Deadly Vine Disease in California Draws Congressional Attention

Daniel Sogg
Posted: February 25, 2000

Facing a potentially cataclysmic threat to California's wine business, federal legislators have turned their attention to a fatal grapevine disease that has spread rapidly through the state. At a rare field hearing of the House Subcommittee on Livestock and Horticulture, industry leaders, scientists and government officials gathered in Napa Valley on Feb. 22 to consider how best to battle Pierce's disease.

The disease has already infected more than half of the 3,000 acres of grapevines in the Temecula appellation in Riverside County, costing the wine industry about $33 million over the past five years. In Napa, Sonoma and Mendocino counties, 8,000 of the total 78,000 acres of vines are infected. At present there is no cure for P.D., and infected vines must be torn up and replanted. Experts warn the disease, left unchecked, could devastate the $33 billion California wine industry.

"We're seeing vine-to-vine spread of Pierce's disease now," said Matthew J. Blua, research associate in the department of entomology at the University of California at Riverside. "That means its spread is exponential, not linear."

Caused by the bacterium Xylella fastidiosa, P.D. attacks plant tissue that transports water, killing the infected vine within three to five years. The bacteria can be transmitted by a variety of hosts, especially the glassy-winged sharpshooter, a leaf-hopping insect that has spread the disease with devastating rapidity because it can fly farther than other disease carriers. Researchers have identified more than 73 plants susceptible to P.D., including citrus and pit fruits, almonds and oleander.

The glassy-winged sharpshooter has not yet reached the vineyards of California's North Coast. Napa Valley is already hard hit by P.D., with one study putting last year's tab at $42 million, but that amount is a fraction of the damage that would result if the glassy-winged sharpshooter arrived in the region.

Industry experts say that $25 million is necessary to initiate the effort to contain the glassy-winged sharpshooter and eventually find a cure for P.D. At present, only $350,000 of federal funding has been allocated.

While Rep. Richard Pombo, R-Calif., chairman of the subcommittee on livestock and horticulture, suggested that obtaining initial funding of $25 million is unlikely, he anticipates prompt federal action. "My expectation is that we'll have a budget line item to deal with this problem," he said. "We'll probably have to start with a smaller number and work our way up to $20 or $25 million."

Read past news reports about the spread of Pierce's disease: