Phylloxera: Tiny Pest, Huge Impact




In the late 19th century, an insect commonly referred to as phylloxera, spread throughout Europe destroying every vineyard in its path, and then made its way to South Africa, Australia and New Zealand, continuing its rampage. At the time it was thought to be the biggest disaster in the history of wine, but with hindsight, some believe it was a blessing in disguise.

Grapevine phylloxera is a species of plant lice 1/30 of an inch long and 1/60 of an inch wide. It is native to America, but indigenous American grapevines, having evolved in the presence of the louse, have developed immunity to the pest. Native European grapevines, however, are susceptible to the insect. In the 1860s, when native American vines were taken to Europe by botanists, phylloxera went along for the trip with disastrous results.

Many treatments were tried unsuccessfully, and some attributed the blight to the wrath of God. Many thought the world’s vineyards were doomed and wine would cease to exist. By 1873, the situation was so dire that the French government was offering a monetary reward to anybody who could come up with a way to end the blight.

Finally, Emile Planchon, a French botanist, recognized that insects on the roots of the vines were the cause of the problem, and he discovered that American vines were immune to the parasite. In the 1870s, he worked with Charles Riley, who was the state entomologist of Missouri, and they developed the solution—the grafting of European vines onto American vine rootstock. To this day, this is the only way to render the parasite harmless. Today, much of the world’s wine comes from vines growing on American roots because vineyards around the world were uprooted and replanted on American rootstocks.

In the 1980s, a different genetic strain of phylloxera appeared in Napa Valley. It attacked a specific type of American rootstock planted throughout California in the 1960s and 1970s, which was susceptible because one of its parents was a European variety. By the 1990s, this new type of phylloxera had spread to Washington State and Oregon. Replanting cost millions.

So what’s the silver lining? When vineyards were replanted, varieties and rootstocks better suited to each site were used. By the 19th century, growing demand for wine from Europe’s great wine regions had resulted in vineyards being established on poorly suited land and the introduction of inferior grape varieties. Due to the considerable expense and effort involved with grafting and replanting, much needed rationalization took place—only the best sites were replanted and the best vines were cultivated.