Citrus greening (also known as yellow dragon disease or huanglongbing) is an incurable disease that affects citrus trees and their relatives. Over time the tree begins to turn yellow, bloom poorly and produce irregularly shaped fruit. The fruit will often have green patches, even when ripe, and be bitter or sour.
This disease is spread by an insect named the Asian citrus psyllid (Diaphorina citri). As the name suggests, this pest originated in Southern Asia, where it has wreaked havoc on their citrus crops. The first Asian citrus psyllids spotted in the United States were found in Florida in 1998. It has since spread to other areas. The following locations are currently under quarantine restrictions:
- Northern Mariana Islands
- Puerto Rico
- South Carolina
- U.S. Virgin Islands
It is important that no citrus trees are moved out of these areas. Doing so can spread the Asian citrus psyllid to new locations.
Host Trees and Shrubs
Signs of Citrus Greening
- The tree will begin to turn yellow in the leaves or become mottled.
- Twig dieback
- The tree has trouble producing flowers and pollination may fail in at least some of the blooms.
- Fruit that is oddly shaped, green in patches when ripe, and bitter or sour fruits.
- Asian citrus psyllids (which are the same approximate size as gnats) are noted on the plant.
There are some predators that will attack the Asian citrus psyllid. They include lacewings, lady beetles (also known as ladybugs), spiders, hover flies and predatory bugs.
Once again, one of the most important factors in limiting citrus greening is to not move plants from quarantine areas. If you are buying a citrus tree online, make sure it is not grown in an affected area. If you own citrus trees, watch for any signs of citrus greening.
If you do find that your tree or shrub has citrus greening, report it to your state agriculture department. They track all cases to monitor the spread of the disease. You can also fill out a report form on SaveOurCitrus.org, a website created by the USDA. They also want reports for citrus canker and citrus black spot.
There are some insecticides approved for control of the Asian citrus psyllid. Check with your extension office for local recommendations.Information compiled from the USDA