Vitis vinifera vines grown pretty much everywhere in the world are now grafted vines. Native American grape species became necessary after phylloxera was inadvertently introduced to Europe in the mid-1800s from plant materials originating from the New World. Phylloxera decimated vineyards with V. vinifera roots but native American grapes were resistant to the insect. In modern times, this continues to be an issue, as we saw in the ‘90s when a purported new biotype of phylloxera attacked th...