Exploring zoxamide sensitivity in Plasmopara viticola populations: implications for fungicide management in precision agriculture

Winegrowers must adapt more and more their viticultural practices in order to evolve toward a sustainable viticulture, to be competitive and to improve both the production methods and the quality and typicalness of wines. In this context, ‘Terroir’ studies in Loire Valley vineyards have allowed to build decision aid maps that can be used directly by growers to adjust their practices.

Le comportement de la vigne en terme de fonctionnement thermique et hydrique, influe de manière directe sur la qualité des baies de raisin. L’effet du terroir peut être perçu à travers l’étude de paramètres tels que la précocité, la mise en place de la surface foliaire ou la vigueur. Une expérimentation a été conduite en Val de Loire sur le cépage chenin dans le but de mieux comprendre le rôle des variables liées au terroir sur la croissance et le développement de la vigne et in fine sur la qualité des baies.

In recent years, wine consumption has been evolving towards new trends. On the one hand, awareness of health and responsible consumption has been growing, and with it, the demand for wines with lower or without alcohol content [1].

Volatile thiols are impact aroma compounds, well-known in the literature for imparting tropical fruit aromas such as passion fruit, guava, grapefruit, and citrus in white wines [1]. More recent evidence suggests that tropical fruit aromas are also caused by other aroma compounds besides thiols, such as fermentation esters, or the interaction between these volatile families. Therefore, the objective of this study was to investigate the effects of combining esters and/or thiols to determine their impact on the fruitiness aroma perception of white wines. Pinot gris wine was produced at the OSU research winery and was dearomatized using Lichrolut® EN. Combinations of fermentation volatile compounds were added to the wine, forming the aroma base. Treatment wines were composed of additions of different concentrations and combinations of thiols and/or esters. Samples were subjected to sensory analysis where forty-six white wine consumers evaluated the orthonasal aroma of the wines and participated in Check-All-That-Apply (CATA).

The use of glutathione (GSH) in winemaking has been legitimated recently, according to OIV resolutions OENO 445-2015 and OENO 446-2015 a maximum dose of 20 mg/L is now allowed to use in must and wine. Several studies have proven the benefits of GSH, predominantly in Sauvignon blanc. Thus, oxidative coloration of must and wine is limited, aroma compounds such as volatile thiols are preserved, and the development of ageing flavors such as sotolon and 2-aminoacetophenone is impeded. The protective effect may be explained by the high affinity of GSH to bind o-quinones which are formed during phenolic oxidation and which are known to initiate browning and other oxidative changes. Some researchers have proposed the hydroxycinnamic acid to GSH ratio (HGR) as an indicator of oxidation susceptibility of must and could show that lower ratios yielded lighter musts.