A residential grapefruit tree in the city of Riverside has tested positive for the incurable citrus disease Huanglongbing, or HLB, which causes the citrus greening disease. This is the first case of the disease in Riverside. It has already been detected in LA and Orange Counties. It was found after several Asian citrus psyllids (or the insect that moves the bacteria from tree to tree) trapped in the area tested positive.
After the results came back July 25, the tree was removed the following morning. A nearby tree is also being tested and all trees within an 800-meter radius from the infected tree that are susceptible to the disease will be treated to reduce the numbers of Asian citrus psyllids.
Infected trees have mottled leaves and fruit that is misshapen the fruit stays green and has a bitter taste. There is no known treatment for the disease and trees usually die within three to five years.
Researchers at UC Riverside and in UC ANR are working on biological controls, testing for effective insecticides, developing resistant citrus trees, and finding ways to detect infected trees earlier.
Information sheets, videos in English and Spanish, and other resources can be viewed and downloaded here. They can help in identifying the Asian citrus psyllid and the disease symptoms and how you can help in the fight against this devastating disease.
If you see any trees that have any symptoms, contact your agriculture commissioner.
Information is also available on the state's Dept. of food and agriculture website. If you believe you may have an infected tree, call the California Department of Food and Agriculture at 800-491-1899.
Author - Area Integrated Pest Management Advisor - Emeritus