The 411 on Phylloxera

Daktulosphaira vitifoliae

Grapevines, like all living things, are subject to disease and other pests. One of the most problematic for vineyards, as the world discovered in the 19th century, is phylloxera.
Phylloxera is a sap sucking microscopic louse that is originally from the northeastern states. After years of exposure, the native grape species became resistant to it; however, the vitis vinifera, or European grapes, are not.
When phylloxera strikes, it eats the roots and leaves of vines, which can deform vines so that they do not get nutrients or water, and injects deadly venom into the roots of vines. This might sound like a horror movie, but if you think about the level of destruction it has caused over time, horrific might be an understatement. It moves from leaf to leaf and can be transmitted by wind or transported by foot, and there is no way to kill it or prevent its proliferation.
Phylloxera was brought to Europe by English botanists in the 1850’s who traded rootstocks with American growers. It was first recorded in Provence in 1863 but its presence was known as early as 1858. Over the course of 1860’s and 70’s, it spread not only throughout the continent but also to other parts of the world, afflicting vineyards in Napa (where European grapes were being grown). Once the cause was discovered, two French growers suggested that the European vines be grafted to the resistant American rootstock. In 1871, the first American rootstock was imported from Texas. By the 1880’s phylloxera was brought under control, after destroying anywhere from 40% – 70% of the Europe’s vineyards.


A grape leaf infested
with Phylloxera”

To this day, grafting to resistant rootstock is the only way to prevent it. Hybrid rootstocks were created such as AxR1, which has its parents, St. George, an American species, and Aramon, a vinifera cultivar from the south of France. The problem is that the latter turned out to be non-resistant, which California painfully discovered in the 1980’s and 90’s. In the 60’s and 70’s when many vineyards were planted, AxR1 was the recommended rootstock and for the first 20 years it worked but eventually, it proved to be non-resistant. The growers that used St. George rootstock instead were saved and another hybrid rootstock, “41b,” so far seems to be effective.
In total the phylloxera outbreak in California, which hit epidemic proportions in 1992, spread to at least 50,000 acres of vineyards in California, mostly in Napa and Sonoma. It cost upwards of six billion dollars in damage. While that crisis was brought under control by the Millennium, another one loomed… Pierce’s disease.

Be sure to sample some of the wines that survived at Golden Gate Wine Cellars!