Growing Grapes: Phylloxera vastratrix

Wine has been around for thousands of years, but in 1863, catastrophe struck. French vineyards were infested by Phylloxera.

Phylloxera is a louse that attacks the roots of the grape, causing the leaves to fall off and eventual death of the plant. The bug had come from America where the grapes were resistant to the creature. Phylloxera spread quickly through much of Europe and would have been completely devastating, except that a "cure" was found. It was possible to take Vitis vinifera and "graft" it to American rootstock. The American rootstock was not affected by phylloxera and the grafted grapes were the European variety. Vines being dug up before burning

French grapes grow well in soil rich in lime. Native American grapes don't (and the wine they make is derogatorily described as "earthy" or "foxy"). American grapes were resistant to Phylloxera, the French grapes were not. Why not create a "hybrid" that has the best qualities of both? (You could grow the grapes from the hybrid, and this is done is some parts of the world, however most the desired variety of European grape onto the hybrid rootstock.)

There are many hybrids, but for California wineries, one particular hybrid rootstock seemed to stand out among all the rest: AxR #1. During the 1960's, wine grape planting in California took off. (Some farmers in the Napa valley saw their relatively inexpensive land soar to US $50,000 or so an acre. It's interesting to see the old farmhouses with the shiny new Mercedes parked in front of the homes of the luckier farmers--and no, I don't think all the Mercedes belong to transplanted doctors and lawyers.) AxR #1 was planted all over the place.

Unfortunately, it turned out that there were at least two types of Phylloxera, known as Biotype A and Biotype B. AxR #1 was resistant to the first, but not the second. Type B is now spreading like crazy throughout the state. While there are other rootstocks to chose from, many producers may not be able to withstand the cost of replanting and will close. (It takes five to seven years for new vines to produce grapes--too long to wait for many.)

The grower makes the decision on what stock to plant, but there are those who have heaped a fair amount of blame on the people at the University of California at Davis (UCD) for supposedly "pushing" AxR #1. It had been known by the French for at least 50 years that AxR #1 was not perfectly resistant. It would fail after 10 or 20 years in the ground. While AxR #1 has many good qualities, whether UCD did not make enough of AxR #1's shortcomings remains a controversial topic.