You may have heard about the Asian citrus psyllid (ACP), a tiny insect that spreads a disease called Huanglongbing (HLB) or citrus greening. Infected citrus tree fruits remain green and do not ripen, and the fruit tastes bitter. Diseased trees decline and eventually die. There is no cure.

HLB is fatal to all citrus trees, including lemon, lime, orange, mandarin, grapefruit, pomelo, and relatives like kumquat. Host plants that can harbor the pest include orange jessamine and curry leaf.

The Asian citrus psyllid is small, about the size of a gnat. [Credit: M.E. Rogers, University of Florida]

In Florida, the insect was found in 1998, and the disease was later detected in 2005. Due to HLB and other factors, Florida's citrus industry has been reduced in half over the past decade.

In 2008, the psyllid was found in Los Angeles, and several years later, it made its way to Stanislaus County where it was found on four different residential properties. One finding was in Modesto, another in Oakdale, and two were in Turlock. So far, the disease has only been found in Southern California. To see where ACP and HLB have been found to date, visit this map https://ucanr.edu/sites/ACP/Distribution_of_ACP_in_California/.

So far, trees in Stanislaus County are safe. Unfortunately, the psyllid and disease may advance north. But there are things you can do to help stop this disease.

How You Can Help

Watch this video to learn more about Asian citrus psyllid and Huanglongbing to learn more. You can also visit https://ucanr.edu/sites/ACP/Homeowner_Options/

How UCCE Master Gardeners Will Help

The UCCE Master Gardeners will educate the public about ways to stop the spread of the psyllid through the following messages:

• Purchase citrus from reputable nurseries. Don't accept tree cuttings or budwood from friends or relatives.
• Do not move plants out of quarantined areas.
• If you prune or cut down a citrus tree, dry out the green waste or double bag it to ensure live psyllids can't be moved to another region.
• Control ants in and near citrus trees using bait stations. Ants protect ACP from natural predators.
• Look for ACP on the soft, new succulent leaves of citrus trees and host plants.
• If you believe you have found the psyllid on your plant, call the California Department of Food and Agriculture (CDFA) Hotline immediately at 1-800-491-1899.

For resources in Spanish, visit Noticias en espanol. 

Want to become a UCCE Master Gardener or learn more about the program? Visit our website at https://ucanr.edu/sites/stancountymg/

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