It was just two years ago that the first Asian citrus psyllid was discovered in Tijuana, Baja California.

The find sent alarms through the California citrus industry, because the psyllids can carry the bacterial disease huanglongbing.

Then the situation got worse.

Psyllids were soon found in a San Diego suburb. More of the pests were detected a month later about 100 miles east of San Diego. Within a year, infestations were confirmed as far north as Los Angeles. 

Aware that the pest and the disease had decimated thousands of acres of Florida groves, panic began to simmer just below the surface of the California citrus industry.

Grower-shippers responded by increasing assessments to fight the pest.

Today, there is guarded optimism.

“With the new varieties out there, I’m encouraging people to plant,” said Ted Batkin, president of the Citrus Research Board, Visalia, who has spearheaded the industry’s comprehensive plan against the psyllid.

Efforts appear to have halted the pests’ move north, keeping it out of the San Joaquin Valley, the state’s major citrus growing region.

While spraying has been effective in greater Los Angeles, Batkin said more must be done.

“It’s just such a large area that it’s a resource intense treatment program,” he said.

The industry is working with the U.S. Department of Agriculture and the California Department of Food and Agriculture to track infestations, with grower-shipper assessments.

“We’re going to raise nearly $10 million in assessments this year, and it will be higher next year,” Batkin said.

To keep the psyllids in check, trapping at a higher density rate has been initiated in urban areas.

“The concern is we’ve seen this pest move in the urban populations,” Batkin said. “So, if we’re not looking there, it could sneak in on us.”

The strategy is to hold the pest in Southern California even as more traps are being used in the San Joaquin Valley, he said.

There have been some setbacks. Though treatments in San Diego County have been effective, infestations have turned up again in Imperial County. Batkin said it is not clear whether the new discoveries came into California from Mexico or were near, but outside, the areas treated previously. As a result, all spraying now is applied to everything within a 400-meter-radius of traps found to contain psyllids.

An industry-owned and operated lab in Riverside — an hour’s drive east of Los Angeles — has the staff and capacity to test up to 10,000 samples per week, Batkin said. Because it is used to test for many other commodities, the state agency’s lab has a capacity of 150 samples a week.

Should psyllids make an appearance in the San Joaquin Valley, a second lab is funded and would be operational within weeks, Batkin said.

A reason for the program’s success in San Diego County has been a massive public outreach campaign that urges homeowners to inspect potential host plants and trees in their yards. As the psyllids moved north, the public’s help became imperative.

“A University of California survey found there are more citrus trees in the backyards of homes in Orange and Los Angeles counties than in all of the state’s 300,000 acres of commercial groves,” Batkin said.

To put the survey results in perspective, every acre of commercial citrus has a minimum of 100 trees, he said.

As the industry/state/federal task force continues to deal with the psyllids, the goal is to keep the pest under control until a technique is found to combat the disease.

One approach, Batkin said, is to inject trees with a genetically modified protein that would prevent the disease from gaining a foothold, something akin to a vaccination.

Finding a cure — or a preventative — could dictate whether the domestic citrus industry survives.

Besides Florida, the disease has been detected in Georgia, South Carolina and Louisiana. Psyllids, but not the disease, have been found in Texas and Arizona.

The pest is in all of Mexico’s 23 citrus-growing states, and the disease has been detected on both coasts.

To date, none of the psyllids found in California traps has tested positive as a carrier of huanglongbing, now known in California agriculture simply as HLB. The task force plans to keep it that way.