California Vineyard sprays expensive pesticide.
Coachella Valley vineyards dodge disease bullet WINE: A pesticide, or the desert clime, may account for the absence of Pierce's Disease in the valley.
12/13/2001 By DON MCAULIFFE THE PRESS-ENTERPRISE All the pieces are in place for a devastating outbreak of Pierce's Disease in the vineyard-rich Coachella Valley. There are 14,000 acres of grapes, disease-spreading glassy-winged sharpshooters, citrus orchards in which to nest and a ready supply of bacteria that wiped out about half the grape vines in Temecula, according to recent estimates.
But the region's $150 million table grape industry so far has dodged the bullet that crippled Temecula's Wine Country and has growers as far north as Napa worried that they may be next.
"We have all the same things Temecula has," said Robert Bianco, co-owner of Anthony Vineyards in Coachella.
But the valley doesn't have grape vines that are dead or dying from Pierce's Disease, a plague that wiped out the grape business in Orange County in the late 1800s and more recently caused millions of dollars of damage in Temecula.
"It's a bizarre thing," said Bianco, who also is president of the California Desert Grape League, which represents about 18 Coachella Valley table grape growers.
"We have yet to find the disease in the field," said Vladmir Tudor, secretary of Tudor Ranch Inc., which grows table grapes on about 1,300 acres in Mecca.
Pierce's Disease is a chronic problem for California's wine industry. Each year it contributes to estimated losses of about $30 million, according to wine industry researchers.
But the stakes were raised about four years ago when Pierce's Disease was discovered in Temecula vineyards. This time the disease was being spread by the newly arrived glassy winged sharpshooter, a highly efficient transmitter that is a strong flier.
So far no one can explain the absence of Pierce's Disease among desert vineyards. An outbreak wiped out about 10 acres of vines in the desert about 30 years ago but it has not been seen since, according to area growers.
But scientists worry that it may be there already but just has not been detected.
"The current levels of GWSS (glassy-winged sharpshooter) in the desert coupled with the low incidence of PD signal the initial stages of the epidemic," University of California, Riverside researchers wrote in a paper presented at a Pierce's Disease symposium held recently in San Diego.
About 7,500 table grape vines this year were inspected for symptoms of Pierce's Disease. Of the 300 vines singled out for laboratory testing, however, none tested positive for the bacteria that causes the disease, researchers said.
"If (bacteria) levels are low, perhaps the test can not pick it up yet," wonders Carmen Gispert, an adviser with the University of California's Cooperative Extension, which is working with desert growers. "Pierce's Disease is present in the valley but in other plants."
Gispert said sharpshooter traps turn up one or two bugs a week. But that is far less than the thousands that were showing up in Temecula at the height of the outbreak.
Grower Mike Bozick thinks it may have something to do with the systemic pesticide grape growers began using about four years ago to battle another vineyard pest -- the vine mealy bug.
It so happens that the pesticide, known as Admire, also keeps sharpshooters from spreading Pierce's Disease in the vineyard, according to field tests.
"We think it has done a heck of a job," said Bozick, president of Richard Bagdasarian Inc., which farms about 4,000 acres of table grapes in Mecca.
It cost about $500 a gallon for the Admire that is applied twice annually, but he said it is just part of the cost of business.
Bianco also grows grapes in Kern County, but said Admire hasn't made much of a difference there. Admire was used in Wine Country, but only after Pierce's Disease had been discovered, industry officials said.
Others suggested that climate may play a role in curbing Pierce's Disease and the sharpshooter populations in the Coachella Valley.
Tudor of Tudor Ranch Inc. said extremes in desert temperatures are not ideal for crop-destroying insects.
"It makes it tough for a lot of pests and diseases to survive," he said.
In the meantime, Coachella grape growers are on the lookout for the sharpshooter and Pierce's Disease, which causes a vine to die of thirst.
"Because of what happened in Temecula, we are ahead of the curve," Bianco said.
Three years ago, he said three-fourths of the grape growers in the valley did not even know what Pierce's Disease was.
Today they are prepared and thankful for their disease-free vineyards.
"I wish I knew the answer," Bianco said.
Reach Don McAuliffe at (909) 587-3127 or dmcauliffe@pe.com
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