Upwards of 9,000 acres of commercial citrus could be included in a new Asian citrus psyllid quarantine in Kern County after the pest was discovered in large numbers in and near Bakersfield.

The finds were made in September and October, primarily in residential neighborhoods in city. Those discoveries spilled into at least one commercial grove in the Arvin area south of town, pushing growers to implement area-wide spray programs in an effort to knock back the invasive pest.

As the California Department of Food and Agriculture draws up an ACP quarantine boundary that will encompass about 14 percent of the countywide citrus acreage, growers are being informed about regulated protocols they’ll need to employ within the quarantine zone, and best management practices industry leaders want across the entire state.

Since Kern County produces a significant amount of the state’s fresh citrus, officials are warning growers to be vigilant in the monitoring and treatment of the dangerous pest that seems to have infiltrated urban neighborhoods in the city.

The ACP can spread a lethal disease in citrus called Huanglongbing. To date, 11 cases of the disease were discovered in residential neighborhoods in Los Angeles County, Kern County’s neighbor to the south. Kern County Agricultural Commissioner Ruben Arroyo is doing what he can to help growers ensure the disease doesn’t make it into his county.

According to University of California Research Entomologist Beth Grafton-Cardwell, commercial citrus growers are already into their second coordinated spray to control the psyllid, which she calls a good practice.

Experts concerned

University experts recommend commercial growers apply registered insecticides across a wide area within a few days of each other to avoid simply chasing the pest around through patch-work pesticide applications. Since growers are likely treating for several different pests at the same time, Grafton-Cardwell recommends they only use ACP-effective insecticides and avoid chemicals that do not kill the psyllid.

“If everyone treats over a large area at the same time it’s more effective than treating small areas here and there,” Grafton-Cardwell said.

The quick explosion of psyllid discoveries troubles the citrus expert.

“I’m very concerned about the number of psyllids in Bakersfield,” Grafton-Cardwell told a standing-room only audience in Bakersfield on Nov. 12.

John Hooper, an environmental program manager with the CDFA, said most homeowners have been helped to understand the seriousness of the psyllid outbreak and are allowing state officials to treat their trees with foliar and systemic insecticides. Commercial growers are fully responsible for their own treatments.

According to Hooper, 4,500 yellow, sticky traps used to survey for psyllids have been placed in Kern County – 3,500 of those are located in the city of Bakersfield. These traps are currently being serviced daily or as close to it as humanly possible. Visual surveys are ongoing in urban settings and commercial groves.

Arroyo said he recently added five people to his staff to help with trapping and monitoring for the psyllid.

Quarantine

Bob Teagarden grows Navel oranges, Satsuma mandarins, clementine’s and grapefruit for the Nickel family east of Bakersfield. He said while it appears his groves will be outside of the quarantine zone regulators are drawing up, his interest is in combatting the pest that spreads the deadly citrus disease.

“My concern is the actual spread of HLB,” Teagarden says. “Whether we’re in or out of a quarantine zone is not the issue. This is all about keeping HLB out of here.”

So far state tests of live psyllids captured during surveys have been negative for the Candidatus Liberibacter asiaticus bacterium known to cause HLB, Hooper says.

Quarantine regulations will set up the need for compliance agreements that growers and packers must sign in order to ship fruit. Specific provisions laid out in these agreements will dictate the practices growers and packers must employ when moving fruit in the region.

Those requirements will include removal of stem and leaf materials prior to transportation and other protocols such as specific timings of spray treatments and various other restrictions.

Given that not all areas will be within the quarantine, it will be important for growers to be aware of boundaries and transportation routes used to transport their fruit.

Arroyo says some have asked him to push for a countywide ACP quarantine, which would effectively make it easier to move fruit around the county. Because neighboring Tulare County has a countywide ACP quarantine, this would make it easier to ship fruit between the two counties.

For all those supporting such a move, others say this would open up the San Joaquin Valley to shipments of fruit from southern California without the kinds of safeguards currently in place to prevent further spread of the ACP. For that reason not everyone is in agreement with a countywide ACP quarantine in Kern.

Growers can visit the Kern County Department of Agriculture's website for the latest ACP information, including compliance agreements that must be signed.

Biological controls

Given the large numbers of psyllids discovered in Bakersfield and the fear that there are many more in the city, some at a Kern County meeting on Nov. 12 asked about the possibility of releasing the two species of parasitic wasps employed in southern California’s fight against the ACP.

Two parasitic wasps – Tamarixia radiata and Diaphorencyrtus aligarhensis – are being released in urban settings throughout southern California to help reduce ACP numbers.

Grafton-Cardwell personally believes releases should be should be made in the urban areas of Bakersfield as soon as possible to help control ACP populations. She does not recommend their release in commercial citrus due to chemical pesticide use that could kill the parasitic wasp.

One problem with releasing the two wasps is the number of them available for public release. With only one facility in California currently rearing the wasp for urban release in southern California, Grafton-Cardwell fears there aren’t enough of the creatures reared to combat further urban outbreaks of the ACP, which are beginning to pop up in cities throughout Central California.

As the California citrus industry faces further expansion of the ACP, two of the industry’s key organizations – California Citrus Mutual and the Citrus Research Board – will host an HLB early detection technology summit on Dec. 1 at the Visalia Convention Center, 303 E. Acequia Ave., Visalia.

The event will feature presentations from lead researchers working on early detection technologies for HLB.

The event runs from 8:30 a.m. to 2:30 p.m. Registration is required at www.citrusinsider.org, or by calling California Citrus Mutual at (559) 592-3790.

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