Asian citrus psyllid
By Andrea Peck
My intended focus of discussion this week was the writhing mass of maggots that took up residence in my compost bin for two days, but it turns out a more dire circumstance may be brewing in SLO County.
On March 26, 2014 the notorious Asian citrus psyllid was found in a trap disguised as a floating campsite in Arroyo Grande. The free loader was alone.
The Asian citrus psyllid (ACP), Diaphorina citri, is a small, winged insect, brown in color and approximately the size of an aphid. It typically feeds on citrus trees such as oranges, grapefruit, lemons, and mandarins and a few very closely related ornamental plants in the family Rutaceae (e.g., calamondin, box orange, Indian curry leaf, and orange jessamine or orange jasmine).
The ACP feeds on new leaf growth, leaving the young leaves twisted and curled. New shoots are often lost in the process. But, it is not this feeding habit that is the biggest concern. It is the disease that the ACP transmits. The insect is a vector of the bacterium Candidatus Liberibacter asiaticus, associated with the citrus disease huanglongbing (HLB), also called citrus greening disease. HLB causes leaves to yellow and the fruit to be bitter, hard and misshapen. The inevitable death of the tree occurs in as little as five years. The psyllid can pick up the bacterium when feeding on an infected tree. Once the ACP is infected with the bacterium, it will be a carrier for the remainder of its life and can transfer the disease when feeding on other trees.
In the United States alone, consumption of oranges is higher than that of any other fruit. California is one of the top four citrus producers in the country and the top seller of lemons. The lemon industry in California is valued in the upper $3 million range. With so much at stake it is understandable why concern is at its peak – especially amongst the agricultural community.
Due to the severity of the problem, the USDA has created a new Multi-Agency Coordination (MAC) Group, or emergency response group, to address HLB.
Locally, the Arroyo Grande area is under a mandatory quarantine to within a five mile radius while state and local officials determine the extent of the invasion. This quarantine may be extended in the near future.
Checking your trees at home is not only important for your own garden, but the fate of the commercial industry. Check all citrus trees thoroughly, especially the underside of leaves and areas of new growth. Adult ACPs have a sleek, aerodynamic shape and are known for their distinct feeding habit; the insect appears to be latched on head first into the plant material and its tail end is raised into the air. The nymphs exude a characteristic waxy, white substance that hangs from leaves in a corkscrew-shaped manner. Images abound across the internet – but remember even one insect is cause for alarm and should be reported.
Citrus plants, material or fruit should not be transported outside of quarantined areas. Purchase trees from reputable, licensed California nurseries. When disposing of tree clippings, dry or double bag prior to disposal.
Click here for a map of the quarantine area.
Find more information and photos on the UP IPM and UC Riverside websites - http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn74155.html
Call 1(800) 491-1899 if you suspect your tree has been infested.
Don't forget ! There will be a plant sale of drought tolerant, Mediterranean plants after the June ATGB.
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