How the Asian Citrus Psyllid Brought the Citrus Industry to Its Knees 

Florida is synonymous with oranges. It’s the proud home of Orange County, boasts 569,000 acres of orange groves and offers tourists a special treat with its Florida Citrus Center gas stations filled to the brim with mounds of oranges beckoning you to take a five-pound bag home. 

Floridians have every reason to be proud of their knowledge of every kind of orange and grapefruit on the market, but Florida’s citrus industry isn’t what it used to be. During the 1999 to 2000 season, industry output amounted to a whopping $9.13 billion. In the years since, those earnings have dropped significantly, with the industry output totaling only $6.935 billion in the 2020 to 2021 season. So what’s the cause for such a drastic reduction in earnings? 

Florida’s wonky weather patterns (a.k.a. hurricanes) have played a small part in the disruption of citrus production, but the real culprit is much smaller — and much more lethal. Its name is the Asian citrus psyllid, and it’s caused complete mayhem in the citrus industry. 

Florida Citrus Industry: Then and Now 

Oranges are such a Floridian staple that it’s hard to believe citrus isn’t native to the United States. Oranges, grapefruit, lemons and other citrus fruits originated in Asia. They eventually spread westward, and while the first attempts at cultivation failed in the U.S., Florida became prime real estate for the citrus industry in the 1870s. 

Eventually, scientists created a special blend of orange juice called frozen concentrated orange juice (FCOJ) to ensure that soldiers received adequate amounts of vitamin C while fighting on the frontlines during World War II. Citrus production increased from 43 million boxes in 1945 to 72 million in 1952, largely due to an increase in demand for FCOJ. 

In the 1980s, a series of below-freezing temperatures took a toll on the overall production of citrus. Because of this, many citrus growers began migrating from central and northern regions of Florida to more southern areas that were less likely to freeze. Most growers were able to make a quick comeback and provided large amounts of citrus for processing plants and packing houses. It wasn’t until 2005 that the Asian citrus psyllid invaded thousands of acres of citrus groves, bringing a debilitating, tree-killing disease with it. 

The King of all Citrus Insect Pests: The Asian Citrus Psyllid 

Like citrus, the Asian citrus psyllid originated from Asia. While scientists don’t know exactly how they found their way to the U.S., some believe that someone brought smuggled tree clippings from Asia to Florida in 2005. Asian citrus psyllids are only three to four millimeters in length, but don’t let their scant size fool you. While their appetite for citrus leaves is voracious, that’s not what’s causing the death of so many Florida citrus trees. Rather, it’s the bacteria, Candidatus Liberibacter asciaticus (CLas), that many of these insects carry. The bacteria CLas causes huanglongbing (HLB), a citrus disease that some scientists have compared to HIV in its severity. 

Since Asian citrus psyllids began their reign of terror on citrus trees throughout Florida in 2005, 90% of the state’s orange groves now suffer from HLB, which negatively impacts the citrus industry by: 

  • Reducing fruit quality by preventing fruit from ripening (also known as citrus greening). 
  • Creating dry, lopsided fruit. 
  • Decreasing the overall fruit yield. 
  • Leading to tree decline and eventual death. 

This disruption of citrus production has caused a major decline in the industry, with statistics that include: 

  • Two-thirds of processing fruit factories shut down. 
  • Approximately 5,000 farmers left the industry since 2004 (with about 2,000 remaining) 
  • Citrus packing plants dropped from 80 to 26. 
  • Approximately 34,000 citrus industry jobs were eliminated from 2006 to 2016. 

These invasive pests reproduce so quickly that even insecticides haven’t slowed them down as quickly as farmers had hoped. In addition, Asian citrus psyllids thrive in Florida’s warm weather, so it’s unlikely that they plan on going anywhere anytime soon. And while there’s no cure for trees with HLB, early detection and removal of infected trees is key to preventing its spread. 

The University of Florida is doing its part in the fight against HLB and Asian citrus psyllids. The USDA has recently granted the UF/IFAS faculty from the Citrus Research and Education Center over $16 million to complete a series of research projects that aim to combat the deadly citrus greening disease. 

The University of Florida: Keeping Citrus Around for Years to Come 

With a Graduate Certificate in Landscape Pest Management, you can take your own stand against HLB. Our 15-credit program is entirely online and prepares you for a career in pest control, pest management, entomology and more. 

In addition to required courses like Turf and Ornamental Entomology and Insect Classification, you can choose from exciting electives relevant to your chosen career path, including: 

  • ENY 5212 Insects and Wildlife 
  • IPM 6021 Insect Pest and Vector Management 
  • IPM 5305 Principles of Pesticides 

Take your curiosity and passion for insects and nematodes to the next level by learning more about our program today. 


Learn More About the Program

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