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Citrus Greening

Huanglongbing (HLB), also known as citrus greening, is the most serious disease of citrus. The disease is spread by the Asian citrus psyllid (Diaphorina citri) (ACP), which has been present in Florida since 1998. ACP transmits the bacteria to the tree when feeding on new shoots. There is no cure for this disease and all commercial varieties of citrus are susceptible to HLB.

In citrus-producing areas with little or no HLB incidence, early detection and removal of infected trees are critical to prevent spread of the disease. However, it is difficult to identify HLB-infected trees because they may remain asymptomatic for months to years after infection. Control of the ACP vector and removal of diseased trees are key to maintaining productive citrus. 


Program Information

Huanglongbing (HLB) is thought to have originated in Asia and was first described in the early 1900s. The first detection of HLB in the United States occurred in in Florida in 2005. Since 2005, HLB has spread through the citrus-producing areas in Florida, reducing citrus production by 75%, while more than doubling the cost of production. In 2008, HLB was detected in Louisiana, and in 2009, the disease was detected in Georgia and South Carolina. In 2012, HLB was detected in Texas and residential areas of California.

Symptoms of HLB-infected trees include blotchy mottle leaves, stunted growth, reduced fruit size, premature fruit drop, corky veins, and root decline.  HLB eventually causes tree death.




HLB is currently found throughout Georgia, Florida, Puerto Rico, and the US Virgin Islands and in portions of South Carolina, Louisiana, California, and Texas.

APHIS publishes the legal description of current quarantine areas and these can be accessed in the table below.  Users can search by state and pest to determine the quarantine area(s) by state.

Code of Federal Regulations 301.76

For details on requirements for moving a regulated article, please consult the regulated articles table below. The table is organized by regulated article so users can find the requirements for moving fruit, nursery stock, or other regulated articles.

The citrus nursery stock protocol provides standards and requirements for the interstate movement of citrus nursery stock from areas quarantined for citrus canker, huanglongbing, and/or Asian citrus psyllid. All interstate movement of citrus nursery stock is prohibited unless the conditions in the protocol are met.

The survey protocol for citrus nursery stock describes the rates of inspection, sampling, and testing required by the nursery stock protocol.

Please contact your local Citrus Health Response Program office if you have questions about the protocol.

Citrus Nursery Stock Protocol

Survey Protocol for Citrus Nursery Stock Protocol

How to Help Save Our Citrus

Asian Citrus Psyllid

Huanglongbing (HLB) is spread by a tiny insect, the Asian citrus psyllid (ACP, Diaphorina citri). First detected in Florida in 1998, ACP spread to Texas in 2001, California in 2008, and Arizona in 2009. ACP is now present in all citrus growing regions of the United States.

ACP reproduce on newly developing leaves, and while the insect itself causes little direct feeding damage, the insect can carry the bacteria that causes huanglongbing (Candidatus Liberibacter asiaticus, CLas). ACP can transmit HLB to uninfected citrus trees as it feeds.


Citrus Black Spot

Citrus black spot (CBS), which is caused by the fungal pathogen Phyllostricta citricarpa (previously known as Guignardia citricarpa) was first found in south Florida, near Immokalee, in March 2010. CBS symptoms on fruit include hard spot, cracked spot, false melanose, freckle spot or early virulent spot, and virulent spot. Symptoms of CBS are easiest to observe during color break, when fruit turns from green to ripe coloration. When trees are severely infected, CBS can cause premature fruit drop before harvest, resulting in significant yield loss.

CBS is spread when wind-borne spores embed in the leaf litter under trees and are carried long distances by air currents. Rain splash may move spores short distances from infected fruit and/or leaf litter. Human-assisted movement of fruit and infected nursery stock is the main form of long distance movement.


Citrus Canker

Citrus canker is a disease caused by the bacterium, Xanthomonas citri subspecies citri. Infection causes lesions on the leaves, stems, and fruit of citrus trees. Typical lesions of the disease are raised, tan to brown in color, and have a water-soaked margin and yellow halos. The bacteria propagate in the lesions, which ooze bacterial cells that are dispersed by windblown rain, contaminated equipment, and movement of infected plants.

While not harmful to humans, uncontrolled canker infection can significantly affect tree health, causing leaves and fruit to drop prematurely. A fruit infected with canker is safe to eat, but its appearance can decrease its marketability.

Canker originated in southeast Asia. Citrus canker was first detected in the United States in 1910 and was eradicated in 1933. It was discovered again in 1995 in Miami-Dade County, Florida. Despite an aggressive tree removal program, USDA was not able to eliminate canker in Florida a second time and ended eradication efforts in 2006.  Canker is present in Florida, Louisiana, and parts of Texas.


Citrus Greening

Huanglongbing (HLB, also known as citrus greening) is the most serious citrus disease in the world and is caused by the bacterium Candidatus Liberibacter asiaticus. There is no cure for this disease once a tree is infected. While the disease poses no threat to humans or animals, it has devastated millions of acres of citrus production around the world, including in the United States.

HLB has been known in Asia since 1900, and Africa since 1920. The first detection of HLB in the Americans was in Brazil in 2004. The first detection of HLB in the United States was in Florida in 2005. HLB has been detected in all the major citrus growing states in the United States, except Arizona.

Once a tree is infected with the bacteria, the tree can remain without detectable symptoms for months or years. During this symptomless phase, the tree can serve as a source of bacteria to infect other trees. Over time, an infected tree will start producing fewer fruit that are smaller, shaped irregulary, and taste bitter. Affected trees have leaves with blotchy mottling, stunted growth, root die-back, and are prone to dropping fruit before it is ripe. Trees infected with HLB will eventually succumb to the disease.


Sweet Orange Scab

Sweet orange scab (SOS) is a disease caused by the fungus Elsinöe australis, which results in scab-like lesions primarily on fruit. The fruit are safe to eat, but the blemishes result in reduced marketability in the fresh fruit market. SOS can cause premature fruit drop and stunt young nursery trees and new field plantings.

SOS was first detected in the United States in 2010 in Texas. SOS is now confirmed in Louisiana, Florida, Mississippi, Texas, Arizona, and parts of California.

Moving citrus trees is the fastest way that citrus diseases are spread. When you move citrus trees, you risk losing America’s citrus.

You Can Help Prevent Citrus Disease

Citrus Story Map

If you think you have identified an infected plant, report it immediately. To avoid spreading the disease, do not move your plant. Complete the "Report It" form below or call your local  USDA State Plant Health Director’s office.

Report It Form (English) 
 Report It Form (Espanol) 


If you are younger than 18 years of age, please ask a parent, guardian or trusted adult to help you complete the form. 

Thank you for helping stop the spread of citrus disease!

Salve los Cítricos: Ayude a eliminar las enfermedades de los cítricos


Save Our Citrus: Put the Squeeze on Citrus Disease

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