Effective immediately, the U.S. Department of Agriculture Animal and Plant Health Inspection Service (APHIS) announced it was expanding the HLB quarantined area in California. The action was made on Sept. 1 in cooperation with the California Department of Food and Agriculture (CDFA). APHIS is adding 1 square mile to the Santa Paula quarantined area in Ventura County, which impacts 151.7 …
Considerations When HLB-Resistant Trees Arrive
The development of citrus varieties that can resist HLB could eventually change how growers manage the disease. However, a recent study suggests the transition may not be as simple as planting resistant trees and stopping control of the Asian citrus psyllid (ACP) that spreads HLB. A paper about the research, published in the April 2026 issue of Agricultural Systems, examines …
HLB Confirmed in Imperial County for First Time
California Department of Food and Agriculture (CDFA) and U.S. Department of Agriculture (USDA) officials have confirmed the detection of HLB in one tree in a residential property in the city of Calexico, Imperial County, California. This is the first HLB detection in a tree in Imperial County. In November 2025, an Asian citrus psyllid (ACP) was confirmed positive in Imperial …
PDIs Promising for Sustainable HLB Management
A recent University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) article addressed the use of plant defense inducers (PDIs) as sustainable alternatives to oxytetracycline (OTC) injection for HLB management. Researchers Lauren Fessler Mathews, Ana Redondo and Ozgur Batuman at the Southwest Florida Research and Education Center (SWFREC) authored the article. Slightly edited excerpts of the article follow: PDIs …
USDA Report Highlights HLB Efforts
The U.S. Department of Agriculture Animal and Plant Health Inspection Service (USDA APHIS) highlighted huanglongbing (HLB) disease in the citrus section of its recent Plant Protection and Quarantine (PPQ) 2025 Annual Report. It recognized HLB as the most serious disease of citrus, currently impacting Florida and Texas and threatening citrus in Alabama, Arizona, California, Georgia, Louisiana and Mississippi. The report …
Canopy Management Critical for HLB-Affected Citrus
By Tripti Vashisth, Meryam Manzoor and Johann Hiller Fruit quality and yield remain major concerns for sweet orange growers in the HLB era. Both are closely linked to the tree’s ability to support developing fruit throughout the season. Leaves are the primary source of carbohydrates needed for fruit growth, retention and juice development. Canopy density and leaf area directly influence …
HLB-Tolerant Mandarin Hybrids Show Promise
As citrus growers continue searching for varieties that can perform under huanglongbing (HLB) pressure, researchers are looking beyond tree survival. Fruit quality, flavor and consumer acceptance are becoming increasingly important parts of the equation. A new study evaluated several HLB-tolerant mandarin hybrids and identified selections that combine disease tolerance with traits that could make them attractive for fresh-market production. An …
Pathologist Provides Update on HLB Spread in Georgia
Citrus greening disease continues to loom over the cold-hardy citrus region. While the industry expands in South Georgia and North Florida, the threat of the disease (also known as huanglongbing, or HLB) remains a focal point of citrus meetings, including on July 28 at the Southeast Georgia Citrus Update in Lyons. Jonathan Oliver, University of Georgia (UGA) assistant professor and …
Research Shows How HLB Progresses Through Trees
Recent research provides one of the clearest pictures to date of how huanglongbing (HLB) disease develops over time and affects different parts of a tree. An article about the research — “Microscopic Atlas of Citrus Huanglongbing Unravels Its Sequential Disease Development Mechanism” — was published in the journal Phytopathology. The authors are researchers Diann Achor, Camila Ribeiro, Jinyun Li and …
Citrus Species Show Different Responses to HLB
Researchers are studying why some citrus species appear to handle huanglongbing (HLB) better than others. Understanding these differences could help breeders develop more resilient citrus varieties and rootstocks for future production. A new study compared nine citrus species infected with HLB and identified differences in how the plants respond to the disease, including changes in nutrient levels, stress responses and …
New Research Tool Could Speed Search for HLB Treatments
A new research platform may help scientists identify potential treatments for citrus greening disease faster, potentially speeding up the search for solutions. Citrus greening, also known as huanglongbing (HLB), is caused by the bacterium Candidatus Liberibacter asiaticus (CLas). The disease disrupts the tree’s ability to transport nutrients, leading to symptoms such as blotchy leaves, small and misshapen fruit, poor juice …
Tools to Address Drought and HLB in Texas
Huanglongbing (HLB) has already taken a heavy toll on U.S. citrus production, but growers in Texas’ Lower Rio Grande Valley face an additional and compounding challenge — a persistent drought. Current irrigation practices relying on the Rio Grande River as the sole source of water are no longer sufficient to meet the year-round water needs of citrus trees. That is …
Two-Step HLB Defense for Young Trees
A newly published study suggests that the use of individual protective covers (IPCs) followed by monthly applications of homobrassinolide (HBr) after IPCs are removed is beneficial. The two-step approach can help young mandarin trees stay healthier longer and produce more fruit in Florida’s HLB-endemic environment. The study, “Combining Individual Protective Covers and Homobrassinolide Treatment Prolongs Tree Health and Increases Fruit …
Early Data on Biofertilizer for HLB-Affected Trees
By Flavia Tabay Zambon and Paulo Eduardo Branco Paiva Florida’s citrus industry has faced severe decline due to huanglongbing (HLB, also known as citrus greening). Production has dropped 92% since the 2003–04 season, according to the U.S. Department of Agriculture Economic Research Service. Growers have relied on cultural practices, tolerant varieties and antimicrobial treatments, especially oxytetracycline (OTC), which has recently …
Scientists Speak About Long-Term HLB Solutions
The recent Florida Citrus Industry Annual Conference featured seminars from several scientists who are working on solutions to fight huanglongbing (HLB) disease. GENETIC RESEARCH Vivian Irish of Yale University presented her research on combating HLB through gene editing. She noted several promising gene-editing targets have been identified. Plans call for getting these lines planted to evaluate their resistance to HLB. …
Compost, Rootstocks and HLB
Compost-amended plots (left) had more weeds than those with no compost. A new study published in Scientific Reports examines whether repeated compost applications could improve the health and productivity of young citrus trees growing under endemic huanglongbing (HLB) conditions in Florida. Gabriel Pugina, Caroline Tardivo, Brittney Monus, Emma Dawson, Sarah Strauss and Ute Albrecht of the University of Florida Institute …
How HLB Research Has Evolved
Huanglongbing (HLB, or citrus greening) disease has been the focus of an enormous amount of scientific research over the past two decades. A new study — “Bibliometric Mapping of Citrus Greening Disease Reflecting Trends, Shifts and Focus Areas” — takes a unique look at that research. It analyzes thousands of scientific publications to identify where scientists have concentrated their efforts …
HLB Drives Brazilian Citrus Expansion to New Regions
Brazil’s Fundecitrus on May 28 participated in the Expocitros 2026 lecture session “Focus, Efficiency and Control.” The session focused on the primary phytosanitary challenges facing the Brazilian citrus industry. A session highlight was a lecture by agronomist Ivaldo Sala, coordinator of Fundecitrus’ Technology Transfer Department. Sala’s lecture title was “HLB: How to Proceed in New Citrus-Growing Regions.” Sala said the …
Soil Amendments Improve Water Use in HLB-Affected Citrus
By Tripti Vashisth and Taylor Livingston Florida is currently experiencing one of the most severe droughts in the past 25 years, putting HLB-affected trees under intense water stress. With Florida’s well-draining sandy soils and increased water demand in HLB-affected trees, growers are in a difficult position trying to maintain adequate tree hydration. Soil amendments, such as biochar and compost, can …
Recent Research Offers HLB Resistance Insights
Research conducted in China may hold significant implications for the sustainable development of citriculture amid the ongoing global HLB epidemic. The work offers novel insights into vascular immunity and plant defense responses. The article (Single-nucleus transcriptomics reveals the cellular immune responses to Candidatus Liberibacter asiaticus in rough lemon) appeared in the January 2026 issue of Horticulture Research. The authors are …




















