A grape-destroying bug lands on Monterey County's Most Wanted list.
Thursday, April 27, 2000
Reason to Wine
The glassy-winged sharpshooter doesn''t look like much of a threat. It doesn''t sting, it isn''t poisonous, and full-grown it''s just a half-inch long. But 10 years after it swaggered into California from the southeastern United States, the little outlaw pest has cinched its reputation as a big-time player in crop devastation in the southern half of the Golden State. And now farmers and agricultural commissioners in the rest of California, Monterey included, tremble at the sound of its name.
The problem isn''t the insect iself, but the bacteria it can spread. The glassy-winged sharpshooter is an alarmingly efficient carrier of Pierce''s disease, a blight that destroys crops by clogging the water transport systems in the stems of plants. Since the glassy-winged sharpshooter feeds on plants by sucking the sap from the stems, it''s the perfect delivery system for the Pierce''s disease bacteria. Although sharpshooters who don''t carry the Pierce''s bacteria are pretty harmless, those who do can lay waste a field in two years. The disease is incurable.
"It''s a big deal," says Corky Roche, a local vineyard consultant and chairman of a Central Coast task force to detect and prevent the spread of Pierce''s disease. "This is a huge threat, not just to viticulture, but to agriculture statewide. This pest is capable of passing the Pierce''s disease bacteria more than any other insect."
Help for counties trying to bar the entry of the glassy-winged sharpshooter could arrive as early as mid-May. On April 27, a bill to fight Pierce''s disease goes before the Assembly. Sponsored by Sen. Wesley Chesbro (D-Arcata), SB 671 would allocate $6.9 million per year for two years for the research, detection and control of the disease. It''s already passed in the Senate and garnered support from Gov. Davis. Its passage would help pay for expensive efforts in a state that has already seen plenty of destruction at the hands of the bacteria and its vectors.
The glassy-winged sharpshooter may be restricted to southern California, but Pierce''s disease isn''t. An indigenous cousin of the glassy-winged sharpshooter, the blue-green sharpshooter, has spread enough grief and Pierce''s disease in Napa County in the last few years to cost grape growers there an estimated $40 million.
But compared to its Florida-bred relative, the blue-green sharpshooter is a 98-pound weakling. It can''t fly nearly as far, it doesn''t reproduce as lustily, and because of its feeding preferences, it tends to merely damage plants rather than destroy them completely. It''s the glassy-winged sharpshooter''s ability to quickly colonize a field, rapidly reproduce and infect plants with deadly bacteria at a key point--in the cane--that makes it so worrisome to agricultural scientists.
"It''s definitely the Rambo of sharpshooters," says Roche. "It far surpasses all the other sharpshooters combined."
Crops that have suffered from Pierce''s disease include alfalfa, almond trees, citrus trees and oleander, but Pierce''s disease is best known for wiping out vineyards. Temecula County, for example, has lost half its wine grapes to the disease, which spread rapidly thanks to the glassy-winged sharpshooter. In Monterey County, where grapes are the fifth biggest crop, consuming 40,000 acres and yielding $179 million in revenue in 1998, that''s nerve-racking news.
The good news is that the glassy-winged sharpshooter hasn''t yet made an appearance in Monterey. In order to keep things that way, Monterey''s county agriculture office has adopted a proactive strategy intended to block the insect at its most likely points of entry: through shipments of ornamental plants from southern California nurseries. Bob Roach, chief deputy county agricultural commissioner, says his office''s biologists have spent hundreds of hours since October inspecting nursery shipments for signs of hitchhiking insects or eggs.
Other counties in the state, including Santa Cruz and San Luis Obispo, are doing the same thing, and Corky Roche says four of them have reported finding glassy-winged sharpshooter eggs in nursery shipments. Last week Monterey did too, although, Roche is careful to point out, it was an old dried-up egg mass, not a "viable" one.
"But it means that sharpshooters have been in that nursery, and that they''d been laying eggs," he says. So back the shipment went.
The county is not stopping at inspections. It''s also conducting detection surveys to make sure the glassy-winged sharpshooter hasn''t already worked its way into the county. That means setting out traps of sticky yellow paper in places where the insect might be, like recently landscaped parks that might have incorporated plants from infected nursery stock. It also means literally beating the bushes for the critter. Deputy ag commissioner Roach explains that on cold mornings it''s possible to lay a sheet on the ground beneath shrubs, beat them and count the bugs that fall on the sheet.
The detection survey is costly in terms of manpower and dollars--$335,000, by Roach''s estimate.
"We''ve been doing what we can," he says, "but this is a tremendous amount of work. We need to hire additional staff, and we can''t do that until funding arrives."
That''s up to the state Assembly and Gov. Davis. In the meantime, says Roche, a unified front among uninfested counties is necessary to success. "If it becomes established in an adjacent county to us," he says, "what we''ve done in our county won''t help much."
Staff intern Michael Edgecomb contributed to this report.