Over a span of roughly forty years, from 1860 to the turn of the century, two émigrés from America first destroyed and then saved the great wines of Europe. The villain was phylloxera, the tiny yellow aphid that for so long had prevented Americans from growing vinifera grapes back home. The savior was American Vitis laBruce rootstock.

Phylloxera probably first came to France around mid-century. It crossed the ocean by steamship, perhaps lurking in the dirt on someone’s boots, more likely living along with other insects in a collection of nursery stock. It multiplied quickly, and its influence was first noticed in the southern Rhône Valley in the early 1860s. Previously healthy vines had suddenly stopped growing. The grapes did not ripen, the leaves turned brown, and after a few years the vines died. When the dead vines were dug up, it became clear that something had eaten the roots. But what, and why? Grapes had grown in these vineyards for hundreds of years. Why had the vines suddenly become susceptible to a plague of microscopic bugs?

It took ten years for that question to be answered and another ten for the answer to be accepted. By then it was too late. Phylloxera moved quickly—first to the Midi, then to Bordeaux, then north to the Loire, Burgundy, Alsace, and finally Champagne. It also munched its way through vineyards in Germany, Italy, and Spain.

Once people realized that phylloxera was an American immigrant, they also realized that American Vitis labrusca vines must have developed an immunity to it. The solution, then, was to graft Vitis vinifera plants onto American rootstock, and by the 1880s thousands of tons of American vine wood were being unloaded on the docks of Marseilles and Bordeaux.

The solution worked, but it brought a new problem, a fungus known as downy mildew that severely weakened the new vines and reduced yields dramatically. As soon as a grower saved his vineyard from phylloxera, he found himself subjected to this new scourge. Many could not survive economically, and all France was devastated. In nineteenth-century European agriculture only the Irish potato blight was a greater social and economic disaster.

Although there were still some vineyards to infect, the disease from America had just about run its course by the turn of the century. Its effect, however, lasted another lifetime. Phylloxera had virtually destroyed European wine, and the advent of two world wars, coupled with periods of severe economic crisis, made rebuilding extremely difficult. Not until the second half of the century did many of the old viticultural areas begin to enjoy prosperity again.

The story of phylloxera is not over. Nature protects its own, and a new strain has evolved that can destroy rootstock previously believed to be immune. Ironically, one of the most susceptible rootstocks, AXR1, was widely planted in California during the