Leafhoppers wreak havoc on California vineyards

Leafhoppers known as glassy-winged sharpshooters are causing an outbreak of Pierce's disease in California vineyards    WINE 101: Message Board What our your favorite wines? Wine Labels Learn how to read them. Wine Prices Find out how much you'll pay. Wine Varietals Use our glossary. VIDEO CNN's Jim Hill reports on the leafhopper's impact on California vineyards Windows Media 28K 80K

September 12, 1999
Web posted at: 12:02 p.m. EDT (1602 GMT)

From Correspondent Jim Hill

TEMECULA, California (CNN) -- The harvest is under way -- plump, sweet chardonnay grapes have ripened to perfection.

But alongside the harvesters in Temecula, California, a destructive insect is hard at work, spreading a disease that leaves the grapes shriveled and useless.

"When the vine is severely affected, the fruit just dries up, and the fruit is not harvested," says grower Roberto Ponte.

The problem is a new and troubling outbreak of Pierce's disease, spread by a type of leafhopper known as a sharpshooter.

"Pierce's disease is a bacteria that plugs up the xylem tissue, or that duct which brings the water from the roots," explains grower Ben Drake.

Northern California vineyards lost $33 million in the last five years due to the disease. But the troubling aspect in Temecula is a new carrier called the glassy-winged sharpshooter. It's proving to be bigger, stronger and tougher than its cousins.

"We're finding it flying further distances out into the vineyards," says Drake, "so it's a much better carrier of the bacteria because it spreads it throughout the vineyard."

The insects carry the bacteria in their mouths, infecting the vine when they bore into it to suck out nutrient-laden water.

The disease does not infect people -- and perfectly good wine can be made from infected vines still able to produce grapes. But those infected vines live on borrowed time.

Insecticides and plant antibiotics have been proven ineffective against the disease

Experts in the grape-growing and wine-making industries say once the disease takes hold, it can destroy an otherwise healthy vine in one to three years.

One of Temecula's biggest wineries has lost 40 acres to the outbreak, leaving empty vine supports standing like grave markers.

Insecticides can't always kill the insects before they infect the vines, and plant antibiotics have also proven ineffective.

The disease appears to run in cycles. It was first detected in the 1800s, when it nearly destroyed the grape-growing industry in southern California. An outbreak in the 1940s cost the industry about $10 million.

Growers aren't content to wait for this latest outbreak to play out -- not with millions of dollars and their livelihoods at stake. Instead, they've asked for state and federal funds to research effective ways to stop -- or at least control -- the spread of the disease.

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