Pests that can carry a “death sentence” of a disease for citrus trees have been discovered near the Coachella Valley, prompting farming officials to expand a quarantine boundary near the area.

The Asian citrus psyllid is an insect that feeds on plant leaves. The psyllids sometimes carry a bacteria, Huanglongbing, that ruins fruit and kills the plant over time.

The California Department of Food and Agriculture confirmed Wednesday that the insect was found late last week in Desert Shores, about 14 miles from Mecca.

That means a quarantine boundary — one that would affect commercial citrus growers, ornamental nursery stock farmers and homeowners with trees in their backyards — is inching closer to the Coachella Valley.

“This thing multiplies like crazy,” Joel Nelsen, president of the California Citrus Mutual, said Wednesday.

“If we don't control this pest and the disease it carries, it will decimate the California citrus industry.”

None of the pests found in California have carried the tree-killing bacteria, but growers have been keeping an eye on the spread of the psyllid population since its arrival in Tijuana in August 2008, Nelsen said.

Insects have spread rapidly along major north-south highways since then, with quarantine areas now swelling to include parts of San Diego, Los Angeles, Imperial and Riverside counties.

For those who live and do business inside the quarantine area, extra precautions must be taken, according to Steve Lyle, public information officer with the California Department of Food and Agriculture.

Commercial citrus growers and packing houses must clean fruit stems and leaves.

Ornamental nursery stock, often used for landscaping, cannot be shipped outside of the quarantine area. It can be moved within the boundary only if treated with a series of insecticides first.

Residents with lemon, lime and orange trees are not supposed to take fruit and clippings outside of the quarantine area.

“Some people I talk to have anticipated it was going to be moving into the valley, that it was somewhat inevitable,” Marco DiMare of DiMare Co. said.

The company packages citrus for growers in the eastern part of the Coachella Valley and in Imperial County, where growers already are dealing with the added precautions and expense of the psyllid invasion.

DiMare said it costs an additional 50 cents per field box to clean fruit coming from within the quarantine area.

He knows of one packing house that spent $750,000 over nine months just on cleaning fruit.

“The production industry is under a burden. The nursery industry is definitely under a burden,” he said, “but the alternative is what's happening in Florida.”

That state has lost 200,000 acres of citrus to the disease. Nelsen said symptoms were found and preventative steps taken too late.

“I believe we've learned from those mistakes,” Nelsen said of the situation in Florida. “We're out ahead of it.”

Psyllids have a range of up to a mile and a half. They look for a food source — any kind of citrus tree, orange jasmine and Murraya plants.

The pest itself is difficult to detect. Nymphs are small and flatten themselves against twigs and leaves. Adults are about 4 millimeters and feed with their heads down.

The best thing homeowners can do is to check their trees often. If they discover an insect they've never seen before, they should contact their local agricultural commissioner, Lyle recommended.

Nelsen said the California Citrus Mutual is hopeful that a new home and garden product expected to hit stores as early as December could stem the spread of disease.

People would simply spread granules around the base of their trees and water. Once absorbed through the root system, the plants would have immunity against the disease, Nelsen said.