Huanglongbing Research & Extension Output Network

Connecting Knowledge,
Funding, and Action
Against Citrus Greening

Discover the latest research on citrus greening, Huanglongbing (HLB). Stay informed about HLB symptoms, transmission, and the strategies being adopted to protect citrus crops worldwide.

About this platform

What is HLB-REON?

The HLB Research & Extension Output Network (REON) is a web-based platform created to provide reliable, up-to-date information on USDA-funded research projects conducted on HLB. Whether you're looking to learn about the organisms involved, explore management practices, treatments, or therapies, our search tools help you find the information you need.

Disease impact & research

About Huanglongbing (HLB)

Also known as "citrus greening," HLB is a bacterial disease that has severely impacted the global citrus industry. First detected in Florida in 2005, it has since spread to Texas and California. In Florida alone, orange production fell from approximately 240 million boxes in the early 2000s to just 18 million boxes in the 2022–2023 season, a decline of over 90%.

~240M
Boxes of Florida oranges produced before HLB
18M
Boxes produced in the 2022–23 season
>90%
Decline in Florida orange production

The bacterium Candidatus Liberibacter asiaticus causes HLB and is transmitted by the Asian citrus psyllid (Diaphorina citri). Infected trees produce bitter, misshapen fruit and, over time, become unproductive and eventually die. There is currently no cure for HLB.

Research efforts have been undertaken to unravel the mechanisms of this disease. Strategies in use include rigorous monitoring, insecticides to control psyllid populations, antibiotic and hormonal therapies, improvements in tree nutrition, and various cultural management practices.

Three interconnected research priorities

01
Pathogen, vector & host ecology
Researchers investigate how the bacterium operates, how it is transmitted by the psyllid vector, and how it interacts with host plants. This includes studying the pathogen’s life cycle, vector behavior and distribution, and the susceptibility and response of different citrus varieties to infection.
Ecology
02
Tree response to infection
Efforts focus on documenting physiological and biochemical changes in infected trees, understanding disease progression within the plant, and identifying early indicators of infection. This knowledge is critical for developing diagnostic tools and determining the best times and methods for intervention.
Diagnostics
03
Management & control strategies
Researchers explore resistance breeding, pest management to control the vector, treatments and therapies to mitigate disease effects, and integrated management approaches tested under real-world conditions.
Management

Explore data & research

Search the HLB portfolio

Browse, filter, and analyze USDA-funded HLB grants, data, and updates

🏆
Explore HLB grants
Quickly locate current and past USDA-funded HLB grants. Browse the full portfolio of research projects and use filters to retrieve the topics most relevant to your work, whether you are looking for information to improve your operations disease management, benchmarking your research area, or tracking investment trends across fields.
TopicLocationFunding amountUSDA agency
Browse all grants →
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Learn about our data
Our database provides structured information on HLB grant awards, principal investigators, funding agencies, research objectives, project timelines, and outputs. It also incorporates insights on key HLB topics, trends, and research patterns across projects. Documentation and guidance help users analyze, compare, and report data: for grant proposals, research planning, or trend analysis.
Grant awardsInvestigatorsOutputs
View data documentation →
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Stay informed
Explore newly posted updates, announcements, and resources from the HLB-REON project. This section offers a continuously updated stream of information so you can check in anytime and stay current with activities, publications, and opportunities across the network.
See recent updates →

Tools & collaboration

Access tools & resources

Decision support and media, coming soon

This section will feature practical tools to support HLB management decisions, including media resources and decision-support materials developed by the HLB-REON team and its collaborators.

Interested in collaborating with HLB-REON?

We welcome partnerships with growers, researchers, and organizations working on HLB management. If you're interested in proposing an activity or future collaboration — including with international partners — we'd like to hear from you.