Worldwide, a disease threatens to wipe out citrus trees: orange, grapefruit, tangerine, kumquat, lime, lemon and others. The gigantic threat stems from a tiny pest, the Asian citrus psyllid (ACP).
ACP is a small insect with needle-like mouthparts it uses to pierce plants and suck out the juices. It prefers to feed and reproduce on the new leaf growth of citrus and closely related plant species, such as orange jasmine.
The immature stages (or nymphs) of ACP must feed on the new leaf growth to survive. In addition to the feeding damage it causes to the leaves, ACP often carries a disease called huanglongbing (HLB). Some people also refer to it as citrus greening disease.
HLB is considered one of the most devastating citrus diseases, and there is no known cure for it. ACP doesn’t always carry the disease, but the disease can’t spread without the insect. Symptoms of the disease include yellow shoots and lopsided fruit with a bitter taste. It can take up to three years for HLB symptoms to be visible in a citrus tree. Infected trees produce inedible fruits and eventually die. Citrus trees infected with the disease must be destroyed.
Types of Citrus Trees That ACP Infests
According to the U.S. Department of Agriculture, ACP favors citrus plants and citrus relatives, including the highly susceptible sweet orange and mandarin orange, as well as lemon, lime, tangerine, grapefruit and kumquat. To learn what plants host ACP, download this pdf from the Florida Department of Agriculture.
The following states and territories are under quarantine for ACP: Alabama, Mississippi, Louisiana, Texas, Hawaii, Guam, and parts of Arizona and Southern California. Florida, Georgia, Puerto Rico, U.S. Virgin Islands, and parts of South Carolina and Louisiana are under quarantine for both ACP and HLB disease. For a map, visit saveourcitrus.org.
How To Tell If Your Tree Has ACP
The ACP damages new growth because it injects toxins into the citrus plant or tree while it feeds. This causes curling and distortion of young leaves.
ACP is most likely to be found on new shoots, and the insect population increases during periods of active plant growth. The tiny adults look like aphids, measuring about 1/8 inch. Their bodies are grayish tan with brown markings and mottled brown wings. The last two segments of antennae are black.
Battling ACP and HLB
Protect your trees against citrus psyllid with foliar sprays or a systemic insecticide soil drench applied prior to the flush of new growth, which adult psyllids favor for laying eggs.
It’s very important to collect samples of any insect or insect damage on citrus trees. Put the sample in a plastic storage bag and call county officials.
If you live in California and see signs of ACP, call the California Department of Food and Agriculture or county ag commissioner in your area. CDFA Pest Hotline: (800) 491-1899.
If you live in Florida and see signs of ACP or HLB disease, call the Division of Plant Industry at (800) 282-5153.