Asian Citrus Psyllid

By Leonard Cicerello   UCCE Master Gardener 

How is the fight going against Asian citrus psyllid?  Matt, Cayucos

Asian citrus psyllid (ACP) was first detected in San Diego County in 2008. Since then, county agriculture departments, CDFA, UC Cooperative Extension, and citrus growers have made measurable strides towards limiting the spread of the ACP.  The most visible part of their efforts includes the yellow sticky traps placed in citrus trees by county ag workers in our yards, which are inspected regularly.

ACP is mottled brown and is the size of an aphid.  It damages citrus directly by feeding on new leaves.  This feeding twists and curls young leaves and causes die back of new shoots. Their presence also results in leaves waxy deposits of honeydew which leads to development of sooty mold.

Feeding damage alone will not kill trees; however, ACP is a vector of the deadly disease Huanglongbing (HLB) for which there is no cure.  While the insect has been found in our county, HLB has not. This disease can kill a citrus tree in as little as five years. 

ACP is found in parts of Asia, the Middle East, South and Central America, and the Caribbean. Researchers have found a biological control agent, a parasitic wasp from the Punjab of Pakistan that attacks ACP nymphs. The parasitic wasp is Tamarixia radiata, and after extensive testing and evaluation, the wasp was released in Southern California. It is currently being monitored for their ability to establish its own population and manage ACP populations. 

In certain areas, CDFA is conducting residential insecticide treatments to control the psyllid.  There are also a number of soft foliar insecticides such as oils and soaps (horticultural spray oil, neem oil, insecticidal soap) that can help to reduce psyllids both by killing them and by deterring them from laying eggs.  These insecticides are generally lower risk to beneficial insects (natural enemies and pollinators).

Homeowners can help authorities by inspecting new growth on their trees.  If you suspect you have ACP, please call the CDFA Exotic Pest Hotline at 1-800-491-1899. 

For more information about ACP, HLB and Tamarixia radiata, visit the UC Riverside Center for Invasive Species Research blog - http://cisr.ucr.edu/blog/.