Stilbenoid-Enriched Grape Cane Extracts for the Biocontrol of Grapevine Diseases

Grape canes are under-valued byproducts of viticulture that accumulate large amounts of stilbenoids. These specialized metabolites are phytoalexins of Vitis vinifera that play a keyrole in defence of Vitis vinifera against pathogens. Since in vitro assays demonstrated the antifungal activity of several pure stilbenoids, grape cane extracts (GCE) have been proposed as eco-friendly alternative to classical fungicides in a context of sustainable viticulture. Following the grape pruning during winter, a storage period associated to an efficient extraction procedure, are determinant to obtain GCE with optimal stilbenoid titration. Stilbenoid-enriched extracts have shown promising protection in vitro against various grape pathogens including downy mildew, powdery mildew, gray mold and wood diseases. Additionally, large-scale studies in vineyards reported a significant partial protection against downy mildew. Protection level is relative to the concentration of stilbenoids contained in the grape cane extract. Therefore, the huge varietal diversity of grape could be explored to select high-producing varieties for future use as biocontrol agent.