Temperature variations in the Walla Walla valley American Viticultural Area

Grapevines are grown grafted in most viticultural regions. Grapevine rootstocks are either hybrids or pure species of different American Vitis spp. (particularly V. berlandieri, V. rupestris and V. riparia), which were primarily used to provide root resistance to the insect pest Phylloxera. In addition to Phylloxera resistance, grapevine rootstocks were also selected in relation their resistance to various abiotic stress conditions. Future rootstocks should have the potential to adapt viticulture to climate change without changing the characteristics of the harvested product. However, high grafting success rates are an essential prerequisite to be able to use them with all the varieties. The objective of this work is to develop quantitative techniques to characterize graft union formation in grapevine.

Oenological tannins are classified as hydrolysable and condensed tannins. Their use in winemaking is only authorized, to facilitate wine fining. Nevertheless, tannins could also be used to prevent laccase effects.

Erysiphe necator and Plasmopara viticola are the causal agents of powdery and downy mildew on grapevines, leading to significant economic losses. Numerous chemical treatments are applied to control these diseases, leading to environmental problems and the appearance of resistance to these products. Therefore, the study of new strategies to achieve the objectives of sustainable development is a priority. In this sense, the use of new varieties resistant to these diseases may be an option of interest. The objective of this work was to analyze the degree of resistance of 9 varieties with downy mildew resistance genes (Rpv3 and/or Rpv12), four of which also carry a powdery mildew resistance gene (Ren 1) by in vitro inoculation assays.

Some wood substances such as ellagitannins (vescalagin, castalagin, grandinin, roburins (A, B, C, D, E)…) can be extracted during wine ageing in oak barrels. The level of these hydrolysable tannins in wine depends of the species and origin of oak wood as well as its treatment during barrel realization.

Must fermentation is a complex process influenced by various factors, especially microbiological activities. The characteristics and quality of the resulting wine are closely linked to the stages that unfold throughout this progression.