Prominent Lodi, Calif., wine grape grower Brad Lange spends too much money controlling vine mealybug in his northern San Joaquin Valley vineyards.
However, Lange is almost glad he is challenged to control vine mealybug, a pest rapidly establishing itself as public enemy No. 1 with California grape growers.
Vine mealybug is replacing the glassy-winged sharpshooter (GWSS) atop the list of vineyard bad bugs. Two years ago GWSS had California wine grape growers quaking in their boots. Lange said if GWSS establishes itself in his vineyards, he would not have to worry about vine mealybug because he would have not vines. He is happy all he has to worry about now is controlling the mealybug.
When the GWSS began vectoring Pierce's Disease in the Temecula area of Riverside County in Southern California and vines began dying, grape growers like Lange feared the worst.
Eventually Pierce's Disease wiped out half the vineyard acreage in Temecula within 3 years. GWSS carrying Pierce's Disease quickly made its way into the Southern San Joaquin Valley where it destroyed 400 acres of vines in Southern Kern County.
From there growers expected GWSS to march northward through the vineyards of the Central San Joaquin Valley and coastal premium wine grape growing areas like Patton roaring through North Africa.
However, it has not happened thanks to one of the most successful control and research programs ever undertaken in a California crop. GWSS has not been eradicated and Pierce's Disease is still around it to be vectored with one sure-death GWSS sting. All it takes is one GWSS sting to kill a grapevine. However, area wide control measures funded by the state and other sources have halted the northward March of GWSS.
GWSS has been found in Tulare County and is isolated area north of there, largely in urban areas. However, CDFA's rapid response to GWSS trap catches has prevented the insect from establishing itself in any vineyards as it did in Kern and Riverside counties before the eradication effort began.
The containment effort has been so successful that Lange, chairman of the Pierce's Disease and Glassy-Winged Sharpshooter Board, and others are afraid apathy and complacency could give the embattled GWSS new life to spread its venom like many predicted it would. The 15-member board Lange chairs advises CDFA on research and containment efforts funded by a wine grape growers' assessment.
When wine grape growers fully understood the threat PD/GWSS posed to the industry — recently valued at $45 billion to the state of California — they agreed to assess themselves to join the fight. So far more than $17 million in grower assessments have been collected to fund 100 research projects to find a cure or treatment for Pierce's Disease.
The legislative authority to assess growers expires next year and Lange and Bob Wynn, California Department of Food and Agriculture statewide coordinator for the Pierce's Disease Control Program, used the recent Unified Wine and Grape Symposium in Sacramento, Calif., to counter complacency in launching the get-out-the vote campaign for a May referendum to continue the assessment until 2011. The assessment is capped at $3 per hundred value of grapes crushed.
Wynn and Lange admit that the success of the program is breeding apathy, a dangerous attitude since both agreed the GWSS threat will likely never disappear from California vineyards. Only research and development to find a cure and perfect control strategies will keep it at bay.
Lange is so concerned that an out-of-sight, out-of-mind mentality will prevail among the 6,000 wine grape growers eligible to vote the May balloting that a required 40 percent turnout could be in jeopardy.
“I am concerned that growers will think that because of the success of the program so far that the battle has been won,” said Lange. “However, the threat of Pierce's Disease and the Glassy-Winged Sharpshooter will always be there for California grape growers. There is an absolute danger to the $45 billion wine and wine grape industry in this state.”
The grower assessment is only part of the millions that have been thrown at PD/GWSS to turn back the threat. To date more than $166 million in state, federal and grower funds have has been spent to control and research the problem. It has been an expensive battle, but to lose could spell the demise of the California grape industry. Pierce's Disease wiped out 40,000 acres of vines in the Los Angeles Basin in the 1880s. However, it has not been a major problem since then until GWSS arrived in California. Before the arrival of GWSS, Pierce's Disease damage had occurred in primarily “hotspot” areas.
GWSS arrived in California probably in the mid-1990s. It is a much more aggressive flyer than native sharpshooter and its host range is 100 species of plants. When GWSS infects a grapevine with Pierce's Disease, it clogs the vine's xylem, and the vines die from a lack of water. GWSS is so aggressive it will go down a vine row infecting plant after plant. There is no cure yet for it and while there are pesticides to kill GWSS, by the time it is detected in a vineyard vines have already been infected, destined to die.
While wine grapes are not the only crop threatened by GWSS/PD, Lange said wine grape growers had the most to lose and stepped up quickly to put money into finding a cure and treatment programs to prevent GWSS spread.
“More importantly, by assessing themselves, growers demonstrated their concern to government officials about the PD/GWSS threat, and we've been able to leverage those funds ten-fold with state and federal grants to help contain GWSS,” said Wynn.
If 40 percent of eligible growers vote, to pass it will require a yes vote of 65 percent of the growers representing the majority of the assessment or a majority yes vote and the yes voters must have paid 65 percent or more of the assessment that was paid by those who voted.
While Lange expressed concern about the voter turnout, he did acknowledge growers agreed to assess themselves the first time in 2001 when wine grape prices were very low. He is hopeful complacency has not diminished that support.
GWSS and Pierce's Disease also cause almond scorch, alfalfa dwarf, phony peach disease in peaches, plum leaf scald in plums and citrus variegated in chlorosis.
More than 100 plants host GWSS, but only a few are threatened by Pierce's Disease. GWSS also hitchhikes on ornamentals grown in Southern California and shipped north into the state's large grape growing areas. Wynn said the nursery industry has spent $10 million to monitor shipments, control the pest in nurseries and prevent the spread of Pierce's Disease into agriculture.
Wynn also added that there has been good support from the almond and citrus industries as well as raisin and table grape growers.
A bill was passed and signed into law at the last legislative session allowing creation of pest control assessment districts. Wynn said table grape growers in Tulare and Kern counties are “moving quickly” to form such a district to assess themselves in the fight against PD/GWSS.
While the focus has been on Temecula and Kern and Tulare counties where the largest infestations of GWSS have been identified, GWSS have been trapped in Ventura, Fresno, Sacramento, Santa Clara, Solano, Santa Barbara and Ventura counties.
Wynn said CDFA's ready response program designed to go into wherever GWSS are trapped and control the pest in urban areas before it can move into agricultural areas has contained the pest before it could be established in commercial vineyards.
The state also established a biological control program when GWSS first posed a threat. Wynn said it was an operational/research project that has proven very successful in using parasites to control GWSS in agricultural areas.
Wynn and Lange indicated they are heartened by the success of the program, but are concerned that success can breed apathy and possible reversal of that success if funding is not maintained for research and containment.
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