Winemakers Worry as Bug Eats Acres of Prime Vines : Environment: Some California growers are replanting as they search for ways to stop phylloxera’s spread.

Wine scientist Pat Henderson knew that the inevitable had caught up with Kenwood Vineyards when he saw the stunted vines at the winery’s prized Yulupa Vineyard near Sonoma.

The phylloxera--a minute, aphid-like bug that is killing acres of grapevines in the Napa and Sonoma wine country by devouring their roots--had attacked the spot where Kenwood grows grapes for a popular Chardonnay.

Though only a few vines in the vast field are distressed, Henderson knows full well that, given time, the voracious pest can wipe out the entire vineyard.

“The solution would be to cut everything down, fumigate and replant, but we would lose production,” Henderson said. “We’re looking at ways to soften the impact. We don’t want to panic.”

Throughout the wine country, the phylloxera invasion has caused a viticultural revolution as anguished growers and vintners--many of whom deluded themselves for years that their vineyards would somehow be impervious--struggle to devise ways to beat the bug without devastating all their lush vineyards in the process.

Already, more than 2,000 acres of vines have been ripped out and burned, with growers replanting phylloxera-resistant rootstocks at enormous cost in cash and lost production. In an effort to avoid starting over, many growers are experimenting with relatively unproven methods--planting new vines between existing rows or next to existing vines--in the hope of preserving their yields.

By one estimate, 70% of the nearly 70,000 acres of vineyards in Napa and Sonoma, which produce California’s prized premium wines, will eventually be replaced, at a cost of at least $1 billion. That is a hefty price tag for a region that accounted for an estimated $2.5 billion of the $7 billion in retail sales of California wine last year.

The replanting is expected to lead to a decade-long drop in grape supplies that, under normal circumstances, might dictate that wine prices would soar. But given the recession and hefty stocks of wine in warehouses, it is unlikely that vintners will be able to boost prices soon.

This latest bugaboo is another blow to California’s beleaguered farmers, who in the last few years have been beset by drought, freeze and whiteflies. But for Napa and Sonoma growers, who were spared most of the ravages of those scourges, the phylloxera shapes up as the challenge of a lifetime.

“This is a very in-your-face pest,” said Rhonda Smith, the farm adviser in Sonoma County with the Cooperative Extension Service, run by the University of California. “For the individual grower, this is probably the worst thing that he or she is going to confront.”

In recent years, California’s high-profile premium-wine industry has had to cope with the recession, health concerns, heavy inventories and other challenges. Some vintners and growers suspect that phylloxerae could weed out weaker operations that have already borrowed heavily to survive.

Yet the more optimistic of the wine-making set note that the phylloxera infestation has goaded growers into experimenting with new planting methods that promise higher-quality, higher-volume yields down the line.

The phylloxerae afflicting the California wine country is a variation of a pest that in the late 1800s wiped out the vineyards of France before munching its way through the rest of Europe’s grape-growing country.

The insect, which reproduces at a rapid rate and spreads underground through vineyards’ vast root systems, dines on roots, eventually causing leaves to discolor, fruit to shrivel and vines to die. In the 1800s, growers unwittingly passed infected plants around the world. By the turn of the century most of the vineyards of South Africa, Australia, New Zealand and, ultimately, California had been destroyed.

After decades of devastation, European viticulturists devised a solution: Graft plants onto resistant roots from America. To this day, most European wines come from vines grafted onto American rootstocks. (When it was California’s turn last century to have phylloxerae, Europe returned the favor by supplying rootstocks developed from those resistant American varieties. The same thing is recurring to some extent this time around.)

The problem in Napa and Sonoma is that the current, more aggressive phylloxera--dubbed Biotype B when discovered a decade ago--attacks the AxR1 rootstock that is prevalent in those counties and was immune to the original strain. AxR1 was heavily promoted by UC Davis decades ago as the best rootstock for Napa and Sonoma--even though researchers knew that it had proved vulnerable to the phylloxera in other countries. Growers grouse now that the downsides were not adequately emphasized--or that they simply did not heed the warnings.

“The recommendation was made with lots of data,” said Jeffrey Granett, a professor of entomology at UC Davis and a member of an informal Phylloxera Task Force. “Over the years, it served the industry well--and might have saved the industry from some other problems.”

But Granett and others acknowledge that UC Davis erred in being complacent and not continuing to select and breed improved rootstocks that might have kept this new strain at bay.

For a long time after Biotype B hit Napa Valley in 1987, the effects were scarcely noticeable. Many growers, despite being made aware of the phylloxera by UC scientists, went through a denial phase that cost valuable time. But visitors driving along the highways that bisect the wine country can spot acres of freshly planted vines, many of them little more than sprouts, their bases covered by colorful milk or juice cartons to protect them from varmints. The devastation spreads in a radiating pattern that is even more obvious from the air.

Not so obvious are experiments such as those under way at the vineyards of the giant Robert Mondavi Winery in Oakville in the Napa Valley. Of the operation’s 1,300 acres, 700 are planted on the sensitive AxR1 rootstock.

Trying to turn phylloxerae to its advantage, Mondavi’s vineyard experts are taking the costly approach of replanting more vines per acre--as many as 2,500 compared to the current 450--by narrowing the distance between vines and rows. They are also using a variety of rootstock that they are attempting to match to the most suitable soils and microclimates. Many vintners are trying to look on the bright side: It’s an unexpected chance to create customized fields of dreams.

“The 700 acres of AxR1 will eventually need to be replanted,” said Phil Freese, vice president of wine growing. “It’s a matter of when, not if.” The price could reach $25,000 an acre. Even the mighty Mondavis are finding that bankers, already beset by troubles with commercial and real estate loans, are being “very careful” about lending for phylloxera-related replanting, Freese said.

“We’re getting very aggressive about replanting so the vineyards will recover quickly,” Freese said. “What we’re trying to achieve with higher-density vineyards and (different) rootstocks . . . is to decrease the amount of fruit per vine but enhance the yields.” Over time, the winery hopes to recoup the additional investment, but Freese noted that that is far from a certainty.

Vintners and growers are often making costly decisions based on precious little information. Mondavi, for one, plans in 1993 to take a break from its recent hectic planting pace to evaluate which plantings are thriving and which are not.

“All this stuff is going by at light speed,” Freese said. “We want to stop and get caught up.”

So far, Sonoma County has not been hit as hard as Napa. Grower George MacLeod, of the hillside Indian Springs Ranch near Kenwood, recently found one acre of affected vineyard and is “debating vigorously” with his four co-owner children what route to take.

“All growers are struggling with the implications of these sudden expenses,” said MacLeod, who is president of the Sonoma Valley Grape Growers Assn.

At 71, MacLeod had planned to gradually turn over the 50-acre operation to his children, but the phylloxera outbreak, he said, “means I have to do a lot more work in the next few years than I planned.”

In many cases, MacLeod noted, vintners are delighted with the chance to try new varieties of grapes. But in his case, both he and the company that buys his grapes, Kenwood Vineyards, are happy with his Zinfandel and Sauvignon Blanc grapes.

“Most growers have a really intense relationship with their vineyards,” he said. “Something like phylloxera . . . is quite traumatic and emotional.”

Henderson, the enologist at Kenwood Vineyards in Sonoma County, said he fears that phylloxerae will put pressure on beleaguered growers to turn over their land to housing developers. Agricultural land is protected to some extent in the region, but Henderson nonetheless is far from sanguine.

“That’s what I’m more worried about than anything else--taking the land out of production,” he said.

If all the attention to improved rootstocks and new planting technologies pays off, these dream vineyards are expected to create a tremendous growth in supply after the turn of the century, according to Motto, Kryla & Fisher, a wine industry consulting firm.

In a recent study, the firm projected that the replanting will cause grape production to fall off rapidly from the 1991 record of more than 283,000 tons. Production is expected to bottom out in 1997, then scoot back to a record 380,000 tons in 2006.

What this will mean for wine prices is anybody’s guess. The premium-wine segment of the market has shown healthy growth in recent years, but the recession and other factors have forced vintners to keep a lid on prices.

“It’s hard to project demand for a consumer product,” said Vic Motto, a partner in the firm.

Meanwhile, vintners and growers are pushing for renewed emphasis on phylloxera research. The problem is that UC Davis and other schools are struggling with budget cuts, and agricultural research and development are getting shorter shrift.

“The state is so strapped for funds that individuals are doing the R & D,” said Jack Cakebread, owner of Cakebread Cellars in Rutherford.

Rising to the occasion, some California winemakers have organized their own blend of Woodstock and Farm Aid. “Rootstock” is planned for Sunday in Napa, with wine and food enthusiasts paying $75 each to eat, drink and be entertained.

“Ultimately, the consumer pays (for research costs), so why not go directly to the consumer and have them send money to Davis,” said Michael Martini, winemaker with the Louis M. Martini winery in St. Helena. The festival will also give Martini a chance to play guitar in his rock ‘n’ roll winemaker band, Private Reserve.

The Phylloxera Outbreak

The spread of phylloxera, a minute bug that dines on grapevine roots, has forced Napa Valey and Sonoma County grape growers to pull out many acres of vines and replant. Starting this year, a lengthy dip in grape supplies is projected.

Grape Supply (in tons) 1978: 137,697 1992: 272,034 2006: 380,000

The aphid-like phylloxera is a variation of a pest that wiped out most of France’s vineyards in the 1880s. The adult bugs are exclusively females that can lay as many as 300 eggs in a lifetime. All the eggs develop into females as well, so that the numbers quickly grow. The pest spreads in a circular fashion, radiating out from the initial site by crawling underground through the root system. Under certain circumstances, some of the crawlers grow wings. The winged forms crawl to the surface and fly or get blown significant distances. Phylloxera can also be carried on tractor tires or workers’ boots.

Source: Motto, Kryla & Fisher; University of California Cooperative Extension