Legendary French wines were almost wiped out when the vines that produced their grapes withered in the nineteenth century. The problem was one that has become familiar; our capacity to ship species from one continent to another has meant that we can have much more variety in our plants and animals, but it also endangers the homebodies that have to meet the newcomers. In _The Botanist and the Vintner: How Wine Was Saved for the World_ (Algonquin Books of Chapel Hill), Christy Campbell writes that in the 1840s, trade in grape vines proceeded with "no barriers, no inspectorate, no concept of biological quarantine." The result was that tiny aphids with an extraordinary life cycle made their entry from America into France, and found the sap of the French grape vines exactly to their liking. Campbell has told the story of this disaster much like a mystery, and indeed, the vintners who saw their vines rapidly wither had no idea what was happening. A voracious caterpillar had threatened their plants two decades before, and a fungus had come shortly afterwards, but no one had seen a pattern of vine death like this one, with the leaves rapidly drying and curling up. There were only guesses about what was going on; too much rain, smoke in the air or iron in the soil from locomotives, and even emanations from telegraph lines were held to be responsible. Perhaps it was as simple as soil erosion or bad weather. No one knew.
The problem was an aphid usually called phylloxera. It took a long time to finger this particular culprit for many reasons, among which was that the tiny insect was not found on the dead vines. The simple explanation was that the aphids sucked all the sap they could out of the roots of the plant, and with nothing further to eat, moved on. Eventually, entomologists worked out the confusing life cycle of the aphid, which included several different forms of adults, some laying eggs on leaves, some laying eggs on the roots, and others having flying sexual forms. The aphids had been brought to France from America. The aphids and the American vines had long ago drawn a truce; aphids still infested the plants, but the plant developed mechanisms to keep alive through the assault, and the aphids settled in to feeding steadily off the living rather than killing the plants outright. The French vines had no such protection, so the aphids sucked them dry and moved on. Before finding an elegant solution to the problem, vintners simply had to pull up the dead vines and start growing something else, but that did not keep them from trying fanciful remedies, especially when the government offered a reward. Some proposed setting vials of holy water from Lourdes among the withering vines. Putting potatoes or frogs into the soil to draw away the poison had equal effect. Snail slime was championed, as were marching bands and a "beating wheelbarrow." Insecticides were useless. The problem had come from America, and the solution was from America as well. The solution was to use the root stocks of the American vines (vines which bore grapes the French considered vastly inferior), but to graft upon them the French vines which had been cultivated for centuries.
Campbell has told an enthralling story of science at work. It is a true success story, but attempts to control nature seldom result in total or permanent success. The final section of his book reveals that outbreaks continue to occur and that the insects can develop new strains to which the old solution does not apply. Perhaps the rootstocks can be immunized. Perhaps, in these days of genetic modification, the genes from American vines that co-evolved with the phylloxera could be somehow inserted into the French varieties. GM wines are probably inevitable. The wine world used its wits to battle one pest successfully a century ago, but there will be others, and the story is not all told yet.