Overview of the Esca Complex as an Increasing Threat in Vineyards Worldwide: Climate Change, Control Approaches and Impact on Grape and Wine Quality

Esca is an increasing threat to global viticulture causing significant losses by reducing yields, declining or wilting vines, and shortening the productive life of vineyards. Recent findings indicate that the disease may also affect the quality of grapes and the chemical composition of musts and wines. However, more research in this field is needed. Esca seems to affect the ripening process of grapes resulting in lower sugar content, higher acidity, and increased nitrogen concentrations. Regarding polyphenolic compounds, reduction on the concentrations of (+)-catechin, (−)-epicatechin, anthocyanins, and tannins has been observed due to the alteration of flavonoid metabolism. Esca is a complex-chronic disease, where several fungal pathogens act simultaneously or successively, to cause necrosis to the vascular tissues of grapevines by blocking the xylem vessels and by producing enzymes and phytotoxic metabolites. As genotype affects stress response, specific Vitis vinifera cultivars present higher levels of resistance to the disease than others. There is evidence that varieties such as Merlot, Grenache Rouge, and Roussanne are relatively resistant, compared with more susceptible Cabernet Sauvignon, Mourvèdre, Sauvignon Blanc, and Semillon. Another main objective of the current work was to investigate the possible effects of climate change on Esca development and propose appropriate control strategies

Correlation of Wine’s Main Components’ Concentration with the Density of Model Aqueous Solutions and Wine Samples

Density is an important physical property, affecting wine mouthfeel, while it can also be used for monitoring alcoholic fermentation in winemaking. Aim of this study was to elucidate the correlation of ethanol, glucose/fructose, glycerol and tartaric acid on the density of model aqueous solutions and Greek wine samples. Various model aqueous solutions were prepared and density was measured at 20 ˚C. Density of dry white and red wine samples was also measured. A linear regression analysis was performed and theoretical fermentation monitoring curves by density measurement were obtained. The resulting models presented a coefficient of determination over 97.3%. Tartaric acid was found to increase density the most, followed by glucose and glycerol, whereas ethanol decreased density. The knowledge of the correlation of the concentration of each wine component with density may be beneficial to quantitative analysis of wine and to optimizing wine mouthfeel

Isolation, characterisation and evaluation of entomopathogenic fungi for control of the European grapevine moth (Lobesia botrana) (Lepidoptera : Tortricidae) and the Mediterranean fruit fly (Ceratitis capitata) (Diptera : Tephritidae) a recent enemy of wine grapes

Entomopathogenic fungi (EPF) were isolated from various habitats using the Galleria bait method or by collecting infected insect specimens. One strain of Paecilomyces fumosoroseus (Wise) was isolated in the University of Reading. EPF were evaluated for control of the European grapevine moth Lobesia botrana Den. and Schiff. (Lepidoptera: Tortricidae). L. botrana is a serious pest of grapevines worldwide causing severe direct damage to grape berries and indirect damage by allowing access to fungal infections, such as the grey mould Botrytis cinerea (De Bary). Its infestation affects the quality of table grapes and wines. EPF were identified and characterized using PCR amplification and sequencing of the internal transcribed spacer (ITS) region. Spore germination and pathogenicity of EPF under different climatic conditions were examined. EPF germinated well under a broad range of temperature values. Thermal stress had an effect on conidial germination in some cases. Relative humidity (RH) had also a significant influence on both germination and pathogenicity. Fungi germinated better and caused the/highest larval mortality at high RH. Both commercial and wild isolates of EPF caused high mortality of L. botrana when tested against third instar larvae at various temperatures. Except for the primary viability test, isolates were also selected for the control of L. botrana according to their geographical origin. However, the origin of the isolates had no significant influence on mortality of L. botrana. P. fumosoroseus EBAC-O 1 was the most effective isolate against L. botrana as it caused larval mortality as high as 98% at 25°C. EPF also showed a synergistic action with Bacillus thuringiensis (Berliner) when applied in combination treatments against L. botrana. During this study, the Mediterranean fruit fly Ceratitis capitata Wied. (Diptera: Tephritidae) was infesting wine grapes in a vineyard in the periphery of Attica (central Greece). This was the first report of an infestation of wine grapes by the pest, although it was recently found on table grapes in Greece and Brazil. EPF were evaluated as biological control agents of pupae and adults of C. capitata. Results from this study, indicate that EPF have a great potential as biological control agents against the populations of both the European grapevine moth and the Mediterranean fruit fly and could be included in integrated pest management programs for controlling pests in vineyards.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Increase in Total Phenolic Content and Antioxidant Capacity in Wines with Pre- and Post-Fermentation Addition of <i>Melissa officinalis</i>, <i>Salvia officinalis</i> and <i>Cannabis sativa</i>

Herbs are considered substantial sources of antioxidant compounds, playing an important role in medicines, cosmetics, and distillates. Although they have been used in wine since ancient times, especially in Mediterranean regions, there is limited scientific evidence on how the addition of herbs into wine affects its properties. The aim of the present study was to determine the effects of three herbs, Salvia officinalis, Melissa officinalis and Cannabis sativa, with direct extraction in two different conditions: in must (pre-fermentation addition) and in wine (post-fermentation addition) and investigate potential differences between them. Three Greek indigenous grape varieties of Vitis vinifera L. were evaluated (Roditis, Muscat, Fokiano). The extractability of phenolic compounds and the antioxidant capacity of the produced wines were determined by the Folin–Ciocalteu and DPPH methods, respectively. Moreover, HPLC analysis was conducted to identify and quantify rosmarinic acid and caffeic acid, two main components of many Lamiaceae plants. The results indicate that the post-fermentation addition of herbs leads to a significant increase in antioxidant activity and phenolic compounds compared to blank wine. In most cases, the increase is significantly higher in comparison with pre-fermentation addition. Wine, upon the addition of Melissa officinalis, was found to extract the highest amount of total phenols compared to the other two herbs