Rootstock Mix-Up Raises Fears Among California Growers

Jeff Morgan
Posted: June 14, 1999

Growers in California's North Coast appellation have received an unpleasant surprise: A researcher at the University of California at Davis has discovered that some vineyards thought to be planted with a rootstock resistant to the deadly vine louse phylloxera may have been accidentally planted with a different, less resistant rootstock.

The situation is reminiscent of the crisis that began in the mid-1980s when AxR No. 1 rootstock, which had been widely planted in California vineyards over the previous decades, proved to be susceptible to phylloxera attack. AxR No. 1 was popular among many growers because it was resistant to grapevine diseases and tended to produce large crops of grapes. The rootstock's demise resulted in widespread and costly replanting that is still occurring throughout the state today.

Fortunately, the latest scare is on a much smaller scale. "Only a small percentage -- maybe 5 percent -- of the North Coast vineyards might be affected," said Deborah Golino, director of the Foundation Plant Materials Service at UC Davis.

Golino explained that two nearly identical rootstocks, 039-16 and 043-43, were used in the 1980s because of their resistance to a grapevine disease called fanleaf virus. Eventually, 043-43 proved to be less resistant to phylloxera than 039-16 and was discontinued. However, because of its nearly identical appearance to 039-16, some nurseries mistakenly continued to propagate and sell it.

"There is nothing a grower can do now," Golino said. "Even in a worst-case scenario, they'll have to manage their vineyards for the vines that are fine and not those that are bad." She believes a few growers might be at high risk -- though she wouldn't mention any names -- but that most have only a small number of vines affected. She concluded, "I don't see this as an urgent problem."

To learn more about the problem of phylloxera and its effects:

April 30, 1999
Phylloxera Spreads Across Oregon Vineyards

December 7, 1998
Unfiltered, Unfined: Bugging Out

February 9, 1998
Next Martha's Vineyard Release Not Until 2001

October 31, 1995
California Vintners Struggle to Preserve Genetic Heritage of Historic Vineyards

September 15, 1995
Santa Barbara Joins the Phylloxera Hit List

September 15, 1995
Grape Supply Tightens in California and Bottle Prices Could Soon Rise

April 15, 1995
UC Davis Facility to Help California Clean Up Vineyards