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Multi-Agency Response to Devastating Citrus Disease

Huanglongbing (HLB), also known as citrus greening disease, is one of the most serious citrus diseases in the world. It poses a very real and growing threat to citrus production in the United States. In response to industry concerns, USDA established a unified emergency response framework to better position the Department to respond in a more agile, concerted, and direct way to both the immediate and long-term needs of the citrus industry.

HLB Multi-Agency Coordination (MAC) System

Participating organizations include USDA's Animal and Plant Health Inspection Service (APHIS), Agricultural Research Service (ARS), and National Institute of Food and Agriculture (NIFA), the U.S. Environmental Protection Agency, as well as State departments of agriculture and industry groups. These partners have formed an HLB Multi-Agency Coordination (MAC) Group—or HLB MAC Group—to jointly establish research priorities, coordinate activities, and collect, analyze, and disseminate information. The HLB MAC Group helps to coordinate and prioritize Federal research with industry's efforts to complement and fill research gaps, reduce unnecessary duplication, speed progress, and more quickly provide practical tools for citrus growers to use.

The HLB MAC provides industry with a single Federal point of contact for all Federal and State entities that work on citrus issues. In addition, the framework maintains and shares a common operating picture of HLB response that is accessible across jurisdictions and functional agencies. This common operating picture greatly improves strategy development, policymaking, and resource allocation—ensuring funds are invested where they can have maximum impact based on input of all participants.

Specifically, the HLB MAC:

  • Coordinates funding across Federal and State agencies, universities, and private companies to maximize investments, reduce duplication, and focus research on the most promising ideas.
  • Rapidly funds projects most likely to deliver effective and practical tools to growers.
  • Combines successful project results into holistic and sustainable solutions.
  • Helps move field-tested tools into commercialization.
  • Maintains sense of urgency in the research community, driving them to find near-term solutions.

HLB MAC-Funded Projects

Since 2013, the HLB MAC has invested nearly $47 million to speed the development of tools that could help the U.S. citrus industry fight back against HLB. Projects have focused on four critical areas: Asian citrus psyllid (ACP) control, infected tree therapies, technologies to protect new plantings against HLB infection, and early detection technologies.

HLB MAC-funded projects have:

  • Tripled the production and release ACP-killing wasps, from 4 million to 12 million per year. These wasps have reduced ACP populations by more than 50 percent in Texas and as much as 99 percent around California release sites.
  • Removed nearly 6,000 acres of abandoned groves in Florida, eliminating uncontrolled ACP habitat and prompting state legislation to incentivize further removal of abandoned groves.
  • Trained and field tested canines to detect HLB in commercial and residential settings.
  • Applied thermotherapy to more than 3 million HLB-infected trees in Florida to extend trees’ productive life by promoting new growth and slowing the progress of the disease.
  • Helped move thermotherapy technology to market by delivering a prototype machine to growers who used the design to build their own machines and private companies who improved the technology and now offer thermotherapy services.
  • Developed soil acidification technology that could be used on a broad scale to lower the pH of infected tree roots, helping to improve overall tree health and production.
  • Saved growers from investing in ineffective technologies by researching and disproving claims that adding microbials to grove soil would improve tree growth.
  • Field tested two antimicrobial treatments to improve the overall health and quality of infected trees. That data was used by Florida to obtain a Section 18 exemption from the Environmental Protection Agency, allowing them to use antimicrobials on an emergency basis.
  • Initiated a rapid propagation project to accelerate field testing of 35 varieties of HLB-tolerant mandarin and sweet orange trees, which will make them available 2 years earlier than traditional propagation practices.

View the FY2019 list of funded projects (PDF, 214 KB).

View the FY2019 project summaries (PDF, 1.3 MB).

Current Activities

To determine the best management practices and methodologies for producing citrus under the threat and pressure of HLB, the MAC will work with interested growers to conduct large-scale field tests of the most promising tools and technologies that have been developed in recent years. Through these tests, we will:

  1. Compare lab results to real-world environments
  2. Determine the scalability of new methods
  3. Obtain direct input from growers on the new methods

The MAC is working closely with stakeholders and cooperators to develop and implement HLB-mitigation testing in 2020.  As a result, the HLB MAC will not be accepting submissions for research proposals this year.

Contact the HLB MAC Group

Contact a member of the Multi-Agency Coordination (MAC) Group for more information.

Sign Up for HLB MAC Updates

If you would like to receive timely updates on the HLB MAC Group's activities, we invite you to join the APHIS Stakeholder Registry. Once you sign up, you can subscribe to the "Citrus Pests and Disease" topic through the following steps:

  1. Select Plant Health Information.
  2. Select Plant Health in the US (Domestic).
  3. Select Pest Management.
  4. Check the Citrus Pests and Disease box.
  5. Submit your subscription.