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Key accomplishments in fighting citrus greening disease 2005 – 2020

Key accomplishments in fighting citrus greening disease 2005 – 2020:

Building on a solid foundation of IFAS Research

Huanglongbing (HLB), also known as citrus greening disease, has devasted Florida’s citrus industry for the last 15 years.  Since first detected in southern Florida in 2005, the disease is now present in virtually 100 percent of the state’s groves, impacting both the processed and fresh fruit sectors.  The disease is caused by a bacterium which is spread by an insectcalled the Asian citrus psyllid.

Since the discovery of HLB in Florida, the faculty and staff of the University of Florida’s Institute of Food and Agricultural Sciences (IFAS) have dedicated themselves to finding workable solutions for citrus growers to first sustain their operations and now return to profitability.  And despite the fact that there has never been a solution developed for this disease in it’s original country of origin, more scientific discoveries have been found in the past 15 years of dealing with HLB in Florida than in the 100 years preceding. None of these research milestones would have been achieved without the support for IFAS research provided by state, federal and grower organizations.

This is a summary of areas of key advancements thus far in the citrus greening fight accomplished by UF/IFAS scientists.

 Response to HLB discovery in Florida

  • Provided scientific support to FDACS, growers and Federal Agencies on approaches to minimizing disease spread
  • Established a plant diagnostic clinic to assist growers in identifying HLB in their groves
  • Established the Citrus Health Management Program that coordinated psyllid control efforts of growers over more than 450,000 acres of citrus to slow disease spread

Managing psyllids to slow the spread of HLB

  • Conducted field trials to develop a ‘tool box’ of recommended products for growers to use to control psyllids
  • Developed season-long psyllid management programs based on detailed scientific studies of psyllid feeding behavior and long-distance movement patterns
  • Studied the survival and movement of bacteria within the psyllid to identify novel approaches to psyllid management

Understanding how HLB affects citrus trees

  • Discovered disease affects the tree root system thereby preventing uptake of water and nutrients trees need to survive
  • Conducted studies detailing bacterial movement in the tree and how this relates to subsequent disease spread to new trees
  • How bacteria affect the tree genetically, causing a cascade of events leading to disease

Development of new disease tolerant citrus varieties

  • UF/IFAS has developed and released 18 citrus rootstocks and 20 new fresh and juice fruit varieties to Florida growers
  • Sugar Belle, a fresh fruit variety, was the first of UF’s new citrus varieties released and is the most HLB tolerant scion variety grown in Florida
  • Accomplished through conventional breeding and biotech approaches
  • Identified genes that play a role in HLB (both resistance and susceptibility)

Improved grove production practices to keep growers in business

  • Research over the past decade has led to new production practices growers are using now to remain in business
  • Developed new guidelines for fertilization, irrigation and soil health practices to keep trees alive while increasing fruit yield and quality
  • Evaluated use of antibiotics to provide guidance on how best to utilize
  • Developed the Citrus Under Protective Screen (CUPS) system being used now by many fresh and gift fruit growers to maintain those niche markets

 

Research-based solutions for the future of the Florida Citrus Industry

  • The next generation of new disease-resistant citrus varieties from the UF/IFAS citrus breeding program are being evaluated in the field now; this includes varieties developed using gene editing to remove genes responsible for disease symptoms
  • Development of new psyllid control approaches that reduce pesticide use in favor of more environmentally friendly sustainable solutions for pest management
  • Development of anti-bacterial products or plant-derived compounds that eliminate the HLB-causing bacteria in the plant or reverse the plant damage to restore tree growth and productivity
  • Continued research on improving water and nutrient management programs to maintain productivity of HLB affected citrus trees
  • Progress is also being made on understanding premature fruit drop and what growers can do now to prevent fruit drop prior to harvest

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