Huanglongbing disease detected in Ventura County.
Natalie Willis, Reporter, Valley Ag Voice
In response to the California Citrus Disease and Prevention Program’s confirmed case of Huanglongbing disease from an Asian citrus psyllid cluster in Ventura County, citrus growers initiated vigorous delineation efforts throughout the state. According to David Haviland, farm advisor at UC ANR’s cooperative extension program in Kern County, the psyllid is well-established in Southern California and other coastal areas in the state, but the Central Valley has reported relatively low numbers.
“Thus far, what’s been found doesn’t trigger a quarantine,” Haviland said. “The hope is that nothing else is ever found. All the extra delineation efforts that are going on right now will determine whether or not this is some sort of anomaly or if it is the finding of an infestation that will need an immediate response.”
The positive sample in Ventura County — comprised of 12 adult psyllids from a residential citrus tree — is the first confirmed case of the HLB disease in Ventura County. While HLB has not been detected in Ventura County citrus trees, Ben Faber, UC Cooperative Extension subtropical crops advisor, explained that the find is devastating.
“It means that Asian citrus psyllid that is infected with the HLB bacteria is present in the middle of a citrus-growing area that is currently and historically important for lemon production,” Haber said. “The disease is a tree killer, and it’s happening to growers who are already having difficult times with low lemon prices, making it difficult for them to stay and continue farming.”
Haviland explained that the psyllid feeds on new growth from citrus trees and expels HLB bacteria back into the tree, which there is no cure for — a large part of Florida’s citrus industry was wiped out by the disease. Since HLB arrived in Florida, the state went from producing nearly 80% of the nation’s non-tangerine citrus fruit to less than 42%, according to the USDA.
The bacteria results in unmarketable fruit that is asymmetrical in shape and leaves a bitter flavor, according to UC’s Integrated Pest Management Program. An infected citrus tree will die within five to eight years.
Asian citrus psyllid arrived in Southern California from Mexico roughly 15 years ago. While it has been well-established in Southern California, central and northern areas only periodically detected the pest. However, the psyllid and disease spread quickly, Haviland explained. In Florida, the arrival of Asian citrus psyllid spread to commercial citrus orchards, requiring growers to apply broad-spectrum pesticides up to fifteen times per year.
“This is a disease that’s wiped out a large percentage of Florida’s citrus industry, and it’s a disease that California does not want — definitively does not want,” Haviland said. “So, the threat is enormous.”
MANAGEMENT
Monitoring programs throughout California are routine in their efforts to collect psyllids for area-wide surveys and management, and the positive case in Ventura County was found in a group testing of psyllids without a defined link to a citrus tree. Haviland explained that the state has been monitoring psyllids throughout the past decade to control the pests where they are found, remove infested trees, and initiate quarantines in certain areas.
California’s mitigation efforts are regionally different as more established areas in the southern part of the state receive area-wide pesticide applications, whereas northern and central areas use an eradicative approach. In this approach, infested orchards and neighboring orchards are treated quickly with insecticides, according to UC IMP.
Along with statewide efforts, Haviland noted that citrus growers are well-organized and coordinated, establishing treatments to implement collectively.
“It’s not just one grower trying to decide what they want to do. The growers actually all act as a unit, as a grouping, where all of them together, at the same time, make a treatment,” Haviland said. “That way, you make sure a pest isn’t just bouncing from one grower to another.”
UC IMP’s website offers various management options for California citrus growers.
LOCAL IMPACT
The presence of Asian citrus psyllids and the subsequent HLB disease in the Central Valley has remained relatively low, but the threat is still present, according to the California Department of Food and Agriculture.
In January, the CDFA confirmed the pest’s presence in a Bakersfield collection. An emergency response was soon enacted to disrupt the psyllid’s life cycle to avoid future detections in Kern County. The CDFA report explained that the spread of the bacteria would significantly impact California’s citrus industry, which totals over $3.4 billion in sales, and its presence would increase citrus production costs.
“Ventura is a significant jump outside of that Southern California region. It’s also what you might call one step closer to the Central Valley, which is where the majority of California citrus is produced,” Haviland said. “A lot of dedication is going to go into this particular positive find to really delineate it to figure out exactly what’s going on… we don’t want it inching closer to the Valley.”
