UC Master Gardeners

Asian citrus psyllid can be fatal to backyard trees

UC Master GardenerNovember 6, 2013 

Q: I heard the bug that is killing citrus trees was found in Tulare County. Is that true? — Sarah B., Arroyo Grande

A: As of Oct.1, the Tulare County Agricultural Commissioner reported that two Asian citrus psyllids were found in traps in Tulare County. San Luis Obispo County is surrounded by quarantined areas — Santa Barbara County to the south and portions of Kern and Tulare County to the east.

San Luis Obispo County trappers are diligently checking citrus plants for the adults and nymphs of the ACP, but they can also use your help.

This not only threatens California’s citrus industry, but also those residents who cherish their backyard citrus trees. The Asian citrus psyllid feeds on the leaves and stems of citrus and also carries the Huanglongbing (HLB), or citrus greening disease, a fatal disease for which there is no cure. Huanglongbing will kill a tree in as little as five years.

In addition to citrus, ACP has a long list of host plants, including ornamental plants in the Rutaceae family. One of the most common is the orange jasmine. There are insecticides formulated to treat ACP infestation, but not the disease. The insecticide must be used judiciously, as it can also harm bees and natural enemies of the pest.

With thousands of backyard citrus trees in the county, home gardeners are a very important asset in helping to exclude this pest from our county. Home gardeners’ most important task is to inspect their citrus trees and other related plants regularly from spring through fall. Nymphs and adults feed on young flush growth.

Adults are 1/8-inch in size, about the size of an aphid, with brownish mottled wings. They feed with their heads down and “tails” in the air. Nymphs are tiny and yellowish and excrete white waxy tubules.

Residents can also help by not moving citrus plants or plant material out of quarantined areas. Doing so only jeopardizes quarantine efforts. Even if you do not see any evidence of infestation or HLB, please do not move material out of aquarantined area.

If you suspect you may have ACP, contact the San Luis Obispo Agriculture Dept. immediately at 781-5910, or the CDFA hotline at 800-491-1899. For more information on ACP, visit the UC Davis Pest Notes at http://www.ipm.ucdavis.edu.

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