June 22, 2017
A healthy crop of satsumas await transportation post-harvest.
A plant disease which presents a serious threat to citrus trees has been detected in Alabama. Plant health officials have confirmed the presence of citrus greening (CG), also known as Huanglongbing, or HLB, which is caused by the bacterial pathogen Candidatus Liberibacter asiaticus.
CG was found in leaf and insect samples from a residential property on Dauphin Island in Mobile County. This is the first confirmation of CG in Alabama despite biannual surveys for the pathogen by the Alabama Department of Agriculture and Industries (ADAI). Surveillance teams will take additional samples for testing, survey the area around the site and gather data on the tree’s history. Outreach and education to nurseries, plant dealers and citrus hobbyists will be conducted concerning CG as well
The ADAI, along with the USDA Animal and Plant Health Inspection Service and the U.S. Department of Homeland Security Customs and Border Protection, will be conducting a delimiting survey to determine the extent the pathogen may have spread. The survey will begin June 26 and should conclude by the end of that week. If the pathogen is limited to only a few trees, steps will be taken to eradicate the disease.
Once a tree is infected there is no known cure or effective control for the disease other than tree removal. Infected trees produce bitter and unusable fruit, spread the disease to surrounding trees and die within three to five years. In areas of the world affected by CG, the average productive lifespan of citrus trees has dropped from 50 or more years to 15 or less.
In Florida, the citrus industry has been significantly affected by the rapid spread of CG. According to a study conducted by University of Florida’s Institute of Food and Agricultural Sciences Extension, orange acreage in the state has been reduced 26 percent and yield decreased 42 percent since the first detection of CG in 2005. Orange production dropped from 242 million boxes to 104.6 million boxes in 2014.
The disease-causing bacteria are spread by the Asian citrus psyllid (ACP). The insect was found in Baldwin County in 2008, but no CG bacteria were detected when molecular analysis of the insects was conducted. The discovery of psyllids in 2008 led to federal and state ACP quarantines of the entire State of Alabama in 2009.
Officials have begun the process to halt movement of citrus plants from the infected area. With confirmation of CG in Dauphin Island, federal plant officials will establish a CG quarantine in Mobile County. Alabama agriculture officials have indicated the state intends to establish a parallel quarantine. The dual action makes it possible for federal regulators to hold the quarantine for CG only in counties in which the disease is present.
For more information about CG or the delimiting survey, please contact Christel Harden at Christel.Harden@agi.alabama.gov or by phone at 334-240-7226.