Citrus Greening Disease Threatens Florida's Orchards

The Citrus Greening Crisis

Citrus greening disease, scientifically known as Huanglongbing (HLB), is considered the most serious citrus disease worldwide. Caused by the bacterium Candidatus Liberibacter asiaticus and spread by the Asian citrus psyllid (Diaphorina citri), the disease has been present in Florida since 2005 and has reduced the state's citrus production by more than 70%.

How Citrus Greening Spreads

The disease cycle involves two key players:

• Asian citrus psyllid - This tiny insect feeds on new citrus growth and transmits the bacterium from tree to tree. A single psyllid can infect multiple trees.
• Candidatus Liberibacter asiaticus - The bacterium colonizes the phloem (food-conducting tissue) of citrus trees, blocking nutrient transport and slowly killing the tree.

Infected trees may not show symptoms for months or even years, allowing the disease to spread undetected through groves and residential landscapes.

Identifying Citrus Greening

Watch for these symptoms on citrus trees:

• Asymmetric leaf yellowing (blotchy mottling) that does not follow leaf veins
• Lopsided, misshapen fruit that remains partially green even when ripe
• Fruit with bitter, off-flavor juice and aborted seeds
• Twig dieback and general decline in canopy density
• Small, upright leaves on affected branches
• Overall tree decline with reduced fruit production year over year

It is important to note that nutrient deficiencies can mimic some symptoms. Try our diagnose tool for initial assessment, though laboratory testing is required for definitive diagnosis.

Current State of the Outbreak

The impact on Florida's citrus industry has been staggering:

• Florida produced 240 million boxes of oranges annually before HLB; recent seasons have produced fewer than 20 million
• Thousands of acres of groves have been abandoned
• The disease has now been detected in Texas, Louisiana, Georgia, South Carolina, and California
• Residential citrus trees across the southern United States are increasingly affected

Research and Management Efforts

Scientists and growers are pursuing multiple strategies:

• Psyllid control programs using systemic insecticides and area-wide coordinated spray programs
• Nutritional therapies that supplement trees with micronutrients to maintain production despite infection
• Thermotherapy using portable steam equipment to heat trees and suppress bacterial loads
• Resistant rootstock development through conventional breeding and genetic research
• CRISPR gene editing to develop citrus varieties with natural resistance
• Biological control using Tamarixia radiata, a parasitoid wasp that attacks psyllids

What Homeowners Can Do

If you have citrus trees in an affected area:

• Control Asian citrus psyllids with appropriate insecticide applications
• Remove and destroy trees that are confirmed positive for HLB
• Do not move citrus plant material from quarantine areas
• Report suspected infections to your county extension office or find a certified arborist for assessment
• Consider planting disease-tolerant varieties being developed by university breeding programs — use our tree identification tool to learn about alternatives