The Animal and Plant Health Inspection Service (APHIS), in cooperation with the California Department of Food and Agriculture (CDFA), is expanding the citrus greening (Huanglongbing; HLB) quarantined area in California. APHIS is adding one square mile to the Santa Paula quarantined area in Ventura County, which impacts 151.7 acres of commercial citrus. APHIS is adding 10 square miles to the quarantined area in Riverside and San Diego Counties, which impacts 121.5 acres of commercial citrus. This measure parallels the intrastate quarantine that CDFA established on July 15, 2026. APHIS is taking this action because plant tissue samples from residential properties tested positive for Candidatus Liberibacter asiaticus, the causal agent of HLB.
APHIS is applying safeguarding measures outlined in 7 Code of Federal Regulations (CFR) 301.76 through 301.76-11 and associated Federal Orders that govern interstate movement of regulated articles from the quarantined areas. This action helps prevent HLB from spreading to areas that are not currently infested.
Effective immediately, the Animal and Plant Health Inspection Service (APHIS), in cooperation with the California Department of Food and Agriculture (CDFA), is expanding the area quarantined for citrus greening (Huanglongbing), caused by the Asian citrus psyllid, in California. APHIS is establishing a new quarantined area in the Ramona area of San Diego County of 93 square miles and is expanding the quarantined area in the Loma Linda area of San Bernardino and Riverside Counties by 26 square miles. These measures parallel the intrastate quarantines that CDFA established on March 2, and March 6, 2026, respectively. APHIS is taking this action because of citrus greening detections in plant tissue samples collected from residential properties. There are 25.16 acres of commercial citrus impacted by the new Ramona quarantine and 411.47 acres of commercial citrus impacted by the Loma Linda area expansion.
APHIS is applying safeguarding measures outlined in 7 CFR 301.76 and Federal Orders pertaining to the interstate movement of regulated articles from the quarantined areas in California. This action is necessary to prevent the spread of citrus greening to non-infested areas of the United States.
The APHIS Citrus Greening webpage contains specific changes to the quarantined areas in California. APHIS will publish a notice of this change in the Federal Register.
A much-anticipated research project on the deadly citrus disease huanglongbing, commonly referred to as “citrus greening” is coming to fruition, marked by the start of another harvest of a key citrus grove in Fort Pierce.
Harvest on the Millennium Block project, a seven-year University of Florida research project is underway, and researchers will use the data collected from fruit harvested from 2022 to 2026 to analyze how much these potential solutions offer farmers hope against citrus greening, with results expected later this year.
The damaging crop disease has decimated Florida orange and grapefruit groves, reducing production across all citrus-growing regions, reaching over 80% of the state’s citrus, and the Millennium Block was envisioned as a place where bold risks could be taken in the fight against citrus greening. The Millennium Block, which was planted at the UF Institute of Food and Agricultural Science’s (UF/IFAS) Indian River Research and Education Center (IRREC), in 2019, is now a 5,000-tree research project with trees that were bred to be tolerant to citrus greening, said Flavia Zambon, assistant professor of citrus production at UF/IFAS IRREC.
Citrus greening remains one of the most destructive challenges facing Florida’s citrus industry. Spread by a tiny bug called a psyllid, the bacterium that causes the disease attacks trees from the inside out, reducing fruit quality, yield and ultimately killing entire groves. Infected trees produce smaller, misshapen and bitter, green fruit – if they produce any at all. The disease spreads quickly through the flying insects, making containment difficult once a grove is infected.
“Citrus greening is a fundamental threat to the Florida citrus industry, and we’re eager to see the results of this long-awaited research trial to see what options we can suggest for farmers for greening-tolerant citrus varieties,” Zambon said.
The Millennium Block includes various citrus varieties in four research trials, one including 18 grapefruits and three commercial rootstocks, and the other three with 32 rootstocks grafted with Ray Ruby grapefruit, Glenn Navel sweet orange and UF-950 mandarin.
Harvest will continue through early February, and citrus will be pulled and juiced to be tested for physical marketable qualities, such as size, and juice quality attributes, such as sugar concentration and acidity, which affect the price that growers can expect to receive for their fruit.
“There are all these attributes that need to be in balance for both growers and consumers,” Zambon said.
In addition, they will evaluate the amount of market-quality citrus grown, both by the amount of fruit and by the total weight.
Researchers also used drones to evaluate the health of the Millennium Block’s trees and to see if there is a correlation between canopy size and the amount of fruit it produced – another potential predictive tool for farmers.
Harvest of the citrus fields at the Millennium Block at UF/IFAS has begun, and the fruit and juice from the harvest will be evaluated for their marketable qualities. Photo Credit: UF/IFAS, Joe McQueen.
ABOUT UF/IFAS The mission of the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) is to develop knowledge relevant to agricultural, human and natural resources and to make that knowledge available to sustain and enhance the quality of human life. With more than a dozen research facilities, 67 county Extension offices, and award-winning students and faculty in the UF College of Agricultural and Life Sciences, UF/IFAS brings science-based solutions to the state’s agricultural and natural resources industries, and all Florida residents.
Harvest of the citrus fields at the Millennium Block at UF/IFAS has begun, and the fruit and juice from the harvest will be evaluated for their marketable qualities. Photo Credit: UF/IFAS, Joe McQueen.
Ants are known to interfere with biological control of key citrus pests because they feast upon the sugary honeydew produced by small insects. One of these key pests is the invasive asian citrus psyllid that vectors the deadly huanglongbing citrus disease. As California growers diligently work to keep this disease out of citrus orchards, effective ant management is a critical component in the game plan. Ivan Milosavljevic from the California Citrus Research Board met with Matthew Malcolm on California Ag Network to discuss some new game-changing control strategies. Watch this brief interview and read more about it in California Fruit & Vegetable Magazine.
Huanglongbing (HLB), the deadly citrus disease that decimated the Florida citrus industry has shown up in Southern California and is now threatening the nation’s number one citrus state. HLB is primarily spread by the invasive Asian Citrus Psyllid, so managing this insect is key to preventing the spread of the disease. Pest mitigation practices may be costly, the California Citrus Research Board (CRB) introduced the California Citrus Research and Field Trials program (CA-CRaFT) to help fund commercial growers (both conventional and organic) to implement these practices. CRB representative Ivan Milosavljevic met with Matthew Malcolm on California Ag Network to share details. Watch this brief interview and read more in California Fruit & Vegetable Magazine.
Since the mid-2000s, citrus greening disease or Huanglongbing (HLB), has taken a toll on citrus fruits, causing significant crop and economic losses for citrus growers from Florida to Texas, and threatening to make its way to California — the nation’s #1 citrus state.
An aerial view of the new APHIS-funded Grove-First test site. Here researchers can partner with ARS scientists to evaluate therapies to combat citrus greening disease. (Photo by Cody Estes, owner of Estes Citrus Inc., Vero Beach, FL).
Photo Caption: An aerial view of the new APHIS-funded Grove-First test site. Here researchers can partner with ARS scientists to evaluate therapies to combat citrus greening disease. (Photo by Cody Estes, owner of Estes Citrus Inc., Vero Beach, FL).
With citrus trees in all major U.S. citrus-producing states affected by the bacterial pathogen, the Agricultural Research Service (ARS) is working to combat the disease. Citrus greening affects a variety of citrus fruits — with the greatest damage occurring within Florida’s orange groves.
Through the project “Grove-First,” ARS scientists Michelle Heck and Randall Niedz are working to stop citrus greening from overtaking these vital crops. Grove-First invites fellow researchers, citrus growers, and industry experts to test their scientific models to curb the effects of citrus greening directly in the field.
“We want to provide access to anyone in the research community to test their therapy against citrus greening,” said Heck. “This new project is going to open the door [to further research] and obliterate the barrier between the lab and the field. We are going to provide researchers with the ability to test their therapies directly in the field.”
With the support of ARS and USDA’s Animal and Plant Health Inspection Service (APHIS), Grove-First will leverage a commercial grove in Vero Beach, FL, to evaluate different treatments on both mature and young trees.
“The only way to determine if a treatment works is to actually see it work in the field,” added Niedz. “When you have a woody perennial like citrus trees, they are large, and therefore expensive to grow. Most researchers simply don’t have the resources, or access to the trees. With Grove-First, we now have a field site to welcome collaborations with some of the best researchers in the country.”
Heck tributes citrus growers for bringing Grove-First to fruition as a collaborative project. She said that in the past, the only way growers could fight citrus greening disease was to deliver therapies to trees using broadcast sprayers or through irrigation lines.
Because citrus greening disease attacks the vascular tissue of citrus trees, many growers have now turned to injecting individual citrus trees with an antibiotic treatment, such as oxytetracycline, which delivers more immediate treatment.
“The innovation to open up field testing and Grove-First research came from grower willingness to treat each individual citrus tree by direct injection,” said Heck. “This was transformative.”
Grove-First will welcome researchers with three important considerations.
“We want the treatments to be safe … safe for the (citrus) trees and safe for the workers,” Heck said. “They also must be affordable for the grower, and they must be available. The treatments that are safe, affordable, and available will be prioritized for screening through Grove-First.” – By Tami Terella-Faram, USDA-ARS Office of Communications
Stakes at All-Time High for Backyard & Commercial Trees in 2019
Detections of Huanglongbing (HLB), an incurable plant disease that kills citrus trees, increased by 160 percent in 2018 compared to the previous year, signaling the growing threat to the state’s iconic citrus trees, landscape and economy.
HLB is spread by a small pest called the Asian citrus psyllid as it feeds on citrus tree leaves. The disease is not dangerous to humans or pets, but it is fatal for citrus trees and has no cure. Once a tree is confirmed with the disease, it must be removed from the property in order to protect neighboring citrus trees.
The disease was first discovered in California in 2012 in Hacienda Heights. HLB was detected in 269 trees in 2017 and 699 trees in 2018, with a majority of these occurring in Los Angeles and Orange counties. The disease has not yet been detected in a California commercial grove.
HLB has devastated commercial citrus production in Florida. Over the course of 10 years, Florida’s commercial citrus industry lost $7.8 billion in revenue, 162,200 citrus acres and more than 7,500 jobs due to HLB. Should the disease spread from backyard trees in Southern California to nearby commercial citrus groves, the livelihood of California’s citrus production could impact about 3,900 farmers and 292,000 acres of citrus production in the state. Commercially grown citrus contributes $7 billion in economic impact to the state and employs more than 22,000 individuals.
“The livelihood of California’s commercial citrus industry and the generations of families it supports is at risk because of HLB,” said Jim Gorden, a citrus grower in the San Joaquin Valley and chair of the Citrus Pest & Disease Prevention Committee. “We are at a crossroads, and we must all work together to do what is necessary to protect our citrus.”
Asian Citrus Psyllid Adults
The California Department of Food and Agriculture (CDFA) has established quarantines throughout the state that limit the transport of citrus across state and international lines, and between areas where the psyllid and disease have been found. Additionally, CDFA has agriculture crews canvasing the state to inspect backyard citrus trees for the Asian citrus psyllid and HLB.
“The Department is committed to our partnership with California’s commercial citrus industry and residential citrus growers to fight HLB,” said Victoria Hornbaker, interim director of the citrus program at CDFA. “With more than half of California residences estimated to have a citrus tree on their property, and California citrus production supporting billions of dollars in our state’s economy, we all play an instrumental role in protecting our citrus.”
California residents play an important role in protecting the state’s citrus trees. Residents should:
Proactively inspect their citrus trees for the Asian citrus psyllid and HLB monthly, and whenever watering, spraying, pruning or tending trees.
Adult Asian citrus psyllids are brown, about one-eighth of an inch long, and feed with their body at a 45-degree angle on citrus leaves.
Symptoms of HLB include blotchy and yellowing leaves, premature and excessive fruit drop, lopsided fruit, and bitter, inedible fruit.
Call the state’s pest hotline at 800-491-1899 if the pest or disease is spotted.
Cooperate with agriculture officials who may ask to inspect or treat their citrus tree.
As part of tree maintenance, visit a local nursery or garden center to get advice on products that can help protect citrus trees.
When pruning citrus trees, be sure to dry out citrus clippings or double bag them before removing the plant material from the property.
Refrain from moving citrus plants, foliage or fruit as doing this may unknowingly spread the pest.
More information and photos of Asian citrus psyllids and HLB symptoms are available at CaliforniaCitrusThreat.org.
