptomatic the year immediately after the treatment. Six years after treatment, for curettage campaigns carried out in 2014 and 2015, more than half of the curetted vines were symptom-free, whereas <12% of the control vines were asymptomatic, and gradual loss of efficacy was observed at each site. The mean annual proportion of efficacy erosion was approx. 8% per year. This study highlights the possible short- and midterm benefits of trunk surgery to enable recovery of esca-affected vines, and for them to recover and remain leaf-asymptomatic for several years. [ABSTRACT FROM AUTHOR]

Pruning experimental studies have been performed in different vineyards, in France, USA and Australia. This article investigates and models the effects of pruning quality on the installation of desiccation cones and wood necrotization. Two different modalities of pruning, short and high pruning, were performed at the same period each year on three cultivars in Bordeaux (Cabernet Sauvignon and Sauvignon Blanc) and Charente (Ugni Blanc) wine regions. In the short typ of pruning, the diaphragm was damaged but, in the high one, a 2–3 cm woody length was left immediately above the diaphragm. None of the three cultivars showed any correlation between necrosis length and spur diameter (R2 < 0.1925). Analysis of the Ugni Blanc, 8 months after pruning, showed significantly more necrosis length (>60%) than either Cabernet Sauvignon (31–41%) or Sauvignon Blanc (25–55%). Desiccation cone necrotization rates also varied with the vintage, particularly for Ugni Blanc. 4 or 8 months after pruning, the newly-installed desiccation cones could then be analysed. High pruning stopped the desiccation cones at the diaphragm, which ensured that the sap flow path remained unaffected. [ABSTRACT FROM AUTHOR]

Rootstocks are the link between the soil and scion in grapevines, can provide tolerance to abiotic and biotic stresses, and regulate yield and grape quality. The vascular system of grapevine rootstocks in nurseries is still an underexplored niche for research, despite its potential for hosting beneficial and pathogenic microorganisms. The purpose of this study was to investigate the changes in the composition of fungal communities in 110 Richter and 41 Berlandieri rootstocks at four stages of the grapevine propagation process. Taxonomic analysis revealed that the fungal community predominantly consisted of phylum Ascomycota in all stages of the propagation process. The alpha-diversity of fungal communities differed among sampling times for both rootstocks, with richness and fungal diversity in the vascular system decreasing through the propagation process. The core microbiome was composed of the genera Cadophora, Cladosporium, Penicillium and Alternaria in both rootstocks, while the pathogenic genus Neofusicoccum was identified as a persistent taxon throughout the propagation process. FUNguild analysis showed that the relative abundance of plant pathogens associated with trunk diseases increased towards the last stage in nurseries. Fungal communities in the vascular system of grapevine rootstocks differed between the different stages of the propagation process in nurseries. Numerous genera associated with potential biocontrol activity and grapevine trunk diseases were identified. Understanding the large diversity of fungi in the rootstock vascular tissue and the interactions between fungal microbiota and grapevine will help to develop sustainable strategies for grapevine protection. [ABSTRACT FROM AUTHOR]

Fungal species involved in Esca cause the formation of grapevine wood necroses. It results in the deterioration of vascular network transport capacity and the disturbance of the physiological processes, leading to gradual or sudden grapevine death. Herein, for two consecutive growing seasons, a detailed analysis of the structural (wood necrosis and leaf discoloration) and physiological parameters related to the water use of healthy and esca-symptomatic grapevines was conducted. Measurements were carried out on 17-year-old grapevines that expressed, or not, Esca-leaf symptoms in a vineyard of the Bordeaux region (France). Whole-plant transpiration was recorded continuously from pre-veraison to harvest, using noninvasive sap flow sensors. Whole-plant transpiration was systematically about 40–50% lower in Esca-diseased grapevines compared with controls, and this difference can be observed around 2 weeks before the first Esca-foliar symptoms appeared in the vineyard. Unlike grapevine sap flow disruption, structural (e.g., leaf discolorations), functional (e.g., stomatal conductance, photosynthetic activity, phenolic compounds), and genetic (e.g., expression of leaf-targeted genes) plant responses were only significantly impacted by Esca at the onset and during leaf symptoms development. We conclude that sap flow dynamic, which was related to a high level of a white-rot necrosis, provides a useful tool to predict plant disorders due to Esca-grapevine disease. [ABSTRACT FROM AUTHOR]

Esca is a Grapevine Trunk Disease (GTD) caused by a broad range of taxonomically unrelated fungal pathogens. These attack grapevine wood tissues inducing necroses even in the conductive vascular tissues, thus affecting the vine physiology and potentially leading to plant death. However, the influence of Esca on leaf and whole-plant water transport disruption remains poorly understood. In this paper, a detailed analysis of xylem-related physiological parameters in grapevines that expressed Esca-foliar symptoms was carried out. The experiments were conducted in a vineyard in the Bordeaux region (France) on cv. Cabernet-Sauvignon (Vitis vinifera L.) grapevines, which were monitored for Esca-foliar symptoms over a two-year period. Heat dissipation sap-flow sensors were installed during the summer on grapevines having expressed or not Esca-foliar symptoms. Leaf water potential, stomatal conductance and leaf transpiration were also measured. Physiological monitoring showed that sap flow density and whole-plant transpiration of Esca-infected grapevines decreased significantly a week before the first foliar symptoms appeared. When atmospheric water demand (Vapour Pressure Deficit, VPD) was the highest, both parameters tended to be about twice as low in symptomatic grapevines as in asymptomatic ones. Sap flow density data at the maximum transpiration-time, was systematically 29–30% lower in Esca-infected grapevines compared to control plants before or after the appearance of Esca-foliar symptoms. This trend was observed whatever the temperatures and VPD values measured. In Esca-diseased plants, larger amounts of necrotic wood, mainly white rot, were found in the trunk and cordon of symptomatic grapevines compared to healthy ones, suggesting necroses have an influence in reducing the whole-plant hydraulic capacity. This study reveals that the use of physiological monitoring methods, together with the visual monitoring of foliar symptoms, could prove useful in providing accurate measurements of Esca disease severity. [ABSTRACT FROM AUTHOR]

Grapevine wood hosts diverse fungal species, including pathogens that cause grapevine trunk diseases and wood decomposers, with detrimental effects on yields. This study focuses on the effects of two pruning systems, minimal (min-) or spur-pruning, on the community of trunk pathogens and other wood-colonizing fungi in the trunks of two cultivars, Mourvèdre and Syrah. Culture and DNA-based methods were used to describe the fungal communities. In both cultivars, especially Syrah, spur-pruned vines had more wood necrosis than min-pruned vines, and the community of spur-pruned Syrah was distinguished by its single-stranded conformational polymorphism (SSCP) profile. Diversity profiles of all 88 cultivated taxa and canonical correspondence analyses of the 15 most frequently isolated taxa revealed differences in community structure due to pruning system, trunk location, and/or wood type. Greater levels of wood necrosis may be due to the composition of the fungal community rather than to a greater diversity of taxa. [ABSTRACT FROM AUTHOR]