Citrus Research and Development Foundation, Inc.

Oranges, Tangerines, Lemons and Limes Provide Nutrition and Food Flavorings, and Are an Important Source of Vitamin C for Healthy Immune Systems, Something Needed Now More Than Ever During Our Current Global Health Crisis.globally, the Us Is One of the Top Three Countries for Consumption of Citrus Per Capita. Citrus Production in the United States Is Worth $3 Billion and in Florida and California Provides Nearly 100,000 Jobs. However, the Future of the Citrus Industry Producing Orange Juice and Fresh Fruit Is Threatened Worldwide by a Devastating Disease Known as Huanglongbing (HLB for Short). It Is Also Referred to as "citrus Greening."the Disease Originated in China and Has Spread Rapidly Across the Globe, Leading to the Loss of More Than One Million Citrus Trees. the Disease Is Difficult to Stop Because the Causal Bacterium Lives in the TREE'S Phloem, Which Is a Part of the PLANT'S Circulatory System Lying Just Beneath the Bark, That Is Very Difficult to Reach.the Disease Is Carried by a Flying Insect Called a Psyllid, Which Is Smaller Than a Sesame Seed. the Psyllid Becomes a Transmitter of the Disease by First Feeding on the Leaves of an Infected Tree, Ingesting HLB Bacterium. Once the Bacterium Is in the Psyllid, the Psyllid Conveys the Disease to Other Trees It Feeds Upon. in This Way, the Disease Is Transmitted From Tree to Tree.suppression of the Psyllid Was Tried in Florida But Failed. It Is Now Assumed That Virtually Every Tree of Fruit-bearing Age in Florida Is Infected.hlb Affects Citrus Trees From the Roots Up, Clogging the TREE'S Vascular System and Disrupting Carbohydrate Production in the Leaves and Nutrient and Water Flow Throughout the Tree. What Results Is Debilitation of the Tree With Fewer Leaves and Small, Misshapen Fruit That Develops a Bitter Taste. Infected Trees Decline in Production a Few Years After Infection.over the Past Ten Years, Hundreds of Millions of Dollars Have Been Spent on Research in the United States on This Problem. While We Now Know More About the Disease Than Ever, and While Enhanced Nutritional Programs and Other Horticultural Practices Have Improved Yield and Fruit Quality, Not a Single Cost-effective Therapy Has Resulted From These Efforts. Why Is This? There Are Several Reasons, But One of the Major Ones Is That This Bacterium Can Only Propagate in the Citrus TREE'S Circulatory System or PSYLLID'S Gut, Making Traditional Screening and Discovery in the Laboratory Difficult. Detecting the Disease in Citrus Trees Is Also Tricky Because Signs of the Disease Are Not Manifested Quickly; It Can Take Years for an Infected Tree to Show Visual Symptoms. and Since Nearly All Mature Trees in Florida and Many in Texas Are Infected, There Is a Huge Reservoir of Inoculum Being Spread by the Insect Carriers. in California, More Than 1,500 Trees in Residential Settings Have Been Found to Be Infected, Causing Them to Be Removed to Keep the Disease Out of Commercially Producing Groves.to Addressa Problem of This Complexity and Magnitude, a Concerted Effort Is Needed Which Combines the Expertise Across Several Academic Disciplines, the Agrochemical Industry and Citrus Industry Experts. New Approaches Are Needed to Identify Potential Products, Quickly Detect the Disease, and Test Trees for the Ability to Suppress or Kill HLB. Two Approaches Are Being Investigated in Parallel to Speed Development.in One Case, the Agrochemical Industry Partner Is Looking for Naturally Occurring Microbes That Could Fight the Disease. Microbes Protect Both Humans and Plants Against Many Diseases and Are Important for Our Health. in Fact, Many of Our Important Human Therapies, Like Erythromycin and Penicillin, Are Produced by Microorganisms. a Library of More Than 100,000 Isolated Microbial Strains Is Being Searched for One That Could Naturally Control Citrus Greening.in a Second Approach, More Than 200,000 Synthetic Compounds Are Being Screened to Determine If They Can Boost the PLANT'S Defense System. Think of It as Developing a Vaccine for Plants. Combining Different Ways to Stop Citrus Greening Can Help Keep HLB From Developing Immunity to the Therapies.after Laboratory Testing on Model Organisms, It Is Important to Begin Testing on Plant Systems. at Texas A&m, a Researcher Has Developed a Way to Use Root Tissue From Infected Plants Raised in the Greenhouse to Provide a Rapid Method for Screening Microbes and Chemicals for Their Potential in Killing HLB. the Ones Found to Be Active Are Then Sent to a Researcher at the University of Florida Where a Greenhouse Citrus Assay Has Been Developed for Testing Therapies for Control of HLB. While This Test Takes Several Months, It Provides Valuable Information on How Therapies Can Be Applied to Citrus to Reach the Pathogen and How Often Treatment Is Needed. Finally, the Best Performing Microbes and Compounds Are Tested in Field Trials in Florida. Since the Disease Is Everywhere There, It Is Certain That the Trees Will Eventually Become Infected, Making It Possible to Determine If the Microbes and Compounds Are Effective. to Track the Activity of the Therapies, Testing Is Carried Out on Citrus Transplants Coming From Nurseries Without Disease. as They Are Exposed to the Population of Psyllids Carrying the Bacterium, the Progress of Disease Development Can Be Monitored to See How the Therapies Are Performing.traditional Methods for Following Disease Are Challenging Because the Bacterium Is Not Evenly Spread Throughout the Tree Itself, and Bacterial Distribution Varies With the Time of the Year. for Example, in Certain Seasons, the Bacterium May Move Into the Roots So Sampling Leaves for the Disease Will Give a Negative Result Even If the Tree Is Infected. to Address This, a Researcher From the University of California Davis Has Developed a Way to Look at the TREE'S Response to the Infection, Like Monitoring the Level of White Blood Cells in an Infected Human. Here, Infected Citrus Trees Produce an Immune Response That Can Be Seen in Any Tissue of the Tree, So Sampling Is Not a Problem. Also, This Response Occurs Very Quickly After Infection Even While the Trees Do Not Show Any Disease Symptoms. This Method Is Being Compared to the More Traditional Disease Detection Method to See If Bacterial Infection Is Detected Sooner and More Accurately.in the End, It Is Hoped That by Combining the Screening Capabilities and Product Development Experience of the Agrochemical Industry Partner With the Expertise Found in Top Agricultural Research Universities in the United States, While at the Same Time Maintaining Good Communication With the Citrus Industry, We Will Make Progress in Identifying Treatments That Will Slow Down or Halt This Disease. the Result Will Be Healthier Trees With More Production to Sustain Us Citrus Production, While at the Same Time Protecting the Jobs Associated With a Vibrant Citrus Industry.we Are Determined to Succeed Because It Is Hard to Imagine a World Without Citrus.