A quarantine will take effect in Tulare County next week to thwart a pest threatening the citrus industry, the California Department of Food and Agriculture said, and growers in Kern County are closely watching what happens.

State officials said this week they're still determining the size of the Tulare quarantine area, something they should settle by next week.

But Dave Cox of Visalia, chairman of the California Association of Nurseries and Garden Centers, said he expects the quarantine zone to be a 20-mile radius around Strathmore, near where the Asian citrus psyllid was found.

The quarantine affecting fruit and nursery trees is being imposed after an adult psyllid was discovered in an insect trap near Strathmore.

The bug can spread citrus greening disease that kills trees.

Oranges and other citrus produce can be moved out of the quarantine zone only if it has been commercially processed, while fruit from backyard trees in the zone must stay on the property, said state Food and Agriculture spokesman Steve Lyle.

If the quarantine zone does extended to a 20-mile radius, then Kern County growers should not be affected, said Louie Cervantes, assistant director of the Kern County Department of Agriculture and Measurement Standards.

Kern County is waiting to see what it should do until the quarantine is set, Cervantes said. Next week, the county will begin talking about the possibility of starting spraying programs or laying out more traps for the pests.

Though the psyllids were found in Tulare County, Kern citrus growers are worried for their crops.

Ben Taft, manager of California Citrus Depot in Edison, said the bugs are likely to make their way to Kern County by being carried on the wind.

"It's a bug. To say we're going to put up roadblocks or try to do anything, Mother Nature will push it around," he said.

Dick Minetti, owner of Minetti's Anxious Acres in east Bakersfield, said he has allowed various government agencies to lay out traps on his land, so he feels a little protected from the psyllids.

Still, Minetti said, he's worried about the pest ruining his fruit and Kern County's citrus industry.

"If it hits here," he said, "it's going to be rough."

Growers in the quarantine zone can survive because packinghouses will process fruit for shipment, but the biggest effect is likely to be on nurseries that grow trees for sale to farmers or garden centers. Unless the trees are grown in insect-proof enclosures, they can't be moved out of the quarantine zone, said Tulare County Agriculture Commissioner Marilyn Kinoshita.

For nursery owners, "it's like a punch in the stomach," said Leonard Massey, general manager of B&Z Nursery in Porterville, which grows trees for orange farmers up and down the valley and is inside the expected zone.

Most nurseries don't grow trees bound for market inside insect-proof enclosures because they're expensive and not required by law, Massey said.

B&Z has one such enclosure for trees going to market, but that structure has yet to be signed off under U.S. Department of Agriculture regulations, he said.

Nursery grower George McEwen of Lindcove said it appears he'll be in the zone, and he's dreading its effect on the 50-year-old family business

"That's going to be devastating," McEwen said. "I'm not fully screened."

He said his first and second-generation trees are in screened greenhouse as required by state law, but not his trees being grown for market.

Grower Greg Kirkpatrick of Lindcove said it's likely that the Kirkpatrick citrus ranch will be in the zone. The farm grows specialty trees and sells the leaves as flavoring agents. Fruit can be processed and shipped in a zone but not the leaves, he said.

"I called one of my customers and said, 'You better get some quick before they impose the zone,'" Kirkpatrick said.

The bug was found last month in a commercial orange grove. The specimen was so dried out it couldn't be tested for the presence of the Huanglongbing, or HLB, the bacteria carried by the Asian citrus psyllid, officials said.

State Food and Agriculture inspectors have been checking trees in the area where the bug was found but have not detected citrus greening, said Lyle, the agency's spokesman.

Bob Blakely, director of industry relations with California Citrus Mutual, an orange growers' lobby based in Exeter, said Tuesday that because only one bug has been found and there's no evidence of disease, a quarantine is not warranted. He said Citrus Mutual has tried to make that case in phone calls to state officials.

Although only one bug was found this fall, another was found in a trap near Lindsay in February, prompting the state to proceed with a quarantine, Lyle said.

The quarantine will be ended in two years if no more psyllids are found, he said.

-- Californian staff writer Rebecca Kheel contributed to this report.