Nurseries’ Growing Arsenal Is Bringing Down Sharpshooters

Southern California nursery owners are gaining the upper hand in their fight against the voracious glassy-winged sharpshooter, with aggressive inspections and new pest control measures slowing the spread of the farmland scourge.

Nursery operators from Santa Barbara to San Diego have worked in recent years to reduce the number of shipments rejected for carrying the sharpshooter, a disease-spreading predator considered a major threat to California’s $14-billion wine industry.

Every county in Southern California is infested with the needle-nosed insect, and nurseries in those areas must submit trees, shrubs and other greenery to intensive inspections before they can be shipped to the upper half of the state. Those checks are aimed at safeguarding the region’s valuable winemaking operations. When shipments bearing any sign of the sharpshooter arrive up north, they are sent back at the nursery’s expense.

But records show that there have been fewer problem shipments each year since an aggressive inspection program began a little more than three years ago. Of 65,000 nursery stock shipments to Northern California last year, authorities there rejected only 40 nursery flats, compared with 77 rejections in 2002 and 151 the previous year.

“That’s phenomenal success,” said Robert Crudup, president of Calabasas-based Valley Crest Tree Co. and a member of a statewide task force that is battling the sharpshooter’s spread. “We’ve been doing this now for three years, and we’ve just gotten better at it.”

Unlike other pests that feed on fruit, the sharpshooter does its damage by delivering a bacterium that causes Pierce’s disease. The disease clogs water-carrying vessels in plants and starves them of nutrients until they whither and die. Grapevines are particularly susceptible, although the malady also strikes almond trees, oleanders and other plants.

The disease has plagued agricultural areas for more than a century, but the arrival of the aggressive, fast-moving sharpshooter accelerated its spread.

The worst damage has occurred in Temecula, where 1,000 acres of wine grapes have been destroyed in recent years, costing growers $40 million.

As part of the ongoing effort to prevent the pest from moving into other winemaking regions, state regulators have placed a range of restrictions on the $3-billion nursery industry, including hand inspections of every leaf of every tree, plant and bush sent from an infested county to Northern California.

It is painstaking work. On the front lines of the battle in Ventura County, nursery workers check shipments before summoning a county strike force created to hunt down the bug, which may be associated with as many as 400 types of plants.

The 15-member county crew is called just before a shipment is to be sent up north. The team is responsible for inspecting two dozen nurseries and averages six a day.

At a nursery near Moorpark last week, workers thumbed through magnolia plants and waded through giant palm fronds, scouring the underside of each leaf for telltale signs of sharpshooter eggs. If inspectors find a couple of egg masses, they destroy them and certify the load. But if they find too many, they stop the inspection, have nursery workers go through the load again and arrange to return later.

The insect detection program, begun three years ago with a $650,000 annual state grant, has paid dividends. As many as 60 loads from the county’s nursery operators were rejected in the early years, compared with just seven all of last year.

But that isn’t to say the bug has been beaten.

“Look where we’re at now -- surrounded by citrus and avocados, even native plants,” said program supervisor Rudy Martel, a senior inspector for the county agricultural commissioner. “The majority of our nurseries are situated like this, and these areas are just prime for this bug.”

It’s not just inspections that are shrinking the sharpshooter’s presence. Cooler weather, pesticide treatments for nurseries and surrounding citrus groves and the statewide release of parasitic wasps -- a natural sharpshooter enemy -- have helped reduce the insect’s population.

There is even speculation that last year’s wildfires played a part in reducing pest pressures, destroying thousands of acres of vegetation where the sharpshooter feeds.

Efforts to control the pest have been aided by $37.5 million in state funding and $87 million in federal funding over the last 3 1/2 years. Even wine grape growers are taxing themselves -- $2 per $1,000 of crop value -- to support the struggle against the vine-killing insect.

The money has paid for everything from research to reimbursement for nursery owners who have lost money because of the state-mandated restrictions.