Caution is giving away to guarded optimism as vineyard owners replant vines in ravaged Temecula Wine Country.

"We are all still holding our breath but we are optimistic about what we see," said Mike Rennie, who manages and grows grapes on about 400 acres in Temecula.

Growers are pulling out dead and dying vines infected with bacteria that cause Pierce's Disease and replacing them with new grape varieties that are more resistant to a vineyard scourge that wiped out grape farming in Orange County more than a century ago.

Earlier this year veteran winemaker Joe Hart replaced nearly 1,700 vines in his 11-acre vineyard.

The new plants filled the unsightly gaps, or skips, created when sick plants were removed from the rows of vines that overlook Rancho California Road at the entrance to Temecula's Wine Country.

Hart, also president of the Temecula Valley Winegrowers Association, said the "fair amount of replanting" taking place in Wine Country this year is a positive sign that counters what the doomsayers had been saying about Temecula's uncertain future as a wine-making region.

After losing about a third of its vines to Pierce's Disease, Callaway Vineyard & Winery is considering limited replanting,

Temecula's biggest winery may plant red varietals on 12 of the approximately 220 acres left barren by Pierce's Disease.

The decision to replant depends on approval of a final budget but the fact that Callaway is even considering replanting represents a turnaround from a year ago.

"Last year at this time we were not even thinking about it," said Craig Weaver, vineyard manager at Callaway, which grows grapes on about 700 acres in Temecula.

In the past three years agricultural experts have discouraged Temecula growers from replanting because no one knew what Pierce's Disease would bring.

Now for the first time since Pierce's Disease was discovered in Temecula, ag officials recommend that Wine Country growers test the waters by replanting about 2 percent of the dead vines over each of the next several years.

"I'd replant some if you are serious about running a winery," advises Raymond Hix, extension specialist and entomologist with the University of California, Riverside.

Throughout Wine Country, large growers and small feel confident enough about the region's future to reinvest in their vineyards.

But replanting is not cheap. It can cost $10,000 to $15,000 an acre to plant a new vineyard. The price tag can go even higher depending on irrigation system, trellising to support the grape-laden vines and the variety and quality of vines.

Growers are retesting the waters after a federally funded insecticide spraying program dramatically reduced sharpshooter populations in the Temecula area.

For the second year in a row, citrus orchards in Wine County were given a double dose of insecticides that knocked off sharpshooters that lived in the lemon and orange trees during the winter months.

"The good news is the sharpshooter populations in Temecula are very low this year," said Hix.

He estimated that sharpshooter counts are down 88 percent from a year ago.

The bad news is that any sharpshooter in the vineyard poses a threat of infection.

"There is no tolerance for this bug in the vineyards because one is capable of spreading the disease," he said.

There is no cure for Pierce's Disease, which causes a grapevine to die of thirst.

Along with the lower sharpshooter population, the number of vines infected with the bacteria that causes Pierce's Disease is down sharply from a few years ago.

Dave Granlund, who grows grapes on about 21 acres, watched the infection in his vineyard peak at 70 percent about two years ago.

His vineyard was about a quarter mile from where Pierce's Disease was first discovered in Temecula in 1997.

Today, Granlund is heartened that the infection rate has plummeted to a more manageable 1 percent to 5 percent.

"Economically we can survive that," he said.

There's even talk about sprucing up the vineyards that line the entrance to Wine Country.

"It's important that we keep up appearances at our front door," said Ben Drake, who oversees about 250 acres of grapes for himself and clients.

Temecula grape growers won't know how much damage Pierce's Disease caused this year until after harvest. But damage through the end of the last year was estimated at about $9 million.

One of the reasons for grower optimism may be the mild spring and summer. Grapevines typically don't exhibit Pierce's Disease symptoms until they are stressed, such as during hot weather.

As temperatures sizzled past the 100-degree mark in early August, growers noticed a pickup in classic Pierce's Disease symptoms as grape bunches shriveled and leaves turned brown, a condition known as leaf scorch.

When growers replant it's ABC -- Anything But Chardonnay. Chardonnay, which accounts for about 60 percent of the vines in Temecula, is most susceptible to the bacteria-carrying sharpshooters.

Syrah and petite bordeaux are popular choices among Rennie's clients, who are pulling out 25-year-old chardonnay vines in favor of hardier, more PD-resistant and marketable red varietals.

Accelerating the switch is the glut of chardonnay. After a statewide bumper crop last year, many Temecula growers left grapes hanging on the vine because they were uneconomical to pick.

"The Temecula Valley has overshot its demand for chardonnay," said Dan Atwood, Temecula car dealer who owns a 5-acre vineyard in Wine Country.

Growers are hoping that enough of the new vines will survive. To ensure their viability, the young vines are treated with a systemic insecticide called Admire that discourages sharpshooter feeding and makes the bugs more lethargic.

But the cost of treating the vineyard with the insecticide is about $200 an acre, nearly the same as the cost to irrigate the acre.

Right now the hopes of Wine Country lie in a series of wintertime insecticide programs to knock down sharpshooter populations in the citrus groves adjacent to the vineyards.

For each of the past two years the U.S. Department of Agriculture has set aside about $300,000 in emergency funds to battle the sharpshooter in Temecula.

Winemakers worry that this year's rush to replant and newfound grower optimism will cause those in charge of the money to take Temecula off the critical list.

Even as tourists and the wine industry acknowledge that Temecula is not dead, growers fear that too much good news will cause important federal funding to dry up.

"If we lose USDA finding we are back to where we were," warns Drake.

The balancing act has Temecula growers walking a fine line.

"Alarm bells have to be ringing but not to the point where it scares people away," said Hart.

Don McAuliffe can be reached by e-mail at dmcauliffe@pe.com, by phone at (909) 587-3127, or by fax at (909) 676-9232.