A plant disease that presents a serious threat to the U.S. citrus industry has been detected in Alabama. Federal and state plant health officials have confirmed the identification of citrus canker from foliage and fruit samples collected by the Alabama Department of Agriculture and Industries’ (ADAI) routine citrus survey.
The initial detection was in a residential area of Baldwin County.
Citrus Canker is caused by a bacterial pathogen (Xanthomonas citri subsp. citri Xac) and affects all citrus species. This is the first detection of citrus canker in our state despite biannual surveys conducted by ADAI plant inspection staff.
While not harmful to humans, citrus canker significantly affects the vitality of citrus trees, causing leaves and fruit to drop prematurely. A fruit infected with canker is safe to eat but has reduced marketability as fresh fruit. The bacteria remain viable on plant surfaces for several months. Canker lesions expel bacterial cells, which can be dispersed by wind and rain. Infection may spread further by heavy rain and wind events such as hurricanes.
People can move the disease by moving contaminated equipment and tools, tree clippings, untreated infected fruit, and infected plants. The disease thrives in areas with high rainfall and high temperatures. Citrus species vary in their susceptibility to citrus canker, with grapefruit and limes being the most susceptible.
ADAI and USDA APHIS Plant Protection and Quarantine (PPQ) officials have devised a plan of action. Together they will be conducting a delimiting survey to determine the extent that the pathogen may have spread.
Surveillance teams will survey all citrus within a five-mile radius around each positive site, collect foliage and fruit samples for testing and gather data on the history of symptomatic plants. The delimiting survey will begin in July and will last several weeks. Outreach and education to nurseries, plant dealers, and homeowners will be conducted concerning citrus canker as well.
For more information about citrus canker or questions about the delimiting survey, please contact Christel Stewart by email at Christel.Harden@agi.alabama.gov or by phone at 334-240-7226.