TULARE, Calif. — The confirmation May 22 that three Asian citrus psyllids were trapped in the San Joaquin Valley drove home the point that the citrus pest is expanding its presence in the state’s largest citrus-producing region.
If the psyllid behaves in the Central Valley as it did in Southern California, where it is well established, populations will continue to build until eradication is no longer practical, said Beth Cardwell-Grafton, a University of California-Riverside research entomologist and director of the Lindcove Research and Extension Center.
In preparation for that day, University of California entomologists and the Citrus Pest & Disease Prevention Program are developing an area-wide management program.
When the plan would be implemented is unknown and will depend on how long San Joaquin Valley growers can keep the psyllid at bay, she said.
“We’re not expecting this to roll out until the populations are so high we can’t eradicate them,” Grafton-Cardwell said.
Borrowing from Florida’s Citrus Health Management Areas, also known as CHMAs, Grafton-Cardwell said the goal is to have all of the growers in a large area spray for psyllids at the same time to maximize treatment efficacy. That way the pest can’t jump from a treated grove to an untreated grove to escape the chemicals.
In Florida, CHMAs have been successful in significantly reducing psyllid numbers.
Grafton-Cardwell outlined the program at a meeting designed for packinghouse personnel, May 22.
“The main goal is to slow the spread of psyllid and buy time for the scientists to find a cure,” she said.
Psyllids can carry hunglongbing, also known as HLB or citrus greening. The bacterial disease, which is harmless to humans, can weaken and even kill citrus trees. In Florida, where the disease is entrenched, it has caused more than $3.6 billion in lost revenue, she said.
Although only one tree has been confirmed with the disease in California, and that was in the Los Angeles basin, she said most experts believe there are other infected trees that just haven’t been identified.
Eradication is no longer possible in Southern California because of high psyllid numbers and large urban centers. In the San Joaquin Valley, the California Department of Food and Agriculture and the citrus industry continue to work toward localized eradication when a psyllid is trapped.
Under the plan, the San Joaquin Valley would be divided into nine psyllid management units. Each one would involve about 25-30 growers. A “captain” would lead each group and work with a Citrus Pest & Disease Prevention Program grower liaisons.
Based on input from University of California researchers and Exension specialists, growers within a management area would all treat within a few days of each other.
“So communication is going to be absolutely critical,” Grafton-Cardwell said. “This is going to be like the rollout of an army.”
In Florida, many growers treat monthly, but Grafton-Cardwell said she doesn’t expect California’s citrus producers to have to apply insect control nearly as often. She envisions three to four treatments yearly when the psyllid is most active or when it would be most susceptible to control measures.
The goal of the voluntary management practices is to halt movement of plant material in and out of groves, regardless of whether they’re in a quarantine zone.
“If you stop the movement of plant material, you stop the movement of psyllid,” Hill said.
Growers and packers need to enlist workers, farm labor contractors, haulers and equipment operators to ensure that machinery, bins, picking bags, ladders and everything else entering and leaving groves are free of plant material.
“Any piece of equipment that you have coming on and off your orchard, make sure it’s been properly cleaned and sanitized,” he said.
In other news, Tulare County Agriculture Commissioner Marilyn Kinoshita confirmed that two Asian citrus psyllids had been detected in two separate traps in different areas of Visalia. The finds should prompt treatments of all host material within 400 meters of each and expand the current quarantine, she said.
An additional psyllid was picked up in a glassywing sharpshooter trap at a citrus packinghouse near Delano, she said. The state is treating it as a lone hitchhiker and has increased the number of traps around the facility. No treatment will be conducted if no additional psyllids are trapped.
Packers who are inside quarantine areas and who want to ship mandarins with stems and leaves outside the quarantine or interstate can now do so, providing the fruit has undergone standard packinghouse treatments, said Nawal Sharma, CDFA quarantine response program supervisor.
They include washing with brushes, waxing and drying. The rule change was effective May 21.